Department of Anatomy, Physiology and Cell Biology, Center for Comparative Respiratory Biology and Medicine, School of Veterinary Medicine and Center for Health and the Environment, University of California at Davis, Davis, California.
Pharmacology and Toxicology Department, College of Pharmacy, University of Arizona, Tucson, Arizona.
Am J Physiol Lung Cell Mol Physiol. 2022 Sep 1;323(3):L308-L328. doi: 10.1152/ajplung.00349.2021. Epub 2022 Jul 19.
The translational value of high-throughput toxicity testing will depend on pharmacokinetic validation. Yet, popular in vitro airway epithelia models were optimized for structure and mucociliary function without considering the bioactivation or detoxification capabilities of lung-specific enzymes. This study evaluated xenobiotic metabolism maintenance within differentiated air-liquid interface (ALI) airway epithelial cell cultures (human bronchial; human, rhesus, and mouse tracheal), isolated airway epithelial cells (human, rhesus, and mouse tracheal; rhesus bronchial), and ex vivo microdissected airways (rhesus and mouse) by measuring gene expression, glutathione content, and naphthalene metabolism. Glutathione levels and detoxification gene transcripts were measured after 1-h exposure to 80 µM naphthalene (a bioactivated toxicant) or reactive naphthoquinone metabolites. Glutathione and glutathione-related enzyme transcript levels were maintained in ALI cultures from all species relative to source tissues, while cytochrome P450 monooxygenase gene expression declined. Notable species differences among the models included a 40-fold lower total glutathione content for mouse ALI trachea cells relative to human and rhesus; a higher rate of naphthalene metabolism in mouse ALI cultures for naphthalene-glutathione formation (100-fold over rhesus) and naphthalene-dihydrodiol production (10-fold over human); and opposite effects of 1,2-naphthoquinone exposure in some models-glutathione was depleted in rhesus tissue but rose in mouse ALI samples. The responses of an immortalized bronchial cell line to naphthalene and naphthoquinones were inconsistent with those of human ALI cultures. These findings of preserved species differences and the altered balance of phase I and phase II xenobiotic metabolism among the characterized in vitro models should be considered for future pulmonary toxicity testing.
高通量毒性测试的转化价值将取决于药代动力学验证。然而，常用的体外气道上皮模型是针对结构和黏液纤毛功能进行优化的，而没有考虑到肺特异性酶的生物活化或解毒能力。本研究通过测量基因表达、谷胱甘肽含量和萘代谢，评估了分化的气液界面（ALI）气道上皮细胞培养物（人支气管；人、恒河猴和鼠气管）、分离的气道上皮细胞（人、恒河猴和鼠气管；恒河猴支气管）和离体微切割气道（恒河猴和鼠）中外源生物代谢的维持情况。在用 80µM 萘（一种生物活化的毒物）或反应性萘醌代谢物处理 1 小时后，测量了谷胱甘肽水平和解毒基因转录物。与来源组织相比，所有物种的 ALI 培养物中的谷胱甘肽水平和解毒相关酶的转录物水平均得到维持，而细胞色素 P450 单加氧酶基因表达下降。模型之间的显著物种差异包括：与人和恒河猴相比，鼠 ALI 气管细胞的总谷胱甘肽含量低 40 倍；与恒河猴相比，鼠 ALI 培养物中萘的代谢率更高，形成萘-谷胱甘肽的速率（比恒河猴高 100 倍）和形成萘二醇的速率（比人高 10 倍）；1,2-萘醌暴露在某些模型中的作用相反-在恒河猴组织中耗尽谷胱甘肽，但在鼠 ALI 样本中增加。永生化支气管细胞系对萘和萘醌的反应与人类 ALI 培养物的反应不一致。这些发现表明，在体外模型中保留了物种差异，以及 I 相和 II 相外源生物代谢的平衡发生改变，在未来的肺毒性测试中应予以考虑。
