Abrogation of TGF‐beta Signaling in Dendritic Cells Leads to E‐cadherin‐mediated Adhesion between Dendritic Cells and Epithelium which Contributes to the Pathogenesis of Inflammatory Bowel Disease

Abstract

BACKGROUNDWe previously reported that a murine colitis model with dendritic cell (DC)‐ specific TGF‐beta signal deletion (CD11c‐Cre Tgfbr2fl/fl) showed Notch ligand overexpression on DCs and intestinal inflammation with goblet cell depletion. However, it has not been proved whether DC's Notch ligands are responsible for these phenotypes. Here, we establish a 3D co‐culture system of intestinal organoids with DCs to investigate the interactions between DCs and epithelium on the pathogenesis of inflammatory bowel disease (IBD), and examine therapeutic targets using this system.METHODSIn vivo, we used CD11c‐Cre Tgfbr2fl/fl mice, CD11c‐Cre Tgfbr2fl/fl Cdh1fl/fl mice and Cre‐negative mice as control. Intestinal lamina propria DCs (LPDCs) were isolated from CD11c‐Cre Tgfbr2fl/fl and control mice, and RNA extracted from these LPDCs was used for PCR array analysis of gene expressions related to adhesion molecules. We co‐cultured bone‐marrow‐ derived DCs (BMDCs) and intestinal organoids from CD11c‐Cre Tgfbr2fl/fl mice in Matrigel. A Notch inhibitor (DAPT), a Wnt inhibitor (C59), and neutralizing antibodies for Jagged1, CD103 and E‐cadherin were used for treatment.RESULTSq‐PCR array revealed LPDCs from colitic CD11c‐Cre Tgfbr2fl/fl mice had elevated expressions of many adhesion molecules, such as E‐cadherin, Integrin families, as well as Notch ligands. Oranoids co‐cultured with BMDCs from CD11c‐Cre Tgfbr2fl/fl mice changed their 3D budding structures into large cystic spheroids, but transwell‐separated BMDCs did not. Live cell imaging of organoid co‐culture system showed direct attachment of BMDCs on organoids. DAPT treatment in co‐culture retained budding structures, while C59 treatment did not. Then we evaluated the effect of neutralization of several DC surface molecules. Anti‐Jagged1 antibody or anti‐CD103 antibody did not prevent abnormal differentiation of BMDC‐co‐cultured organoids In contrast, anti‐E‐cadherin antibody significantly inhibited abnormal cyst formation. We also utilized BMDCs derived from CD11c‐Cre Tgfbr2fl/fl Cdh1fl/fl mice, which failed to induce cystic changes of organoids. In vivo, CD11c‐Cre Tgfbr2fl/fl Cdh1fl/fl mice showed attenuated colitis with sufficient goblet cells compared to CD11c‐Cre Tgfbr2fl/fl mice. Finally, we evaluated the therapeutic effect of anti‐E‐cadherin antibody on CD11c‐Cre Tgfbr2fl/fl mice, and found anti‐E‐cadherin treatment improved colitis of these mice.CONCLUSIONSAbrogation of TGF‐beta signaling in DCs upregulates E‐cadherin expression on DCs. Our data using 3D co‐culture system and IBD mouse model suggest blocking of E‐cadherin‐ mediated DCs and epithelial interactions may have therapeutic potential for IBD.Support or Funding InformationThis work was supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI Grant Numbers 23590933 and 17K15717, and Asahi Life Foundation.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.