Skip to main content
. 2023 Jan 2;12(1):184. doi: 10.3390/cells12010184

Figure 2.

Figure 2

Mechanisms of action of probiotic bacteria. Lactobacillus can (i) stimulate T cell regulatory cells (Treg cells) to produce TGF-β, interleukin-10 (IL-10), and IL-8, (ii) increase levels of secreted IL-6 secreted in a Toll-like receptor (TLR)-2-dependent manner, thereby inducing the clonal expansion of all IgA-producing B cells, while also stimulating the expression of macrophage mannose receptor CD206, (iii) inhibit the expression of Janus kinase (JAK) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) genes, (iv) increase the release of IL-12p70 and IL-4, (v) reduce the TLR expression and increase CD40 and CD80 expressions, (vi) degrade the proinflammatory chemokine IFN-γ-inducible protein 10 (IP-10), (vii) increase the expression of TLR-9, and (viii) favor the expression of nucleotide binding oligomeric domain-like receptor protein 3 (NLRP3), cysteine proteinase-1 (Caspase-1), and IL-18. Lacticaseibacillus and limocaseibacillus can induce β-defensins 2 and 4 and IL-8 expressions. Distinct studies reported opposing data on TLR expression. Bifidobacterium can (i) inhibit the expression JAK and NF-κB genes, (ii) favor the overexpression of IL-10 and TGF-β, while, at the same time, stimulate the production of IgAs, (iii) favor Treg cell differentiation, (iv) increase the total helper (CD4+) and activated (CD25+) T lymphocytes and NK cells, (v) reduce the expression of CD19 on B cells, (vi) induces the production of monocyte chemoattractant protein 1 (MCP-1) and TNF-α through TLR-9 stimulation, and (vii) increase the number of Foxp3(+) T regulatory cells and the release of CCL20, CCL22, CXCL10, and CXCL11. Escherichia coli can induce the expression of TLR-5 and TNF-α as well as increase the number of CD4+ cells. Bacteroidales stimulates the release of IL-6 accompanied by the expression of mucin-2 and claudin-1. Lactobacillus, lacticaseibacillus, limocaseibacillus, bifidobacterium, and streptococcus can favor the release of TNF-α, IL-6, IL-1β. Streptococcus can induce clonal expansion of B cells stimulated to release IgAs. Dash arrow: conflicting data have been reported on the effect of lactobacilli in increasing CD4+ T cell number.