Background. Triglyceride (TG)-rich lipoproteins have been reported to promo
te atherosclerosis, but little is known about their role in kidney disease
or about their effects on mesangial cells. Accordingly, the purpose of this
study was to investigate which lipoproteins could influence mesangial cell
proliferation in vitro. We assessed the effect of various lipoproteins [ve
ry low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL),
low density lipoprotein (LDL), oxidized LDL, and high-density lipoprotein (
HDL)] on the proliferation of cultured human mesangial cells and also asses
sed the influence of these lipoproteins on cytokine production.
Methods. We investigated the effect of various lipoproteins on cultured hum
an mesangial cells using H-3-thymidine incorporation and cell counting assa
ys and investigated the levels of several cytokines [interleukin (IL)-6, pl
atelet-derived growth factor (PDGF), transforming growth factor (TGF)-beta,
and tumor necrosis factor-alpha] in mesangial cell culture supernatants af
ter stimulation by the lipoproteins.
Results. Not only LDL but also TG-rich lipoproteins (VLDL and IDL) promoted
the proliferation of mesangial cells up to certain concentrations, but cel
l growth was actually decreased at higher concentrations. Oxidized LDL caus
ed a concentration-dependent decrease of H-3-thymidine incorporation, and H
DL had no proliferative effect at any concentration. Exposure to VLDL, IDL,
LDL, or a high concentration of HDL enhanced the secretion of IL-6, PDGF-A
B, and TGF-beta by mesangial cells, whereas TNF-alpha secretion was stimula
ted by oxidized LDL.
Conclusions. TG-rich lipoproteins, LDL, and oxidized LDL may be involved in
mesangial cell proliferation and injury in patients with mesangial prolife
rative glomerulonephritis.