mPGES-1 (Microsomal Prostaglandin E Synthase-1) Mediates Vascular Dysfunction in Hypertension Through Oxidative...

mPGES-1 (microsomal prostaglandin E synthase-1), the downstream enzyme responsible for PGE₂ (prostaglandin E₂) synthesis in inflammatory conditions and oxidative stress are increased in vessels from hypertensive animals. We evaluated the role of mPGES-1-derived PGE₂ in the vascular dysfunction and remodeling in hypertension and the possible contribution of oxidative stress. We used human peripheral blood mononuclear cells from asymptomatic patients, arteries from untreated and Ang II (angiotensin II)-infused mPGES-1^-/- and mPGES-1^+/+ mice, and vascular smooth muscle cells exposed to PGE₂ In human cells, we found a positive correlation between mPGES-1 mRNA and carotid intima-media thickness (r=0.637; P<0.001) and with NADPH oxidase-dependent superoxide production (r=0.417; P<0.001). In Ang II-infused mice, mPGES-1 deletion prevented all of the following: (1) the augmented wall:lumen ratio, vascular stiffness, and altered elastin structure; (2) the increased gene expression of profibrotic and proinflammatory markers; (3) the increased vasoconstrictor responses and endothelial dysfunction; (4) the increased NADPH oxidase activity and the diminished mitochondrial membrane potential; and (5) the increased reactive oxygen species generation and reduced NO bioavailability. In vascular smooth muscle cells or aortic segments, PGE₂ increased NADPH oxidase expression and activity and reduced mitochondrial membrane potential, effects that were abolished by antagonists of the PGE₂ receptors (EP), EP1 and EP3, and by JNK (c-Jun N-terminal kinase) and ERK1/2 (extracellular-signal-regulated kinases 1/2) inhibition. Deletion of mPGES-1 augmented vascular production of PGI₂ suggesting rediversion of the accumulated PGH₂ substrate. In conclusion, mPGES-1-derived PGE₂ is involved in vascular remodeling, stiffness, and endothelial dysfunction in hypertension likely through an increase of oxidative stress produced by NADPH oxidase and mitochondria.