Oxidized low-density lipoprotein-induced p62/SQSTM1 accumulation in THP-1-derived macrophages promotes IL-18 secretion and cell death.

Abstract

Macrophage autophagy has a protective role in the development of atherosclerosis; however, it turns dysfunctional in advanced lesions with an increase in p62/sequestosome-1 protein. Little is known about the role and significance of p62 accumulation in atherosclerosis. The present study investigated the association between p62 expression and the process of foam cell formation. Foam cell models were established through incubation of THP-1-derived macrophages with oxidized low-density lipoprotein, and the process of foam cell formation was detected by Oil red O staining. Furthermore, the dynamic change of p62 expression was detected by western blotting and quantitative polymerase chain reaction. Additionally, using gene silencing techniques, the roles of p62 in foam cells were investigated with ELISA, MTT and flow cytometry. The results indicated that besides serving as a marker of autophagy deficiency, the p62 protein could also mediate inflammation and cytotoxicity in advanced foam cells. Additionally, the implication of p62 in autophagy inhibition and foam cell formation makes it a key atherogenic factor under autophagy-deficient conditions.