<i>Levilactobacillus brevis</i> IBARAKI‐TS3 Isolated From Pickles Promotes Production of Interleukin‐10 via Toll‐Like Receptor 2 in Human M2 Macrophages

M2 macrophages play an important role in food allergy. Several studies have reported that lactic acid bacteria isolated from pickles exert antiallergic effects. We investigated the effects of several strains of lactic acid bacteria on the immune function of M2 macrophages. M2 macrophages differentiated from THP-1 cell line by interleukin-4 (IL-4) and IL-13 strongly expressed CD163, CD206, and HMOX1 mRNA. Levilactobacillus brevis IBARAKI-TS3 (IBARAKI-TS3) isolated from pickles was identified as a lactic acid bacterium that enhances the expressions of IL-10 and EBI3 mRNA in M2 macrophages. IBARAKI-TS3 induced the expression of genes involved in Toll-like receptor (TLR) signaling, such as IRAK, mitogen-activated protein kinases (MAPKs), and NF-κB mRNA. IBARAKI-TS3-induced IL-10 production was suppressed by anti-TLR2-neutralizing antibodies. Furthermore, the IBARAKI-TS3-induced increase in IL-10 levels was significantly reduced in TLR2-knockdown M2 macrophages compared to M2 macrophages. These results suggest that IBARAKI-TS3 promotes of IL-10 production via TLR2 in M2 macrophages.