Gastric Lgr5+ cells are programmed by Rspo3 to shield the gland from infection

R-spondin (Rspo) signaling is crucial for stem cell renewal and tissue homeostasis in the gastrointestinal tract. In the stomach, Rspo is secreted from myofibroblasts and controls epithelial gland regeneration by inducing proliferation of Wnt-responsive Axin2+ cells in the isthmus of the gland. Infection with H. pylori results in increased expression of stromal Rspo, leading to an expansion of Axin2+ isthmus stem cells and gland hyperplasia. Lgr5+ cells in the gland base are exposed to Rspo3 but the effects of this are not well understood. Here we demonstrate that apart from its activity as a mitogen, endogenous Rspo3 regulates gene expression of Lgr5+ cells in the gastric gland base. Surprisingly, Rspo3 induces differentiation within the Lgr5+ compartment towards secretory deep mucous cells. Moreover, the Rspo3-Lgr5 axis turns out to be a stimulus of epithelial antimicrobial defense. Infection with H. pylori induces a strong antimicrobial response, with Lgr5+ cells expressing antimicrobial compounds that are secreted into the lumen in an Rspo3-dependent manner. Depletion of Lgr5+ cells or knockout of Rspo3 in myofibroblasts leads to hyper-colonization of gastric glands, including the stem cell compartment, whereas systemic application of recombinant Rspo clears H. pylori from the glands. We provide an intriguing, unexpected feature of the Rspo3-Lgr5 axis in the stomach, exhibiting antimicrobial self-protection of the gland to protect the stem cell compartment from invading pathogens. Overall design: Lgr5eGFP reporter mice were infected with H. pylori for 2 months, uninfected mice served as controls. Mice were sacrificed and isolated, sorted Lgr5eGFP+ cells from the stomach antrum were used for single cell RNAseq using the 10x genome platform.

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Sigal M, Reinés MDM, Müllerke S, Fischer C, Kapalczynska M, Berger H, Bakker ERM, Mollenkopf HJ, Rothenberg ME, Wiedenmann B, Sauer S, Meyer TF