Atherosclerosis is a chronic disease comprising intima malfunction and arterial inflammation. Recent studies have demonstrated that autophagy could inhibit inflammatory response in atherosclerosis and exert subsequent atheroprotective effects. Our previous study also demonstrated the role of autophagy in the inhibition of inflammation by atorvastatin in vitro. Therefore, in the present study, we aimed to determine whether atorvastatin could upregulate autophagy to inhibit inflammatory cytokines secretion, lipid accumulation, and improve vulnerable plaque stability, both in vitro and in vivo. First, we established a vulnerable atherosclerotic plaque mouse model through partial ligation of left common carotid artery and left renal artery to explore the effect of atorvastatin on vulnerable plaques. The results showed that atorvastatin could enhance the stability of vulnerable atherosclerotic plaques and reduce the lesion area in the aorta. Atorvastatin could also inhibit NLRP3 inflammasome activation and inflammatory cytokines, such as IL-1β, TNF-α, and IL-18 secretion in vivo. Atorvastatin treatment upregulated the expression of autophagy-related protein microtubule-associated protein light chain (LC3B) and downregulated the expression of SQSTM1/p62, which suggested that autophagy was activated in vulnerable plaques. Transmission electron microscopy further demonstrated the atorvastatin-induced increase in autophagy activity in vulnerable atherosclerotic plaques. We employed oxidized low-density lipoprotein (ox-LDL) to stimulate RAW264.7 cells with atorvastatin, which showed that atorvastatin could attenuate lipid deposition, ameliorate inflammation, inhibit NLRP3 inflammasome activation, and enhance autophagy in vitro. All these beneficial effects were abolished by 3-methyladenine treatment, an autophagy inhibitor. Atorvastatin also significantly inhibited the phosphorylation of mTOR, which strongly suggested the involvement of the mTOR pathway. Our study proposed a new role for atorvastatin as an autophagy inducer to exert anti-inflammatory and atheroprotective effects, to stabilize vulnerable atherosclerotic plaques.

Macrophages play crucial roles in immune response and atherosclerosis-related cardiovascular disease. Recent evidence of macrophage autophagy has demonstrated a novel pathway through which contributes to vascular inflammation. The aim of this study was to elucidate the role of autophagy in the inhibition of inflammatory response in macrophages by atorvastatin. We found that atorvastatin promoted autophagy flow determined by up-regulating the expression of autophagy-related protein microtubule-associated protein light chain (LC3B), inducing the formation of autophagosomes and down-regulating the expression of SQSTM1/P62, which is consumed during autophagy. Atorvastatin also inhibited the expression of inflammatory factors IL-1β and TNFα induced by LPS in RAW264.7 cells. Furthermore, pretreatment with an autophagy inhibitor 3MA or LY294002 attenuated the suppressive effect of atorvastatin on LPS-induced IL-1β and TNFα expression. Additionally, knockdown autophagy-related gene 5(Atg5) with a special siRNA also prevented the role of atorvastatin in decreasing IL-1β and TNFα release induced by LPS. Finally, we detected that AKT/mTOR/P70S6K signaling pathway was involved in atorvastatin-induced autophagy in macrophages. These data suggest that atorvastatin attenuates LPS-induced inflammatory factors secretion, at least in part, through enhancing autophagy by AKT/mTOR signaling pathway. Our findings provide a novel evidence that statins exert anti-inflammatory effect in atherosclerosis by autophagy activation.

The vulnerable plaque is a key distinguishing feature of atherosclerotic lesions that can cause acute atherothrombotic vascular disease. This study was designed to explore the effect of autophagy on mitochondria‐mediated macrophage apoptosis and vulnerable plaques. Here, we generated the mouse model of vulnerable carotid plaque in ApoE−/− mice. Application of ApoE−/− mice with rapamycin (an autophagy inducer) inhibited necrotic core formation in vulnerable plaques by decreasing macrophage apoptosis. However, 3‐methyladenine (an autophagy inhibitor) promoted plaque vulnerability through deteriorating these indexes. To further explore the mechanism of autophagy on macrophage apoptosis, we used macrophage apoptosis model in vitro and found that 7‐ketocholesterol (7‐KC, one of the primary oxysterols in oxLDL) caused macrophage apoptosis with concomitant impairment of mitochondria, characterized by the impairment of mitochondrial ultrastructure, cytochrome c release, mitochondrial potential dissipation, mitochondrial fragmentation, excessive ROS generation and both caspase‐9 and caspase‐3 activation. Interestingly, such mitochondrial apoptotic responses were ameliorated by autophagy activator, but exacerbated by autophagy inhibitor. Finally, we found that MAPK‐NF‐κB signalling pathway was involved in autophagy modulation of 7‐KC–induced macrophage apoptosis. So, we provide strong evidence for the potential therapeutic benefit of macrophage autophagy in regulating mitochondria‐mediated apoptosis and inhibiting necrotic core formation in vulnerable plaques.