PCSK9 promotes atherosclerosis progression through the FOXO3a autophagy signaling pathway

The proprotein convertase subtilisin/kexin type 9 (PCSK9) has an impact on atherosclerosis by modulating the autophagy pathway; however, its precise mechanisms underlying autophagy require additional investigation.

ApoE-/- male mice were fed high-fat diets, different doses of COS (Chitosan oligosaccharide) or JY2 were given by gavage, and RAPA or CQ was injected intraperitoneally. The immunofluorescence intensities of PCSK9, FOXO3a and LC3, collagen fibers and calcium salt deposition in aortic sinus tissues were measured. In vitro, macrophages were pretreated with oe/siPCSK9, COS, RAPA, CQ or JY2 combined with ox-LDL, and autophagy-related protein levels, autophagic flux and autophagy-related genes were detected. COS significantly reduced PCSK9 expression in Raw264.7 cells and autophagy-related protein expression, slowing the progression of atherosclerotic plaques, as shown by reduced plaque area, lipid deposition, and calcium salt deposition and increased collagen fibers. In macrophages derived from atherosclerotic plaques, the concentrations of PCSK9 and FOXO3a were markedly elevated in the RAPA group compared to the ND group. In vitro studies revealed that PCSK9 enhances the expression of Beclin1, P62, LC3, and FOXO3a, while also augmenting autophagic flux, thereby promoting ox-LDL-induced autophagic injury in macrophages, whereas COS inhibited the formation of PCSK9, thereby inhibiting autophagic injury. In addition, the FOXO3a inhibitor JY2 significantly inhibited autophagy but did not significantly affect PCSK9. In addition, oe/siPCSK9 affected the extent and flow of autophagy in macrophages. COS and CQ also limit PCSK9 in ApoE-/- mouse atherosclerosis progression and in macrophages subjected to autophagy.

PCSK9 promotes macrophage autophagy injury and facilitates atherosclerosis progression through activation of the FOXO3a autophagy pathway, whereas COS reduces PCSK9 injury to macrophages and atherosclerosis. These findings provide a theoretical basis and experimental foundation for the future development of PCSK9 inhibitors as a new strategy for the treatment of As.