Exposure to Acyl Homoserine Lactone Enhances Survival of Streptococcus pyogenes in Murine Macrophages

Streptococcus pyogenes is an opportunistic pathogen causing infections of the skin and upper respiratory tract of the human host. Due to the polymicrobial community present in the human host, S. pyogenes comes across several interspecies signalling molecules. Among these molecules, N-(3-oxododecanoyl)-l-homoserine lactone (Oxo-C12) modulates the morphology, thereby enhancing virulence characteristics of S. pyogenes. After the initial attachment of the bacteria to the host cell, the pathogen needs to invade the host immune system for a successful infection to occur. The host immune system is activated upon infection, where macrophages engulf the pathogen, thereby killing the bacteria. However, S. pyogenes have evolved various strategies to evade the host immune response. In this study, we investigate the role of Oxo-C12 in enhancing the survival of S. pyogenes M3 in murine macrophages. The observed Oxo-C12-mediated increased survival in murine macrophages was through increased lysozyme and acid stress resistance. Moreover, Oxo-C12 increased the survival of S. pyogenes in normal human serum. Thus, understanding the role of interspecies signalling in enhancing the survival strategies of S. pyogenes in the host will further help fill the gap for therapeutics development.