Characterization of a Structurally Intact in Situ Lung Model and Comparison of Naphthalene Protein Adducts Generated in This Model vs Lung Microsomes

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• 作者：Ching Yu Lin ; Margaret A. Isbell ; Dexter Morin ; Bridget C. Boland ; Michelle R. Salemi ; William T. Jewell ; Alison J. Weir ; Michelle V. Fanucchi ; Gregory L. Baker ; Charles G. Plopper ; and Alan R. Buckpi
• 刊名：Chemical Research in Toxicology
• 出版年：2005
• 出版时间：May 2005
• 年：2005
• 卷：18
• 期：5
• 页码：802 - 813
• 全文大小：908K
• 年卷期：v.18,no.5(May 2005)
• ISSN：1520-5010

文摘

Airway epithelial cells are a susceptible site for injury by ambient air toxicants such asnaphthalene that undergo P450-dependent metabolic activation. The metabolism of naphthalene in Clara cells to reactive intermediates that bind covalently to proteins correlates withcell toxicity. Although several proteins adducted by reactive naphthalene metabolites wereidentified in microsomal incubations, new methods that maintain the structural integrity ofthe lung are needed to examine protein targets. Therefore, we developed a method that involvesinflation of the lungs via the trachea with medium containing ¹⁴C-naphthalene followed byincubation in situ. The viability of this preparation is supported by maintenance of glutathionelevels, rates of naphthalene metabolism, and exclusion of ethidium homodimer-1 from airwayepithelium. Following in situ incubation, the levels of adduct per milligram of protein weremeasured in proteins obtained from bronchoalveolar lavage, epithelial cells, and remaininglung. The levels of adducted proteins obtained in lavage and epithelial cells were similar andwere 20-fold higher than those in residual lung tissue. ¹⁴C-Labeled adducted proteins wereidentified by matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) massspectrometry (MS) and quadrupole-TOF MS/MS. Major adducted proteins include cytoskeletalproteins, proteins involved in folding and translocation, ATP synthase, extracellular proteins,redox proteins, and selenium binding proteins. We conclude that in situ incubation maintainsstructural integrity of the lung while allowing examination of reactive intermediate activationand interaction with target cell proteins of the lung. The proteins adducted and identifiedfrom in situ incubations were not the same proteins identified from microsomal incubations.