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UNIVERSITY OF ROCHESTER

This application addresses broad Challenge Area (04) Clinical Research, and specific Challenge Topic, 04-ES-102: Investigating gene x environment interaction using controlled human exposures. Increases in ambient particulate matter (PM) are associated with morbidity and mortality from pulmonary and cardiovascular disease. The mechanisms and genetic determinants of susceptibility represent gaps in our understanding of the health effects of PM air pollution. Ultrafine particles (UFP, <100 nm diameter) may be particularly important with regard to cardiovascular effects because of their high specific surface area and reactive surface chemistry, with potential to deliver reactive oxygen species (ROS) to the lung and vascular space. This project will combine physiologic measures of vascular and cardiac function with novel markers of nitric oxide (NO) bioavailability and transport to test the following hypotheses: 1. Ambient UFP exposure impairs pulmonary & systemic vascular function, in part by altering NO transport and bioavailability. 2. Dysfunction in selected oxidant defense genes increases susceptibility to the pulmonary and cardiovascular effects of UFP. 3. In susceptible subjects, UFP pulmonary and cardiovascular effects will be related to markers of systemic oxidative stress, and to UFP oxidative potential. Aim: Conduct a human clinical exposure study examining pulmonary and cardiovascular responses to ambient UFP in healthy subjects with and without reduction in function of 2 antioxidant genes. Our approach will be to conduct a randomized, double-blind, 2-period crossover clinical study of exposure to concentrated ambient UFP and clean, filtered air. We will study 3 groups of 12 subjects each, with differing genotypes as follows: 1) GSTM1 null, 2) Nrf2 -617A/C, and 3) "wild type" for both genes (GSTM1+ and Nrf2 -617C/C). Effects of exposure on pulmonary vascular function will be assessed by measuring changes in pulmonary capillary blood volume and shifts in peripheral blood leukocyte adhesion molecule expression. Systemic vascular function will be assessed using blood pressure and heart rate, forearm plethysmography and reactive hyperemia, platelet activation, and circulating microparticles. Our hypothesis that NO bioavailability and transport are involved in the effects on vascular function will be tested by measuring arterial/venous gradients of nitrite, FeNOHb, and SNOHb. Cardiac function will be assessed noninvasively using impedance cardiography (ICG). Airway inflammation will be assessed by measuring pulmonary NO exchange. We will measure markers of oxidative stress/lipid peroxidation in plasma and urine. Our hypotheses will be supported if we see evidence for impaired pulmonary or systemic vascular function or altered cardiac function in one or both of the subject groups with the candidate SNPs, with a positive relationship between these effects and markers of oxidative stress. Finally, we expect to see a relationship between the oxidative potential of the UFP aerosol and physiologic effects, suggesting that at least a portion of the oxidative stress is exogenous. These studies will identify pathways, mechanisms, and genetic determinants of susceptibility for the cardiovascular effects of UFP exposure.

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