2007 Progress Report: Oxidative Stress Responses to PM Exposure in Elderly Individuals With Coronary Heart DiseaseEPA Grant Number: R832413C004
Subproject: this is subproject number 004 , established and managed by the Center Director under grant R832413
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: Southern California Particle Center
Center Director: Froines, John R.
Title: Oxidative Stress Responses to PM Exposure in Elderly Individuals With Coronary Heart Disease
Investigators: Delfino, Ralph , Vaziri, Nosratola D , Staimer, Norbert , Neuhausen, Susan
Current Investigators: Delfino, Ralph , Vaziri, Nosratola D , Gillen, Dan , Staimer, Norbert , Neuhausen, Susan , Gastanaga, Victor
Institution: University of California - Irvine
EPA Project Officer: Chung, Serena
Project Period: October 1, 2005 through September 30, 2010 (Extended to September 30, 2012)
Project Period Covered by this Report: October 1, 2006 through September 30, 2007
RFA: Particulate Matter Research Centers (2004) RFA Text | Recipients Lists
Research Category: Health Effects , Air
The overall goal of this study is to advance knowledge on the importance of particle size and composition to the induction of oxidative stress responses in a high-risk population of elderly people with coronary artery disease. We hypothesize that biomarkers of oxidative stress responses will be associated with indoor and outdoor home PM mass and total particle number concentration, which will support the view that PM leads to systemic inflammatory responses. We further hypothesize that biomarkers will be more strongly associated with predicted indoor exposure to PM of outdoor origin (from source tracer analyses). We will also evaluate effects of exposure to specific metals, elemental and organic carbon, and specific organic components used as source tracers. We further hypothesize that biomarker associations with ultrafine and fine PM will be better explained by chemical assays that measure reactive oxygen species and electrophilic activity.
Over a period of seven months (July, 2006 to February, 2007), 33 subjects were followed with weekly blood draws at two new retirement communities, yielding a two-year total of 65 subjects in 4 communities. Venous peripheral blood samples were drawn at the retirement homes using anti-coagulant Vacutainer tubes. The blood samples were taken to a mobile field laboratory (equipped with a Class II Type A biological safety cabinet and a refrigerated benchtop clinical centrifuge) next to the retirement homes, and rapidly separated (< 30 min) into erythrocytes and plasma. After centrifugation, each fraction was aliquoted, coded, and transported frozen on dry ice from the field to the UCI core laboratory and stored at -80°C until tested. Further, whole blood was aliquoted into microcentrifuge vials before centrifugation and immediately put on dry ice as well. So far, around 3,000 Vacutainer blood samples (separated into 6,500 fractions of whole EDTA blood, EDTA plasma, CTAD plasma, RBC lysates, and 9,000 EDTA plasma aliquots) have been collected.
To date, the first year of collected erythrocyte lysates (358 samples) have been assayed for Glutathione Peroxidase-1 (GPx-1) and Superoxide Dismutase (SOD) activity (Cayman Chem., cat. #703102 and #706002), and all of the human EDTA plasma samples (358 samples in total) have been analyzed for Myeloperoxidase using a commercially available 96-well immunoassay kit (Alpco Diagnostics; cat# 30-6631). The mean MPO concentration was 46 ng/mL (SD 109). One subject exhibited very high concentrations over 500 ng/ml. We are investigating explanations for this related to the use of carvedilol for congestive heart failure and other medications. Excluding this subject the mean MPO concentration was 26 ng/mL (SD 30) and is similar to EDTA plasma concentrations found in healthy blood donors.1
All of the samples were run in duplicate and all of the repeated measurements (up to 12 per subject) were analyzed on one plate in order to circumvent inter-assay variation. A temperature controlled, monochromatic microplate reader (VERSAmax™; wavelength range: 340-850 nm) was used for high sample throughput.
Analysis of the relationship between biomarkers of oxidative stress and air pollutants:
Biomarkers from the first year of the panel were analyzed in relation to both measured indoor and outdoor home air pollutants, and estimated air pollutants, including primary and secondary organic carbon, and indoor concentrations of air pollutants of outdoor (home) origin. We measured hourly indoor and outdoor home pollutant gases, PM2.5, total particle number (PN), Aethelometer black carbon (BC), PM2.5 Sunset Labs elemental carbon (EC) and organic carbon including OC1 (most volatile) and OC2-4 (least volatile) fractions. Daily gravimetric PM was measured indoor and outdoor using the Sioutas Impactor (SKC) for quasi-ultrafine (PM0.25), accumulation mode (PM0.25-2.5) and coarse mode (PM2.5-10). We used our recently published data to estimate indoor and outdoor secondary OC2-4 (OCSOA) and primary OC2-4 (OCpri), and to estimate indoor concentrations of these species of outdoor origin using mass balance models.2 Indoor concentrations of particle number and EC of outdoor origin were also estimated.
Data for 30 subjects in the first year of study were analyzed excluding two subjects with frequent infections. The relationship between biomarkers and air pollutant was analyzed with linear mixed effects models controlling for temperature and excluding infections. We assumed a two-stage hierarchical model with random effects at the subject level, nested within the two 6-week phases, and with autoregressive-1 correlation structure.
Many associations were found for erythrocyte glutathione peroxidase (GPx) activity [adjusted per unit hemoglobin concentration (Hb)]. Mixed model estimates showed that GPx significantly decreased with increases in PM0.25, nonsignificantly decreased with PM2.5-10, but there was no association with PM0.25-2.5. There was no significant interaction of particle mass with medications including statins. However, in models for GPx and hourly exposures, a complex pattern emerged.
We found significant interactions between air pollutants and use of rennin-angiotensin-aldosterone system (RAAS) antagonists [angiotensin ΙΙ receptor blockers (ARBs) and angiotensin I converting enzyme inhibitors (ACEIs)]. Subjects on these medications had significantly higher GPx concentrations than subjects who were not on them (median 14.8 vs. 12.6 U/g Hb, respectively, mixed model estimate, 1.6 U/g Hb difference). Among subjects on these medications, significant inverse associations were found for outdoor EC, PN, CO and NO2, and for indoor EC of outdoor origin, and indoor NO2. Models for BC and estimated primary OC were nearly significant, whereas estimated outdoor and indoor SOA was not. Among subjects not on these medications, significant positive associations were found indoor EC of outdoor origin, and indoor primary OC of outdoor origin. Models for outdoor EC and PN, and for indoor PN of outdoor origin were nearly significant, whereas estimated outdoor and indoor SOA was not. Models were stronger for longer averaging times across the week before the blood draw. For instance, among 16 subjects on these medications, GPx decreased by 2.4 U/g Hb per IQR increase of 0.9 μg/m3 EC, 6-day moving average (95% CI: -0.2, -4.5). In contrast, among 14 subjects not on these medications, GPx increased by 1.2 U/g Hb per IQR EC 6-day moving average (95% CI: -0.3, 2.6).
Consistent but less significant inverse associations were found between MPO and exposures representing primary PM aerosols. Overall findings suggest inactivation of antioxidant enzyme activity by primary PM aerosols in elderly people with coronary artery disease treated with ACEIs and ARBs, but the opposite trend in subjects who were not on them.
Evaluation of the 8-isoprostane (8-iso PGF2α) EIA test kit for routine measurements in EDTA plasma samples is underway. Based on the results, routine procedures for the measurement of 8-isoprostane in EDTA plasma samples will be established. We are analyzing data for exhaled hydrocarbons to estimate in vivo lipid peroxidation, and compare this with blood data from Projects 2 and 4. New analyses of MPO and GPx-1 will include data from weekly blood draws in the second year panel (Jul 2005-Feb 2007), which will double the sample size. We will conduct analyses of in vitro data using Project 3 methods data to evaluate the relationship of biomarkers to redox activity in concentrated PM collected under separate finding. Analysis of second year exposure data is also underway to estimate indoor concentrations of outdoor air pollutants under separate funding.
1Bekesi G, Kakucs R, Sandor J, et al. Plasma concentration of myeloperoxidase enzyme in pre- and post-climacterial people: related superoxide anion generation. Experimental Gerontology 2001;37:137-148.
2Polidori A, Arhami M, Delfino RJ, Allen R, Sioutas C. Indoor-outdoor relationships, trends and carbonaceous content of fine particulate matter in retirement communities of the Los Angeles basin. J Air Waste Manage Assoc, 2007; 57:366-379.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
|Other subproject views:||All 35 publications||15 publications in selected types||All 15 journal articles|
|Other center views:||All 241 publications||157 publications in selected types||All 157 journal articles|
||Delfino RJ, Staimer N, Tjoa T, Polidori A, Arhami M, Gillen DL, Kleinman MT, Vaziri ND, Longhurst J, Zaldivar F, Sioutas C. Circulating biomarkers of inflammation, antioxidant activity, and platelet activation are associated with primary combustion aerosols in subjects with coronary artery disease. Environmental Health Perspectives 2008;116(7):898-906.||
Supplemental Keywords:Health Effects, Human health, Sensitive populations, Dose-response, Enzymes, Particulates, Epidemiology, Environmental chemistry, Modeling,, RFA, Health, Scientific Discipline, Air, particulate matter, Health Risk Assessment, Risk Assessments, Biochemistry, Ecology and Ecosystems, elderly adults, particulates, atmospheric particulate matter, human health effects, PM 2.5, airway disease, cardiovascular vulnerability, airborne particulate matter, air pollution, human exposure, vascular dysfunction, cardiovascular disease, human health risk
Progress and Final Reports:Original Abstract
Main Center Abstract and Reports:R832413 Southern California Particle Center
Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R832413C001 Contribution of Primary and Secondary PM Sources to Exposure & Evaluation of Their Relative Toxicity
R832413C002 Project 2: The Role of Oxidative Stress in PM-induced Adverse Health Effects
R832413C003 The Chemical Properties of PM and their Toxicological Implications
R832413C004 Oxidative Stress Responses to PM Exposure in Elderly Individuals With Coronary Heart Disease
R832413C005 Ultrafine Particles on and Near Freeways