Statins Attenuate Activation of the NLRP3 Inflammasome by Oxidized LDL or TNFα in Vascular Endothelial Cells through a PXR-Dependent Mechanism

Excessive activation of the NLRP3 inflammasome is implicated in cardiovascular diseases. Statins exert an anti-inflammatory effect independent of their cholesterol-lowering effect. This study investigated the potential role of statins in the activation of the NLRP3 inflammasome in endothelial cells (ECs). Western blotting and quantitative reverse-transcription polymerase chain reaction showed that oxidized low-density lipoprotein (ox-LDL) or tumor necrosis factor alpha (TNF alpha) activated the NLRP3 inflammasome in ECs. Simvastatin or mevastatin significantly suppressed the effects of ox-LDL or TNF alpha. Promoter reporter assays and small interfering RNA knockdown revealed that statins inhibit ox-LDL-mediated NLRP3 inflammasome activation via the pregnane X receptor (PXR). In addition, PXR agonists (rifampicin and SR12813) or overexpression of a constitutively active PXR markedly suppressed the NLRP3 inflammasome activation. Conversely, PXR knockdown abrogated the suppressive effect of rifampicin on NLRP3 inflammasome activation. Knockdown of lectin-like ox-LDL receptor or overexpression of I kappa B alpha-attenuated ox-LDL-or TNF alpha-triggered activation of the NLRP3 inflammasome. Chromatin immunoprecipitation assays indicated that mevastatin inhibited nuclear factor-kappa B binding to the promoter regions of the human NLRP3 gene. Collectively, these results demonstrate that the statin activation of PXR inhibits the activation of NLRP3 inflammasome in response to atherogenic stimuli such as ox-LDL and TNF alpha in ECs, providing a new mechanism for the cardiovascular benefit of statins.