Tyndallized bacteria induce macrophage polarization toward M1 polarization: an effect useful to balance allergic immune responses

Abstract

Macrophage (M) polarization with a prevalence in M2 has been shown to have a relevant impact on the pathogenesis of upper and lower airway allergic diseases. IL-6, IL-1b and IL-8 are among the cytokines produced by M1 macrophages while TGF-b is included among the cytokines produced by M2 macrophages. Tyndallization is a thermal process able to inactivate microorganisms. Formulations containing inactivated microorganisms and/or their components, defined as postbiotics, can exert beneficial effects on human chronic respiratory diseases via modulation of immune responses. The present study explores the effects on macrophage polarization by a blend of tyndallized bacteria (TB) containing Lactobacillus Casei, Lactobacillus Acidophilus, Lactobacillus Plantarum, Streptococcus Thermophilus. Human macrophage-like THP1 cells were exposed to different concentrations of TB (106, 5x106, 107, 5x107, 108 CFU/ml) and then cell viability (MTS), TB phagocytosis and gene expression and release of IL-1b, IL-6, IL-8 and TGF b were assessed. The obtained results demonstrated that TB were well tolerated at all the tested concentrations and were phagocyted after 30 minutes in a dose-dependent manner. In addition, treatment with TB was able to: a) increase the release of IL-1b; b) increase the gene expression of IL-6 and IL-8; c) decrease the gene expression of TGFb. In conclusion, this study demonstrates that TB are capable to orientate M polarization toward M1, a functional phenotype that protects from allergic diseases and that can control viral infections thus preventing disease exacerbations.