SIGNAL TRANSDUCTION IN SENSITIZED AIRWAY SMOOTH MUSCLE

描述：本研究旨在检查夸大的气道 狭窄反应和受损的β-肾上腺素受体抑制反应， 人类哮喘模型。 考虑到细胞内关键的第二个 信使，IP 3在调节气道平滑肌（ASM）收缩性， 以及某些促炎细胞因子在介导炎症反应中的作用。 特应性/哮喘状态，提出了两个相互关联的假设：1. 变化 在收缩激动剂和β-肾上腺素受体介导的反应性中， 特应性/哮喘ASM归因于改变的受体偶联蓄积 和/或IP 3的作用;以及2. 这些变化的诱导， 跨膜信号调节ASM反应性与Fc有关 受体偶联的自分泌释放和ASM中特异性细胞因子的作用。 在解决这些假设，机制调节收缩，受体 和G蛋白表达、第二信使激活和细胞因子 将在分离的兔和人ASM中检测其表达和作用 组织和培养的ASM细胞被动致敏的人 特应性/哮喘血清。 研究ASM改变的潜在机制 在致敏状态下的收缩性，研究人员将检查 1）IP 3的激动剂/受体偶联蓄积; 2）表达的变化 和特定G蛋白的调节作用;和3）代谢和 IP 3与其Ca 2+动员细胞内受体的结合。 到 研究减弱β-肾上腺素受体偶联 在致敏ASM的松弛，研究人员建议检查变化 1）β-肾上腺素能特异性G蛋白表达和调节 受体结合和转导;和2）β-肾上腺素受体/G蛋白偶联 收缩肌激动剂诱导的IP 3积累的调节， 代谢及其受体结合。 最后，为了解决自分泌 细胞因子在诱导ASM反应性改变中的作用 特应性/哮喘致敏状态，研究者将检查1） ASM的特应性致敏诱导自分泌表达和作用， 特异性细胞因子; 2）后者是由于激活 ASM细胞上内源性上调的Fc受体;和3）精氨酸诱导的 ASM反应性的变化反映了以下因素的影响 上述目标下所述的单独机制。 总的来说，这些研究应该产生重要的新见解， ASM在Fc与细胞因子之间的相互作用机制中的潜在自分泌作用 受体活化、细胞因子活化和改变的跨膜 导致特应性/哮喘患者ASM反应性改变的信号传导 敏化态

DESCRIPTION: This investigation proposes to examine the exaggerated airway narrowing response and impaired beta-adrenoceptor inhibitory response in a model of human asthma. Given the role of the key intracellular second messenger, IP3 in regulating airway smooth muscle (ASM) contractility, as well as the role of certain pro-inflammatory cytokines in mediating the atopic/asthmatic state, two interrelated hypotheses are raised: 1. Changes in constrictor agonists and beta-adrenoceptor mediated responsiveness in atopic/asthmatic ASM are attributed to altered receptor coupled accumulation and/or action of IP3; and 2. The induction of these changes in transmembrane signaling regulation ASM responsiveness is related to Fc receptor-coupled autocrine release and action of specific cytokines in ASM. In addressing these hypotheses, mechanism regulating contractility, receptor and G protein expression, second messenger activation, and cytokine expression and action will be examined in isolated rabbit and human ASM tissue and cultured ASM cells passively sensitized with human atopic/asthmatic serum. To investigate mechanisms underlying altered ASM contractility in the sensitized state, the investigators will examine changes in 1) agonist/receptor-coupled accumulation of IP3; 2) expression and modulatory action of specific G proteins; and 3) the metabolism and binding of IP3 to its Ca2+ mobilizing intracellular receptor. To investigate mechanisms underlying attenuated beta-adrenoceptor-coupled relaxation in sensitized ASM, the investigators propose to examine changes in 1) specific G protein expression and regulation of beta-adrenergic receptor biding and transduction; and 2) beta-adrenoceptor/G protein-coupled modulation of constrictor agonist-induced accumulation on IP3, its metabolism, and its receptor binding. Finally, to address the autorcrine role of cytokines in inducing altered ASM responsiveness in the atopic/asthmatic sensitized state, the investigators will examine whether 1) atopic sensitization of ASM induces the autocrine expression and action of specific cytokines; 2) the latter is attributed to activation of endogenously upregulated Fc receptors on ASM cells; and 3) cytokine-induced changes in ASM responsiveness reflect alterations in the contributions of the separate mechanisms delineated above under objectives cited above. Collectively, these studies should yield important new insights into the potential autocrine role of ASM in the mechanistic interplay between Fc receptor activation, cytokine activation, and altered transmembrane signaling contributing to altered ASM responsiveness in the atopic/asthmatic sensitized state.