Lack of S100A8 Impairs Lung-Protective Immunity Against Streptococcus pneumoniae

Area of Science:

• Immunology
• Pulmonology
• Microbiology

Background:

• S100A9 is vital for lung antibacterial immunity against pneumococcal pneumonia.
• The specific role of S100A8 in lung antibacterial immunity remains unclear.

Purpose of the Study:

• To investigate the role of S100A8 in lung antibacterial immunity against Streptococcus pneumoniae.
• To explore the underlying mechanisms of S100A8's function in pneumonia.

Main Methods:

• Quantified S100A8 in patient BAL fluid using ELISA.
• Utilized wild-type and S100A8 knockout mice infected with S. pneumoniae.
• Analyzed bacterial clearance, disease progression, lung pathology, and leukocyte recruitment.

Main Results:

• S100A8 levels were elevated in bacterial pneumonia patients.
• S100A8 deficiency increased bacterial load and mortality in mice.
• S100A8 absence led to neutrophil elastase-mediated degradation of surfactant proteins A and D.
• Recombinant S100A8/A9 therapy rescued S100A8 knockout mice.

Conclusions:

• S100A8 deletion impairs lung immunity against S. pneumoniae in mice.
• S100A8/S100A9 complex analysis may differentiate bacterial from viral pneumonia.