Comparative Toxico-Genomics and Individual Differences in Response to Dermal PAH

关于皮肤中异物暴露、摄取和新陈代谢的个体差异以及暴露对个体健康影响的潜在价值的了解是有限的。这降低了我们调查影响皮肤暴露的个别因素之间的相关性的能力，并限制了皮肤暴露评估的使用及其与来自其他途径的全身暴露的关系，从而影响了整体暴露评估。我们建议检验几个假设：(1)有活力的表皮的角质形成细胞通过细胞色素P450加氧酶的诱导将多环芳烃(PAH)代谢成亲电体，细胞色素P450加氧酶与在分化和成熟过程中表达的角蛋白的亲核残基相加；(2)多环芳烃暴露于表皮会导致基因和 (3)多环芳烃诱导的表皮基因表达变化与暴露水平有关，因此可以预测多环芳烃暴露剂量反应的个体差异。我们将确定和表征重建的人类表皮和人类皮肤细胞对多环芳烃暴露的反应。具体地说，我们将确定表达代谢多环芳烃的第一相和第二相酶的细胞，以及可能改变个体对多环芳烃暴露的反应的环境响应基因。其次，我们将确定暴露于已知水平多环芳烃的重建表皮中多环芳烃亲电加合物角蛋白的浓度是否与多环芳烃暴露呈剂量反应关系。 角蛋白加合物是否可用作真皮的定量生物标志物 暴露于多环芳烃。第三，我们将确定表皮中对多环芳烃暴露反应至关重要的基因和蛋白质表达模式，以及与暴露水平相关的数量差异，从而预测个体差异。最后，在观察到有统计学意义的个体差异的地方，我们将对可能导致这些数量差异的环境响应基因的等位基因差异的候选基因进行分型。人类群体中可能存在的对多环芳烃暴露和大分子内收和/或损伤的个体新陈代谢和表皮基因表达的潜在显著差异，需要表征和纳入。 纳入暴露和风险评估模型。通过这些拟议的研究获得的结果将增加我们对皮肤暴露的作用以及皮肤和内部组织接受的内部剂量的了解。

Knowledge of individual differences in xenobiotic exposure, uptake, and metabolism in the skin, and the potential value for exposure assessment of individual health effects is limited. This reduces our ability to investigate the correlation between individual factors that affect dermal exposure and limits the use of dermal exposure assessment and its relationship to systemic exposure from other routes, compromising overall exposure assessment. We propose to test several hypotheses: (1) keratinocytes of the viable epidermis metabolize polycyclic aromatic hydrocarbons (PAH) to electrophiles through the induction of the cytochrome P450 oxygenases that adduct nucleophilic residues of keratin expressed during differentiation and maturation, (2) PAH exposure to the epidermis results in an individual pattern of expression of genes and their corresponding proteins; (3) PAH induced changes in gene expression in the epidermis correlate with exposure level and, thus, can predict individual differences in the dose response to PAH exposure. We will determine and characterize the response in the reconstructed human epidermis and human skin cells to PAH exposure. Specifically, we will identify the cells that express phase 1 and phase 2 enzymes, which metabolize PAH, and the environmentally responsive genes which may modify individual response to the PAH exposure. Secondly, we will determine if the concentration of PAH-electrophile adducted keratin in reconstructed epidermis exposed to known levels of PAH correlates with PAH exposure in a dose-responsive manner and establish if keratin adducts may be used as quantitative biomarkers of dermal exposure to PAH. Third, we will determine the pattern of gene and protein expression in the epidermis that are critical to PAH-exposure response and to quantitative differences in response to exposure levels that correlate, and, thus, predict individual differences. Finally, where statistically significant individual differences are observed, we will genotype candidate genes for allelic differences in environmentally responsive genes that may be responsible for these quantitative differences. The potential significant differences in individual metabolism and gene expression in the epidermis in response to PAH exposure and macromolecule adduction and/or damage, which may exist in the human population, require characterization and inclusion into exposure and risk assessment models. The results obtained by these proposed studies will increase our knowledge of the role of dermal exposure and the internal dose received to both the skin and internal tissues.