While it has long been known that exposure to ozone, a major component of urban air pollution, is associated with increased cardiovascular and pulmonary hospitalizations and deaths, the actual mechanisms involved remain unclear.

Now a new study in the current issue of the Journal of Immunology shows that mice exposed to ozone experience a reduction in important microbe-fighting cells that leave the lungs vulnerable to infection.

A team led by John W. Hollingsworth, MD, PhD, at Duke University Medical Center, Durham, NC, exposed mice to either free air or ozone, before making them breathe an aerosolized bacterium known as Escherichia coli LPS.

Pre-exposure to ozone dramatically reduced inflammatory cell accumulation to the lower airways after the mice inhaled LPS.  The smaller concentration of inflamed cells was associated with enhanced apoptosis, or instant cell death, of both lung macrophages and systemic circulating monocytes, which are vital antibacterial defense systems.

The team plans to expand the study ozone exposure on the pulmonary system to include body-wide immune responses.

To read the abstract, click here.