Necroptosis mediators RIPK3 and MLKL suppress intracellular Listeria replication independently of host cell killing

RIPK3, a key mediator of necroptosis, has been implicated in the host defense against viral infection primary in immune cells. However, gene expression analysis revealed that RIPK3 is abundantly expressed not only in immune organs but also in the gastrointestinal tract, particularly in the small intestine. We found that orally inoculated , a bacterial foodborne pathogen, efficiently spread and caused systemic infection in -deficient mice while almost no dissemination was observed in wild-type mice. infection activated the RIPK3-MLKL pathway in cultured cells, which resulted in suppression of intracellular replication of Surprisingly, infection-induced phosphorylation of MLKL did not result in host cell killing. We found that MLKL directly binds to and inhibits their replication in the cytosol. Our findings have revealed a novel functional role of the RIPK3-MLKL pathway in nonimmune cell-derived host defense against invasion, which is mediated through cell death-independent mechanisms.