Microsomal Prostaglandin E Synthase-1-Derived PGE2 Inhibits Vascular Smooth Muscle Cell Calcification

Objective Chronic administration of selective cyclooxygenase-2 (COX-2) inhibitors leads to an increased risk of adverse cardiovascular events, including myocardial infarction and stroke. Vascular smooth muscle cell (VSMC) calcification, a common complication of chronic kidney disease, is directly related to cardiovascular morbidity and mortality. Here, we tested whether specific COX-2 inhibition affects vascular calcification during chronic renal failure. Approach and Results The COX-2-specific inhibitors NS398 and SC236 significantly increased high-phosphate (Pi)-induced VSMC calcification. Similarly, COX-2(-/-) VSMCs, COX-2(-/-) aortas rings treated with high Pi and adenine diet-induced COX-2(-/-) chronic renal failure mice displayed enhanced calcium deposition. Metabolomic analysis revealed the differential suppression of PGE(2) production by COX-1- and COX-2-specific inhibitors in high-Pi-stimulated VSMCs, indicating the involvement of PGE(2) during COX-2 inhibition-aggravated vascular calcification. Indeed, exogenous PGE(2) reduced alkaline phosphatase activity, osteogenic transdifferentiation, apoptosis, and calcification of VSMCs. In accordance, downregulation of microsomal prostaglandin E synthase (mPGES)-1 in VSMCs, mPGES-1(-/-) aorta with high-Pi stimulation and mPGES-1(-/-) chronic renal failure mice resulted in enhanced vascular mineralization. Further applications of RNAi and specific antagonists for PGE(2) receptors indicated EP4 may mediate PGE(2)-inhibited vascular calcification. Conclusions Our data revealed the pivotal role of COX-2-mPGES-1-PGE(2) axis in vascular calcification. The selective inhibition of COX-2 or mPGES-1 may increase the risk of calcification and subsequent adverse cardiovascular events during chronic renal failure.