Research team receives grant to study impact of urban air pollution on TB immunity

An international team of researchers, led by Stephan Schwander, MD, PhD, director of the Center for Global Public Health at the University of Medicine and Dentistry of New Jersey-School of Public Health (UMDNJ-SPH), has received a $2.96 million grant to conduct a "real-world" study on the impact of urban air pollution on the human immune system's ability to resist Mycobacterium tuberculosis, the bacterium that causes tuberculosis (TB). The grant has been awarded by the National Institute of Environmental Health Sciences.

"Air pollution from rapid industrial growth and traffic collide with high levels of TB in many parts of the world," said Dr. Schwander, who is also the interim chair of the Department of Environmental and Occupational Health at UMDNJ-SPH. "Our study will be the first to examine the effect of ambient urban air pollution on the human lung immune system that controls development of TB among individuals exposed to that environment."

An earlier study led by Dr. Schwander identified a link between diesel exhaust particles - a common component of urban air pollution - and changes in the immune response that may increase the likelihood of Mycobacterium tuberculosis disease. Conducted in a laboratory environment, that study showed how diesel exhaust particles suppress the function of immune cells, which, in turn, may cause exposed individuals to be less able to fight off Mycobacterium tuberculosis infections. The newly funded study will take the next step by examining whether those laboratory results can be confirmed in a much larger study conducted in a real-world environment.

The study will recruit individuals in Iztapalapa, a municipality with more than 2 million inhabitants within Mexico City that is known for its high air pollution levels and prevalence of TB cases. It will measure the impact of air pollution exposure on the lung immune system of healthy individuals. Study participants will either have been exposed to Mycobacterium tuberculosis through others with TB in their household and have a latent Mycobacterium tuberculosis infection or be healthy control individuals from the same community without Mycobacterium tuberculosis infection. Another group of healthy study participants will be recruited in New Jersey to allow for a set of separate yet supportive studies of the role of seasonal changes in the composition of the Mexican air pollution material on human immune cell responses. In a laboratory setting, researchers will examine the effect that the Mexican air pollution materials have on lung and blood cells from study participants who are from Iztapalapa and on blood cells from the New Jersey participants.

"Choosing these healthy subject groups is sensible, from a public health perspective, in order to show if fine particulate matter air pollution, such as diesel exhaust, would indeed inhibit the immune response to Mycobacterium tuberculosis," Dr. Schwander added. "If that is so, it could demonstrate how healthy but latently infected individuals could become vulnerable to developing active TB, and how healthy uninfected individuals could become susceptible to new Mycobacterium tuberculosis infection."

Each year, TB afflicts more than eight million people and causes 1.5 million deaths worldwide. Between two and three billion additional people are believed to be latently infected with Mycobacterium tuberculosis globally. TB is particularly prevalent in low- and middle-income countries that are experiencing rapid industrial growth and increases in motor vehicle traffic in densely populated urban areas.