The role of renin-angiotensin system in the chronic allograft nephropathy: an immunohistochemical study

Background: Evidences suggest a role of renin-angiotensin system (RAS) in the development of chronic allograft injury. Methods: We correlated intrarenal angiotensin-converting enzyme, angiotensin II (Angio II) and transforming growth factor beta(1) (TGF beta(1)) expression in 58 biopsies-proven chronic allograft nephropathy (CAN) with tissue injury and allograft survival. Results: The biopsies with CAN were graded according to Banff classification as I (22 cases), II (17) and III (19); 27 biopsies also showed a mononuclear inflammatory infiltrate in scarred areas. There were increased expression of angiotensin converting-enzyme (ACE), Angio II and TGF beta(1) mainly in tubulointerstitial compartment in the group with CAN; there was no association of Angio II and TGF beta(1) expression with interstitial fibrosis. There were no significant differences of ACE, Angio II and TGF beta(1) expression between the patients treated and untreated with RAS blockade, and with the graft outcome. Interstitial inflammatory infiltrate had positive correlation with interstitial fibrosis and significant impact on graft survival at 8 years. Conclusions: Our study showed in a group of cases with CAN a high percentage of inflammatory infiltrate that correlated with interstitial fibrosis and graft outcome. The chronic inflammatory changes in these cases did not show significant association with local RAS expression.