S1751 Copy Number Variant and Extended SNP Genome Wide Association Study in Celiac Disease

Background and Aim: RNAi is a powerful biological tool whereby any specific genes of interest can be specifically targeted. However, application of RNAi for silencing genes of the GI tract has proven difficult. We recently described a bacteria-based RNAi technology (transkingdom RNAi, tkRNAi) to simultaneously produce and deliver RNAi to the GI tract (Xiang, Nat Biotech 2006, 697). The aim of this study was to examine whether tkRNAi can be used to silence the expression of IL-10, an anti-inflammatory cytokine, and induce a pro-inflammatory state In Vivo. Methods: After selection of themost powerful siRNA sequence, tkRNAi bacteria were created producing shRNA against mouse IL-10 (TRIP-sh7) and control (TRIP-scrambled). J774.A1 cells were incubated with TRIP-bearing bacteria for 2h at various MOIs, and then stimulated with LPS for 24h. IL-10 gene silencing was analyzed by quantitative RT-PCR and ELISA. To assess In Vivo gene silencing, 12 Balb/c mice were randomized into 3 groups: untreated (n=4); TRIP-sh7 (n=4); TRIP-scrambled (n=4). Following bacteria treatment for 2 weeks, colons were harvested and analyzed by qRT-PCR and IHC staining for IL-10 and γ-IFN. Results: treatment of J774.A1 cells with TRIP-sh7 reduced IL-10 mRNA and protein levels by >80% (p 70% (p < 0.05) compared to animals treated with TRIPscrambled control bacteria. IHC staining of colon tissue demonstrated a marked reduction of IL-10 protein expression in TRIP-sh7 treated mice compared to untreated or mice treated with control bacteria. Moreover, treatment with TRIP-sh7 was associated with increased colonic production of the TH1 cytokine γ-IFN. Treatment with TRIP-sh7 for two weeks was also associated with a significant loss of body weight compared to untreated or mice treated with control bacteria (p < 0.05 for both). Summary and Conclusion: bacteria expressing shRNA against IL-10 can mediate potent gene silencing in LPS-stimulated J774.A1 cells, and in colonic epithelial cells In Vivo. Furthermore colonic levels of γ-IFN were markedly increased following bacterial RNAi against IL-10. tkRNAi approach may be useful for In Vivo functional genomics studies in the GI tract, and for developing RNAi therapies for GI diseases. Since tkRNAi can be adapted to induce silencing in multiple animal species, this approach may be suited for development of animal models in rodents or non-rodent, for diseases such as IBD.