Oxidized lipid-mediated alterations in proteoglycan metabolism in cultured pulmonary endothelial cells

Compared to cholesterol or linoleic acid (18:2), oxidized lipids such as cholestan-3β,5,6β-triol (triol) and hydroperoxy linoleic acid (HPODE) markedly impair endothelial barrier function in culture [Hennig and Boissonneault, 1987; Hennig et al. 1986]. Because proteoglycans contribute to vascular permeability properties, the effects of cholesterol and 18:2 and their oxidation products, triol and HPODE, on endothelial proteoglycan metabolism were determined. While cholesterol was without effect, a concentration-dependent decrease in cellular proteoglycans (measured by ³⁵S incorporation) was observed after exposure to triol. Compared to control cultures, cholesterol reduced mRNA levels for the proteoglycans, perlecan and biglycan. Triol had a similar effect on biglycan but not on perlecan mRNA levels. Compared to 18:2, 1, 3 and 5 μM HPODE depressed cellular proteoglycans. Perlecan mRNA levels were reduced more by HPODE when compared to 18:2. Biglycan mRNA levels were reduced by 3 μM, but not by 5 μM HPODE. These data demonstrate that oxidized lipids such as triol and HPODE can decrease cellular proteoglycan metabolism in endothelial monolayers and alter mRNA levels of major specific proteoglycans in a concentration-dependent manner. This may have implications in lipid-mediated disruption of endothelial barrier function and atherosclerosis.