RabGEF1 in MyD88 signaling, skin immunity, and atopic dermatitis

RabGEF1 在 MyD88 信号传导、皮肤免疫和特应性皮炎中的作用

• 批准号: 9293893
• 负责人: Stephen Joseph Galli
• 金额: $ 37.29万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-06-01 至 2020-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9293893
• 关键词: Adult; Affect; Allergens; Allergic inflammation; Atopic Dermatitis; Cell Communication; Child; Clinical; Cutaneous; Data; Development; Disease; Distant; Eczema; Family; Goals; Guanine Nucleotide Exchange Factors; Healthcare Systems; Homeostasis; Human; IgE; Immune; Immunity; Impairment; In Vitro; Inflammation; Inflammatory; Italy; Knockout Mice; Lead; Ligands; Lung; Mediating; Medical; Modeling; Molecular; Morbidity - disease rate; Mus; Mutation; Organ; Pathogenesis; Pathology; Pathway interactions; Patients; Permeability; Phenotype; Population; Prevention; Process; Proteins; Public Health; Receptor Activation; Regulation; Role; Route; Serum; Signal Pathway; Signal Transduction; Skin; Source; Specimen; TLR2 gene; TLR4 gene; TLR5 gene; Testing; Text; Toll-like receptors; Work; base; cost; defined contribution; economic impact; environmental agent; immune function; in vivo; insight; keratinocyte; mRNA Expression; mast cell; microorganism; mortality; new therapeutic target; novel strategies; prevent; protein expression; public health relevance; receptor expression; response; skin barrier; skin disorder; skin lesion; skin microbiome; skin microbiota; skin organogenesis; socioeconomics

 DESCRIPTION (provided by applicant): The long-term goal of this project is to understand how the dysregulation of certain keratinocyte functions, by altering the cells' interactions with te skin microbiome, can impair epidermal barrier function, leading to features resembling those of atopic dermatitis (AD) and the development of high serum levels of IgE. Mouse RabGEF1 was discovered as a negative regulator of mast cell activation, and mice globally deficient in RabGEF1 rapidly develop AD-like skin [pathology]. However, conditional deletion of Rabgef1 specifically in mouse keratinocytes is sufficient to drive AD-like skin [pathology] and the development of high levels of serum IgE (as is also seen in AD patients). Moreover, the severe skin disease observed in RabGEF1- deficient mice critically depends on keratinocyte-intrinsic expression of MyD88, an adaptor molecule that mediates signaling by several Toll-like receptors (TLRs). [Expression of RabGEF1 protein] is markedly decreased in lesional skin from patients with AD as compared to healthy skin, whereas MYD88 mRNA expression is significantly increased in lesional skin specimens from AD patients. Since skin is continuously exposed to microorganisms that are a rich source of TLR ligands, we will evaluate to what extent the skin microbiome and keratinocyte TLRs can contribute to the MyD88-dependent AD-like skin [pathology] observed when keratinocytes lack RabGEF1. We will use RabGEF1-deficient mouse and human keratinocytes to analyze in vitro the molecular mechanisms by which RabGEF1 regulates MyD88-dependent signaling pathways. Finally, we will assess how keratinocyte-restricted [complete or partial] reductions in RabGEF1 expression can influence systemic sensitization to allergens via the skin, with the later development of allergic inflammation in distant organs such as the lung. We propose three specific aims to test the General Hypothesis: The development of skin pathology with features of atopic dermatitis, and elevated serum IgE, in RabGEF1-deficient mice reflects the ability of RabGEF1 to maintain skin [barrier and immune] functions by down-regulating pathways initiated by MyD88-dependent signaling in keratinocytes. Aim 1: Define the contributions of MyD88, Toll-like receptors (TLRs), and the skin microflora in the AD-like skin [pathology] induced by keratinocyte-specific Rabgef1 deletion in vivo. Aim 2: Determine the mechanisms by which RabGEF1 negatively regulates MyD88-dependent functional responses and signaling in keratinocytes. Aim 3: Determine the mechanisms by which RabGEF1 deficiency in keratinocytes influences skin sensitization to allergens and the development of the atopic march. This project will clarify how an intrinsic impairment in keratinocyte function due to diminished RabGEF1 can contribute to AD-like skin [pathology]. Ultimately, pursuing such work may enable the discovery of novel therapeutic targets for the prevention or treatment of AD and perhaps other atopic or inflammatory disorders.

 描述（由申请人提供）：该项目的长期目标是了解某些角质形成细胞功能的失调如何通过改变细胞与皮肤微生物组的相互作用来损害表皮屏障功能，从而导致类似于特应性皮炎 (AD) 的特征以及高血清 IgE 水平的发展。小鼠 RabGEF1 被发现是肥大细胞激活的负调节因子，而全面缺乏 RabGEF1 的小鼠会迅速发展出类似 AD 的皮肤[病理学]。然而，在小鼠角质形成细胞中，有条件地删除 Rabgef1 就足以驱动 AD 样皮肤[病理学]和高水平血清 IgE 的发展（在 AD 患者中也可见到）。此外，在 RabGEF1 缺陷小鼠中观察到的严重皮肤病很大程度上取决于 MyD88 的角质形成细胞内在表达，MyD88 是一种通过几种 Toll 样受体 (TLR) 介导信号传导的接头分子。与健康皮肤相比，AD患者病变皮肤中的[RabGEF1蛋白的表达]显着降低，而AD患者病变皮肤标本中MYD88 mRNA的表达显着增加。由于皮肤持续暴露于含有丰富 TLR 配体来源的微生物，因此我们将评估皮肤微生物组和角质形成细胞 TLR 在多大程度上对当角质形成细胞缺乏 RabGEF1 时观察到的 MyD88 依赖性 AD 样皮肤[病理]有贡献。我们将使用 RabGEF1 缺陷的小鼠和人类角质形成细胞来体外分析 RabGEF1 调节 MyD88 依赖性信号通路的分子机制。最后，我们将评估角化细胞限制的 RabGEF1 表达[完全或部分]减少如何影响通过皮肤对过敏原的全身致敏，以及随后在肺部等远处器官中发生过敏性炎症。我们提出了三个具体目标来检验一般假设： RabGEF1 缺陷小鼠中以特应性皮炎为特征的皮肤病理学发展以及血清 IgE 升高反映了 RabGEF1 通过下调角质形成细胞中 MyD88 依赖性信号传导启动的途径来维持皮肤 [屏障和免疫] 功能的能力。目标 1：确定 MyD88、Toll 样受体 (TLR) 和皮肤微生物群在体内角质形成细胞特异性 Rabgef1 缺失诱导的 AD 样皮肤[病理学]中的贡献。目标 2：确定 RabGEF1 负向调节角质形成细胞中 MyD88 依赖性功能反应和信号传导的机制。目标 3：确定角质形成细胞中 RabGEF1 缺乏影响皮肤对过敏原的敏感性和特应性进展的发展的机制。该项目将阐明 RabGEF1 减少导致的角质形成细胞功能的内在损伤如何导致 AD 样皮肤[病理学]。最终，开展此类工作可能会发现预防或治疗 AD 以及其他特应性或炎症性疾病的新治疗靶点。