Sodium salicylate prevents inflammation-associated decreases in phosphorylated-Enos SER1177 in human aortic endothelial cells through an AMPK-dependent mechanism

Obesity is associated with chronic inflammation and increased risk of developing cardiovascular disease (CVD). Obesity is also associated with nitric oxide (NO)-mediated vascular endothelial dysfunction (VED), an independent predictor of increased CVD risk in humans. Pro-inflammatory cytokines secreted by the adipose tissue, such as TNF-Α, may contribute to VED through promotion of insulin resistance or directly through a reduction in endothelial NO synthase (eNOS) expression and/or phosphorylation. Sodium salicylate (Na-Sal) is a non-acetylated aspirin that inhibits the pro-inflammatory transcription factor nuclear factor-ΚB (NF-ΚB) and activates the cellular metabolism regulator AMP-activated protein kinase (AMPK). AMPK is a known activator of eNOS. We tested the hypothesis that Na-Sal increases eNOS expression/phosphorylation in TNFΑ-stimulated endothelial cells through an AMPK-dependent mechanism. Human aortic endothelial cells (HAECs) incubated in vitro with TNF-Α (10 ng/ml, 2 hrs) demonstrated decreased (vs. control) expression (via Western blotting) of eNOS^ser1177 phosphorylation (n=8; PThr172 phosphorylation (n=8, Pser1177 phosphorylation (vs. control, n=7; P=0.14) and AMPK^Thr172 phosphorylation (vs. control, n=9; P=0.42). The AMPK activator AICAR prevented eNOS^ser1177 phosphorylation down-regulation by TNF-Α in a manner similar to Na-Sal (n=2, P=0.839). Co-treatment with the AMPK inhibitor compound C (10 μM, 30 min) abolished the ability of Na-Sal to prevent down-regulation of eNOS^ser1177 phosphorylation by TNF-Α (vs. control, n=3; Pser1177 in endothelial cells in part through AMPK.