Relevance: The goal of this application is to understand the pathway by which participate air pollutants (a.k.a. particulate matter or PM) lead to worsening of allergic asthma by impacting dendritic cells (DC) in the immune system (IS). This research is relevant to understanding how air pollutants contribute to the development of asthma, and proposes rational therapy to block the impact of of PM on asthma through the use of a novel class of antioxidants. The principal hypothesis is that PM and adsorbed redox cycling organic chemicals alter DC function to favor Th2 skewing of the IR. The proposal is that oxidative stress perturbs DC activities such as antigen presentation, cellular maturation, cytokine production and/or co-stimulatory activity that are key for T-cell activation and Th2 differentiation. A pathway that is regulated by the transcription factor, Nrf2, protects against the pro-inflammatory and adjuvant effects of PM. Nrf2 accomplishes this by inducing the expression of a battery of phase II antioxidant enzymes that exert anti-inflammatory effects.
Aim 1 will determine in a DC adoptive transfer model the mechanism(s) by which oxidative stress promotes Th2 skewing in vitro and in vivo. Diesel exhaust particles, ambient ultrafine particles and pro-oxidative PM chemical fractions will be used to determine their effect on DC immunoregulatory properties, including antigen uptake, antigen presentation, maturation, cytokine/chemokine production, transgenic T-cell activation, and co-stimulatory activity. In vivo skewing of the IR will be further expored in transgenic mice that express a nlL-4-GFP transgene knocked into the IL-4 promoter.
Aim 2 will determine whether the Nrf2-mediated antioxidant defense pathway, by modification of DC function, regulates PM-induced oxidative stress and asthma. This will be accomplished by comparing wild type with Nrf2-deficient animals. This study will determine whether interference in phase II enzyme expression leads to exaggerated PM effects on DC antigen presenting activity and whether Nrf2 deficiency promotes Th2 skewing and allergic inflammation in vivo. Proteome analysis will be conducted to reveal in vivo oxidative stress markers in the BAL fluid that can used to study PM oxidative stress effects. In collaboration with Projects 2 &3, proteome analysis will also be conducted on human nasal lavage fluid to develop a comprehensive understanding of the allergic inflammatory effects of DEP in the nose, including the dynamic equilibrium between pro-and antioxidant pathways.
Aim 3 will determine whether Nrf2-mediated phase II enzyme expression during treatment with alpha-lipoic acid and sulfurophane protects against PM oxidative stress effects and asthma exacerbation in vivo and modulation of DC function in vitro.
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