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Chronic arsenic exposure in nanomolar concentrations compromises wound response and intercellular signaling in airway epithelial cells.

ABSTRACT: Paracrine ATP signaling in the lung epithelium participates in a variety of innate immune functions, including mucociliary clearance, bactericide production, and as an initiating signal in wound repair. We evaluated the effects of chronic low-dose arsenic relevant to U.S. drinking water standards (i.e., 10 ppb [130nM]) on airway epithelial cells. Immortalized human bronchial epithelial cells (16HBE14o-) were exposed to 0, 130, or 330nM arsenic (as Na-arsenite) for 4-5 weeks and examined for wound repair efficiency and ATP-mediated Ca(2+) signaling. We found that chronic arsenic exposure at these low doses slows wound repair and reduces ATP-mediated Ca(2+) signaling. We further show that arsenic compromises ATP-mediated Ca(2+) signaling by altering both Ca(2+) release from intracellular stores (via metabotropic P2Y receptors) and Ca(2+) influx mechanisms (via ionotropic P2X receptors). To better model the effects of arsenic on ATP-mediated Ca(2+) signaling under conditions of natural exposure, we cultured tracheal epithelial cells obtained from mice exposed to control or 50 ppb Na-arsenite supplemented drinking water for 4 weeks. Tracheal epithelial cells from arsenic-exposed mice displayed reduced ATP-mediated Ca(2+) signaling dynamics similar to our in vitro chronic exposure. Our findings demonstrate that chronic arsenic exposure at levels that are commonly found in drinking water (i.e., 10-50 ppb) alters cellular mechanisms critical to airway innate immunity.

SUBMITTER: Sherwood CL

PROVIDER: S-EPMC3576008 | biostudies-literature | 2013 Mar

REPOSITORIES: biostudies-literature

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Chronic arsenic exposure in nanomolar concentrations compromises wound response and intercellular signaling in airway epithelial cells.

Sherwood Cara L CL Lantz R Clark RC Boitano Scott S

Toxicological sciences : an official journal of the Society of Toxicology 20121130 1

Paracrine ATP signaling in the lung epithelium participates in a variety of innate immune functions, including mucociliary clearance, bactericide production, and as an initiating signal in wound repair. We evaluated the effects of chronic low-dose arsenic relevant to U.S. drinking water standards (i.e., 10 ppb [130nM]) on airway epithelial cells. Immortalized human bronchial epithelial cells (16HBE14o-) were exposed to 0, 130, or 330nM arsenic (as Na-arsenite) for 4-5 weeks and examined for woun ...[more]

PMID: 23204110

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Project description:This study chronically exposed human lung epithelial BEAS-2B cells to low-dose arsenic trioxide in vitro to elucidate cancer promoting gene signaling networks (GSNs) associated with As-transformed (B-As) cells. Following a six month exposure, exposed cells were assessed for enhanced cell proliferation, colony formation, invasion ability and in vivo tumor formation compared to control cell lines. Collected mRNA was subjected to whole genome expression microarray profiling followed by in silico Ingenuity Pathway Analysis (IPA) to identify lung carcinogenesis modes of action. B-As cells displayed significant increases in proliferation, colony formation and invasion ability compared to BEAS-2B cells. B-As injections into nude mice resulted in development of primary and secondary metastatic tumors. As exposure resulted in widespread up-regulation of genes associated with mitochondrial metabolism and increased ROS protection suggesting mitochondrial dysfunction. Carcinogenic initiation via ROS and epigenetic mechanisms was further supported by altered DNA repair, histone, and ROS-sensitive signaling. NF-κB, MAPK and NCOR1 signaling disrupted PPARα/δ-mediated lipid homeostasis. A ‘pro-cancer’ GSN identified increased survival, proliferation, inflammation, metabolism, anti-apoptosis and mobility signaling. IPA-ranked signaling networks identified altered p21, EF1α, Akt, MAPK, and NF-κB signaling networks promoting genetic disorder, altered cell cycle, cancer and changes in nucleic acid and energy metabolism. In conclusion, transformed B-As cells with their whole genome GSN profile provide an in vitro As model for future lung cancer signaling research and data for chronic As exposure risk assessment. Whole genome expression profiling was conducted on arsenic (III) oxide-exposed human immortalized lung epithelial cells (BEAS-2B) following 6 month in vitro chronic exposure. As2O3 exposed cells (B-As) gene expression were compared to unexposed, passage control (B-Control) cell gene expression. Three B-As and four B-Control biological replicate cDNA samples were analyzed.

Project description:Following an official request to EFSA from the European Commission, EFSA assessed the chronic dietary exposure to inorganic arsenic (iAs) in the European population. A total of 13,608 analytical results on iAs were considered in the current assessment (7,623 corresponding to drinking water and 5,985 to different types of food). Samples were collected across Europe between 2013 and 2018. The highest mean dietary exposure estimates at the lower bound (LB) were in toddlers (0.30 ?g/kg body weight (bw) per day), and in both infants and toddlers (0.61 ?g/kg bw per day) at the upper bound (UB). At the 95th percentile, the highest exposure estimates (LB-UB) were 0.58 and 1.20 ?g/kg bw per day in toddlers and infants, respectively. In general, UB estimates were two to three times higher than LB estimates. The mean dietary exposure estimates (LB) were overall below the range of benchmark dose lower confidence limit (BMDL 01) values of 0.3-8 ?g/kg bw per day established by the EFSA Panel on Contaminants in the Food Chain in 2009. However, for the 95th percentile dietary exposure (LB), the maximum estimates for infants, toddlers and other children were within this range of BMDL 01 values. Across the different age classes, the main contributors to the dietary exposure to iAs (LB) were 'Rice', 'Rice-based products', 'Grains and grain-based products (no rice)' and 'Drinking water'. Different ad hoc exposure scenarios (e.g. consumption of rice-based formulae) showed dietary exposure estimates in average and for high consumers close to or within the range of BMDL 01 values. The main uncertainties associated with the dietary exposure estimations refer to the impact of using the substitution method to treat the left-censored data (LB-UB differences), to the lack of information (consumption and occurrence) on some iAs-containing ingredients in specific food groups, and to the effect of food preparation on the iAs levels. Recommendations were addressed to improve future dietary exposure assessments to iAs.

Project description:This study chronically exposed human lung epithelial BEAS-2B cells to low-dose arsenic trioxide in vitro to elucidate cancer promoting gene signaling networks (GSNs) associated with As-transformed (B-As) cells. Following a six month exposure, exposed cells were assessed for enhanced cell proliferation, colony formation, invasion ability and in vivo tumor formation compared to control cell lines. Collected mRNA was subjected to whole genome expression microarray profiling followed by in silico Ingenuity Pathway Analysis (IPA) to identify lung carcinogenesis modes of action. B-As cells displayed significant increases in proliferation, colony formation and invasion ability compared to BEAS-2B cells. B-As injections into nude mice resulted in development of primary and secondary metastatic tumors. As exposure resulted in widespread up-regulation of genes associated with mitochondrial metabolism and increased ROS protection suggesting mitochondrial dysfunction. Carcinogenic initiation via ROS and epigenetic mechanisms was further supported by altered DNA repair, histone, and ROS-sensitive signaling. NF-ÎºB, MAPK and NCOR1 signaling disrupted PPARÎ±/Î´-mediated lipid homeostasis. A âpro-cancerâ GSN identified increased survival, proliferation, inflammation, metabolism, anti-apoptosis and mobility signaling. IPA-ranked signaling networks identified altered p21, EF1Î±, Akt, MAPK, and NF-ÎºB signaling networks promoting genetic disorder, altered cell cycle, cancer and changes in nucleic acid and energy metabolism. In conclusion, transformed B-As cells with their whole genome GSN profile provide an in vitro As model for future lung cancer signaling research and data for chronic As exposure risk assessment. Whole genome expression profiling was conducted on arsenic (III) oxide-exposed human immortalized lung epithelial cells (BEAS-2B) following 6 month in vitro chronic exposure. As2O3 exposed cells (B-As) gene expression were compared to unexposed, passage control (B-Control) cell gene expression. Three B-As and four B-Control biological replicate cDNA samples were analyzed.

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Chronic arsenic exposure in nanomolar concentrations compromises wound response and intercellular signaling in airway epithelial cells.

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Chronic arsenic exposure in nanomolar concentrations compromises wound response and intercellular signaling in airway epithelial cells.

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