Regulation of mediator release from human mast cell by extracellular adenosine.

描述（由申请人提供）： 该提案旨在建立成熟人类肥大细胞上G蛋白偶联腺苷受体（ADOR）和Fce/yR之间的分子联系，以帮助解释腺苷对人类过敏性疾病（如哮喘）的影响。细胞外腺苷（extADO）是一种嘌呤核苷，当吸入时会引起支气管痉挛，并增强人哮喘（但不是正常）气道中肥大细胞的脱粒。因此，它与哮喘发病机制有关。四个G蛋白偶联腺苷受体（A1 AR，A2 aAR，A2 bAR和A3 AR）已被鉴定和表征。然而，负责extADO对人气道肥大细胞的作用的ADOR尚不清楚，尽管间接证据表明A2 bAR参与其中。已经描述了两种类型的人肥大细胞，MCTC和MCT。来自皮肤的MCTC细胞表达类胰蛋白酶、糜蛋白酶、羧肽酶A3和组织蛋白酶G;而MCT细胞仅表达类胰蛋白酶，并且是肺中的主要类型。我们的初步数据显示，高extADO（10-4 M）抑制FceRI介导的MCTC（皮肤）肥大细胞的脱粒，而低extADO（10-7 M）增加MCT（肺）肥大细胞的介质释放。因此，表明extADO差异调节介质从这些不同类型的人肥大细胞释放。extADO还增加IL-13（一种与哮喘发病机制有关的Th 2细胞因子）的分泌，但抑制MCTC细胞产生PGD 2、TNF α、GM CSF和IL 6，并抑制NF-κ B活化。所提出的研究将表征extADO对从通过FceRI以及FcyRlla激活的MCTC和MCT类型的肥大细胞释放介质的影响，FcyRlla是本实验室最近发现的一种激活IgG受体，其在皮肤MCTC上组成型表达，并且可能在肺MCT细胞上组成型表达，并鉴定负责观察到的对这两种类型的人肥大细胞的对比效应的ADOR。Syk激酶和src酪氨酸激酶Fyn和林恩（FceRI依赖性脱粒的关键调节因子）将作为MCTC和MCT肥大细胞中ADOR信号的靶标进行分析。NF-κ B活化的抑制也将作为IL-13产生的一般机制进行评估。过敏和哮喘是美国的主要健康问题。了解这些疾病的细胞成分和调节这些细胞类型的分子机制是我们减轻这些疾病造成的个人和社会负担的主要兴趣。(End摘要）

DESCRIPTION (provided by applicant): This proposal aims to establish a molecular link between G protein-coupled adenosine receptors (ADORs) and Fce/yRs on mature human mast cells to help explain the impact of adenosine on human allergic diseases such as asthma. Extracellular adenosine (extADO) is a purine nucleoside that when inhaled causes bronchospasm and enhances degranulation of mast cells in human asthmatic (but not in normal) airways. Thus, it is implicated in asthma pathogenesis. Four G protein-coupled adenosine receptors (A1AR, A2aAR, A2bAR and A3AR) have been identified and characterized. However, the ADOR responsible for the effect of extADO on human airway mast cells is not clear, though indirect evidence suggests A2bAR is involved. Two types of human mast cells, MCTC and MCT, have been described. MCTC cells from skin express tryptase, chymase, carboxypeptidase A3 and cathepsin G; whereas MCT cells express tryptase alone and are the predominant type in lung. Our preliminary data reveal that high extADO (10-4 M) inhibits FceRI-mediated degranulation of MCTC (skin) mast cells, whereas low extADO (10-7 M) augments mediator release from the MCT (lung) mast cells. Thus, indicating that extADO differentially regulates mediator release from these distinct types of human mast cells. extADO also augments secretion of IL-13, a Th2 cytokine implicated in asthma pathogenesis, but inhibits production of PGD2, TNF a, GM CSF and IL 6 from MCTC cells and inhibits NF-KB activation. The proposed research will characterize the effect of extADO on mediator release from the MCTC and MCT types of mast cells activated through FceRI and also FcyRlla, an activating IgG receptor recently discovered in this lab to be constitutively expressed on skin MCTC and, possibly, on lung MCT cells, and identify the ADOR(s) responsible for the observed contrasting effects on these two types of human mast cells. Syk kinase and src tyrosine kinases Fyn and Lyn, key regulators of FceRI-dependent degranulation, will be analyzed as targets of ADOR signals in MCTC and MCT mast cells. Repression of NF-KB activation will also be assessed as a general mechanism for IL-13 production. Allergies and asthma are major health concerns in the United States. Understanding the cellular components of these disorders and the molecular mechanisms that regulate these cell types is of prime interest in our efforts to alleviate the personal and societal burdens due to these disorders. (End of Abstract)