The role of TRAF4 E3 ligase in IL-25-mediated allergic asthma

项目概要/摘要： 大约一半的过敏性哮喘患者由于增加的2型T细胞亚群而被归类为Th 2-高（相对于Th 2-低）内源型。 与健康对照组相比。气道2型炎症，以Th 2增加为特征 (type 2）细胞因子（IL-4、IL-5、IL-9、IL-13），由肺的多种细胞类型之间的相互作用介导， 包括结构细胞（例如上皮细胞）和浸润细胞（例如Th 2细胞、第2组先天淋巴样细胞 （ILC2s））。虽然大多数Th 2高哮喘患者对目前的类固醇治疗有反应，但值得注意的是， 具有这种内型的患者亚组显示出类固醇抗性，并需要高剂量的类固醇来控制其 持续的症状因此，对于开发新的类固醇节省疗法以减少激素依赖存在未满足的需求。 大剂量使用类固醇的副作用白细胞介素（IL）-25（也称为IL-17 E）已经被广泛应用于治疗和预防癌症。 被认为是经典Th 2应答的重要上游调节因子。单核苷酸多态性 (SNP)IL-25受体（IL-25 R）亚单位IL-17 RB的表达与哮喘的风险有关，这表明靶向IL-17 RB的表达可能与哮喘的发生有关。 25可能在哮喘患者的一个子集中具有临床意义。我们以前确定Act 1（TRAF 3 IP 2）是一种 IL-25信号转导中的必需衔接分子，并确定其在IL-25介导的过敏性肺 炎症令人兴奋的是，我们最近发现TNF受体相关因子4（TRAF 4）是一种新的 介导Act 1向IL-25 R募集的信号分子，对IL-25发挥关键功能作用， 介导的气道炎症。TRAF 4蛋白的RING结构域是赋予蛋白质 具有E3连接酶活性。我们和其他人已经表明TRAF 4是一种真正的E3连接酶， 泛素化是通过其RING指结构域的多聚泛素化和其结合配偶体的泛素化来实现的。我们因此 假设TRAF 4在IL-25信号传导中作为E3连接酶发挥作用，影响Act 1依赖性和 以细胞特异性方式通过独立途径促进2型过敏性哮喘。为了验证这个假设，我们 本研究提出以下具体目的：1）研究TRAF 4在不同细胞中的内在作用 2）阐明TRAF 4介导的IL-12表达的分子机制。 25信号建议对IL-25信号转导中TRAF 4 E3连接酶进行深入的细胞和分子研究 将提供对引发和维持哮喘表型的事件的重要见解。而且 我们提出的研究结果可能会提高识别新药物靶点和开发新药物的潜力。 用于治疗哮喘的类固醇节省药物（例如靶向IL-25信号传导的途径特异性诱饵肽）。

Project Summary/Abstract: Around half of allergic asthmatics are classified as Th2-high (vs. Th2-low) endotype due to increased type 2 inflammation as compared with healthy controls. Airway type 2 inflammation, characterized by increased Th2 (type 2) cytokines (IL-4, IL-5, IL-9, IL-13), is mediated by interplays between multiple cell types of the lung, including structural cells (e.g. epithelial cells), and infiltrating cells (e.g. Th2 cells, group 2 innate lymphoid cells (ILC2s)). Although most of Th2-high asthmatics are responsive to current steroid-based therapy, a notable subgroup of patients with this endotype show steroid-resistance and require high-dose steroids to control their persistent symptoms. Therefore, there is an unmet need for developing novel steroid-sparing therapy to reduce the side effects associated with high-dose use of steroids. Interleukin (IL)-25 (also called IL-17E) has been known as an important upstream regulator of the classic Th2 response. The single-nucleotide polymorphism (SNP) of IL-25 receptor (IL-25R) subunit IL-17RB has been linked to risk of asthma, implicating that targeting IL- 25 may be of clinical significance in a subset of asthmatics. We previously identified Act1 (TRAF3IP2) as an essential adaptor molecule in IL-25 signaling and established its critical role in IL-25-mediated allergic pulmonary inflammation. Excitingly, we recently found that TNF receptor associated factor 4 (TRAF4) was a novel signaling molecule meditating Act1 recruitment to IL-25R, exerting a critical functional role for IL-25- mediated airway inflammation. The RING domain of TRAF4 protein is a structural feature that confers protein with E3 ligase activity. We and others have shown that TRAF4 is a genuine E3 ligase which induces polyubiquitination and the ubiquitination of its binding partners through its RING finger domain. We thus hypothesize that TRAF4 functions as an E3 ligase in IL-25 signaling impacting both Act1-dependent and - independent pathways in a cell-specific manner to promote type 2 allergic asthma. To test this hypothesis, we propose the following Specific Aims: 1) Investigate the intrinsic role of TRAF4 in different cell compartments in type 2 allergic asthma; 2) Delineate the molecular mechanism of TRAF4-mediated IL- 25 signaling. The proposed in-depth cellular and molecular studies on the TRAF4 E3 ligase in IL-25 signaling will provide significant insight into the events that initiate and maintain the asthmatic phenotype. Moreover, the results from our proposed studies may improve the potential to identify new drug targets and develop novel steroid-sparing drugs (e.g pathway-specific decoy peptides targeting IL-25 signaling) for treatment of asthma.