A Nonpyroptotic IFN-γ–Triggered Cell Death Mechanism in Nonphagocytic Cells Promotes <i>Salmonella</i> Clearance In Vivo

Abstract

The cytokine IFN-γ has well-established antibacterial properties against the bacterium <i>Salmonella enterica</i> in phagocytes, but less is known about the effects of IFN-γ on <i>Salmonella</i>-infected nonphagocytic cells, such as intestinal epithelial cells (IECs) and fibroblasts. In this article, we show that exposing human and murine IECs and fibroblasts to IFN-γ following infection with <i>Salmonella</i> triggers a novel form of cell death that is neither pyroptosis nor any of the major known forms of programmed cell death. Cell death required IFN-γ-signaling via STAT1-IRF1-mediated induction of guanylate binding proteins and the presence of live <i>Salmonella</i> in the cytosol. In vivo, ablating IFN-γ signaling selectively in murine IECs led to higher bacterial burden in colon contents and increased inflammation in the intestine of infected mice. Together, these results demonstrate that IFN-γ signaling triggers release of <i>Salmonella</i> from the <i>Salmonella</i>-containing vacuole into the cytosol of infected nonphagocytic cells, resulting in a form of nonpyroptotic cell death that prevents bacterial spread in the gut.