Table_4_Effects of three different probiotics of Tibetan sheep origin and their complex probiotics on intestinal damage, immunity, and immune signaling pathways of mice infected with Clostridium perfringens type C.XLSX

Tibetan sheep have unique intestinal microorganisms in their intestines that are adapted to the highland alpine and anoxic environment. To further clarify the probiotic properties of Tibetan sheep-derived probiotics, we selected three Tibetan sheep-derived probiotic isolates (Enterococcus faecalis EF1-mh, Bacillus subtilis BS1-ql, and Lactobacillus sakei LS-ql) to investigate the protective mechanisms of monocultures and their complex strains against Clostridium perfringens type C infection in mice. We established a model of C. perfringens type C infection and used histology and molecular biology to analyze the effects and mechanisms of different probiotic treatments on mice after C. perfringens type C infection. After supplementation with either probiotics or complex probiotics, mice were improved in terms of weight reduction and reduced the levels of cytokines in serum and increased the levels of intestinal sIgA, and supplementation with complex probiotics was effective. In addition, both probiotic and complex probiotic supplementation effectively improved the damage of intestinal mucosa and spleen tissue. The relative expressions of Muc 2, Claudin-1, and Occludin genes were increased in the ileum. The three probiotics and the compound probiotics treatment significantly reduced the relative mRNA expression of toll-like/MyD88/NF-κB/MAPK. The effect of probiotic treatment was similar to the results of engramycin treatment, but the effect of engramycin treatment on intestinal sIgA was not significant. Our results clarify the immunomodulatory effects of the three probiotic isolates and the complex probiotics on C. perfringens infection, and the repair of the intestinal mucosal barrier.

藏绵羊肠道内存在适配高原高寒缺氧环境的特有肠道微生物群落。为进一步明确藏源益生菌的益生特性，本研究选取3株藏绵羊来源的益生菌分离株：粪肠球菌(Enterococcus faecalis) EF1-mh、枯草芽孢杆菌(Bacillus subtilis) BS1-ql以及清酒乳杆菌(Lactobacillus sakei) LS-ql，旨在探究单一菌株及其复合菌株对小鼠C型产气荚膜梭菌(Clostridium perfringens type C)感染的保护机制。本研究构建了C型产气荚膜梭菌(Clostridium perfringens type C)感染小鼠模型，并通过组织学与分子生物学手段，分析不同益生菌干预对感染后小鼠的作用效果及调控机制。相较于感染模型组，单一益生菌或复合益生菌干预组小鼠的体重下降情况得到显著缓解，血清细胞因子水平降低，肠道分泌型免疫球蛋白A(secretory immunoglobulin A, sIgA)水平升高，其中复合益生菌的干预效果更为突出。此外，单一益生菌与复合益生菌干预均有效改善了肠黏膜与脾脏组织的病理损伤。回肠组织中黏蛋白2(Mucin 2, MUC2)、紧密连接蛋白-1(Claudin-1)以及闭合蛋白(Occludin)的基因相对表达量均显著上调。3株单一益生菌及复合益生菌干预均显著下调了Toll样受体(Toll-like receptor)/髓系分化因子88(Myeloid differentiation factor 88, MyD88)/核因子κB(Nuclear factor kappa-B, NF-κB)/丝裂原活化蛋白激酶(Mitogen-activated protein kinase, MAPK)信号通路的相对mRNA表达水平。单一益生菌干预的效果与恩拉霉素(Enramycin)干预相近，但恩拉霉素对肠道sIgA水平的调节效果并不显著。本研究结果明确了3株益生菌分离株及复合益生菌对C型产气荚膜梭菌(Clostridium perfringens type C)感染的免疫调节作用，以及其对肠黏膜屏障的修复功效。