Table 2.

Receptors, ligands, and immunological effects.

Receptors	Ligands	Probiotic effects	Model	References
TOLL-LIKE RECEPTORS (TLRs)
TLR2	Peptidoglycan	Down-regulate IL-12	Mouse cell lines	(94)
TLR2	LTA	Down-regulate IL-8, balance IL-10/IL-12	Human epithelial Caco-2 cell line	(92, 196)
TLR2, TLR4, RP105/MD	EPS	Down regulate IL-6, IL-8, MCP-1,	Porcine intestinal cell lines	(101, 197)
TLR9	Unmethylated CpG DNA	Suppress NF-κB signaling pathway	Porcine cell lines, Mouse cell lines	(198, 199)
NUCLEOTIDE-BINDING OLIGOMERIZATION DOMAIN-LIKE RECEPTORS (NLRs)
NOD1 and NOD2	Meso-DAP, MDP	Up-regulate IL-10, suppress the production of IL-12	Mouse cell lines	(94)
C-TYPE-LECTIN RECEPTORS (CLRs)
DC-SIGN	SlpA	Up-regulate IL-10, IL-4	Human cell lines	(200)
G-PROTEIN-COUPLED RECEPTORS (GPCRs)
GPR41 GPR43 GPR109A	Acetate, propionate, and butyrate	Down-regulate TNF-α, IL-6, IL-12, and NO up-regulate IL-10	Human cell lines	(201); (202)