Midpolarity and Nonpolar Wood Smoke Particulate Matter Fractions Deplete Glutathione in RAW 264.7 Macrophages

Abstract

Wood smoke particulate matter (PM) is a complex mixture of components falling in a spectrum of highly polar to nonpolar species. Wood smoke PM is a likely factor in pulmonary disease and induces oxidative damage. Most toxicity studies focus upon nonpolar species such as polycyclic aromatic hydrocarbons (PAHs). However, the role of more polar PM constituents as toxicants is not clear. In this work, we evaluated the ability of multiple fractions of varying polarity to deplete glutathione (GSH) in RAW 264.7 macrophages and BEAS-2B bronchial epithelial cells. We utilized hot pressurized (subcritical) water to fractionate wood smoke PM into seven fractions of decreasing polarity. In contrast to polar fractions, midpolarity and nonpolar fractions exhibited greater GSH depletion (ED50 at PM concentrations of approximately 50 microg/mL). GSH depletion caused by nonpolar fractions (extracted at 250-300 degrees C) was associated with the presence of PAHs. In midpolarity fractions (extracted at 100-150 degrees C), oxy-PAHs, syringylguaiacyls, disyringyls, and lower molecular weight PAHs were found. Direct comparison of GSH depletion by individual oxy-PAHs and PAHs suggests that oxy-PAHs are contributors to oxidative stress caused by wood smoke PM. However, other unidentified PM constituents contribute to GSH depletion as well. The results indicate the toxicological importance of oxygenated organics found in midpolarity PM fractions.

Cytokine responses induced by diesel exhaust particles are suppressed by PAR-2 silencing and antioxidant treatment, and driven by polar and non-polar soluble constituents

“…This notion is corroborated by earlier observations from BEAS-2B cells, where NAC suppressed CXCL8 responses induced by low-polar benzene-extractable DEP-constituents (Kawasaki et al, 2001). Moreover, decreasing polarity of fractionated organic extracts from wood smoke particles has been associated with increased oxidative capacity (GSH-depletion) in both RAW 264.7 macrophages and BEAS-2B cells (Kubatova et al, 2006). In contrast to the non-polar soluble fraction, the highly polar soluble DEP-OE only induced an IL-6 response.…”

“…A study on fractionated organic extracts (OE) from wood-smoke particles suggests that the mid-polar and non-polar soluble constituents account for the majority of glutathione depletion in BEAS-2B cells and RAW 264.7 macrophages (Kubatova et al, 2006). PAHs and PAH derivatives may bind to and activate the aryl hydrocarbon receptor (AhR) leading to up-regulation of cytochrome P450 (CYP)-genes.…”

Biomass smoke exposures: toxicology and animal study design

“…While whole-animal exposures are considered closer to the human condition, in vitro models have been taken advantage of in particulate exposures. These types of systems include primary cells from rats and mice, as well as transformed cell lines including RAW264.7 (Kubatova et al 2006;Leonard et al 2000) and CHO (Hytonen et al 1983). In addition to the use of cell culture systems, certain studies utilized explants from rats or rabbits to assay woodsmoke particulate effects.…”

A semi-automated system for quantifying the oxidative potential of ambient particles in aqueous extracts using the dithiothreitol (DTT) assay: results from the Southeastern Center for Air Pollution and Epidemiology (SCAPE)

“…Both cellular (Xia et al, 2006;Kubátová et al, 2006;Bonvallot et al, 2001;Hiura et al, 1999;Antonini et al, 1998) and acellular methods (Zomer et al, 2011;Mudway et al, 2011;Jung et al, 2006;Cho et al, 2005;Venkatachari et al, 2005;Frampton et al, 1999) have been developed to measure the oxidative potential of PM. Both types of methods have advantages and disadvantages.…”