P008 Modulation of Wnt signaling via a Wnt mimetic improved epithelial healing without causing hyperplasia in a mouse colitis model

Abstract Background Disruption of the colon epithelial barrier is a characteristic of ulcerative colitis (UC), allowing luminal microbes to come into contact with intestinal immune cells resulting in inflammation. All approved UC treatments are anti-inflammatory drugs and because they do not directly heal the epithelial barrier, the intestinal immune system continues to be exposed to gut microbes, resulting in low remission rates. Physiological Wnt signaling is fundamental to intestine epithelial homeostasis and renewal. Modulation of Wnt signaling might present an opportunity to achieve histological remission, which is associated with an improved clinical course, in UC. Previously, in vivo overexpression or administration of exogenous R-Spondin (RSPO), which amplifies Wnt signaling by increasing the amount of Wnt receptors on the cell surface, was reported to show effects on the intestine epithelium and helped regenerate intestine epithelium in various injury models. However, RSPO was also reported, to induce hyperplasia in normal intestine epithelium. Wnt signaling may also be modulated with recently developed Wnt mimetics which mimic endogenous Wnt proteins and activate downstream β-catenin signaling upon engaging with receptors of Wnts. The objective of the current study was to compare the effect of these two approaches in an acute DSS model. Methods Utilizing a mouse acute DSS colitis model, we compared the epithelial healing effects of a Surrozen proprietary Wnt mimetic, R2M3-26, RSPO2, and combination treatments of R2M3-26 and RSPO2. Animals received 4% (wt/vol) dextran sulfate sodium (DSS) in drinking water for 7 days followed by 1% DSS in drinking water from day 8. Protein treatments began on day 4. Disease activity, body weight (BW), fecal score, and occult blood were measured daily. Animals were terminated on day 10 for colon and small intestine histology as well as a serum cytokine panel. Results DSS damage to the colon epithelium was visible by H&E stain at day 4 and day 7 and continued to progress. We observed reduced mRNA expression of Wnt target genes and Wnt ligands in the colon, suggesting compromised Wnt signaling in the tissue. R2M3-26, RSPO2, and the combination treatments were efficacious in improving Disease Activity Index (DAI) and reducing serum cytokine levels. However, both RSPO treatments and combination treatments caused hyperproliferation of epithelium in the small intestine and the colon, consistent with what was reported in normal mice. Conclusion The Surrozen Wnt mimetic, R2M3-26, repaired the DSS damaged colon epithelium without causing hyperproliferation of epithelial cells in the intestine, making it a potential therapeutic platform for IBD.