title: ROS production and gene expression in alveolar macrophages exposed to PM(2.5) from Baghdad, Iraq: Seasonal trends and impact of chemical composition.
abstract: The objective of this study was to assess the impact of changes in atmospheric particulate matter (PM) composition on oxidative stress markers in an in-vitro alveolar macrophage (AM) model. Fifty-three PM2.5 samples were collected during a year-long PM sampling campaign in Baghdad, Iraq, a semi-arid region of the country. Monthly composites were analyzed for chemical composition and for biological activity using in-vitro measurements of ROS production and gene expression in the AM model. Twelve genes that were differentially expressed upon PM exposure were identified and their co-associations with the composition of PM2.5 were examined. Ten of those genes were up-regulated in January and April composites; samples which also exhibited high ROS activity and relatively high PM mass concentration. ROS production was statistically correlated with total PM2.5 mass, levoglucosan (a wood burning tracer) and several trace elements of the PM (especially V and Ni, which are associated with oil combustion). The expression of several cytokine genes was found to be moderately associated with PM mass, crustal materials (indication of dusty days or dust storms) and certain metals (e.g. V, Fe and Ni) in the PM. Thus, the ROS activity association with PM2.5, may, in part, be driven by redox-active metals. The antioxidant response genes (Nqo1 and Hmox1) were moderately associated with polyaromatic hydrocarbons (PAHs) and showed a good correlation (r-Pearson of >0.7) with metals linked to vehicle-related emissions (i.e. Cu, Zn and Sb). Examining these associations in a larger sample pool (e.g. daily samples) would improve the power of the analysis and may strengthen the implication of these chemicals in the oxidative stress of biological systems, which could aid in the development of new metrics of PM toxicity.
authors.affiliation: Environmental Chemistry and Technology Program, University of Wisconsin-Madison, 660 N. Park St., Madison, WI 53706, USA. Electronic address: shamad@wisc.edu.
authors.forename: Samera H
authors.initials: SH
authors.lastname: Hamad
authors.affiliation: Environmental Chemistry and Technology Program, University of Wisconsin-Madison, 660 N. Park St., Madison, WI 53706, USA; Wisconsin State Laboratory of Hygiene, 2601 Agricultural Drive, Madison, WI 53718, USA. Electronic address: jjschauer@wisc.edu.
authors.forename: James J
authors.initials: JJ
authors.lastname: Schauer
authors.affiliation: Wisconsin State Laboratory of Hygiene, 2601 Agricultural Drive, Madison, WI 53718, USA. Electronic address: dksieprawska@wisc.edu.
authors.forename: Dagmara S
authors.initials: DS
authors.lastname: Antkiewicz
authors.affiliation: Environmental Chemistry and Technology Program, University of Wisconsin-Madison, 660 N. Park St., Madison, WI 53706, USA; Wisconsin State Laboratory of Hygiene, 2601 Agricultural Drive, Madison, WI 53718, USA. Electronic address: mmshafer@wisc.edu.
authors.forename: Martin M
authors.initials: MM
authors.lastname: Shafer
authors.affiliation: Iraqi Ministry of Environment, Al-Andalus Square, Baghdad, Iraq. Electronic address: ahmed_khudhair@ymail.com.
authors.forename: Ahmed Kh
authors.initials: AK
authors.lastname: Kadhim
mesh_terms: D000393:Air Pollutants / Q000032:analysis; D000397:Air Pollution / Q000706:statistics & numerical data; D015870:Gene Expression / Q000187:drug effects; D007493:Iraq; D016676:Macrophages, Alveolar / Q000187:drug effects* / Q000502:physiology; D008670:Metals / Q000032:analysis / Q000633:toxicity; D008954:Models, Biological; D052638:Particulate Matter / Q000633:toxicity*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012621:Seasons; D001335:Vehicle Emissions / Q000032:analysis
chemical_list: D000393:Air Pollutants; D008670:Metals; D052638:Particulate Matter; D017382:Reactive Oxygen Species; D001335:Vehicle Emissions
keywords: Chemical composition; Gene expression; Inflammation; Particulate matter; ROS; Urban aerosols