Research Projects

A growing body of epidemiologic literature has associated ambient particulate matter (PM) with cardiovascular morbidity and mortality. Although the observed association has been relatively consistent, biological mechanisms through which inhaled PM could influence systemic and cardiovascular health endpoints are unclear. In addition, most studies focus on PM in urban areas, which have been shown to have a different mixture of constituents than PM from rural areas. Ongoing ARB-funded research demonstrates that platelets are activated in the circulation of mice that are exposed to concentrated ambient particles from the Central Valley, and that platelet activation in some exposures is associated with an increase in circulating pro-inflammatory mediators. In addition, there is evidence that platelet and pro-inflammatory mediator release varies between seasons and locations, suggesting differential contributions of endotoxin, polycyclic aromatic hydrocarbons (PAH) and reactive oxygen species generation related to metals in the particulate mixture.

The study will evaluate lung inflammation by histopathology and inflammatory mediator production by lung tissue, systemic markers of platelet activation and concentrations of several inflammatory mediators in the blood. The investigators expect to see different correlations between biological endpoints and summer/winter and urban/rural PM2.5. They also anticipate that pro-inflammatory and pro-coagulant responses to the particulate challenges will vary with the amount of PAH, soluble metal, and endotoxin in the particles to which the mice are exposed. The project addresses the topic of whether or not there are significant differences in responses to PM of differing chemical composition, and will support the question as to whether it would be more health protective to reduce one type of PM as opposed to the ambient mixture as a whole.