Abstract
Epidemiological studies demonstrate an association between short term exposure to ambient particulate matter (PM) and cardiorespiratory morbidity and mortality. Although the biological mechanisms of these adverse effects are unknown, emerging data suggest a key role for oxidative stress. Ambient PM and diesel exhaust particles (DEP) contain redox cycling organic chemicals that induce pro-oxidative and pro-inflammatory effects in the lung. These responses are suppressed by N-acetylcysteine (NAC), which directly complexes to electrophilic DEP chemicals and exert additional antioxidant effects at the cellular level. A proteomics approach was used to study DEP-induced responses in the macrophage cell line, RAW 264.7. We demonstrate that in the dose range 10-100 microg/ml, organic DEP extracts induce a progressive decline in the cellular GSH/GSSG ratio, in parallel with a linear increase in newly expressed proteins on the two-dimensional gel. Using matrix-assisted laser desorption ionization time-of-flight mass spectrometry and electrospray ionization-liquid chromatography/mass spectrometry/mass spectrometry analysis, 32 newly induced/NAC-suppressed proteins were identified. These include antioxidant enzymes (e.g. heme oxygenase-1 and catalase), pro-inflammatory components (e.g. p38MAPK and Rel A), and products of intermediary metabolism that are regulated by oxidative stress. Heme oxygenase-1 was induced at low extract dose and with minimal decline in the GSH/GSSG ratio, whereas MAP kinase activation required a higher chemical dose and incremental levels of oxidative stress. Moreover, at extract doses >50 microg/ml, there is a steep decline in cellular viability. These data suggest that DEP induce a hierarchical oxidative stress response in which some of these proteins may serve as markers for oxidative stress during PM exposures.
Highlights
Epidemiological studies demonstrate an association between short term exposure to ambient particulate matter (PM)1 and cardiorespiratory morbidity and mortality [1,2,3]
How does ambient PM induce oxidative stress? When exposed to intact diesel exhaust particles (DEP) or organic extracts made from these particles, macrophages and epithelial cells respond by producing reactive oxygen species (ROS) [16, 17]
Much remains to be learned about the role of oxidative stress in PM-induced adverse health effects, we have demonstrated that organic DEP extracts induce a wide range of biological effects in epithelial cells and macrophages (16 –18, 21)
Summary
Epidemiological studies demonstrate an association between short term exposure to ambient particulate matter (PM) and cardiorespiratory morbidity and mortality [1,2,3]. Much remains to be learned about the role of oxidative stress in PM-induced adverse health effects, we have demonstrated that organic DEP extracts induce a wide range of biological effects in epithelial cells and macrophages (16 –18, 21). This includes the induction of pro-inflammatory and cytotoxic effects, which can be suppressed by the thiol agent Nacetylcysteine (NAC) [16, 18]. This includes disruption of the mitochondrial inner membrane potential, cytochrome c release, and caspase 9 activation [17] In addition to these harmful effects, organic DEP components have been shown to induce cytoprotective responses, including the expression of an antioxidant enzyme, heme oxygenase 1 (HO-1) [26]. Based on these diverse effects, we have postulated that DEP may induce a hierarchy of oxidative stress effects, which range from cytoprotective to injurious [19, 26]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
