Bafilomycin A1 triggers Streptococcus mutans-induced neutrophil extracellular trap (NET) production 9124

Abstract Description Neutrophil extracellular traps (NETs) promote thrombosis and contribute to infectious disease progression. Our previous study showed that commensal oral streptococci entering the bloodstream induces NET formation on injured heart valves via IgG-activated platelets, promoting vegetation maturation in infective endocarditis. To investigate mechanisms of Streptococcus mutans-induced NET formation, we tested various signaling pathway modulators. Bafilomycin A1 (BafA1), an autophagy inhibitor, enhanced S. mutans-induced NET production, while other autophagy inhibitors, such as 3-MA and LY294002, had no effect. BafA1 promoted elastase translocation and PAD4-mediated histone citrullination in S. mutans-stimulated neutrophils. However, NET production induced by BafA1 required ROS and neutrophil elastase but was independent of histone citrullination. S. mutans infection increased LC3-II accumulation, but BafA1 reduced LC3-II levels in neutrophils. BafA1 also inhibited neutrophil phagocytic killing of S. mutans. Beyond canonical phagocytosis, S. mutans induced LC3-associated phagocytosis (LAP) via Rubicon expression and Rubicon-LC3 colocalization. BafA1 reduced Rubicon expression, suggesting LAP suppression contributes to BafA1-induced NET production. These results indicate that BafA1 reduces LC3-II accumulation, inhibits phagocytic killing, and enhances elastase translocation, driving S. mutans-induced NET formation. Funding Sources Supported by the National Science and Technology Council (NSTC112-2320-B-038-055-MY3 and NSTC112-2320-B-038-061). Topic Categories Innate Immune Responses and Host Defense: Cellular Mechanisms (INC)