Suppression of NLRP3 inflammasome by a small molecule targeting CK1α-β-catenin-NF-κB and CK1α-NRF2-mitochondrial OXPHOS pathways during mycobacterial infection.

INTRODUCTION: Pyroptosis is an important inflammatory form of cell death and Mycobacterium tuberculosis (M.tb) chronic infection triggers excessive inflammatory pyroptosis of macrophages. Our previous research has confirmed that a small compound pyrvinium pamoate (PP) could inhibit inflammatory pathological changes and mycobacterial burden in M.tb-infected mice, but the potential mechanism of PP for inhibiting M.tb-induced inflammation remains unexplored. METHODS: The effects of PP on the NLRP3-ASC-Casp1 inflammasome assembly and activation, gasdermin D (GSDMD) mediated pyroptosis and inflammatory cytokines expression were assessed in human THP-1-derived macrophages after M.tb H37Rv/H37Ra/ Salmonella typhimurium (S. typhimurium) infection or LPS treatment by Transcriptome sequencing, RT-qPCR, Co-immunoprecipitation and Western Blot (WB) analysis. The lactate dehydrogenase (LDH) release assay was used to evaluate the CC50 of PP in M.tb-infected THP-1 cells. RESULTS: We found that M.tb/S. typhimurium infection and LPS treatment significantly activate NLRP3-ASC-Casp1 inflammasome activation, GSDMD-mediated pyroptosis and inflammatory cytokines (IL-1β and IL-18) expression in macrophages, whereas PP could suppress these inflammatory effects in a dose dependent manner. Regarding the PP-inhibition mechanism, we further found that this inhibitory activity is mediated through the PP-targeting casein kinase 1A1 (CK1α)-β-catenin-NF-κB pathway and CK1α-NRF2-mitochondrial oxidative phosphorylation (OXPHOS) pathway. In addition, a CK1α specific inhibitor D4476 or CK1α siRNA could reverse these inhibitory effects of PP on bacteria-induced inflammatory responses in macrophages. CONCLUSIONS: This study reveals a previously unreported mechanism that pyrvinium can inhibit NLRP3 inflammasome and GSDMD-IL-1β inflammatory pyroptosis via targeting suppressing CK1α-β-catenin-NF-κB and CK1α-NRF2-mitochondrial OXPHOS pathways, suggesting that pyrvinium pamoate holds great promise as a host directed therapy (HDT) drug for mycobacterial-induced excessive inflammatory response.