Glucosamine Hydrochloride and Tunicamycin Attenuate Palmitate‐Induced Glycosylation of Cyclooxygenase‐2 in Primary Human Vascular Smooth Muscle Cells

Abstract

Cyclooxygenase‐2 is a well‐studied mediator of inflammation in the vessel wall, expressed minimally in normal physiological conditions but inducible in pathophysiological conditions like atherosclerosis. Increases in COX‐2 transcription result in prostanoid production, such as prostaglandin E2 (PGE2). PGE2 acts through multiple EP receptors in the vasculature to cause vasoconstriction, vasodilation, change vascular permeability, and promote remodeling. Both COX‐2 expression and PGE2 production contribute to the formation of unstable plaques and increased risk for thrombotic events. Recent studies have shown that free fatty acids such as palmitic acid can act as pro‐inflammatory ligands, but their effect on COX‐2 and regulation of vascular function and health is not well elucidated. Thus, the objective of the study was to investigate changes in post‐translational modification of COX‐2 in response to stimulation via palmitate, as well as pharmacological inhibition and the effect on downstream prostanoid production. Human vascular smooth muscle cells (HVSMC) of brain, aortic and coronary artery origin were treated chronically (12 to 18 hr) with vehicle (5% BSA and 0.1% ethanol), palmitate, tunicamycin, or glucosamine. Protein levels were assessed via immunoblotting and prostanoid production was assessed via ELISA. Palmitate increased the expression of COX‐2 and its glycosylation state. Co‐treatment with the N‐linked glycosylation inhibitors tunicamycin and glucosamine attenuated the increase in glycosylation state induced by palmitate. Additionally, palmitate‐induced increases in PGE2 production were attenuated by co‐treatment with tunicamycin. In conclusion, the results suggest that the increase of vascular COX‐2 glycosylation by saturated fatty acids increases COX‐2 activity, an effect attenuated by inhibition of glycosylation. This regulation of COX‐2 activity via post‐translational modification in the vasculature is a possible novel mechanism that may contribute to the development of cardiovascular disease by diminishing the health of vascular tissue.Support or Funding InformationValley Research Partnership (RG, PR) and University of Arizona Sarver Heart Center (PR)