15-Deoxy-Δ12,14-Prostaglandin J2 Reinforces the Anti-Inflammatory Capacity of Endothelial Cells With a Genetically Determined NO Deficit

Abstract

Rationale: Fluid shear stress (FSS) maintains NOS-3 (endothelial NO synthase) expression. Homozygosity for the C variant of the T-786C single-nucleotide polymorphism of the NOS3 gene, which solely exists in humans, renders the gene less sensitive to FSS, resulting in a reduced endothelial cell (EC) capacity to generate NO. Decreased bioavailability of NO in the arterial vessel wall facilitates atherosclerosis. Consequently, individuals homozygous for the C variant have an increased risk for coronary heart disease (CHD).

Objective: At least 2 compensatory mechanisms seem to minimize the deleterious effects of this single-nucleotide polymorphism in affected individuals, one of which is characterized herein.

Methods and results: Human genotyped umbilical vein ECs and THP-1 monocytes were used to investigate the role of 15-deoxy-Δ12,14-prostaglandin J₂ (15d-PGJ₂) in vitro. Its concentration in plasma samples from genotyped patients with CHD and age-matched CHD-free controls was determined using quantitative ultraperformance LC-MS/MS. Exposure of human ECs to FSS effectively reduced monocyte transmigration particularly through monolayers of CC-genotype ECs. Primarily in CC-genotype ECs, FSS elicited a marked rise in COX (cyclooxygenase)-2 and L-PGDS (lipocalin-type prostaglandin D synthase) expression, which appeared to be NO sensitive, and provoked a significant release of 15d-PGJ₂ over baseline. Exogenous 15d-PGJ₂ significantly reduced monocyte transmigration and exerted a pronounced anti-inflammatory effect on the transmigrated monocytes by downregulating, for example, transcription of the IL (interleukin)-1β gene (IL1B). Reporter gene analyses verified that this effect is due to binding of Nrf2 (nuclear factor [erythroid-derived 2]-like 2) to 2 AREs (antioxidant response elements) in the proximal IL1B promoter. In patients with CHD, 15d-PGJ₂ plasma levels were significantly upregulated compared with age-matched CHD-free controls, suggesting that this powerful anti-inflammatory prostanoid is part of an endogenous defence mechanism to counteract CHD.

Conclusions: Despite a reduced capacity to form NO, CC-genotype ECs maintain a robust anti-inflammatory phenotype through an enhanced FSS-dependent release of 15d-PGJ₂.

Keywords: coronary heart disease; endothelial cells; humans; nitric oxide synthase; polymorphism, single nucleotide.