Timothy O'Toole, Ph.D.
University of Louisville
NIEHS grantees found that short-term exposure to particulate matter smaller than 2.5 micrometers (PM2.5), a common air pollutant, can induce oxidative stress in the lungs. This oxidative stress may, in turn, trigger vascular insulin resistance, a critical factor in the development of diabetes. This novel link between pulmonary oxidative stress and vascular insulin resistance may explain how exposure to air pollution increases the risk of developing both cardiovascular and metabolic diseases.
The researchers studied mice fed a normal or a high-fat diet, exposing them to either air concentrated with PM2.5 or filtered air. They then measured insulin sensitivity and inflammation. Upon exposure to PM2.5, mice developed vascular insulin resistance, which is associated with development of diet-induced obesity and diabetes, even in the absence of a high-fat diet. They also found that reducing oxidative stress in the lungs, either with antioxidant treatment or by overexpressing an enzyme responsible for creating antioxidants, prevented the PM2.5-induced vascular insulin resistance and inflammation.
The findings provide a new template for understanding how PM2.5 exposure might affect both cardiovascular processes and metabolic changes by inducing vascular insulin resistance. According to the authors, these results also suggested that conditions associated with decreased antioxidant capacity in the lung, such as asthma, smoking, advanced age, and influenza, could increase susceptibility to the cardiovascular effects of air pollution.
Citation: Haberzettl P, O'Toole TE, Bhatnagar A, Conklin DJ. 2016. Exposure to fine particulate air pollution causes vascular insulin resistance by inducing pulmonary oxidative stress. Environ Health Perspect 124(12):1830−1839.