Adenosine synthase A contributes to recurrent Staphylococcus aureus infection by dampening protective immunity.

Background: Staphylococcus aureus is a common human pathogen capable of causing diverse illnesses with possible recurrent infections. Although recent studies have highlighted the role of cellular immunity in recurrent infections, the mechanism by which S. aureus evades host responses remains largely unexplored.

Methods: This study utilizes in vitro and in vivo infection experiments to investigate difference of pro-inflammatory responses and subsequent adaptive immune responses between adsA mutant and WT S. aureus strain infection.

Findings: We demonstrated that adenosine synthase A (AdsA), a potent S. aureus virulence factor, can alter Th17 responses by interfering with NLRP3 inflammasome-mediated IL-1β production. Specifically, S. aureus virulence factor AdsA dampens Th1/Th17 immunity by limiting the release of IL-1β and other Th polarizing cytokines. In particular, AdsA obstructs the release of IL-1β via the adenosine/A2aR/NLRP3 axis. Using a murine infection model, pharmacological inhibition of A2a receptor enhanced S. aureus-specific Th17 responses, whereas inhibition of NLRP3 and caspase-1 downregulated these responses. Our results showed that AdsA contributes to recurrent S. aureus infection by restraining protective Th1/Th17 responses.

Interpretation: Our study provides important mechanistic insights for therapeutic and vaccination strategies against S. aureus infections.

Funding: This work was supported by grants from Shenzhen Peacock project (KQTD2015033-117210153), and Guangdong Science and Technology Department (2020B1212030004) to J.H. and China Postdoctoral Science Foundation (2019M663167) to BZZ. We also thank the L & T Charitable Foundation, the Guangdong Science and Technology Department (2020B1212030004), and the Program for Guangdong Introducing Innovative and Entrepreneurial Teams (2019BT02Y198) for their support.