PDGF-D inhibition by CR002 ameliorates tubulointerstitial fibrosis following experimental glomerulonephritis

Background. Arresting or regressing kidney scarring is of major clinical relevance. Platelet-derived growth factor D (PDGF-D) is widely expressed in fibrotic kidneys. Administration of the PDGF-D neutralizing fully human monoclonal antibody CR002 in the acute phase of progressive anti-Thy 1.1 glomerulonephritis reduced glomerular and secondary tubulointerstitial damage. Methods. Using this model, we now assessed the effects of CR002 (n = 15) vs irrelevant control IgG (n = 17) administered on days 17, 28 and 35 after disease induction, i.e. after acute glomerular damage had subsided. Results. In vitro, CR002 inhibited the PDGF-D- but not the PDGF-B-induced proliferation of rat renal fibroblasts. Following the first CR002 injection on day 17, exposure to therapeutic levels was maintained until day 49. Proteinuria in the CR002-treated group was transiently reduced between days 49 and 77 (-19 to -23% in comparison with the controls; P < 0.05). On day 100, CR002 treatment reduced the number of rats that had doubled their serum creatinine (CR002: 40 vs controls: 71%; P < 0.05). Compared with controls, the CR002 animals, on day 100, significantly lowered glomerular expression of vimentin and collagens as well as tubulointerstitial damage scores, interstitial fibrosis, vimentin and cortical PDGF-D mRNA levels. Conclusions. PDGF-D antagonism, even after the phase of acute glomerular damage, exerts beneficial effects on the course of tubulointerstitial damage, i.e. the final common pathway of most renal diseases.