Astragalus polysaccharide alleviates ulcerative colitis by regulating the balance of Tfh/Treg cells

The immunomodulatory function of natural active ingredients has long been a focus of scientific research, with recent hotspots reporting targeted modulation of the follicular helper T cells (Tfh)/regulatory T cells (Treg) balance as an emerging strategy for the treatment of ulcerative colitis (UC). Here, dextran sodium sulfate induced mice UC and Astragalus polysaccharide (APS, 200 mg/kg/day) was administered simultaneously. In this study, APS effectively alleviated colitis in mice by improving survival rate, disease activity index (DAI), the change rate of body weight, colonic length and weight, and histopathological injury of the colon. Moreover, APS regulated the expression of inflammatory cytokines interleukin (IL)-2, IL-6, IL-12p70, IL-23, Tumour necrosis factor (TNF)-ɑ, and transforming growth factor (TGF)-β1 in colonic tissues of colitis mice. Importantly, APS significantly downregulated Tfh cell and the expression of its related nuclear transcription factors Blimp-1 and Bcl-6, and cytokine IL-21. Meanwhile, APS regulated the differentiation of Tfh subpopulations in colitis mice, with Tfh10 and Tfr significantly upregulated while Tfh1, Tfh17, and Tfh21 significantly downregulated. In addition, APS significantly upregulated Treg cells and the levels of its associated nuclear transcription factor Foxp3, and cytokine IL-10 in colitis mice. In conclusion, APS effectively alleviated UC by reshaping the balance of Tfh/Treg cells.