c-Ab1 in the allergic inflammatory lung disease

描述(申请人提供)：辅助性T细胞2型(Th2)细胞通过产生关键的细胞因子，包括白介素4、白介素5和白介素13，在引起过敏性炎症性肺部疾病如哮喘中起关键作用。在特定抗原的刺激下，初始的CD4+T细胞分化为Th1或Th2的分子机制仍然知之甚少。在这里，我们的初步研究表明，c-Abl是一种Src家族酪氨酸激酶，其功能的丧失使CD4+T细胞向Th2分化，因为与c-Abl+/+CD4+T细胞产生这些Th2细胞因子相比，c-Abl-/-CD4+T细胞产生IL-4、IL-5和IL-13的能力显著增加。而c-Abl-/-CD4+T细胞产生Th1细胞因子的能力受到抑制。有趣的是，我们发现在c-Abl-/-T细胞中，Th1-linage转录因子T-bet的酪氨酸磷酸化水平显著降低，这表明c-Abl通过磷酸化T-bet来调节Th1/Th2分化。为了支持这一点，我们发现c-Abl的过度表达而不是它的激酶死亡突变体诱导了T-bet的酪氨酸磷酸化。Jurkat T细胞表达c-Abl激活干扰素？记者活动和抑制IL-4记者。这些结果表明，c-Abl通过激活T-bet来维持Th1和Th1分化之间的平衡，c-Abl功能的丧失增强了Th1，但损害了Th1的分化。因此，c-Abl缺乏可能会引起小鼠的过敏性肺部炎症。我们将通过解决以下两个具体目标来验证这一假说：目的1.c-Abl如何调节Th1/Th2分化？C-Abl磷酸化从而激活Th1系转录因子T-bet的事实表明，c-Abl通过靶向T-bet来调节Th1/Th2的分化。我们将进一步研究c-Abl是如何调节T-bet转录活性的。除了T-bet外，其他几种转录因子和信号分子也参与调节CD4+辅助细胞的分化；因此，我们还将确定c-Abl是否通过靶向其他分子来调节T细胞的分化。目的2.c-Abl缺乏会导致小鼠哮喘吗？Th2细胞因子，特别是IL-4和IL-13，在小鼠和人类哮喘的发生发展中起着至关重要的作用。C-Abl-/-CD4+T细胞产生Th2细胞因子上调的事实表明，c-Abl-/-小鼠可能发生哮喘。我们将使用一个实验性哮喘模型来确定c-Abl缺乏如何影响：1.呼吸道阻力，2.IgE的产生，3.呼吸道炎症和炎性细胞的迁移，以及4.呼吸道高反应性。我们预计c-Abl-/-小鼠比野生型小鼠发生更严重的过敏反应。与公共健康相关：大约有1000万美国人患有哮喘，这是美国最常见、最昂贵的疾病之一(每年的医疗费用超过180亿美元)。过敏性哮喘是最常见的哮喘形式，它是由Th2细胞因子产生增加引起的。我们拟议的研究结果应该会揭示一个以前未知的调节Th2细胞因子产生的机制。此外，c-Abl作为一种调节因子可能成为控制哮喘等疾病的过敏性炎症的潜在治疗靶点。

DESCRIPTION (provided by applicant): T helper type 2 (Th2) cells are crucial for causing the allergic inflammatory lung diseases such as asthma, by producing key cytokines, including interleukin (IL)-4, IL-5 and IL-13. The molecular mechanisms that mediate naive CD4+ T cells, after they are stimulated by specific antigens, to differentiate into Th1 or Th2 are still poorly understood. Here, our preliminary studies have demonstrated that loss of the functions of c-Abl, a Src family tyrosine kinase, skews CD4+ T cells to Th2 differentiation because the production of IL-4, IL-5 and IL-13 by c-Abl-/- CD4+ T cells is dramatically increased when compared to the production of these Th2 cytokines by c-Abl+/+ CD4+ T cells. While the production of Th1 cytokines from c-Abl-/- CD4+ T cells was impaired. Interestingly, we found that the tyrosine phosphorylation of Th1-linage transcription factor, T-bet, is dramatically reduced in c-Abl-/- T cells, suggesting that c-Abl regulates Th1/Th2 differentiation by, at least one of the mechanisms, phosphorylating T-bet. To support this, we found that over-expression of c-Abl but not its kinase-dead mutant, induced the tyrosine phosphorylation of T-bet. Expression of c-Abl in Jurkat T cells activates IFN? reporter activity and suppresses IL-4 reporters. These results indicate that c-Abl keeps the balance between Th1 and Th1 differentiation by activating T-bet, and loss of c-Abl functions enhances Th1 but impairs Th1 differentiation. Therefore, c-Abl-deficiency may cause allergic lung inflammations in mice. We will test this hypothesis by addressing the following two Specific Aims: Aim 1. How does c-Abl regulate Th1/Th2 differentiation? The fact that c-Abl phosphorylates, and thereby activates the Th1-lineage transcriptional factor T-bet, indicates that c-Abl regulates Th1/Th2 differentiation by targeting T-bet. We will further examine how T-bet transcription activity is regulated by c-Abl. Besides T-bet, several other transcription factors and signaling molecules are also involved in regulating CD4+ helper cell differentiation; thus, we will also determine whether c-Abl regulates T cell differentiation by targeting other molecules. Aim 2. Does c-Abl-deficiency cause asthma in mice? Th2 cytokines, particularly IL-4 and IL-13, plays a crucial role in asthma development in mice as well as in humans. The fact that the production of Th2 cytokines by c-Abl-/- CD4+ T cells is upregulated suggests that c-Abl-/- mice may potentially develop asthma. We will use an experimental asthma model to determine how c-Abl deficiency affects: 1. the airway resistance, 2. the IgE production, 3. the airway inflammation and the migration of inflammatory cells and 4. airway hyperresponsiveness. We anticipate that c-Abl-/- mice develop more severe allergic responses than wild-type mice. PUBLIC HEALTH RELEVANCE: About 10 million Americans have asthma, one of the most common and costly (over $18 billion annual health care costs) illnesses in the United States. Allergic asthma is the most common form of asthma, which is caused by elevated Th2 cytokine production. The results from our proposed research should uncover a previously unknown mechanism in regulating Th2 cytokine production. Further, c-Abl as a regulator might be a potential therapeutic target for controlling allergic inflammation in diseases such as asthma.