Airborne Staphylococcus aureus Exposure Induces Depression-like Behaviors in Mice via Abnormal Neural Oscillation and Mitochondrial Dysfunction

Airborne Staphylococcus aureus exists widely in the natural environment and is closely related to human health. Growing evidence indicates that environmental air pollution elevates the risk of depressive disorders. However, the potential role of airborne S. aureus in the development of depression remains unclear. This study aims to elucidate the neurotoxic effects and potential mechanisms associated with depression caused by airborne S. aureus. Mice were randomly divided into four groups, and the experimental groups with environmental S. aureus were at 4.89 × 10², 8.89 × 10⁵, and 1.27 × 10⁸ CFU/m³ during four consecutive weeks. Airborne S. aureus exposure contributed to depression-like behaviors in mice, especially in the high-concentration group. The electroencephalography signal analysis identified uncoupling of theta and gamma bands and a shift of the beta rhythm toward delta oscillation in the medial prefrontal cortex of mice. Neuropathological analysis showed uplifted neuroinflammation and elevated levels of oxidative stress in the brain. Neuroinflammation and oxidative stress resulted in mitochondrial dysfunction, which could lead to apoptosis. Together, this study provides a strong basis for understanding the adverse outcomes of airborne S. aureus on mental health disorders.