Figure 2.

The defense mechanism of FCGBP in mucosal diseases of the colon. (A) After entering the intestinal dense mucosa, bacterial compounds bind to Toll-like receptors, activating the NF-κB signaling pathway and promoting further mucus release. (B) After microorganisms, such as parasites, are detected by DCs or macrophages, their antigens are presented to T cells where they induce cytokines such as IL-13 and other cytokines secretion, promoting FCGBP production. (C) After FCGBP interacts with an IgG antigen complex, it is transported across the mucosa and is recognized by macrophages. (D) FCGBP-TFF3 complexes bind to bacteria to prevent them from passing through the epithelial barrier. IL, interleukin; FCGBP, IgGFc-binding protein; MUC2, mucin-2; TFF, trefoil factor family; TLRs, Toll-like receptors.