Novel strategies for asthma therapy by regulating mast cell signaling by MyD88

描述(申请人提供)：哮喘是一种复杂的呼吸道炎症性疾病，以支气管收缩、呼吸道高反应性和炎症为特征。大量证据表明肥大细胞高亲和力IgE受体(FceRI)在哮喘发病机制中起重要作用。因此，人们已经做出了巨大的努力来了解该受体的功能调节的信号通路。新的证据表明，上皮细胞衍生的细胞因子如白介素33(IL-33)和细菌脂多糖(LPS)通过激活其各自的受体ST2和TLR4在哮喘加重中发挥重要作用，但其作用机制尚不清楚。髓系分化因子(Myd)88是最近端传递IL-33和内毒素信号的适配分子。我们发现，MyD88不仅能调节肥大细胞中的IL-33和内毒素信号，还能促进抗原/IgE介导的蛋白激酶B(Akt)的磷酸化和细胞因子的产生。我们还发现，内毒素或IL-33与抗原/IgE协同产生细胞因子，并且在MyD88-/-肥大细胞中这种串扰几乎被消除。基于这些发现，我们假设MyD88通过调节和交叉调节肥大细胞中的Fc5RI信号来促进过敏性炎症。为进一步探讨MyD88在肥大细胞信号转导和体内过敏性炎症小鼠模型中的作用，提出了两个具体的目标。在目标1中，我们将利用逆转录病毒将野生型或转基因MyD88导入MyD88-/-肥大细胞，以描述该接头分子如何调节和交叉调节肥大细胞中的FceRI信号。在第二个目标中，我们将首先测试在体内肥大细胞中表达的MyD88介导变态反应性炎症的假设。然后，我们将对肥大细胞中的MyD88信号进行调制，并确定这种调制对过敏性炎症的影响。我们相信，拟议的研究将在肥大细胞中FceRI信号的调节和交叉调节方面产生重要的新信息，并可能为哮喘和其他过敏性疾病的治疗提供新的治疗方法。公共卫生相关性：哮喘是一种复杂的呼吸道炎症性疾病，以支气管收缩、呼吸道高反应性和炎症为特征。据估计，大约有1700万美国人患有哮喘，其中三分之一是儿童。近年来，哮喘的患病率和严重程度在全球范围内急剧上升。肥大细胞释放炎症介质，导致哮喘和其他过敏性疾病的症状。这一建议是基于发现了一种调节肥大细胞功能的新分子。我们相信，拟议的研究将在肥大细胞功能调节方面产生重要的新信息，并可能为哮喘和其他过敏性疾病的治疗提供新的治疗方法。

DESCRIPTION (provided by applicant): Asthma is a complex airway inflammatory disease characterized by bronchoconstriction, airway hyperresponsiveness and inflammation. There is a substantial body of evidence that demonstrates an important role for mast cell high affinity IgE receptor (FceRI) in the pathogenesis of asthma. Therefore, tremendous efforts have been directed towards understanding the signaling pathway via which function of this receptor is regulated. Emerging evidence suggests that epithelial cell-derived cytokine such as interleukin-33 (IL-33) and bacterial lipopolysaccharide (LPS) play important roles in asthma exacerbation via the activation of their respective receptors ST2 and TLR4 but the mechanisms of their action remains unknown. Myeloid differentiation factor (MyD) 88 is the most proximal adapter molecule that transmits signal for both IL-33 and LPS. We made the novel observation that MyD88 not only regulates IL-33 and LPS signaling in mast cells, it also contributes to antigen/IgE-mediated protein kinase B (Akt) phosphorylation and cytokine production. We also found that LPS or IL-33 synergizes with antigen/IgE for cytokine generation and that this cross-talk is almost abolished in MyD88-/- mast cells. Based on these findings, we hypothesize that MyD88 promotes allergic inflammation by regulating and cross-regulating Fc5RI signaling in mast cells. Two specific aims are proposed to further explore the role of MyD88 on mast cell signaling in vitro and murine model of allergic inflammation in vivo. In aim #1, we will use retrovirus to transfect MyD88-/- mast cells with wild-type or genetically modified MyD88 to delineate how this adapter molecule regulates and cross-regulates FceRI signaling in mast cells. In aim #2, we will first test the hypothesis that MyD88 expressed in mast cells mediates allergic inflammation in vivo. We will then modulate MyD88 signaling in mast cells and determine the impact of this modulation on allergic inflammation. We believe that proposed studies will generate significant new information on the regulation and cross-regulation of FceRI signaling in mast cells and may offer novel therapeutic approaches for the treatment of asthma and other allergic diseases. PUBLIC HEALTH RELEVANCE: Asthma is a complex airway inflammatory disease characterized by bronchoconstriction, airway hyperresponsiveness and inflammation. Approximately 17 million Americans are estimated to have asthma, one third of them children. In recent years, asthma prevalence and severity have been increasing dramatically world-wide. Mast cells release inflammatory mediators that cause the symptoms of asthma and other allergic diseases. This proposal is based on the identification of a new molecule that regulates mast cell function. We believe that proposed studies will generate significant new information on the regulation of mast cell function and may offer novel therapeutic approaches for the treatment of asthma and other allergic diseases.