Infusion of angiotensin-(1–7) reduces glomerulosclerosis through counteracting angiotensin II in experimental glomerulonephritis

Abstract

Recent identification of a counterregulatory axis of the renin-angiotensin system, called angiotensin-converting enzyme 2-angiotensin-(1–7) [ANG-(1–7)]-Mas receptor, may offer new targets for the treatment of renal fibrosis. We hypothesized that therapy with ANG-(1–7) would improve glomerulosclerosis through counteracting ANG II in experimental glomerulonephritis. Disease was induced in rats with the monoclonal anti-Thy-1 antibody, OX-7. Based on a three-dose pilot study, 576 μg·kg⁻¹·day⁻¹ ANG-(1–7) was continuously infused from day 1 using osmotic pumps. Measures of glomerulosclerosis include semiquantitative scoring of matrix proteins stained for periodic acid Schiff, collagen I, and fibronectin EDA+ (FN). ANG-(1–7) treatment reduced disease-induced increases in proteinuria by 75%, glomerular periodic acid Schiff staining by 48%, collagen I by 24%, and FN by 25%. The dramatic increases in transforming growth factor-β₁, plasminogen activator inhibitor-1, FN, and collagen I mRNAs seen in disease control animals compared with normal rats were all significantly reduced by ANG-(1–7) administration ( P < 0.05). These observations support our hypothesis that ANG-(1–7) has therapeutic potential for reversing glomerulosclerosis. Several results suggest ANG-(1–7) acts by counteracting ANG II effects: 1) renin expression in ANG-(1–7)-treated rats was dramatically increased as it is with ANG II blockade therapy; and 2) in vitro data indicate that ANG II-induced increases in mesangial cell proliferation and plasminogen activator inhibitor-1 overexpression are inhibited by ANG-(1–7) via its binding to a specific receptor known as Mas.