Proteoglycans and endothelial barrier function: effect of linoleic acid exposure to porcine pulmonary artery endothelial cells

Certain fatty acids induce changes in endothelial barrier function which may be mediated by alterations in normal proteoglycan synthesis/metabolism. To test this hypothesis, pulmonary artery derived endothelial cells were treated with media supplemented with linoleic acid (18:2), and/or a known proteoglycan synthesis inhibitor, β-d-xyloside. Independent exposure to 1 MM β-d-xyloside or 90 μM 18:2 increased albumin transfer, i.e., decreased barrier function, when compared with control cultures. 18:2 and β-d-xyloside increased albumin transfer additively, suggesting that the mechanisms by which 18:2 and β-d-xyloside alter the proteoglycan metabolism are different. Compared with the control group, treatment with 18:2 inhibited proteoglycan synthesis, decreased anionic properties of heparan sulfate proteoglycans in the cell monolayers and caused the release of a unique chondroitin sulfate proteoglycan into the culture media. Treatment with β-d-xyloside caused an increased incorporation of radioactive sulfate into glycosaminoglycans but inhibited proteoglycan synthesis. These results suggest that the fatty acid- and β-d-xyloside-induced impairment in endothelial barrier function may involve changes in the synthesis, release and physicochemical properties of proteoglycans.