Salsalate ameliorates the atherosclerotic response through HO-1- and SIRT1-mediated suppression of ER stress and inflammation

Inflammation plays a causative role in atherosclerosis development. Salsalate is an anti-inflammatory drug used to treat atherosclerosis, but the mechanisms by which it affects atherosclerotic progression remain unclear. Human umbilical vascular endothelial cells (HUVECs) and THP-1 human monocytes were treated with salsalate. Heme oxygenase 1 (HO-1) and sirtuin 1 (SIRT1) small interfering RNAs (siRNAs) were used to suppress each gene expression. Protein analyses were performed for measuring the expression of HO-1, SIRT1, nuclear factor kappa B (NFκB), cell adhesion molecules, and endoplasmic reticulum (ER) stress markers. Furthermore, cell adhesion assay, caspase 3 activity assay, and ELISA were also performed. In this study, we show that salsalate increases the expression of HO-1 and SIRT1 in HUVEC and suppresses lipopolysaccharide (LPS)-induced atherosclerotic responses via HO-1- and SIRT1-mediated pathways. Salsalate treatment of HUVEC and THP-1 cells reduced LPS-induced phosphorylation of NFκB and secretion of the proinflammatory cytokines TNFα and MCP-1. Salsalate treatment of HUVEC reduced the expression of the adhesion molecules ICAM, VCAM, and E-selectin and the LPS-induced adhesion of THP-1 cells to HUVEC. Salsalate treatment also attenuated LPS-induced ER stress and cell apoptosis. These anti-atherosclerotic effects were reversed by treating cells with siRNA for HO-1 and SIRT1. Salsalate ameliorates LPS-induced atherosclerotic reactions via HO-1 and SIRT1-dependent reduction of inflammation and ER stress. Activation of these pathways by salsalate may provide therapeutic strategies for treating atherosclerosis.