Staphylococcus aureus induces ifn‐β production via a carma3‐independent mechanism

Abstract

Type I interferon (IFN) induction is a critical component of innate immune response to viral and bacterial infection, including S. aureus, but whether it activates the signaling in macro-phages and the regulation mechanisms is less well understood. Here we show that S. aureus infection promoted the IFN‐β mRNA expression and stimulator of IFN genes (STING)/TANK‐binding kinase 1 (TBK1)/ interferon regulatory factor 3 (IRF3)‐dependent production of IFN‐β. Infection with S. aureus induced caspase recruitment domain and membrane‐associated guanylate kinase‐like domain protein 3 (CARMA3) expression at both the mRNA and protein levels. The heat‐killed bacteria failed to trigger IRF3 phosphorylation and upregulation of CARMA3 expression. However, over-expression of CARMA3 did not affect phosphorylation of TBK1 or IRF3 in RAW264.7 cells, J774A.1 macrophages, and mouse embryonic fibroblast (MEF) cells. In conclusion, S. aureus infection induces STING/TBK1/IRF3‐mediated IFN‐β production in a CARMA3‐independent manner.