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The Effect of Composition, Size, and Solubility on Acute Pulmonary Injury in Rats Following Exposure to Mexico City Ambient Particulate Matter Samples
Citation:
Snow, S., A. De Vizcaya-Ruiz, A. Osornio-Vargas, R. Thomas, M. Schladweiler, J. Mcgee, AND U. Kodavanti. The Effect of Composition, Size, and Solubility on Acute Pulmonary Injury in Rats Following Exposure to Mexico City Ambient Particulate Matter Samples. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. Taylor & Francis, Inc., Philadelphia, PA, 77(19):1164-82, (2014).
Impact/Purpose:
This study was designed to examine the relationship between chemical composition as well as size and resulting lung injury for ambient particulate matter samples collected in two different regions of Mexico City, Mexico using a rat model. Study shows that the Southern residential region that is recently industrialized contained more metals in the air per mass of PM than the ambient air in Northern region. Lung injury from Southern PM sample likewise was slightly more severe than injury caused by PM sample from Northern region. And that the particle core induced more lung injury than water soluble fraction.
Description:
Particulate matter (PM) associated metals contribute to the adverse cardiopulmonary effects following exposure to air pollution. Here, we investigated how variation in the composition and size of ambient PM collected from two distinct regions in Mexico City relates to toxicity differences. Male Wistar Kyote rats (14 wk) were intratracheally instilled with chemically characterized PM10 and PM2.5 from the North and PM10 from the South of Mexico City (3 mg/kg). Both water-soluble and acid-leachable fractions contained several metals with levels generally higher in PM10 South. The insoluble and total, but not soluble, fractions of all PM induced pulmonary damage that was indicated by significant increases in neutrophilic inflammation, and several lung injury biomarkers including total protein, albumin, lactate dehydrogenase activity, and γ-glutamyl transferase activity 24 and 72 h post-exposure. PM10 North and PM2.5 North also significantly decreased levels of the antioxidant ascorbic acid. Increases in lung mRNA biomarkers of inflammation (TNF-α and MIP-2), oxidative stress (HO-1, LOX-1, and iNOS), and thrombosis (TF and PAI-1), as well as decreased levels of the fibrinolytic protein tPA, further demonstrated pulmonary injury following Mexico City PM exposure. These responses were more pronounced after exposure to PM10 South (PM10 South>PM10 North>PM2.5 North), which contained higher levels of redox active transition metals that may have contributed to these specific differences in selected lung gene markers. These findings provide evidence that the surface chemistry of the PM core and not the water-soluble fraction played an important role in governing in vivo pulmonary toxicity responses of Mexico City PM.