| Background: Chronic allograft nephropathy (CAN) is a major cause of late allograft loss. Recent evidences suggest that aldosterone and its downstream effector TGF-β1 may be greatly involved in the progression of renal fibrosis. Inhibition of aldosterone might antagonize the process of epithelial-to-mesenchymal transition (EMT). We hypothesized that spironolactone could prevent the progression of CAN, which provide a new way of therapy to extend survival time of transplanting kidney. Materials and Methods: Fisher (F344) kidneys were orthotopically transplanted into Lewis rat recipients. Lewis to Lewis rat kidney transplantation was served as the syngeneic control (group A). Allograft recipients were randomized and treated with either cyclosporine A alone (group B), or in combination with spironolactone (20 mg/kg body weight/d, group C). Renal function and urine protein excretion levels of the rats were analyzed at 4w, 8w and 12w post-transplantation, respectively. Animals were sacrificed 12 weeks post-transplantation for histological and immunohistochemical studies, as well as analysis of the expression levels of osteopontin(OPN), transforming growth factor-1(TGF-β1) andα-SMA.Results: 1.In formal test of 40 operations on 80 rats, 34 rats were survived, the operative time of the donor's was 63±17min, and the recipient's was 59±7min, including the warm ischemia time (about 1min), and the cold ischemia time (48±10min). Achievement ratio is about 85%. The abortive cases was anastomosis of both renal veins hemorrhage and thrombosis of renal artery. 2.Renal function deteriorated progressively in group B, and there was typical CAN morphology in the kidneys. However, spironolactone treatment significantly prevented the deterioration of graft function, lessened the level of urine protein excretion, and preserved the renal structure (P<0.05). Attenuation of tubular atrophy and amelioration of tubulointerstitial fibrosis were achieved in group C. We made statistics analyse during every group. There was significant difference between group B and others (P<0.05); there was no significant difference between group A and group C (P>0.05). This was associated with down-regulation of the expression of OPN and TGF-β1, which is a marker of EMT.α-SMA was significantly down-regulated by spironolactone treatment as well. Immunohistochemistry staining showed that TGF-β1 level was markedly elevated in group B compared with group A(P<0.05); however, spironolactone therapy significantly decreased the TGF-β1 levels in the allograft kidneys(P<0.05); It had nostatistical significance that group B compared with group C(P>0.05). Renal expression of OPN significantly increased primarily in tubular cells in group B compared with group A(P<0.05); spironolactone markedly reduced OPN staining(P<0.05), with only sporadic staining noted in a few tubular cells. Absolute kidney content of OPN were determined by Western blot on tissue homogenates and was consistent with the immunohistochemistry findings. For the ANOVA ofα-SMA expression, there was significantly moreα-SMA expressed in group B compared with group A(P<0.05); spironolactone therapy markedly decreased theα-SMA levels in the allograft kidneys(P<0.05).Conclusion: 1.Aldosterone receptor blockade with spironolactone can decline the expression of TGF-β1 and OPN, then it could play effect of anti-fibrous degeneration of CAN, and slow the proceeding of CAN.2.The aldosterone plays an important role in the progression of CAN, and spironolactone showed favorable effects on blocking renal interstitial fibrosis, thus efficiently retarding the development of CAN, which might provide us with a novel strategy to improve long-term renal graft survival.
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