Vitamin D attenuates renal fibrosis

In addition to pleiotropic beneficial effects of vitamin D on musculoskeletal system, immune system, cancer prevention, mortality, cardiovascular and mental health, there is increasing evidence in the recent years for its role in attenuating renal fibrosis in various animal models. An article by Zhang and colleagues in the current issue of JASN (Zhang et al JASN, June 2010) is the latest in the series. In this study, Vitamin D Receptor (mediator of action of active vitamin D) knock out mice developed more severe renal damage, compared to wild type mice, following unilateral ureteral obstruction. There was significant induction of fibrogenic and inflammatory mediators like fibronectin, collagen I, TGF-b, MCP-1 etc. Administration of Losartan eliminated the difference in fibrosis between VDR knockout and wild type mice. There are also handful of human studies that showed antiproteinuric effect of active vitamin D. The trial with largest number of patients was published in 2005 (Agarwal et al, Kidney Int. 2005). In this study, 220 stage 3 and 4 CKD patients with secondary hyperparathyroidism were randomized to oral paricalcitrol or placebo. There was reduction of proteinuria independent of use of RAAS blockers. Do these data support a role for active vitamin D in attenuating progression of CKD? May be.