Chronic Allograft Nephropathy In Rats Research Articles

SDF‑1/CXCR4 induces epithelial‑mesenchymal transition through activation of the Wnt/β‑catenin signaling pathway in rat chronic allograft nephropathy.

Epithelial-mesenchymal transition (EMT) has been demonstrated to serve a crucial role in the progression of interstitial fibrosis, which is one of the principal pathological features of chronic allograft nephropathy (CAN). However, to the best of our knowledge, the mechanisms of EMT in CAN have not been investigated. In the present study, the effect of stromal cell-derived factor 1 (SDF-1) and the Wnt signaling pathway on the progression of EMT following kidney transplantation was investigated. The CAN model was established using Fisher 344 and Lewis rats, treated with low-dose cyclosporine with or without AMD3100. CAN was confirmed by the pathological alterations and chronic allograft damage index scoring, and EMT was confirmed by western blotting and reverse transcription-quantitative polymerase chain reaction. In the AMD3100 group, there were lower expression levels of α-SMA and higher expression levels of E-cadherin, which indicated that CAN and EMT were ameliorated by AMD3100. The kidney tissue was analyzed using an mRNA + long noncoding (lnc)RNA microarray. A total of 506 mRNAs and 404 lncRNAs were demonstrated to be significantly differentially expressed between the two groups, which revealed the involvement of SDF-1/CXC chemokine receptor 4 (CXCR4) and the Wnt pathway. SDF-1 was demonstrated to induce EMT in vitro through the upregulation of α-SMA, downregulation of E-cadherin and the wound healing assay, and in the rat renal tubular epithelial cells via the nuclear accumulation of β-catenin, which were all inhibited by either AMD3100 or DKK-1. CXXC finger protein 5 (CXXC5), a negative regulator of the Wnt pathway, was downregulated following treatment with SDF-1, which was inhibited by AMD3100 but not by DKK-1. Thus, CXXC5 may be a regulator downstream of SDF-1/CXCR4 in EMT. In conclusion, SDF-1/CXCR4 induces EMT of renal tubular epithelial cells with the involvement of the Wnt pathway, which may be a novel mechanism and therapeutic target in kidney allograft fibrosis of rats.

Use of Contrast-Enhanced Ultrasonography to Evaluate Chronic Allograft Nephropathy in Rats and Correlations between Time-Intensity Curve Parameters and Allograft Fibrosis

This study quantitatively analyzed changes in the hemodynamic characteristics of renal allografts at different stages in a rat chronic allograft nephropathy (CAN) model as well as the relationship between hemodynamic parameters and renal allograft fibrosis using contrast-enhanced ultrasonography (CEUS). The experimental group used a CAN rat model (n = 30), and the control group used an orthotopic syngeneic renal transplant model (n = 30). After surgery, creatinine clearance rates were regularly monitored every 2 wk. The checking times were set at 4, 12 and 24 wk after surgery, which represent early, middle and late stage of CAN, respectively. At different stages of CAN, eight rats from each group were randomly selected for CEUS examination. Time-intensity curve (TIC) parameters, including rise time, peak intensity, mean transit time, area under the curve, wash-in slope, time-to-peak and α-smooth muscle actin (α-SMA) expression; Vimentin expression; and chronic allograft damage index scores were evaluated by linear correlation analysis. Before the creatinine clearance rate showed significant abnormalities, the renal allografts in the experimental group had already presented pathologic changes associated with CAN. In the early stage after surgery, compared to the TIC curve of the control group, the experimental group showed increased rise time, mean transit time, area under the curve and time-to-peak, and decreased wash-in slope (p < 0.05). Chronic allograft damage index scores and the expression levels of α-SMA and Vimentin proteins in renal allografts were correlated with TIC parameters (p < 0.05). Compared to creatinine clearance rate, CEUS can detect CAN at earlier stages. The correlations between TIC-related parameters and the expression levels of α-SMA and Vimentin in renal allografts indicate that CEUS is a feasible way to assess the degree of renal allograft fibrosis quantitatively.

Increased Expression of p-Akt correlates with Chronic Allograft Nephropathy in a Rat Kidney Model.

Chronic allograft nephropathy (CAN) is the most common cause of chronic graft dysfunction leading to graft failure, our study investigates the expression and significance of p-Akt in the pathogenesis of CAN in rats. Kidneys of Fisher (F344) rats were orthotopically transplanted into Lewis (LEW) rats. The animals were evaluated at 4, 8, 12, 16, and 24 weeks post-transplantation for renal function and histopathology. Phosphorate Akt (p-Akt) protein expression was determined by Western blot and immunohistological assays. Our data show that 24-h urinary protein excretion in CAN rats increased significantly at week 16 as compared with F344/LEW controls. Allografts got severe interstitial infiltration of mononuclear cells at week 4 and week 8, but it was degraded as the time went on after week 16. Allografts markedly presented with severe interstitial fibrosis (IF) and tubular atrophy at 16 and 24 weeks. p-Akt expression was upregulated in rat kidneys with CAN, and the increase became more significant over time after transplantation. p-Akt expression correlated significantly with 24-h urinary protein excretion, serum creatinine levels, tubulointerstitial mononuclear cells infiltration, smooth muscle cells (SMCs) migration in vascular wall, and IF. It was concluded that p-Akt overexpression might be the key event that involved mononuclear cells infiltration and vascular SMCs migration at early stage, and IF and allograft nephroangiosclerosis at the late stage of CAN pathogenesis in rats.

Early treatment with xenon protects against the cold ischemia associated with chronic allograft nephropathy in rats

Chronic allograft nephropathy (CAN) is a common finding in kidney grafts with functional impairment. Prolonged hypothermic storage-induced ischemia-reperfusion injury is associated with the early onset of CAN. As the noble gas xenon is clinically used as an anesthetic and has renoprotective properties in a rodent model of ischemia-reperfusion injury, we studied whether early treatment with xenon could attenuate CAN associated with prolonged hypothermic storage. Exposure to xenon enhanced the expression of insulin growth factor-1 (IGF-1) and its receptor in human proximal tubular (HK-2) cells, which, in turn, increased cell proliferation. Xenon treatment before or after hypothermia-hypoxia decreased cell apoptosis and cell inflammation after reoxygenation. The xenon-induced HK-2 cell proliferation was abolished by blocking the IGF-1 receptor, mTOR, and HIF-1α individually. In the Fischer-to-Lewis rat allogeneic renal transplantation model, xenon exposure of donors before graft retrieval or recipients after engraftment enhanced tubular cell proliferation and decreased tubular cell death and cell inflammation associated with ischemia-reperfusion injury. Compared with control allografts, xenon treatment significantly suppressed T-cell infiltration and fibrosis, prevented the development of CAN, and improved renal function. Thus, xenon treatment promoted recovery from ischemia-reperfusion injury and reduced susceptibility to the subsequent development of CAN in allografts.

Chronic Allograft Nephropathy in Rats Is Improved by the Intervention of Rhein

AimIn this study, we investigated the therapeutic efficacy and potential mechanisms of rhein to mitigate chronic allograft nephropathy (CAN) in rats. Materials and MethodsFisher rat donors and Lewis rat recipients were used to establish the CAN model. Thirty rats with transplanted kidneys were randomly divided into two groups: 16 untreated and 14 rhein = treated rats. Five Lewis rat controls underwent removal of their right kidneys. The Intervention group was administered rhein oral solution (100 mg kg-1 d-1) by gavage after transplantation. The untreated and control groups were given 0.5% sodium carboxymethyl cellulose. Blood and urine samples were collected at 4, 8, and 16 weeks to examine renal function and total urine protein. Half of the rats in each group were sacrifice at 8 or 16 weeks to examine renal pathology. Immunohistochemical examination and real-time polymerase chain reaction of renal tissues were performed to detect expressions of transforming growth-β1(TGF-β1), hepatic growth factor (HGF), bone morphogenetic protein 7 (BMP7), frobronectin, and collgen IV. ResultsRhein improved renal function and significantly reduced renal fibrosis and interstitial inflammation. The levels of BMP7 and HGF were significantly elevated in the renal tissues of the rhein intervention group. In the meantime, fibronectin and collagen IV were decreased in the extracellular matrix. The expression of TGF-β1 was similar between these two groups. ConclusionRhein improved renal function and reduced renal fibrosis and interstitial inflammation by inducing production of HGF and BMP7.

Effect of Spironolactone on Chronic Allograft Nephropathy in Rats

Objective: Chronic allograft nephropathy (CAN) is common following renal transplantation in cats and people. Aldosterone potentiates ongoing renal injury; however its role in CAN is less defined. Spironolactone, an aldosterone receptor blocker, is protective in other rodent models of renal injury. The purpose of this study was to evaluate spironolactone on the development of CAN in a rat model Animals: Fisher and Lewis, adult, male rats. Procedures: A Lewis to Fisher model of CAN was used. Rats were divided into 4 groups, 2 nephrectomy controls (CON) and 2 transplantation (TX) groups. Two groups (a CON and TX) received tap water (0.25 ml/day orally), and the remaining 2 received spironolactone (10 mg/kg orally) daily for 16 weeks post transplantation. Serum creatinine concentration, urine-protein: urine-creatinine (UP: UC), and changes in renal cortex gene expression were measured during and at 16 weeks after transplantation. Results: There were no significant differences in any of the outcome measures when the 2 TX groups were compared. TX rats had significantly more (p=0.0002) histological lesions consistent with CAN and elevation in TNF-α (p=0.0402) compared to CON animals. Conclusions and clinical relevance: In this study, spironolactone did not protect against the development or progression of CAN. Impact for human medicine: The impact of aldosterone on the occurrence of CAN in humans following renal transplantation remains an area of investigation.

Therapeutic effect of low-dose aspirin on chronic allograft nephropathy in renal recipient rats

Objective To observe the effect of low-dose aspirin on allogeneic chronic allograft nephropathy in renal recipient rats and the possible mechanisms.Methods Chronic allograft nephropathy model of rats were established and the recipient rats were randomly divided into 2 groups with 10 in each group.Cyclosporine A (5 mg/kg) was administered as a basic treatment one day before surgery to prevent and treat acute rejection.Aspirin therapy group was given oral aspirin (5 mg/kg) daily,and control group were given oral saline 2 ml/d.Animals were sacrificed 8 weeks after operation and the serum creatinine,urea nitrogen levels were determined.Renal histomorphology and immunohistochemistry approaches were used to examine TGF-β1 expression.Results The severity of pathological lesion,increase of serum creatinine and blood urea nitrogen levels,and expression of fibrosis associated factor TGF-β1 in aspirin therapy group were significantly slighter than those of the saline control group(P0.05).Conclusion Low-dose aspirin in addition to routine anti-rejection treatment can be used for treatment of chronic allograft nephropathy in rats,which might be associated with the decreased expression of anticoagulation factor TGF-β1.

Therapeutic Effect of Y-27632 on Chronic Allograft Nephropathy in Rats

Chronic allograft nephropathy (CAN) is a major cause of late allograft loss. Recent evidences suggest that Rho and its downstream effector ROCK may be greatly involved in the progression of renal fibrosis. Inhibition of Rho/ROCK pathway might interact with the inflammatory process in the renal interstitium, and antagonize the process of epithelial-to-mesenchymal transition (EMT). We hypothesized that Y-27632 could inhibit the chronic inflammatory process and prevent the progression of CAN. Fisher (F344) kidneys were orthotopically transplanted into Lewis rat recipients. Lewis to Lewis rat kidney transplantation was served as the syngeneic control (Syn group). Allograft recipients were randomized and treated with either cyclosporine A alone (Allo group), or in combination with Y-27632 (30 mg/kg body weight/d intragastric, Y-27632 group). Renal function and urine protein excretion levels of the rats were analyzed. Animals were sacrificed 12 wk post-transplantation for histological and immunohistochemical studies, as well as analysis of the expression levels of chemokines, transforming growth factor (TGF-beta) 1 and alpha smooth muscle actin (alpha-SMA). Renal function deteriorated progressively in the Allo group, and there was typical CAN morphology in the kidneys. However, Y-27632-treatment significantly prevented the deterioration of graft function, lessened the level of urine protein excretion, and preserved the renal structure. Attenuation of ED1 positive mononuclear cell infiltration and amelioration of tubulointerstitial fibrosis were achieved by Y-27632 intervention. This was associated with down-regulation of the expression of tubular monocyte chemoattractant protein-1, RANTES (regulated upon expression normal T cell expressed and secreted), and phosphorylated NF-kappaB (which was a marker for activation). Profibrotic protein (TGF-beta1) and alpha-SMA, a marker of EMT, were significantly down-regulated by Y-27632 treatment as well. The Rho/ROCK pathway plays an important role in the progression of CAN, and specific inhibition of Rho activity by Y-27632 showed favorable effects on blocking renal interstitial inflammation and fibrosis, thus efficiently retarding the development of CAN, which might provide us with a novel strategy to improve long-term renal graft survival.

C4d Deposition Is Associated With Chronic Allograft Nephropathy in Rats and Could Be Influenced by Immunosuppressants

Aims Deposition of C4d in peritubular capillaries (PTC) has been considered to be a marker of humoral immunity in renal transplant. This study is to investigate C4d deposition in rat renal allografts undergoing CAN and the effects of immunosuppressants on it. Methods Fisher 344 rat renal grafts were orthotopically transplanted into Lewis rats following the procedure of Kamada with our modification. All the recipients were given CsA 10 mg/kg −1 · d −1 × 10 d and then divided into 5 groups (each n = 9); (1) Vehicle: vehicle orally, (2) CsA: 6 mg/kg −1 · d −1, (3) RAPA: 0.8 mg/kg −1 · d −1, (4) FK 506: 0.15 mg/kg −1 · d −1, (5) MMF: 20 mg/ kg −1 · d −1. At 4 weeks, 8 weeks, 12 weeks, the rats were sacrificed, renal allografts were harvested and sera were collected. The deposition of C4d was detected by immunofluorescence and analyzed by Integrated Optical Density (IOD). The pathological changes were accessed according to the Banff 97 criteria. Results C4d deposition in PTC was found in all the allografts at 4 weeks, while there was no obvious manifestations of CAN in all the groups; the differences of Banff Score between all groups were not significant ( P > .05). The values of IOD in RAPA and MMF group were lower than those in other 3 groups ( P = .002, .006). The differences between RAPA and MMF, and between other 3 groups were not significant ( P > .05). The intensity of C4d increased along with the progression of CAN, the heaviest C4d deposits in PTC were found at 12 weeks, and meanwhile the severest CAN was found. Comparing with Vehicle group, CsA and FK 506 had no effect on C4d deposition ( P > .05), however, MMF and RAPA obviously decreased the C4d deposition ( P = .000). The intensity of C4d deposition had a significant correlation with the severity of CAN ( r = 0.894, P = .000). Conclusions Our study suggests that the deposition of C4d in allografts appears earlier than pathological changes of CAN and has a correlation with the progression of CAN. MMF and RAPA can attenuate CAN by inhibiting humoral immunity. In contrast, CsA and FK 506 have no effect on humoral immunity.

SDF-1 Plays a Key Role in Chronic Allograft Nephropathy in Rats

Objectives Our previous study demonstrated that anti-stromal cell derived factor-1 (SDF-1) antibody delayed graft arteriosclerosis in rat abdominal aortic grafts. In this study, we investigated the mechanisms of SDF-1 on chronic allograft nephropathy (CAN), and whether SDF-1 antibody had protective effect on CAN. Methods Male Lewis rats that received left renal grafts from male Fisher 344 rats were randomly divided into three groups: group A only received cyclosporine (CsA; 10 mg · kg −1 · d −1) every day; group B received anti–SDF-1 antibody (8 μg · kg −1 · d −1) + CsA (10 mg · kg −1 · d −1); and group C, an isograft control (Fisher 344 to Fisher 344). All recipient animals were unilaterally right nephrectomized. Group A and B grafts were preserved in 4°C UW solution for 1 hour prolonged cold ischemia. Masson and hematoxylin and eosin staining were performed to evaluate glomerular sclerosis rate (GSR) and Banff score. Serum creatinine (Scr) and blood urea nitrogen (BUN) were determined as well as histologic examinations of the kidneys with immunohistochemistry for SDF-1 and CXCR4, the only known receptor of SDF-1. Results Compared with group C, ischemia and rejection produced a nine-fold increase in GSR and Banff score, as well as significant increases in Scr and BUN levels in group A. Anti–SDF-1 antibody retarded the increase by downregulating the expression of SDF-1 and CXCR4. Furthermore, there was a significant relationship between the expression of SDF-1 and the mean Banff score. Conclusion Anti–SDF-1 antibody retarded the process of CAN.

Effect of Ligustrazine on Chronic Allograft Nephropathy in Rats

Objectives Our previous study demonstrated that Ligustrazine reduced renal dysfunction associated with ischemia-reperfusion injury in mice. In this study, we investigated whether Ligustrazine herbal injection had any preventive and therapeutic effectiveness against chronic allograft nephropathy in rats. Methods Male Lewis rats that received left renal grafts from male Fisher 344 rats were randomly divided into five groups: group A only received cyclosporine (CsA; 10 mg · kg −1 · d −1) every day. Groups B, C, and D received low-dose Ligustrazine (50 mg · kg −1 · d −1) + CsA (10 mg · kg −1 · d −1); high-dose Ligustrazine (100 mg · kg −1 · d −1) + CsA (10 mg · kg −1 · d −1); and CsA (10 mg · kg −1) + mycophanolate mofetil (10 mg · kg −1 · d −1), respectively. Group E was an isografted group (Fisher 344 to Fisher 344). Grafts were preserved in 4°C University of wisconsin solution for 1 hour prolonged cold ischemia. All recipient animals were unilaterally right nephrectomized. Serum creatinine (Scr), blood urea nitrogen (BUN), urinary protein, kidney malondialdehyde (MDA) level, and superoxide dismutase (SOD) were determined, as well as examining kidney histology with immunohistochemistry for Bcl-2, and ICAM-1. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were tested to show whether Ligustrazine has side effects. Results Compared with group E, ischemia and rejection produced a ninefold increase in GSR and Banff score, as well as significant increases of Scr, BUN, and urinary protein levels in group A. High doses of Ligustrazine significantly slowed the increase ( P < .01). Ligustrazine also decreased MDA levels and ameliorated the down-regulation of SOD activity. Bcl-2 was up-regulated posttransplantation, especially in the Ligustrazine-treated group ( P < .01). The up-regulation of ICAM-1 was greatly diminished by Ligustrazine ( P < .01). Furthermore, there was little difference in ALT/AST between the Ligustrazine-treated and the isograft group. Conclusion These findings suggested that Ligustrazine could postpone chronic renal allograft dysfunction associated with cold ischemia injury and chronic allograft rejection but had no evident hepatic side effects.

Renoprotective effects of the AGE-inhibitor pyridoxamine in experimental chronic allograft nephropathy in rats

Advanced glycation end products (AGEs) are involved in diabetic nephropathy (DN). The AGE formation inhibitor pyridoxamine (PM) is renoprotective in DN and in normoglycaemic obese Zucker rats. In chronic allograft nephropathy (CAN), renal AGE accumulation occurs as well. To investigate whether inhibition of AGE formation is renoprotective in CAN, we studied the Fisher 344 to Lewis (F-L) allograft rat model of experimental CAN. Fisher to Fisher (F-F) isografts served as controls. Proteinuria, renal function and renal histology of untreated transplanted rats (F-L n = 8, F-F n = 8) were compared to rats receiving PM 2 g/l in drinking water for 20 weeks starting at transplantation (F-L n = 5, F-F n = 10). All rats received cyclosporin A (1.5 mg/kg/day) for 10 days after transplantation to prevent early acute rejection. Compared to untreated allografts, PM significantly decreased proteinuria (76 +/- 18 vs 29 +/- 3 mg/day), serum creatinine (130 +/- 12 vs 98 +/- 5 micromol/l), focal glomerulosclerosis (116 +/- 27 vs 16 +/- 5 AU), glomerular macrophage influx (5.6 +/- 0.6 vs 3.3 +/- 1.0), interstitial fibrosis (132 +/- 24 vs 76 +/- 2 AU) and interstitial macrophage influx (47.0 +/- 8.7 vs 15.4 +/- 5.0. Moreover, PM significantly ameliorated tubular accumulation of pentosidine, compared to untreated allografts (2.5 +/- 0.6 vs 0.3 +/- 0.3, all p < 0.05). In the isograft controls, these values did not differ between untreated and PM treated rats. PM exerts renoprotective effects and decreases renal pentosidine accumulation in experimental CAN, suggesting a detrimental role for renal AGE accumulation in the pathogenesis of renal damage in this non-diabetic model. These results indicate that inhibition of AGE formation might be a useful adjunct therapy to attenuate CAN.

Endothelin-Mediated Oncofetal Fibronectin Expression in Chronic Allograft Nephropathy

Chronic allograft nephropathy is a sclerotic process characterized by an increased extracellular matrix (ECM) protein deposition. Fibronectin (FN) is a major component of ECM. FN has been reported to undergo alternative splicing and produce several isoforms including the extra domain-B (ED-B) containing embryonic isoform. In the present study, we investigated ED-B FN expression in chronic allograft nephropathy and its relationship with endothelins (ET). To establish chronic allograft nephropathy, allografts were performed between Fisher 344 --> Lewis rats. Allograft recipients were then randomly divided into two groups, allografts and allografts treated with ET receptor antagonist bosentan. Lewis --> Lewis recipients were used as isograft controls. Grafts were harvested at 30, 90 and 140 days for histological and gene expression analyses with respect to ED-B FN, ET-1 and transforming growth factor-beta1 (TGF-beta1) mRNA. ED-B FN protein levels were assessed by immunohistochemical analysis. Additionally, we analyzed human renal allograft biopsies. Our data demonstrates that rat chronic allograft nephropathy is associated with progressive upregulation of ED-B FN mRNA and protein. ET-1 and TGF-beta1 mRNA were also upregulated. Treatment of allograft recipient rats with bosentan prevented upregulation of ED-B FN and TGF-beta1. We further show that total FN, ED-B FN, ET-1 and TGF-beta1 mRNA expression were upregulated in human chronic allograft nephropathy specimens. Results obtained from both human and rat renal allograft tissues suggest that expression of ED-B FN is upregulated in chronic allograft nephropathy and such upregulation is mediated via ET-1 and its interaction with TGF-beta1.

HGF gene transfer increases kidney graft survival

The introduction of cyclosporine (CsA) into clinical practice has resulted in marked improvement in the short-term outcome of organ transplantation, and 1-year survival of renal allografts has improved significantly. However, the annual rate of kidney graft loss caused by chronic allograft nephropathy (CAN) has remained stable over last decade. CAN may result from perioperative ischemia at the time of transplantation. Furthermore, chronic CsA nephrotoxicity may progress to an irreversible renal lesion characterized by tubular atrophy, striped interstitial fibrosis, hyalinosis of the afferent arteriole, and progressive renal impairment. Recent report demonstrated the therapeutic effects of hepatocyte growth factor (HGF) in preventing CAN using a well-established rat CAN model. They showed that HGF treatment during the initial 4 weeks after engraftment prevented onset of CAN and associated death and provided longlasting benefit in terms of graft survival. Exogenous HGF is very unstable in the blood circulation due to the rapid clearance by the liver. To circumvent this problem, we developed a new gene transfer system by electroporation in vivo. Therefore, this gene transfer approach represents a useful technique to investigate the therapeutic potential of HGF gene transfer for long-term survival of kidney allograft. The goal of the present study was to assess the renoprotective potential and safety of HGF gene transfer using a porcine kidney transplant warm ischemia injury model or CsA nephrotoxicity model. In the first set of experiments, following left porcine kidney removal, 10 minutes of warm ischemic injury was intentionally induced. Next, the HGF expression vector or vehicle was infused into the renal artery with the renal vein clamped ex vivo, and electric pulses were discharged using bathtub-type electrodes. Kidney grafts were then transplanted after removing the right kidney. Histopathologic examination of vehicle-transfected kidney transplant revealed initial tubular injury followed by tubulointerstitial fibrosis. In contrast, HGF-transfected kidneys showed no initial tubular damage and no interstitial fibrosis at 6 months posttransplant. In the next set of experiments, CsA was subcutaneously administered daily under low sodium diet, and HGF gene was transferred into skeletal muscle by electroporation on days 7 and 14. We also examined the antiapoptotic mechanism of HGF using human proximal tubular epithelial cells. HGF gene transfer rescued CsA-induced initial tubular injury, and suppressed interstitial infiltration of endothelium-1 (ED-1)-positive macrophages in CsA nephrotoxicity. In addition, HGF significantly inhibited tubular cell apoptosis, and increased the number of proliferating tubular epithelial cells. In vitro studies suggest that HGF executes the antiapoptotic function by enhancing the phosphorylation of Akt and Bcl-2. Northern blot analysis demonstrated that HGF gene transfer suppressed cortical mRNA levels of transforming growth factor-β (TGF-β). Consequently, HGF gene transfer significantly reduced a striped interstitial phenotypic alteration and fibrosis. We conclude that electroporation-mediated HGF gene transfection protects the kidney against graft injury.

Cytomegalovirus enhance expression of growth factors during the development of chronic allograft nephropathy in rats

Cytomegalovirus (CMV) accelerates chronic rejection (CRX) in a model of rat kidney allograft. In this model, the expressions of transforming growth factor beta 1 (TGF-beta), platelet-derived growth factor (PDGF)-AA, PDGF-BB and connective tissue growth factor (CTGF) were investigated with and without CMV. Transplantations were performed under immunosuppression. One group of animals was infected with CMV and the other was left uninfected. The grafts were harvested on days 3-60 after transplantation. Growth factor proteins were demonstrated by immunohistochemistry, and mRNAs by in situ hybridization. A significantly more intense and earlier endothelial TGF-beta (2.4 +/- 0.8 vs. 1.0 +/- 0.0; P < 0.05) and PDGF-AA (1.8 +/- 0.4 vs. 1.0 +/- 0.0; P < 0.05) expressions, confirmed by mRNA hybridization, occurred in the CMV group compared with the noninfected group. PDGF-BB appeared in a few inflammatory cells only. In addition CTGF appeared earlier and has more intense in the CMV group (2.5 +/- 0.6 vs. 1.2 +/- 0.5) and the number of CTGF mRNA-positive fibroblasts (57 +/- 9 vs. 3 +/- 4; P < 0.05) was significantly higher. Thus, CMV enhanced expression of TGF-beta1, PDGF-AA and CTGF during the development of CRX.

Inhibition of Matrix Metalloproteinases During Chronic Allograft Nephropathy in Rats

Chronic allograft nephropathy (CAN) belongs to the major causes of long-term kidney allograft failure. One of the histologic hallmarks of CAN is interstitial fibrosis, influenced by matrix metalloproteinases (MMPs) that are controlling extracellular matrix (ECM) degradation. Whether MMPs affect the development and progression of CAN is not clear so far. To analyze the role of MMPs in CAN, we investigated the effects of an early and a late application of BAY 12-9566, an inhibitor of MMP-2, -3, and -9 on the development and progression of CAN in a rat kidney-transplantation model. Fisher kidneys were orthotopically transplanted into Lewis recipients that were treated with BAY 12-9566 (15 mg/kg per day) or vehicle either for the first 10 days after transplantation (early treatment) or from week 12 to week 20 after transplantation (late treatment). Proteinuria was analyzed every 4 weeks up to week 20 after transplantation when kidney grafts were removed for further analysis. Early MMP-inhibition resulted in a significantly reduced 24-hour protein excretion that was paralleled by a lower grade of CAN after 20 weeks. However, late MMP inhibition starting at week 12 after transplantation resulted in significantly higher proteinuria and a higher grade of CAN as compared with controls. Furthermore, transforming growth factor-beta and platelet-derived growth factor-B chain mRNA levels were significantly increased in these animals. Inhibition of MMPs early after transplantation reduced the development and progression of CAN but promoted CAN if initiated at later stages. Thus, MMPs are involved in the development and progression of CAN.

Effects of progesterone and selective oestrogen receptor modulators on chronic allograft nephropathy in rats

We recently demonstrated that oestrogens ameliorate the progression of chronic allograft nephropathy (CAN). In our present study, we investigated the role of progesterone and selective oestrogen receptor modulators (SERMs) in this process. Female Fisher (F344) kidneys were orthotopically transplanted into intact or ovariectomized female Lewis recipients. Ovariectomized recipients were divided into four groups and were treated with either progesterone alone or in combination with oestradiol, oestradiol alone or vehicle. Intact recipients were divided into three groups and were treated with SERMs such as tamoxifen and one of its new derivatives, droloxifene or vehicle. Animals were harvested 24 weeks after transplantation for histological and immunohistological studies as well as for molecular analysis. Administration of progesterone resulted in increased urinary protein excretion as well as profound glomerulosclerosis and mononuclear cell infiltration. The combined treatment had similar detrimental effects on the development of CAN. In contrast, oestradiol treatment alone improved graft function, reduced glomerulosclerosis and diminished cellular infiltration. SERMs again impaired allograft function and promoted the development of CAN. Renal allograft damage paralleled intragraft mRNA expression of transforming growth factor-beta1 in all groups. Our results suggest that addition of progesterone diminishes the beneficial effects of oestrogens on the development of CAN in rats. Similarly to progesterone, SERMs worsened long-term renal allograft outcome.

Recipient age affects chronic allograft nephropathy in rats

Recipient age affects chronic allograft nephropathy in rats

Increased dietary salt accelerates chronic allograft nephropathy in rats

Chronic allograft nephropathy (CAN), a major problem in renal transplantation, is related to both alloantigen-dependent and -independent processes. Because dietary salt intake modulated glomerular production of transforming growth factor-beta, which has been shown to play an important role in CAN, we hypothesized that dietary salt would directly enhance renal injury in a rodent model of CAN. Dietary NaCl was increased from 1.0% (normal) to 8.0% in a group of Fisher/Lewis rats 25 days following orthotopic renal transplantation and was continued until 16 weeks after transplantation. Blood pressure, which was recorded using radiotelemetry in the first eight-weeks post-transplantation, did not differ between the groups, but allograft recipients on the 8.0% NaCl diet rapidly demonstrated increased urinary albumin excretion. Renal function determined by dynamic functional imaging was worse in allograft recipients on the 8.0% NaCl diet by six weeks following transplantation. Histologic examination at 16 weeks confirmed a significant increase in allograft damage in the 8.0% NaCl group compared with allografts from rats on 1.0% NaCl diet. These findings included glomerulosclerosis and tubulointerstitial injury that consisted of fibrosis, tubular atrophy and dilation, intratubular casts, and tubular epithelial cell damage. Small arteries and arterioles did not show evidence of damage from hypertension or other abnormality. In this model of CAN, renal allograft dysfunction preceded hypertension and was accelerated significantly by an increase in dietary salt.

Increased dietary salt accelerates chronic allograft nephropathy in rats

Increased dietary salt accelerates chronic allograft nephropathy in rats