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

Abstract 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.