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DRUG/XENOBIOTIC-METABOLIZING ENZYME (XME) EXPRESSION IN THE EPIAIRWAY IN VITRO HUMAN AIRWAY MODEL: UTILITY FOR ASSESSING TRACHEAL/BRONCHIAL BIOTRANSFORMATION OF INHALED PHARMACEUTICALS AND ENVIORNMENTAL CHEMICALS.
Hayden, P.J., Bolarcich, J., Stopler, G., Jackson, G.R., Klausner, M.
MatTek Corporation, Ashland, MA, USA.
Presented at the American Thoracic Society 2006 Annual Meeting, San Diego CA, May 19-24 (2006).
Keywords: 3-Methylcholanthrene (3MC), AIR-100, Biotransformation, CPY3A7, CYP expression, CYP isoforms, CYP1A1, CYP1B1, CYP2A6, CYP2B6, CYP2C19, CYP2C8, CYP2D6, CYP2E1, CYP3A4, CYP3A5, Conjugative phase II enzymes, Drugs, Environmental chemicals, EpiAirway, Human tracheal/bronchial epithelium, In vivo-like XME activities, Inhaled pharmaceuticals, Metabolism, Mucociliary epithelium, Mutagenic metabolites, Occupational chemicals, Oxidative phase I enzymes, Pseudostratified epithelium, Tobacco smoke, Toxic metabolites, Xenobiotic metabolizing enzyme (XME)
Endpoints: CYP 1A1 activity, Cytochrome P45 expression, Glutathione S-Transferase (GTS) activity, RT_PCR gene expression, UDP-Glucuronosyltransfase activity
Materials Tested: 1-chloro-2,4-dinitrobenzene, 3-methycholanthrene, 4-methylumbellipherone, Ethoxyresorufin
Summary:
Human tracheal/bronchial epithelium contains xenobiotic metabolizing capabilities provided by a variety of phase I (oxidative) and phase II (conjugative) enzyme systems. These XMEs can play an important role in biotransformation of inhaled drugs, tobacco smoke and environmental/ occupational chemicals. Biotransformation of inhaled chemicals may lead to altered drug activity or formation of toxic/mutagenic metabolites.
This study evaluated expression of XMEs in EpiAirway, a highly differentiated in vitro model of human tracheal/bronchial epithelium that is cultured at the air-liquid interface to facilitate in vivo-like chemical exposures (AIR-100).
RT-PCR gene expression experiments were conducted to evaluate baseline and inducible expression of CYP isoforms in EpiAirway cultures derived from 4 individual donors. CYP1A1 (weak), CYP1B1, CYP2A6, CYP2B6 (weak), CYP2C8 (weak), CYP2C19, CYP2D6, CYP2E1 and CYP3A5 were expressed constitutively, while CYP3A4 and 3A7 were not detected.
3-Methylcholanthrene (3MC) strongly increased expression of CYP1A1 and slightly increased CYP2B6 and CYP2C8 expression. Thus CYP expression in EpiAirway showed a high concordance with CYP expression reported for in vivo human bronchial epithelium.
Total GST activity in EpiAirway was also evaluated by measuring conjugation of glutathione with 1-chloro-2,4-dinitrobenzene. High baseline GST activity was not further enhanced by 3MC treatment.
The results demonstrate that the EpiAirway in vitro human tracheal/bronchial epithelial model possesses numerous in vivo-like XME activities and may thus be useful for evaluating airway metabolism of drugs, tobacco smoke and environmental/occupational chemicals.
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