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Lactic acid bacteria secrete toll like receptor 2 stimulating and macrophage immunomodulating bioactive factors
- Ren, Chengcheng, Cheng, Lianghui, Sun, Yue, Zhang, Qiuxiang, de Haan, Bart J., Zhang, Hao, Faas, Marijke M., de Vos, Paul
- Journal of functional foods 2020 v.66 pp. 103783
- Toll-like receptor 2, health effects assessments, health promotion, humans, immunomodulation, interleukin-10, lactic acid bacteria, ligands, macrophages, tumor necrosis factor-alpha
- Lactic acid bacteria (LAB) can support host health and crosstalks between ligands on bacterial cells and Toll-like receptors (TLR) are known as key inducers of these health effects. LAB-secreted bioactive factors also possess health-promoting properties but the underlying mechanisms remain to be identified. Here, we report that secreted factors of different LAB strains induce cytokine (IL-10 and TNF-α) production by THP1-differentiated human macrophages in a species- and strain-dependent manner. LAB-secreted products also drive immune-stimulating and anti-pathogenic M1-macrophage polarization. Moreover, bacterial supernatants induce species- and strain-dependent TLR2 activation. Several bacterial strains such as L. casei CCFM9 and L. brevis CCFM498 cannot activate TLR signaling, but their secreted products strongly activate TLR2. This indicates that LAB-secreted components may further boost the functional effects of bacterial strains. Our results confirm direct interactions of LAB-secreted components with TLRs, and provide novel insights in how LABs may provide immune-modulation.