LIPID METABOLIC ALTERATIONS DURING MAST CELL SECRETION

肥大细胞形成和释放炎性介质起着重要作用 在速发型超敏反应中的作用。 此外，肥大细胞 衍生介质似乎在进化中发挥重要作用， 某些补体诱导的炎症机制，并发挥调节 对特定淋巴细胞亚类的影响。 最近的研究表明， 脂质代谢的改变可能在肥大细胞 释放介质。 除了脂质甲基化事件， 其他人，这个实验室已经表明，32 PO 4标记的选择， 磷脂和脂质中间体的积累 sn-1，2-二酰基甘油（甘油二酯或DG）动力学平行介质 释放并具有几乎相同的药理学抑制和剂量 反应关系。 这项工作的长期目标是了解 脂质代谢途径在特定的亚细胞内 在引起和/或调节肥大细胞介质释放的区室中。 DG 代谢将是中心的兴趣。 一个新开发的系统， 肥大细胞“细胞质”（由完整细胞形成的体， 由完整的质膜和含有细胞质几乎没有颗粒 和其他细胞器）将用于表征脂质代谢 与质膜有关的反应。 以后的研究将探索 细胞质颗粒膜的脂质代谢反应。 具体目标 该建议包括：1）表征物理和生物化学 肥大细胞胞质参数; 2）测定脂肪酸 在肥大细胞分泌期间积累的DG的组成; 3） 研究原位生成DG或外源添加DG 类似物影响介质释放; 4）确定代谢来源， 肥大细胞在刺激下产生DG的机制; 5）研究 清除DG的途径及其在负面影响中的潜在重要性 调节分泌。 这些研究的性质和亚细胞网站的生化 导致释放调解人的机制应有助于更清楚地 从肥大细胞的免疫激活的角度来看。 这样的知识应该 促进新的药理学策略的发展， 过敏性疾病或增加肥大细胞对 保护性免疫或感染的解决。

Formation and release of inflammatory mediators by mast cells play central roles in immediate hypersensitivity reactions. In addition, mast cell derived mediators appear to play significant roles in the evolution of certain complement-induced inflammatory mechanisms and exert regulatory influences on particular lymphocyte subclasses. Recent work has shown that alterations in lipid metabolism likely play a central role in mast cell mediator release. In addition to lipid methylation events described by others, this laboratory has shown that 32PO4 labeling of selected phospholipids and accumulation of the lipid intermediate sn-1,2-diacylglycerol (diglyceride or DG) kinetically parallel mediator release and have nearly identical pharmacologic inhibition and dose response relationships. The long range goal of this work is to understand what roles lipid metabolic pathways play in specific subcellular compartments in causing and/or regulating mast cell mediator release. DG metabolism will be of central interest. A newly developed system utilizing mast cell "cytoplasts" (bodies formed from intact cells that are surrounded by intact plasma membrane and contain cytoplasm nearly devoid of granules and other organelles) will be employed to characterize lipid metabolic reactions associated with the plasma membrane. Later studies will explore lipid metabolic reactions in cytoplasmic granule membranes. Specific aims of this proposal include: 1) characterizing physical and biochemical parameters of mast cell cytoplasts; 2) determining the fatty acid composition of the DG that accumulates during mast cell secretion; 3) investigating how in situ generation of DG or exogenous addition of a DG analogue affects mediator release; 4) determining the metabolic origin and mechanism of production of DG in stimulated mast cells; 5) investigating the pathways that remove DG and their potential importance in negative modulation of secretion. These studies of the nature and subcellular sites of the biochemical mechanisms leading to mediator release should contribute to a much clearer view of immunologic activation of mast cells. Such knowledge should facilitate the development of new pharmacologic strategies to suppress allergic disorders or to augment the contribution of mast cells to protective immunity or the resolution of infections.