Citation:

Vitucci, E. AND S. McCullough. Piecing Together the Puzzle: Identifying the Role Oxidative Stress and the Alveolar Epithelium Play in Air Pollution Induced Cardiovascular Disease. 2019 Society of Toxicology Annual Meeting, Baltimore, MD, March 10 - 14, 2019.

Impact/Purpose:

Presentation of the development and use of an in vitro organotypic model to identify the mechanisms involved in adverse cardiovascular effects of inhaled toxicant exposures and for the development of novel multi-dimensional adverse outcome pathways. .

Description:

An estimated 3.5-million people die every year from air pollution-induced cardiovascular disease (API-CVD); however, while in vivo data has demonstrated associations between induced CVD and systemic oxidative stress, the causative molecular mechanisms driving API-CVD are still poorly understood. To identify the mechanisms of action driving API-CVD, we developed a unique, tri-culture in vitro model that represents the interface of the alveolar epithelial barrier (AEB) and the cardiovascular system. We hypothesized that air pollutant exposure of human alveolar-like epithelial cells (H441) would induce oxidative stress in adjacent, but physically separated, human pulmonary vasculature cells leading to vascular damage. To test this hypothesis, we exposed confluent, electrically-resistant, and small molecular-impermeable monolayers of H441 cells, grown on the apical surface of Transwell permeable membranes, to the ubiquitous air pollutant, diesel exhaust particulates (DEP), with human lung fibroblasts on the underside of the Transwell membrane and human microvascular lung endothelial cells (HULEC) in the basal compartment. Upon DEP exposure, we identified a variety of oxidative stress responsive genes induced in the directly exposed H441 cells and in the indirectly exposed HULEC, including heme oxygenase 1 (HMOX-1) and NAD(P)H dehydrogenase [quinone] 1 (NQO1). These changes in gene expression occurred despite a lack of change in trans-epithelial electrical resistance (TEER) and small molecule (20kDa fluorescein isothiocyanate (FITC)-dextran) permeability, suggesting that they result from the release of epithelial/fibroblast-derived mediators and/or compounds/metabolites that traverse the epithelial cells. Collectively, these data suggest that induction of oxidative stress in nearby endothelial cells may be mediated by epithelial cells, and may be an important mechanism of API-CVD. We conclude that we have developed a relevant, in vivo-like, in vitro model of the AEB-cardiovascular system interface which can be used to identify the elusive molecular mechanisms driving API-CVD. Ultimately, data derived from this model can be used to identify therapeutic targets, biomarkers of both susceptibility and exposure effects, and can encourage the continued development of similar biomimetic models resulting in a reduction of non-essential animal testing.

Record Details: