PERK/NF-κb pathway mediates TMAO aggravating the activation of NLRP3 inflammasome in ox-LDL -induced THP-1cells

Abstract

Background: By associated with inflammation intraplaque, Trimethylamine N-oxide (TMAO) increase the risk of atherosclerotic plaque rupture and has been identified as the independent predictor of cardiovascular events. However, the underlying mechanism is yet unclarity. Accumulating studies have established the critical role of NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome in mediating intraplaque inflammation and plaque progression. Here, we discussed the role of NLRP3 inflammasome in aggravating ox-LDL-induced macrophage inflammation response to TMAO and its potential mechanism. Results: Our results showed that TMAO enhanced ox-LDL-induced inflammation in THP-1cells. Adding to TMAO remarkably upregulated the expression or mRNA level of NLRP3, Cysteinyl aspartate specific proteinase 1(caspase-1) p20 and Apoptosis associated speck-like protein containing CARD(ASC) and enhanced the activity of caspase-1. An NLRP3 inhibitor (MCC950) reversed the promoting effect of NLRP3 inflammasome activation by TMAO and subsequently macrophage inflammation. Significantly, TMAO also boosted the activation of endoplasmic reticulum stress (ERS) and nuclear factor-kappa B (NF-kB) pathway in ox-LDL-induced cells, manifested as the increasing expression of p-NF-κB, Bip and phosphorylated protein kinase R-like ER kinase (p-PERK). Activation of the NLRP3 inflammasome by TMAO was reversed by the ERS inhibitor 4-PBA or the NF-κB phosphorylation inhibitor JSH-23. Meanwhile, 4-PBA further inhibited the NF-κB phosphorylation and alleviated the NLRP3 inflammasome activation. Conclusions: We concluded that TMAO exacerbates ox-LDL-induced NLRP3 inflammasomes activation and subsequently interleukin (IL)-18 and IL-1b release in THP-1 macrophages, which partly regulated by the activating of the PERK/NF-κB signaling pathway.