A Novel Gastric Spheroid Co-culture Model Reveals Chemokine-Dependent Recruitment of Human Dendritic Cells to the Gastric Epithelium.

Gastric dendritic cells (DCs) control the adaptive response to infection with Helicobacter pylori, a major risk factor for peptic ulcer disease and gastric cancer. We hypothesize that DC interactions with the gastric epithelium position gastric DCs for uptake of luminal H pylori and promote DC responses to epithelial-derived mediators. The aim of this study was to determine whether the gastric epithelium actively recruits DCs using a novel co-culture model of human gastric epithelial spheroids and monocyte-derived DCs. Spheroid cultures of primary gastric epithelial cells were infected with H pylori by microinjection. Co-cultures were established by adding human monocyte-derived DCs to the spheroid cultures and were analyzed for DC recruitment and antigen uptake by confocal microscopy. Protein array, gene expression polymerase chain reaction array, and chemotaxis assays were used to identify epithelial-derived chemotactic factors that attract DCs. Data from the co-culture model were confirmed using human gastric tissue samples. Human monocyte-derived DCs co-cultured with gastric spheroids spontaneously migrated to the gastric epithelium, established tight interactions with the epithelial cells, and phagocytosed luminally applied H pylori. DC recruitment was increased upon H pylori infection of the spheroids and involved the activity of multiple chemokines including CXCL1, CXCL16, CXCL17, and CCL20. Enhanced chemokine expression and DC recruitment to the gastric epithelium also was observed in H pylori-infected human gastric tissue samples. Our results indicate that the gastric epithelium actively recruits DCs for immunosurveillance and pathogen sampling through chemokine-dependent mechanisms, with increased recruitment upon active H pylori infection.

Sebrell TA ，Hashimi M ，Sidar B ，Wilkinson RA ，Kirpotina L ，Quinn MT ，Malkoç Z ，Taylor PJ ，Wilking JN ，Bimczok D ... -  《Cellular and Molecular Gastroenterology and Hepatology》

CD103 (αE Integrin) Undergoes Endosomal Trafficking in Human Dendritic Cells, but Does Not Mediate Epithelial Adhesion.

Swain S ，Roe MM ，Sebrell TA ，Sidar B ，Dankoff J ，VanAusdol R ，Smythies LE ，Smith PD ，Bimczok D ... -  《Frontiers in Immunology》

Involvement of myeloid dendritic cells in the development of gastric secondary lymphoid follicles in Helicobacter pylori-infected neonatally thymectomized BALB/c mice.

Nishi T ，Okazaki K ，Kawasaki K ，Fukui T ，Tamaki H ，Matsuura M ，Asada M ，Watanabe T ，Uchida K ，Watanabe N ，Nakase H ，Ohana M ，Hiai H ，Chiba T ... -  《-》

Evidence for transepithelial dendritic cells in human H. pylori active gastritis.

Necchi V ，Manca R ，Ricci V ，Solcia E ... -  《-》

Helicobacter pylori immune escape is mediated by dendritic cell-induced Treg skewing and Th17 suppression in mice.

Helicobacter pylori infection increases gastric regulatory T cell (Treg) response, which may contribute to H pylori immune escape. We hypothesize that H pylori directs Treg skewing by way of dendritic cells (DCs) and thus inhibits interleukin-17(+) helper T cells (Th17) immunity. Two-photon microscopy was used to locate DCs in gastric lamina propria of mice. The induction of Th17 and Treg responses by bacteria-pulsed murine bone marrow-derived DCs was analyzed by cytokine production and stimulation of T-cell proliferation. The effect of VacA, CagA, transforming growth factor-beta (TGF-beta), and IL-10 on Th17/Treg balance was assessed. The in vivo significance of Tregs on the H pylori-specific Th17 response and H pylori density was determined by using anti-CD25 neutralizing antibodies to deplete Tregs in mice. We showed that mucosal CD11c(+) DCs are located near the surface of normal gastric epithelium, and their number increased after H pylori infection. Study of the direct interaction of DCs with H pylori showed a Treg-skewed response. The Treg skewing was independent of H pylori VacA and CagA and dependent on TGF-beta and IL-10. In vivo Treg skewing by adoptive transfer of H pylori-pulsed DCs reduces the ratio of gastric IL-17/Foxp3 mRNA expressions. The depletion of CD25(+) Tregs results in early reduction of H pylori density, which is correlated with enhanced peripheral H pylori-specific Th17, but not Th1, response. Overall, our study indicates that H pylori alters the DC-polarized Th17/Treg balance toward a Treg-biased response, which suppresses the effective induction of H pylori-specific Th17 immunity.

Kao JY ，Zhang M ，Miller MJ ，Mills JC ，Wang B ，Liu M ，Eaton KA ，Zou W ，Berndt BE ，Cole TS ，Takeuchi T ，Owyang SY ，Luther J ... -  《-》