The SaeR/S gene regulatory system induces a pro-inflammatory cytokine response during Staphylococcus aureus infection

Area of Science:

• Microbiology
• Immunology
• Bacterial Pathogenesis

Background:

• Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) drives increased staphylococcal disease incidence.
• Mechanisms of S. aureus pathogenesis and host inflammation remain incompletely understood.
• The SaeR/S two-component system is a global regulator of virulence in S. aureus.

Purpose of the Study:

• To investigate the role of the S. aureus SaeR/S system in mediating host inflammatory responses.
• To determine the impact of SaeR/S on cytokine production during S. aureus infection.
• To elucidate the contribution of SaeR/S to bacterial pathogenesis and host mortality.

Main Methods:

• Utilized mouse models of S. aureus pathogenesis (invasive and skin infections, peritonitis).
• Generated and infected mice with wild-type and isogenic saeR/S deletion mutant S. aureus strains.
• Measured pro-inflammatory cytokine levels (TNF-α, IFN-γ, IL-6, IL-2) in vivo and ex vivo using human blood.

Main Results:

• S. aureus infection induced significant pro-inflammatory cytokine production.
• Mice infected with the saeR/S deletion mutant showed markedly reduced cytokine levels.
• SaeR/S-influenced factors induced cytokines in human blood ex vivo.
• SaeR/S mediated robust IFN-γ production in both invasive and skin infections.
• SaeR/S was critical for bacterial survival and increased host mortality during peritonitis.

Conclusions:

• The SaeR/S two-component system plays a pivotal role in regulating S. aureus-induced pro-inflammatory cytokine production.
• SaeR/S contributes significantly to bacterial pathogenesis, host survival, and mortality during S. aureus infections.
• This study elucidates a key bacterial mechanism linking virulence regulation to host inflammatory responses.