Abstract 346: Mice Overexpressing Renin: a New Model of Progressive Chronic Kidney Disease

Abstract

Background: Hypertension-induced chronic kidney disease in mouse models is quite fast and consequently away from the human pathology. There is an increasing need for a mouse model that can be used to delineate the pathogenic process leading to progressive renal disease. Aim: Our objective was dual: to investigate whether mice overexpressing renin ectopically at constant and high levels by genetic clamping (RenTg) could mimic kinetics and the physiopathological characteristics of hypertension-induced CKD and to identify cellular and/or molecular events characterizing the different steps of the progression of CKD. Results: We found that RenTg mice are hypertensive (123±7 vs to 90±2 mm Hg for the wt age-matched animals, p<0.05) and slightly albuminuric (22.1±5.3 vs. 5.2±0.4 g/mol, p<0.01) as early as 3 month old. At this age, the expressions of adhesion markers such as vascular cell adhesion molecule-1 and platelet endothelial cell adhesion molecule-1 are 4-5 fold increased in the renal cortical vasculature indicating the beginning of endothelial dysfunction. Five month-old RenTg mice show perivascular and periglomerular infiltrations of macrophages and their GFR is starting to decrease(-10%). At 8 months, the renal cortex of RenTg mice is altered by leukocyte invasion, decreased expression of nephrin (a protein controlling filtration barrier), increased expression of KIM-1 (a protein typical of tubular cell stress) and of several pro-fibrotic agents of the TGFbeta family, and establishment of fibrotic lesions. At the age of 12 months, RenTg mice display several lesions of renal structure typical of hypertensive renal disease (such as glomerular ischemia, glomerulo- and nephroangio-sclerosis, mesangial expansion, tubular dilation), important proteinuria (138±20 g/mol) and a 55% fall of GFR. Conclusions: The RenTg strain develops progressively with age CKD. In this model, endothelial dysfunction is an early event preceding the structural and fibrotic alterations which ultimately lead to the development of CKD. This model can provide a useful tool allowing to gain new insights into the mechanisms of chronic renal failure and to identify new targets for arresting and/or reversing the development of CKD