title: Associations between microvascular function and short-term exposure to traffic-related air pollution and particulate matter oxidative potential.
abstract: Short-term exposure to ambient air pollution has been associated with acute increases in cardiovascular hospitalization and mortality. However, causative chemical components and underlying pathophysiological mechanisms remain to be clarified. We hypothesized that endothelial dysfunction would be associated with mobile-source (traffic) air pollution and that pollutant components with higher oxidative potential to generate reactive oxygen species (ROS) would have stronger associations.
  
  
  
  We carried out a cohort panel study in 93 elderly non-smoking adults living in the Los Angeles metropolitan area, during July 2012-February 2014. Microvascular function, represented by reactive hyperemia index (RHI), was measured weekly for up to 12 weeks (N = 845). Air pollutant data included daily data from regional air-monitoring stations, five-day average PM chemical components and oxidative potential in three PM size-fractions, and weekly personal nitrogen oxides (NOx). Linear mixed-effect models estimated adjusted changes in microvascular function with exposure.
  
  
  
  RHI was inversely associated with traffic-related pollutants such as ambient PM2.5 black carbon (BC), NOx, and carbon monoxide (CO). An interquartile range change increase (1.06 μg/m(3)) in 5-day average BC was associated with decreased RHI, -0.093 (95 % CI: -0.151, -0.035). RHI was inversely associated with other mobile-source components/tracers (polycyclic aromatic hydrocarbons, elemental carbon, and hopanes), and PM oxidative potential as quantified in two independent assays (dithiothreitol and in vitro macrophage ROS) in accumulation and ultrafine PM, and transition metals.
  
  
  
  Our findings suggest that short-term exposures to traffic-related air pollutants with high oxidative potential are major components contributing to microvascular dysfunction.
authors.affiliation: Department of Epidemiology, School of Medicine, University of California, Irvine, Irvine 224 Irvine Hall, Irvine, CA, 92617-7555, USA.
authors.forename: Xian
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Epidemiology, School of Medicine, University of California, Irvine, Irvine 224 Irvine Hall, Irvine, CA, 92617-7555, USA.
authors.forename: Norbert
authors.initials: N
authors.lastname: Staimer
authors.affiliation: Department of Epidemiology, School of Medicine, University of California, Irvine, Irvine 224 Irvine Hall, Irvine, CA, 92617-7555, USA.
authors.forename: Tomas
authors.initials: T
authors.lastname: Tjoa
authors.affiliation: Department of Statistics, School of Information and Computer Sciences, University of California, Irvine, Irvine, CA, USA.
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Gillen
authors.affiliation: Environmental Chemistry and Technology Program, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: James J
authors.initials: JJ
authors.lastname: Schauer
authors.affiliation: Environmental Chemistry and Technology Program, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: Martin M
authors.initials: MM
authors.lastname: Shafer
authors.affiliation: Department of Civil and Environmental Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, USA.
authors.forename: Sina
authors.initials: S
authors.lastname: Hasheminassab
authors.affiliation: Department of Civil and Environmental Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, USA.
authors.forename: Payam
authors.initials: P
authors.lastname: Pakbin
authors.affiliation: Susan Samueli Center for Integrative Medicine, and Cardiology Division, Department of Medicine, School of Medicine, University of California, Irvine, Irvine, CA, USA.
authors.forename: John
authors.initials: J
authors.lastname: Longhurst
authors.affiliation: Department of Civil and Environmental Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, USA.
authors.forename: Constantinos
authors.initials: C
authors.lastname: Sioutas
authors.affiliation: Department of Epidemiology, School of Medicine, University of California, Irvine, Irvine 224 Irvine Hall, Irvine, CA, 92617-7555, USA. rdelfino@uci.edu.
authors.forename: Ralph J
authors.initials: RJ
authors.lastname: Delfino
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000032:analysis; D000818:Animals; D001160:Arterioles / Q000502:physiology; D002140:California / Q000453:epidemiology; D002248:Carbon Monoxide / Q000032:analysis; D015331:Cohort Studies; D004781:Environmental Exposure / Q000032:analysis*; D005260:Female; D006801:Humans; D006940:Hyperemia / Q000453:epidemiology*; D008264:Macrophages / Q000378:metabolism; D008297:Male; D009589:Nitrogen Oxides / Q000032:analysis; D010084:Oxidation-Reduction; D010126:Ozone / Q000032:analysis; D052638:Particulate Matter / Q000032:analysis; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D001335:Vehicle Emissions
chemical_list: D000393:Air Pollutants; D009589:Nitrogen Oxides; D052638:Particulate Matter; D017382:Reactive Oxygen Species; D001335:Vehicle Emissions; D010126:Ozone; D002248:Carbon Monoxide
keywords: Air pollution; Microvascular function; Oxidative potential; Particulate matter components