Chitinase-3-like protein 1 ameliorates atherosclerotic responses via PPARδ-mediated suppression of inflammation and ER stress.

Chitinase 3-like protein 1 (CHI3L1) is a novel biomarker of systemic inflammation. However, the effects of CHI3L1 on the progression of atherosclerosis remain to be explored. In the current study, we found that CHI3L1 induces peroxisome proliferator-activated receptor delta (PPARδ) expression, leading to a dose-dependent increase in oxygen-regulated protein 150 (ORP150) expression. We demonstrated that CHI3L1 suppresses atherosclerotic reactions caused by LPS treatment via a PPARδ-dependent pathway. Treatment of HUVECs and THP-1 cells with CHI3L1 suppressed LPS-induced phosphorylation of nuclear factor kappa B (NFκB) and secretion of proinflammatory cytokines such as TNFα and MCP-1. In HUVECs, expression of adhesion molecules and LPS-stimulated adhesion of THP-1 cells to the endothelium were significantly reduced after CHI3L1 treatment. Furthermore, LPS-induced endoplasmic reticulum (ER) stress and cell apoptosis were significantly ameliorated after treatment of HUVECs with CHI3L1. Particularly, all of the pro-atherosclerotic effects were significantly mitigated by treatment with small interfering (si) RNA for PPARδ. In conclusion, CHI3L1 ameliorates LPS-induced atherosclerotic reactions via PPARδ-mediated suppression of inflammation and ER stress.