Epithelial barrier disruption is a major cause of inflammatory bowel disease (IBD); however, the cellular and molecular regulation of intestinal epithelial homeostasis remains largely undefined. Here, we show that the C-type lectin receptor LSECtin (Clec4g) on macrophages is required for protection against dextran sulfate sodium-induced colitis. Mechanistically, LSECtin promotes apoptotic cell clearance by macrophages and induces the production of antiinflammatory/tissue repair factors in an engulfment-dependent manner, which in turn stimulates epithelial cell proliferation. Deletion of LSECtin results in defective engulfment by colon macrophages, leading to aberrant proresolving factor production and impaired intestinal epithelium repair. Collectively, our findings suggest that LSECtin-dependent corpse clearance by macrophages can direct intestinal regeneration and maintenance of the mucosal barrier after injury.

This study aimed to explore the effect of cell division cycle protein 42 (CDC42) on inflammatory response and immune response in mice bearing inflammatory bowel disease (IBD). Trinitrobenzene sulfonic acid was injected into the colon of mice to establish IBD model. The mice were divided into four groups (n ¼ 4): control, model, Ad5, and Ad5-CDC42. After establishing IBD model, mice which were treated with AD5 empty vector and AD5-CDC42 expression vector served as the Ad5 group and Ad5-CDC42 group, respectively. The mRNA and protein levels of interleukin 10 (IL-10), interferon-c (IFN-c), IL-4, and tumor necrosis factor-a (TNF-a) in the colon tissues were evaluated by RT-PCR and western blot, respectively. Their levels in the serum and colon tissues were examined by ELISA assay and immunohistochemical analysis, respectively. Their changes in the mRNA and protein levels were consistent and similar changes in the colon tissues and the serum were found among various groups. The levels of IL-10, IFN-c, IL-4, and TNF-a were lowest in the control group. Their levels in the model group and the Ad5 group were similar (p > .05) and significantly higher than those in the control group (p < .05).In comparison with the model group and the Ad5 group, their levels were significantly reduced in the Ad5-CDC42 group (p < .05). In conclusion, the levels of inflammatory cytokines were elevated in the colon tissues and serum of IBD mice, which could be reduced by the CDC42 treatment. CDC42 regulated the inflammatory response and the innate immune response in IBD mice. ARTICLE HISTORY

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The imbalance between effector CD4+ T helper 17 (Th17) and regulatory CD4+ T cells (Treg) cells and their associated cytokines, have been associated with the pathogenesis of inflammatory bowel disease (IBD). Total glycosides of paeony (TGP) is an alternative immunomodulatory agent that is widely used for the treatment of autoimmune diseases. The present study aimed to evaluate the modulatory effect of TGP in a rat model of colitis induced by 2,4,6‑trinitrobenzene sulfonic acid (TNBS). TGP was administered intragastrically 24 h after the TNBS intrarectal instillation for 7 days. TGP treatment ameliorated the clinical status and reversed the histopathologic severity of acute TNBS colitis. Furthermore, TGP inhibited the levels of Th17‑associated cytokines interleukin (IL)‑17, IL‑6, tumor necrosis factor‑α, whereas the expression levels of Treg‑associated cytokines IL‑10, transforming growth factor‑β in the plasma, colon, spleen and mesenteric lymph nodes (MLN). Additionally, TGP reduced the percentage of Th17 cells; however, the proportion of Treg cells in the spleen and MLN was increased. The present study also observed a suppression of Th17‑associated transcription factor, termed retinoid‑related orphan receptor‑γt (ROR‑γt). However, expression of the Treg‑associated transcription factor forkhead boxp3 was increased in the TGP treatment group. Therefore, the present findings suggest that TGP has a regulatory role in modulating the balance of Th17 and Treg cells to ameliorate the TNBS‑induced colitis and support the strategy of using TGP to treat IBD.