Fig. 3
From: Mechanisms of probiotic Bacillus against enteric bacterial infections
Probiotic Bacillus produces various metabolites to activate intestinal immune. Metabolites trigger B cells and T cells through M cell (1) and dendritic cell (2), as well as improve the phagocytosis ability of macrophages (3) resulting in enhanced clearance of pathogens; and stimulate the intestinal associated lymphoid tissue to produce CD8+ and T cell (4), alleviate some kinds of inflammation. In another aspect, the metabolites improve the diversity of commensal microbiota (5), induce paneth cell producing AMPs (6) as well as enhance the expression of tight junction protein in epithelial cell (7), to strengthen the local barriers configuration