β-catenin Signaling Drives Intestinal Epithelial Production of Interleukin-33

Background: Interleukin (IL)-33 is a key responder to intestinal infection, injury, and inflammation. It drives protective epithelial re-modeling via a stromal-epithelial circuit. However, we know little about the regulation of epithelial IL-33 at homeostasis and in disease. Our group previously found that colonic epithelial production of IL-33 is restrained by the inflammation-responsive signaling regulator, Sprouty2. Loss of Sprouty2 activates GSK3β (a key mediator of canonical Wnt/β-catenin signaling) and induces IL-33 in the colon, but the specific role of β-catenin and Wnt pathway components involved in this induction are unknown. Hypothesis: Canonical Wnt/β-catenin signaling induces colonic epithelial expression of IL-33. Methods: Bulk and single-cell RNAseq were performed on colons from mice with an intestinal epithelial-specific Sprouty2 deletion (Spry2 IEKO ) or littermate controls and subjected to gene enrichment and Panther pathway analyses. Colonic epithelial cell cultures were treated with Wnt3a and R-spondin to activate β-catenin signaling; small molecule inhibitors were used to inhibit CBP- or p300-mediated β-catenin signaling arms. IL-33 levels were assayed by qPCR and ELISA. Results: Analysis of significantly altered genes in Spry2 IEKO colons by Panther analysis found an enrichment in genes regulated by canonical Wnt signaling (FDR 3.72E-02), correlating with increased IL-33 observed in these mice. Analysis of single-cell RNAseq suggests colonic epithelial IL-33 is predominantly expressed in the stem and progenitor cell niche. Colonic epithelial cells treated with Wnt ligand showed a significant induction in IL-33 (p<0.05) at both RNA and protein levels. Inhibition of CBP-mediated but not p300-mediated β-catenin signaling prevented IL-33 induction, correlating with decreased expression of the CBP inhibitor, Psen1, in Spry2 IEKO colons. Conclusion: CBP-mediated β-catenin signaling promotes colonic epithelial expression of IL-33. Acute inflammation-mediated loss of Sprouty2 drives IL-33 induction in the stem cell niche as a protective response to injury or infection. NIH K01DK131390 (MS); Crohn's and Colitis Foundation CDA (MS); NIH R01DK135954 (CL); NIH R01DK119694 (MF). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.