Arsenic Compromises Conducting Airway Epithelial Barrier Properties in Primary Mouse and Immortalized Human Cell Cultures

Abstract

Arsenic is a lung toxicant that can lead to respiratory illness through inhalation and ingestion, although the most common exposure is through contaminated drinking water. Lung effects reported from arsenic exposure include lung cancer and obstructive lung disease, as well as reductions in lung function and immune response. As part of their role in innate immune function, airway epithelial cells provide a barrier that protects underlying tissue from inhaled particulates, pathogens, and toxicants frequently found in inspired air. We evaluated the effects of a five-day exposure to environmentally relevant levels of arsenic {<4μM [~300 μg/L (ppb)] as NaAsO2} on airway epithelial barrier function and structure. In a primary mouse tracheal epithelial (MTE) cell model we found that both micromolar (3.9 μM) and submicromolar (0.8 μM) arsenic concentrations reduced transepithelial resistance, a measure of barrier function. Immunofluorescent staining of arsenic-treated MTE cells showed altered patterns of localization of the transmembrane tight junction proteins claudin (Cl) Cl-1, Cl-4, Cl-7 and occludin at cell-cell contacts when compared with untreated controls. To better quantify arsenic-induced changes in tight junction transmembrane proteins we conducted arsenic exposure experiments with an immortalized human bronchial epithelial cell line (16HBE14o-). We found that arsenic exposure significantly increased the protein expression of Cl-4 and occludin as well as the mRNA levels of Cl-4 and Cl-7 in these cells. Additionally, arsenic exposure resulted in altered phosphorylation of occludin. In summary, exposure to environmentally relevant levels of arsenic can alter both the function and structure of airway epithelial barrier constituents. These changes likely contribute to the observed arsenic-induced loss in basic innate immune defense and increased infection in the airway.

Airway epithelial cell exposure to distinct e-cigarette liquid flavorings reveals toxicity thresholds and activation of CFTR by the chocolate flavoring 2,5-dimethypyrazine

“…Primary MTE cells were chosen for Ussing chamber studies because they are representative of a polarized epithelium necessary for biophysical measurements. C57Bl/6 wild type mice were used for these cells that were cultured as previously described [ 23 ]. MTE cells were seeded onto 6.5 mm semipermeable filters coated with CFB matrix and cultured at 37 °C with 5 % CO 2 .…”

Inorganic arsenic causes intestinal barrier disruption

“…25 The effect of inorganic As on components of tight junctions was shown previously in a mouse trachea epithelial cell model. 26 Those authors showed that epithelial cells of the respiratory pathway exposed to As(III) (0.60-290 µg/L) exhibited altered patterns of localization of some tight junction proteins. The data obtained in the present study show for the first time that this toxic effect can also be produced at intestinal level in cases of acute exposure to As(III) and As(V).…”

Impacts of the combined exposure to seawater acidification and arsenic on the proteome of Crassostrea angulata and Crassostrea gigas

“…ZO-1 are scaffolding proteins integral in the link between the tight junction and the actin cytoskeleton, modulating cell to cell adherence processes. Different elements have been shown to cause tight junction restructuring and deficiency, for instance in mouse respiratory cells exposed to As (Sherwood et al, 2013) and in Tegillarca granosa clams exposed to Cd (Bao et al, 2016). Therefore, the present data suggest that As caused impairment of cell to cell adherence proteins in C. angulata.…”