tretinoin and Diabetic-Nephropathies

The terminally differentiated podocyte, also called glomerular visceral epithelial cell, are highly specialized cells. They function as a critical size and charge barrier to prevent proteinuria. Podocytes are injured in diabetic and non-diabetic renal diseases. The clinical signature of podocyte injury is proteinuria, with or without loss of renal function owing to glomerulosclerosis. There is an exciting and expanding literature showing that hereditary, congenital, or acquired abnormalities in the molecular anatomy of podocytes leads to proteinuria, and at times, glomerulosclerosis. The change in podocyte shape, called effacement, is not simply a passive process following injury, but is owing to a complex interplay of proteins that comprise the molecular anatomy of the different protein domains of podocytes. These will be discussed in this review. Recent studies have also highlighted that a reduction in podocyte number directly causes proteinuria and glomerulosclerosis. This is owing to several factors, including the relative inability for these cells to proliferate, detachment, and apoptosis. The mechanisms of these events are being elucidated, and are discussed in this review. It is the hope that by delineating the events following injury to podocytes, therapies might be developed to reduce the burden of proteinuric renal diseases.

Topics: Adrenal Cortex Hormones; Angiotensin II Type 1 Receptor Blockers; Apoptosis; Cell Adhesion; Cell Count; Cell Cycle; Cell Proliferation; Cytoskeleton; Diabetic Nephropathies; DNA Damage; Endothelium; Glomerular Basement Membrane; Glomerulosclerosis, Focal Segmental; Humans; Hypertrophy; Podocytes; Proteinuria; Tretinoin

The present study aims to formulate all-trans retinoic acid (ATRA) loaded chitosan/tripolyphosphate lipid hybrid nanoparticles (CTLHNs) for enhancing its solubility and oral delivery. This is to improve ATRA therapeutic effect on diabetic nephropathy (DN). CTLHNs were prepared by o/w homogenization, employing stearic acid, to form lipid nanoparticles coated with chitosan that is stabilized against acidic pH via sodium tripolyphosphate crosslinking. Chitosan coated (F7) and naked lipid nanoparticles (F6) were also prepared for comparison with CTLHNs. In vitro characterization for the prepared formulations was performed comprising entrapment efficiency, particle size, zeta potential, transmission electron microscopy, FT-IR spectroscopy and x-ray diffraction. Stability of chitosan coat in GI fluid revealed that CTLHNs were more stable than F7. In vitro release indicated an enhanced release of ATRA from the developed formulations. In vitro mucoadhesion study proved a notable mucoadhesive property for CTLHNs. In DN rat model, serum levels of creatinine and urea were elevated, over expression of tumor necrosis factor alpha (TNF-α), granulocyte macrophage colony-stimulating factor (GM-CSF), vascular endothelial growth factor (VEGF) and intercellular adhesion molecule-1 (ICAM-1) were observed. In addition, adenosine monophosphate activated protein kinase (AMPK) and liver kinase B1 (LKB1) expressions were decreased in DN rats. Treatment with free ATRA and the selected formulations led to a significant amelioration of DN by reducing of creatinine, urea, TNF-α, ICAM-1, GM-CSF, VEGF levels as well as elevating AMPK and LKB1 levels. The order of activity was: CTLHNs > F7 > F6 > free ATRA, as proved by histopathological examination.

Topics: Animals; Chitosan; Diabetes Mellitus; Diabetic Nephropathies; Drug Carriers; Lipids; Nanoparticles; Particle Size; Polyphosphates; Rats; Spectroscopy, Fourier Transform Infrared; Tretinoin; Vascular Endothelial Growth Factor A

Diabetic nephropathy (DN) involves damage associated to hyperglycemia and oxidative stress. Renal fibrosis is a major pathologic feature of DN. The aim of this study was to evaluate anti-fibrogenic and renoprotective effects of all-trans retinoic acid (ATRA) in isolated glomeruli and proximal tubules of diabetic rats. Diabetes was induced by single injection of streptozotocin (STZ, 60 mg/Kg). ATRA (1 mg/Kg) was administered daily by gavage, from days 3-21 after STZ injection. ATRA attenuated kidney injury through the reduction of proteinuria, renal hypertrophy, increase in natriuresis, as well as early markers of damage such as β2-microglobulin, kidney injury molecule-1 (KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL). The following parameters increased: macrophage infiltration, localization of alpha-smooth muscle actin (αSMA)-positive cells in renal tissue, and pro-fibrotic proteins such as transforming growth factor-β (TGF-β1), laminin beta 1 (LAM-β1), and collagens IV and I. Remarkably, ATRA treatment ameliorated these alterations and attenuated expression and nuclear translocation of Smad3, with increment of glomerular and tubular Smad7. The diabetic condition decreased expression of retinoic acid receptor alpha (RAR-α) through phosphorylation in serine residues mediated by the activation of c-Jun N-terminal kinase (JNK). ATRA administration restored the expression of RAR-α and inhibited direct interactions of JNK/RAR-α. ATRA prevented fibrogenesis through down-regulation of TGF-β1/Smad3 signaling.

Topics: Actins; Animals; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Down-Regulation; Drug Administration Schedule; Gene Expression Regulation; Male; Oxidative Stress; Rats; Signal Transduction; Smad3 Protein; Streptozocin; Transforming Growth Factor beta1; Tretinoin

Diabetic nephropathy (DN) causes mesangial matrix expansion, which results in glomerulosclerosis and renal failure. Collagen IV (COL4) is a major component of the mesangial matrix that is positively regulated by bone morphogenetic protein 4 (BMP4)/suppressor of mothers against decapentaplegic (Smad1) signaling. Because previous studies showed that retinoids treatment had a beneficial effect on kidney disease, we investigated the therapeutic potential of retinoids in DN, focusing especially on the regulatory mechanism of BMP4. Diabetes was induced with streptozotocin in 12-wk-old male Crl:CD1(ICR) mice, and, 1 mo later, we initiated intraperitoneal injection of all-trans retinoic acid (ATRA) three times weekly. Glomerular matrix expansion, which was associated with increased BMP4, phosphorylated Smad1, and COL4 expression, worsened in diabetic mice at 24 wk of age. ATRA administration alleviated DN and downregulated BMP4, phosopho-Smad1, and COL4. In cultured mouse mesangial cells, treatment with ATRA or a retinoic acid receptor-α (RARα) agonist significantly decreased BMP4 and COL4 expression. Genomic analysis suggested two putative retinoic acid response elements (RAREs) for the mouse Bmp4 gene. Chromatin immunoprecipitation analysis and reporter assays indicated a putative RARE of the Bmp4 gene, located 11,488-11,501 bp upstream of exon 1A and bound to RARα and retinoid X receptor (RXR), which suppressed BMP4 expression after ATRA addition. ATRA suppressed BMP4 via binding of a RARα/RXR heterodimer to a unique RARE, alleviating glomerular matrix expansion in diabetic mice. These findings provide a novel regulatory mechanism for treatment of DN.

Topics: Animals; Bone Morphogenetic Protein 4; Cells, Cultured; Collagen Type IV; Diabetic Nephropathies; Mesangial Cells; Mice; Response Elements; Retinoic Acid Receptor alpha; Retinoid X Receptors; Smad1 Protein; Tretinoin

Diabetic nephropathy (DN) is the leading cause of renal failure worldwide and its complications have become a public health problem. Inflammation, oxidative stress and fibrosis play central roles in the progression of DN that lead to renal failure. Potential deleterious effect of inflammation in early evolution of DN is not fully disclosed. Therefore, it is relevant to explore therapies that might modulate this process in order to reduce DN progression. We explored the beneficial effect of all-trans retinoic acid (ATRA) in early inflammation in glomeruli, proximal and distal tubules in streptozotocin (STZ)-induced diabetes. ATRA was administered (1 mg/kg daily by gavage) on days 3 to 21 after STZ administration. It was found that 21 days after STZ injection, diabetic rats exhibited proteinuria, increased natriuresis and loss of body weight. Besides, diabetes induced an increase in interleukins [IL-1β, IL-1α, IL-16, IL-13, IL-2; tumor necrosis factor alpha (TNF-α)] and transforming growth factor-beta 1 (TGF-β1), chemokines (CCL2, CCL20, CXCL5 and CXCL7), adhesion molecules (ICAM-1 and L-selectin) and growth factors (GM-CSF, VEGF, PDGF) in glomeruli and proximal tubules, whereas ATRA treatment remarkably ameliorated these alterations. To further explore the mechanisms through which ATRA decreased inflammatory response, the NF-κB/p65 signaling mediated by TLR4 was studied. We found that ATRA administration attenuates the TLR4/NF-κB inflammatory signaling and prevents NF-κB nuclear translocation in glomeruli and proximal tubules.

Topics: Animals; Cell Adhesion Molecules; Chemokines; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Female; Inflammation; Intercellular Signaling Peptides and Proteins; Interleukins; Kidney Glomerulus; Kidney Tubules; NF-kappa B; Rats; Rats, Wistar; Toll-Like Receptor 4; Tretinoin

The aim of this study was to examine the effects of all-trans retinoic acid (ATRA) on diabetic nephropathy.. We measured amounts of urinary albumin excretion (UAE) after administrating ATRA to Otsuka Long-Evans Tokushima Fatty (OLETF) rats. In order to understand the mechanism of action for ATRA, we administrated ATRA to examine its inhibitory action on the production of transforming growth factor-β₁ (TGF-β₁), protein kinase C (PKC), and reactive oxidative stress (ROS) in cultured rat mesangial cells (RMCs).. After 16 weeks of treatment, UAE was lower in the ATRA-treated OLETF rats than in the non-treated OLETF rats (0.07±0.03 mg/mgCr vs. 0.17±0.15 mg/mgCr, p<0.01). After incubation of RMCs in media containing 30 or 5 mM of glucose, treatment with ATRA showed time- and dose-dependent decreases in TGF-β₁ levels and ROS. Moreover, ATRA treatment showed a dose-dependent decrease in PKC expression.. ATRA treatment suppressed UAE and TGF-β₁ synthesis, which was mediated by significant reductions in PKC activity and ROS production. Our results suggest that ATRA has a potential therapeutic role for diabetic nephropathy.

Topics: Animals; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Mesangial Cells; Oxidative Stress; Rats; Rats, Inbred OLETF; Reactive Oxygen Species; Transforming Growth Factor beta1; Tretinoin

Topics: Angiotensin II; Angiotensin Receptor Antagonists; Angiotensin-Converting Enzyme Inhibitors; Chi-Square Distribution; Diabetes Mellitus; Diabetic Nephropathies; Disease Progression; Follow-Up Studies; Humans; Kidney Failure, Chronic; Proteinuria; Randomized Controlled Trials as Topic; Risk Factors; Time Factors; Tretinoin

Although the pathogenetic mechanism of diabetic nephropathy has not been elucidated, an inflammatory mechanism has been suggested to contribute to its progression. Monocyte chemoattractant peptide (MCP)-1 attracts macrophages and T cells, and ultimately injures renal tissue. In early diabetic nephropathy, urinary excretion of MCP-1 was elevated, and increased as renal damage became more severe. Podocytes are expected to have an inflammatory role in diabetic nephropathy, as the surface expression of chemokine receptors such as CCR and CXCR on these cells has been recently reported. Although retinoid (retinal), a known anti-inflammatory agent, has been reported to be beneficial in some experimental models of renal disease, it has not been determined to prevent disease progression in diabetic nephropathy. We investigated the effects of all-trans retinoic acid on the production of MCP-1 under high glucose conditions in cultured mouse podocytes. We also evaluated whether all-trans retinoic acid inhibits inflammatory changes and improves renal function during the early stages of diabetic nephropathy in streptozotocin-induced diabetic rats. In cultured podocytes, high glucose stimuli rapidly upregulated the MCP-1 mRNA transcript and protein release. Treatment with retinoic acid tended to suppress the MCP-1 gene transcript, and significantly inhibited MCP-1 protein synthesis induced by high glucose stimulation. Urinary protein excretion and the urinary albumin : creatinine ratio (ACR) were significantly higher in diabetic rats 4 weeks after the induction of diabetes mellitus compared with control rats, and retinoic acid treatment markedly decreased both proteinuria and urinary ACR (proteinuria: 1.25+/-0.69 vs 0.78+/-0.72 mg/mgCr, P=0.056; urinary ACR: 0.47+/-0.25 vs 0.21+/-0.06 mg/mgCr, P=0.088). Urinary excretion of MCP-1 was rapidly increased 2 days after induction of diabetes mellitus in diabetic rats, and further increased until rats were 4 weeks of age, compared with control rats. Retinoic acid treatment resulted in 30% reduction of the urinary level of MCP-1 compared with vehicle-treated diabetic rats (119.3+/-74.2 vs 78.1+/-62.7 pg/mgCr, P=0.078). Immunohistochemistry revealed a significant increase in staining for MCP-1 and anti-monocyte/macrophage (ED-1) protein in the diabetic kidney, and retinoic acid treatment significantly suppressed intrarenal MCP-1 and ED-1 protein synthesis. In conclusion, podocytes are involved in the inflammatory reaction under

Topics: Animals; Cell Line; Chemokine CCL2; Creatine; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Glucose; Immunohistochemistry; Male; Mice; Proteinuria; Rats; Rats, Sprague-Dawley; RNA, Messenger; Streptozocin; Tretinoin