Figure 3.

Modulation of intestinal mucous immune function by SCFAs produced by probiotics and prebiotics (by figdraw). Probiotics and intestinal microorganisms metabolize dietary fibers, such as prebiotics, to produce SCFAs, which pass through the intestinal epithelial layer into the mucous layer and modulate the function of innate immune cells. For instance, SCFAs can activate monocytes and dendritic cells to enhance their phagocytosis and secretion, promote the differentiation of T-lymphocytes to regulatory T cells and helper T cells, and promote the proliferation and differentiation of B-lymphocytes. In addition, SCFAs can bind to GPCRs and mediate the transcription and translation of cytokines (e.g., IL-12) through activating pathways such as JAK/STAT, NF-κB, and MAPK. On the other hand, SCFAs also act as inhibitors of HDACs to enhance the expression of immune factors.