Polluted air leads to disease by promoting widespread inflammation

Ohio State University Research: Chronic inhalation of polluted air appears to activate a protein that triggers the release of white blood cells, setting off events that lead to widespread inflammation, according to new research in an animal model. This finding narrows the gap in researchers’ understanding of how prolonged exposure to pollution can increase the risk for cardiovascular problems and other diseases.

The research group, led by Ohio State University scientists, has described studies in mice suggesting that chronic exposure to very fine particulate matter triggers events that allow white blood cells to escape from bone marrow and work their way into the bloodstream. Their presence in and around blood vessels alters the integrity of vessel walls and they also collect in fat tissue, where they release chemicals that cause inflammation.
Sanjay Rajagopalan

The cellular activity resembles an immune response that has spiraled out of control. A normal immune response to a pathogen or other foreign body requires some inflammation, but when inflammation is excessive and has no protective or healing role, the condition can lead to an increased risk for cardiovascular diseases, diabetes and obesity, as well as other disorders.

…“Our main hypothesis is that particulate matter stimulates inflammation in the lung, and products of that inflammation spill over into the body’s circulation, traveling to fat tissue to promote inflammation and causing vascular dysfunction,” said Sanjay Rajagopalan, professor of cardiovascular medicine at Ohio State and senior author of the study. “We haven’t identified the entire mechanism, but we have evidence now that activation of TLR4 influences this response.”

…In an editorial in the same issue of Circulation Research, Daniel Conklin of the University of Louisville wrote, “Is the mystery solved regarding the mechanism how inhaled [fine particulate matter] exposure stimulates vascular inflammation and injury? Well, probably not completely, but the present scenario laid out … connects findings from their study with many disparate human and animal epidemiological/exposure studies into a plausible story.”

A plate from Gray's Anatomy (not the TV show)