Woszczek Grzegorz, Pawliczak Rafal, Qi Hai-Yan, Nagineni Sahrudaya, Alsaaty Sura, Logun Carolea, Shelhamer James H
Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA.
J Immunol. 2005 Oct 15;175(8):5152-9. doi: 10.4049/jimmunol.175.8.5152.
The 5-lipoxygenase pathway has been strongly implicated in the pathogenesis of chronic inflammatory disorders, such as bronchial asthma and atherosclerosis. Cysteinyl leukotrienes (cysLTs), 5-lipoxygenase pathway products, are recognized now not only as important factors in asthmatic inflammation, but also as mediators of cell trafficking and innate immune responses. To study a role of cysLTs in inflammatory reactions we have characterized the gene structure of human cysteinyl leukotriene receptor type I (cysLT(1)R). The cysLT(1)R gene consists of 5 exons that are variably spliced and a single promoter region with multiple transcription start sites. Four different cysLT(1)R transcripts were identified. RT-PCR showed dominant and wide expression of the transcript I, containing exons 1, 4, and 5, with the strongest presence in blood leukocytes, spleen, thymus, lung, and heart. The expression of cysLT(1)R is functionally regulated at the transcriptional level by IL-4 through a STAT6 response element localized to the proximal cysLT(1)R promoter region. IL-4 stimulation increased cysLT(1)R mRNA (real-time PCR) and surface protein expression (flow cytometry) in a time-dependent fashion. CysLTs (LTD(4) and LTC(4)) induced an increased production of a potent monocyte chemoattractant CCL2 (MCP-1) in IL-4-primed THP-1 cells in a dose-dependent manner. This effect was effectively inhibited by the cysLT(1)R-selective antagonist MK571 in a dose-dependent manner and only partially by a nonselective cysLT(1)R/cysLT(2)R inhibitor BAY-u9773, implying a cysLT(1)R-mediated mechanism. Thus, cysLTs signaling through cysLT(1)R might contribute to inflammatory reactions by cooperating with IL-4 in enhanced CCL2 production in human monocytic cells.
5-脂氧合酶途径与慢性炎症性疾病（如支气管哮喘和动脉粥样硬化）的发病机制密切相关。半胱氨酰白三烯（cysLTs）是5-脂氧合酶途径的产物，现在不仅被认为是哮喘炎症中的重要因素，而且是细胞转运和固有免疫反应的介质。为了研究cysLTs在炎症反应中的作用，我们对人I型半胱氨酰白三烯受体（cysLT(1)R）的基因结构进行了表征。cysLT(1)R基因由5个可变剪接的外显子和一个具有多个转录起始位点的单一启动子区域组成。鉴定出四种不同的cysLT(1)R转录本。逆转录聚合酶链反应（RT-PCR）显示转录本I（包含外显子1、4和5）占主导且广泛表达，在血白细胞、脾脏、胸腺、肺和心脏中表达最强。cysLT(1)R的表达在转录水平上通过IL-4通过位于cysLT(1)R启动子近端区域的信号转导和转录激活因子6（STAT6）反应元件进行功能调节。IL-4刺激以时间依赖性方式增加cysLT(1)R信使核糖核酸（mRNA）（实时PCR）和表面蛋白表达（流式细胞术）。半胱氨酰白三烯（LTD(4)和LTC(4)）在IL-4预处理的THP-1细胞中以剂量依赖性方式诱导强效单核细胞趋化因子CCL2（单核细胞趋化蛋白-1，MCP-1）产生增加。这种效应被cysLT(1)R选择性拮抗剂MK571以剂量依赖性方式有效抑制，并仅被非选择性cysLT(1)R/cysLT(2)R抑制剂BAY-u9773部分抑制，这意味着存在cysLT(1)R介导的机制。因此，通过cysLT(1)R的半胱氨酰白三烯信号传导可能通过在人单核细胞中与IL-4协同增强CCL2产生而有助于炎症反应。
