Abstract 132: Glomerular Podocyte Damage is Mitigated by Normal HDL and ApoA1

Abstract

We and others have shown that chronic kidney disease (CKD) disrupts the normally beneficial effects of apoAI/HDL on many different cell types. Proteinuria which characterizes CKD is a hallmark of glomerular podocyte injury and a powerful risk factor for cardiovascular disease (CVD). Although the glomerular filtration barrier normally limits direct contact of lipoproteins with podocytes, disruption in the filtration barrier promotes such interactions. We therefore investigated the effects of normal HDL and ApoAI on injured podocytes and compared these effects to HDL isolated from subjects with CKD. Primary podocytes were isolated from wild type mice. The cells were exposed to puromycin (PAN, 100ug/ml) with and without HDL isolated from controls with normal kidney function, individuals with CKD, normal ApoA1 (EMD Millipore Company), and ApoA-I mimetic peptide L-4F. We assessed podocyte viability and proliferation (colorimetrically), cellular production of superoxide (ROS)(HPLC), membrane lipid rafts, phosphorylated caveolin-1 (Cav-1)(western blot). PAN significantly altered ROS production, cell viability, proliferation. ApoA1 or HDL Cont , but not HDL CKD , significantly improved each of these responses. In addition, L-4F increased podocyte viability (0.60±0.04 PAN vs 0.65±0.04 PAN+L-4F) and HDL Cont , but not HDL CKD , normalized the significant increase in PAN-induced Cav-1 phosphorylation (0.65±0.04 vs 0.81±0.05 vs 0.70±0.09, respectively). We conclude that podocyte damage including ROS production, cellular membrane and functions can be mitigated by normal HDL or its primary lipoprotein, ApoA1, findings that parallel beneficial functions of HDL/ApoA1 on other cell types. By contrast, HDL of subjects with CKD do not provide similar benefit.