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Background and aims Proprotein convertase subtilisin/kexin 9 (PCSK9) has emerged as a popular target in the development of new cholesterol-lowering drugs and therapeutic interventions for atherosclerosis. PCSK9 could accelerate atherosclerosis through mechanisms beyond the degradation of the hepatic low-density lipoprotein receptor. Several clinical studies suggested that PCSK9 is involved in atherosclerotic inflammation. Accordingly, this study aimed to explore the role of PCSK9 in vascular inflammation that promotes atherosclerotic progression. Methods We examined whether PCSK9 silencing via transduction with the lentivirus-mediated PCSK9 shRNA (LV-PCSK9 shRNA) vector affects the formation of vascular lesions in hyperlipidemia-induced atherosclerosis in apolipoprotein E knockout (apoE KO) mice. In vitro , the effects of PCSK9 on oxLDL-induced macrophages inflammation were investigate using LV-PCSK9 and LV-PCSK9 shRNA for PCSK9 overexpression and PCSK9 silencing. Results Immunohistochemical analysis showed that PCSK9 expression increased within atherosclerotic plaques in apoE KO mice. These in vivo results showed that the LV-PCSK9 shRNA group of mice developed less aortic atherosclerotic plaques compared with the control group. These lesions also had the reduced number of macrophages and decreased expression of vascular inflammation regulators, such as tumor necrosis factor-α, interleukin 1 beta, monocyte chemoattractant protein-1, toll-like receptor 4 and nuclear factor kappa B (NF-κB). We further showed that PCSK9 overexpression in macrophages in vitro increased the secretion of oxLDL-induced proinflammatory cytokines. PCSK9 overexpression upregulated TLR4 expression and increased p-IκBα levels, IkBα degradation, and NF-κB nuclear translocation in macrophages, but PCSK9 knockdown had the opposite effects in oxLDL-treated macrophages. Conclusions PCSK9 gene interference could suppress atherosclerosis directly through decreasing vascular inflammation and inhibiting the TLR4/NF-κB signaling pathway without affecting plasma cholesterol level in high-fat diet-fed apoE KO mice. PCSK9 may be an inflammatory mediator in the pathogenesis of atherosclerosis. [ABSTRACT FROM AUTHOR]

Atherosclerosis is an arterial disease associated with inflammation. Hence, the discovery of novel therapeutic agents for suppressing inflammatory responses is urgent and vital for the treatment of atherosclerosis in cardiovascular diseases. The total saponins of Aralia elata (Miq.) Seem. (TAS) are the main components extracted from the Chinese traditional herb Longya Aralia chinensis L., a folk medicine used in Asian countries for treating numerous diseases, enhancing energy and boosting immunity. However, the protective effects of TAS against inflammation-triggered vascular endothelial dysfunction, a critical early event during the course of atherosclerosis, and the potential mechanisms of this protection have been not demonstrated. Accordingly, the aim of this study was to investigate the anti-inflammatory and anti-apoptotic effects and the protective mechanisms of TAS, and show how TAS ameliorates human umbilical vein endothelial cell (HUVEC) damage caused by tumour necrosis factor-α (TNF-α). The results indicated that TAS exerted cytoprotective effects by inhibiting TNF-α-triggered HUVEC apoptosis, mitochondrial membrane potential depolarisation, and the regulation of inflammatory factors (IL-6, MCP-1, and VCAM-1) while suppressing NF-κB transcription. Furthermore, this phenomenon was related to activation of the phosphoinositide 3-kinase (PI3K)/Akt signalling pathway. Blocking the Akt pathway with LY294002, a PI3K inhibitor, reversed the cytoprotective effect of TAS against TNF-α-induced endothelial cell death. Moreover, LY294002 partially abolished the effects of TAS on the upregulation of the Bcl-2 family of proteins and the downregulation of Bax protein expression. In conclusion, the results of our study suggest that TAS suppresses the inflammation and apoptosis of HUVECs induced by TNF-α and that PI3K/Akt signalling plays a key role in promoting cell survival and anti-inflammatory reactions during this process. [ABSTRACT FROM AUTHOR]