M300 series as IL-6Ra/ Claudin-2/ MIP3a as specific tkRNA/shRNAs against IBD. We evaluated live attenuated bacterial delivery of shRNAs against selected IBD gene targets to achieve specificity, efficacy, and safety. The in vitro efficacy was assessed by an invasion assay using the CMT-93 mouse colon epithelial cells (or RAW264.7 macrophages for TNF-a) and qRT-PCR measurement of mRNA reduction vs. b-actin control. Three gene targets (IL-6Ra, Claudin-2, and MIP3a) and two tkRNAi delivery strains were tested in vivo using an oxazolone or dextran sulfate sodium (DSS) acute murine colitis model. Oral delivery of IL-6Ra tkRNAi strains (CEQ608 and CEQ609) led to a significant reduction in colon length and abolished IL-6Rα message in proximal ileum in DSS exposed groups. Claudin-2 strains (CEQ621 and CEQ626) caused a significant reduction in Claudin-2 mRNA expression and protein levels in the colon as well as attenuation of the disease phenotype and enhanced survival. Treatment with MIP3a therapeutic strains CEQ631 and CEQ632 also resulted in a significant reduction in sum pathology scores and reduction in MIP3a mRNA expression. These findings suggest that tkRNAi-mediated gene silencing of pro-inflammatory targets represents a potential therapeutic development avenue for IBD therapy.