Robust colonic epithelial regeneration and amelioration of colitis via FZD-specific activation of Wnt signaling

Background and aims: Current management of inflammatory bowel disease (IBD) leaves a clear unmet need to treat the severe epithelial damage. Modulation of Wnt signaling might present an opportunity to achieve histological remission and mucosal healing when treating IBD. Exogenous R-spondin (RSPO), which amplifies Wnt signals by maintaining cell surface expression of Frizzled (FZD) and low-density lipoprotein receptor-related protein (LRP) receptors, helps repair intestine epithelial damage, but it also induces hyperplasia of normal epithelium. Wnt signaling may also be modulated with the recently developed Wnt mimetics, recombinant antibody-based molecules mimicking endogenous Wnts. Methods: We first compared the epithelial healing effects of RSPO2 and a Wnt mimetic with broad Fzd-specificity in an acute Dextran Sodium Sulfate (DSS) mouse colitis model. Guided by Fzd expression patterns in the colon epithelium, we also examined the effects of Wnt mimetics with sub-family Fzd-specificities. Results: In the DSS model, Wnt mimetics repaired damaged colon epithelium and reduced disease activity and inflammation and had no apparent effect on uninjured tissue. We further identified that the FZD5/8 and LRP6 receptor-specific Wnt mimetic, SZN-1326-p, was associated with the robust repair effect. Through a range of approaches including single-cell transcriptome analyses, we demonstrated that SZN-1326-p directly impacted epithelial cells, driving transient expansion of stem and progenitor cells, promoting differentiation of epithelial cells, histologically restoring the damaged epithelium and, secondarily to epithelial repair, reducing inflammation. Conclusion: It is feasible for treating epithelial damage in IBD to design Wnt mimetics such as SZN-1326-p that affect damaged intestine epithelium specifically and restore its physiological functions. Overall design: Mouse total colon cells from uninjured and the DSS colitis model were isolated by tissue dissociation and FACS purification prior to scRNA-seq using 10x Genomics reagents (v3). There were four uninjured replicates and three anti-GFP control treatments and three Surrozen protein (SZN-1326-p) treated samples per timepoints (24-hours and 48-hours after dosing).