transforming-growth-factor-beta and Renal-Insufficiency--Chronic

Renal fibrosis is the inevitable common end-point of all progressive chronic kidney diseases. The underlying mechanisms of renal fibrosis are complex, and currently there is no effective therapy against renal fibrosis. Renal microvascular rarefaction contributes to the progression of renal fibrosis; however, an imbalance between proangiogenic and antiangiogenic factors leads to the loss of renal microvasculature. Vascular endothelial growth factor (VEGF) is the most important pro-angiogenic factor. Recent studies have unraveled the involvement of VEGF in the regulation of renal microvascular rarefaction and fibrosis

Topics: Animals; Fibrosis; Mice; Mice, Inbred C57BL; Microvascular Rarefaction; Nitric Oxide; Renal Insufficiency, Chronic; Soluble Guanylyl Cyclase; Transforming Growth Factor beta; Vascular Endothelial Growth Factor A

Kidney fibrosis, characterized by excessive deposition of extracellular matrix (ECM) that leads to tissue scarring, is the final common outcome of a wide variety of chronic kidney diseases. Rather than being distributed uniformly across the kidney parenchyma, renal fibrotic lesions initiate at certain focal sites in which the fibrogenic niche is formed in a spatially confined fashion. This niche provides a unique tissue microenvironment that is orchestrated by a specialized ECM network consisting of de novo-induced matricellular proteins. Other structural elements of the fibrogenic niche include kidney resident and infiltrated inflammatory cells, extracellular vesicles, soluble factors and metabolites. ECM proteins in the fibrogenic niche recruit soluble factors including WNTs and transforming growth factor-β from the extracellular milieu, creating a distinctive profibrotic microenvironment. Studies using decellularized ECM scaffolds from fibrotic kidneys show that the fibrogenic niche autonomously promotes fibroblast proliferation, tubular injury, macrophage activation and endothelial cell depletion, pathological features that recapitulate key events in the pathogenesis of chronic kidney disease. The concept of the fibrogenic niche represents a paradigm shift in understanding of the mechanism of kidney fibrosis that could lead to the development of non-invasive biomarkers and novel therapies not only for chronic kidney disease, but also for fibrotic diseases of other organs.

Topics: Extracellular Matrix; Fibrosis; Humans; Kidney; Renal Insufficiency, Chronic; Transforming Growth Factor beta

Renal fibrosis contributes to progressive damage to renal structure and function. It is a common pathological process as chronic kidney disease develops into kidney failure, irrespective of diverse etiologies, and eventually leads to death. However, there are no effective drugs for renal fibrosis treatment at present. Lipid aggregation in the kidney and consequent lipotoxicity always accompany chronic kidney disease and fibrosis. Numerous studies have revealed that restoring the defective fatty acid oxidation in the kidney cells can mitigate renal fibrosis. Thus, it is an important strategy to reverse the dysfunctional lipid metabolism in the kidney, by targeting critical regulators of lipid metabolism. In this review, we highlight the potential "druggability" of lipid metabolism to ameliorate renal fibrosis and provide current pre-clinical evidence, exemplified by some representative druggable targets and several other metabolic regulators with anti-renal fibrosis roles. Then, we introduce the preliminary progress of noncoding RNAs as promising anti-renal fibrosis drug targets from the perspective of lipid metabolism. Finally, we discuss the prospects and deficiencies of drug targeting lipid reprogramming in the kidney.

Topics: Animals; Carnitine O-Palmitoyltransferase; CD36 Antigens; Epithelial Cells; Fatty Acids; Fibrosis; Inflammation; Kidney; Lipid Metabolism; MicroRNAs; Peroxisome Proliferator-Activated Receptors; Renal Insufficiency, Chronic; RNA, Untranslated; Sterol Regulatory Element Binding Proteins; Transforming Growth Factor beta

Acute kidney injury (AKI) is defined as a rapid decline in renal function and is characterized by excessive renal inflammation and programmed death of resident cells. AKI shows high morbidity and mortality, and severe or repeated AKI can transition to chronic kidney disease (CKD) or even end-stage renal disease (ESRD); however, very few effective and specific therapies are available, except for supportive treatment. Growth factors, such as epidermal growth factor (EGF), insulin-like growth factor (IGF), and transforming growth factor-β (TGF-β), are significantly altered in AKI models and have been suggested to play critical roles in the repair process of AKI because of their roles in cell regeneration and renal repair. In recent years, a series of studies have shown evidence that growth factors, receptors, and downstream effectors may be highly involved in the mechanism of AKI and may function in the early stage of AKI in response to stimuli by regulating inflammation and programmed cell death. Moreover, certain growth factors or correlated proteins act as biomarkers for AKI due to their sensitivity and specificity. Furthermore, growth factors originating from mesenchymal stem cells (MSCs) via paracrine signaling or extracellular vesicles recruit leukocytes or repair intrinsic cells and may participate in AKI repair or the AKI-CKD transition. In addition, growth factor-modified MSCs show superior therapeutic potential compared to that of unmodified controls. In this review, we summarized the current therapeutic and diagnostic strategies targeting growth factors to treat AKI in clinical trials. We also evaluated the possibilities of other growth factor-correlated molecules as therapeutic targets in the treatment of AKI and the AKI-CKD transition.

Topics: Acute Kidney Injury; Disease Progression; Epidermal Growth Factor; Humans; Intercellular Signaling Peptides and Proteins; Molecular Targeted Therapy; Renal Insufficiency, Chronic; Signal Transduction; Somatomedins; Transforming Growth Factor beta

Renal fibrosis is characterized by excessive deposition of extracellular matrix (ECM) that disrupts and replaces functional parenchyma, which leads to organ failure. It is known as the major pathological mechanism of chronic kidney disease (CKD). Although CKD has an impact on no less than 10% of the world population, therapeutic options are still limited. Regardless of etiology, elevated TGF-β levels are highly correlated with the activated pro-fibrotic pathways and disease progression. TGF-β, the key driver of renal fibrosis, is involved in a dynamic pathophysiological process that leads to CKD and end-stage renal disease (ESRD). It is becoming clear that epigenetics regulates renal programming, and therefore, the development and progression of renal disease. Indeed, recent evidence shows TGF-β1/Smad signaling regulates renal fibrosis via epigenetic-correlated mechanisms. This review focuses on the function of TGF-β/Smads in renal fibrogenesis, and the role of epigenetics as a regulator of pro-fibrotic gene expression.

Topics: Fibrosis; Humans; Kidney; Renal Insufficiency, Chronic; Signal Transduction; Smad Proteins; Transforming Growth Factor beta

Elevated circulating levels of growth hormone (GH) and/or increased expression of the GH receptor in the kidney are associated with the development of nephropathy in type1 diabetes and acromegaly. Conditions of GH excess are characterized by hyperfiltration, glomerular hypertrophy, glomerulosclerosis and albuminuria, whereas states of decreased GH secretion or action are protected against glomerulopathy. The direct role of GH's action on glomerular cells, particularly podocytes, has been the focus of recent studies. In this review, the emerging role of GH on the biological function of podocytes and its implications in the pathogenesis of diabetic and chronic kidney disease will be discussed.. Elevated GH levels impair glomerular permselectivity by altering the expression of podocyte slit-diaphragm proteins. GH stimulates the epithelial-mesenchymal transition of podocytes and decreases podocyte count. GH also induces the expression of prosclerotic molecules transforming growth factor beta, and TGFBIp.. Our understanding of the cellular and molecular effects of GH in the pathogenesis of renal complications of diabetes and acromegaly has significantly progressed in recent years. These observations open up new possibilities in the prevention and treatment of diabetic nephropathy.

Topics: Animals; Diabetic Nephropathies; Epithelial-Mesenchymal Transition; Growth Hormone; Humans; Kidney; Podocytes; Renal Insufficiency, Chronic; Transforming Growth Factor beta

The incidence of chronic kidney diseases (CKDs) is expected to rise, fuelled by the ever increasing epidemic of Type 2 diabetes. Despite extensive research in this area, there are currently no effective treatments available to sufficiently halt the progression of CKD towards renal failure. This is largely due to ongoing secondary pathological processes generally elicited by the onset of disease. Fibrosis, in particular, is a prominent pathological hallmark of many forms of CKD and considered to be a central contributing factor for the progression of CKD towards end-stage renal disease. Transforming growth factor β (TGFβ) has been implicated to be a major regulatory cytokine in CKD, especially in fibrosis development, and reduced TGFβ signalling activity has been previously shown to be associated with improved renal outcomes in experimental animal studies. A number of molecules related to and/or interacting with the TGFβ signalling pathway have been identified as potential therapeutic targets. However, due to its pleiotropic nature, complete inhibition of the TGFβ signalling pathway is likely to lead to deleterious side effects. Therefore, a better understanding of this pathway and the molecules modulating this pathway is necessary to develop more efficacious and therapeutic strategies to combat progression of CKD.

Topics: Animals; Disease Progression; Fibrosis; Humans; Kidney; Renal Insufficiency, Chronic; Signal Transduction; Transforming Growth Factor beta

Transforming growth factor-β (TGF-β) is a key profibrotic growth factor that is activated in acute kidney injury (AKI) and associated with cellular responses that lead to the development of chronic kidney disease (CKD). The persistently injured, de-differentiated tubular epithelial cell is an important mediator of the transition from AKI to CKD. TGF-β signaling may perpetuate proximal tubule injury through de-differentiation, cell cycle arrest, and increased susceptibility to apoptosis. In addition, TGF-β signaling promotes macrophage chemotaxis, endothelial injury, and myofibroblast differentiation after AKI. Future studies that block TGF-β signaling after cessation of AKI are needed to better define its role in the progression of acute to chronic renal injury.

Topics: Acute Kidney Injury; Animals; Disease Progression; Humans; Renal Insufficiency, Chronic; Signal Transduction; Transforming Growth Factor beta

Renal fibrosis is an important component of chronic kidney disease, an incurable pathology with increasing prevalence worldwide. With a lack of available therapeutic options, end-stage renal disease is currently treated with renal replacement therapy through dialysis or transplantation. In recent years, many efforts have been made to identify novel targets for therapy of renal diseases, with special focus on the characterization of unknown mediators and pathways participating in renal fibrosis development. Using experimental models of renal disease and patient biopsies, we identified four novel mediators of renal fibrosis with potential to constitute future therapeutic targets against kidney disease: discoidin domain receptor 1, periostin, connexin 43, and cannabinoid receptor 1. The four candidates were highly upregulated in different models of renal disease and were localized at the sites of injury. Subsequent studies showed that they are centrally involved in the underlying mechanisms of renal fibrosis progression. Interestingly, inhibition of either of these proteins by different strategies, including gene deletion, antisense administration, or specific blockers, delayed the progression of renal disease and preserved renal structure and function, even when the inhibition started after initiation of the disease. This review will summarize the current findings on these candidates emphasizing on their potential to constitute future targets of therapy.

Topics: Animals; Cell Adhesion Molecules; Connexin 43; Discoidin Domain Receptor 1; Drug Discovery; Extracellular Matrix; Fibrosis; Humans; Kidney; Molecular Targeted Therapy; Receptor, Cannabinoid, CB1; Renal Insufficiency, Chronic; Transforming Growth Factor beta

Thrombospondin 1 (TSP1) is a matricellular extracellular matrix protein that has diverse roles in regulating cellular processes important for the pathogenesis of fibrotic diseases. We will present evidence for the importance of TSP1 control of latent transforming growth factor beta activation in renal fibrosis with an emphasis on diabetic nephropathy. Other functions of TSP1 that affect renal fibrosis, including regulation of inflammation and capillary density, will be addressed. Emerging roles for TSP1 N-terminal domain regulation of collagen matrix assembly, direct effects of TSP1-collagen binding, and intracellular functions of TSP1 in mediating endoplasmic reticulum stress responses in extracellular matrix remodeling and fibrosis, which could potentially affect renal fibrogenesis, will also be discussed. Finally, we will address possible strategies for targeting TSP1 functions to treat fibrotic renal disease.

Topics: Animals; Collagen; Diabetic Nephropathies; Extracellular Matrix; Fibrosis; Humans; Kidney; Renal Insufficiency, Chronic; Thrombospondin 1; Transforming Growth Factor beta

Chronic kidney disease (CKD) has emerged as a major cause of morbidity and mortality worldwide. Interstitial fibrosis, glomerulosclerosis and inflammation play the central role in the pathogenesis and progression of CKD to end stage renal disease (ESRD). Transforming growth factor-β1 (TGF-β1) is the central mediator of renal fibrosis and numerous studies have focused on inhibition of TGF-β1 and its downstream targets for treatment of kidney disease. However, blockade of TGF-β1 has not been effective in the treatment of CKD patients. This may be, in part due to anti-inflammatory effect of TGF-β1. The Smad signaling system plays a central role in regulation of TGF-β1 and TGF-β/Smad pathway plays a key role in progressive renal injury and inflammation. This review provides an overview of the role of TGF-β/Smad signaling pathway in the pathogenesis of renal fibrosis and inflammation and an effective target of anti-fibrotic therapies. Under pathological conditions, Smad2 and Smad3 expression are upregulated, while Smad7 is downregulated. In addition to TGF-β1, other pathogenic mediators such as angiotensin II and lipopolysaccharide activate Smad signaling through both TGF-β-dependent and independent pathways. Smads also interact with other pathways including nuclear factor kappa B (NF-κB) to regulate renal inflammation and fibrosis. In the context of renal fibrosis and inflammation, Smad3 exerts profibrotic effect, whereas Smad2 and Smad7 play renal protective roles. Smad4 performs its dual functions by transcriptionally promoting Smad3-dependent renal fibrosis but simultaneously suppressing NF-κB-mediated renal inflammation via Smad7-dependent mechanism. Furthermore, TGF-β1 induces Smad3 expression to regulate microRNAs and Smad ubiquitination regulatory factor (Smurf) to exert its pro-fibrotic effect. In conclusion, TGF-β/Smad signaling is an important pathway that mediates renal fibrosis and inflammation. Thus, an effective anti-fibrotic therapy via inhibition of Smad3 and upregulation of Smad7 signaling constitutes an attractive approach for treatment of CKD.

Topics: Animals; Disease Progression; Drug Delivery Systems; Humans; Renal Agents; Renal Insufficiency, Chronic; Signal Transduction; Smad Proteins; Transforming Growth Factor beta; Treatment Outcome

Y-box-binding protein 1 (YB-1) is a multifunctional protein involved in various cellular processes via the transcriptional and translational regulation of target gene expression. YB-1 promotes acute or chronic kidney injury through multiple molecular pathways; however, accumulating evidence suggests that significantly increased YB-1 levels are of great importance in renoprotection. In addition, YB-1 may contribute to obesity-related kidney disease by promoting adipogenesis. Thus, the role of YB-1 in kidney injury is complicated, and no comprehensive review is currently available. In this review, we summarise recent progress in our understanding of the function of YB-1 in kidney injury and provide an overview of the dual role of YB-1 in kidney disease. Moreover, we propose that YB-1 is a potential therapeutic target to restrict kidney disease.

Topics: Acute Kidney Injury; Epithelial-Mesenchymal Transition; Humans; Renal Insufficiency, Chronic; Signal Transduction; Transforming Growth Factor beta; Y-Box-Binding Protein 1

Sotatercept and luspatercept are recombinant soluble activin type-II receptor-IgG-Fc fusion proteins that are tested in clinical trials for the treatment of various types of anemias, including renal anemia. The mechanism of the action of the novel drugs is incompletely understood, but it seems to be based on the inactivation of soluble proteins of the transforming growth factor-ß (TGFß) family. This review considers pros and cons of the clinical use of the drugs in reference to the current therapy with recombinant erythropoiesis-stimulating agents (ESAs).. One or more activin type-II receptor (ActRII) ligands appear to inhibit erythroid precursors, for example growth and differentiation factor 11. Trapping of these ligands by the recombinant ActRII fusion proteins, sotatercept and luspatercept increases red blood cell numbers and hemoglobin levels in humans. Reportedly, the novel compounds were well tolerated in trials on healthy volunteers and patients suffering from anemia due to chronic kidney disease or malignancies. On approval, the drugs may prove particularly useful in patients suffering from ineffective erythropoiesis, such as in myelodysplastic syndrome, multiple myeloma or ß-thalassemia, where ESAs are of little use. Independent of their effect on erythropoiesis, ActRII ligand traps were found to exert beneficial effects on renal tissue in experimental animals.. ESAs are likely to remain standard of care in renal anemia. There is a need for a better understanding of the effects of ActRII ligand traps on TGFß-like proteins. The novel drugs have not been approved for sale as therapeutics so far. Their long-term efficacy and safety still needs to be proven, particularly with respect to immunogenicity. Antifibrotic effects may be worthy to be investigated in humans.

Topics: Activin Receptors; Activin Receptors, Type II; Activins; Anemia; Animals; Erythropoiesis; Hematinics; Humans; Immunoglobulin Fc Fragments; Ligands; Recombinant Fusion Proteins; Renal Insufficiency, Chronic; Transforming Growth Factor beta

Transforming growth factor (TGF)-β signaling is not only important in skeletal development, but also essential in bone remodeling in adult bone. The bone remodeling process involves integrated cell activities induced by multiple stimuli to balance bone resorption and bone formation. TGF-β plays a role in bone remodeling by coordinating cell activities to maintain bone homeostasis. However, mineral metabolism disturbance in chronic kidney disease (CKD) results in abnormal bone remodeling, which leads to ectopic calcification in CKD. High circulating levels of humoral factors such as parathyroid hormone, fibroblast growth factor 23, and Wnt inhibitors modulate bone remodeling in CKD. Several reports have revealed that TGF-β is involved in the production and functions of these factors in bone. TGF-β may act as a factor that mediates abnormal bone remodeling in CKD.

Topics: Animals; Bone and Bones; Bone Remodeling; Fibroblast Growth Factor-23; Fibroblast Growth Factors; Humans; Renal Insufficiency, Chronic; Transforming Growth Factor beta; Wnt Signaling Pathway

Lymphatic vessels drain excess tissue fluids to maintain the interstitial environment. Lymphatic capillaries develop during the progression of tissue fibrosis in various clinical and pathological situations, such as chronic kidney disease, peritoneal injury during peritoneal dialysis, tissue inflammation, and tumor progression. The role of fibrosis-related lymphangiogenesis appears to vary based on organ specificity and etiology. Signaling via vascular endothelial growth factor (VEGF)-C, VEGF-D, and VEGF receptor (VEGFR)-3 is a central molecular mechanism for lymphangiogenesis. Transforming growth factor-β (TGF-β) is a key player in tissue fibrosis. TGF-β induces peritoneal fibrosis in association with peritoneal dialysis, and also induces peritoneal neoangiogenesis through interaction with VEGF-A. On the other hand, TGF-β has a direct inhibitory effect on lymphatic endothelial cell growth. We proposed a possible mechanism of the TGF-β⁻VEGF-C pathway in which TGF-β promotes VEGF-C production in tubular epithelial cells, macrophages, and mesothelial cells, leading to lymphangiogenesis in renal and peritoneal fibrosis. Connective tissue growth factor (CTGF) is also involved in fibrosis-associated renal lymphangiogenesis through interaction with VEGF-C, in part by mediating TGF-β signaling. Further clarification of the mechanism might lead to the development of new therapeutic strategies to treat fibrotic diseases.

Topics: Animals; Connective Tissue Growth Factor; Epithelial Cells; Gene Expression Regulation; Humans; Lymphangiogenesis; Lymphatic Vessels; Macrophages; Nephrogenic Fibrosing Dermopathy; Peritoneal Fibrosis; Renal Insufficiency, Chronic; Signal Transduction; Transforming Growth Factor beta; Vascular Endothelial Growth Factor C; Vascular Endothelial Growth Factor D; Vascular Endothelial Growth Factor Receptor-3

Acute kidney injury (AKI) and chronic kidney disease (CKD) are interconnected. Although AKI-to-CKD transition has been intensively studied, the information of AKI on CKD is very limited. Nonetheless, AKI, when occurring in patients with CKD, is known to be more severe and difficult to recover. CKD is associated with significant changes in cell signaling in kidney tissues, including the activation of transforming growth factor-β, p53, hypoxia-inducible factor, and major developmental pathways. At the cellular level, CKD is characterized by mitochondrial dysfunction, oxidative stress, and aberrant autophagy. At the tissue level, CKD is characterized by chronic inflammation and vascular dysfunction. These pathologic changes may contribute to the heightened sensitivity of, and nonrecovery from, AKI in patients with CKD.

Topics: Acute Kidney Injury; Autophagy; Basic Helix-Loop-Helix Transcription Factors; DNA Methylation; Epigenesis, Genetic; Humans; Inflammation; Kidney; Mitochondria; Oxidative Stress; Renal Insufficiency, Chronic; Risk Factors; Signal Transduction; Transforming Growth Factor beta; Tumor Suppressor Protein p53

Current treatment modalities are not effective in halting the progression of most CKD. Renal fibrosis is a pathological process common to all CKD and thereby represents an excellent treatment target. A large number of molecular pathways involved in renal fibrosis were identified in preclinical studies, some of them being similar among different organs and some with available drugs in various phases of clinical testing. Yet only few clinical trials with antifibrotic drugs are being conducted in CKD patients. Here we review those clinical trials, focusing on agents with direct antifibrotic effects, with particular focus on pirfenidone and neutralizing antibodies directed against profibrotic growth factors and cell connection proteins. We discuss the potential reasons for the poor translation in treatment of renal fibrosis and propose possible approaches and future developments to improve it, eg, patient selection and companion diagnostics, specific and sensitive biomarkers as novel end points for clinical trials, and drug-targeting and theranostics.

Topics: Anti-Inflammatory Agents, Non-Steroidal; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antibodies, Neutralizing; Biomarkers; Connective Tissue Growth Factor; Elasticity Imaging Techniques; Endpoint Determination; Extracellular Matrix; Fibrosis; Galectin 3; Humans; Kidney; Magnetic Resonance Imaging; Polysaccharides; Pyridones; Renal Insufficiency, Chronic; Transforming Growth Factor beta

Transforming growth factor-β (TGF-β) is the primary factor that drives fibrosis in most, if not all, forms of chronic kidney disease (CKD). Inhibition of the TGF-β isoform, TGF-β1, or its downstream signalling pathways substantially limits renal fibrosis in a wide range of disease models whereas overexpression of TGF-β1 induces renal fibrosis. TGF-β1 can induce renal fibrosis via activation of both canonical (Smad-based) and non-canonical (non-Smad-based) signalling pathways, which result in activation of myofibroblasts, excessive production of extracellular matrix (ECM) and inhibition of ECM degradation. The role of Smad proteins in the regulation of fibrosis is complex, with competing profibrotic and antifibrotic actions (including in the regulation of mesenchymal transitioning), and with complex interplay between TGF-β/Smads and other signalling pathways. Studies over the past 5 years have identified additional mechanisms that regulate the action of TGF-β1/Smad signalling in fibrosis, including short and long noncoding RNA molecules and epigenetic modifications of DNA and histone proteins. Although direct targeting of TGF-β1 is unlikely to yield a viable antifibrotic therapy due to the involvement of TGF-β1 in other processes, greater understanding of the various pathways by which TGF-β1 controls fibrosis has identified alternative targets for the development of novel therapeutics to halt this most damaging process in CKD.

Topics: Animals; Fibrosis; Histones; Humans; Kidney; MicroRNAs; Renal Insufficiency, Chronic; Signal Transduction; Smad Proteins; Transforming Growth Factor beta

The increase in the prevalence of diabetes mellitus (DM) and the secondary kidney damage produces diabetic nephropathy (DN). Early nephropathy is defined as the presence of microalbuminuria (30-300 mg/day), including normal glomerular filtration rate (GFR) or a mildly decreased GFR (60-89 mL/min/1.73 m(2)), with or without overt nephropathy. The earliest change caused by DN is hyperfiltration with proteinuria. The acceptable excretion rate of albumin in urine is <30 mg/day. Albuminuria represents the excretion of >300 mg/day. Chronic kidney disease (CKD) is characterized by abnormalities in renal function that persist for >3 months with health implications. Alterations in the redox state in DN are caused by the persistent state of hyperglycemia and the increase in advanced glycation end products (AGEs) with ability to affect the renin-angiotensin system and the transforming growth factor-beta (TGF-β), producing chronic inflammation and glomerular and tubular hypertrophy and favoring the appearance of oxidative stress. In DN imbalance between prooxidant/antioxidant processes exists with an increase in reactive oxygen species (ROS). The overproduction of ROS diminishes expression of the antioxidant enzymes (manganese superoxide dismutase, glutathione peroxidase, and catalase). The early detection of CKD secondary to DN and the timely identification of patients would permit decreasing its impact on health.

Topics: Albuminuria; Catalase; Diabetic Nephropathies; Early Diagnosis; Glutathione Peroxidase; Glycation End Products, Advanced; Humans; Oxidative Stress; Reactive Oxygen Species; Renal Insufficiency, Chronic; Renin-Angiotensin System; Superoxide Dismutase; Transforming Growth Factor beta

Renal fibrosis is a common irreversible process of chronic kidney disease (CKD) characterized by uncontrolled deposits of extracellular matrix, replacement of cellular parenchyma and progressive loss of renal function. Recent evidence suggests that a series of phenotypic transformations of resident renal cells are responsible for the formation of interstitial myofibroblasts, cells that play a key role in the fibrotic process. In the renal glomerulus transformation of mesangial cells to myofibroblasts is an event that orchestrates glomerulosclerosis and the participation of other cells types has also been suggested. Recent findings clarify the role of tubular epithelium in mediating the generation of ECM producing cells in the tubule interstitium. Also, crosstalk between injured cells and myofibroblasts for amplification of the fibrogenic cascade in CKD occurs. The crucial conductor of these changes in the kidney is the transforming growth factor-β (TGF-β). Thus, this review focuses on the control of this cytokines signaling mechanisms and their dysregulation in CKD. Further, some of the promising interventional alternatives targeting TGF-β are also discussed.

Topics: Animals; Fibrosis; Humans; Kidney Tubules; Myofibroblasts; Renal Insufficiency, Chronic; Signal Transduction; Transforming Growth Factor beta

Hypertension and hyperglycaemia are major risk factors that result in chronic kidney disease (CKD). Achievement of blood pressure goals, optimal control of blood glucose levels and the use of agents to block the renin-angiotensin-aldosterone system slow the progression of CKD. However, not all patients are benefited by these interventions and novel strategies to arrest or reverse the pathological processes inherent in CKD are needed. The therapeutic potential of targeting KCa3.1 in CKD will be discussed in this review.. Blockade of KCa3.1 ameliorates activation of renal fibroblasts in diabetic mice by inhibiting the transforming growth factor-β1/small mothers against decapentaplegic pathway. A concomitant reduction in nuclear factor-κB activation in human proximal tubular cells under diabetic conditions has been observed. Advanced glycosylated endproducts induce both protein expression and current density of KCa3.1, which, in turn, mediates migration and proliferation of vascular smooth muscle cells via Ca²⁺-dependent signalling pathways.. Studies have clearly demonstrated a causal role of chronic hyperglycaemia and hypertension in the development of CKD. However, a large proportion of patients develop end-stage kidney disease despite strict glycaemic control and the attainment of recommended blood pressure goals. Therefore, it is essential to identify and validate novel targets to reduce the development and progression of CKD. Recent findings demonstrate that genetic deletion or pharmacologic inhibition of KCa3.1 significantly reduces the development of diabetic nephropathy in animal models. However, the consequences of blockade of KCa3.1 in preventing and treating established diabetic nephropathy in humans warrants further study.

Topics: Cell Movement; Cell Proliferation; Diabetic Nephropathies; Fibroblasts; Glycation End Products, Advanced; Humans; Hypertension; Intermediate-Conductance Calcium-Activated Potassium Channels; Muscle, Smooth, Vascular; NF-kappa B; Renal Insufficiency, Chronic; Signal Transduction; Smad Proteins; Transforming Growth Factor beta

Chronic kidney disease (CKD) is becoming a worldwide epidemic, driven largely by the dramatic rise in the prevalence of diabetes and obesity. Novel targets and treatments for CKD are, therefore, desperately needed-to both mitigate the burden of this disease in the general population and reduce the necessity for renal replacement therapy in individual patients. This Review highlights new insights into the mechanisms that contribute to CKD, and approaches that might facilitate the development of disease-arresting therapies for CKD. Particular focus is given to therapeutic approaches using antifibrotic agents that target the transforming growth factor β superfamily. In addition, we discuss new insights regarding the roles of vascular calcification, the NADPH oxidase family, and inflammation in the pathogenesis of CKD. We also highlight a new understanding regarding kidney energy sensing pathways (AMPK, sirtuins, and mTOR) in a variety of kidney diseases and how they are linked to inflammation and fibrosis. Finally, exciting new insights have been made into the role of mitochondrial function and mitochondrial biogenesis in relation to progressive kidney disease. Prospective therapeutics based on these findings will hopefully renew hope for clinicians and patients in the near future.

Topics: AMP-Activated Protein Kinases; Animals; Anti-Inflammatory Agents; Diabetes Mellitus, Type 1; Diabetes Mellitus, Type 2; Disease Progression; Fibroblast Growth Factor-23; Fibroblast Growth Factors; Fibrosis; Glucuronidase; Humans; Klotho Proteins; Mitochondria; Models, Animal; NADPH Oxidases; NF-kappa B; Renal Insufficiency, Chronic; Transforming Growth Factor beta; Vascular Calcification

All types of progressive chronic kidney disease (CKD) inevitably induce renal fibrosis, the hallmark of which is the activation and accumulation of a large number of matrix-producing fibroblasts or myofibroblasts. The activated fibroblasts or myofibroblasts are derived from diverse origins, such as residential fibroblasts, vascular pericytes, epithelial-to-mesenchymal transition (EMT), and bone marrow (circulating fibrocytes). Recently, endothelial-to-mesenchymal transition (EndMT) or endothelial-to-myofibroblast transition has also been suggested to promote fibrosis and is recognized as a novel mechanism for the generation of myofibroblasts. Similar to EMT, during EndMT, endothelial cells lose their adhesion and apical-basal polarity to form highly invasive, migratory, spindle-shaped, elongated mesenchymal cells. More importantly, biochemical changes accompany these distinct changes in cell polarity and morphology, including the decreased expression of endothelial markers and the acquisition of mesenchymal markers. This review highlights evidence supporting the important role of EndMT in the development of renal fibrosis in CKD and its underlying mechanisms, including novel biological significance of microRNA regulation.

Topics: Disease Progression; Endothelial Cells; Epithelial-Mesenchymal Transition; Fibrosis; Humans; Kidney; Kidney Diseases; Myofibroblasts; Renal Insufficiency, Chronic; Transforming Growth Factor beta

Biomarkers are a useful tool for the investigation of chronic kidney disease (CKD), although the design, analytical tools and outcomes used in many biomarker studies are suboptimal. In part, this situation might reflect a lack of appreciation of the nature of different biomarkers. A particular biomarker could, for example, be implicated in the pathogenesis of CKD because it is a physiological risk factor for declining kidney function, an indicator of impaired kidney function, or a marker of ongoing injury within the kidney. Such risk factors enable us to understand the process of disease and to identify treatment targets. By contrast, risk markers enable us to distinguish persons who will or will not develop CKD, even though the markers themselves are not required to be modifiable by (or directly involved in) the disease process. Accurate prediction of CKD risk will probably require a combination of biomarkers of several types, however. This Review offers a conceptual framework for interpreting the results of studies evaluating biomarkers of declining kidney function and incident CKD.

Topics: Acute-Phase Proteins; Aldosterone; Biomarkers; Connective Tissue Growth Factor; Creatinine; Cystatin C; Genetic Markers; Genetic Predisposition to Disease; Glomerular Filtration Rate; Hepatitis A Virus Cellular Receptor 1; Homocysteine; Humans; Lipocalin-2; Lipocalins; Membrane Glycoproteins; Peptides; Proto-Oncogene Proteins; Receptors, Virus; Renal Insufficiency, Chronic; Risk Factors; Transforming Growth Factor beta; Trefoil Factor-3; Uromodulin

TGF-β (transforming growth factor-β) and BMP-7 (bone morphogenetic protein-7), two key members in the TGF-β superfamily, play important but diverse roles in CKDs (chronic kidney diseases). Both TGF-β and BMP-7 share similar downstream Smad signalling pathways, but counter-regulate each other to maintain the balance of their biological activities. During renal injury in CKDs, this balance is significantly altered because TGF-β signalling is up-regulated by inducing TGF-β1 and activating Smad3, whereas BMP-7 and its downstream Smad1/5/8 are down-regulated. In the context of renal fibrosis, Smad3 is pathogenic, whereas Smad2 and Smad7 are renoprotective. However, this counter-balancing mechanism is also altered because TGF-β1 induces Smurf2, a ubiquitin E3-ligase, to target Smad7 as well as Smad2 for degradation. Thus overexpression of renal Smad7 restores the balance of TGF-β/Smad signalling and has therapeutic effect on CKDs. Recent studies also found that Smad3 mediated renal fibrosis by up-regulating miR-21 (where miR represents microRNA) and miR-192, but down-regulating miR-29 and miR-200 families. Therefore restoring miR-29/miR-200 or suppressing miR-21/miR-192 is able to treat progressive renal fibrosis. Furthermore, activation of TGF-β/Smad signalling inhibits renal BMP-7 expression and BMP/Smad signalling. On the other hand, overexpression of renal BMP-7 is capable of inhibiting TGF-β/Smad3 signalling and protects the kidney from TGF-β-mediated renal injury. This counter-regulation not only expands our understanding of the causes of renal injury, but also suggests the therapeutic potential by targeting TGF-β/Smad signalling or restoring BMP-7 in CKDs. Taken together, the current understanding of the distinct roles and mechanisms of TGF-β and BMP-7 in CKDs implies that targeting the TGF-β/Smad pathway or restoring BMP-7 signalling may represent novel and effective therapies for CKDs.

Topics: Apoptosis; Biomarkers; Bone Morphogenetic Protein 7; Cell Proliferation; Fibrosis; Humans; Renal Agents; Renal Insufficiency, Chronic; Smad Proteins; Transforming Growth Factor beta

Tubulointerstitial fibrosis mediates the development of end-stage renal disease from renal injuries of all etiologies and is considered an important predictor of renal survival. Transforming growth factor-β (TGF-β) is one of the most important growth factors that promotes tubulointerstitial fibrosis, but the mechanisms whereby this occurs are not well defined. This is because TGF-β has pleiotropic effects that depend on the target cell type. This review discusses how TGF-β signaling in each of the relevant cell types (eg, tubular epithelium, fibroblasts) may contribute to tubulointerstitial fibrosis progression and suggests ways in which future research can improve our understanding of TGF-β-mediated tubulointerstitial fibrosis.

Topics: Acute Kidney Injury; Endothelium; Epithelium; Extracellular Matrix; Fibroblasts; Fibrosis; Humans; Kidney; Kidney Failure, Chronic; Kidney Tubules; Renal Insufficiency, Chronic; Signal Transduction; Transforming Growth Factor beta

Transforming growth factor-β (TGF-β) is a multifunctional regulatory cytokine that is implicated in a variety of kidney diseases, including diabetic nephropathy and chronic transplant rejection, where it promotes stimulation of the extracellular matrix deposition, cell proliferation, and migration. TGF-β exerts its biological functions largely via its downstream complex signaling molecules, Smad proteins. Paradoxically, TGF-β also is essential for normal homeostasis and suppression of inflammation through mechanisms that are yet to be fully elucidated. One feasible mechanism by which TGF-β may exert its beneficial properties is through induction of heme oxygenase-1 (HO-1). Induction of this redox-sensitive enzyme is known to be cytoprotective through its potent antioxidant, anti-inflammatory, and anti-apoptotic properties in different conditions including several kidney diseases. In this overview, recent advances in our understanding of the role of TGF-β in kidney disease, its molecular regulation of HO-1 expression, and the potential role of HO-1 induction as a therapeutic modality in TGF-β-mediated kidney diseases are highlighted.

Topics: Acute Kidney Injury; Animals; Extracellular Matrix; Fibrosis; Gene Expression Regulation; Graft Rejection; Heme Oxygenase-1; Humans; Kidney; Kidney Diseases; Mice; Renal Insufficiency, Chronic; Signal Transduction; Smad Proteins; Transforming Growth Factor beta; Transforming Growth Factor beta1; Up-Regulation

The transforming growth factor-β (TGF-β) family comprises more than 30 family members that are structurally related secreted dimeric cytokines, including TGF-β, activins, and bone morphogenetic proteins/growth and differentiation factors. TGF-β are pluripotent regulators of cell proliferation, differentiation, apoptosis, migration, and adhesion of many different cell types. TGF-β pathways are highly evolutionarily conserved and control embryogenesis, tissue repair, and tissue homeostasis in invertebrates and vertebrates. Aberrations in TGF-β activity and signaling underlie a broad spectrum of developmental disorders and major pathologies in human beings, including cancer, fibrosis, and autoimmune diseases. Recent observations have indicated an emerging role for TGF-β in the regulation of mitochondrial bioenergetics and oxidative stress responses characteristic of chronic degenerative diseases and aging. Conversely, energy and metabolic sensory pathways cross-regulate mediators of TGF-β signaling. Here, we review TGF-β and regulation of bioenergetic and mitochondrial functions, including energy and oxidant metabolism and apoptotic cell death, as well as their emerging relevance in renal biology and disease.

Topics: AMP-Activated Protein Kinases; Animals; Apoptosis; DNA, Mitochondrial; Energy Metabolism; Fibrosis; Humans; Kidney; Mice; Mitochondria; Oxidative Stress; Rats; Reactive Oxygen Species; Renal Insufficiency, Chronic; Signal Transduction; Sirtuin 1; Smad Proteins; Transforming Growth Factor beta

The thiazolidinediones are agonists for peroxisome proliferator-activated receptor-gamma, and promote insulin sensitization and improve dyslipidemia in patients with type II diabetes mellitus. Peroxisome proliferator-activated receptor-gamma transduces its actions by binding to common consensus response elements called peroxisome proliferator-activated receptor-response elements, thus modifying expression of numerous genes. Peroxisome proliferator-activated receptor-gamma is widely expressed, including in macrophages and vascular smooth muscle cells. I will review recent novel insights into peroxisome proliferator-activated receptor-gamma agonist actions.. The thiazolidinediones have beneficial effects in humans with type II diabetes related in part to improvement of dysmetabolic syndrome, and also have beneficial effects on progressive renal damage in animal models of diabetic nephropathy and in models with severe hyperlipidemia. Peroxisome proliferator-activated receptor-gamma agonists also have direct benefits on progressive renal injury independent of altering the dysmetabolic profile.. We will review selected evidence of actions of peroxisome proliferator-activated receptor-gamma agonists beyond metabolism, focusing on experimental work, and examine interactions with other key profibrotic mediators, including transforming growth factor-beta and the renin-angiotensin system.

Topics: Animals; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Disease Models, Animal; Disease Progression; Humans; Hypoglycemic Agents; PPAR gamma; Renal Insufficiency, Chronic; Renin-Angiotensin System; Thiazolidinediones; Transforming Growth Factor beta

The pathogenic mechanisms that lead to chronic kidney disease (CKD) converge on a common pathway that results in progressive interstitial fibrosis, peritubular capillary loss with hypoxia, and destruction of functioning nephrons because of tubular atrophy. Interstitial recruitment of inflammatory leukocytes and myofibroblasts occurs early in kidneys destined to develop fibrosis. Circulating monocytes are recruited by locally secreted chemoattractant molecules, facilitated by leukocyte adhesion molecules. Functionally heterogeneous macrophages secrete many fibrosis-promoting molecules, but under some circumstances they may also serve a protective scavenging role. Excessive extracellular matrix production occurs primarily within interstitial myofibroblasts, a population of cells that appears to have more than 1 origin, including the resident interstitial fibroblasts, trans-differentiated tubular epithelial cells, and bone marrow-derived cells. Impaired activity of the endogenous renal matrix-degrading proteases may enhance interstitial matrix accumulation, but the specific pathways that are involved remain unclear. Tubules, inflammatory cells, and myofibroblasts synthesize the molecules that activate the fibrogenic cascades, the most important of which is transforming growth factor beta (TGF-beta). TGF-beta may direct cells to assume a pro-fibrotic phenotype or it may do so indirectly after stimulating synthesis of other fibrogenic molecules such as connective tissue growth factor and plasminogen activator inhibitor-1. Reduced levels of antifibrotic factors that are normally produced in the kidney such as hepatocyte growth factor and bone morphogenic protein-7 may accelerate fibrosis and its destructive consequences. Development of new therapeutic agents for CKD looks promising, but several agents that target different components of the fibrogenic cascade will almost certainly be necessary.

Topics: Apoptosis; Child; Disease Progression; Extracellular Matrix; Fibroblasts; Fibrosis; Humans; Inflammation; Kidney; Renal Insufficiency, Chronic; Transforming Growth Factor beta

Atrial fibrillation (AF) is the most common sustained arrhythmia in patients with chronic kidney disease (CKD). In this study, we examined the association between inflammation and AF in 3,762 adults with CKD, enrolled in the Chronic Renal Insufficiency Cohort (CRIC) study. AF was determined at baseline by self-report and electrocardiogram (ECG). Plasma concentrations of interleukin(IL)-1, IL-1 Receptor antagonist, IL-6, tumor necrosis factor (TNF)-α, transforming growth factor-β, high sensitivity C-Reactive protein, and fibrinogen, measured at baseline. At baseline, 642 subjects had history of AF, but only 44 had AF in ECG recording. During a mean follow-up of 3.7 years, 108 subjects developed new-onset AF. There was no significant association between inflammatory biomarkers and past history of AF. After adjustment for demographic characteristics, comorbid conditions, laboratory values, echocardiographic variables, and medication use, plasma IL-6 level was significantly associated with presence of AF at baseline (Odds ratio [OR], 1.61; 95% confidence interval [CI], 1.21 to 2.14; P = 0.001) and new-onset AF (OR, 1.25; 95% CI, 1.02 to 1.53; P = 0.03). To summarize, plasma IL-6 level is an independent and consistent predictor of AF in patients with CKD.

Topics: Adult; Aged; Atrial Fibrillation; C-Reactive Protein; Electrocardiography; Female; Follow-Up Studies; Humans; Interleukin 1 Receptor Antagonist Protein; Interleukin-6; Male; Middle Aged; Renal Insufficiency, Chronic; Risk Factors; Transforming Growth Factor beta; Tumor Necrosis Factor-alpha

Systemic iron metabolism is disrupted in chronic kidney disease (CKD). However, little is known about local kidney iron homeostasis and its role in kidney fibrosis. Kidney-specific effects of iron therapy in CKD also remain elusive. Here, we elucidate the role of macrophage iron status in kidney fibrosis and demonstrate that it is a potential therapeutic target. In CKD, kidney macrophages exhibited depletion of labile iron pool (LIP) and induction of transferrin receptor 1, indicating intracellular iron deficiency. Low LIP in kidney macrophages was associated with their defective antioxidant response and proinflammatory polarization. Repletion of LIP in kidney macrophages through knockout of ferritin heavy chain (Fth1) reduced oxidative stress and mitigated fibrosis. Similar to Fth1 knockout, iron dextran therapy, through replenishing macrophage LIP, reduced oxidative stress, decreased the production of proinflammatory cytokines, and alleviated kidney fibrosis. Interestingly, iron markedly decreased TGF-β expression and suppressed TGF-β-driven fibrotic response of macrophages. Iron dextran therapy and FtH suppression had an additive protective effect against fibrosis. Adoptive transfer of iron-loaded macrophages alleviated kidney fibrosis, validating the protective effect of iron-replete macrophages in CKD. Thus, targeting intracellular iron deficiency of kidney macrophages in CKD can serve as a therapeutic opportunity to mitigate disease progression.

Topics: Dextrans; Fibrosis; Humans; Iron; Iron Deficiencies; Iron-Dextran Complex; Kidney; Macrophages; Renal Insufficiency, Chronic; Transforming Growth Factor beta

To analyze the dynamic changes of renal function longitudinally and investigate the cytokine profiles at 6 months in patients with Omicron COVID-19. Forty-seven patients with a proven diagnosis of Omicron COVID-19 from January to February 2022 attended a 6-month follow-up after discharge at Tianjin First Central Hospital. The demographic parameters, clinical features, and laboratory indexes were collected during hospitalization and 6 months after discharge. The serum cytokine levels at 6 months were also assessed. Patients were grouped according to with or without kidney involvement at admission. The levels of serum creatinine and estimated glomerular filtration rate (eGFR) were all normal both in the hospital and at follow-up. Whereas, compared with renal function in the hospital, serum creatinine levels at 6 months increased remarkably; meanwhile, eGFR decreased significantly in all patients. The serum levels of interleukin (IL)-2, IL-4, IL-5, IL-6, IL-10, and TNF-α and IFN-γ significantly decreased and TGF-β remarkably increased in the kidney involvement group. The serum levels of IL-2 and IL-5 were positively correlated with age; contrarily, TGF-β showed a negative correlation with aging. The younger was an independent risk factor of the higher TGF-β levels. Omicron patients showed a decline in renal function at follow-up, reflecting the trend of CKD. Serum cytokine profiles were characterized with the majority of cytokines decreased and TGF-β increased in the kidney involvement group; the latter may be used as a sign of CKD. The tendency of CKD is one of the manifestations of long COVID and deserves attention.

Topics: COVID-19; Creatinine; Cytokines; Glomerular Filtration Rate; Humans; Interleukin-5; Kidney; Post-Acute COVID-19 Syndrome; Renal Insufficiency, Chronic; Transforming Growth Factor beta

Topics: Acute Kidney Injury; Animals; Clodronic Acid; Cytokines; Fibrosis; Interleukin-10; Liposomes; Macrophages; Mice; Mice, Inbred C57BL; Renal Insufficiency, Chronic; Reperfusion Injury; Transforming Growth Factor beta

TGFβ1 is a major profibrotic mediator in chronic kidney disease (CKD). Its direct inhibition, however, is limited by adverse effects. Inhibition of activins, also members of the TGFβ superfamily, blocks TGFβ1 profibrotic effects, but the mechanism underlying this and the specific activin(s) involved are unknown.. Cells were treated with TGFβ1 or activins A/B. Activins were inhibited generally with follistatin, or specifically with neutralizing antibodies or type I receptor downregulation. Cytokine levels, signaling and profibrotic responses were assessed with ELISA, immunofluorescence, immunoblotting and promoter luciferase reporters. Wild-type or TGFβ1-overexpressing mice with unilateral ureteral obstruction (UUO) were treated with an activin A neutralizing antibody.. In primary mesangial cells, TGFβ1 induces secretion primarily of activin A, which enables longer-term profibrotic effects by enhancing Smad3 phosphorylation and transcriptional activity. This results from lack of cell refractoriness to activin A, unlike that for TGFβ1, and promotion of TGFβ type II receptor expression. Activin A also supports transcription through regulating non-canonical MRTF-A activation. TGFβ1 additionally induces secretion of activin A, but not B, from tubular cells, and activin A neutralization prevents the TGFβ1 profibrotic response in renal fibroblasts. Fibrosis induced by UUO is inhibited by activin A neutralization in wild-type mice. Worsened fibrosis in TGFβ1-overexpressing mice is associated with increased renal activin A expression and is inhibited to wild-type levels with activin A neutralization.. Activin A facilitates TGFβ1 profibrotic effects through regulation of both canonical (Smad3) and non-canonical (MRTF-A) signaling, suggesting it may be a novel therapeutic target for preventing fibrosis in CKD.

Topics: Activins; Animals; Fibrosis; Mice; Renal Insufficiency, Chronic; Transforming Growth Factor beta

Fibroblast growth factor 23 (FGF23) is associated with cardiovascular disease in patients with chronic kidney disease; however, the mechanisms underlying the effect of FGF23 on cardiac function remain to be investigated. Herein, we studied the effect of continuous intravenous (CIV) FGF23 loading in a deoxycorticosterone acetate (DOCA)-salt mouse model with mild chronic kidney disease and hypertension as well as heart failure with a preserved ejection fraction. Wild-type male mice were randomly allocated to 4 groups: normal control, vehicle-treated DOCA-salt mice, FGF23-treated DOCA-salt mice, and FGF23- and calcitriol-treated DOCA-salt mice. The DOCA-salt mice received the agents via the CIV route for 10 days using an infusion minipump. DOCA-salt mice that received FGF23 showed a marked increase in the serum FGF23 level, and echocardiography in these mice revealed heart failure with a preserved ejection fraction. These mice also showed exacerbation of myocardial fibrosis, concomitant with an inverse and significant correlation with Cyp27b1 expression. Calcitriol treatment attenuated FGF23-induced cardiac fibrosis and improved diastolic function via inhibition of transforming growth factor-β signaling. This effect was independent of the systemic and local levels of FGF23. These results suggest that CIV FGF23 loading exacerbates cardiac fibrosis and that locally abnormal vitamin D metabolism is involved in this mechanism. Calcitriol attenuates this exacerbation by mediating transforming growth factor-β signaling independently of the FGF23 levels.

Topics: Animals; Blood Pressure; Calcitriol; Desoxycorticosterone Acetate; Fibroblast Growth Factor-23; Fibrosis; Heart Failure; Hypertension; Male; Mice; Renal Insufficiency, Chronic; Transforming Growth Factor beta; Transforming Growth Factors

Renal fibrosis is one of the main pathophysiological processes underlying the progression of chronic kidney disease and kidney allograft failure. In the past decades, overwhelming efforts have been undertaken to find druggable targets for the treatment of renal fibrosis, mainly using cell- and animal models. However, the latter often do not adequately reflect human pathogenesis, obtained results differ per strain within a given species, and the models are associated with considerable discomfort for the animals. Therefore, the objective of this study is to implement the 3Rs in renal fibrosis research by establishing an animal-free drug screening platform for renal fibrosis based on human precision-cut kidney slices (PCKS) and by limiting the use of reagents that are associated with significant animal welfare concerns.. Using Western blotting and gene expression arrays, we show that transforming growth factor-β (TGF-β) induced fibrosis in human PCKS. In addition, our results demonstrated that butaprost, SC-19220 and tamoxifen - all putative anti-fibrotic compounds - altered TGF-β-induced pro-fibrotic gene expression in human PCKS. Moreover, we observed that all compounds modulated fairly distinct sets of genes, however they all impacted TGF-β/SMAD signaling. In conclusion, this study revealed that it is feasible to use an animal-free approach to test drug efficacy and elucidate mechanisms of action.

Topics: Animal Testing Alternatives; Animals; Drug Evaluation, Preclinical; Fibrosis; Humans; Kidney; Kidney Diseases; Renal Insufficiency, Chronic; Transforming Growth Factor beta

Kidney-derived thrombopoietin (TPO) increases myeloid cell and platelet production during antibody-mediated chronic kidney disease (AMCKD) in a mouse model, exacerbating chronic thromobinflammation in microvessels. The effect is mirrored in patients with extracapillary glomerulonephritis associated with thromboinflammation, TGF β -dependent glomerulosclerosis, and increased bioavailability of TPO. Neutralization of TPO in mice normalized hematopoiesis, reduced chronic thromboinflammation, and ameliorated renal disease. The findings suggest that TPO is a relevant biomarker and a promising therapeutic target for patients with CKD and other chronic thromboinflammatory diseases.Neutralization of TPO in mice normalized hematopoiesis, reduced chronic thromboinflammation, and ameliorated renal disease. The findings suggest that TPO is a relevant biomarker and a promising therapeutic target for patients with CKD and other chronic thromboinflammatory diseases.. Chronic thromboinflammation provokes microvascular alterations and rarefaction, promoting organ dysfunction in individuals with various life-threatening diseases. Hematopoietic growth factors (HGFs) released by the affected organ may sustain emergency hematopoiesis and fuel the thromboinflammatory process.. Using a murine model of antibody-mediated chronic kidney disease (AMCKD) and pharmacological interventions, we comprehensively monitored the response to injury in the circulating blood, urine, bone marrow, and kidney.. Experimental AMCKD was associated with chronic thromboinflammation and the production of HGFs, especially thrombopoietin (TPO), by the injured kidney, which stimulated and skewed hematopoiesis toward myelo-megakaryopoiesis. AMCKD was characterized by vascular and kidney dysfunction, TGF β -dependent glomerulosclerosis, and microvascular rarefaction. In humans, extracapillary glomerulonephritis is associated with thromboinflammation, TGF β -dependent glomerulosclerosis, and increased bioavailability of TPO. Analysis of albumin, HGF, and inflammatory cytokine levels in sera from patients with extracapillary glomerulonephritis allowed us to identify treatment responders. Strikingly, TPO neutralization in the experimental AMCKD model normalized hematopoiesis, reduced chronic thromboinflammation, and ameliorated renal disease.. TPO-skewed hematopoiesis exacerbates chronic thromboinflammation in microvessels and worsens AMCKD. TPO is both a relevant biomarker and a promising therapeutic target in humans with CKD and other chronic thromboinflammatory diseases.

Topics: Animals; Antibodies; Glomerulonephritis; Hematopoiesis; Humans; Inflammation; Kidney; Mice; Receptors, Thrombopoietin; Renal Insufficiency, Chronic; Thromboinflammation; Thrombopoietin; Thrombosis; Transforming Growth Factor beta

Interstitial fibrosis is the key pathological characteristics of chronic kidney diseases (CKD). In this study, we reported that hederagenin (HDG) can effectively improve the renal interstitial fibrosis and its mechanism. We constructed CKD animal models of ischemia reperfusion injury (IRI) and unilateral ureteral obstruction (UUO) respectively to observe the improvement effect of HDG on CKD. The results showed that HDG can effectively improve the pathological structure of kidney and the renal fibrosis in CKD mice. Meanwhile, HDG can also significantly reduce the expression of α-SMA and FN induced by TGF-β in Transformed C3H Mouse Kidney-1 (TCMK1) cells. Mechanistically, we performed transcriptome sequencing on UUO kidneys treated with HDG. By real time PCR screening of the sequencing results, we determined that ISG15 plays an important role in the intervention of HDG in CKD. Subsequently, we knocked-down ISG15 in TCMK1 and found that ISG15 knock-down significantly inhibited TGF-β-induced fibrotic protein expression and JAK/STAT activation. Finally, we performed electrotransfection and used liposomes to transfect ISG15 overexpression plasmids to up-regulate ISG15 in kidney and cells, respectively. We found that ISG15 can aggravate renal tubular cell fibrosis and abolish the protection of HDG on CKD. These results indicated that HDG significantly improves renal fibrosis in CKD by inhibiting ISG15 and its downstream JAK/STAT signaling pathway, which provides a new drug and research target for the subsequent treatment of CKD.

Topics: Animals; Fibrosis; Kidney; Mice; Mice, Inbred C3H; Renal Insufficiency, Chronic; Signal Transduction; Transforming Growth Factor beta; Transforming Growth Factor beta1; Ureteral Obstruction

Transforming growth factor β (TGF-β) is the primary factor that drives fibrosis in most forms of chronic kidney disease. The aim of this study was to identify endogenous regulators of TGF-β signaling and fibrosis. Here, we show that tubulointerstitial fibrosis is aggravated by global deletion of KLF13 and attenuated by adeno-associated virus-mediated KLF13 overexpression in renal tubular epithelial cells. KLF13 recruits a repressor complex comprising SIN3A and histone deacetylase 1 (HDAC1) to the TGF-β target genes, limiting the profibrotic effects of TGF-β. Temporary upregulation of TGF-β induces KLF13 expression, creating a negative feedback loop that triggers the anti-fibrotic effect of KLF13. However, persistent activation of TGF-β signaling reduces KLF13 levels through FBXW7-mediated ubiquitination degradation and HDAC-dependent mechanisms to inhibit KLF13 transcription and offset the anti-fibrotic effect of KLF13. Collectively, our data demonstrate a role of KLF13 in regulating TGF-β signaling and fibrosis.

Topics: Cell Cycle Proteins; Feedback; Fibrosis; Humans; Kidney; Kruppel-Like Transcription Factors; Renal Insufficiency, Chronic; Repressor Proteins; Signal Transduction; Sp1 Transcription Factor; Transforming Growth Factor beta; Transforming Growth Factor beta1

The present investigation was carried out to explore the role of roflumilast, a PDE4 inhibitor, as a potential treatment option for chronic kidney disease. Forty-six male Wistar rats were divided into five groups: Control, Disease control (50 mg/kg Adenine p.o.), Adenine + Roflumilast (0.5, 1 and 1.5 mg/kg, p.o.). Various urinary and serum biomarkers, antioxidant status, histopathology, and protein expression of inflammatory markers were measured to investigate the effects of roflumilast on kidney functions. Adenine was found to elevate the levels of serum creatinine, urea, uric acid, sodium, potassium, chloride, magnesium, and phosphorus and reduce the level of serum calcium. Further, adenine significantly increased the serum TGF-β levels and reduced the anti-oxidant indices. Significant elevation was observed in protein expression of IL-1β, TNF-α, MCP-1, ICAM-1, and Fibronectin. Histopathologically, adenine caused thickening of the glomerular basement membrane, inflammatory cells infiltration, atrophy, and glomeruli deterioration. However, Roflumilast administration (1 mg/kg) remarkably decrease serum creatinine, urea, uric acid, sodium, potassium, chloride, magnesium, phosphorus by 61%, 40%, 44%, 41%, 49%, 58%, 59% and 42% respectively, and increase in calcium by 158%. Moreover, Roflumilast (1 mg/kg) significantly reduced serum TGF-β levels by 50% and elevated anti-oxidant indices by 257%, 112%, and 60%, respectively. The protein expression was significantly reduced by 5.5-fold, 7-fold, 5.7-fold, 6.2-fold, and 5.1-fold individually. Roflumilast noticeably improved the structure of glomeruli, tubules, and cellular functioning. The study confirmed that Roflumilast has the potential to ameliorate renal injury by reducing and regulating inflammatory responses.

Topics: Adenine; Animals; Antioxidants; Biomarkers; Calcium; Creatinine; Kidney; Magnesium Chloride; Male; Rats; Rats, Wistar; Renal Insufficiency, Chronic; Transforming Growth Factor beta; Urea; Uric Acid

Renal tubulointerstitial fibrosis is the hallmark of various chronic kidney diseases. Symmetric dimethylarginine (SDMA) is an independent cardiovascular risk factor in patients with chronic kidney diseases, which is mostly excreted through renal tubules. However, the effect of SDMA on kidneys in a pathological condition is currently unknown. In this study, we investigated the role of SDMA in renal tubulointerstitial fibrosis and explored its underlying mechanisms.. Mouse unilateral ureteral obstruction (UUO) and unilateral ischemia-reperfusion injury (UIRI) models were established to study renal tubulointerstitial fibrosis. SDMA was injected into kidneys through ureter retrogradely. TGF-β stimulated human renal epithelial (HK2) cells were used as an in vitro model and treated with SDMA. Signal transducer and activator of transcription-4 (STAT4) was inhibited by berbamine dihydrochloride or siRNA or overexpressed by plasmids in vitro. Masson staining and Western blotting were performed to evaluate renal fibrosis. Quantitative PCR was performed to validate findings derived from RNA sequencing analysis.. We observed that SDMA (from 0.01 to 10 µM) dose-dependently inhibited the expression of pro-fibrotic markers in TGF-β stimulated HK2 cells. Intrarenal administration of SDMA (2.5 µmol/kg or 25 µmol/kg) dose-dependently attenuated renal fibrosis in UUO kidneys. A significant increase in SDMA concentration (from 19.5 to 117.7 nmol/g, p < 0.001) in mouse kidneys was observed after renal injection which was assessed by LC-MS/MS. We further showed that intrarenal administration of SDMA attenuated renal fibrosis in UIRI induced mouse fibrotic kidneys. Through RNA sequencing analysis, we found that the expression of STAT4 was reduced by SDMA in UUO kidneys, which was further confirmed by quantitative PCR and Western blotting analysis in mouse fibrotic kidneys and renal cells. Inhibition of STAT4 by berbamine dihydrochloride (0.3 mg/ml or 3.3 mg/ml) or siRNA reduced the expression of pro-fibrotic markers in TGF-β stimulated HK2 cells. Furthermore, blockage of STAT4 attenuated the anti-fibrotic effect of SDMA in TGF-β stimulated HK2 cells. Conversely, overexpression of STAT4 reversed the anti-fibrotic effect of SDMA in TGF-β stimulated HK2 cells.. Taken together, our study indicates that renal SDMA ameliorates renal tubulointerstitial fibrosis through inhibition of STAT4.

Topics: Animals; Chromatography, Liquid; Fibrosis; Humans; Kidney; Kidney Diseases; Mice; Renal Insufficiency, Chronic; RNA, Small Interfering; STAT4 Transcription Factor; Tandem Mass Spectrometry; Transforming Growth Factor beta; Transforming Growth Factor beta1; Ureteral Obstruction

As a part of natural disease progression, acute kidney injury (AKI) can develop into chronic kidney disease via renal fibrosis and inflammation. LTBP4 (latent transforming growth factor beta binding protein 4) regulates transforming growth factor beta, which plays a role in renal fibrosis pathogenesis. We previously investigated the role of LTBP4 in chronic kidney disease. Here, we examined the role of LTBP4 in AKI.. LTBP4 expression was upregulated in the renal tissues of patients with AKI.. Our study is the first to demonstrate that LTBP4 deficiency increases AKI severity, consequently leading to chronic kidney disease. Potential therapies focusing on LTBP4-associated angiogenesis and LTBP4-regulated DRP1-dependent mitochondrial division are relevant to renal injury.

Topics: Acute Kidney Injury; Animals; Endothelial Cells; Fibrosis; Humans; Inflammation; Kidney; Latent TGF-beta Binding Proteins; Mice; Mice, Inbred C57BL; Mitochondria; Renal Insufficiency, Chronic; Reperfusion Injury; Transforming Growth Factor beta

Excessive TGF-β signaling and mitochondrial dysfunction fuel chronic kidney disease (CKD) progression. However, inhibiting TGF-β failed to impede CKD in humans. The proximal tubule (PT), the most vulnerable renal segment, is packed with giant mitochondria and injured PT is pivotal in CKD progression. How TGF-β signaling affects PT mitochondria in CKD remained unknown. Here, we combine spatial transcriptomics and bulk RNAseq with biochemical analyses to depict the role of TGF-β signaling on PT mitochondrial homeostasis and tubulo-interstitial interactions in CKD. Male mice carrying specific deletion of Tgfbr2 in the PT have increased mitochondrial injury and exacerbated Th1 immune response in the aristolochic acid model of CKD, partly, through impaired complex I expression and mitochondrial quality control associated with a metabolic rewiring toward aerobic glycolysis in the PT cells. Injured S3T2 PT cells are identified as the main mediators of the maladaptive macrophage/dendritic cell activation in the absence of Tgfbr2. snRNAseq database analyses confirm decreased TGF-β receptors and a metabolic deregulation in the PT of CKD patients. This study describes the role of TGF-β signaling in PT mitochondrial homeostasis and inflammation in CKD, suggesting potential therapeutic targets that might be used to mitigate CKD progression.

Topics: Animals; Fibrosis; Humans; Inflammation; Kidney; Male; Mice; Mitochondria; Receptor, Transforming Growth Factor-beta Type II; Renal Insufficiency, Chronic; Signal Transduction; Transforming Growth Factor beta

The sustained release of profibrotic cytokines, mainly transforming growth factor-β (TGF-β), leads to the occurrence of kidney fibrosis and chronic kidney disease (CKD). Connective tissue growth factor (CTGF) appears to be an alternative target to TGF-β for antifibrotic therapy in CKD. In this study, we found that long noncoding RNA AI662270 was significantly increased in various renal fibrosis models. In vivo, ectopic expression of AI662270 alone was sufficient to activate interstitial fibroblasts and drive kidney fibrosis, whereas inhibition of AI662270 blocked the activation of interstitial fibroblasts and ameliorated kidney fibrosis in various murine models. Mechanistic studies revealed that overexpression of AI662270 significantly increased CTGF product, which was required for the role of AI662270 in driving kidney fibrosis. Furthermore, AI662270 binds to the CTGF promoter and directly interacts with METTL3, the methyltransferase of RNA N

Topics: Animals; Connective Tissue Growth Factor; Kidney; Methyltransferases; Mice; Renal Insufficiency, Chronic; RNA, Long Noncoding; RNA, Messenger; Transforming Growth Factor beta

Tubulointerstitial fibrosis is considered the final convergent pathway of progressive chronic kidney diseases (CKD) regardless of etiology. However, mechanisms underlying kidney injury-induced fibrosis largely remain unknown. Recent studies have indicated that transcriptional intermediary factor 1γ (TIF1γ) inhibits the progression of fibrosis in other organs. Here, we found that TIF1γ was highly expressed in the cytoplasm and nucleus of the kidney proximal tubule. Interestingly, we found tubular TIF1γ expression was decreased in patients with CKD, including those with diabetes, hypertension, and IgA nephropathy, and in mouse models with experimental kidney fibrosis (unilateral ureteral obstruction [UUO], folic acid nephropathy [FAN], and aristolochic acid-induced nephrotoxicity). Tubule-specific knock out of TIF1γ in mice exacerbated UUO- and FAN-induced tubular cell polyploidy and subsequent fibrosis, whereas overexpression of kidney TIF1γ protected mice against kidney fibrosis. Mechanistically, in tubular epithelial cells, TIF1γ exerted an antifibrotic role via transforming growth factor-β (TGF-β)-dependent and -independent signaling. TIF1γ hindered TGF-β signaling directly by inhibiting the formation and activity of the transcription factor Smad complex in tubular cells, and we discovered that TIF1γ suppressed epidermal growth factor receptor (EGFR) signaling upstream of TGF-β signaling in tubular cells by ubiquitylating EGFR at its lysine 851/905 sites thereby promoting EGFR internalization and lysosomal degradation. Pharmacological inhibition of EGFR signaling attenuated exacerbated polyploidization and the fibrotic phenotype in mice with tubule deletion of TIF1γ. Thus, tubular TIF1γ plays an important role in kidney fibrosis by suppressing profibrotic EGFR and TGF-β signaling. Hence, our findings suggest that maintaining homeostasis of tubular TIF1γ may be a new therapeutic option for treating tubulointerstitial fibrosis and subsequent CKD.

Topics: Animals; Epithelial Cells; ErbB Receptors; Fibrosis; Humans; Kidney; Mediation Analysis; Mice; Renal Insufficiency, Chronic; Transforming Growth Factor beta; Transforming Growth Factor beta1; Ureteral Obstruction

Transforming growth factor-β (TGF-β) is the primary factor that drives fibrosis in most, if not all, forms of chronic kidney disease. In kidneys that are obstructed, specific deletion of Sirt2 in renal tubule epithelial cells (TEC) has been shown to aggravate renal fibrosis, while renal tubule specific overexpression of Sirt2 has been shown to ameliorate renal fibrosis. Similarly, specific deletion of Sirt2 in hepatocyte aggravated CCl4-induced hepatic fibrosis. In addition, we have demonstrated that SIRT2 overexpression and knockdown restrain and enhance TGF-β-induced fibrotic gene expression, respectively, in TEC. Mechanistically, SIRT2 reduced the phosphorylation, acetylation, and nuclear localization levels of SMAD2 and SMAD3, leading to inhibition of the TGF-β signaling pathway. Further studies have revealed that that SIRT2 was able to directly interact with and deacetylate SMAD2 at lysine 451, promoting its ubiquitination and degradation. Notably, loss of SMAD specific E3 ubiquitin protein ligase 2 abolishes the ubiquitination and degradation of SMAD2 induced by SIRT2 in SMAD2. Regarding SMAD3, we have found that SIRT2 interact with and deacetylates SMAD3 at lysine 341 and 378 only in the presence of TGF-β, thereby reducing its activation. This study provides initial indication of the anti-fibrotic role of SIRT2 in renal tubules and hepatocytes, suggesting its therapeutic potential for fibrosis.

Topics: Epithelial Cells; Fibrosis; Humans; Lysine; Renal Insufficiency, Chronic; Sirtuin 2; Smad2 Protein; Smad3 Protein; Transforming Growth Factor beta; Transforming Growth Factor beta1

In the follow‑up of hospitalized patients with acute kidney injury (AKI), it has been observed that 15‑30% of these patients progress to develop chronic kidney disease (CKD). Impaired adaptive repair of the kidneys following AKI is a fundamental pathophysiological mechanism underlying renal fibrosis and the progression to CKD. Deficient repair of proximal tubular epithelial cells is a key factor in the progression from AKI to CKD. However, the molecular mechanisms involved in the regulation of fibrotic factor paracrine secretion by injured tubular cells remain incompletely understood. Transcriptome analysis and an ischemia‑reperfusion injury (IRI) model were used to identify the contribution of flavin‑containing monooxygenase 2 (FMO2) in AKI‑CKD. Lentivirus‑mediated overexpression of FMO2 was performed in mice. Functional experiments were conducted using TGF‑β‑induced tubular cell fibrogenesis and paracrine pro‑fibrotic factor secretion. Expression of FMO2 attenuated kidney injury induced by renal IRI, renal fibrosis, and immune cell infiltration into the kidneys. Overexpression of FMO2 not only effectively blocked TGF secretion in tubular cell fibrogenesis but also inhibited aberrant paracrine activation of pro‑fibrotic factors present in fibroblasts. FMO2 negatively regulated TGF‑β‑mediated SMAD2/3 activation by promoting the expression of SMAD ubiquitination regulatory factor 2 (SMURF2) and its nuclear translocation. During the transition from AKI to CKD, FMO2 modulated tubular cell fibrogenesis and paracrine secretion through SMURF2, thereby affecting the outcome of the disease.

Topics: Acute Kidney Injury; Animals; Epithelial Cells; Fibrosis; Flavins; Humans; Kidney; Mice; Mixed Function Oxygenases; Renal Insufficiency, Chronic; Transforming Growth Factor beta; Ubiquitin-Protein Ligases

Kidney fibrosis, characterized by the activation and expansion of the matrix-producing fibroblasts, is the common outcome of chronic kidney disease (CKD). While fibroblast proliferation is well studied in CKD, little is known about the regulation and mechanism of fibroblast depletion. Here, we show that exosomes derived from stressed/injured tubules play a pivotal role in dictating fibroblast apoptosis and fate. When human kidney tubular cells (HK-2) were stimulated with TGF-β1, they produced and released increased amounts of exosomes (TGFβ-Exo), which prevented renal interstitial fibroblasts from apoptosis. In vivo, injections of TGFβ-Exo promoted renal fibroblast survival, whereas blockade of exosome secretion accelerated fibroblast apoptosis in obstructive nephropathy. Proteomics profiling identified the tumor necrosis factor-α-induced protein 8 (TNFAIP8) as a key component enriched in TGFβ-Exo. TNFAIP8 was induced in renal tubular epithelium and enriched in the exosomes from fibrotic kidneys. Knockdown of TNFAIP8 in tubular cells abolished the ability of TGFβ-Exo to prevent fibroblast apoptosis. In vivo, gain- or loss- of TNFAIP8 prevented or aggravated renal fibroblast apoptosis after obstructive injury. Mechanistically, exosomal-TNFAIP8 promoted p53 ubiquitination leading to its degradation, thereby inhibiting fibroblasts apoptosis and inducing their proliferation. Collectively, these results indicate that tubule-derived exosomes play a critical role in controlling the size of fibroblast population during renal fibrogenesis through shuttling TNFAIP8 to block p53 signaling. Strategies to target exosomes may be effective strategies for the therapy of fibrotic CKD.

Topics: Apoptosis Regulatory Proteins; Epithelial Cells; Exosomes; Fibroblasts; Fibrosis; Humans; Kidney; Kidney Tubules; Renal Insufficiency, Chronic; Transforming Growth Factor beta; Tumor Suppressor Protein p53

Renal fibrosis is the final development pathway and the most common pathological manifestation of chronic kidney disease. Epigenetic alteration is a significant intrinsic factor contributing to the development of renal fibrosis. SET domain-containing 2 (SETD2) is the sole histone H3K36 trimethyltransferase, catalysing H3K36 trimethylation. There is evidence that SETD2-mediated epigenetic alterations are implicated in many diseases. However, it is unclear what role SETD2 plays in the development of renal fibrosis.. Kidney tissues from mice as well as HK2 cells were used as research subjects. Clinical databases of patients with renal fibrosis were analysed to investigate whether SETD2 expression is reduced in the occurrence of renal fibrosis. SETD2 and Von Hippel-Lindau (VHL) double-knockout mice were used to further investigate the role of SETD2 in renal fibrosis. Renal tubular epithelial cells isolated from mice were used for RNA sequencing and chromatin immunoprecipitation sequencing to search for molecular signalling pathways and key molecules leading to renal fibrosis in mice. Molecular and cell biology experiments were conducted to analyse and validate the role of SETD2 in the development of renal fibrosis. Finally, rescue experiments were performed to determine the molecular mechanism of SETD2 deficiency in the development of renal fibrosis.. SETD2 deficiency leads to severe renal fibrosis in VHL-deficient mice. Mechanically, SETD2 maintains the transcriptional level of Smad7, a negative feedback factor of the transforming growth factor-β (TGF-β)/Smad signalling pathway, thereby preventing the activation of the TGF-β/Smad signalling pathway. Deletion of SETD2 leads to reduced Smad7 expression, which results in activation of the TGF-β/Smad signalling pathway and ultimately renal fibrosis in the absence of VHL.. Our findings reveal the role of SETD2-mediated H3K36me3 of Smad7 in regulating the TGF-β/Smad signalling pathway in renal fibrogenesis and provide an innovative insight into SETD2 as a potential therapeutic target for the treatment of renal fibrosis.

Topics: Animals; Fibrosis; Histone-Lysine N-Methyltransferase; Humans; Kidney; Mice; Renal Insufficiency, Chronic; Smad Proteins; Transforming Growth Factor beta; Von Hippel-Lindau Tumor Suppressor Protein

Nerve growth factor-induced gene B (Nur77) has been shown to ameliorate several biological processes in chronic diseases, including inflammatory response, cellular proliferation, and metabolism. Chronic kidney disease (CKD) is characterized by tubulointerstitial fibrosis for which no targeted therapies are available as yet. In this study, we performed in vivo and in vitro experiments to demonstrate that Nur77 targets fibrosis signals and attenuates renal tubulointerstitial fibrosis during the aging process. We observed that the TGF-β/Smads signal pathway was significantly suppressed by Nur77, suggesting that Nur77 controlled the activation of key steps in TGF-β/Smads signaling. We further showed that Nur77 interacted with Smad7, the main repressor of nuclear translocation of Smad2/3, and stabilized Smad7 protein homeostasis. Nur77 deficiency resulted in Smad7 degradation, aggravating Smad2/3 phosphorylation, and promoting transcription of its downstream target genes, ACTA2 and collagen I. Our findings demonstrate that Nur77 is a potential therapeutic target for age-related kidney diseases including CKD. Maintenance of Nur77 may be an effective strategy for blocking renal tubulointerstitial fibrosis and improving renal function in the elderly.

Topics: Aging; Animals; Fibrosis; Mice; Mice, Knockout; Nuclear Receptor Subfamily 4, Group A, Member 1; Renal Insufficiency, Chronic; Signal Transduction; Smad Proteins; Transforming Growth Factor beta

Feline autologous mesenchymal stem cells (MSCs) show promise for immunomodulatory activity, but the functional impact of chronic kidney disease (CKD), concurrent immunosuppressive drug administration or infection is unknown. The study objectives compare endogenous cytokine gene expression (interleukin [IL]-6, IL-10, IL-12p40, IL-18 and transforming growth factor beta [TGF-β]) in adipose-derived MSCs (aMSCs) from cats with and without CKD, following in vitro exposure to microbial ligands and treatment with common immunosuppressive drugs.. Previously obtained aMSCs, phenotype CD44. aMSCs isolated from healthy and CKD cats showed no significant differences in gene expression in the five measured cytokines. No significant changes in measured gene expression after drug treatment or microbial ligand stimulation were observed between normal or CKD affected cats. Proinflammatory genes (IL-6, IL-12p40 and IL-18) showed altered expression in aMSCs from both groups when compared with the same cells in standard culture after exposure to methotrexate. Poly I:C altered IL-6 and TGF-β gene expression in aMSCs from both healthy and CKD cats when compared with the same cells in standard culture.. The five genes tested showed no statistical differences between aMSCs from healthy or CKD cats. There was altered cytokine gene expression between the control and treatment groups of both healthy and CKD cats suggesting feline aMSCs have altered function with immunosuppressive treatment or microbial ligand exposure. Although the current clinical relevance of this pilot study comparing brief exposure to select agents in vitro in aMSCs from a small number of cats is unknown, the study highlights a need for continued investigation into the effects of disease and concurrent therapies on use of cell-based therapies in feline patients.

Topics: Adipose Tissue; Animals; Cat Diseases; Cats; Cytokines; Gene Expression; Interleukin-12 Subunit p40; Interleukin-18; Interleukin-6; Ligands; Mesenchymal Stem Cells; Methotrexate; Pharmaceutical Preparations; Pilot Projects; Poly I; Renal Insufficiency, Chronic; Transforming Growth Factor beta

Topics: Adenine; Animals; Artemisinins; Azacitidine; beta Catenin; Biotin; DNA; DNA Modification Methylases; Fibrosis; Glucuronidase; HEK293 Cells; Humans; Kidney; Klotho Proteins; Mice; Proteasome Endopeptidase Complex; Renal Insufficiency, Chronic; Transforming Growth Factor beta; Transforming Growth Factor beta1; Ubiquitins; Ureteral Obstruction

Renal fibrosis is an irreversible and progressive process that causes severe dysfunction in chronic kidney disease (CKD). The progression of CKD stages is highly associated with a gradual reduction in serum Klotho levels. We focused on Klotho protein as a key therapeutic factor against CKD. Urine-derived stem cells (UDSCs) have been identified as a novel stem cell source for kidney regeneration and CKD treatment because of their kidney tissue-specific origin. However, the relationship between UDSCs and Klotho in the kidneys is not yet known. In this study, we discovered that UDSCs were stem cells that expressed Klotho protein more strongly than other mesenchymal stem cells (MSCs). UDSCs also suppressed fibrosis by inhibiting transforming growth factor (TGF)-β in HK-2 human renal proximal tubule cells in an in vitro model. Klotho siRNA silencing reduced the TGF-inhibiting ability of UDSCs. Here, we suggest an alternative cell source that can overcome the limitations of MSCs through the synergetic effect of the origin specificity of UDSCs and the anti-fibrotic effect of Klotho.

Topics: Female; Fibrosis; Glucuronidase; Humans; Kidney; Klotho Proteins; Male; Regeneration; Renal Insufficiency, Chronic; Signal Transduction; Stem Cells; Transforming Growth Factor beta; Transforming Growth Factor beta1; Urine

Renal fibrosis is a chronic pathological process that seriously endangers human health. However, the current therapeutic options for this disease are extremely limited. Previous studies have shown that signaling factors such as JAK2/STAT3, Smad3, and Myd88 play a regulatory role in renal fibrosis, and β-elemene is a plant-derived sesquiterpenoid organic compound that has been shown to have anti-inflammatory, anti-cancer, and immunomodulatory effects. In the present study, the anti-fibrotic effect of β-elemene was demonstrated by in vivo and in vitro experiments. It was shown that β-elemene inhibited the synthesis of extracellular matrix-related proteins in unilateral ureteral obstruction mice, and TGF-β stimulated rat interstitial fibroblast cells, including α-smooth muscle actin, vimentin, and connective tissue growth factor, etc. Further experiments showed that β-elemene reduced the expression levels of the above-mentioned fibrosis-related proteins by blocking the phosphorylation of JAK2/STAT3, Smad3, and the expression or up-regulation of MyD88. Notably, knockdown of MyD88 attenuated the phosphorylation levels of STAT3 and Smad3 in TGF-β stimulated NRK49F cell, which may be a novel molecular mechanism by which β-elemene affects renal interstitial fibrosis. In conclusion, this study elucidated the anti-interstitial fibrosis effect of β-elemene, which provides a new direction for future research and development of drugs related to chronic kidney disease.

Topics: Adaptor Proteins, Signal Transducing; Animals; Cell Line; Fibrosis; Mice; Myeloid Differentiation Factor 88; Rats; Renal Insufficiency, Chronic; Sesquiterpenes; Smad3 Protein; STAT3 Transcription Factor; Transforming Growth Factor beta; Ureteral Obstruction

Clopidogrel, a P2Y12 inhibitor, is a novel anti-fibrosis agent for chronic kidney disease (CKD), but its mechanisms remain unclear, which we investigated by silencing P2Y12 or treating unilateral ureteral obstruction (UUO) in LysM-Cre/Rosa Tomato mice with clopidogrel in vivo and in vitro. We found that P2Y12 was significantly increased and correlated with progressive renal fibrosis in CKD patients and UUO mice. Phenotypically, up to 82% of P2Y12-expressing cells within the fibrosing kidney were of macrophage origin, identified by co-expressing CD68/F4/80 antigens or a macrophage-lineage-tracing marker Tomato. Unexpectedly, more than 90% of P2Y12-expressing macrophages were undergoing macrophage-to-myofibroblast transition (MMT) by co-expressing alpha smooth muscle actin (α-SMA), which was also confirmed by single-cell RNA sequencing. Functionally, clopidogrel improved the decline rate of the estimated glomerular filtration rate (eGFR) in patients with CKD and significantly inhibited renal fibrosis in UUO mice. Mechanistically, P2Y12 expression was induced by transforming growth factor β1 (TGF-β1) and promoted MMT via the Smad3-dependent mechanism. Thus, silencing or pharmacological inhibition of P2Y12 was capable of inhibiting TGF-β/Smad3-mediated MMT and progressive renal fibrosis in vivo and in vitro. In conclusion, P2Y12 is highly expressed by macrophages in fibrosing kidneys and mediates renal fibrosis by promoting MMT via TGF-β/Smad3 signaling. Thus, P2Y12 inhibitor maybe a novel and effective anti-fibrosis agent for CKD.

Topics: Animals; Clopidogrel; Fibrosis; Kidney; Kidney Diseases; Macrophages; Mice; Mice, Inbred C57BL; Myofibroblasts; Renal Insufficiency, Chronic; Signal Transduction; Smad3 Protein; Transforming Growth Factor beta; Transforming Growth Factor beta1; Ureteral Obstruction

Chronic kidney disease (CKD) is a slow-developing, progressive deterioration of renal function. The final common pathway in the pathophysiology of CKD involves glomerular sclerosis, tubular atrophy and interstitial fibrosis. Transforming growth factor-beta (TGF-β) stimulates the differentiation of fibroblasts towards myofibroblasts and the production of extracellular matrix (ECM) molecules, and thereby interstitial fibrosis. It has been shown that endoglin (ENG, CD105), primarily expressed in endothelial cells and fibroblasts, can function as a co-receptor of TGF signaling. In several human organs, endoglin tends to be upregulated when chronic damage and fibrosis is present. We hypothesize that endoglin is upregulated in renal interstitial fibrosis and plays a role in the progression of CKD. We first measured renal endoglin expression in biopsy samples obtained from patients with different types of CKD, i.e., IgA nephropathy, focal segmental glomerulosclerosis (FSGS), diabetic nephropathy (DN) and patients with chronic allograft dysfunction (CAD). We showed that endoglin is upregulated in CAD patients (p < 0.001) and patients with DN (p < 0.05), compared to control kidneys. Furthermore, the amount of interstitial endoglin expression correlated with eGFR (p < 0.001) and the amount of interstitial fibrosis (p < 0.001), independent of the diagnosis of the biopsies. Finally, we investigated in vitro the effect of endoglin overexpression in TGF-β stimulated human kidney fibroblasts. Overexpression of endoglin resulted in an enhanced ACTA2, CCN2 and SERPINE1 mRNA response (p < 0.05). It also increased the mRNA and protein upregulation of the ECM components collagen type I (COL1A1) and fibronectin (FN1) (p < 0.05). Our results suggest that endoglin is an important mediator in the final common pathway of CKD and could be used as a possible new therapeutic target to counteract the progression towards end-stage renal disease (ESRD).

Topics: Diabetic Nephropathies; Endoglin; Endothelial Cells; Fibrosis; Humans; Kidney; Kidney Failure, Chronic; Receptors, Growth Factor; Renal Insufficiency, Chronic; RNA, Messenger; Transforming Growth Factor beta

Renal fibrosis is the main pathological feature of the occurrence and development of chronic nephropathy. At present, there is no effective treatment, except for renal transplantation and dialysis. Previous studies have shown that nano-preparations can be used as a therapeutic tool to target organs. In this study, we studied the therapeutic effect and mechanism of Chinese medicine monomer Gypenoside (Gyp) XLIX on renal fibrosis and explored the targeting and therapeutic effects of polylactic acid-co-glycoside (PLGA)-Gyp XLIX nanoparticles in unilateral ureteral occlusion (UUO) kidney. Gyp XLIX and PLGA-Gyp XLIX nanoparticles were used to treat UUO mice and Human renal tubular epithelial (HK2) cells stimulated by transforming growth factor-β (TGF-β). Histopathological and molecular biological techniques were used to detect the expression of type I collagen and alpha-smooth muscle actin (α-SMA). To investigate the in vivo targeting of PLGA nanoparticles, they were loaded with 1,1-dioctadecyl-3,3,3,3-tetramethylindotricarbocyanine iodide and injected into UUO mice. We evaluated the effect of Gyp XLIX nanoparticles on TGF-β/Smad3 pathway, a central driver for renal fibrosis in Smad-deficient HK2 cells. Fluorescence imaging showed that the PLGA nanoparticles around 120 nm could be targeted to the UUO kidney. Compared with Gyp XLIX, PLGA-Gyp XLIX nanoparticles could effectively inhibit renal fibrosis and reduce collagen deposition and reduce renal tubular necrosis. Gyp XLIX decreased the phosphorylation of Smad3, but could not further reduce the levels of type I collagen and α-SMA in Smad-deficient cells. This study opens a promising way for targeted drug treatment of renal fibrosis.

Topics: Animals; Cell Line; Disease Models, Animal; Drugs, Chinese Herbal; Fibrosis; Gene Knockdown Techniques; Humans; Kidney Tubules; Male; Mice; Nanoparticle Drug Delivery System; Renal Insufficiency, Chronic; Saponins; Signal Transduction; Smad3 Protein; Specific Pathogen-Free Organisms; Transforming Growth Factor beta

The kidney is one of the most susceptible organs to age-related impairments. Generally, renal aging is accompanied by renal fibrosis, which is the final common pathway of chronic kidney diseases. Aristolochic acid (AA), a nephrotoxic agent, causes AA nephropathy (AAN), which is characterized by progressive renal fibrosis and functional decline. Although renal fibrosis is associated with renal aging, whether AA induces renal aging remains unclear. The aim of the present study is to investigate the potential use of AAN as a model of renal aging. Here, we examined senescence-related factors in AAN models by chronically administering AA to C57BL/6 mice. Compared with controls, the AA group demonstrated aging kidney phenotypes, such as renal atrophy, renal functional decline, and tubulointerstitial fibrosis. Additionally, AA promoted cellular senescence specifically in the kidneys, and increased renal p16 mRNA expression and senescence-associated β-galactosidase activity. Furthermore, AA-treated mice exhibited proximal tubular mitochondrial abnormalities, as well as reactive oxygen species accumulation. Klotho, an antiaging gene, was also significantly decreased in the kidneys of AA-treated mice. Collectively, the results of the present study indicate that AA alters senescence-related factors, and that renal fibrosis is closely related to renal aging.

Topics: Aging; Animals; Aristolochic Acids; beta-Galactosidase; Collagen; Cyclin-Dependent Kinase Inhibitor p16; Disease Models, Animal; Fibrosis; Gene Expression Regulation; Humans; Kidney; Klotho Proteins; Male; Mice; Mice, Inbred C57BL; Mitochondria; Nephritis, Interstitial; Reactive Oxygen Species; Renal Insufficiency, Chronic; Signal Transduction; Transforming Growth Factor beta

Lindera aggregata is a main Chinese herb of ancient prescriptions Suoquan pill applied for treating the chronic kidney disease (CKD). A large number of application histories of Lindera aggregata in the treatment of CKD have been recorded in Chinese traditional medical literature. The previous reports revealed that Lindera aggregata can treat CKD.. Rats were randomly divided into control, model, Huangkui,Lindera aggregata ethanol extract (LEE) and Lindera aggregata water extract (LWE) groups. hematoxylin-eosin (HE) staining was used to detect the pathology of kidney. The levels of serum creatinine (Scr), serum Neutrophil gelatinase-associated lipocalin (NGAL), blood urea nitrogen (BUN), urine protein (UP), kidney index(KI) were evaluated. The UPLC - QTOF/MS were applied to probe the metabolic profile. Furthermore, Indoxyl sulfate-induced human renal tubular epithelial (HK-2) cell model was built to determine the expression levels of pathogenesis-related proteins.. The results demonstrated that LEE and LWE significantly inhibited the rebound in Scr, BUN, NGAL, UP and KI in models, except for the effect of LWE at low dose (LWE-L) and LEE at low dose (LEE-L) on KI and the effect of LWE-H at high dose (LWE-H) and LEE-L on BUN and NGAL. Moreover,Lindera aggregata extracts alleviated renal tubular dilatation, interstitial fibrosis and interstitial inflammation. By analysis, twenty-eight metabolites were related to CKD. After intervention of Lindera aggregata extracts, some metabolites approach to a normal-like level, such as Indoxyl sulfate. These metabolites are mainly involved in tryptophan, fatty acid, glycerophospholipid, tyrosine and arachidonic acid metabolic pathways. Furthermore, Lindera aggregata extracts mediate the expression of smad2, smad3, smad7 and TGF-β in Indoxyl sulfate-induced HK-2 cell.. Lindera aggregata extracts can mitigate adenine-induced CKD by modulating the metabolic profile and TGF-β/Smad signaling pathway, providing important supports for developing protective agent of Lindera aggregata for CKD.

Topics: Adenine; Animals; Chromatography, High Pressure Liquid; Drugs, Chinese Herbal; Fibrosis; Humans; Kidney; Kidney Function Tests; Lindera; Male; Mass Spectrometry; Metabolomics; Phytotherapy; Rats; Renal Insufficiency, Chronic; Signal Transduction; Smad Proteins; Transforming Growth Factor beta

Kallistatin is a multiple functional serine protease inhibitor that protects against vascular injury, organ damage and tumor progression. Kallistatin treatment reduces inflammation and fibrosis in the progression of chronic kidney disease (CKD), but the molecular mechanisms underlying this protective process and whether kallistatin plays an endogenous role are incompletely understood. In the present study, we observed that renal kallistatin levels were significantly lower in patients with CKD. It was also positively correlated with estimated glomerular filtration rate (eGFR) and negatively correlated with serum creatinine level. Unilateral ureteral obstruction (UUO) in animals also led to down-regulation of kallistatin protein in the kidney, and depletion of endogenous kallistatin by antibody injection resulted in aggravated renal fibrosis, which was accompanied by enhanced Wnt/β-catenin activation. Conversely, overexpression of kallistatin attenuated renal inflammation, interstitial fibroblast activation and tubular injury in UUO mice. The protective effect of kallistatin was due to the suppression of TGF-β and β-catenin signaling pathways and subsequent inhibition of epithelial-to-mesenchymal transition (EMT) in cultured tubular cells. In addition, kallistatin could inhibit TGF-β-mediated fibroblast activation via modulation of Wnt4/β-catenin signaling pathway. Therefore, endogenous kallistatin protects against renal fibrosis by modulating Wnt/β-catenin-mediated EMT and fibroblast activation. Down-regulation of kallistatin in the progression of renal fibrosis underlies its potential as a valuable clinical biomarker and therapeutic target in CKD.

Topics: Adult; Aged; Animals; beta Catenin; Disease Models, Animal; Female; Fibrosis; Humans; Kidney; Male; Mice, Inbred BALB C; Middle Aged; Rats, Sprague-Dawley; Renal Insufficiency, Chronic; Serpins; Transforming Growth Factor beta; Ureteral Obstruction; Wnt Signaling Pathway

We established a novel mouse model of chronic kidney disease (CKD) using acetic acid and compared it with the 5/6-nephrectomized mouse model. In our novel model, significant increases were observed in blood biochemical values and urinary parameters. Moreover, a decrease in creatinine clearance (Ccr) was observed. This model also demonstrated a higher survival rate than the 5/6-nephrectomized model. Observed histological changes in our model included cell infiltration in the renal interstitium, tubular dilation, regenerated tubules, and glomerulosclerosis. Inflammation of the renal interstitium was particularly remarkable. TNF-α, IL-1β, and ICAM-1 mRNA expression were up-regulated prior to elevation of mean blood pressure and prior to changes in blood biochemical values and urinary parameters. Up-regulation of TGF-β mRNA and down-regulation of nephrin mRNA were also observed at 12 weeks after acetic acid treatment. However, no correlation between the progression of CKD and the decrease in renal blood flow was observed. Finally, repeated losartan administration attenuated the effects of acetic acid-induced renal injury. Our findings suggest that chronic kidney conditions associated with this model may be triggered by interstitial inflammation. Moreover, we suggest that this model is useful for understanding the pathophysiological mechanisms of CKD, and for evaluating the effects of therapeutic agents.

Topics: Acetic Acid; Animals; Creatine; Disease Models, Animal; Gene Expression; Interleukin-1beta; Kidney; Losartan; Male; Membrane Proteins; Metabolic Clearance Rate; Mice, Inbred Strains; Nephrectomy; Renal Insufficiency, Chronic; Transforming Growth Factor beta; Tumor Necrosis Factor-alpha

We aimed to investigate the role of cMet agonistic antibody (cMet Ab) in preventing kidney fibrosis during acute kidney injury (AKI) to chronic kidney disease (CKD) transition. Additionally, we explored the effect of cMet Ab on TGF-β1/Smad pathway during the pathogenesis of kidney fibrosis. A unilateral ischemia-reperfusion injury (UIRI) mouse model was established to induce AKI-to-CKD transition. Furthermore, we incubated human proximal tubular epithelial cells (hPTECs) under hypoxic conditions as in vitro model of kidney fibrosis. We analyzed the soluble plasma cMet level in patients with AKI requiring dialysis. Patients who did not recover kidney function and progressed to CKD presented a higher increase in the cMet level. The kidneys of mice treated with cMet Ab showed fewer contractions and weighed more than the controls. The mice in the cMet Ab-treated group showed reduced fibrosis and significantly decreased expression of fibronectin and α-smooth muscle actin. cMet Ab treatment decreased inflammatory markers (MCP-1, TNF-α, and IL-1β) expression, reduced Smurf1 and Smad2/3 level, and increased Smad7 expressions. cMet Ab treatment increased cMet expression and reduced the hypoxia-induced increase in collagen-1 and ICAM-1 expression, thereby reducing apoptosis in the in vitro cell model. After cMet Ab treatment, hypoxia-induced expression of Smurf1, Smad2/3, and TGF-β1 was reduced, and suppressed Smad7 was activated. Down-regulation of Smurf1 resulted in suppression of hypoxia-induced fibronectin expression, whereas treatment with cMet Ab showed synergistic effects. cMet Ab can successfully prevent fibrosis response in UIRI models of kidney fibrosis by decreasing inflammatory response and inhibiting the TGF-β1/Smad pathway.

Topics: Acute Kidney Injury; Animals; Fibrosis; Humans; Kidney; Mice, Inbred C57BL; Renal Insufficiency, Chronic; Reperfusion Injury; Smad7 Protein; Transforming Growth Factor beta

[Figure: see text].

Topics: Apoptosis; Arterioles; Child; Cytoskeleton; Endothelial Cells; Glucose; Humans; Interleukin-6; Lamins; Peritoneal Dialysis; Peritoneum; Renal Insufficiency, Chronic; Smad Proteins; Tight Junctions; Transforming Growth Factor beta; Vascular Diseases

Persons with chronic kidney disease (CKD) are at high risk of infection. While low-grade inflammation could impair immune response, it is unknown whether inflammatory markers are associated with infection risk in this clinical population. Using 2003-2013 data from the Chronic Renal Insufficiency Cohort Study (3,597 participants with CKD), we assessed the association of baseline plasma levels of 4 inflammatory markers (interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), interleukin-1 receptor antagonist (IL-1RA), and transforming growth factor-β (TGF-β)) with incident hospitalization with major infection (pneumonia, urinary tract infection, cellulitis and osteomyelitis, and bacteremia and sepsis). During follow-up (median 7.5 years), 36% (n = 1,290) had incident hospitalization with major infection. In multivariable Cox analyses with each inflammatory marker modeled as a restricted cubic spline, higher levels of IL-6 and TNF-α were monotonically associated with increased risk of hospitalization with major infection (for 95th vs. 5th percentile, hazard ratio = 2.11 (95% confidence interval: 1.68, 2.66) for IL-6 and 1.88 (95% confidence interval: 1.51, 2.33) for TNF-α), while corresponding associations for IL-1RA or TGF-β were nonsignificant. Thus, higher plasma levels of IL-6 and TNF-α, but not IL-1RA or TGF-β, were significantly associated with increased risk of hospitalization with major infection. Future studies should investigate whether inflammatory pathways that involve IL-6 and TNF-α increase susceptibility to infection among individuals with CKD.

Topics: Adult; Aged; Biomarkers; Disease Susceptibility; Female; Hospitalization; Humans; Incidence; Infections; Inflammation; Interleukin 1 Receptor Antagonist Protein; Interleukin-6; Male; Middle Aged; Prospective Studies; Renal Insufficiency, Chronic; Transforming Growth Factor beta; Tumor Necrosis Factor-alpha

Chronic renal failure (CRF), also known as chronic kidney disease (CKD), is a common renal disorder characterized by gradual kidney dysfunction. Molecular dissection reveals that transforming growth factor beta (TGF-β) plays a central role in the pathogenesis of CRF. However, the mechanism underlying TGF-β upregulation has not been demonstrated. Here, we verified that the elevated level of TGF-β was associated with the severity of CRF stages and the activation of TGF-β-mediated signaling in 120 renal biopsies from CRF patients. By analyzing the promoter region of the

Topics: Blotting, Western; Cell Line; Cell Nucleus; Chromatin Immunoprecipitation; Humans; Immunoprecipitation; Kidney Failure, Chronic; Mass Spectrometry; NF-kappa B; Promoter Regions, Genetic; Protein Binding; Proto-Oncogene Proteins c-fos; Renal Insufficiency, Chronic; Signal Transduction; Transcription Factor AP-1; Transforming Growth Factor beta; Transforming Growth Factor beta1

Progressive tubulointerstitial fibrosis is the common final outcome for all kidney diseases evolving into chronic kidney disease (CKD), whereas molecular mechanisms driving fibrogenesis remain elusive. Retinoic acid-inducible gene-I (RIG-I), an intracellular pattern recognition receptor, is originally identified participating in immune response by recognizing virus RNA. Here, we revealed for the first time that RIG-I was induced in unilateral ureteral obstruction (UUO) and folic acid (FA) renal fibrosis models and moderate-degree renal fibrosis patients. Besides, we found RIG-I was mainly located in renal tubular epithelial cells and promoted the production and release of inflammatory cytokines, such as interleukin (IL)-1β and IL-6 through activation of NF-κB. Inflammatory cytokines released by tubular epithelial cells activated c-Myc-mediated TGF-β/Smad signaling in fibroblasts, which in turn aggravated interstitial fibrosis by promoting fibroblast activation and production of extracellular matrix components (ECM). Deficiency of RIG-I attenuated renal fibrosis by the regulation of inflammatory responses, c-Myc expression, and fibroblast activation. Besides, gene silencing of RIG-I reduced inflammatory cytokines in cultured tubular epithelial cells treated with Angiotensin II. Knockdown of c-Myc or c-Myc inhibitor blocked IL-1β-induced fibroblast activation. Collectively, our study demonstrates that RIG-I plays a significant role in the progress of renal fibrosis via regulating c-Myc-mediated fibroblast activation. KEY MESSAGES: • RIG-I was constantly elevated in kidneys from renal fibrotic mice. • RIG-I facilitated inflammatory cytokine production in tubular epithelial cells. • RIG-I aggravated renal fibrosis via c-Myc-mediated TGF-β/Smad activation.

Topics: Angiotensin II; Animals; Biomarkers; Biopsy; Cytokines; DEAD Box Protein 58; Disease Susceptibility; Fibroblasts; Fibrosis; Gene Silencing; Immunohistochemistry; Inflammation Mediators; Interleukin-1beta; Male; Mice; Proto-Oncogene Proteins c-myc; Renal Insufficiency, Chronic; Smad Proteins; Transforming Growth Factor beta; Ureteral Obstruction

Metabolic syndrome (MetS) profoundly changes the contents of mesenchymal stem cells and mesenchymal stem cells-derived extracellular vesicles (EVs). The anti-inflammatory TGF-β (transforming growth factor-β) is selectively enriched in EVs from Lean but not from MetS pigs, but the functional impact of this endowment remains unknown. We hypothesized that Lean-EVs more effectively induce regulatory T cells in injured kidneys. Five groups of pigs (n=7 each) were studied after 16 weeks of diet-induced MetS and unilateral renal artery stenosis (RAS; MetS+RAS). Two groups of MetS+RAS were treated 4 weeks earlier with an intrarenal injection of either Lean-EVs or MetS-EVs. MetS+RAS had lower renal volume, renal blood flow, and glomerular filtration rate than MetS pigs. Compared with Lean-EVs, MetS-EVs were less effective in improving renal function and decreasing tubular injury and fibrosis in MetS+RAS. Lean-EVs upregulated TGF-β expression in stenotic kidney and increased regulatory T cells numbers more prominently. Furthermore, markedly upregulated anti-inflammatory M2 macrophages reduced proinflammatory M1 macrophages, and CD8

Topics: Animals; Coculture Techniques; Cytokines; Dietary Carbohydrates; Dietary Fats; Extracellular Vesicles; Female; Inflammation; Infusions, Intra-Arterial; Metabolic Syndrome; MicroRNAs; Monocytes; Random Allocation; Renal Artery; Renal Artery Obstruction; Renal Circulation; Renal Insufficiency, Chronic; Signal Transduction; Swine; T-Lymphocytes, Regulatory; Transforming Growth Factor beta

Chronic kidney disease (CKD) accelerates the development of neointima formation at the anastomosis site of arteriovenous (AV) fistulas. Accumulation of certain uremic toxins has a deleterious effect on the cardiovascular system. The oral charcoal adsorbent, AST-120, reduces circulating and tissue uremic toxins, but its effect on neointima formation at an AV fistula is unknown. To understand the effect of CKD and AST-120 on neointima formation, we created AV fistulas (common carotid artery to the external jugular vein in an end-to-side anastomosis) in mice with and without CKD. AST-120 was administered in chow before and after AV fistula creation. Administration of AST-120 significantly decreased serum indoxyl sulfate levels in CKD mice. CKD mice had a larger neointima area than non-CKD mice, and administration of AST-120 in CKD mice attenuated neointima formation. Both smooth muscle cell and fibrin components were increased in CKD mice, and AST-120 decreased both. RNA expression of MMP-2, MMP-9, TNFα, and TGFβ was increased in neointima tissue of CKD mice, and AST-120 administration neutralized the expression. Our results provided in vivo evidence to support the role of uremic toxin-binding therapy on the prevention of neointima formation. Peri-operative AST-120 administration deserves further investigation as a potential therapy to improve AV fistula patency.

Topics: Administration, Oral; Adsorption; Animals; Arteriovenous Shunt, Surgical; Carbon; Collagen; Disease Models, Animal; Graft Occlusion, Vascular; Indican; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Mice, Inbred C57BL; Muscle, Smooth, Vascular; Neointima; Oxides; Renal Insufficiency, Chronic; Toxins, Biological; Transforming Growth Factor beta; Tumor Necrosis Factor-alpha; Uremia; Vascular Patency

Uremic cardiomyopathy, characterized by hypertension, cardiac hypertrophy, and fibrosis, is a complication of chronic kidney disease (CKD). Urea transporter (UT) inhibition increases the excretion of water and urea, but the effect on uremic cardiomyopathy has not been studied. We tested UT inhibition by dimethylthiourea (DMTU) in 5/6 nephrectomy mice. This treatment suppressed CKD-induced hypertension and cardiac hypertrophy. In CKD mice, cardiac fibrosis was associated with upregulation of UT and vimentin abundance. Inhibition of UT suppressed vimentin amount. Left ventricular mass index in DMTU-treated CKD was less compared with non-treated CKD mice as measured by echocardiography. Nephrectomy was performed in UT-A1/A3 knockout (UT-KO) to further confirm our finding. UT-A1/A3 deletion attenuates the CKD-induced increase in cardiac fibrosis and hypertension. The amount of α-smooth muscle actin and tgf-β were significantly less in UT-KO with CKD than WT/CKD mice. To study the possibility that UT inhibition could benefit heart, we measured the mRNA of renin and angiotensin-converting enzyme (ACE), and found both were sharply increased in CKD heart; DMTU treatment and UT-KO significantly abolished these increases. Conclusion: Inhibition of UT reduced hypertension, cardiac fibrosis, and improved heart function. These changes are accompanied by inhibition of renin and ACE.

Topics: Actins; Animals; Cardiomegaly; Cardiomyopathies; Fibrosis; Heart Ventricles; Hypertension; Kidney; Male; Membrane Transport Proteins; Mice; Mice, Inbred C57BL; Peptidyl-Dipeptidase A; Renal Insufficiency, Chronic; RNA, Messenger; Transforming Growth Factor beta; Urea; Urea Transporters

Topics: Animals; Cardiovascular Diseases; Humans; Inflammation; Kidney Failure, Chronic; Muscle, Skeletal; Myostatin; Renal Insufficiency, Chronic; Sarcopenia; Signal Transduction; Transforming Growth Factor beta

The nephrotoxicity of aristolochic acids (AAs), p-cresyl sulfate (PCS) and indoxyl sulfate (IS) were well-documented, culminating in tubulointerstitial fibrosis (TIF), advanced chronic kidney disease (CKD) and fatal urothelial cancer. Nonetheless, information regarding the attenuation of AAs-induced nephropathy (AAN) and uremic toxin retention is scarce. Propolis is a versatile natural product, exerting anti-oxidant, anti-cancer and anti-fibrotic properties. We aimed to evaluate nephroprotective effects of propolis extract (PE) in a murine model. AAN was developed to retain circulating PCS and IS using C57BL/6 mice, mimicking human CKD. The kidney sizes/masses, renal function indicators, plasma concentrations of PCS/IS, tissue expressions of TIF, α-SMA, collagen IaI, collagen IV and signaling pathways in transforming growth factor-β (TGF-β) family were analyzed among the control, PE, AAN, and AAN-PE groups. PE ameliorated AAN-induced renal atrophy, renal function deterioration, TIF, plasma retention of PCS and IS. PE also suppressed α-SMA expression and deposition of collagen IaI and IV in the fibrotic epithelial-mesenchymal transition. Notably, PE treatment in AAN model inhibited not only SMAD 2/3-dependent pathways but also SMAD-independent JNK/ERK activation in the signaling cascades of TGF-β family. Through disrupting fibrotic epithelial-mesenchymal transition and TGF-β signaling transduction pathways, PE improves TIF and thereby facilitates renal excretion of PCS and IS in AAN. In light of multi-faced toxicity of AAs, PE may be capable of developing a new potential drug to treat CKD patients exposed to AAs.

Topics: Animals; Aristolochic Acids; Cresols; Disease Models, Animal; Epithelial-Mesenchymal Transition; Extracellular Signal-Regulated MAP Kinases; Fibrosis; Indican; JNK Mitogen-Activated Protein Kinases; Kidney Tubules; Mice, Inbred C57BL; Propolis; Renal Insufficiency, Chronic; Signal Transduction; Smad2 Protein; Smad3 Protein; Sulfuric Acid Esters; Transforming Growth Factor beta; Uremia

The present study was designed to evaluate the effect of sodium copper chlorophyllin (SCC) in adenine-induced chronic kidney disease (CKD). CKD was induced in male Wistar rats by feeding 0.3% w/w adenine diet for 28 days. After induction, animals were treated with sodium copper chlorophyllin at dose 2.7, 5.4, and 10.8 mg/kg for the next 28 days. The biochemical and urines parameters like creatinine, blood urea nitrogen (BUN), albumin, total protein creatinine clearance, urea clearance, and glomerular filtration rate were assessed on days 0, 14, and 28. Plasma TGF-β1, COX-2, and IL-6 levels were assessed. Various oxidative stress parameters and TGF-β1 expression were determined in the kidney. Histopathology of the kidney was studied with different stains. Sodium copper chlorophyllin-treated animals showed a significant reduction in urine output and relative kidney weight. The treatment with sodium copper chlorophyllin significantly improved kidney function by normalizing biochemical and urine parameters. Treatment with SCC significantly reduced circulatory inflammatory mediators-TGF-β1, COX-2, and IL-6. Additionally, the treatment also significantly reduced oxidative stress and TGF-β1 expression in kidney tissues. Histopathology studies showed inhibition in the kidney damage due to the treatment of SCC. The sodium copper chlorophyllin treatment attenuated adenine-induced chronic kidney disease in rats.

Topics: Adenine; Animals; Antimutagenic Agents; Chlorophyllides; Cytokines; Dose-Response Relationship, Drug; Inflammation Mediators; Male; Rats; Rats, Wistar; Renal Insufficiency, Chronic; Transforming Growth Factor beta

BACKGROUND Cell cycle arrest and autophagy have been demonstrated to be involved in various transforming growth factor (TGF)-ß-mediated phenotype alterations of tubular epithelial cells (TECs) and tubulointerstitial fibrosis. But the relationship between cell cycle arrest and the autophagy induced by TGF-ß has not been explored well. MATERIAL AND METHODS The effects of autophagy inhibition on TGF-ß-induced cell cycle arrest in TECs were explored in vitro. Human kidney-2 (HK-2) cells were stimulated by TGF-ß with or without a combined treatment of autophagy inhibitor chloroquine (CQ) or bafilomycin A1 (Baf). RESULTS Autophagy inhibition by CQ or Baf promotes the suppression of growth in TGF-ß-treated HK-2 cells, as detected by the Cell Counting Kit-8 (CCK-8) method. In addition, CQ or Baf stimulation enhances G1 arrest in TGF-ß treated HK-2 cells, as investigated using propidium iodide (PI) staining and flow cytometry, which was further confirmed by a decrease in the expression of phosphorylated retinoblastoma protein (p-RB) and cyclin-dependent kinase 4 (CDK4). The upregulation of p21 induced by CQ or Baf may mediate an enhanced G1 arrest in TGF-ß treated HK-2 cells. Western blot analysis showed that TGF-ß-induced expression of extracellular matrix fibronectin was notably upregulated in the presence of autophagy inhibitors. CONCLUSIONS Inhibition of autophagy sensitizes the TECs to G1 arrest and proliferation suppression induced by TGF-ß that contributes to the induction of tubulointerstitial fibrosis.

Topics: Autophagy; Cell Line; Cell Proliferation; Chloroquine; Cyclin-Dependent Kinase 4; Cyclin-Dependent Kinase Inhibitor p21; Enzyme Inhibitors; Epithelial Cells; Fibronectins; Fibrosis; G1 Phase Cell Cycle Checkpoints; Humans; In Vitro Techniques; Kidney Tubules; Macrolides; Renal Insufficiency, Chronic; Retinoblastoma Protein; Transforming Growth Factor beta

The growth arrest and DNA damage-inducible beta (Gadd45β) protein have been associated with various cellular functions, but its role in progressive renal disease is currently unknown. Here, we examined the effect of Gadd45β deletion on cell proliferation and apoptosis, inflammation, and renal fibrosis in an early chronic kidney disease (CKD) mouse model following unilateral ureteral obstruction (UUO). Wild-type (WT) and Gadd45β-knockout (KO) mice underwent either a sham operation or UUO and the kidneys were sampled eight days later. A histological assay revealed that ablation of Gadd45β ameliorated UUO-induced renal injury. Cell proliferation was higher in Gadd45β KO mouse kidneys, but apoptosis was similar in both genotypes after UUO. Expression of pro-inflammatory cytokines after UUO was down-regulated in the kidneys from Gadd45β KO mice, whereas UUO-mediated immune cell infiltration remained unchanged. The expression of pro-inflammatory cytokines in response to LPS stimulation decreased in bone marrow-derived macrophages from Gadd45β KO mice compared with that in WT mice. Importantly, UUO-induced renal fibrosis was ameliorated in Gadd45β KO mice unlike in WT mice. Gadd45β was involved in TGF-β signalling pathway regulation in kidney fibroblasts. Our findings demonstrate that Gadd45β plays a crucial role in renal injury and may be a therapeutic target for the treatment of CKD.

Topics: Animals; Antigens, Differentiation; Apoptosis; Biomarkers; Biopsy; Cell Line; Cell Proliferation; Cytokines; Disease Models, Animal; Disease Susceptibility; Fibrosis; Gene Deletion; Immunohistochemistry; Inflammation; Inflammation Mediators; Kidney Diseases; Male; Mice; Mice, Knockout; Renal Insufficiency, Chronic; Transforming Growth Factor beta; Ureteral Obstruction

The purpose of the present study was to investigate the expressions of hsa-let-7c-5p and TGF-

Topics: Adult; Female; Humans; Kidney; Male; MicroRNAs; Middle Aged; Renal Insufficiency, Chronic; Signal Transduction; Transforming Growth Factor beta

We previously used global Hipk2-null mice in various models of kidney disease to demonstrate the central role of homeodomain-interacting protein kinase 2 (HIPK2) in renal fibrosis development. However, renal tubular epithelial cell-specific (RTEC-specific) HIPK2 function in renal fibrogenesis has yet to be determined. Here, we show that modulation of tubular HIPK2 expression and activity affects renal fibrosis development in vivo. The loss of HIPK2 expression in RTECs resulted in a marked diminution of renal fibrosis in unilateral ureteral obstruction (UUO) mouse models and HIV-associated nephropathy (HIVAN) mouse models, which was associated with the reduction of Smad3 activation and downstream expression of profibrotic markers. Conversely, WT HIPK2 overexpression in RTECs accentuated the extent of renal fibrosis in the setting of UUO, HIVAN, and folic acid-induced nephropathy in mice. Notably, kinase-dead HIPK2 mutant overexpression or administration of BT173, an allosteric inhibitor of HIPK2-Smad3 interaction, markedly attenuated the renal fibrosis in these mouse models of kidney disease, indicating that HIPK2 requires both the kinase activity and its interaction with Smad3 to promote TGF-β-mediated renal fibrosis. Together, these results establish an important RTEC-specific role of HIPK2 in kidney fibrosis and further substantiate the inhibition of HIPK2 as a therapeutic approach against renal fibrosis.

Topics: AIDS-Associated Nephropathy; Animals; Fibrosis; Humans; Kidney Tubules; Loss of Function Mutation; Mice; Mice, Inbred C57BL; Protein Serine-Threonine Kinases; Renal Insufficiency, Chronic; Smad3 Protein; Transforming Growth Factor beta

This study aimed to understand the mechanistic role of N-methyl-D-aspartate receptor (NMDAR) in acute fibrogenesis using models of in vivo ureter obstruction and in vitro TGF-β administration.. The expression of NR1 was upregulated in obstructed kidneys, while NR1 knockdown significantly reduced both interstitial volume expansion and the changes in the expression of α-smooth muscle actin, S100A4, fibronectin, COL1A1, Snail, and E-cadherin in acute RF. TGF-β1 treatment increased the elongation phenotype of HK-2 cells and the expression of membrane-located NR1 and phosphorylated CaMKII and extracellular signal-regulated kinase (ERK). MK801 and KN93 reduced CaMKII and ERK phosphorylation levels, while MK801, but not KN93, reduced the membrane NR1 signal. The levels of phosphorylated CaMKII and ERK also increased in kidneys with obstruction but were decreased by NR1 knockdown. The 4-week administration of DXM preserved renal cortex volume in kidneys with moderate ischemic-reperfusion injury.. NMDAR participates in both acute and chronic renal fibrogenesis potentially via CaMKII-induced ERK activation.

Topics: Animals; Benzylamines; Calcium-Calmodulin-Dependent Protein Kinase Type 2; Dextromethorphan; Dizocilpine Maleate; Epithelial-Mesenchymal Transition; Excitatory Amino Acid Antagonists; Fibrosis; Gene Knockdown Techniques; Humans; In Vitro Techniques; Kidney; Kidney Tubules, Proximal; Mice; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Protein Kinase Inhibitors; Receptors, N-Methyl-D-Aspartate; Renal Insufficiency, Chronic; Reperfusion Injury; Sulfonamides; Transforming Growth Factor beta; Ureteral Obstruction

Renal fibrosis is a common pathological hallmark of chronic kidney disease (CKD). Renal sympathetic nerve activity is elevated in patients and experimental animals with CKD and contributes to renal interstitial fibrosis in obstructive nephropathy. However, the mechanisms underlying sympathetic overactivation in renal fibrosis remain unknown. Norepinephrine (NE), the main sympathetic neurotransmitter, was found to promote TGF-β1-induced epithelial-mesenchymal transition (EMT) and fibrotic gene expression in the human renal proximal epithelial cell line HK-2. Using both genetic and pharmacological approaches, we identified that NE binds Gαq-coupled α1-adrenoceptor (α1-AR) to enhance EMT of HK-2 cells by activating p38/Smad3 signaling. Inhibition of p38 diminished the NE-exaggerated EMT process and increased the fibrotic gene expression in TGF-β1-treated HK-2 cells. Moreover, the pharmacological blockade of α1-AR reduced the kidney injury and renal fibrosis in a unilateral ureteral obstruction mouse model by suppressing EMT in the kidneys. Thus, sympathetic overactivation facilitates EMT of renal epithelial cells and fibrosis via the α1-AR/p38/Smad3 signaling pathway, and α1-AR inhibition may be a promising approach toward treating renal fibrosis.

Topics: Adrenergic alpha-1 Receptor Antagonists; Adrenergic alpha-Agonists; Animals; Cell Line; Epithelial Cells; Epithelial-Mesenchymal Transition; Fibrosis; Humans; Male; Mice; Mice, Inbred C57BL; Norepinephrine; p38 Mitogen-Activated Protein Kinases; Receptors, Adrenergic, alpha-1; Renal Insufficiency, Chronic; Smad3 Protein; Tamsulosin; Transforming Growth Factor beta; Urethral Obstruction

In end-stage renal disease (ESRD) patients receiving dialysis, anemia is common and related to a higher mortality rate. Erythropoietin (EPO) resistance and iron refractory anemia require red blood cell transfusions. Myelodysplastic syndrome (MDS) is a disease with hematopoietic dysplasia. There are limited reports regarding ESRD patients with MDS. We aim to assess whether, for ESRD patients, undergoing dialysis is a predictive factor of MDS by analyzing data from the Taiwan National Health Insurance Research Database. We enrolled 74,712 patients with chronic renal failure (ESRD) who underwent dialysis and matched 74,712 control patients. In our study, we noticed that compared with the non-ESRD controls, in ESRD patients, undergoing dialysis (subdistribution hazard ratio [sHR] = 1.60, 1.16-2.19) and age (sHR = 1.03, 1.02-1.04) had positive predictive value for MDS occurrence. Moreover, more units of red blood cell transfusion (higher than 4 units per month) was also associated with a higher incidence of MDS. The MDS cumulative incidence increased with the duration of dialysis in ESRD patients. These effects may be related to exposure to certain cytokines, including interleukin-1, tumor necrosis factor-α, and tumor growth factor-β. In conclusion, we report the novel finding that ESRD patients undergoing dialysis have an increased risk of MDS.

Topics: Adult; Aged; Anemia; Erythrocyte Transfusion; Erythropoietin; Female; Humans; Interleukin-1; Iron; Kidney Failure, Chronic; Male; Middle Aged; Myelodysplastic Syndromes; Proportional Hazards Models; Renal Dialysis; Renal Insufficiency, Chronic; Transforming Growth Factor beta; Tumor Necrosis Factor-alpha

Renal fibrosis is a characteristic of diabetic nephropathy, which is a serious complication of diabetes. It has been reported that (-)-epigallocatechin gallate (EGCG) attenuates renal fibrosis. However, the molecular mechanism of regulation by EGCG in this process remains unclear. Previous studies showed that abnormal activation of Notch signaling contributes to the development of renal fibrosis. Previous studies have demonstrated that EGCG attenuates Notch1 expression. In this study, we found that the levels of fibronectin and Notch1 expression were decreased in human embryonic kidney cells after treatment with EGCG. We also observed that the type II transforming growth factor beta receptor (TGFβRII) and Smad3 pathway were inhibited in kidney cells by treatment with EGCG. In the diabetic kidney, we found that the activation of Notch signaling was attenuated by administration of EGCG. Moreover, TGFβRII and Smad3 phosphorylation could be inhibited by treatment with EGCG in the kidney. These results indicated that EGCG may improve renal fibrosis by targeting Notch via inhibition of the TGFβ/Smad3 pathway in diabetic mice. Our findings provide insight into the therapeutic strategy for diabetes-induced renal fibrosis, and suggest EGCG to be a novel potential medicine for the treatment of chronic kidney disease in patients with diabetes.

Topics: Animals; Antioxidants; Catechin; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Female; Injections, Intraperitoneal; Mice; Mice, Inbred ICR; Random Allocation; Renal Insufficiency, Chronic; Signal Transduction; Smad3 Protein; Streptozocin; Transforming Growth Factor beta

Topics: Animals; Extracellular Matrix; Fibrosis; Humans; Kidney; Renal Insufficiency, Chronic; Transforming Growth Factor beta; Vascular Endothelial Growth Factor A

Peritoneal fibrosis (PF) represents a long-term complication of peritoneal dialysis (PD), affecting peritoneal membrane (PM) integrity and function. Understanding the mechanisms underlying PF development in an uremic environment aiming alternative therapeutic strategies for treating this process is of great interest. The aim of this study was to analyze the effects of tamoxifen (TAM) and recombinant BMP7 (rBMP7) in an experimental model of PF developed in uremic rats.. To mimic the clinical situation of patients on long-term PD, a combo model, characterized by the combination of PF and CKD with severe uremia, was developed in Wistar rats. PF was induced by intraperitoneal (IP) injections of chlorhexidine gluconate (CG), and CKD was induced by an adenine-rich diet. Uremia was confirmed by severe hypertension, increased blood urea nitrogen (BUN> 120 mg/dL) and serum creatinine levels (> 2 mg/dL). Uremic rats with PF were treated with TAM (10 mg/Kg by gavage) or BMP7 (30 μg/Kg, IP). Animals were followed up for 30 days.. CG administration in uremic rats induced a striking increase in PM thickness, neoangiogenesis, demonstrated by increased capillary density, and failure of ultrafiltration capacity. These morphological and functional changes were blocked by TAM or rBMP7 treatment. In parallel, TAM and rBMP7 significantly ameliorated the PM fibrotic response by reducing α-SMA, extracellular matrix proteins and TGF-ß expression. TAM or rBMP7 administration significantly inhibited peritoneal Smad3 expression in uremic rats with PF, prevented Smad3 phosphorylation, and induced a remarkable up-regulation of Smad7, an intracellular inhibitor of TGFβ/Smad signaling, contributing to a negative modulation of profibrotic genes. Both treatments were also effective in reducing local inflammation, possibly by upregulating IκB-α expression in the PM of uremic rats with PF. In vitro experiments using primary peritoneal fibroblasts activated by TGF-ß confirmed the capacity of TAM or rBMP7 in blocking inflammatory mediators, such as IL-1ß expression.. In conclusion, these findings indicate important roles of TGF-ß/Smad signaling in PF aggravated by uremia, providing data regarding potential therapeutic approaches with TAM or rBMP7 to block this process.

Topics: Animals; Bone Morphogenetic Protein 7; Cells, Cultured; Disease Models, Animal; Inflammation; Male; Peritoneal Fibrosis; Peritoneum; Rats; Rats, Wistar; Recombinant Proteins; Renal Insufficiency, Chronic; Smad7 Protein; Tamoxifen; Transforming Growth Factor beta; Uremia

Reactivation of Notch signaling in kidneys of animal models and patients with chronic kidney disease (CKD) has been shown to contribute to epithelial injury and fibrosis development. Here, we investigated the mechanisms of Notch-induced injury in renal epithelial cells. We performed genome-wide transcriptome analysis to identify Notch target genes using an in vitro system of cultured tubular epithelial cells expressing the intracellular domain of Notch1. One of the top downregulated genes was Disabled-2 ( Dab2). With the use of Drosophila nephrocytes as a model system, we found that Dab (the Drosophila homolog of Dab2) knockdown resulted in a significant filtration defect, indicating that loss of Dab2 plays a functional role in kidney disease development. We showed that Dab2 expression in cultured tubular epithelial cells is involved in endocytic regulation and that it also protects cells from TGF-β-induced epithelial-to-mesenchymal transition. In vivo correlation studies indicated its additional role in renal ischemia-induced injury. Together, these data suggest that Dab2 plays a versatile role in the kidney and may impact on acute and CKDs.-Schütte-Nütgen, K., Edeling, M., Mendl, G., Krahn, M. P., Edemir, B., Weide, T., Kremerskothen, J., Michgehl, U., Pavenstädt, H. Getting a Notch closer to renal dysfunction: activated Notch suppresses expression of the adaptor protein Disabled-2 in tubular epithelial cells.

Topics: Adaptor Proteins, Vesicular Transport; Animals; Cell Differentiation; Cell Line; Down-Regulation; Endocytosis; Epithelial Cells; Epithelial-Mesenchymal Transition; Kidney; Kidney Tubules; Male; Rats; Rats, Sprague-Dawley; Receptors, Notch; Renal Insufficiency, Chronic; Signal Transduction; Transforming Growth Factor beta

Peritoneal dialysis (PD) is limited by chronic fibrotic remodeling of the peritoneal wall, a transforming growth factor-β (TGF-β)-mediated process. The fractalkine (CX3CL1) receptor CX3CR1 is expressed on macrophages and monocytes, where it is a marker of TGFβ expression. Detection of its ligand CX3CL1 on the peritoneal mesothelium led us to hypothesize a pathophysiologic role of CX3CL1-CX3CR1 interaction in peritoneal fibrosis. We found that CX3CL1 was expressed on peritoneal mesothelial cells from PD patients and in a murine PD model. CX3CR1, mostly expressed on macrophages in the peritoneal wall, promoted fibrosis induced by chronic dialysate exposure in the mouse model. Our data suggest a positive feedback loop whereby direct interaction with CX3CR1-expressing macrophages promotes mesothelial expression of CX3CL1 and TGFβ expression. In turn, TGFβ upregulates CX3CR1 in murine and human monocytic cells. Upstream, macrophage cytokines including interleukin-1β (IL-1β) promote mesothelial CX3CR1 and TGFβ expression, providing a starting point for CX3CL1-CX3CR1 interaction. IL-1β expression was enhanced by exposure to dialysate both in vitro and in the mouse models. Our data suggest that macrophage-mesothelial cell crosstalk through CX3CR1-CX3CL1 interaction enhances mesothelial TGFβ production, promoting peritoneal fibrosis in response to dialysate exposure. This interaction could be a novel therapeutic target in PD-associated chronic peritoneal fibrosis.

Topics: Aged; Animals; Cell Communication; Cell Line; Cells, Cultured; Chemokine CX3CL1; Coculture Techniques; CX3C Chemokine Receptor 1; Dialysis Solutions; Disease Models, Animal; Epithelial Cells; Female; Humans; Interleukin-1beta; Leukocytes, Mononuclear; Macrophages, Peritoneal; Male; Mice; Middle Aged; Peritoneal Dialysis; Peritoneal Fibrosis; Peritoneum; Primary Cell Culture; Renal Insufficiency, Chronic; Transforming Growth Factor beta; Up-Regulation

The present study investigated the role of the c‑Jun N‑terminal kinase (JNK)/transforming growth factor‑β (TGF‑β)/Smad3 pathway in endoplasmic reticulum stress (ERS)‑mediated renal interstitial fibrosis, which would be beneficial for chronic kidney disease (CKD) therapy. In human renal biopsy tissue, the expression levels of glucose‑regulated protein 78 (GRP78) and phosphorylated (p)‑JNK were examined by immunohistochemical analysis. In renal tubular HK‑2 cells, tunicamycin (TM) was used to induce ERS, and the cells were then treated with the chemical ERS inhibitor 4‑phenylbutyrate (4‑PBA) or the chemical JNK pathway inhibitor SP600125, respectively. Western blotting was then performed in the cells to determine the expression levels of GRP78 and p‑JNK proteins, as well as TGF‑β/Smad3 pathway‑associated proteins, including TGF‑β1, p‑Smad3, connective tissue growth factor and α‑smooth muscle actin. The results revealed that GRP78 and p‑JNK were evidently expressed in the renal tissues of patients with CKD, and these expression levels were significantly higher in renal tissues with severe interstitial fibrosis compared with glomerular minor lesion tissues (P<0.01 and P<0.05, respectively). Furthermore, ERS and JNK pathway inhibition decreased the expression levels of TGF‑β/Smad3 pathway signals in cells incubated with TM. ERS pathway inhibition also attenuated the expression levels of p‑JNK in HK‑2 cells. In conclusion, ERS was observed to serve an important role in the pathogenesis of CKD and may induce renal interstitial fibrosis via the JNK/TGF‑β/Smad3 pathway.

Topics: Adult; Endoplasmic Reticulum Chaperone BiP; Endoplasmic Reticulum Stress; Female; Fibrosis; Humans; JNK Mitogen-Activated Protein Kinases; Kidney; Male; Middle Aged; Renal Insufficiency, Chronic; Signal Transduction; Smad3 Protein; Transforming Growth Factor beta

Chronic kidney disease (CKD) involves interstitial fibrosis as an underlying pathological process associated with compromised renal function irrespective of etiological cause of the injury. The transforming growth factor-β (TGF-β) plays a pivotal role in progression of renal fibrosis. TGF-β transduces its downstream signalling by phosphorylation of smad2/3 and also regulates epithelial-mesenchymal-transition (EMT), a program centrally involved in activation of fibroblasts. Renal fibrosis was induced in Swiss albino mice by unilateral ureteral obstruction of animals. Kidney tissues were evaluated for fibrotic protein expression by western blot and immunohistochemistry. The administration of nimbolide (NB) to UUO animals reduced the oxidative stress, expression of ECM proteins, TGF-β, p-smad and EMT program. Further, NB administration also improved histoarchitecture of obstructed kidney and reduced the collagen deposition in kidney. Our results provided compelling evidence to support antifibrotic activity of NB by reduction in oxidative stress, TGF-β, and EMT program in fibrotic kidney. The administration of NB in animals blunted the UUO-induced renal injury, inflammation and reduced fibrogenesis in obstructed kidney.

Topics: Animals; Epithelial-Mesenchymal Transition; Fibrosis; Kidney; Limonins; Male; Mice; Oxidative Stress; Renal Insufficiency, Chronic; Signal Transduction; Smad2 Protein; Smad3 Protein; Snail Family Transcription Factors; Transforming Growth Factor beta; Ureteral Obstruction

The antiviral drug Telbivudine (LdT) has an extrahepatic pharmaceutical effect that improves renal inflammation and tubulointerstitial fibrosis. However, the exact mechanism of action requires further investigation. Toll-like receptor 4 (TLR4) is involved in several physiological processes, including inflammation, fibrosis, innate immunity, and hepatitis B virus-associated glomerulonephritis. The epithelial-to-mesenchymal transition (EMT) is the characteristic pathological change in tubulointerstitial fibrosis. In this study, we used transforming growth factor-β (TGF-β) to stimulate human proximal tubular epithelial (HK-2) cells to investigate the effects of LdT in EMT. In addition, we treated HK-2 cells with a TLR4 agonist, lipopolysaccharide, to determine the effect of LdT on TLR4. The results indicated that LdT inhibited the expression of TLR4 and its downstream proteins. It also decreased the release of inflammatory factors, downregulated the TGF-β/Smad signaling pathway, and reversed the EMT changes seen in HK-2 cells. In conclusion, LdT antagonized TLR4 to inhibit EMT in proximal tubular epithelial cells.

Topics: Antiviral Agents; Cell Line; Epithelial Cells; Epithelial-Mesenchymal Transition; Fibrosis; Humans; Immunity, Innate; Kidney Tubules, Proximal; Lipopolysaccharides; Renal Insufficiency, Chronic; Signal Transduction; Smad Proteins; Telbivudine; Toll-Like Receptor 4; Transforming Growth Factor beta

Acupuncture is one of the most useful tools in complimentary medicine, and has demonstrated potential value for treating chronic renal failure (CRF). However, the underlying mechanisms for its therapeutic effect remain unknown. In the present study, the effects of acupuncture on renal interstitial fibrosis (RIF) were explored in a rabbit model of CRF. Rabbits were assigned to the following five groups: sham, model, losartan potassium (Posi), acupuncture (Acup) and acupuncture+inhibitor (Acup+Inhib) groups. The CRF rabbits were administered a drug or/and acupuncture on Shenshu, Mingmen and Pishu. The body weights, urine protein, serum creatinine (SCr) and blood urea nitrogen (BUN) levels of the rabbits were measured. Transforming growth factor β (TGF‑β), integrin‑linked kinase (ILK) and Smad3 expression were detected by qRT‑PCR. Tumor necrosis factor‑α (TNF‑α) and endothelial nitric oxide synthase (eNOS) expression were analyzed by western blot methods. The concentrations of TGF‑β, IL‑8, TNF‑α and IL‑1β in blood serum were detected using ELISA kits. In addition, pathological characteristics of the rabbit tissues were evaluated by H&E and Masson's trichrome staining methods, and TGF‑β expression was detected by immunohistochemistry (IHC) assays. Results showing decreased body weights and increased urine protein, SCr and BUN levels confirmed that the CRF model had been successfully constructed. It was also found that acupuncture significantly reduced the levels of TNF‑α, Smad3, ILK and TGF‑β expression, dramatically decreased the concentrations of TGF‑β, IL‑8, TNF‑α and IL‑1β in blood serum, and significantly increased eNOS expression in the CRF model rabbits by affecting the TGF‑β/Smad signaling pathway. In addition, it was demonstrated that acupuncture could relieve RIF by affecting the TGF‑β/Smad pathway. These observations indicate that acupuncture may be useful for treating CRF, and suggest the TGF‑β/Smad pathway as a target for CRF therapy.

Topics: Acupuncture Therapy; Animals; Fibrosis; Kidney; Male; Rabbits; Renal Insufficiency, Chronic; Signal Transduction; Smad Proteins; Transforming Growth Factor beta

Cellular senescence is associated with renal disease progression, and accelerated tubular cell senescence promotes the pathogenesis of renal fibrosis. However, the underlying mechanism is unknown. We assessed the potential role of Wnt9a in tubular cell senescence and renal fibrosis. Compared with tubular cells of normal subjects, tubular cells of humans with a variety of nephropathies and those of several mouse models of CKD expressed high levels of Wnt9a that colocalized with the senescence-related protein p16

Topics: Animals; Cell Line; Cellular Senescence; Cyclin-Dependent Kinase Inhibitor p16; Disease Models, Animal; Epithelial Cells; Fibroblasts; Fibrosis; Gene Expression Regulation; Genes, p16; Humans; Kidney; Kidney Tubules; Male; Mice; Mice, Inbred C57BL; Rats; Recombinant Proteins; Renal Insufficiency, Chronic; Reperfusion Injury; RNA Interference; Transforming Growth Factor beta; Tumor Suppressor Proteins; Wnt Proteins; Wnt Signaling Pathway

Topics: Animals; Calcium Oxalate; Crystallization; Diet; Disease Models, Animal; Fibrosis; Glomerular Filtration Rate; Humans; Immunoglobulin G; Kidney; Male; Mice; Mice, Inbred C57BL; Nephrocalcinosis; Oxalates; Renal Insufficiency, Chronic; Transforming Growth Factor beta

Emerging evidence suggests that chronic metabolic acidosis (CMA) may have significant implications in terms of worsening renal disease in CKD patients, but the effect of CMA on renal function and structure has not been fully elucidated.. We studied the acute and chronic consequences of an acid load (AL) on glomerular filtration rate (GFR) and renal histology in C57BL/6 mice. FITC-inulin clearance was performed at several time points; markers of renal fibrosis were studied at mRNA and protein levels; finally, kidney expression of candidate molecules triggering changes in renal function was studied.. Glomerular hyperfiltration occurred within 1-3 days from AL; after 1 week, the GFR returned to baseline and then declined progressively within 15-21 days. The GFR decline was accompanied by the onset of renal fibrosis, as shown by Masson trichrome staining. Markers of renal fibrosis, namely α-smooth muscle actin and collagen-1, increased after 1 day of acid loading in both mRNA and protein levels and remained higher than baseline for up to 21 days. Well-known mediators of renal fibrosis, including transforming growth factor (TGF)-β and the intrarenal renin-angiotensin system (RAS) axis, were increased even before the decline of the GFR.. Acid load caused hyperfiltration acutely and a progressive decline of the GFR chronically; the evidence of renal fibrosis indicates that structural and not only functional renal changes occurred. The concomitant upregulation of TGF-β and intrarenal RAS axis indicates that those factors may be potentially involved in the progression of kidney disease in this setting.

Topics: Acidosis; Actins; Ammonium Chloride; Angiotensinogen; Animals; Chronic Disease; Collagen Type I; Disease Progression; Fibrosis; Gene Expression; Glomerular Filtration Rate; Hydrochloric Acid; Kidney; Male; Mice, Inbred C57BL; Renal Insufficiency, Chronic; Renin; Renin-Angiotensin System; RNA, Messenger; Transforming Growth Factor beta

Chronic kidney disease (CKD), a condition in which the kidneys are unable to clear waste products, affects 700 million people globally. Genome-wide association studies (GWASs) have identified sequence variants for CKD; however, the biological basis of these GWAS results remains poorly understood. To address this issue, we created an expression quantitative trait loci (eQTL) atlas for the glomerular and tubular compartments of the human kidney. Through integrating the CKD GWAS with eQTL, single-cell RNA sequencing and regulatory region maps, we identified novel genes for CKD. Putative causal genes were enriched for proximal tubule expression and endolysosomal function, where DAB2, an adaptor protein in the TGF-β pathway, formed a central node. Functional experiments confirmed that reducing Dab2 expression in renal tubules protected mice from CKD. In conclusion, compartment-specific eQTL analysis is an important avenue for the identification of novel genes and cellular pathways involved in CKD development and thus potential new opportunities for its treatment.

Topics: Adaptor Proteins, Signal Transducing; Animals; Apoptosis Regulatory Proteins; Cell Compartmentation; Disease Models, Animal; Gene Expression Regulation; Genetic Predisposition to Disease; Genome-Wide Association Study; Humans; Kidney; Kidney Glomerulus; Kidney Tubules, Proximal; Mice; Polymorphism, Single Nucleotide; Quantitative Trait Loci; Renal Insufficiency, Chronic; Signal Transduction; Transforming Growth Factor beta; Tumor Suppressor Proteins

Cardiovascular disease constitutes the leading cause of mortality in patients with chronic kidney disease (CKD) and end-stage renal disease. Despite increasing recognition of a close interplay between kidney dysfunction and cardiovascular disease, termed cardiorenal syndrome (CRS), the underlying mechanisms of CRS remain poorly understood. Here we report the development of pathological cardiac hypertrophy and fibrosis in early stage non-uremic CKD. Moderate kidney failure was induced three weeks after unilateral urinary obstruction (UUO) in mice. We observed pathological cardiac hypertrophy and increased fibrosis in UUO-induced CKD (UUO/CKD) animals. Further analysis indicated that this cardiac fibrosis was associated with increased expression of transforming growth factor β (TGF-β) along with significant upregulation of Smad 2/3 signaling in the heart. Moreover early treatment of UUO/CKD animals with an angiotensin-converting-enzyme inhibitor (ACE I), Enalapril, significantly attenuated cardiac fibrosis. Enalapril antagonized activation of the TGF-β signaling pathway in the UUO/CKD heart. In summary our study demonstrates the presence of pathological cardiac hypertrophy and fibrosis in mice early in UUO-induced CKD, in association with early activation of the TGF-β/Smad signaling pathway. We also demonstrate the beneficial effect of ACE I in alleviating this early fibrogenic process in the heart in UUO/CKD animals.

Topics: Angiotensin-Converting Enzyme Inhibitors; Animals; Blood Pressure; Cardiomegaly; Enalapril; Fibrosis; Heart Ventricles; Hypertension; Male; Mice, Inbred C57BL; Organ Size; Renal Insufficiency, Chronic; Signal Transduction; Transforming Growth Factor beta; Up-Regulation; Ureteral Obstruction; Ventricular Remodeling

TGF-β is induced in the vasculature with aging suggesting that high plasma TGF-β levels may be a risk factor for chronic kidney disease (CKD) in older adults.. Plasma TGF-β levels were significantly and independently associated with lower eGFR in cross-sectional analysis. Doubling of TGF-β was significantly associated with lower eGFR (β estimate after adjusting for CV risk factors = -1.18, 95% CI -2.03, -0.32). We observed no association with albuminuria. There was no association between baseline TGF-β and change in eGFR, but each doubling of TGF-β at baseline was associated with increased risk of a composite outcome of CV events and mortality, adjusted HR 1.10 (95% C.I. 1.02- 1.20, p = 0.006).. In this large cohort of community-dwelling older individuals, high plasma TGF-β levels are modestly, but independently associated with lower eGFR but not with albuminuria in cross-sectional analysis. In addition, TGF-β levels are associated with increased risk of CV events and mortality. Further research is needed to determine the direction of association between plasma TGF-β and the risk of CKD and CKD-associated morbidities in older adults.

Topics: Aged; Aged, 80 and over; Albuminuria; Cohort Studies; Creatinine; Cross-Sectional Studies; Female; Glomerular Filtration Rate; Humans; Independent Living; Male; Prevalence; Proportional Hazards Models; Prospective Studies; Renal Insufficiency, Chronic; Transforming Growth Factor beta; United States

Chronic kidney disease (CKD) and arterial stiffness are associated with increased cardiovascular morbidity and mortality. Inflammation is proposed to have a role in the development of arterial stiffness, and CKD is recognized as a proinflammatory state. Arterial stiffness is increased in CKD, and cross-sectional data has suggested a link between increased inflammatory markers in CKD and higher measures of arterial stiffness. However, no large scale investigations have examined the impact of inflammation on the progression of arterial stiffness in CKD.. We performed baseline assessments of 5 inflammatory markers in 3,939 participants from the chronic renal insufficiency cohort (CRIC), along with serial measurements of arterial stiffness at 0, 2, and 4 years of follow-up.. A total of 2,933 participants completed each of the follow-up stiffness measures. In cross-sectional analysis at enrollment, significant associations with at least 2 measures of stiffness were observed for fibrinogen, interleukin-6, high-sensitivity C-reactive protein, proteinuria, and composite inflammation score after adjustment for confounders. In longitudinal analyses, there were few meaningful correlations between baseline levels of inflammation and changes in metrics of arterial stiffness over time.. In a large cohort of CKD participants, we observed multiple significant correlations between initial markers of inflammation and metrics of arterial stiffness, but baseline inflammation did not predict changes in arterial stiffness over time. While well-described biologic mechanisms provide the basis for our understanding of the cross-sectional results, continued efforts to design longitudinal studies are necessary to fully elucidate the relationship between chronic inflammation and arterial stiffening.

Topics: Adult; Aged; Blood Pressure; C-Reactive Protein; Cohort Studies; Enzyme-Linked Immunosorbent Assay; Female; Fibrinogen; Follow-Up Studies; Humans; Inflammation; Interleukin 1 Receptor Antagonist Protein; Interleukin-1beta; Interleukin-6; Linear Models; Male; Middle Aged; Proteinuria; Pulse Wave Analysis; Renal Insufficiency, Chronic; Transforming Growth Factor beta; Tumor Necrosis Factor-alpha; Vascular Stiffness

Fibrogenesis involves the activation of renal fibroblasts upon kidney injury. However, the mechanisms underlying renal fibroblast activation are poorly characterized. c-Myc is a predominant oncogene encoding a pleiotropic transcription factor that participates in the regulation of various genes, including genes vital for regulating the cell cycle, cell proliferation, and apoptosis. Here we tested whether renal fibrosis in unilateral ureteral obstruction and folic acid-induced renal fibrosis mouse models are associated with the overexpression of c-Myc. Transforming growth factor-β (TGF-β) has been identified as a key mediator of renal fibrosis, and it is secreted in an inactive form as a complex with latency-associated peptide and latent TGF-β-binding proteins. Five αv-containing integrins with different β -subunits can activate TGF-β, and consistent with this we found that c-Myc bound directly to the promoter of integrin αv in renal fibroblasts activating its transcription. This, in turn, induced activation of TGF-β signaling. Pharmacological blockade of c-Myc attenuated renal fibrosis in vivo in the ureteral obstruction and folic acid-treated mouse models and inhibited the proliferation and activation of renal fibroblasts in vitro. Thus, c-Myc overexpression stimulated proliferation and activation of renal fibroblasts by inducing integrin αv -mediated TGF-β signaling. Hence, targeting c-Myc may have clinical utility in the treatment of renal fibrosis.

Topics: Angiotensin II; Animals; Extracellular Matrix; Fibroblasts; Fibrosis; Folic Acid; Integrin alphaV; Kidney; Male; Mice; Mice, Inbred C57BL; Proto-Oncogene Proteins c-myc; Renal Insufficiency, Chronic; Signal Transduction; Thiazoles; Transforming Growth Factor beta; Up-Regulation; Ureteral Obstruction

Topics: Animals; Cells, Cultured; Diabetic Nephropathies; Humans; Male; Mice; Mice, Inbred C57BL; Naphthalenes; Nitric Oxide Synthase Type III; Phenylbutyrates; Podocytes; Rats; Rats, Sprague-Dawley; Receptors, Prostaglandin E, EP4 Subtype; Renal Insufficiency, Chronic; Transforming Growth Factor beta

High aldosterone level may contribute to pathogenesis of hypertension, vessels damage and cardiovascular system deterioration in chronic kidney disease patients. Besides its classical action via mineralocorticoid receptor, aldosterone is also involved in cell growth, inflammation, oxidative stress, endothelial dysfunction and exerts fibroproliferative effects. The aim of the study was to assess whether aldosterone antagonist treatment may influence serum level of inflammatory, fibrosis, thrombosis and mineral-bone metabolism markers in peritoneal dialysis (PD) patients and blood pressure, aortic stiffness, echocardiographic indices after 12 months of treatment.. Twenty-two patients on PD were assigned to spironolactone treatment in dose of 50 mg daily during 12 months. Fifteen PD patients were assigned to control group. Echocardiographic indices, PVW, SBP, DBP (mean values from ABPM) and biochemical parameters such as: aldosterone, osteopontin, IL-6, selectin-P, TGF-β, PTH, MMP-2 were performed at the beginning and after 12 months in spironolactone and control group.. There were no statistically significant differences in echocardiographic indices, PWV, BP (ABPM readings) and biochemical markers: MMP-2, serum aldosterone, TGF-β, IL-6, selectin-P, PTH level after 12 months of spironolactone treatment. There was statistically significant rise in osteopontin level after 12 months of spironolactone treatment. Episodes of life-threatening hyperkalemia were not reported.. Aldosterone antagonists use in PD patients seems to be safe. Longer duration or higher dosage of spironolactone seems to be more effective in improving cardiovascular system status in PD patients. Further studies are required to determine relationship between mineralocorticoid receptor blockade and mineral-bone disturbances in PD patients.

Topics: Adult; Aged; Aged, 80 and over; Aldosterone; Biomarkers; Blood Pressure; Cardiovascular Diseases; Chronic Kidney Disease-Mineral and Bone Disorder; Echocardiography; Female; Fibrosis; Humans; Inflammation; Interleukin-6; Male; Matrix Metalloproteinase 2; Middle Aged; Mineralocorticoid Receptor Antagonists; Osteopontin; P-Selectin; Parathyroid Hormone; Peritoneal Dialysis; Pulse Wave Analysis; Renal Insufficiency, Chronic; Spironolactone; Thrombosis; Transforming Growth Factor beta; Vascular Stiffness

Topics: beta Catenin; Fibrosis; Humans; Receptors, Transforming Growth Factor beta; Renal Insufficiency, Chronic; Transforming Growth Factor beta

Topics: Adult; Aged; Albumins; Animals; Cell Line; Disease Models, Animal; Female; Fibrosis; Gene Expression Profiling; Gene Regulatory Networks; Genetic Markers; Genetic Predisposition to Disease; Glomerular Filtration Rate; Humans; Kidney; Male; Mice, Inbred C57BL; Mice, Inbred CBA; Mice, Transgenic; MicroRNAs; Middle Aged; Oligonucleotide Array Sequence Analysis; Phenotype; Rats; Renal Insufficiency, Chronic; Transcriptome; Transforming Growth Factor beta; Transforming Growth Factor beta1

Although the effects of dipeptidyl peptidase 4 (DPP-4) inhibitors beyond their hypoglycemic action have been reported, whether these inhibitors have renoprotective effects in nondiabetic chronic kidney disease (CKD) is unclear. We examined the therapeutic effects of DPP-4 inhibition in mice with unilateral ureteral obstruction (UUO), a nondiabetic model of progressive renal fibrosis. After UUO surgery, mice were administered either the DPP-4 inhibitor alogliptin or a vehicle by oral gavage once a day for 10 days. Physiological parameters, degrees of renal fibrosis and inflammation, and molecules related to renal fibrosis and inflammation were then evaluated using sham-operated mice as controls. Positive area of α-smooth muscle actin was significantly smaller and expression of transforming growth factor β messenger RNA was significantly lower in the alogliptin-treated group than in the vehicle-treated group. Renal total collagen content was also significantly lower in the alogliptin-treated group than in the vehicle-treated group. These results suggest that alogliptin exerted renoprotective antifibrotic effects. The positive area of F4/80 was significantly smaller and expression of CD68 messenger RNA was significantly lower in the alogliptin-treated group than in the vehicle-treated group, suggesting an anti-inflammatory action by the DPP-4 inhibitor. Compared to the results for the vehicle-treated group, expression of markers for M1 macrophages tended to be lower in the alogliptin-treated group, and the relative expression of M2 macrophages tended to be higher. These data indicate the various protective effects of DPP-4 inhibition in nondiabetic mice with UUO. DPP-4 inhibitors may therefore be promising therapeutic choices even for nondiabetic CKD patients.

Topics: Actins; Animals; Antigens, CD; Antigens, Differentiation, Myelomonocytic; Blood Urea Nitrogen; Calcium-Binding Proteins; Creatinine; Dipeptidyl-Peptidase IV Inhibitors; Disease Models, Animal; Fibrosis; Kidney; Macrophages; Male; Mice; Mice, Inbred C57BL; Piperidines; Receptors, Cell Surface; Receptors, G-Protein-Coupled; Renal Insufficiency, Chronic; Transforming Growth Factor beta; Uracil; Ureteral Obstruction

Renal fibrosis is a common pathological feature of chronic kidney diseases (CKD) and its development and progression are significantly affected by epigenetic modifications such as aberrant miRNA and DNA methylation. Klotho is an anti-aging and anti-fibrotic protein and its early decline after renal injury is reportedly associated with aberrant DNA methylation. However, the key upstream pathological mediators and the molecular cascade leading to epigenetic Klotho suppression are not exclusively established. Here we investigate the epigenetic mechanism of Klotho deficiency and its functional relevance in renal fibrogenesis. Fibrotic kidneys induced by unilateral ureteral occlusion (UUO) displayed marked Klotho suppression and the promoter hypermethylation. These abnormalities were likely due to deregulated transforming growth factor-beta (TGFβ) since TGFβ alone caused the similar epigenetic aberrations in cultured renal cells and TGFβ blockade prevented the alterations in UUO kidney. Further investigation revealed that TGFβ enhanced DNA methyltransferase (DNMT) 1 and DNMT3a via inhibiting miR-152 and miR-30a in both renal cells and fibrotic kidneys. Accordingly the blockade of either TGFβ signaling or DNMT1/3a activities significantly recovered the Klotho loss and attenuated pro-fibrotic protein expression and renal fibrosis. Moreover, Klotho knockdown by RNA interferences abolished the anti-fibrotic effects of DNMT inhibition in both TGFβ-treated renal cell and UUO kidney, indicating that TGFβ-mediated miR-152/30a inhibitions, DNMT1/3a aberrations and subsequent Klotho loss constitute a critical regulatory loop that eliminates Klotho's anti-fibrotic activities and potentiates renal fibrogenesis. Thus, our study elaborates a novel epigenetic cascade of renal fibrogenesis and reveals the potential therapeutic targets for treating the renal fibrosis-associated kidney diseases.

Topics: Animals; DNA (Cytosine-5-)-Methyltransferase 1; DNA (Cytosine-5-)-Methyltransferases; DNA Methylation; DNA Methyltransferase 3A; Enzyme Inhibitors; Epigenesis, Genetic; Fibrosis; Glucuronidase; HEK293 Cells; Humans; Kidney; Klotho Proteins; Male; Mice; Mice, Inbred C57BL; MicroRNAs; Promoter Regions, Genetic; Renal Insufficiency, Chronic; Transforming Growth Factor beta

Chronic renal insufficiency inexorably progresses in patients, such as it does after partial renal ablation in rats. However, the progression of renal diseases can be delayed by angiotensin II blockers that stabilize renal function or increase GFR, even in advanced phases of the disease. Regression of glomerulosclerosis can be induced by angiotensin II antagonism, but the effect of these treatments on the entire vascular tree is unclear. Here, using microcomputed tomography and scanning electron microscopy, we compared the size and extension of kidney blood vessels in untreated Wistar rats with those in untreated and angiotensin II antagonist-treated Munich Wistar Frömter (MWF) rats that spontaneously develop kidney disease with age. The kidney vasculature underwent progressive rarefaction in untreated MWF rats, substantially affecting intermediate and small vessels. Microarray analysis showed increased Tgf-β and endothelin-1 gene expression with age. Notably, 10-week inhibition of the renin-angiotensin system regenerated kidney vasculature and normalized Tgf-β and endothelin-1 gene expression in aged MWF rats. These changes were associated with reduced apoptosis, increased endothelial cell proliferation, and restoration of Nrf2 expression, suggesting mechanisms by which angiotensin II antagonism mediates regeneration of capillary segments. These results have important implications in the clinical setting of chronic renal insufficiency.

Topics: Actins; Angiotensin Receptor Antagonists; Angiotensin-Converting Enzyme Inhibitors; Animals; Apoptosis; Capillaries; Cell Proliferation; Endothelial Cells; Endothelin-1; Gene Expression; Kidney Glomerulus; Microscopy, Electron, Scanning; Neovascularization, Physiologic; NF-E2-Related Factor 2; Rats; Rats, Wistar; Renal Insufficiency, Chronic; Renin-Angiotensin System; Transforming Growth Factor beta; X-Ray Microtomography

Progressive fibrosis in chronic kidney disease (CKD) is the well-recognized cause leading to the progressive loss of renal function. Emerging evidence indicated a pathogenic role of the NACHT, LRR and PYD domains-containing protein 3 (NLRP3) inflammasome in mediating kidney injury. However, the role of NLRP3 in the remnant kidney disease model is still undefined. The present study was undertaken to evaluate the function of NLRP3 in modulating renal fibrosis in a CKD model of 5/6 nephrectomy (5/6 Nx) and the potential involvement of mitochondrial dysfunction in the pathogenesis. Employing NLRP3(+/+) and NLRP3(-/-) mice with or without 5/6 Nx, we examined renal fibrotic response and mitochondrial function. Strikingly, tubulointerstitial fibrosis was remarkably attenuated in NLRP3(-/-) mice as evidenced by the blockade of extracellular matrix deposition. Meanwhile, renal tubular cells in NLRP3(-/-) mice maintained better mitochondrial morphology and higher mitochondrial DNA copy number, indicating an amelioration of mitochondrial abnormality. Moreover, NLRP3 deletion also blunted the severity of proteinuria and CKD-related hypertension. To further evaluate the direct role of NLRP3 in triggering fibrogenesis, mouse proximal tubular cells (PTCs) were subjected to transforming growth factor β1 (TGF-β1), and the cellular phenotypic changes were detected. As expected, TGF-β1-induced alterations of PTC phenotype were abolished by NLRP3 small interfering RNA, in line with a protection of mitochondrial function. Taken together, NLRP3 deletion protected against renal fibrosis in the 5/6 Nx disease model, possibly via inhibiting mitochondrial dysfunction.

Topics: Animals; Cells, Cultured; Hypertension; Mice; Mice, Inbred C57BL; Mitochondrial Diseases; Nephrectomy; Nephrosclerosis; NLR Family, Pyrin Domain-Containing 3 Protein; Proteinuria; Renal Insufficiency, Chronic; RNA, Small Interfering; Transforming Growth Factor beta

Development of renal dysfunction, including acute kidney injury (AKI) and chronic kidney disease (CKD), after liver transplantation (LT) remains a critical issue adversely affecting patient survival in both the short and long term. Previous reports have suggested that inflammatory and antiinflammatory cytokines and their functionally relevant gene polymorphisms may play critical roles in the development of AKI and CKD. However, the involvement of these cytokines and their gene polymorphisms in renal deterioration following LT remains unclear.. We examined 62 recipients who underwent LT at Nagoya University between 2004 and 2009 and who had survived for at least 1 year. The following gene polymorphisms in recipients were analyzed: tumor necrosis factor-A (TNFA) T-1031C, interleukin-2 (IL2) T-330G, IL10 C-819T, IL13 C-1111T, transforming growth factor-B (TGFB) T29C, and IL4 T-33C.. Thirteen patients (21 %) developed AKI within 4 weeks after LT. Of the investigated gene polymorphisms, the IL4 -33 T/T genotype was significantly associated with higher incidence of AKI compared with the other two genotypes [hazard ratio (HR) = 5.48, 95 % confidence interval (CI) 1.18-25.52, p = 0.03]. On the other hand, 16 patients (26 %) had developed CKD at median follow-up of 9.2 years after LT. We showed the lack of association between investigated gene polymorphisms in recipients and CKD development.. The IL4 -33 T/T genotype might be a risk factor for AKI in LT, and this might contribute to earlier withdrawal of immunosuppressive agents to minimize renal toxicity. In contrast, none of the investigated cytokine gene polymorphisms were associated with CKD.

Topics: Acute Kidney Injury; Adult; Female; Genetic Predisposition to Disease; Humans; Interleukin-10; Interleukin-13; Interleukin-2; Interleukin-4; Liver Transplantation; Male; Middle Aged; Polymorphism, Single Nucleotide; Proportional Hazards Models; Renal Insufficiency, Chronic; Retrospective Studies; Transforming Growth Factor beta; Tumor Necrosis Factor-alpha; Young Adult

Chronic kidney disease is associated with progressive renal fibrosis, where perivascular cells give rise to the majority of α-smooth muscle actin (α-SMA) positive myofibroblasts. Here we sought to identify pericytic miRNAs that could serve as a target to decrease myofibroblast formation. Kidney fibrosis was induced in FoxD1-GC;Z/Red-mice by unilateral ureteral obstruction followed by FACS sorting of dsRed-positive FoxD1-derivative cells and miRNA profiling. MiR-132 selectively increased 21-fold during pericyte-to-myofibroblast formation, whereas miR-132 was only 2.5-fold up in total kidney lysates (both in obstructive and ischemia-reperfusion injury). MiR-132 silencing during obstruction decreased collagen deposition (35%) and tubular apoptosis. Immunohistochemistry, Western blot, and qRT-PCR confirmed a similar decrease in interstitial α-SMA(+) cells. Pathway analysis identified a rate-limiting role for miR-132 in myofibroblast proliferation that was confirmed in vitro. Indeed, antagomir-132-treated mice displayed a reduction in the number of proliferating Ki67(+) interstitial myofibroblasts. Interestingly, this was selective for the interstitial compartment and did not impair the reparative proliferation of tubular epithelial cells, as evidenced by an increase in Ki67(+) epithelial cells, as well as increased phospho-RB1, Cyclin-A and decreased RASA1, p21 levels in kidney lysates. Additional pathway and gene expression analyses suggest miR-132 coordinately regulates genes involved in TGF-β signaling (Smad2/Smad3), STAT3/ERK pathways, and cell proliferation (Foxo3/p300). Thus, silencing miR-132 counteracts the progression of renal fibrosis by selectively decreasing myofibroblast proliferation and could potentially serve as a novel antifibrotic therapy.

Topics: Actins; Animals; Antagomirs; Apoptosis; Cell Line; Cell Proliferation; Collagen; Epithelial Cells; Fibroblasts; Fibrosis; Humans; Immunohistochemistry; Kidney; Kidney Tubules; Mice; Mice, Inbred C57BL; MicroRNAs; Myofibroblasts; Pericytes; Renal Insufficiency, Chronic; Reverse Transcriptase Polymerase Chain Reaction; RNA Interference; Signal Transduction; Transforming Growth Factor beta

Endothelial-to-mesenchymal transition (EndoMT) is a crucial event during kidney interstitial fibrosis and it is believed to be inhibited by netrin-1. Our aim was to determine the influence of netrin-1 on renal EndoMT in chronic kidney disease by studying its effect in 5/6 nephrectomized (Nx) rats.. Male Sprague-Dawley rats were divided into three groups (10 rats/group): sham-operated rats treated with control adenovirus; 5/6 Nx rats treated with control adenovirus; and 5/6 Nx rats treated with recombinant adenovirus expressing the netrin-1 gene (Ad-netrin-1). Rats were sacrificed 13 weeks after surgery. Blood urea nitrogen (BUN) and serum creatinine (Scr) levels were measured regularly after surgery. After the rats were sacrificed, pathological changes in renal tissues were analyzed histologically. Immunofluorescence was performed to evaluate the co-expression of CD31 and α-SMA. CD31, α-SMA and Snail mRNA were detected by RT-PCR. Protein expression was detected by western blot.. Renal function and histopathological damage were significantly improved in Ad-netrin-1-treated 5/6 Nx rats. In the sham and control-treated 5/6 Nx rats, the percentage of CD31(+)/α-SMA(+) cells increased, which indicated EndoMT. However, the percentage of CD31(+)/α-SMA(+) cells were reduced in the netrin-1-treated 5/6 Nx rats, which indicates netrin-1-induced blocking of EndoMT.. From the results, it seems that netrin-1 attenuates the progression of renal dysfunction by inhibiting EndoMT in 5/6 Nx rats. Netrin-1 can therefore be considered as a potential therapeutic agent for the treatment of renal fibrosis.

Topics: Actins; Animals; Blood Urea Nitrogen; Creatinine; Endothelium; Epithelial-Mesenchymal Transition; Fibrosis; Kidney; Male; Nephrectomy; Netrin-1; Platelet Endothelial Cell Adhesion Molecule-1; Rats; Rats, Sprague-Dawley; Renal Insufficiency, Chronic; RNA, Messenger; Signal Transduction; Snail Family Transcription Factors; Transforming Growth Factor beta

CKD is a global public health problem with significant mortality and morbidity.. We examined the multivariable association of plasma levels of IL-1, IL-1 receptor antagonist, IL-6, TNF-α, TGF-β, high-sensitivity C-reactive protein, fibrinogen, and serum albumin with progression of CKD in 3430 Chronic Renal Insufficiency Cohort study participants.. Over a median follow-up time of 6.3 years, 899 participants reached the composite end point of ≥50% decline in eGFR from baseline or onset of ESRD. Elevated plasma levels of fibrinogen, IL-6, and TNF-α and lower serum albumin were associated with a greater decline in eGFR over time. After adjusting for demographics, BP, laboratory variables, medication use, and baseline eGFR, hazard ratios for the composite outcome were greater for the patients in the highest quartile of fibrinogen (hazard ratio, 2.05; 95% confidence interval, 1.64 to 2.55; P<0.001), IL-6 (hazard ratio, 1.44; 95% confidence interval, 1.17 to 1.77; P<0.01), and TNF-α (hazard ratio, 1.94; 95% confidence interval, 1.52 to 2.47; P<0.001) compared with those in the respective lowest quartiles. The hazard ratio was 3.48 (95% confidence interval, 2.88 to 4.21; P<0.001) for patients in the lowest serum albumin quartile relative to those in the highest quartile. When also adjusted for albuminuria, the associations of fibrinogen (hazard ratio, 1.49; 95% confidence interval, 1.20 to 1.86; P<0.001), serum albumin (hazard ratio, 1.52; 95% confidence interval, 1.24 to 1.87; P<0.001), and TNF-α (hazard ratio, 1.42; 95% confidence interval, 1.11 to 1.81; P<0.001) with outcome were attenuated but remained significant.. Elevated plasma levels of fibrinogen and TNF-α and decreased serum albumin are associated with rapid loss of kidney function in patients with CKD.

Topics: Adult; Aged; C-Reactive Protein; Cytokines; Disease Progression; Female; Fibrinogen; Follow-Up Studies; Glomerular Filtration Rate; Humans; Inflammation; Interleukin-1; Interleukin-6; Kidney Failure, Chronic; Male; Middle Aged; Renal Insufficiency, Chronic; Serum Albumin; Transforming Growth Factor beta; Tumor Necrosis Factor-alpha

Age is associated with an increased prevalence of chronic kidney disease (CKD), which, through progressive tissue damage and fibrosis, ultimately leads to loss of kidney function. Although much effort is put into studying CKD development experimentally, age has rarely been taken into account. Therefore, we investigated the effect of age on the development of renal tissue damage and fibrosis in a mouse model of obstructive nephropathy (i.e., unilateral ureter obstruction; UUO). We observed that after 14 days, obstructed kidneys of old mice had more tubulointerstitial atrophic damage but less fibrosis than those of young mice. This was associated with reduced connective tissue growth factor (CTGF), and higher bone morphogenetic protein 6 (BMP6) expression and pSMAD1/5/8 signaling, while transforming growth factor-β expression and transcriptional activity were no different in obstructed kidneys of old and young mice. In vitro, CTGF bound to and inhibited BMP6 activity. In summary, our data suggest that in obstructive nephropathy atrophy increases and fibrosis decreases with age and that this relates to increased BMP signaling, most likely due to higher BMP6 and lower CTGF expression.

Topics: Age Factors; Animals; Bone Morphogenetic Protein 6; Connective Tissue Growth Factor; Disease Models, Animal; Fibrosis; Kidney; Mice; Phosphorylation; Renal Insufficiency, Chronic; Signal Transduction; Smad Proteins; Transforming Growth Factor beta; Ureteral Obstruction

Chronic kidney disease (CKD) results from the development of fibrosis, ultimately leading to end-stage renal disease (ESRD). Although human bone marrow-derived mesenchymal stem cells (MSCs) can accelerate renal repair following acute injury, the establishment of fibrosis during CKD may affect their potential to influence regeneration capacity. Here we tested the novel combination of MSCs with the antifibrotic serelaxin to repair and protect the kidney 7 d post-unilateral ureteral obstruction (UUO), when fibrosis is established. Male C57BL6 mice were sham-operated or UUO-inured (n = 4-6) and received vehicle, MSCs (1 × 10(6)), serelaxin (0.5 mg/kg per d), or the combination of both. In vivo tracing studies with luciferin/enhanced green fluorescent protein (eGFP)-tagged MSCs showed specific localization in the obstructed kidney where they remained for 36 h. Combination therapy conferred significant protection from UUO-induced fibrosis, as indicated by hydroxyproline analysis (P < 0.001 vs. vehicle, P < 0.05 vs. MSC or serelaxin alone). This was accompanied by preserved structural architecture, decreased tubular epithelial injury (P < 0.01 vs. MSCs alone), macrophage infiltration, and myofibroblast localization in the kidney (both P < 0.01 vs. vehicle). Combination therapy also stimulated matrix metalloproteinase (MMP)-2 activity over either treatment alone (P < 0.05 vs. either treatment alone). These results suggest that the presence of an antifibrotic in conjunction with MSCs ameliorates established kidney fibrosis and augments tissue repair to a greater extent than either treatment alone.

Topics: Animals; Cell Differentiation; Cell Proliferation; Collagen; Fibrosis; Gelatinases; Green Fluorescent Proteins; Humans; Kidney; Kidney Failure, Chronic; Macrophages; Male; Matrix Metalloproteinase 2; Mesenchymal Stem Cells; Mice; Mice, Inbred C57BL; Myofibroblasts; Recombinant Proteins; Regeneration; Relaxin; Renal Insufficiency, Chronic; Transforming Growth Factor beta

Topics: Animals; Cell Transdifferentiation; Endothelium; Kidney; Renal Insufficiency, Chronic; Transforming Growth Factor beta

Excessive TGF-β signaling in epithelial cells, pericytes, or fibroblasts has been implicated in CKD. This list has recently been joined by endothelial cells (ECs) undergoing mesenchymal transition. Although several studies focused on the effects of ablating epithelial or fibroblast TGF-β signaling on development of fibrosis, there is a lack of information on ablating TGF-β signaling in the endothelium because this ablation causes embryonic lethality. We generated endothelium-specific heterozygous TGF-β receptor knockout (TβRII(endo+/-)) mice to explore whether curtailed TGF-β signaling significantly modifies nephrosclerosis. These mice developed normally, but showed enhanced angiogenic potential compared with TβRII(endo+/+) mice under basal conditions. After induction of folic acid nephropathy or unilateral ureteral obstruction, TβRII(endo+/-) mice exhibited less tubulointerstitial fibrosis, enhanced preservation of renal microvasculature, improvement in renal blood flow, and less tissue hypoxia than TβRII(endo+/+) counterparts. In addition, partial deletion of TβRII in the endothelium reduced endothelial-to-mesenchymal transition (EndoMT). TGF-β-induced canonical Smad2 signaling was reduced in TβRII(+/-) ECs; however, activin receptor-like kinase 1 (ALK1)-mediated Smad1/5 phosphorylation in TβRII(+/-) ECs remained unaffected. Furthermore, the S-endoglin/L-endoglin mRNA expression ratio was significantly lower in TβRII(+/-) ECs compared with TβRII(+/+) ECs. These observations support the hypothesis that EndoMT contributes to renal fibrosis and curtailing endothelial TGF-β signals favors Smad1/5 proangiogenic programs and dictates increased angiogenic responses. Our data implicate endothelial TGF-β signaling and EndoMT in regulating angiogenic and fibrotic responses to injury.

Topics: Animals; Cell Transdifferentiation; Endoglin; Endothelium; Fibrosis; Folic Acid; Intracellular Signaling Peptides and Proteins; Kidney; Mice, Transgenic; Neovascularization, Physiologic; Protein Serine-Threonine Kinases; Receptor, Transforming Growth Factor-beta Type II; Receptors, Transforming Growth Factor beta; Renal Insufficiency, Chronic; Smad Proteins; Transforming Growth Factor beta; Ureteral Obstruction

Aristolochic acids (AA) are nephrotoxic and profibrotic agents, leading to chronic kidney disease. As some controversial studies have reported a nephroprotective effect of exogenous recombinant human bone morphogenetic protein (rhBMP)-7 in several models of renal fibrosis, we investigated the putative effect of rhBMP-7 to prevent progressive tubulointerstitial damage after AA intoxication in vitro and in vivo. In vitro, the toxicity of AA on renal tubular cells was demonstrated by an increase in vimentin as well as a decrease in β-catenin expressions, reflecting a dedifferentiation process. Increased fibronectin and interleukin-6 levels were measured in the supernatants. Enhanced α-SMA mRNA levels associated to decreased E-cadherin mRNA levels were also measured. Incubation with rhBMP-7 only prevented the increase in vimentin and the decrease in β-catenin expressions. In vivo, in a rat model of AA nephropathy, severe tubulointerstitial lesions induced by AA after 10 and 35 days (collagen IV deposition and tubular atrophy), were not prevented by the rhBMP-7 treatment. Similarly, rhBMP-7 did not ameliorate the significant increase in urinary concentrations of transforming growth factor-β. In summary, our in vitro data demonstrated a poor beneficial effect of rhBMP-7 to reverse cell toxicity while, in vivo, there was no beneficial effect of rhBMP-7. Therefore, further investigations are needed to confirm the exact role of BMP-7 in progressive chronic kidney disease.

Topics: Animals; Aristolochic Acids; beta Catenin; Bone Morphogenetic Protein 7; Cell Line; Fibronectins; Fibrosis; Humans; Kidney; Male; Rats, Wistar; Recombinant Proteins; Renal Insufficiency, Chronic; Transforming Growth Factor beta; Treatment Outcome; Vimentin

In traditional Chinese medicine, Tanshinone IIA is used to treat chronic kidney disease (CKD). However, its biological activity and mechanism of action in renal fibrosis and inflammation are not fully identified. The current study was conducted to determine the effects of Tanshinone IIA treatment on CKD by assessing potential modulation of the TGF-β/Smad and NF-κB signaling pathway.. CKD was produced in rats by 5/6 nephrectomy. They were then divided into the following groups: control (sham operation); CKD (5/6 nephrectomy); 5/6 nephrectomy+Tanshinone IIA (10mg/kg in average, once a day for 16 weeks). Serum and urine samples were obtained from animals in each group, and serum creatinine (Scr), blood urea nitrogen (BUN) levels and 24h urinary protein excretion were measured. Tissue samples from the kidney were used for morphometric studies (Masson's trichrome). The expression of fibronectin protein and collagen types I, III, IV, and TGF-β, TNF-α, CXCL-1, MCP-1, RANTES mRNA were evaluated using immunohistochemistry and RT-PCR analysis; the TGF-β/Smad and NF-κB signaling pathway was detected by immunohistochemistry and Western blot analysis.. The following effects were observed in CKD rats treated with Tanshinone IIA: (1) marked improvements in Scr, and 24h urine protein excretion; (2) significant reductions in protein and mRNA levels of fibronectin, collagen III, and collagen IV and TNF-α, MCP-1, and CXCL-1; (3) significantly inhibited the TGF-β/Smad and NF-κB signaling activation.. These results suggest that Tanshinone IIA suppresses renal fibrosis and inflammation via altering expression of TGF-β/Smad and NF-κB pathway in the remnant kidney, thus supporting the potential of Tanshinone IIA as a new therapeutic agent for slowing the progression of CKD.

Topics: Abietanes; Animals; Blotting, Western; Disease Models, Animal; Drugs, Chinese Herbal; Fibrosis; Gene Expression; Immunohistochemistry; Kidney; Kidney Function Tests; Male; Medicine, Chinese Traditional; Nephrectomy; NF-kappa B; Rats, Sprague-Dawley; Real-Time Polymerase Chain Reaction; Renal Insufficiency, Chronic; Signal Transduction; Smad Proteins; Transforming Growth Factor beta

Obstructive nephropathy is the leading cause of kidney disease in children. The tissue injury resulting from initial dilation precipitates a deleterious cascade of macrophage infiltration, apoptosis, and fibrosis to produce a resultant dysfunctional tissue. We propose to abate this tissue remodeling process through immunotherapy administered via the local and sustained delivery of interleukin-10 (IL-10; anti-inflammatory) and anti-transforming growth factor β (anti-TGFβ; anti-fibrotic). Shear-thinning, injectable hyaluronic acid (HA) hydrogels were formed through supramolecular guest-host interactions and used to contain IL-10, anti-TGFβ, or both molecules together. Degradation assays demonstrated that diffusive molecule release was associated with concurrent hydrogel erosion and was sustained for up to 3weeks in vitro. Erosion was likewise monitored in vivo by non-invasive optical imaging, where gel localization to the affected tissue was observed with near complete clearance by day 18. Hydrogels were applied to a murine model of chronic kidney disease, with subcapsular hydrogel injections acting as a delivery depot. Quantitative histological analysis (days 7, 21, and 35) was used to evaluate treatment efficacy. Notably, results demonstrated reduced macrophage infiltration beyond day 7 in treatment groups and reduced apoptosis at day 21, relative to untreated unilateral ureteral obstruction disease model. Fibrosis was reduced at the 35day timepoint in groups treated with IL-10 or anti-TGFβ alone, but not with the combination therapy. Rather, dual delivery of IL-10 and anti-TGFβ resulted in a paradoxical hastening of fibrosis, warranting further investigation. Localized immunotherapy is a novel approach to treat kidney disease and shows promise as a translatable therapy.

Topics: Animals; Anti-Inflammatory Agents; Delayed-Action Preparations; Drug Delivery Systems; Fibrosis; Humans; Hyaluronic Acid; Hydrogels; Immunotherapy; Interleukin-10; Kidney; Mice; Mice, Inbred BALB C; Renal Insufficiency, Chronic; Transforming Growth Factor beta

The purpose of this study is to investigate the antifibrosis and antioxidation of ShenKang injection (SKI) in vivo and in vitro and to evaluate potential mechanisms involved in the treatment of chronic kidney disease (CKD).. In experimental animal studies, CKD was established by 5/6 nephrectomy (5/6Nx). Serum creatinine (Scr) and blood urea nitrogen (BUN) were determined. Histopathological tests were performed by H&E and Masson trichrome stained. The protein expressions of fibronectin (FN), collagen Ι, α-smooth muscle actin (α-SMA) and transforming growth factor-β (TGF-β) and phosphorylation of Smad3 were measured in 5/6Nx rats. In Human kidney proximal tubular cell line (HK-2) cells, the effects of TGF-β/Smad3 signalling pathway on renal fibrosis and oxidative injury were examined.. 5/6Nx induced severe renal damages. Treatment of rats with SKI markedly reduced levels of Scr and BUN, alleviated expression of fibrosis-associated signalling molecules and reduced expression of TGF-β and phosphorylated Smad3. Meanwhile, in HK-2 cells, after exposure to TGF-β and H2 O2 , the protein expression of renal fibrosis was significantly increased. The generation of oxidative stress was also elevated. The severity of fibrosis and oxidative damage appears to be reduced after treatment with SKI.. SKI inhibits renal fibrosis and oxidative stress through downregulation of TGF-β/Smad3 signalling pathway.

Topics: Animals; Blood Urea Nitrogen; Cell Line; Creatinine; Disease Models, Animal; Dose-Response Relationship, Drug; Drugs, Chinese Herbal; Enalapril; Fibrosis; Glyceraldehyde-3-Phosphate Dehydrogenases; Humans; Hydrogen Peroxide; Male; Oxidative Stress; Rats; Rats, Sprague-Dawley; Renal Insufficiency, Chronic; Signal Transduction; Smad3 Protein; Transforming Growth Factor beta

Hemodialysis as an efficient therapy for advanced CKD is the most used treatment modality all over the world. Even though primary AVF is widely accepted as a best permanent vascular access in hemodialysis patients, up to 60% of all fistulas fail to mature. The pathogenesis of early fistula failure is not very well understood. Many general and local factors are involved: patient's age, sex, primary renal disease, small vessel's diameter, presence of accessory veins, prior venipunctures, surgical skill, genetics, etc. Histological investigations have confirmed the neointimal venous hyperplasia as a major pathological finding in stenotic lesions of AVF failure, due to local inflammation, oxidative stress and migration and proliferation of myofibroblasts, fibroblasts and endothelial cells.. A total of 89 patients with stadium 4-5 of CKD are involved in the study. A typical radio-cephalic AVF is created in all patients. Part of the fistula vein was taken for histological, immunohistochemical (Vimentin, TGF β and KI67) and morphometric analysis. Appriopriate statistical method was applied.. Up to 80% of the patients showed some degree of endothelial changes at the time of creation of AVF, among them 19 pts with substantial intimal hyperplasia, 51 with medial hypertrophy and 19 pts with normal histology. Almost two thirds of the patients did not have expression of TGFβ. More than 95% had some expression of Vimentin. None of the patients had expression of the marker KI 67.. Medial hypertrophy is predominant preexisting pathohistological lesion prior the AVF creation, despite the presence of neointimal hyperplasia. The absence of TGFβ expression in majority of our patients could suggest that inflammation and oxidative stress are developing later, after vascular access surgery. The dominant cells within the stenosis in the veins are myofibroblasts. Their increased presence maybe a reason why some patients are prone to developing venous endothelial changes as a results of exaggerated vascular endothelial response to the effect of uremia, hypertension and other insults.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Arteriovenous Shunt, Surgical; Biomarkers; Endothelial Cells; Female; Graft Occlusion, Vascular; Humans; Hyperplasia; Hypertrophy; Immunohistochemistry; Ki-67 Antigen; Male; Middle Aged; Neointima; Prospective Studies; Radial Artery; Renal Dialysis; Renal Insufficiency, Chronic; Risk Factors; Severity of Illness Index; Transforming Growth Factor beta; Treatment Failure; Veins; Vimentin; Young Adult

Renal tubulointerstitial fibrosis is the common end point of progressive renal disease. MicroRNA (miR)-214 and miR-21 are upregulated in models of renal injury, but the function of miR-214 in this setting and the effect of its manipulation remain unknown. We assessed the effect of inhibiting miR-214 in an animal model of renal fibrosis. In mice, genetic deletion of miR-214 significantly attenuated interstitial fibrosis induced by unilateral ureteral obstruction (UUO). Treatment of wild-type mice with an anti-miR directed against miR-214 (anti-miR-214) before UUO resulted in similar antifibrotic effects, and in vivo biodistribution studies demonstrated that anti-miR-214 accumulated at the highest levels in the kidney. Notably, in vivo inhibition of canonical TGF-β signaling did not alter the regulation of endogenous miR-214 or miR-21. Whereas miR-21 antagonism blocked Smad 2/3 activation, miR-214 antagonism did not, suggesting that miR-214 induces antifibrotic effects independent of Smad 2/3. Furthermore, TGF-β blockade combined with miR-214 deletion afforded additional renal protection. These phenotypic effects of miR-214 depletion were mediated through broad regulation of the transcriptional response to injury, as evidenced by microarray analysis. In human kidney tissue, miR-214 was detected in cells of the glomerulus and tubules as well as in infiltrating immune cells in diseased tissue. These studies demonstrate that miR-214 functions to promote fibrosis in renal injury independent of TGF-β signaling in vivo and that antagonism of miR-214 may represent a novel antifibrotic treatment in the kidney.

Topics: Animals; Disease Models, Animal; Fibrosis; Gene Deletion; Gene Expression; Humans; Imidazoles; Kidney; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; MicroRNAs; Quinoxalines; Renal Insufficiency, Chronic; Signal Transduction; Smad2 Protein; Smad3 Protein; Transforming Growth Factor beta; Ureteral Obstruction

1. Chronic oxidative stress and inflammation are major mediators of chronic kidney disease (CKD) and result in impaired activation of the cytoprotective transcription factor Nrf2. Given the role of oxidative stress and inflammation in CKD pathogenesis, strategies aimed at restoring Nrf2 activity may attenuate CKD progression. 2. The present study investigated whether the synthetic triterpenoid RTA dh404 (2-cyano-3,12-dioxooleana-1,9-dien-28-oic acid-9,11-dihydro-trifluoroethyl amide or CDDO-dhTFEA) would afford renal protection in a 5/6 nephrectomized rat model of CKD. RTA dh404 (2 mg/kg/day) was orally administered once daily for 12 weeks after 5/6 nephrectomy surgery. 3. The remnant kidneys from the vehicle-treated CKD rats showed activation of nuclear factor kappaB (NF-κB), upregulation of NAD(P)H oxidase, glomerulosclerosis, interstitial fibrosis and inflammation, as well as marked reductions in Nrf2 and its target gene products (i.e. catalase, heme oxygenase-1, thioredoxin 1, thioredoxin reductase 1 and peroxiredoxin 1). The functional and structural deficits in the kidney were associated with increased (∼30%) mean arterial pressure (MAP). Treatment with RTA dh404 restored MAP, increased Nrf2 and expression of its target genes, attenuated activation of NF-κB and transforming growth factor-β pathways, and reduced glomerulosclerosis, interstitial fibrosis and inflammation in the CKD rats. 4. Thus, chronic treatment with RTA dh404 was effective in restoring Nrf2 activity and slowing CKD progression in rats following 5/6 nephrectomy.

Topics: Animals; Blotting, Western; Extracellular Signal-Regulated MAP Kinases; Fibrosis; Gene Expression Regulation; Inflammation; Intracellular Signaling Peptides and Proteins; Kelch-Like ECH-Associated Protein 1; Kidney; Male; NF-E2-Related Factor 2; Oleanolic Acid; Oxidative Stress; Rats, Sprague-Dawley; Renal Insufficiency, Chronic; RNA, Messenger; Signal Transduction; Smad7 Protein; Transforming Growth Factor beta

Patients with CKD have an increased risk of cardiovascular mortality from arrhythmias and sudden cardiac death. We used a rat model of CKD (Cy/+) to study potential mechanisms of increased ventricular arrhythmias. Rats with CKD showed normal ejection fraction but hypertrophic myocardium. Premature ventricular complexes occurred more frequently in CKD rats than normal rats (42% versus 11%, P=0.18). By optical mapping techniques, action potential duration (APD) at 80% of repolarization was longer in CKD rats (78±4ms) than normal rats (63±3 ms, P<0.05) at a 200-ms pacing cycle length. Calcium transient (CaT) duration was comparable. Pacing cycle length thresholds to induce CaT alternans or APD alternans were longer in CKD rats than normal rats (100±7 versus 80±3 ms and 93±6 versus 76±4 ms for CaT and APD alternans, respectively, P<0.05), suggesting increased vulnerability to ventricular arrhythmia. Ventricular fibrillation was induced in 9 of 12 CKD rats and 2 of 9 normal rats (P<0.05); early afterdepolarization occurred in two CKD rats but not normal rats. The mRNA levels of TGF-β, microRNA-21, and sodium calcium-exchanger type 1 were upregulated, whereas the levels of microRNA-29, L-type calcium channel, sarco/endoplasmic reticulum calcium-ATPase type 2a, Kv1.4, and Kv4.3 were downregulated in CKD rats. Cardiac fibrosis was mild and not different between groups. We conclude that cardiac ion channel and calcium handling are abnormal in CKD rats, leading to increased vulnerability to early afterdepolarization, triggered activity, and ventricular arrhythmias.

Topics: Action Potentials; Animals; Arrhythmias, Cardiac; Calcium; Calcium Signaling; Disease Models, Animal; Echocardiography; Electrophysiology; Fibrosis; Gene Expression Regulation; Heart Rate; Male; MicroRNAs; Myocardium; Rats; Renal Insufficiency, Chronic; RNA, Messenger; Transforming Growth Factor beta; Ventricular Fibrillation

Despite a significant improvement in the management of chronic kidney disease (CKD), its incidence and prevalence has been increasing over the years. Progressive renal fibrosis is present in CKD and involves the participation of several cytokines, including Transforming growth factor-β1 (TGF-β1). Besides cardiovascular diseases and infections, several studies show that Vitamin D status has been considered as a non-traditional risk factor for the progression of CKD. Given the importance of vitamin D in the maintenance of essential physiological functions, we studied the events involved in the chronic kidney disease progression in rats submitted to ischemia/reperfusion injury under vitamin D deficiency (VDD).. Rats were randomized into four groups: Control; VDD; ischemia/reperfusion injury (IRI); and VDD+IRI. At the 62 day after sham or IRI surgery, we measured inulin clearance, biochemical variables and hemodynamic parameters. In kidney tissue, we performed immunoblotting to quantify expression of Klotho, TGF-β, and vitamin D receptor (VDR); gene expression to evaluate renin, angiotensinogen, and angiotensin-converting enzyme; and immunohistochemical staining for ED1 (macrophages), type IV collagen, fibronectin, vimentin, and α-smooth mucle actin. Histomorphometric studies were performed to evaluate fractional interstitial area.. IRI animals presented renal hypertrophy, increased levels of mean blood pressure and plasma PTH. Furthermore, expansion of the interstitial area, increased infiltration of ED1 cells, increased expression of collagen IV, fibronectin, vimentin and α-actin, and reduced expression of Klotho protein were observed. VDD deficiency contributed to increased levels of plasma PTH as well as for important chronic tubulointerstitial changes (fibrosis, inflammatory infiltration, tubular dilation and atrophy), increased expression of TGF-β1 and decreased expression of VDR and Klotho protein observed in VDD+IRI animals.. Through inflammatory pathways and involvement of TGF-β1 growth factor, VDD could be considered as an aggravating factor for tubulointerstitial damage and fibrosis progression following acute kidney injury induced by ischemia/reperfusion.

Topics: Actins; Acute Kidney Injury; Angiotensinogen; Animals; Disease Progression; Fibronectins; Kidney; Male; Rats; Rats, Wistar; Receptors, Calcitriol; Renal Insufficiency, Chronic; Renin; Reperfusion Injury; Transforming Growth Factor beta; Transforming Growth Factor beta1; Vitamin D Deficiency

Bone morphogenetic protein 1 (BMP1) was originally isolated from bone with other BMPs due to its affinity for heparin. While all other BMPs are members of the Transforming Growth Factor β (TGFβ) superfamily of growth factors, BMP1 is not an authentic member of the BMP protein family. Together with mammalian Tolloid Like protein 1 (mTLL-1) and mTLL-2, BMP1 comprise a small group of zinc- and calcium-dependent proteinases. Acute myocardial infarction (AMI) is the leading cause of death in developed countries which accounts for 13% of deaths worldwide. It was recently shown that inhibition of BMP1-3 reduces progression of fibrosis in chronic kidney disease and suggested that BMP1-3 is an important molecule for fibrogenesis. We hypothesize that inhibition of BMP1-3 represents future of therapeutic interventions in the heart tissue fibrosis following AMI. This novel approach aims to acquire the first candidate specific treatment for recuperating the heart function in patients with AMI.

Topics: Antibodies, Monoclonal; Bone Morphogenetic Protein 1; Cicatrix; Disease Progression; Fibrosis; Humans; Models, Theoretical; Myocardial Infarction; Myocardium; Renal Insufficiency, Chronic; Tolloid-Like Metalloproteinases; Transforming Growth Factor beta

The secreted kielin/chordin-like (KCP) protein, one of a family of cysteine-rich proteins, suppresses TGF-β signaling by sequestering the ligand from its receptor, but it enhances bone morphogenetic protein (BMP) signaling by promoting ligand-receptor interactions. Given the critical roles for TGF-β and BMP proteins in enhancing or suppressing renal interstitial fibrosis, respectively, we examined whether secreted KCP could attenuate renal fibrosis in mouse models of chronic and acute disease. Transgenic mice that express KCP in adult kidneys showed significantly less expression of collagen IV, α-smooth muscle actin, and other markers of disease progression in the unilateral ureteral obstruction model of renal interstitial fibrosis. In the folic acid nephrotoxicity model of acute tubular necrosis, mice expressing KCP survived high doses of folic acid that were lethal for wild-type mice. With a lower dose of folic acid, mice expressing KCP exhibited improved renal recovery compared with wild-type mice. Thus, these data suggest that extracellular regulation of the TGF-β/BMP signaling axis by KCP, and by extension possibly other cysteine-rich domain proteins, can attenuate both acute and chronic renal injury.

Topics: Acute Kidney Injury; Animals; Carrier Proteins; Disease Progression; Epithelial Cells; Female; Fibrosis; Gene Expression Regulation, Developmental; Kidney Tubular Necrosis, Acute; Mice; Mice, Transgenic; Primary Cell Culture; Protein Structure, Tertiary; Renal Insufficiency, Chronic; Signal Transduction; Transforming Growth Factor beta; Transgenes

Hypertension is a risk factor for chronic kidney disease, particularly when associated with impaired renal autoregulation and thereby increased intraglomerular pressure (Pgc). Elevated Pgc can be modeled in vitro by exposing glomerular mesangial cells to mechanical strain. We previously showed that RhoA mediates strain-induced matrix production. Here, we show that RhoA activation is dependent on an intact microtubule network. Upregulation of the profibrotic cytokine connective tissue growth factor (CTGF) by mechanical strain is dependent on RhoA activation and inhibited by microtubule disruption. We tested the effects of the microtubule depolymerizing agent colchicine in 5/6 nephrectomized rats, a model of chronic kidney disease driven by elevated Pgc. Colchicine inhibited glomerular RhoA activation and attenuated both glomerular sclerosis and interstitial fibrosis without affecting systemic blood pressure. Upregulation of the matrix proteins collagen I and fibronectin, as well as CTGF, was attenuated by colchicine. Activity of the profibrotic cytokine TGF-β, as assessed by Smad3 phosphorylation, was also inhibited by colchicine. Microtubule disruption significantly decreased renal infiltration of lymphocytes and macrophages. Our studies thus indicate that colchicine modifies hypertensive renal fibrosis. Its protective effects are likely mediated by inhibition of RhoA signaling and renal infiltration of inflammatory cells. Already well-established in clinical practice for other indications, prevention of hypertension-associated renal fibrosis may represent a new potential use for colchicine.

Topics: Animals; Cells, Cultured; Colchicine; Collagen Type I; Connective Tissue Growth Factor; Cytoprotection; Disease Models, Animal; Enzyme Activation; Fibronectins; Fibrosis; Hypertension, Renal; Kidney; Male; Microtubules; Nephrectomy; Nephritis; Phosphorylation; Promoter Regions, Genetic; Rats; Rats, Sprague-Dawley; Renal Insufficiency, Chronic; rhoA GTP-Binding Protein; Smad3 Protein; Stress, Mechanical; Transfection; Transforming Growth Factor beta

Dendritic cells (DCs) play critical roles in immune-mediated kidney diseases. Little is known, however, about DC subsets in human chronic kidney disease, with previous studies restricted to a limited set of pathologies and to using immunohistochemical methods. In this study, we developed novel protocols for extracting renal DC subsets from diseased human kidneys and identified, enumerated, and phenotyped them by multicolor flow cytometry. We detected significantly greater numbers of total DCs as well as CD141(hi) and CD1c(+) myeloid DC (mDCs) subsets in diseased biopsies with interstitial fibrosis than diseased biopsies without fibrosis or healthy kidney tissue. In contrast, plasmacytoid DC numbers were significantly higher in the fibrotic group compared with healthy tissue only. Numbers of all DC subsets correlated with loss of kidney function, recorded as estimated glomerular filtration rate. CD141(hi) DCs expressed C-type lectin domain family 9 member A (CLEC9A), whereas the majority of CD1c(+) DCs lacked the expression of CD1a and DC-specific ICAM-3-grabbing nonintegrin (DC-SIGN), suggesting these mDC subsets may be circulating CD141(hi) and CD1c(+) blood DCs infiltrating kidney tissue. Our analysis revealed CLEC9A(+) and CD1c(+) cells were restricted to the tubulointerstitium. Notably, DC expression of the costimulatory and maturation molecule CD86 was significantly increased in both diseased cohorts compared with healthy tissue. Transforming growth factor-β levels in dissociated tissue supernatants were significantly elevated in diseased biopsies with fibrosis compared with nonfibrotic biopsies, with mDCs identified as a major source of this profibrotic cytokine. Collectively, our data indicate that activated mDC subsets, likely recruited into the tubulointerstitium, are positioned to play a role in the development of fibrosis and, thus, progression to chronic kidney disease.

Topics: Aged; Antigens, CD1; Antigens, Surface; Biomarkers; Biopsy; Case-Control Studies; Cell Count; Chemotaxis; Cytokines; Dendritic Cells; Disease Progression; Female; Fibrosis; Flow Cytometry; Glycoproteins; Humans; Immunophenotyping; Inflammation Mediators; Kidney; Lectins, C-Type; Male; Middle Aged; Myeloid Cells; Receptors, Mitogen; Renal Insufficiency, Chronic; Thrombomodulin; Transforming Growth Factor beta

Acute kidney injury (AKI) has been recognized as a risk factor for the development of chronic kidney disease (CKD). Aldosterone has a critical role in promoting renal injury induced by ischemia. Here, we evaluated whether spironolactone administered before or after AKI caused by ischemia protects against CKD. In the first set of experiments, Wistar rats underwent a sham operation without or with prior spironolactone treatment, or underwent 45 minutes of bilateral renal ischemia without or with spironolactone treatment before ischemia and assessed over 270 days. The second set of rats received low (20 mg/kg) or high (80 mg/kg) doses of spironolactone at three different times after the sham operation or bilateral renal ischemia and were assessed after 90 days. Untreated animals developed CKD following ischemia-induced AKI as characterized by a progressive increase in proteinuria, renal dysfunction, podocyte injury, glomerular hypertrophy, and focal sclerosis. This was associated with increased oxidative stress, an upregulation of tumor growth factor (TGF)-β, followed by upregulation of the TGF-β downstream effectors phospho-Smad3, collagen I, fibronectin, and proinflammatory cytokines. Treatment with spironolactone either before or after ischemia prevented subsequent CKD by avoiding the activation of fibrotic and inflammatory pathways. Thus, spironolactone may be a promising treatment for the prevention of AKI-induced CKD.

Topics: Acute Kidney Injury; Animals; Collagen Type I; Disease Models, Animal; Diuretics; Dose-Response Relationship, Drug; Fibronectins; Ischemia; Kidney; Male; Mineralocorticoid Receptor Antagonists; Oxidative Stress; Rats; Rats, Wistar; Renal Insufficiency, Chronic; Spironolactone; Transforming Growth Factor beta

Imatinib is a selective tyrosine kinase inhibitor that can block platelet-derived growth factor (PDGF) receptor activity. Imatinib is also known as an anti-inflammatory agent. We examined the therapeutic effects of long- or short-term imatinib treatment in Wistar-Kyoto (WKY) rats with established anti-glomerular basement membrane (GBM) nephritis.. Nephrotoxic serum (NTS) nephritis was induced in WKY rats on day 0. Groups of animals were given either imatinib or vehicle daily by intraperitoneal injection, from day 7 to day 49 in the long-term treatment study, and from day 7 to 13 in the short-term treatment study; all rats were sacrificed at day 50.. In long-term treatment, imatinib showed marked renoprotective effects; imatinib suppressed proteinuria, improved renal function, attenuated the development of glomerulosclerosis and tubulointerstitial injury and reduced the expression levels of collagen type I and transforming growth factor-beta (TGF-β) in renal cortex. The key finding of the present study was that short-term treatment with imatinib also significantly attenuated the development of renal injury until day 50, although the degree of renoprotection was slightly inferior to that of long-term treatment.. These results suggest that administration of imatinib is a promising strategy for limiting the progression of glomerulonephritis (GN) to end-stage renal failure. In particular, a short period of treatment at an early stage of GN is more beneficial in terms of cost-effectiveness and reduction of adverse effects in comparison to a continuous and long period of treatment.

Topics: Animals; Anti-Glomerular Basement Membrane Disease; Benzamides; Collagen Type I; Creatinine; Disease Progression; Female; Fluorescent Antibody Technique; Imatinib Mesylate; Piperazines; Protein Kinase Inhibitors; Proteinuria; Pyrimidines; Rats; Rats, Inbred WKY; Real-Time Polymerase Chain Reaction; Renal Insufficiency, Chronic; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Time Factors; Transforming Growth Factor beta

Atherosclerotic renal artery stenosis (ARAS) reduces renal blood flow and is a potential cause of chronic kidney injury, yet little is known regarding inflammatory pathways in this disorder in human participants. This study aimed to examine the hypothesis that reduced renal blood flow (RBF) in ARAS would be associated with tissue TGF-β activation and inflammatory cell accumulation.. This cross-sectional study of ARAS of varying severity compared transjugular biopsy specimens in patients with ARAS (n=12, recruited between 2008 and 2012) with tissue from healthy kidney donors (n=15) and nephrectomy specimens from individuals with total vascular occlusion (n=65). ARAS patients were studied under controlled conditions to measure RBF by multidetector computed tomography and tissue oxygenation by blood oxygen level-dependent magnetic resonance imaging.. Compared with the nonstenotic contralateral kidneys, RBF was reduced in poststenotic kidneys (242±149 versus 365+174 ml/min; P<0.01) as was single-kidney GFR (28±17 versus 41±19 ml/min; P<0.01), whereas cortical and medullary oxygenation were relatively preserved. Tissue TGF-β immunoreactivity was higher in ARAS patients compared with those with both normal kidneys and those with total occlusion (mean score 2.4±0.7 versus 1.5+1.1 in the nephrectomy group and versus 0±0 in donors; P<0.01). By contrast, the number of CD68+ macrophages was higher with greater disease severity (from 2.2±2.7 in normal to 22.4±18 cells/high-power field in nephrectomy samples; P<0.001).. The results of this study indicate robust stimulation of TGF-β associated with macrophage infiltration within the human kidney with vascular occlusive disease.

Topics: Aged; Atherosclerosis; Biopsy; Female; Fibrosis; Humans; Kidney Transplantation; Macrophages; Male; Middle Aged; Nephrectomy; Nephritis, Interstitial; Renal Artery Obstruction; Renal Circulation; Renal Insufficiency, Chronic; Tissue Donors; Transforming Growth Factor beta

Dietary sodium chloride (salt) has long been considered injurious to the kidney by promoting the development of glomerular and tubulointerstitial fibrosis. Endothelial cells throughout the vasculature and glomeruli respond to increased dietary salt intake with increased production of transforming growth factor-β (TGF-β) and nitric oxide. High-salt intake activates large-conductance, voltage- and calcium-activated potassium (BK(Ca)) channels in endothelial cells. Activation of BK(Ca) channels promotes signaling through proline-rich tyrosine kinase-2, cellular-sarcoma (c-Src), Akt (also known as protein kinase B), and mitogen-activated protein kinase pathways that lead to endothelial production of TGF-β and nitric oxide. TGF-β signaling is broadly accepted as a strong stimulator of renal fibrosis. The classic description of TGF-β signaling pathology in renal disease involves signaling through Smad proteins resulting in extracellular matrix deposition and fibrosis. Active TGF-β1 also causes fibrosis by inducing epithelial-mesenchymal transition and apoptosis. By enhancing TGF-β signaling, increased dietary salt intake leads to progressive renal failure from nephron loss and glomerular and tubulointerstitial fibrosis.

Topics: Animals; Endothelial Cells; Epithelial-Mesenchymal Transition; Fibrosis; Focal Adhesion Kinase 2; Humans; Kidney; Kidney Failure, Chronic; Large-Conductance Calcium-Activated Potassium Channels; Mice; Mitogen-Activated Protein Kinases; Nitric Oxide; Proto-Oncogene Proteins c-akt; Rats; Renal Insufficiency, Chronic; Signal Transduction; Smad Proteins; Sodium Chloride, Dietary; src-Family Kinases; Transforming Growth Factor beta; Transforming Growth Factor beta1

Increased risk of mortality in patients with CKD has been attributed to inflammation. However, the association between kidney function, albuminuria, and biomarkers of inflammation has not been examined in a large cohort of CKD patients.. This study measured the plasma levels of IL-1β, IL-1 receptor antagonist (IL-1RA), IL-6, TNF-α, TGF-β, high-sensitivity C-reactive protein (hs-CRP), fibrinogen, and serum albumin in 3939 participants enrolled in the Chronic Renal Insufficiency Cohort study between June 2003 and September 2008. An inflammation score was established based on plasma levels of IL-1β, IL-6, TNF-α, hs-CRP, and fibrinogen. Estimated GFR (eGFR) and serum cystatin C were used as measures of kidney function. Albuminuria was quantitated by urine albumin to creatinine ratio (UACR).. Plasma levels of IL-1β, IL-1RA, IL-6, TNF-α, hs-CRP, and fibrinogen were higher among participants with lower levels of eGFR. Inflammation score was higher among those with lower eGFR and higher UACR. In regression analysis adjusted for multiple covariates, eGFR, cystatin C, and UACR were strongly associated with fibrinogen, serum albumin, IL-6, and TNF-α. Each unit increase in eGFR, cystatin C, and UACR was associated with a -1.2% (95% confidence interval, -1.4, -1), 64.9% (56.8, 73.3) and 0.6% (0.4, 0.8) change in IL-6, respectively (P<0.001).. Biomarkers of inflammation were inversely associated with measures of kidney function and positively with albuminuria.

Topics: Aged; Albuminuria; Biomarkers; C-Reactive Protein; Cohort Studies; Confidence Intervals; Creatinine; Cystatin C; Cytokines; Female; Fibrinogen; Glomerular Filtration Rate; Humans; Inflammation; Interleukin 1 Receptor Antagonist Protein; Interleukin-1beta; Interleukin-6; Male; Middle Aged; Multivariate Analysis; Renal Insufficiency, Chronic; Serum Albumin; Statistics, Nonparametric; Transforming Growth Factor beta; Tumor Necrosis Factor-alpha

Hypertension and additional non-traditional risk factors can damage the kidney directly and by promoting atherogenesis. Evidence indicates that increased oxidative stress and inflammation may mediate a large part of the effects of risk factors on the kidney. We hypothesized that in hypertensive patients (HT), oxidative stress, measured as 8-ISO-prostaglandin F2alpha (8-ISO-PGF2alpha), should raise paralleling decreasing renal function and should correlate with estimated glomerular filtration rate (eGFR).. In 626 HT with renal function ranging from stages 1 to 5 and 100 healthy controls, plasma levels of 8-ISO-PGF2alpha, high-sensitivity C-reactive protein (CRP), transforming growth factor-beta (TGF-beta) and endothelin-1 (ET-1) were measured. GFR was estimated by the Modification of Diet in Renal Disease study equation.. When HT were stratified according to renal function stages, 8-ISO-PGF2alpha, CRP, TGF-beta and ET-1 increased progressively and significantly with decreasing eGFR. The multiple regression analysis, considering eGFR as a dependent variable, showed that 8-ISO-PGF2alpha (beta = -0.361, P < 0.000001), ET-1 (beta = -0.197, P < 0.0001) and TGF-beta (beta = -0.170, P < 0.0004) correlated independently with eGFR. All biomarkers were good predictors of eGFR <60 ml/min/1.73 m(2) [receiver-operator-curve (ROC) areas]. ET-1 was shown to be the best predictor with a ROC area = 0.938; with a threshold of 4 pg/ml, 91% sensitivity and 85% specificity were observed, whereas 8-ISO had a ROC area = 0.931, and for a threshold of 329 pg/ml, sensitivity and specificity were 89%, respectively. In contrast, CRP showed the lower predictive value with a ROC area = 0.917; with a threshold of 2.52 mg/l, an 87% sensitivity and an 83% specificity were obtained.. Our findings are a clear-cut demonstration of a strong and negative correlation of both oxidative stress and ET-1 with renal function stages in HT. ET-1 and 8-isoprostane are predictive of eGFR.

Topics: Adult; Aged; Atherosclerosis; C-Reactive Protein; Case-Control Studies; Dinoprost; Endothelin-1; Female; Glomerular Filtration Rate; Humans; Hypertension; Kidney; Male; Middle Aged; Oxidative Stress; Renal Insufficiency, Chronic; Risk Factors; Transforming Growth Factor beta

Scavenger receptors play a central role in atherosclerosis by processing oxidized lipoproteins and mediating their cellular effects. Recent studies suggested that the atherogenic state correlates with progression of chronic kidney disease (CKD); therefore, scavenger receptors are candidate mediators of renal fibrogenesis. Here, we investigated the role of CD36, a class B scavenger receptor, in a hypercholesterolemic model of CKD. We placed CD36-deficient mice and wild-type male mice on a high-fat Western diet for 7 to 8 wk and then performed either sham or unilateral ureteral obstruction surgery. CD36-deficient mice developed significantly less fibrosis compared with wild-type mice at days 3, 7, and 14 after obstruction. Compared with wild-type mice, CD36-deficient mice had significantly more interstitial macrophages at 7 d but not at 14 d. CD36-deficient mice exhibited reduced levels of activated NF-kappaB and oxidative stress (assessed by measuring fatty acid-derived hydroxyoctadecadienoic acid and protein carbonyl content) and decreased accumulation of interstitial myofibroblasts compared with wild-type mice. These data suggest that CD36 is a key modulator of proinflammatory and oxidative pathways that promote fibrogenesis in CKD.

Topics: Animals; CD36 Antigens; Chemokine CXCL10; Chemokines; Fibroblasts; Gene Expression; Hypercholesterolemia; Inflammation; Kidney; Lipoproteins; Macrophages; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; NF-kappa B; Oxidation-Reduction; Oxidative Stress; Renal Insufficiency, Chronic; RNA, Messenger; Transforming Growth Factor beta

Significant reduction of renal mass initiates a series of hemodynamic and nonhemodynamic events which lead to proteinuria, glomerulosclerosis, tubulointerstitial injury, and end-stage renal failure. Lipid mediators derived from fatty acids participate in regulation of renal hemodynamic and nonhemodynamic processes that influence progression of renal disease. Composition of cellular fatty acids and hence related signaling responses are influenced by their dietary contents. Consumption of omega-3 fatty acids (O-3FA) has proven effective in mitigating atherosclerosis. We tested the hypothesis that O-3FA supplementation may retard progression and attenuate upregulation of pathways involved in oxidative stress, inflammation, and fibrosis in rats with renal mass reduction. Sprague-Dawley rats were subjected to 5/6 nephrectomy [chronic renal failure (CRF)] and randomly assigned to the untreated and O-3FA-treated (0.3 g.kg(-1).day(-1) by gastric gavage for 12 wk) groups. Sham-operated rats served as controls. The untreated CRF rats exhibited proteinuria, hypertension, azotemia, upregulations of renal tissue NAD(P)H oxidase, MCP-1, COX-2, PAI-1, TGF-beta, Smad2, alpha-smooth muscle actin, fibronectin, and hepatocyte growth factor, activation of ERK1/2 and NF-kappaB, downregulation of Smad7, intense mononuclear leukocyte infiltration, tubulointerstitial fibrosis, and glomerulosclerosis. O-3FA supplementation significantly lowered COX-2, NAD(P)H oxidase (NOX-4, gp91(phox), p47(phox), p22(phox)), PAI-1, TGF-beta, connective tissue growth factor, alpha-smooth muscle actin, fibronectin, Smad2, and MCP-1, raised Smad7, and attenuated ERK1/2 and NF-kappaB activation, tubulointerstitial fibrosis, and inflammation. Thus, long-term O-3FA supplementation can reduce or reverse upregulation of prooxidant, proinflammatory, and profibrotic pathways and attenuate tubulointerstitial fibrosis in the remnant kidney.

Topics: Actins; Animals; Chemokine CCL2; Connective Tissue Growth Factor; Cyclooxygenase 2; Dietary Supplements; Extracellular Signal-Regulated MAP Kinases; Fatty Acids, Omega-3; Fibronectins; Fibrosis; Hepatocyte Growth Factor; Inflammation; Kidney; Male; NADPH Oxidases; Nephritis; NF-kappa B; Oxidative Stress; Plasminogen Activator Inhibitor 1; Rats; Rats, Sprague-Dawley; Renal Insufficiency, Chronic; Smad2 Protein; Smad7 Protein; Transforming Growth Factor beta

We have shown that renal injury and chronic kidney disease (CKD) directly inhibit skeletal anabolism, and that stimulation of bone formation decreases the serum phosphate. Most recently, these observations were rediscovered in low-density lipoprotein receptor null mice fed high-fat/cholesterol diets, a model of the metabolic syndrome (hypertension, obesity, dyslipidemia, and insulin resistance). We had demonstrated that these mice have vascular calcification (VC) of both the intimal atherosclerotic type and medial type. We have shown that VC is worsened by CKD and ameliorated by bone morphogenetic protein -7 (BMP-7). The finding that high-fat-fed low-density lipoprotein receptor null animals without CKD have hyperphosphatemia led us to examine the skeletons of these mice. We found significant reductions in bone formation rates, associated with increased VC and superimposing CKD results in the adynamic bone disorder (ABD), while VC was worsened and hyperphosphatemia persisted. A pathological link between abnormal bone mineralization and VC through the serum phosphorus was demonstrated by the partial effectiveness of directly reducing the serum phosphate by a phosphate binder that had no skeletal action. BMP-7 treatment corrected the ABD and corrected hyperphosphatemia, compatible with BMP-7-driven stimulation of skeletal phosphate deposition reducing plasma phosphate and thereby removing a major stimulus to VC. Thus, in the metabolic syndrome with CKD, a reduction in bone-forming potential of osteogenic cells leads to ABD producing hyperphosphatemia and VC, processes ameliorated by the skeletal anabolic agent BMP-7, in part through increased bone formation and skeletal deposition of phosphate, and in part through direct actions on vascular smooth muscle cells. We have demonstrated that the processes leading to vascular calcification begin with even mild levels of renal injury before demonstrable hyperphosphatemia, and they are preventable and treatable. Therefore, early intervention in CKD is warranted and may affect mortality of the disease.

Topics: Animals; Aorta, Thoracic; Bone Diseases; Bone Morphogenetic Protein 7; Bone Morphogenetic Proteins; Calcinosis; Calcium; Calcium Carbonate; Chronic Disease; Chronic Kidney Disease-Mineral and Bone Disorder; Dietary Fats; Disease Progression; Female; Hyperparathyroidism; Kidney Diseases; Male; Mice; Mice, Inbred C57BL; Osteoblasts; Osteogenesis; Phosphates; Renal Insufficiency, Chronic; Transforming Growth Factor beta