Dynamic Calcium Regulation in Airway Smooth Muscle

描述(申请人提供)：哮喘是一种炎症性疾病，其中TH2(如IL-13)和促炎(如TNFa)细胞因子导致呼吸道平滑肌(ASM)功能异常，导致呼吸道高反应性(AHR)，这是该疾病的一个特征。炎症细胞因子改变钙信号和ASM的收缩能力，从而导致对激动剂的高反应性。我们实验室的研究表明，CD38/环状ADP-核糖信号通路在ASM的钙调节中起核心作用，该信号通路受TH2和促炎细胞因子的调控，涉及核因子-β和AP-1的转录机制和转录稳定性。参与这种调控的信号机制是通过激活PI3激酶和丝裂原激活蛋白激酶(MAPK)来实现的。CD38缺乏的小鼠表现出以乙酰甲胆碱反应性减弱为特征的呼吸道表型。这些小鼠的ASM细胞也降低了对激动剂的钙反应。虽然这些观察结果表明CD38参与了正常的呼吸道功能，但它在哮喘病理生理学中的潜在作用仍有待确定。在ASM细胞中，CD38的表达被细胞因子增强，而糖皮质激素，哮喘治疗的主要药物，降低了这种表达。初步结果显示，CD38缺陷小鼠在IL-13或过敏原致敏和激发后AHR减弱。通过骨髓移植将CD38+/+炎性细胞移植到CD38缺陷小鼠体内，使AHR恢复对变应原的攻击。这些研究首次涉及CD38/环状ADP-核糖信号通路在哮喘中的作用，并对CD38在细胞/组织中表达的调节机制提出了生理学意义。本研究的目的是阐明CD38表达调控的信号机制，明确CD38在AHR中的作用。总的假设是，细胞因子通过激活PI3激酶、下游MAPK信号通路以及激活NF-β和AP-1来调节ASM中CD38的表达，而气道常驻细胞中的CD38/环状ADP-核糖信号足以引起炎症反应所致的AHR。糖皮质激素的作用是通过抑制MAPK和转录因子的激活以及转录的稳定性来实现的。在拟议的研究中，我们将确定炎症和TH2细胞因子在ASM中调节CD38的特定机制，以及这些机制在实验性哮喘小鼠模型中的体内意义。这一新信息可能使CD38成为预防和控制哮喘的潜在药理靶点。我们认为，呼吸道中CD38/环状ADP-核糖信号通路的调节剂应该对哮喘等疾病的气道高反应性提供保护。与公共卫生相关。哮喘是一种炎症性疾病，患者对刺激有夸大的呼吸道平滑肌反应。IL-13和TNFa等细胞因子在哮喘发病机制中起核心作用。缺乏CD38蛋白的小鼠不会对细胞因子的攻击产生哮喘反应。我们建议研究CD38在呼吸道中的表达如何受到细胞因子的调节，并建立其在不同哮喘小鼠模型中的作用。这一新信息可能使CD38成为预防和控制哮喘的潜在药理靶点。

DESCRIPTION (provided by applicant): Asthma is an inflammatory disease in which TH2 (such as IL-13) and proinflammatory (such as TNFa) cytokines induce abnormalities of airway smooth muscle (ASM) function that causes airway hyperresponsiveness (AHR), a hallmark of this disease. Inflammatory cytokines alter calcium signaling and contractility of ASM which results in hyperreactivity to agonists. Investigations from our laboratory have provided evidence that the CD38/Cyclic ADP-ribose signaling has a central role in calcium regulation in ASM and this signaling pathway is regulated by TH2 and proinflammatory cytokines through transcriptional mechanisms involving NF-?B and AP-1 and transcript stability. The signaling mechanisms involved in this regulation are mediated by activation of PI3 kinases and Mitogen-activated Protein Kinases (MAPK). Mice deficient in CD38 exhibit an airway phenotype characterized by attenuated methacholine responsiveness. ASM cells from these mice also have reduced calcium responses to agonists. While these observations implicate CD38 in normal airway function, its potential role in the pathophysiology of asthma remains to be determined. In ASM cells, CD38 expression is augmented by cytokines, and glucocorticoids, a mainstay of asthma therapy, decrease this expression. Preliminary results reveal that CD38 deficient mice exhibit attenuated AHR following IL-13 or allergen sensitization and challenge. Reconstitution of CD38+/+ inflammatory cells by bone marrow transfer into CD38 deficient mice restores AHR to allergen challenge. These studies are the first to implicate the CD38/Cyclic ADP-ribose signaling pathway in asthma and bring a physiological significance of the mechanisms of regulation of CD38 expression in cells/tissues outlined in the proposal. The goal of the proposed studies is to delineate the signaling mechanisms involved in the regulation of CD38 expression and to define the role of CD38 in airway smooth muscle cells and inflammatory cells in AHR. The overall hypothesis is that cytokines regulate CD38 expression in ASM through PI3 kinase activation, down-stream MAPK signaling and activation of NF-?B and AP-1, and that the CD38/Cyclic ADP-ribose signaling in airway resident cells is sufficient to cause AHR resulting from the inflammatory response. Glucocorticoid effects are mediated through inhibition of MAPK and transcription factor activation, and transcript stability. In the proposed studies, we will determine specific mechanisms of CD38 regulation by inflammatory and TH2 cytokines in ASM and the in vivo significance of these mechanisms in mouse models of experimental asthma. This new information may identify CD38 as a potential pharmacological target in the prevention and control of asthma. We propose that modulators of the CD38/Cyclic ADP-ribose signaling pathway in the airways should afford protection from airway hyperresponsiveness in diseases such as asthma. PUBLIC HEALTH RELEVANCE. Asthma is an inflammatory disease in which patients have exaggerated airway smooth muscle response to stimuli. Cytokines such as IL-13 and TNFa have a central role in the pathogenesis of asthma. Mice deficient in a protein, CD38, do not develop an asthmatic response to challenges with cytokines. We are proposing to study how the expression of CD38 in the airways is regulated by cytokines and establish its role in different mouse models of asthma. This new information may identify CD38 as a potential pharmacological target in the prevention and control of asthma.