PHARMACOLOGY OF LIPOXYGENASE INHIBITORS

花生四烯酸(AA)是多种炎症介质的前体。 和过敏反应。5-脂氧合酶途径的AA代谢物 包括白三烯LTB4，它是一种非常有效化学趋向剂和 气道肌收缩剂，以及LTC4、LTD4和LTE4，它们是活性的 过敏性反应和即刻反应的重要介体--SRS组分 超敏反应。白三烯是在白细胞中产生的， 淋巴细胞、巨噬细胞、RBL-1以及某些肥大和肥大细胞瘤细胞。 15-脂氧合酶产物15-HETE抑制中性粒细胞中的5-脂氧合酶 淋巴细胞导致白三烯和5-羟色胺的形成减少。 我们发现15-HETE可以激活细胞内隐藏的5-脂氧合酶。 培养的肥大/嗜碱粒细胞系PT-18形成LTB4和5-HETE 外源添加AA。15-HETE诱导的5-脂氧合酶的激活 吲哚美辛可使PT-18细胞的增殖倍数增加4倍。 在RBL-1细胞中，观察到15-HETE类似地诱导LT的形成 用1MU的A23187进行预处理。然而，随着这一数量的增加 发现15-HETE对LT生物合成有抑制作用。最后， 15-HETE还可促进大鼠腹膜SRS/LT的体内形成 用A23187刺激。 本课题旨在研究LT的调制机制 15-HETE的生物合成。体外研究将使用PT-18和RBL-1 细胞。我们将确定15-HETE的进一步代谢物或 结构上与15-HETE相关的类似物是生理激活剂。我们 还将检查15-HETE是否直接作用于5-脂氧合酶，通过 A受体和/或通过诱导钙离子通量。我们会尝试找出 环氧合酶代谢物，它能抑制细胞的总活性 15-HETE对PT-18细胞5-脂氧合酶活性的影响。探讨其发病机制。 15-HETE对大鼠腹膜SRS/LT形成的体内调节 将检测15-HETE对体外培养的腹膜的影响 巨噬细胞、肥大细胞和中性粒细胞决定15-HETE如何调节 不同免疫学和非免疫学诱导的活体SRS形成 刺激并研究阿司匹林或消炎痛的预处理 影响15-HETE对SRS产生的体内调节。 从这些研究中获得的信息将提供新的见解 5-脂氧合酶的调节，5-脂氧合酶是机体的重要组成部分。 白三烯的形成。希望这最终将导致 治疗某些炎症性疾病的新方法 疾病。

Arachidonic acid (AA) is the precursor of various mediators of inflammatory and allergic reactions. AA metabolites of the 5-lipoxygenase pathway include leukotriene LTB4 which is a very potent chemotactic agent and airway muscle contractant, and LTC4, LTD4 and LTE4, which are the active components of SRS, an important mediator in anaphylaxis and immediate hypersensitivity reactions. Leukotrienes are produced in leukocytes, lymphocytes, macrophages, RBL-1 and certain mast and mastocytoma cells. The 15-lipoxygenase product 15-HETE inhibits the 5-lipoxygenase in PMNs and lymphocytes resulting in decreased formation of leukotrienes and 5-HETE. We have found that 15-HETE can activate a cryptic 5-lipoxygenase in the cultured mast/basophil cell line PT-18 forming LTB4 and 5-HETE from exogenously added AA. 15-HETE-induced activation of the 5-lipoxygenase was enhanced four-fold upon pretreatment of PT-18 cells with indomethacin. Similar induction of LT formation by 15-HETE was observed in RBL-1 cells pretreated with 1 MuM A23187. However, with higher amounts of this ionophore, inhibition of LT biosynthesis by 15-HETE was found. Finally, 15-HETE also potentiated SRS/LT formation in vivo in the rat peritoneum stimulated with A23187. This project is designed to investigate the mechanism of modulation of LT biosynthesis by 15-HETE. The in vitro studies will use PT-18 amd RBL-1 cells. We will determine whether a further metabolite of 15-HETE or a structurally related analog of 15-HETE is the physiological activator. We will also examine whether 15-HETE acts directly on the 5-lipoxygenase, via a receptor and/or via induction of Ca++ flux. We will attempt to identify the cyclooxygenase metabolite that inhibits the total activation of the 5-lipoxygenase in PT-18 cells by 15-HETE. To investigate the mechanism of in vivo regulation of SRS/LT formation in the rat peritoneum by 15-HETE, we will examine the in vitro effects of 15-HETE on isolated peritoneal macrophages, mast cells and neutrophils, determine how 15-HETE modulates in vivo SRS formation induced by different immunological and non-immunological stimuli and investigate how pretreatment with aspirin or indomethacin affects the in vivo regulation of SRS production by 15-HETE. The information obtained from these studies will provide new insights into regulation of the 5-lipoxygenase which is an essential component in the formation of leukotrienes. It is hoped that ultimately this will lead to new therapeutic approaches in the management of certain inflammatory diseases.