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P085 Expression profiling of Wnt pathway genes in colon biopsies of patients with Ulcerative Colitis

Lu, C.(1);Shah, D.(1);Wijnands, A.(2);Oldenburg, B.(2);Yeh, W.C.(3);Vanhove, G.(4);Li, Y.(1);

(1)Surrozen Inc., Discovery Biology, South San Francisco, United States;(2)University Medical Center Utrecht, Division Internal Medicine and Dermatology - Department Gastroenterology and hepatology, Utrecht, The Netherlands;(3)Surrozen Inc., In vivo pharmacology, South San Francisco, United States;(4)Surrozen Inc., Clinical Development, South San Francisco, United States

Background

There is an increasing demand of agents that can promote mucosal healing in Inflammatory Bowel Disease (IBD). Wnt/β-catenin signaling plays a critical role in epithelial regeneration and repair, and stimulating regeneration in the damaged epithelium by modulating Wnt signaling has been suggested as a potential treatment option for IBD. To guide development of Wnt modulating therapeutic molecules for IBD, an understanding of how Wnt signaling may be altered in IBD tissues is required. While earlier work showed altered Wnt pathway gene expression in UC tissues, these studies failed to consider disease conditions (moderate vs severe) and patient treatment history on expression of the Wnt family genes. These previous studies utilized RT-qPCR or microarray and did not reveal how Wnt pathway gene expression might be affected specifically in the epithelium and in the adjacent stromal stem cell niche. Here we report our work investigating expression patterns of Wnt pathway genes in UC biopsies from 12 patients with moderate and severe disease. Patients had either received no anti-TNF treatment or had gone through anti-TNF treatment and partially responded to the treatment.

Methods

Expression of a set of Wnt pathway genes was assessed in UC colon and rectum biopsies by RNAscope in situ hybridization and compared to expression patterns in normal control colon. The genes included the Wnt target genes AXIN2, LGR5 and RNF43, Wnt ligands and the FZD5 and LRP6 receptors enriched in the intestinal epithelium as well as key Wnt signal modulators RSPO1-4.

Results

Expression of Wnt target genes were mildly reduced in the UC colon epithelium, while their expression in some crypts appeared much lower. Overall expression levels of Wnt pathway genes did not differ between moderate and severe UC colon and Wnt target gene expression was more affected in the anti-TNF treated colons, which may reflect more refractory disease. Expression of FZD5, LRP6 and the key niche factor RSPO2, was reduced in the UC colon. RSPOs are normally expressed in the stromal cells next to the crypt bottom stem cell compartment but this expression pattern was disrupted in the UC colon as a result of immune cell infiltration. Although expression of Wnts was induced in the UC colon tissues, the location of expression was altered due to tissue damage, potentially making the Wnts less accessible to the intestinal stem cells.

Conclusion

Reduced expression of Wnt receptors, RSPOs and Wnt target genes indicate insufficient Wnt signal induction in the damaged colon epithelium of UC patients. This suggests that repair of the damaged epithelium by Wnt agonist treatment may constitute a new mechanism of action and benefit patients with UC.

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