Diesel and biodiesel exhaust particle effects on rat alveolar macrophages with in vitro exposure

Abstract

Combustion emissions from diesel engines emit particulate matter which deposits within the lungs. Alveolar macrophages (AM) encounter the particles and attempt to engulf the particles. Emissions particles from diesel combustion engines have been found to contain diverse biologically active components including metals and polyaromatic hydrocarbons which cause adverse health effects. However little is known about AM response to particles from the incorporation of biodiesel. The objective of this study was to examine the toxicity in Wistar Kyoto rat AM of biodiesel blend (B20) and low sulfur petroleum diesel (PDEP) exhaust particles. Particles were independently suspended in media at a range of 1–500µg/mL. Results indicated B20 and PDEP initiated a dose dependent increase of inflammatory signals from AM after exposure. After 24hr exposure to B20 and PDEP gene expression of cyclooxygenase-2 (COX-2) and macrophage inflammatory protein 2 (MIP-2) increased. B20 exposure resulted in elevated prostaglandin E2 (PGE2) release at lower particle concentrations compared to PDEP. B20 and PDEP demonstrated similar affinity for sequesteration of PGE2 at high concentrations, suggesting detection is not imparied. Our data suggests PGE2 release from AM is dependent on the chemical composition of the particles. Particle analysis including measurments of metals and ions indicate B20 contains more of select metals than PDEP. Other particle components generally reduced by 20% with 20% incoporation of biodiesel into original diesel. This study shows AM exposure to B20 results in increased production of PGE2 in vitro relative to diesel.

Impact of biodiesel on regulated and unregulated emissions, and redox and proinflammatory properties of PM emitted from heavy-duty vehicles

“…Another study reported that the application of 20% soy-based biodiesel in an uncontrolled light-duty diesel engine resulted in 20-30% higher concentrations of inflammatory mediators (IL-6, IP-10, G-CSF) in treated BEAS-2B cells and in bronchoalveolar lavage fluid in mice than diesel fuel (Fukagawa et al, 2013). Bhavaraju et al (2014) suggested that particle composition is important for driving cellular inflammatory signals and demonstrated that alveolar macrophage exposure to 20% biodiesel resulted in increased production of prostaglandin E 2 (PGE 2 ) relative to diesel. Grigoratos et al (2014) showed higher oxidative activity with increasing biodiesel blending when testing two light-duty vehicles with and without a DPF over the NEDC and Artemis cycles.…”

In Vitro Transformation of Human Bronchial Epithelial Cells by Diesel Exhaust Particles: Gene Expression Profiling and Early Toxic Responses

“…Primary canine AMs exposed to 100 µg DEP/ml (SRM1650a) were shown to induce formation of AA, PGE 2 , and 8-iso-PGF 2α ( Beck-Speier et al , 2005 ). In a study of primary rat AM exposed to low concentrations (1 and 10 µg/ml) of low sulfur DEP, release of PGE 2 was induced, whereas higher concentrations (100 and 500 µg/ml) attenuated the responses ( Bhavaraju et al , 2014 ). Consequently, altered secretion of eicosanoids could potentially serve as mediators of DEP-exposure.…”

Metabolic Profiling as Well as Stable Isotope Assisted Metabolic and Proteomic Analysis of RAW 264.7 Macrophages Exposed to Ship Engine Aerosol Emissions: Different Effects of Heavy Fuel Oil and Refined Diesel Fuel

“…Previous studies using submerged culture exposure of collected particles show induction of cytotoxicity and inflammatory signals in epithelial cells as well as macrophages [ 4 , 6 ]. Our results, determined using the more realistic air-liquid interface cell exposure, support these findings by adding metabolic inflammatory signals found under aerosol exposure.…”

“…As inhalation is the main route of aerosol exposure, the lungs are primarily affected. Many studies have investigated the effects of particulate matter (PM) emissions on lung cells (both in vitro and in vivo [ 4 – 7 ]), but most of these studies have focused on the use of submerged experiments. While useful for studying the effects of particles present in aerosols, these exposures are less representative of real-world inhalation of combustion emissions.…”