MiR-155 promotes macrophage pyroptosis induced by Porphyromonas gingivalis through regulating the NLRP3 inflammasome.

Abstract

The aim of this study is to detect pyroptosis in macrophages stimulated with Porphyromonas gingivalis and elucidate the mechanism by which P.gingivalis induces pyroptosis in macrophages. The immortalized human monocyte cell line U937 was stimulated with P.gingivalis W83. Flow cytometry was carried out to detect pyroptosis in macrophages. The expression of miR-155 was detected by real-time PCR and inhibited using RNAi. Suppressor of cytokine signaling (SOCS) 1, cleaved GSDMD, caspase (CAS)-1, caspase-11, apoptosis-associated speck-like protein (ASC), and NOD-like receptor protein 3 (NLRP3) were detected by Western blotting, and IL-1β and IL-18 were detected by ELISA. The rate of pyroptosis in macrophages and the expression of miR-155 increased upon stimulation with P.gingivalis and pyroptosis rate decreased when miR-155 was silenced. GSDMD-NT, CAS-11, CAS-1, ASC, NLRP3, IL-1β, and IL-18 levels increased, but SOCS1 decreased in U937 cells after stimulated with P.gingivalis. These changes were weakened in P.gingivalis-stimulated U937 macrophages transfected with lentiviruses carrying miR-155 shRNA compared to those transfected with non-targeting control sequence. However, there was no significant difference in ASC expression between P.gingivalis-stimulated shCont and shMiR-155 cells. Porphyromonas gingivalis promotes pyroptosis in macrophages during early infection. miR-155 is involved in this process through regulating the NLRP3 inflammasome.