PCSK9 deficiency reduces atherosclerosis, apolipoprotein B secretion, and endothelial dysfunction

• Published in: Journal of lipid research Vol. 59; no. 2; pp. 207 - 223
• Main Authors: Sun, Hua, Krauss, Ronald M., Chang, Jeffrey T., Teng, Ba-Bie
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.02.2018; Journal of Lipid Research; The American Society for Biochemistry and Molecular Biology; Elsevier
• Subjects: Animals; Apolipoprotein B; Apolipoproteins B - metabolism; Arteriosclerosis; Atherogenesis; Atherosclerosis; Atherosclerosis - metabolism; Autophagy; Clonal deletion; Endothelial cells; Endothelium, Vascular - metabolism; Inflammation; Intercellular adhesion molecule 1; Interleukin 6; Kexin; Lipoproteins (very low density); Liver - metabolism; Low density lipoprotein; LOX-1 protein; Mice; Mice, Inbred C57BL; Mice, Knockout; Monocyte chemoattractant protein 1; Phagocytosis; Phospholipids; Plasma levels; Proprotein Convertase 9 - deficiency; Proprotein Convertase 9 - metabolism; proprotein convertase subtilisin/kexin type 9; Proprotein convertases; Subtilisin; TLR2 protein; Toll-like receptors; TRAF6 protein; proprotein convertase subtilisin/kexin type 9; low density lipoprotein; autophagy
• ISSN: 0022-2275; 1539-7262; 1539-7262
• DOI: 10.1194/jlr.M078360

Proprotein convertase subtilisin/kexin type 9 (PCSK9) interacts directly with cytoplasmic apoB and prevents its degradation via the autophagosome/lysosome pathway. This process affects VLDL and LDL production and influences atherogenesis. Here, we investigated the molecular machinery by which PCSK9 modulates autophagy and affects atherogenesis. We backcrossed Pcsk9−/− mice with atherosclerosis-prone Ldlr−/−Apobec1−/− (LDb) mice to generate Ldlr−/−Apobec1−/−Pcsk9−/− (LTp) mice. Deletion of PCSK9 resulted in decreased hepatic apoB secretion, increased autophagic flux, and decreased plasma levels of IDL and LDL particles. The LDLs from LTp mice (LTp-LDLs) were less atherogenic and contained less cholesteryl ester and phospholipids than LDb-LDLs. Moreover LTp-LDLs induced lower endothelial expression of the genes encoding TLR2, Lox-1, ICAM-1, CCL2, CCL7, IL-6, IL-1β, Beclin-1, p62, and TRAF6. Collectively, these effects were associated with substantially less atherosclerosis development (>4-fold) in LTp mice. The absence of PCSK9 in LDb mice results in decreased lipid and apoB levels, fewer atherogenic LDLs, and marked reduction of atherosclerosis. The effect on atherogenesis may be mediated in part by the effects of modified LDLs on endothelial cell receptors and proinflammatory and autophagy molecules. These findings suggest that there may be clinical benefits of PCSK9 inhibition due to mechanisms unrelated to increased LDL receptor activity.