Figure 2.

Mechanism of action of probiotics. Direct mechanism: probiotics can activate sentinel cells through the Toll-like activation of signaling pathways; DCs can drive NK cell activation by secreting cytokines such as IL-12 and IL-15, and probiotics can impact this pathway; probiotics can cause B cells to differentiate into IgA-producing plasma cells; and probiotics also interact with antigen-presenting cells to influence the reduction of proinflammatory cytokines, thereby triggering an adaptive response. Indirect mechanism: Through the manipulation of the gut epithelial barrier and mucus layer properties, probiotic release of antimicrobial compounds, and management of competition with pathogenic bacteria, specific probiotic metabolites may exert anti-inflammatory and antibacterial effects. This figure was drawn by Figdraw.