CORE--DIESEL EXHAUST COLLECTION AND FRACTIONATION

University Of California Los Angeles, Los Angeles CA

Investigators

Linked publications & trials

Abstract

Description (provided by applicant): In this application, we propose to study the effects of intact DEPs, as well as organic chemical groups fractionated from those particles, for their pro-oxidative and pro-inflammatory effects in vivo and in vitro. Our hypothesis is that among the large number of organic chemicals present in DEP, the PAHs and their oxygenated derivatives (oxy-PAHs, e.g., quinones) are the major chemical groups responsible for oxidative stress effects in the respiratory tract. In order to accomplish our goal, we will obtain light-duty (LD) and heavy-duty (HD) DEPs, which are collected on filters. The particles are scraped off and resuspended by sonication into a small amount of carrier. Intact particles will be used for nasal provocation challenge in humans (Projects 1-4), aerosolized inhalation in mice (Projects 2-4), and in vitro cell culture studies (Projects 2 and 3) to follow the link between oxidative stress and allergic inflammation. In order to demonstrate that specific organic chemical groups are responsible for these effects, we will fractionate particulate organic extracts into asphaltene, aliphatic, aromatic and polar fractions using silica gel chromatography. We will use gas chromatography/mass spectrometry analysis to show that the aromatic fraction is enriched for the PAHs, while the quinones and oxy-PAHs elute with the polar fraction. These fractions will allow us in Projects 2, 3 and 4 to compare the effects of the chromatographed chemical groups to the effects of intact DEP. Not only will this help to determine that specific chemical groups mimic the effect of intact DEP, but will also be helpful in elucidating the principal metabolic pathways (e.g., Phase I and II drug metabolizing pathways) by which DEP chemicals induce oxidative stress and pro-inflammatory effects. In addition, Project 3 will test the possibility that DEP quinones inhibit cyclo-oxygenase II activation by direct covalent modification. Taken together, the Diesel Exhaust Particulate Collection and Fractionation Core will meet the key program objective of demonstrating how organic chemical compounds in DEP lead to allergic inflammation via inducing metabolic pathways involved in oxidative stress.