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Deep crypt secretory cell differentiation in the colonic epithelium is regulated by Sprouty2 and interleukin-13.

Open AccessPublished:November 18, 2022DOI:https://doi.org/10.1016/j.jcmgh.2022.11.004
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      Abstract:

      Background & Aims

      Deep crypt secretory (DCS) cells are a critical component of the colonic stem cell niche. However, the regulatory mechanisms controlling DCS cell numbers and function are not well understood. Sprouty2 is an inflammation-responsive regulator of intracellular signaling that influences colonic secretory cell numbers in colitis via an epithelial-stromal IL-33/IL-13 signaling loop. Here we tested the hypothesis that IL-13, induced by epithelial Sprouty2 downregulation, promotes DCS cell differentiation and function.

      Methods

      Distal colons from mice with an intestinal epithelial-specific Sprouty2 deletion (Spry2ΔIE) and littermate controls were analyzed by in situ hybridization for Reg4+ DCS cells. Single cell RNA sequencing and immunostaining were used to identify DCS cell-derived host defense peptides (HDPs) and localization of IL-13 and IL-13 receptor; bulk RNA sequencing and qPCR were used to quantify changes in expression of identified HDPs. Cytokine treated colonoids were assessed for DCS cells. A requirement for an IL-33/IL-13 signaling loop in the regulation of DCS cells was assessed in vivo using IL-13 null mice.

      Results

      Reg4+ DCS cell numbers were increased 2-fold in distal colons of Spry2ΔIE mice with a concomitant overall increase in DCS cell marker expression (Reg4, Spink4, and Agr2). Single cell transcriptomics showed the HDP Retnlb/RELMβ is highly enriched in DCS cells. Retnlb/RELMβ expression was increased in Spry2ΔIE colons. IL-13, but not IL-33, induced Reg4 and Retnlb expression in colonic epithelial organoids, and IL-33-mediated expansion of the DCS cell population in vivo was dependent on IL-13, which was predominantly expressed by type II innate lymphoid cells (ILC2s) in the colonic mucosa.

      Conclusions

      Sprouty2 limits colonic DCS cell differentiation through suppression of IL-13 signaling. At homeostasis, DCS cells are marked by high levels of the HDP RELMβ. Loss of epithelial Sprouty2 activates ILC2s to release IL-13, promoting expansion of the DCS cell population and increased colonic RELMβ levels.

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