Effect of lipoproteins on cultured human mesangial cells

It was recently reported that low-density lipoprotein (LDL) promotes mesangial cell proliferation, and oxidized LDL is cytotoxic for mesangial cells, However, there have been few studies about the effects of other lipoproteins on mesangial cells, Accordingly, we investigated the effect of various lipoproteins on cultured human mesangial cells using H-3-thymidine (H-3-TdR) incorporation and cell counting assays, We also investigated the levels of several cytokines in mesangial cell culture supernatants after stimulation by the lipoproteins, Addition of very-low-density lipoprotein (VLDL) at concentrations up to 100 mu g/mL, intermediate-density lipoprotein (IDL) at up to 50 mu g/mL, and LDL at up to 50 mu g/mL induced the proliferation of cultured human mesangial cells, whereas cell growth was inhibited at higher concentrations, Oxidized LDL caused a concentration-dependent decrease of H-3-TdR incorporation, High-density lipoprotein (HDL) had no proliferative effect at any concentration, Exposure to VLDL, IDL, LDL, or a high concentration of HDL enhanced the secretion of interleukin-6, platelet-derived growth factor, and transforming growth factor-beta by mesangial cells, whereas tumor necrosis factor-alpha secretion was stimulated by oxidized LDL, These findings indicate that triglyceride (TG)-rich lipoproteins (VLDL and IDL) promote mesangial cell proliferation as well as LDL, whereas oxidized LDL has the reverse effect, These effects of lipoproteins may be related to modulation of various cytokines. Accordingly, TO-rich lipoproteins, LDL, and oxidized LDL may be involved in mesangial cell proliferation and injury in patients with mesangial proliferative glomerulonephritis. (C) 1997 by the National Kidney Foundation, Inc.