New study finds diesel exhaust changes immune response in human lungs

Inhaled air pollution is a well-known human health hazard. Traffic-related air pollution is associated with an increased risk of respiratory diseases such as asthma and Chronic Obstructive Pulmonary Disease (COPD), enhanced allergic responses, and an increased risk of lung infections.

A new two-part study (read here and here) led by Dr. Neeloffer Mookherjee, a research scientist at the Children’s Hospital Research Institute of Manitoba and an associate professor in the Rady Faculty of Health Sciences at the University of Manitoba, and Dr. Christopher Carlsten, Director of the Air Pollution Exposure Laboratory at the University of British Columbia, examined the effects of exposure to diesel exhaust (DE) on human lungs. They studied whether or not diesel exhaust effects are enhanced when also exposed to allergens – common airborne proteins such as birch, grass, or dust mite that produce abnormal immune response, causing what we know as allergies. The study is the first of its kind to examine the complete protein response to the common real-world combination of DE and allergens in humans.

The researchers found that exposure to DE and allergens together can alter two groups of proteins in the human lung: those related to immune response and infection protection, and those related to inflammation and oxidative stress. The results show a decrease in protective proteins and an increase in inflammatory proteins in the lung, when exposed to the combination.

Interestingly, the same effects are not observed with DE alone, only when it is combined with allergens. This suggests that inhalation of DE or traffic-related air pollution may enhance the risk of lung infections in people who are already susceptible to allergies, by altering the overall protein composition of their lungs.

“Given the high global prevalence of allergies, the results of this study are very important for public health all over the world,” said Dr. Mookherjee. “This deepens the evidence that traffic-related air pollution can be harmful to people who are prone to allergies.”

Dr. Carlsten noted that while exposure to DE in the presence of allergens appears to have particular negative effects on lung health, exposure to DE alone remains a major concern. “We continue to study the specific effects of these same air pollutants on normal and susceptible lungs,” he said.