transforming-growth-factor-beta and Kidney-Tubular-Necrosis--Acute

Chronic renal failure is the consequence of progressive glomerulosclerosis and tubulo-interstitial fibrosis. The initiating hallmark of nephrosclerosis represents nephronal hypertrophy, due to an accumulation of proteins in the glomeruli and tubulointerstitium. From experimental and clinical investigations the conclusion can be drawn that the disturbed intrarenal protein balance with the consequent nephronal hypertrophy is at least partly the result of reduced protein degradation. Potential factors involved in impaired renal proteinase activities are cytokines like transforming growth factor beta 1 (TGF-beta 1), angiotensin II and advanced glycation endproducts (AGEs).. Nephrosclerosis as the common histological endpoint of chronic renal insufficiency is the result of an interaction between many pathogenetic factors. Its growing understanding implies the possibility of new therapeutic options to retard the progressive course of chronic renal failure.

Topics: Angiotensin II; Diabetic Nephropathies; Glycation End Products, Advanced; Humans; Kidney; Kidney Failure, Chronic; Kidney Tubular Necrosis, Acute; Proteins; Transforming Growth Factor beta

Cyclosporine A (CsA) is a potent immunosuppressive drug that inhibits the transcription of several proinflammatory cytokines including interleukin-2. In contrast, CsA stimulates transcription of the pleuripotent cytokine, transforming growth factor-beta (TGF beta). Since the effect of CsA in transplant recipients is unpredictable, we examined whether tissue levels of TGF beta protein in renal allografts correlate with in vivo CsA responsiveness. Intra-allograft TGF beta protein content was assessed in renal biopsies by immunohistochemical means using the mouse anti-TGF beta monoclonal antibody (Mab), 1D11. We studied 68 specimens: 21 with acute CsA toxicity (ACT), 11 with acute tubular necrosis (ATN) and 36 with acute cellular rejection (ACR). Intensity of TGF beta immunostaining was evaluated in a blinded fashion using a scale from 0 to 3+. In biopsies with histological evidence of CsA toxicity, 77% demonstrated intense (2 to 3+) TGF beta immunostaining. TGF beta protein was detected in both proximal and distal tubules but was either absent or present in low levels within glomeruli and interstitium. In contrast, only one of the 11 biopsies with ATN had minimal staining (1+) for TGF beta. The remaining 10 biopsies with ATN were negative for TGF beta immunostaining. In biopsies with ACR, the levels of renal TGF beta were more variable with 36% showing intense (2 to 3+) staining and 64% having minimal or no (0 to 1+) tubular TGF beta. Within the first 18 months post-transplantation, patients with intense TGF beta staining and ACR underwent an average of 4.1 +/- 1.8 allograft biopsies and suffered 33% graft losses. During the same period of time, the patients with ACR and absent or low (0 to 1+) TGF beta levels underwent only 2.1 +/- 1.2 biopsies, maintained better late renal function and suffered 4% graft losses. In conclusion, we demonstrate that TGF beta protein levels in renal allografts correlate with CsA effect and differentiate ACT from ATN. In CsA treated patients who develop ACR, TGF beta levels predict the subsequent clinical course and graft function. Therefore, evaluating tissue levels of TGF beta may offer unique diagnostic and prognostic benefits in the care of patients receiving CsA based immunosuppression.

Topics: Adult; Animals; Cyclosporine; Female; Graft Rejection; Humans; Immunoenzyme Techniques; Immunohistochemistry; Immunosuppressive Agents; Kidney; Kidney Transplantation; Kidney Tubular Necrosis, Acute; Kidney Tubules; Male; Mice; Transforming Growth Factor beta; Treatment Outcome

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

Renal perfusion pressure was servo-controlled chronically in rats to quantify the relative contribution of elevated arterial pressure versus angiotensin II (Ang II) on the induction of renal injury in Ang II-induced hypertension. Sprague-Dawley rats fed a 4% salt diet were administered Ang II for 14 days (25 ng/kg per minute IV; saline only for sham rats), and the renal perfusion pressure to the left kidney was continuously servo-controlled to maintain a normal pressure in that kidney throughout the period of hypertension. An aortic occluder was implanted around the aorta between the two renal arteries and carotid and femoral arterial pressure were measured continuously throughout the experiment to determine uncontrolled and controlled renal perfusion pressure, respectively. Renal perfusion pressure of uncontrolled, controlled, and sham kidneys over the period of Ang II or saline infusion averaged 152.6+/-7.0, 117.4+/-3.5, and 110.7+/-2.2 mm Hg, respectively. The high-pressure uncontrolled kidneys exhibited tubular necrosis and interstitial fibrosis, especially prominent in the outer medullary region. Regional glomerular sclerosis and interlobular artery injury were also pronounced. Controlled kidneys were significantly protected from interlobular artery injury, juxtamedullary glomeruli injury, tubular necrosis, and interstitial fibrosis as determined by comparing the level of injury. Glomerular injury was not prevented in the outer cortex. Transforming growth factor (TGF)-beta and active NF-kappaB proteins determined by immunohistochemistry were colocalized in the uncontrolled kidney in regions of interstitial fibrosis. We conclude that the preferential juxtamedullary injury found in Ang II hypertension is largely induced by pressure and is probably mediated through the TGF-beta and NF-kappaB pathway.

Topics: Angiotensin II; Animals; Aortic Valve Stenosis; Blood Pressure; Carotid Arteries; Femoral Artery; Fibrosis; Hypertension; Kidney; Kidney Tubular Necrosis, Acute; Male; NF-kappa B; Pressure; Rats; Rats, Sprague-Dawley; Renal Circulation; Sodium Chloride, Dietary; Transforming Growth Factor beta

Abnormalities of renal function with long-term implications can persist after acute tubular necrosis (ATN), probably because of permanent loss of nephrons. Residual areas of fibrosis are also observed in the renal cortex post-ATN. In this study, we investigate the interstitial alterations post-ATN using histological and immunohistochemical methods.. We studied 11 patients with ATN of different etiologies and 19 patients with ATN post-renal transplantation. Eleven patients with ATN post-renal transplantation and one with ATN not related to renal transplantation were submitted to more than one biopsy because of delayed renal function recovery. The immunohistochemical studies were performed using alpha-smooth muscle-actin (alpha-SM-actin), endothelin, nuclear factor-kappaB (NF-kappaB), Jun-N-terminal kinase (p-JNK) and fibronectin antibodies. We also analyzed the urinary content of transforming growth factor-beta (TGF-beta) during the acute phase of ATN.. The immunohistochemical studies showed increased alpha-SM-actin, fibronectin, endothelin, p-JNK and NF-kappaB staining in the tubulointerstitium area from the renal cortex of all patients when compared with controls (p < 0.001), and these increase persisted in the patients submitted to sequential biopsies. One of the patients with ATN without renal transplant and six patients with ATN post-renal transplant developed chronic renal failure. There was a significant increase of TGF-beta excretion in the urine of patients with acute renal failure (p < 0.01) compared with control.. Our data show that the enhancement of renal TGF-beta production and the persistent increase of myofibroblasts, fibronectin, endothelin, p-JNK and NF-kappaB in renal cortex tubulointerstitium post-ATN may explain the impaired recovery of renal function observed in patients post-ATN frequently observed in patients with ATN post-renal transplant.

Topics: Actins; Adolescent; Adult; Endothelins; Female; Humans; Immunohistochemistry; JNK Mitogen-Activated Protein Kinases; Kidney Cortex; Kidney Transplantation; Kidney Tubular Necrosis, Acute; Male; Middle Aged; Mitogen-Activated Protein Kinases; NF-kappa B; Transforming Growth Factor beta

Pathologic fibrosis is a key feature of progressive renal disease that correlates closely with kidney dysfunction and in which the prosclerotic growth factor TGF-beta has been consistently implicated. Tranilast (n-[3,4-dimethoxycinnamoyl] anthranilic acid), an antifibrotic agent that is used to treat hypertrophic scars and scleroderma, has also been shown to inhibit TGF-beta-induced extracellular matrix synthesis in a range of cell types, including those of renal origin. Therefore, the effects of tranilast on kidney fibrosis and dysfunction were examined in the subtotal nephrectomy model of progressive renal injury. Subtotal nephrectomy led to proteinuria and renal dysfunction in association with glomerulosclerosis, tubulointerstitial fibrosis, and macrophage accumulation. Despite persistent hypertension, treatment with tranilast led to a reduction in albuminuria (61.7 (x)/(/) 1.2 versus 20.5 (x)/(/) 1.3 mg/d; P < 0.01) and plasma creatinine (0.16 versus 0.08 mmol/L; P < 0.01) in subtotally nephrectomized rats. In addition, features suggestive of TGF-beta activation, including glomerulosclerosis, tubulointerstitial fibrosis, tubular atrophy, and macrophage accumulation, all were significantly attenuated by tranilast in association with evidence of reduced TGF-beta signaling in vivo. In the context of a recent pilot study in humans, the findings of the present report suggest that tranilast may provide a novel strategy for the treatment of progressive kidney disease characterized by fibrotic scarring.

Topics: Animals; Apoptosis; Base Sequence; Cell Proliferation; Disease Models, Animal; DNA, Complementary; Glomerulosclerosis, Focal Segmental; Immunohistochemistry; In Situ Nick-End Labeling; Kidney Tubular Necrosis, Acute; Male; Molecular Sequence Data; Nephrectomy; Organ Culture Techniques; ortho-Aminobenzoates; Probability; Random Allocation; Rats; Rats, Sprague-Dawley; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sensitivity and Specificity; Transforming Growth Factor beta

Chronic allograft nephropathy (CAN) remains a major problem in clinical transplantation. It has been associated with increased transforming growth factor (TGF-beta1). Our goal was to correlate CAN and levels of TGF-beta1 by using a novel competitive quantitative for reverse transcription-polymerase chain reaction-ELISA (RT-PCR-ELISA) assay.. We studied 12 transplantation patients (posttransplant time: 36.5+/-11.2 months, range (r): 13-52) with stable creatinine and blood pressure and varied proteinuria. A Kidney biopsy was performed in all patients. Six patients with acute tubular necrosis (ATN) immediately after transplantation were used as controls. Histopathological evaluation was based on Banff working classification criteria. We designed an heterologous RNA competitor (IC) for RT-PCR-ELISA, which co-amplified with the same primer as TGF-beta1. Products were viewed on 96-well plates labeled with probes for IC at the desired sequence.. Results were expressed as the number of TGF-beta1 copies/microg of total RNA. Six patients showed more than 1000 mg/24 hr proteinuria (2446+/-1421 mg/24 hr, r: 1200-5000) higher CAN Banff scores, and the other six presented <1,000 mg/24 hr (348+/-267 mg/24 hr, r: 114-800). This difference was significant (P=0.01). There were not significant differences in posttransplant time, creatinine, or blood pressure between groups. TGF-beta1 levels by RT-PCR-ELISA were statistically significant (6038+/-5317, r: 1239-12100 versus 177+/-119.7, r: 51-400, P=0.04). The control group showed levels of 228+/-111, r. 140-444, P=0.04) with significant difference only for the higher proteinuria group (P=0.03).. This study showed that those patients with elevated CAN scores and higher proteinuria levels had higher TGF-beta1 intragraft expression.

Topics: Adolescent; Adult; Base Sequence; Biomarkers; Biopsy, Needle; Blood Pressure; Creatinine; DNA Primers; Enzyme-Linked Immunosorbent Assay; Female; Humans; Kidney Transplantation; Kidney Tubular Necrosis, Acute; Living Donors; Male; Middle Aged; Molecular Sequence Data; Proteinuria; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Tissue Donors; Transcription, Genetic; Transforming Growth Factor beta

We noted previously that ischemic acute tubular necrosis (ATN) induces local expression of MHC products in renal epithelium. The present investigations were conducted to establish the role of IFN-gamma in the regulation of MHC antigen expression in ATN and to explore the changes in cytokine and growth factor expression induced by ischemic renal injury. We produced unilateral ischemic ATN in mice by clamping the left renal pedicle. MHC class I and II steady state mRNA induction was assessed by northern blot analysis, and MHC product was quantified by the extent of binding of radiolabeled monoclonals to tissue homogenates. The steady state mRNA levels for IFN-gamma, IL-2, IL-10, and granulocyte-macrophage CSF were assessed by reverse transcriptase polymerase chain reaction and the levels for transforming growth factor-beta 1 and prepro-epidermal growth factor (ppEGF) were assessed by Northern blot analysis. In the injured kidneys, steady state mRNA levels for IFN-gamma, IL-2, IL-10, granulocyte-macrophage CSF, and transforming growth factor beta-1 were increased, whereas ppEGF mRNA was markedly decreased. The MHC expression was inhibited by treatment of mice with an anti-IFN-gamma mAb (R4-6A2). Murine EGF, administered in an attempt to accelerate recovery, did not reduce the cytokine and MHC changes. These data indicate that ischemic injury, and possibly other forms of injury, triggers a complex circuit of proinflammatory cytokines. This "injury response" could be relevant to clinical renal transplants, where ATN is associated with poor graft outcome.

Topics: Animals; Antibodies, Monoclonal; Base Sequence; Cytokines; Disease Models, Animal; DNA, Complementary; Epidermal Growth Factor; Histocompatibility Antigens; Interferon-gamma; Ischemia; Kidney; Kidney Tubular Necrosis, Acute; Male; Mice; Mice, Inbred BALB C; Molecular Sequence Data; RNA, Messenger; Transforming Growth Factor beta