TMAO promotes NLRP3 inflammasome activation via the ERS/NF-kb pathway in ox-LDL-induced THP-1 macrophages and accelerates the secretion of IL-1β、IL-18

Macrophages inflammation from variety of risk factors is critical in the rupture of atherosclerotic(AS) plaques. Trimethylamine oxide (TMAO), a dietary metabolite that depends on Gut microbiota, exerts strongly pro-inflammatory effects on Atherosclerosis. Nowadays, mounting research showed that NLRP3 inflammasome activation is essential for the pathogenesis of AS. The present study was to investigate the effect of TMAO on ox-LDL-induced NLRP3 inflammasomes activation of THP-1 cells, and to explore the potential mechanism. Used Cell Counting Kit-8 assay, LDH assay to evaluate the changes of macrophage activity under TMAO and ox-LDL, respectively, to clarify the appropriate dosage. Proteins related to NLRP3 inflammasomes, NF-kb and ERS were determined via Western Blot. Inflammatory cytokine secretion was then examined via ELISA. PCR detected gene levels of inflammatory markers, and caspase-1 activity assay was utilized to detect intracellular caspase-1 activity. The results showed that TMAO could activate NLRP3 inflammasome in ox-LDL-induced THP-1 macrophages and accelerate inflammatory factor release. In addition, TMAO can further activate the expression of ERS-related proteins( including BiP、p-PERK) and NF-KB pathway. NLRP3 inhibitor MCC950, NF-kb inhibitor JSH-23, and ER stress inhibitor 4-PBA reversed TMAO's promoting effect in ox-LDL-induced macrophage. Given these data, we conclude that TMAO promotes NLRP3 inflammasomes activation via the ERS/NF-kb pathway in ox-LDL induced THP-1 macrophages. Reducing the TMAO levels may be a viable approach to prevent atherosclerosis plaque development.