Skin Barrier Adaptation

皮肤屏障适应

• 批准号: 10724505
• 负责人: Cristina de Guzman Strong
• 金额: $ 7.64万
• 依托单位: HENRY FORD HEALTH SYSTEM
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-10 至 2023-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10724505
• 关键词: Skin; Barrier; Adaptation

ABSTRACT The skin epidermis provides a critical first line of environmental defense. However, the mechanisms mediating how epidermal keratinocytes adapt and respond to the external environment are poorly understood. Involucrin (IVL) is the major scaffold protein of the cornified envelope surrounding the differentiated keratinocyte. Our previous work supports a functional role for involucrin in epidermal adaptive responses to the environment, acute microbial exposure, and inflammation. (1) We discovered recent selective sweep for an IVL haplotype in the northern European (CEU) population. This IVL CEU haplotype is associated with increased IVL expression in sun-exposed skin compared to that in non-sun-exposed skin [according to Genotype-Tissue Expression Project (GTEx) data]. Positive selection of IVL CEU is directly correlated with increasingly northern latitudes, suggesting a fitness benefit of increased IVL expression in northern clines. (2) IVL was the only large Epidermal Differentiation Complex (EDC)-encoded skin barrier protein that exhibited significantly higher levels in the epidermis of conventionally raised (CR) lab mice compared to those in germ-free (GF) and reconstituted skin microbiome (RSM) mice (GF mice acutely exposed to CR commensal microbiota), suggesting an adaptive keratinocyte response to microbial interactions. (3) Ivl-/- mouse skin exhibited a protective effect against MC903-induced inflammation with reduced vitamin D receptor expression, suggesting a regulatory role for IVL in vitamin D signaling in the epidermis. We hypothesize that IVL levels are specifically calibrated to generate an adaptive skin barrier that is finely tuned in response to the environment. We will test this hypothesis by performing three aims. Aim 1. Determine the causative genetic variants that increase IVL gene expression levels. IVL CEU includes enhancer 923 that is required for involucrin target gene expression as evidenced by loss of Ivl expression in 923-/- mice. Cellular and molecular assays in keratinocytes will be performed to identify the molecular mechanisms by which enhancer variation(s) modulate target gene expression. Aim 2. Determine the role of involucrin in the skin adaptive response to commensal microbiota. We will examine the skin and inflammatory responses in rederived Ivl-/- CV mice as a functional measurement of skin adaptation. Aim 3. Determine the molecular mechanism by which involucrin regulates Vitamin D receptor expression and signaling in the epidermis. MC903-treated Ivl-/- ear skins did not exhibit severe inflammation and exhibited reduced Vdr expression. We hypothesize a role for Involucrin to positively regulate Vdr expression and signaling via phosphorylated p38δ, a known VDR activator in other human cell types. Our hypothesis will be rigorously tested using constitutively active p38δ and knockdown in vitro studies with anticipated results for increased and decreased Vdr expression and signaling, respectively. This study will identify the molecular mechanisms involved in human skin barrier evolution and adaptation, which can be developed into innovative therapies for treating skin-barrier impaired inflammatory skin diseases.

摘要 皮肤表皮提供了环境防御的关键第一道防线。然而， 表皮角质形成细胞如何适应和响应外部环境还知之甚少。外皮蛋白 (IVL)是围绕分化的角质形成细胞的皮质包膜的主要支架蛋白。我们 以前的工作支持外皮蛋白在表皮对环境的适应性反应中的功能作用， 急性微生物暴露和炎症。(1)我们发现最近的选择性扫描IVL单倍型， 北方欧洲人（CEU）。这种IVL CEU单倍型与IVL表达增加相关 在阳光下暴露的皮肤相比，在非阳光下暴露的皮肤[根据基因型-组织表达 项目（GTEx）数据]。IVL CEU的正选择与越来越高的北方纬度直接相关， 表明在北方品系中IVL表达增加的适合性益处。(2)IVL是唯一一个 表皮分化复合物（EDC）编码的皮肤屏障蛋白， 常规饲养（CR）实验室小鼠的表皮与无菌（GF）和重建的 皮肤微生物组（RSM）小鼠（急性暴露于CR肠道微生物群的GF小鼠），表明适应性 角质形成细胞对微生物相互作用的反应。(3)IVL-/-小鼠皮肤表现出保护作用， MC 903诱导的炎症伴维生素D受体表达减少，提示IVL的调节作用 维生素D在表皮中的信号传导。我们假设IVL水平是专门校准的， 一种适应性皮肤屏障，可以根据环境进行微调。我们将通过以下方式检验这一假设： 实现三个目标。目标1.确定增加IVL基因表达的致病遗传变异 程度. IVL CEU包括增强子923，其是外皮蛋白靶基因表达所需的，如以下所证明的： 923-/-小鼠中IV 1表达的丧失。将在角质形成细胞中进行细胞和分子测定以鉴定 增强子变异调节靶基因表达的分子机制。目标2.确定 外皮蛋白在皮肤对肠道微生物群的适应性反应中的作用我们将检查皮肤， 在再衍生的Ivl-/- CV小鼠中的炎症反应作为皮肤适应的功能测量。目标3. 确定外皮蛋白调节维生素D受体表达的分子机制， 在表皮发出信号。MC 903处理的耳皮肤没有表现出严重的炎症，并且表现出严重的炎症。 减少Vdr表达。我们假设Involucrin的作用是积极调节Vdr的表达， 通过磷酸化p38δ（在其他人类细胞类型中已知的VDR激活剂）进行信号传导。我们的假设是 使用组成型活性p38δ和敲低体外研究进行了严格测试， 分别增加和减少Vdr表达和信号传导。这项研究将确定分子 涉及人类皮肤屏障进化和适应的机制，其可以被开发成创新的 用于治疗皮肤屏障受损的炎性皮肤病的疗法。