How polluted air causes heart risk

COLUMBUS, Ohio, April 15 (UPI) -- Exposure to polluted air appears to trigger a release of white blood cells that leads to inflammation and risk of heart disease, U.S. researchers say.

Senior author Sanjay Rajagopalan, a professor of cardiovascular medicine at Ohio State University, says a normal immune response to a pathogen or other foreign body produces inflammation -- the body's protective attempt to remove injurious stimuli such as an infection and begin healing.

However, 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.

The Ohio State University scientists predict the damage may originate in fluid that lines the lung. Tiny molecules in the fluid change structure after being exposed to polluted air and the change appears to set off this cascade of damaging white blood cell behavior by activating a receptor labeled "toll-like receptor 4."

This receptor recognizes specific characteristics of pathogens and then sends out signals to activate other players in the immune system, Rajagopalan said.

In the study, mice that lacked this molecule didn't produce as much inflammation after exposure to pollution as normal mice, suggesting that toll-like receptor 4 has a prominent role in the body's response to chronic exposure to particulate matter.

The findings are published in the journal Circulation Research.