The acute pulmonary toxicity in mice induced by Staphylococcus aureus, particulate matter, and their combination

Area of Science:

• Environmental Health
• Toxicology
• Immunology

Background:

• Particulate matter (PM) can transport pathogenic bacteria, posing a significant threat to respiratory health.
• Understanding the combined pulmonary toxicity of PM and bacteria like Staphylococcus aureus (S. aureus) is crucial for public health.

Purpose of the Study:

• To investigate the pulmonary toxicity of S. aureus and PM, both individually and in combination, in a mouse model.
• To assess the impact of combined exposure on oxidative stress, inflammatory markers, and immune responses in the lungs.

Main Methods:

• Kunming mice were intratracheally instilled with PM and S. aureus, individually and combined, twice over five days.
• Analysis included oxidative stress markers (MDA, CAT, SOD, T-AOC, GSH/GSSG), nitric oxide (NO), cytokines (IL-4, INF-γ, IL-8), neurotrophins (Substance P), immunoglobulins (IgE), and leukocyte infiltration in lung tissue and bronchoalveolar lavage fluid (BALF).

Main Results:

• Combined PM and S. aureus exposure significantly increased lung MDA, CAT, SOD, and NO, while decreasing T-AOC and GSH/GSSG ratio, indicating heightened oxidative stress.
• Elevated IL-4/INF-γ ratio, IL-4 in BALF, and serum IgE were observed in groups exposed to S. aureus or the combination.
• PM, S. aureus, or their combination led to increased Substance P and IL-8 in BALF and significant leukocyte infiltration into lung tissues.

Conclusions:

• Combined exposure to PM and S. aureus induces a significant lung inflammatory response in mice.
• This inflammatory response is, at least partly, mediated by oxidative stress and inflammatory mediators released from activated immune cells and epithelial cells.
• The findings highlight the synergistic detrimental effects of airborne pollutants and pathogenic bacteria on pulmonary health.