Safflower Polysaccharides Alleviate TNBS-Induced Colitis by Modulating Gut Immunity

This study aims to investigate the potential immunological mechanisms by which Safflower polysaccharides (SPSs) regulate colitis. The therapeutic effect of SPSs on colitis was investigated by trinitrobenzene sulfonic acid (TNBS)-induced rats model, TNF-α-stimulated Caco-2 cells, LPS-induced THP-1 cell model, and a co-culture model of Caco-2 and THP-1. The results demonstrated that SPSs effectively ameliorated clinical symptoms, reduced the expression of pro-inflammatory factors, restored colonic pathological damage, regulated the body’s immunity, and inhibited intestinal macrophage M1 polarization in vivo. In vitro, SPSs could alleviate the inflammatory response of epithelial cells, inhibit macrophage M1 polarization and regulate epithelial-immune cells interaction. Through the experimental study of siRNA-CHI3L1 and r-CHI3L1, it was found that CHI3L1 mediated the interaction between epithelial cells and immune cells. This study demonstrated that SPS can significantly improve clinical symptoms and alleviated colonic damage in TNBS-induced colitis rat models. The underlying mechanisms are associated with STAT3/NF-κB signaling and immunomodulation, where the immunoregulatory effect is based on CHI3L1-mediated epithelial-immune cell interaction mechanisms.