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Chronic Exposure to Pollution Boosts Atherosclerosis in Mice

Long-term, low-dose exposure induced vascular inflammation

TUESDAY, Dec. 20 (HealthDay News) -- In mice susceptible to heart disease, chronic exposure to even low doses of air pollution alters vasomotor tone, causes vascular inflammation and potentiates atherosclerosis, according to a study in the Dec. 21 issue of the Journal of the American Medical Association. Exposure to particulate matter boosts plaque accumulation in animals fed either a low-fat or high-fat diet.

Qinghua Sun, M.D., Ph.D., of the Mount Sinai School of Medicine in New York, and colleagues studied 28 apolipoprotein E-/- (apoE-/-) mice fed either high-fat chow or normal chow. Over six months, the mice were exposed to ambient particles of less than 2.5 μm (PM2.5) or filtered air (FA) for six hours each day, five days a week. While the concentration of particulate matter in the chamber was roughly sixfold higher than ambient air in Manhattan, it was about the same exposure when normalized over six months.

For the high-fat chow group, exposure to PM2.5 resulted in a 41.5% mean composite plaque area versus 26.2% for FA. In the normal chow group, PM2.5 exposure resulted in a mean composite plaque area of 19.2% versus 13.2% for FA. In mice fed with high-fat chow and exposed to PM2.5, there was a 1.5-fold increase in lipid content in the aortic arch. This group of mice also had exaggerated vasoconstrictor responses to phenylephrine and serotonin challenge in the thoracic aorta and had marked increases in macrophage infiltration.

"These findings support the need for targeted studies that help delineate the precise constituents in particulate matter that confer this risk," the authors conclude.

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