Figure 2.

Interactions between gut microbiota and the intestinal mucosal immunity. Intestinal microorganisms in the body can be classified into two main categories: probiotic and pathogenic bacteria. Pathogenic bacteria include: Salmonella spp, Staphylococcus aureus, Vibrio parahaemolyticus, Bacillus spp, Campylobacter jejuni; The probiotic bacteria in the body could stimulate the expression of α4β7 by T cells and B cells, then enter into the blood circulation; Bifidobacterium induce the expression of CD4⁺ T cells, increase the number of IgA by plasma cells, and release IL-10 by the induction of spleen cells and DC-CD4⁺ T cells; Lactobacillus could stimulate LPLs, thereby activating STAT3 signaling pathway and ISCs to enhance intestinal mucosal immunity; SCFAs produced by plasma cells could modulate the macrophages and dendritic cells to maintain the intestinal function; During SAP, the abundance of pathogenic bacteria increases and part of them could enter the body through the damaged tight junction; M cells play an important role in resistance to the pathogenic bacteria by targeting CGRP; Lactobacillus acidophilus combined with Bacillus subtilis can stimulate the production of CD4⁺T cells and SIgA⁺ cells, resulting in the increase in GPR43, GPR41, AhR and HIF-1α; The presence of Clostridium butyricum could enhance the Treg response and suppress the Th1 and Th17 response.