The effects of intestinal dendritic cells on the imbalance of mucosal Th1/Th2 immune response pathway and visceral hypersensitivity in IBS-D rats

To study the role of intestinal dendritic cells in the imbalance of local mucosal Th1/Th2 immune response pathway and its effect on visceral hypersensitivity in IBS-D rats through the synergy effects by CD4+Th cells and mast cells. Methods: 45 adult SD rats were randomly divided into a blank control group, model control group, and  model group,each group (n = 15). Rats in the model group were subjected to IBS visceral hypersensitive modeling by acetic acid enema combined with restraint stress. AWR test and fecal characteristics were used to evaluate the visceral sensitivity of rats. The expression of CD103, a surface molecule specific to dendritic cells in the colon tissue of the ileocecal region, was detected by immunohistochemistry. Flow separation technique was employed to isolate dendritic cells from mesenteric lymph nodes and CD4+T lymphocytes from spleen, and the dendritic cells were co-cultured with T lymphocytes in vitro. MTT assay was employed to detect the ability of dendritic cells to promote the proliferation of initial T lymphocytes. The cytokine levels of IL-12 and INF-γ secreted through Th1-pathway, and IL-4 and IL-9 secreted through Th2-pathway were determined by ELISA.Results: Compared with the blank control group and model control group, the number of CD103-labeled dendritic cells in the model group were significantly increased. Dendritic cells from intestinal lymph nodes developed enhanced ability to promote the proliferation of spleen CD4+Tcell, and secreted more IL-4 and IL-9 than that in the control group while the secretion of IL-12 was significantly reduced (P < 0.05).