Constitutive STAT5 activation regulates Paneth and Paneth-like cells to control <i>Clostridium difficile</i> colitis

Abstract

<i>Clostridium difficile</i> impairs Paneth cells, driving intestinal inflammation that exaggerates colitis. Besides secreting bactericidal products to restrain <i>C. difficile</i>, Paneth cells act as guardians that constitute a niche for intestinal epithelial stem cell (IESC) regeneration. However, how IESCs are sustained to specify Paneth-like cells as their niche remains unclear. Cytokine-JAK-STATs are required for IESC regeneration. We investigated how constitutive STAT5 activation (Ca-pYSTAT5) restricts IESC differentiation towards niche cells to restrain <i>C. difficile</i> infection. We generated inducible transgenic mice and organoids to determine the effects of Ca-pYSTAT5-induced IESC lineages on <i>C. difficile</i> colitis. We found that STAT5 absence reduced Paneth cells and predisposed mice to <i>C. difficile</i> ileocolitis. In contrast, Ca-pYSTAT5 enhanced Paneth cell lineage tracing and restricted Lgr5 IESC differentiation towards pYSTAT5⁺Lgr5^-CD24⁺Lyso⁺ or cKit⁺ niche cells, which imprinted Lgr5^hiKi67⁺ IESCs. Mechanistically, pYSTAT5 activated Wnt/β-catenin signaling to determine Paneth cell fate. In conclusion, Ca-pYSTAT5 gradients control niche differentiation. Lack of pYSTAT5 reduces the niche cells to sustain IESC regeneration and induces <i>C. difficile</i> ileocolitis. STAT5 may be a transcription factor that regulates Paneth cells to maintain niche regeneration.