Tyndallized Bacteria Preferentially Induce Human Macrophage M1 Polarization: An Effect Useful to Balance Allergic Immune Responses and to Control Infections

Macrophage polarization is a dynamic process through which macrophages acquire specific features whose extremes are represented by M1 and M2 polarization. Interleukin (IL)-6, IL-1 beta, IL-12 and IL-8 belong to M1 macrophages while transforming growth factor-beta (TGF-beta belongs to M2 cytokines. M2 polarization prevalence is observed in allergic diseases. Tyndallization is a thermal process able to inactivate microorganisms and to allow their use for chronic respiratory disease treatment via immune response modulation. The present study explores the effects of a blend of tyndallized bacteria (TB) on macrophage polarization. THP-1-derived macrophages were exposed to different concentrations of TB (10(6), 5 x 10(6), 10(7), 5 x 10(7), 10(8) CFU/mL) and then cell viability and TB phagocytosis, and IL-8, IL-1 beta, IL-6, IL-12 and TGF-beta 1 gene expression and release were assessed. TB were tolerated, phagocyted and able to increase IL-8, IL-1 beta and IL-6 gene expression and release IL-12 gene expression, as well as decrease TGF-beta 1 gene expression and release. The effects on IL-8, IL-6 and TGF-beta 1 release were confirmed in human monocyte-derived macrophages (hMDMs) exposed to TB. In conclusion, TB promote M1 polarization, and this mechanism might have valuable potential in controlling allergic diseases and infections, possibly preventing disease exacerbations.

Automated summary

Macrophage polarization is a process where specific features are acquired by macrophages, represented by M1 and M2 polarization. M1 macrophages include IL-6, IL-1 beta, IL-12, and IL-8, while M2 cytokines include TGF-beta. This study explores the effects of tyndallized bacteria (TB) on macrophage polarization.