Release of the Pro-Inflammatory Markers by BEAS-2B Cells Following In Vitro Exposure to Biodiesel Extracts

Abstract

Biodiesel, an alkyl ester of plant oils that can be used in an unmodified diesel engine, is the first renewable diesel fuel alternative to become a commercially accepted part of our nation's energy infrastructure. For traditional diesel fuel exhaust, it has been demonstrated that the particulate matter (PM) organic components play a role in acute inflammatory reactions. However, there have been only a few cytotoxicity and mutagenicity studies on biodiesel emissions. In this study, BEAS-2B cells, a transformed human airway epithelial cell line, were exposed in vitro to the PM organic extracts from Standard Reference Material (SRM) 1975, soy ethyl ester (SEE), soy methyl ester (SME), and petroleum diesel for 24 hours. This study demonstrated that the organic extracts of biodiesel PM in an aqueous solution can increase the release of pro-inflammatory cytokines IL-8 and IL-6 by respiratory epithelial cells. On a microgram PM equivalent per ml (μg PM eq/ml) basis, exposure to biodiesel extracts was associated with a greater release of IL-8 and IL-6 relative to organic extracts of two diesel PM samples. The dose range tested was not cytotoxic. It was also noted that the solvent exchange method, which was used to prepare the aqueous exposure doses, may not be appropriate for the investigation of biodiesel extracts, though it has been used extensively in petroleum diesel research. A valuable new finding from these experiments is that the soluble organic fraction (SOF) of biodiesel PM begins to elicit a cytokine response in BEAS-2B cells at an exposure lower than petroleum diesel PM extract (approximately 40 μg PM eq/ml). However, more research is required to better characterize the potency of the organic fraction of biodiesel compared to petroleum diesel.

Biodiesel exhaust: The need for a systematic approach to health effects research

“…43 Another study showed that unspecified biodiesel particles in solution induced less apoptosis in human airway epithelial cells compared with mineral diesel particles in solution, 40 while Swanson and co-workers (2009) found that cytotoxicity was not consistently higher or lower in soybean biodiesel particle-exposed cells compared with mineral diesel-exposed cells. 51 Betha and co-workers (2012) exposed human epithelial carcinoma cells (A549) to particles extracted from the combustion of waste cooking oil-based biodiesel. 41 They found that engine load significantly impacted outcomes, and that cytotoxicity and oxidative stress were generally higher for B100 relative to mineral diesel.…”

The Impact of Biodiesel on Pollutant Emissions and Public Health

“…Swanson and coworkers used airway epithelial cell bioassays to evaluate the inflammatory potential of extracts from diesel and biodiesel PM. Exposure to biodiesel PM extracts appeared to be a more potent inflammatory stimulant than exposure to diesel PM extracts (Swanson et al, 2007). Finch and coworkers studied inhalation exposure of rats to engine exhaust generated by burning 100% soy-derived biodiesel to provide data for compliance with the Tier 2 requirements of the U.S. EPA Fuel Registration Program (Finch et al, 2002).…”

Cumulative exposure assessment for trace-level polycyclic aromatic hydrocarbons (PAHs) using human blood and plasma analysis

“…Additionally, PAHs have been implicated in adverse reproductive outcomes, somatic mutations, and decrease in children's IQ [28][29][30]. We have investigated inhalation exposure to PAHs from diesel exhaust and the link with pulmonary cytokine expression [31][32][33].…”