Sirolimus increases transforming growth factor-beta1 expression and potentiates chronic cyclosporine nephrotoxicity

BACKGROUND: Sirolimus (SRL) is increasingly being used to decrease cyclosporine (CsA) exposure. SRL is not known to be nephrotoxic and has a mechanism of action distinct from CsA. We investigated the effect of combining CsA and SRL on renal structure and function and on transforming growth factor-beta1 (TGF-beta1) and extracellular matrix (ECM) proteins in a model of chronic CsA nephrotoxicity. METHODS: Rats treated with vehicle, SRL 0.3 mg/kg/day, CsA 5 or 10 mg/kg/day, or CsA5+SRL were sacrificed at 7 or 28 days. Physiologic and histologic changes were studied in addition to TGF-beta1 mRNA and protein expressions, and mRNA expression of plasminogen activator inhibitor-1 (PAI-1) and ECM proteins biglycan and types I and IV collagen. RESULTS: While SRL alone did not alter renal function and structure, it potentiated the nephrotoxic actions of CsA when used in combination with low-dose CsA5 and resulted in significant changes similar to high-dose CsA10. In addition, SRL alone increased TGF-beta1 by 44% to 49% (P < 0.05 vs. VH). When used in combination with low-dose CsA5, SRL potentiated TGF-beta1 mRNA and protein by 121% and 176%, respectively (P < 0.05 vs. VH and CsA5), to levels achieved with high-dose CsA10. The expression of the ECM proteins followed that of TGF-beta1; a similar effect was observed with PAI-1, suggesting a decrease in ECM degradation. CONCLUSION: Because SRL augments nephrotoxicity, caution should be exercised when it is used in combination with CsA. More studies are needed to determine the long-term clinical impact of SRL on nephrotoxicity and allograft function.     

Synergistic effects of mycophenolate mofetil and losartan in a model of chronic cyclosporine nephropathy

BACKGROUND: Combined treatments of mycophenolate mofetil (MMF) and losartan (LSRT) have synergistic effects on various renal diseases through their hemodynamic and anti-inflammatory effects. This study investigated whether MMF treatment is effective in inhibiting inflammatory processes in chronic cyclosporine A (CsA) nephrotoxicity, and whether combined treatment using MMF and LSRT affords superior protection compared with the respective monotherapies. METHODS: Rats on a low-salt diet were given vehicle (VH group, olive oil, 1 mg/kg per day), CsA (15 mg/kg per day), CsA and LSRT (CsA+LSRT group, 100 mg/L per day), CsA and MMF (CsA+MMF group; 40 mg/kg per day), or CsA, LSRT and MMF (CsA+LSRT MMF group). Control groups received each drug without CsA treatment. Renal function, histologic parameters (arteriolopathy, tubulointerstitial fibrosis, and inflammatory cell infiltration), and mediators of CsA-induced nephrotoxicity (angiotensin-II, osteopontin, and transforming growth factor [TGF]-beta1) were studied. RESULTS: The CsA-treated rats showed decreased renal function and increased histologic parameters compared with the VH-treated rats. The CsA+MMF treatment significantly improved renal function and histopathologic parameters compared with the CsA group, and combined treatment with MMF and LSRT further improved those parameters compared with the CsA+LSRT and CsA+MMF groups. At a molecular level, increased expression of angiotensin II protein, osteopontin, and TGF-beta1 mRNAs in the CsA group were significantly decreased with MMF, and further decrease was observed with the combined treatment using MMF and LSRT. CONCLUSIONS: MMF treatment decreases CsA-induced nephrotoxicity, and combined treatment with LSRT has a synergistic effect in preventing chronic CsA nephrotoxicity.     

Effect of nitric oxide modulation on TGF-beta1 and matrix proteins in chronic cyclosporine nephrotoxicity

BACKGROUND: Chronic cyclosporine (CsA) nephrotoxicity is characterized by interstitial fibrosis and afferent arteriolar hyalinosis. L-arginine (L-Arg), the substrate for nitric oxide (NO) synthase and N-nitro-L-arginine-methyl ester (L-NAME), the NO synthase inhibitor, were shown to modulate acute CsA nephrotoxicity. However, the mechanism of fibrosis in chronic CsA nephrotoxicity remains unclear. Thus, we examined the effect of NO modulation on fibrosis and the expression of transforming growth factor-beta1 (TGF-beta1) and matrix proteins in chronic CsA nephrotoxicity. METHODS: Rats were administered CsA (7.5 mg/kg), CsA + L-Arg (1.7 g/kg), CsA + L-NAME (3.5 mg/kg), vehicle (VH), VH + L-Arg, and VH + L-NAME, and were sacrificed at 7 or 28 days. NO production, physiologic parameters, and histology were studied in addition to the mRNA expression of TGF-beta1, plasminogen activator inhibitor-1 (PAI-1) and the matrix proteins biglycan and collagens type I and IV by Northern and the protein expression of PAI-1 and fibronectin by enzyme-linked immunosorbent assay. RESULTS: While L-NAME strikingly reduced NO biosynthesis and worsened the glomerular filtration rate and CsA-induced fibrosis, L-Arg had the opposite beneficial effect. In addition, the CsA-induced up-regulated expression of TGF-beta1, PAI-1, and the matrix proteins biglycan, fibronectin, and collagen I was significantly increased with L-NAME and strikingly improved with L-Arg. Collagen IV expression was not affected. Also, NO modulation did not affect VH-treated rats. CONCLUSIONS: Chronic CsA nephrotoxicity can be aggravated by NO blockade and ameliorated by NO enhancement, suggesting that NO maintains a protective function. NO modulation was associated with a change in TGF-beta1 expression, which, in turn, was associated with alterations in matrix deposition and matrix degradation through its effect on PAI-1.     

Pirfenidone Treatment Decreases Transforming Growth Factor-β1 and Matrix Proteins and Ameliorates Fibrosis in Chronic Cyclosporine Nephrotoxicity

Chronic cyclosporine (CsA) nephrotoxicity is characterized by tubulointerstitial fibrosis. Pirfenidone (PFD) is a novel antifibrotic compound that was shown to prevent and even reverse fibrosis. The mechanism of action of PFD is unclear but involves inhibition of transforming growth factor-beta (TGF-beta). Salt-depleted rats were administered CsA, CsA + PFD, vehicle (VH) or VH + PFD and sacrificed at 28days. Physiologic and histologic changes were studied in addition to TGF-beta1, plasminogen activator inhibitor-1 (PAI-1) and biglycan mRNA expressions by Northern blot. TGF-beta1 immunohistochemistry was also performed. Treatment with PFD ameliorated CsA-induced fibrosis by about 50% (p < 0.05). CsA-induced decrease in creatinine clearance improved with PFD but the difference was not significant. TGF-beta1, PAI-1 and biglycan mRNA expressions increased with CsA (p < 0.05 vs. VH) but strikingly improved with PFD treatment (p < 0.05 vs. CsA), which brought the levels down to VH levels. PFD treatment also decreased TGF-beta1 protein expression by 80%. These results demonstrate that PFD can attenuate renal fibrosis in this model. PFD was associated with a decrease in TGF-beta1 expression, which, in turn, was associated with a decrease in matrix deposition. These experiments suggest that PFD can be clinically useful for preventing chronic CsA nephrotoxicity and may prove to be helpful in other progressive renal diseases.     

Effect of cyclosporine and sirolimus on the expression of connective tissue growth factor in rat experimental chronic nephrotoxicity

BACKGROUND/AIMS: Connective tissue growth factor (CTGF) is a pro-fibrotic growth factor that acts downstream of transforming growth factor (TGF)-beta. However, CTGF regulation remains unknown. We tried to determine the effect of two commonly used immunosuppressants, cyclosporine (CsA) and sirolimus (SRL), on CTGF expression in a model of chronic nephrotoxicity. METHODS: Adult Sprague-Dawley rats kept on a low-salt diet were treated daily for 4 weeks with vehicle (VH), SRL (0.3 mg/kg), CsA5 (5 mg/kg), CsA10 (10 mg/kg) or both CsA5 and SRL. CTGF and TGF-beta1 expressions were evaluated by Northern blot. Functional and histologic parameters in addition to number of apoptotic cells were determined. RESULTS: At 28 days, both CsA doses were capable of inhibiting CTGF mRNA expression to levels similar to control. On the other hand, SRL increased CTGF expression by 3.5-fold. However, addition of CsA to SRL completely reversed that trend and returned levels to control. The results were different for TGF-beta1, which was increased by both CsA and SRL and to a greater extent by the drug combination. CONCLUSION: Unlike TGF-beta, CTGF does not seem to play an important role in CsA-induced chronic nephrotoxicity. In addition, calcineurin-dependent pathways are likely involved in CTGF regulation.     

The effects of different immunosuppressants on chronic allograft nephropathy by affecting the transforming growth factor-beta and Smads signal pathways

OBJECTIVE: This study investigated the effects of various immunosuppressants on chronic allograft nephropathy (CAN) by affecting transforming growth factor-beta (TGF-beta) and Smads signal pathway. METHODS: Vascular smooth muscle cells (VMSC) from rat aorta were incubated for 6 or 12 hours with various immunosuppressants. Cyclosporine (CsA) (3 microg/mL), FK506 (1 microg/mL), mycophenolate mofetil (MMF) (0.3 microg/mL), rapamycine (Rapa) (10 microg/mL), CsA (1 microg/mL/MMF 0.3 microg/mL). We used the Sprague-Dawley Wistar rat accelerated kidney sclerosis model. Before transplantation, the kidney was preserved 1 hour in 0 degrees C to 4 degrees C heparin sodium chloride solution to reinforce the cold ischemia injury. The rats were divided into eight groups (each group n = 8): group A, pseudo-OP; group B, isotransplantation; group C, CsA 6 mg/kg . d; group D, FK506 0.15 mg/kg . d; group E, MMF 20 mg/kg . d; group F, Rapa 0.8 mg/kg. d; group G, CsA 3 mg/kg . d + MMF 20 mg/kg . d. The serum creatinine levels and pathological changes, according to the Banff scheme, were observed at 2, 4, 6, 8 and 12 weeks posttransplantation. Immunohistochemistry and quantitative fluorescence polymerase chain reactions were used to end localize and quantitate the expression of TGF-beta1 and Smad 2, 3, 7 in VMSC and in the transplanted kidney. RESULTS: CsA and FK506 stimulated gene expression and protein production of TGF-beta1, smad2, and smad3, but inhibited expression of smad7 both in VSMC and in the transplanted kidney. In contrast, MMF and Rapa down-regulated gene expression and protein production of TGF-beta1, smad2, 3 while up-regulating expression of smad7. There was no significant difference between the CsA group and the FK506 group, as well as the MMF group and the Rapa group. The group treated with CsA + MMF was similar to the MMF and the Rapa groups. CONCLUSION: Our study suggested that various immunosuppressants affected differentially TGF-beta1 and Smads signal pathways in rat VSMC and kidney grafts. CsA and FK506 can cause CAN, owing to up-regulated expression of smad2 and smad3, and down-regulation of smad7 expression. MMF and Rapa can prevent the CAN progression, because of down-regulation of the expression of smad2 and smad3, with increased smad7 production.     

Enhancement of chronic cyclosporine nephrotoxicity by sodium depletion in an experimental mouse model

Summary: The major adverse reaction to cyclosporine A (CsA) is chronic nephrotoxicity. to elucidate the pathogenesis of CsA nephrotoxicity and the potential role of the renin-angiotensin system (RAS) in mediating this toxicity, a reliable mouse model would enable us to take advantage of various probes, and gene knockout animals available in this species, but not in the rat, would be extremely useful. Using the manoeuvre of sodium depletion and activation of RAS, an experimental model in the mouse has been developed to reproduce structural and functional characteristics of chronic CsA nephrotoxicity in humans. Mice were treated with CsA subcutaneously at dosages of 10 mg/kg per day and 30 mg/kg per day or olive oil as a placebo on a low sodium diet (LS) (0.01% sodium) for 28 days. Comparisons were made with mice treated with CsA at 100 mg/kg per day on a normal sodium diet (NS; 0.4% sodium) for 56 days. Cyclosporine A treatment induced significant increases in serum creatinine and blood urea nitrogen (BUN) and a decrease in creatinine clearance in mice on LS ( P <0.05 vs placebo). Sodium-depleted animals on CsA 30mg/kg per day treatment developed significant histological lesions in the kidneys consisting of tubulointerstitial fibrosis, arteriolopathy, nephrocalcinosis, and tubular injury after 28 days ( P <0.001 vs placebo). By contrast, CsA treatment in mice on NS did not induce functional and structural abnormalities in the kidneys even up to 56 days at a higher dose. This mouse model can be useful to gain further insights into the pathogenetic mechanisms of chronic CsA nephropathy.     

Conversion from cyclosporine A to mycophenolate mofetil protects recipient kidney and prevents intimal hyperplasia in rat aortic allografts

BACKGROUND: Recent studies have demonstrated that complete conversion from cyclosporine A (CsA) to mycophenolate mofetil (MMF) prolongs graft survival in patients undergoing clinical organ transplantation. We investigated the effects of conversion from CsA to MMF on recipient kidneys and transplant arteriosclerosis in a rat aortic allograft model as a high responder combination. METHODS: DA (MHC haplotype, RT1a) rat abdominal aortic grafts were orthotopically transplanted into Lewis (RT1l) rats. The recipients were divided into four oral treatment groups: (1) vehicle group, (2) CsA group (15 mg/kg/day), (3) CsA/MMF40 group (conversion from CsA 15 mg/kg/day to MMF 40 mg/kg/day on day 14), and (4) CsA/MMF20 group (conversion from CsA 15 mg/kg/day to MMF 20 mg/kg/day on day 14). On day 28 after transplantation, the rats were sacrificed and the hematoserological parameters were analyzed. The grafted aortas and recipient kidneys also were evaluated histologically and immunohistochemically. RESULTS: The CsA group developed serological renal dysfunction, arteriolar hyalinosis, and apoptosis in the recipient kidneys, whereas the CsA/MMF40 and CsA/MMF20 groups did not. In the vehicle group, we observed remarkable intimal hyperplasia and marked inflammatory cell infiltration including macrophages and T cells. In the CsA group, intimal hyperplasia was evident without infiltration of macrophages or T cells. In the CsA/MMF40 and CsA/MMF20 groups, intimal hyperplasia was abrogated, while adventitial infiltration of and adhesion to the endothelium by macrophages and T cells occurred. CONCLUSIONS: Conversion from CsA to MMF protected recipient kidneys and prevented transplant arteriosclerosis. However, insufficient immunosuppression by MMF might reactivate immune cells. This conversion therapy has preventive potential in transplant patients with CsA-associated nephrotoxicity and transplant arteriosclerosis.     

Combination therapy with sirolimus and mycophenolate mofetil: effects on the kidney and on transforming growth factor-beta1

Sirolimus (SRL) is not nephrotoxic, but it has been shown to increase transforming growth factor (TGF)-beta. We investigated the effect of combining mycophenolate mofetil (MMF) with SRL on renal structure and function and on TGF-beta1. Rats treated with vehicle (VH), MMF 10 mg/kg/d, SRL 0.3 mg/kg/d, or SRL+MMF were killed at 28 days. The physiologic and histologic changes and expression of TGF-beta1, plasminogen activator inhibitor-1, and extracellular matrix proteins were studied. Although SRL alone did not alter renal function and structure, it increased TGF-beta1 mRNA by 44% and protein by 48% (P <0.05 vs. VH). Treatment with MMF did not affect TGF-beta1. When combined with SRL, MMF decreased TGF-beta1 expression to VH levels. A similar trend was observed with plasminogen activator inhibitor-1 and extracellular matrix proteins. The long-term consequence of increased TGF-beta in SRL-treated kidneys remains unknown. However, because MMF can reverse this trend, SRL and MMF combination therapy may be protective.     

Role of intrarenal endothelin 1, endothelin 3, and angiotensin II expression in chronic cyclosporin A nephrotoxicity in rats

Endothelin 1 (Et1) is widely expressed in the kidney and is related to several functions and to pathological conditions with progression towards sclerosis. The function of endothelin 3 (Et3) at the renal level is debatable, but it could have an important regulatory function in the reabsorption of water through its action on tubular type B receptors. Angiotensin II has recently been implicated as the principal factor responsible for the progression of interstitial fibrosis induced by cyclosporin A (CsA). We investigated this relationship in vivo and analyzed the modifications induced by CsA toxicity in Sprague-Dawley rats treated with 25 mg/kg/day of CsA for 28 and 56 days. Immunohistochemical methods and molecular analysis were used to study the expression of Et1 and Et3 and immunohistochemistry alone to determine the intrarenal expression of angiotensin II. Rats treated with CsA developed chronic nephrotoxicity lesions; semiquantitative analyses of hyaline arteriolopathy revealed that the passage of time affected the extent of this lesion and led to the diminution of the total glomerular area. Immunohistochemical results showed that chronic CsA treatment induced moderate secretion of Et1 and Et3 at tubular and glomerular levels and that the local expression of angiotensin II in the treatment groups was more evident than in control animals. Besides, the mRNA levels of preproEt3 showed a dramatic increase from 28 days after CsA treatment (control group 0.07+/-0.11 vs. CsA group 0.48+/-0.11, p<0.01), while the mRNA levels of preproEt1 increased from 56 days (control group 0.15+/-0.05 vs. CsA group 0.34+/-0.09, p< 0.05). At 28 days, renal lesions correlated strongly with the mRNA levels of Et3 (r>0.50, p<0.01). However, at 56 days, the key finding was the strong correlation of the most important analytical, histological, and immunohistochemical parameters of CsA nephrotoxicity with Et1 mRNA levels (r>0.50, p<0.01). These results support the hypothesis that the clinical and morphological phenomena linked with CsA nephrotoxicity are related to hypersecretion of endothelins and local expression of angiotensin II in the outer medulla and medullary rays; Et3 and angiotensin II are the first to act, followed subsequently by Et1.     

Expression of TGF-beta and fibrogenic genes in transplant recipients with tacrolimus and cyclosporine nephrotoxicity

BACKGROUND: Long-term treatment with cyclosporine (CsA) or tacrolimus (Tac) results in chronic nephrotoxicity. Transforming growth factor-beta (TGF-beta) and other pro-fibrogenic molecules have been known to contribute to this side effect. A comparison of intrarenal expression of TGF-beta and other fibrogenic genes in biopsies from patients with either CsA or Tac nephrotoxicity have not been documented. This study compared the expression of TGF-beta, collagen, fibronectin, metalloproteinases (MMP-2, -9), tissue inhibitors of metalloproteinases (TIMP-2) and osteopontin in renal biopsies obtained from renal transplant recipients treated with either CsA or Tac as primary immunosuppressive agents. METHODS: Using RT-PCR, intrarenal expression of TGF-beta, collagen, fibronectin, MMP-2, MMP-9 and TIMP-2 were studied in renal biopsies from patients with histological diagnosis of CsA or Tac nephrotoxicity and acute rejection. TGF-beta protein expression was studied by staining section of biopsies with anti-TGF-beta antibody. RESULTS: Intrarenal expression of TGF-beta, collagen, fibronectin, MMP-2, TIMP-2, and osteopontin were significantly increased in patients treated with Tac nephrotoxicity compared with CsA nephrotoxicity. The intrarenal mRNA expression of these genes was higher in patients diagnosed with Tac/CsA nephrotoxicity compared to acute rejection. CONCLUSIONS: This study compares the intrarenal expression of TGF-beta and profibrogenic genes in renal transplant recipients treated with Tac and CsA. The results show that patients diagnosed with Tac nephrotoxicity exhibit increased expression of profibrogenic genes compared to CsA nephrotoxicity.     

雷帕霉素对环孢素A诱导的慢性肾毒性的影响

目的　了解雷帕霉素 (RPM)对环孢素A(CsA)诱导的慢性肾毒性的影响。方法　对进低盐饮食的大鼠给予RPM与CsA溶剂、RPM (0 .5mg·kg-1·d-1与 1mg·kg-1·d-1)、CsA (4mg·kg-1·d-1与 8mg·kg-1·d-1)以及两者联用 ,均用药 2 8d。结果　接受RPM 1mg·kg-1·d-1的大鼠血糖明显升高 ,加重CsA(4mg·kg-1·d-1)诱导的慢性肾毒性作用 ;而亚治疗剂量的RPM (0 .5mg·kg-1·d-1)与CsA(4mg·kg-1·d-1)联用只引起轻度的血糖上升及肾小管细胞受损与间质纤维化 ,与前者相比 ,P <0 .0 5。治疗剂量的RPM(1mg·kg-1·d-1)与CsA(8mg·kg-1·d-1)联用则导致更为显著的肾功能受损、结构改变与高糖血症。结论　亚治疗剂量的RPM与CsA的联用可协同产生慢性肾毒性作用     

Comparison of expression of TGF-beta1, its receptors TGFbeta1R-I and TGFbeta1R-II in rat kidneys during chronic nephropathy induced by cyclosporine and tacrolimus

OBJECTIVE: Chronic rejection is a major cause of graft dysfunction after kidney transplantation. Long-term treatment with cyclosporine (CsA) or tacrolimus (FK506) results in chronic nephrotoxicity. Transforming growth factor-beta1 (TGFbeta1) and its receptors type I (TR-I) and type II (TR-II) have been known to contribute to this side effect. The expression of TGF-beta1, TR-I, and TR-II in rat kidneys has not been compared during chronic nephropathy induced by CsA or FK506. METHODS: Rat models of chronic CsA- or FK506-induced nephropathy were established using Sandimun Neoral or Prograf administration. The kidneys were dissected and TGF-beta1, TR-I, and TR-II proteins and TR-I and TR-II mRNAs measured by immunohistochemistry and in situ hybridization, respectively, to compare the results of the two groups. RESULTS: The functional and morphologic studies showed that in the rats the nephrotoxic effects of FK506 were not as significant as those of CsA. The results of immunohistochemistry and in situ hybridization showed that the expression of renal TGFbeta1, TR I, TR-II proteins and TR and TR II mRNA in the FK506 group were lower than those in the CsA groups. CONCLUSION: These results showed that both FK506 and CSA display nephrotoxicity, but that the nephrotoxicity of FK506 was less than that of CsA in chronic nephropathy.     

Differentiation between chronic rejection and chronic cyclosporine toxicity by analysis of renal cortical mRNA

BACKGROUND: In kidney transplantation, chronic allograft nephropathy (CAN) is the major cause of graft loss. Causes of CAN include chronic rejection and chronic cyclosporine A (CsA) nephrotoxicity. It is necessary to differentiate between these two entities in order to apply the appropriate therapeutic regimen for the individual patient, but this is hampered by the lack of discriminating functional and morphologic parameters. We investigated whether renal cortical mRNA levels for several matrix proteins can serve as discriminating parameters. METHODS: Patients with chronic rejection (N= 19) and chronic CsA toxicity (N= 17) were selected by clinical and histologic criteria. Protocol biopsies without histologic abnormalities, taken at 6 months after transplantation from patients receiving CsA, were used as controls (N= 6). Total RNA was extracted from the renal biopsy tissue, and mRNA levels of transforming growth factor-beta (TGF-beta) and the extracellular matrix (ECM) molecules collagen Ialpha1, IIIalpha1, IValpha3, decorin, fibronectin, and laminin beta2 were measured by real-time polymerase chain reaction (PCR). RESULTS: In both patient groups, the mean collagen IValpha3 and fibronectin mRNA levels were significantly elevated compared to those in controls, whereas only in CsA toxicity were the laminin beta2 and TGF-beta mRNA levels significantly increased. The increase of laminin beta2 and TGF-beta mRNA levels was significantly higher in the CsA toxicity group than in the chronic rejection group (P < 0.001 and P= 0.004, respectively). Receiver-operating characteristic (ROC) curve analysis showed that with a 15.6-fold increase in laminin beta2 mRNA expression as cut-off point, the presence of CsA toxicity could be predicted with an 87% sensitivity and an 88% specificity. CONCLUSION: Renal laminin beta2 and TGF-beta mRNA levels can be used to differentiate between chronic rejection and chronic CsA toxicity in renal transplants. The method of mRNA quantification might be applicable as an additional diagnostic tool in clinical practice.     

Inhibition of nuclear factor-kappaB activation by pyrrolidine dithiocarbamate prevents chronic FK506 nephropathy

BACKGROUND: Chronic tacrolimus (FK506) nephrotoxicity is characterized by renal fibrosis with interstitial inflammation. Since nuclear factor-kappaB (NF-kappaB) plays a key role in chronic inflammatory diseases including renal disease, the present study was conducted to elucidate the role of NF-kappaB in the pathogenesis of chronic FK506-induced nephropathy. METHODS: FK506 (1 mg/kg/day, SC) was administered daily to rats maintained on low sodium diet for 42 days. Some rats were treated with a putative NF-kappaB inhibitor, pyrrolidine dithiocarbamate (PDTC; 100, 200 mg/kg/day, by gavage). The renal function, renal histology, renal NF-kappaB-DNA binding activity and gene expression profile were examined. RESULTS: FK506 caused a decline in glomerular filtration and induced characteristic renal morphologic changes including arteriolopathy, tubular atrophy and interstitial fibrosis. FK506 markedly activated renal cortical NF-kappaB-DNA binding. PDTC administration inhibited NF-kappaB-DNA binding activity in a dose dependent manner. With higher dose, NF-kappaB-DNA binding activity was decreased to a control level. PDTC had little effect on FK506-induced renal dysfunction. Renal cortical monocyte/macrophage infiltration observed in FK506-treated rats was dramatically suppressed by PDTC. FK506 up-regulated renal cortical gene expression of chemoattractant proteins, monocyte chemoattractant protein-1 (MCP-1) and osteopontin. PDTC significantly blocked MCP-1 gene expression but had no effect on osteopontin gene expression. Tubular atrophy and tubulointerstitial fibrosis, but not arteriolopathy, were significantly attenuated by PDTC. FK506 increased renal mRNA expression of fibrogenic molecules and extracellular matrices that also were attenuated by PDTC treatment. CONCLUSIONS: NF-kappaB plays an important role in mediating cortical monocyte/macrophage infiltration and in the pathogenesis of tubular injury and interstitial fibrosis in experimental FK506-induced chronic nephropathy.     

Transforming growth factor-beta1, vascular endothelial growth factor, and bone morphogenic protein-7 expression in tacrolimus-induced nephrotoxicity in rats

The aim of our study was to investigate transforming growth factor (TGF)-beta1, vascular endothelial growth factor (VEGF), and bone morphogenic protein-7 (BMP-7) expression in the rat model of chronic tacrolimus (TAC) toxicity compared to healthy controls. Seventeen male Wistar rats were divided into two groups: group 1 animals were healthy controls and Group 2 animals were treated with TAC (1 mg/kg per day intraperitoneally for 8 weeks). At the end of the study period the animals were sacrificed following renal function studies including blood urea nitrogen (BUN), serum creatinine, and creatinine clearance, and renal tissues were examined by light microscopy for the findings of tacrolimus toxicity, specifically for afferent arteriolopathy and interstitial fibrosis. TGF-beta1, VEGF, and BMP-7 expression were assessed by semiquantitative scoring of the immunohistochemically stained specimens. Mean TAC levels were 5.53 +/- 2.38 ng/mL in group 2. BUN, creatinine levels, and creatinine clearance were 57.99 +/- 11.13 vs 39.49 +/- 5.64 mg/dL; 0.60 +/- 0.16 vs 0.65 +/- 0.09 mg/dL; 0.97 +/- 0.39 vs 1.17 +/- 0.32 mL/min in group 2 versus group 1. Only the BUN level was significantly higher in group 2 compared to group 1. Afferent arteriolopathy and interstitial fibrosis were significantly increased in group 2 compared to group 1. TGF-beta1 and VEGF expression was significantly increased while BMP-7 expression was significantly decreased in group 2 versus group 1. In conclusion, our findings suggest that TAC-induced nephrotoxicity is associated with increased TGF-beta1 and VEGF and decreased BMP-7 expression.     

Influence of the hepatic drug-metabolizing enzyme-inducer phenobarbitone on cyclosporine nephrotoxicity and hepatotoxicity in renal-allografted rats

We have investigated the influence of phenobarbitone ([PB]; 40 mg/kg/day), an inducer of hepatic drug metabolism, on high-dose cyclosporine ([CsA] 40 mg/kg/day) nephrotoxicity in normal Lewis (Lew) and renal allografted (DA X Lew F1----Lew) rats of both sexes. In untreated normal animals, CsA nephrotoxicity, assessed biochemically and histologically, in terms of acute and chronic renal structural damage, was consistently greater in male than in female rats. The capacity of PB to induce CsA metabolism was accompanied in normal rats by reductions in nephro- and hepatotoxicity and by prolonged survival of both female and male rats. Similar reductions in CsA-induced renal functional impairment and acute tubular cell injury were achieved in transplanted female (but not male) animals by concomitant PB administration. Continuous PB treatment in transplanted rats was, however, associated with the appearance of hepatic necrosis. While this effect of PB, and its failure to reduce CsA-induced chronic renal damage mitigate against its prospective value in reversing CsA toxicity, PB may nevertheless prove valuable in assessing further the role of drug metabolism in the pathogenesis of CsA nephrotoxicity.