Inactivation of M111 Protein Gene Modifies Streptococcus Pyogenes Interactions with Mouse Macrophages In Vitro.

Immunomodulatory properties of S. pyogenes protein M111 were studied on the model of Gurov strain and its isogenic mutant not expressing M protein. Mouse resident peritoneal macrophages were incubated with bacteria and generation of nitroxide and superoxide anions and production of IL-6, IL-10, and IL-17 were evaluated. Protein M111 modified macrophage response: it exhibited antiphagocytic activity, prevented ROS formation, and stimulated the production of anti-inflammatory cytokine IL-10. The results suggested that this protein could serve in the bacteria as a factor suppressing the host defense forces and promoting the realization of the strategy beneficial for pathogens - escape from the host immune defense.