OXIDIZED LOW-DENSITY-LIPOPROTEIN IN EXPERIMENTAL FOCAL GLOMERULOSCLEROSIS

Oxidized low-density lipoproteins (Ox-LDL) have been shown to be involved in the pathogenesis of atherosclerosis. Because of the similarities between atherosclerosis and focal glomerulosclerosis, a study was performed to demonstrate whether Ox-LDL could be detected in the glomeruli in experimental FGS. FGS was induced in 12 rats on a 4% cholesterol-1% choline diet by seven injections of puromycin aminonucleoside over a 10 week period. Eight rats on a normal diet served as controls. Fourteen weeks after the start of the experiment all rats were sacrificed. The test animals showed marked hypercholesterolemia and proteinuria. About 20% of glomeruli in test animals showed FGS and variable amounts of glomerular lipid were demonstrated. Immunohistochemical staining using five specific monoclonal antibodies against various forms of Ox-LDL showed positive staining of a variable number of glomeruli in the test rats. The staining pattern appeared to be intracellular. Staining with ED1 showed significantly increased numbers of intraglomerular monocytes in the test rats (test vs. control 2.4 +/- 1.1 vs. 0.4 +/- 0.1 monocytes per glomerulus, P < 0.0001). Control animals showed no segmental sclerosis, no glomerular lipid, and no staining for Ox-LDL. Lipid analysis of isolated glomeruli showed increased cholesterol, increased arachidonic acid and decreased eicosapentaenoic acid in test animals compared to controls. The findings suggest a role for Ox-LDL in the pathogenesis of experimental FGS and support the hypothesis that FGS is analogous to atherosclerosis.