The Effect of Filaggrin Mutations on Dermal Penetration of Diisocyanates

摘要 美国很大一部分工人可能面临通过以下途径增加接触工业化学品的风险 一种可遗传的缺陷，导致表皮屏障受损。皮肤的主要屏障是 表皮，由形成角化结构(层)的分化角质形成细胞层组成 角质层，SC)。SC的连续性依赖于脂类和结构蛋白的整合基质， 包括丝状胶原蛋白，形成了对外部环境的屏障。屏障的遗传决定因素 人们对诚信知之甚少。人类遗传学研究表明，丝状丝蛋白的完全或部分丢失 表达会降低屏障功能，增加化学物质对皮肤的渗透。这个 丝状丝蛋白对表皮分化和屏障功能的重要性已经在强烈的 微丝蛋白基因(Flg)功能缺失突变与人类慢性皮肤的关系 疾病、寻常型鱼鳞病和特应性湿疹。这些疾病的特征是皮肤干燥和 易患哮喘。这些遗传性皮肤病的严重性和外显性与 可能被其他修饰基因改变的Flg突变(LOF)等位基因的数量。我们已经展示了那张皮肤 暴露于二异氰酸酯，一种已知的呼吸道敏感剂，可能极大地促进全身暴露。 我们假设皮肤中微丝蛋白含量的部分丧失(单倍性不足)将损害屏障功能 导致二异氰酸酯渗透率、剂量和毒性增加。我们建议使用以下方法来检验我们的假设 体外三维(3D)人体器官型皮肤组织，具有和不具有受损的屏障功能。 模型接触剂和呼吸道致敏剂在渗透性和细胞毒性方面的剂量相关差异， 1，6-六亚甲基二异氰酸酯，将在正常和屏障受损的人体皮肤中进行测量 重建。使用屏障折衷人体皮肤重建模型将满足以下重要需求 生物学上相关的方法，以表征化学渗透到表皮，以调查 增加皮肤暴露于皮肤和全身毒性的贡献，并确定个人(易受影响 致敏、过敏和哮喘等不良健康影响的风险增加。这个 拟议的研究代表了一种先进的暴露模型，用于测试二异氰酸酯对人体皮肤的毒性。 此模型测试系统的验证可以提供比目前使用2D测试系统更合适的工具 体外和动物模型研究皮肤暴露于化学呼吸道敏化的作用。AS 因此，建议的研究范围与NIOSH的目标和使命是一致的，并扩大了保护的使命 员工健康。我们有机会为NIOSH研究实践倡议做出贡献，方法是提供 新知识和工具，以确定潜在的易感人群，从而确定干预战略 以及控制以及提供关键数据以通过考虑个体差异来设置暴露限制 这改变了暴露的分类。

ABSTRACT A significant portion of workers in the US could be at risk for an increase in exposure to industrial chemicals via a heritable defect resulting in a compromised epidermal barrier. The primary barrier of the skin is the epidermis, which consists of layers of differentiated keratinocytes forming a cornified structure (stratum corneum, SC). The continuity of the SC is dependent upon an integrated matrix of lipids and structural proteins, including filaggrin, that form a barrier against the external environment. The genetic determinants of barrier integrity are poorly understood. Human genetic studies suggest that the complete or partial loss of filaggrin expression results in decreased barrier function and enhanced penetration of chemicals through the skin. The importance of filaggrin to epidermal differentiation and barrier function has been made evident with the strong association of loss of function (LOF) mutations in the filaggrin gene (FLG) with the chronic human skin diseases, ichthyosis vulgaris and atopic eczema. These diseases are characterized by dry skin and a predisposition to asthma. The severity and penetrance of these heritable skin diseases are correlated with the number of FLG-mutant (LOF) alleles that may be altered by other modifier genes. We have shown that skin exposure to diisocyanates, a known respiratory sensitizer, may significantly contribute to systemic exposure. We hypothesize that partial loss (haploinsufficiency) of filaggrin content in the skin will impair barrier function resulting in increased diisocyanate penetration, dose, and toxicity. We propose to test our hypothesis by using in vitro three-dimensional (3D) human organotypic skin tissues with and without compromised barrier function. The dose-related difference in permeability and cellular toxicity to a model contact and respiratory sensitizer, 1,6-hexamethylene diisocyanate, will be measured in normal and barrier compromised human skin reconstructs. The use of a barrier-compromised human skin reconstruct model will fulfill an important need for biologically relevant methods to characterize chemical penetrance into the epidermis, to investigate the contribution of increased skin exposure to skin and systemic toxicity, and to identify individuals (susceptible subpopulation) at increased risk for adverse health effects, including sensitization, allergy, and asthma. The proposed research represents a cutting-edge exposure model for testing diisocyanate toxicity to human skin. Validation of this model test system can provide a more appropriate tool than is currently available using 2D in vitro and animal models to investigate the role of skin exposure to a chemical respiratory sensitization. As such, the scope of the research proposed is consistent with and amplifies NIOSH goals and mission to protect worker health. We have an opportunity to contribute to the NIOSH Research to Practice initiative by providing new knowledge and tools to identify potential susceptible subpopulations and, thus, strategies for intervention and control as well as to provide critical data to set exposure limits by taking into account individual variation that alter exposure classification.