LIPID METABOLIC ALTERATIONS DURING MAST CELL SECRETION

肥大细胞炎性介质的形成和释放起中心作用 在即刻超敏反应中的作用。此外，肥大细胞 衍生的介体似乎在进化中扮演重要的角色。 补体诱导的某些炎症机制及其调节作用 对特定淋巴细胞亚群的影响。最近的研究表明， 脂肪代谢的改变可能在肥大细胞中起核心作用 释放调解人。除了下面描述的脂类甲基化事件 其他的，这个实验室已经证明了32PO4标记的精选 磷脂与脂质中间体的积累 SN-1，2-二酰甘油(双甘油酯或DG)动力学平行介体 释放，具有几乎相同的药理抑制和剂量 响应关系。这项工作的长期目标是理解 脂代谢途径在特定亚细胞中的作用 引起和/或调节肥大细胞介体释放的隔室。DG 新陈代谢将是核心利益所在。一种新开发的利用 肥大细胞“胞质”(由被包围的完整细胞组成的小体 由完整的质膜和含有几乎没有颗粒的细胞质组成 和其他细胞器)将被用来表征脂代谢 与质膜有关的反应。以后的研究将探索 细胞质颗粒膜中的脂类代谢反应。具体目标 这一建议包括：1)物理和生化特性 肥大细胞胞质参数；2)脂肪酸测定 肥大细胞分泌过程中积累的DG的组成；3) 研究DG的原位生成或外源添加DG的方式 类似物影响介质释放；4)确定代谢来源和 刺激肥大细胞产生DG的机制；5)研究 消除DG的途径及其潜在的负面重要性 调节分泌。 这些对生物化学的性质和亚细胞位置的研究 导致释放调解人的机制应该有助于更清楚地 肥大细胞免疫激活的观点。这样的知识应该 促进开发新的药理策略以抑制 过敏障碍或增加肥大细胞对 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.