M1776 Toll-Like Receptor 4 (TLR4) is a Target of Wnt/β-Catenin Signaling in Intestinal Epithelial Cells (IEC): Implications for Sporadic Colon Cancer

Abstract

whether colonic tissue-specific factors are responsible for re-educating DC into a gut-like phenotype. To address this issue we cultured human colonic biopsies from healthy controls and collected supernatants (SN) to condition human blood DC for 24 hours. RESULTS: Conditioning DC with SN generated In Vitro a human gut-like DC phenotype, characterized by a higher proportion of cells expressing the CCR9 (p=0.0017, n=11), β7 (p=0.0328, n=13) and CD103 (p=0.0354, n=10) gut-homingmarkers compared with their basal counterparts. A tolerogenic phenotype was also induced, characterized by reduced surface expression of the co-stimulatory markers CD40 (p=0.0297, n=9) and CD83 (p=0.0315, n=8), and also of TLR2 (p=0.0029, n=13) and TLR4 (p=0.0372, n=11). In addition, a regulatory intracellular DC cytokine profile was induced with reduced IL-12 and increased IL-10 production (n= 3). Furthermore, SN-conditioned DC demonstrated enhanced phagocytic properties (n=3), compared with those in basal conditions. These data demonstrate that human blood DC can be modulated to express the phenotype and function of human gut DC. Moreover, SNconditioned DC were less effective in stimulating proliferation of allogeneic T-cells, which subsequently expressed an increased gut/skin homing profile (n=3). CONCLUSION: We have demonstrated the relevance of the local tissue microenvironment in modulating DC since conditioning blood DC with colonic biopsy SN -through a mechanism in which vitamin A was revealed as essential but not sufficienthave the capacity to condition DC into gutlike DC with unique properties rendering them crucial for oral tolerance. Identifying all the molecules related to the generation of the tolerogenic gut-like DC would provide us with new targets for immunomodulation in patients suffering from IBD, where the functionality of gut-DC is altered leading to a lack of oral tolerance against the commensal microbiota.