Role of cAMP specific phosphodiesterase in asthma

(申请人摘要)易患过敏性炎症性疾病， 包括哮喘，是由一组复杂的基因决定的，这些基因有助于 呼吸道功能和炎症的调节。增加的代理 细胞内cAMP对信号转导有明显的抑制作用 控制致炎细胞和呼吸道平滑肌功能的通路。 CAMP升高与气道平滑肌抑制有关 收缩，T细胞激活，以及迁移和/或功能 存在于过敏性炎症部位的效应细胞，例如 肥大细胞、嗜酸性粒细胞和嗜碱性粒细胞。在这里，我们将检验假设 编码环磷酸腺苷特异性磷酸二酯酶(PDE4)的基因，组成 CAMP信号级联，是变应原诱导的呼吸道的主要决定因素 高反应性(AHR)。在人类和其他生物中存在的四种PDE4基因 哺乳动物(PDE4A、B、C和D)、三种(A、B和D)在呼吸道中表达 以及炎性细胞中。我们已经建立了活体模型，在这些模型中 PDE4基因已通过同源重组失活，并显示出 变应原诱导的AHR在纯合子为空的小鼠中不会发生 其中两个基因(PDE4B或PDE4D)。这些发现表明，这些 PDE和它们所服务的信令功能在 哮喘的一个标志--AHR的发病机制。然而，虽然PDE4B-/-和 PDE4D-/-小鼠表现出过敏原诱导的AHR消失，只有PDE4D-/-小鼠表现出 基线时对胆碱能刺激无呼吸道反应。这 这一发现有力地表明，AHR表型的细胞基础 两只突变小鼠可能是截然不同的。我们现在建议用这些活体小鼠 详细定义PDE调节和cAMP动态平衡如何 影响呼吸道平滑肌和促炎细胞的生物学。 利用这些体内模型，我们将研究PDE4是如何 同工酶，更广泛地说，cAMP信号，可以影响，a) 炎症细胞的分化和向肺部的重新募集，以及b) 发展哮喘的特殊特征，包括AHR。这些 在哮喘小鼠模型上的实验将使我们能够测试这个概念 人群中存在的PDE4等位基因的多态/突变 与易患过敏性哮喘的遗传背景有关。他们 还将为开发一类新的 用于治疗哮喘和其他炎症性疾病的药物。

(Applicant's Abstract) The susceptibility to allergic inflammatory diseases, including asthma, is determined by a complex set of genes that contribute to the regulation of airway function and inflammation. Agents that increase intracellular cAMP have predominantly inhibitory effects on the signaling pathways that control pro-inflammatory cell and airway smooth muscle function. An increase in cAMP is associated with the inhibition of airway smooth muscle contraction, T cell activation, and the migration and/or function of the effector cells that are present in sites of allergic inflammation, such as mast cells, eosinophils, and basophils. Here, we will test the hypothesis that genes coding for cyclic AMP-specific phosphodiesterases (PDE4s), components of the cAMP signaling cascade, are major determinants of allergen-induced airway hyperreactivity (AHR). Of the four PDE4 genes present in humans and other mammals (PDE4A, B, C, and D), three (A, B, and D) are expressed in the airway and in inflammatory cells. We have established in vivo models in which these PDE4 genes have been inactivated by homologous recombination, and have shown that allergen-induced AHR does not develop in mice homozygous null for either of two of these genes (PDE4B or PDE4D). These findings indicate that these PDEs, and the signaling functions they serve, play an essential role in the pathogenesis of AHR, a hallmark of asthma. However, while both PDE4B -/- and PDE4D -/- mice exhibit loss of allergen-induced AHR, only PDE4D -/- mice exhibit no airway responsiveness to cholinergic stimulation at baseline. This finding strongly suggests that the cellular basis of the AHR phenotypes in the two mutant mice may be distinct. We now propose to use these in vivo mouse models to define in detail how PDE regulation and cAMP homeostasis can influence the biology of the airway smooth muscle and pro-inflammatory cells. Taking advantage of these in vivo models, we will investigate how PDE4 isoenzymes and, more generally, cAMP signaling, can influence, a) the differentiation and recruitment of inflammatory cells to the lungs, and b) the development of specific characteristics of asthma, including AHR. These experiments in mouse models of asthma will permit us to test the concept that polymorphisms/mutations in the PDE4 alleles present in the human population contribute to the genetic background predisposing to allergic asthma. They will also provide "proof of concept" for the development of a new class of drugs useful for the treatment of asthma and other inflammatory disorders.