Fig. 2

Probiotic mechanisms in the gastrointestinal tract. Probiotics administration may manipulate gut microbial composition and reduce growth of pathogens and stimulate mucin secretion via stimulation of Goblet cells. Probiotic-mediated immunomodulation may occur through mediation of cytokine secretion through TLRs (ECs, DCs, and MQs), which can also affect proliferation and differentiation of immune cells (T-cells, CD cells, B cells) especially T-reg cells which resulted in an increase of IL-10 and TGF-β. Also, probiotics, through amplification of TJs, could improve gut permeability and also decrease entrance of LPS and pathogens from lumen into circulation. T-reg, regulatory T-cell; TLRs, toll-like receptors; ECs, endothelial cells; DCs, dendritic cells; MQs, macrophage cells; IL, interleukin; CD, cluster of differentiation; TGF-β, transforming growth factor beta; TNF-α, Tumor necrosis factor alpha; IFN-γ, Interferon gamma; TJPs, tight junction proteins; Ig, immunoglobulin g