Panel Discussion

Ambient air pollution is associated with premature death caused by heart disease, stroke, chronic obstructive pulmonary disease (COPD) and lung cancer. However, the underlying mechanisms leading to detrimental effects on health by air pollution is yet to be understood. This has made it difficult the development of sensitive and specific biomarkers that, at the molecular level, can report cellular toxicity upon exposure to various air chemicals. Recent studies suggest that RNA oxidation is a sensitive environmental-related biomarker that is implicated in pathogenesis. In this work funded by the HEI through a Rosenblith Young Investigator Award, we applied a novel approach that integrates RNA-seq analysis with detection by immunoprecipitation techniques of the prominent RNA oxidative modification 8-oxo-7,8-dihydroguanosine (8-oxoG). Our goal was to uncover specific transcriptomics oxidation induced by VOCs/ozone mixtures in healthy epithelial lung cells that could be used as sensitive and early indicators of air-induced cell toxicity. We are investigating potential chemical modifications that are induced in mRNAs upon exposure to oxidative-prone air and to study how these perturbations affect normal patterns of cellular regulation. Specifically, we have been investigating: (1) what biochemical mechanisms lead to the breakdown of normal (healthy) transcriptome (mRNA) expression levels in various cellular pathways? And, (2) how is the breakdown of biological function at the molecular level caused by environmentally-induced chemical modifications? As such, we exposed BEAS-2B to the gas and particle phase products formed from reactions of 790 ppb acrolein and 670 ppb methacrolein with 4 ppm ozone (O3). Using this approach, we identified several potential direct targets of oxidation belonging to previously described pathways, as well as uncharacterized pathways on air pollution exposures. We demonstrated the effect of VOCs/O3 mixtures on the morphology of lung cells, suggesting the influence of selective mRNA oxidation in members of pathways regulating physical components of the cells as consistently observed with cellular phenotypes in COPD studies. In addition, we observed the influence of VOC/O3 mixtures on several specific metabolic pathways likely implicated with the incidence of mRNA oxidation and the deregulation of several proteins. Taken together, our study features the strength of combining traditional transcriptome analysis with epitranscriptome mechanistic characterizations to facilitate the discovery of underling processes that are not well described at the molecular level by current approaches. Thus, this presentation will focus on the ways that this research has informed the relationship between the atmospheric agents and molecular cellular responses implicated with diseases. We will discuss our findings uncovering specific mRNAs that are more susceptible to oxidative species and the impact of these modifications on overall cell function. Emphasis will be placed on how these studies have led to distinct biomarkers that can be used to sensitively assess toxicity effects.