P-128 Ven120, A Plant Derived Human Protein, Attenuates Murine Ileitis Through Activation of Treg Function

Abstract

Current hypotheses suggest that Crohns disease (CD) may develop through a dysregulated mucosal immune response toward the commensal enteric flora in genetically susceptible individuals. Multiple animal studies indicate that regulatory T cells (Treg) regulate the immune response in normal intestinal mucosa and thereby prevent colitis development. A breakdown of this tolerance to luminal antigens plays a pivotal role in IBD development. We hypothesize that a plant produced human milk protein, Ven120, can modulate the adaptive immune system in Crohn's disease to ameliorate inflammation. We aimed to validate this hypothesis using a TNF-driven model of CD the TNFDARE mouse model, in which a 69bp deletion of the AU-rich element confers increased TNF mRNA stability leading to spontaneous chronic murine ileitis. The Ven120 was provided by oral gavage or by subcutaneous Alzet pump to 10-12 week old TNFDARE mice with ileitis. After 2 weeks these mice were evaluated for intestinal permeability by FITC dextran flux, inflammation by histology, cell isolation and flow cytometry as well as Treg function. Finally, IL-10 and IL17 output was measured both by ELISA and by intracellular cytokine staining. Isolated CD4+CD25− T cells had decreased proliferation in the presence of Ven120. These cells produced increased quantities of IL-10. In the TNFDARE mouse model of IBD after 2 weeks of treatment with Ven120 versus vehicle there was a significant drop in influx of Naive CD44lowCD62Lhi T cells into the lamina propria of the intestine. In addition to this there was a significant increase in Treg numbers and these cells produced increased quantities of IL-10. Histology of the intestines from these mice was evaluated by a pathologist in blinded fashion and all indices of inflammation were improved. Similar studies were carried out in the DSS model of colitis and similar anti-inflammatory effects were noted. Our studies have effectively demonstrated the therapeutic potential of Ven120 in murine models of inflammatory bowel disease. Specifically, Ven120 administration significantly decreased naive T cell infiltration and proliferation in the intestinal lamina propria, mesenteric lymph nodes and spleen of 12 weeks old TNFDARE mice. An increase in CD4+Foxp3+ regulatory T cells was noted in the Ven120-treated mice. These Ven120 treated mice also exhibited improved histological indices and had improved intestinal barrier function, indicating efficacy for Ven120 to decrease inflammation in a preclinical model of CD.