Exosomes from human macrophages and dendritic cells contain enzymes for leukotriene biosynthesis and promote granulocyte migration
Exosomes from human macrophages and dendritic cells contain enzymes for leukotriene biosynthesis and promote granulocyte migration
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DOI：
10.1016/j.jaci.2010.06.039
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发表时间：
2010-11-01
影响因子：
14.2
通讯作者：
Radmark, Olof
中科院分区：
文献类型：
--
作者：
Esser, Julia;Gehrmann, Ulf;Radmark, Olof
背景：白三烯(LTS)是一种强有力的促炎脂质介质，在哮喘和炎症的发病机制中起着关键作用。近年来，巨噬细胞和树突状细胞(DC)释放的纳米小泡(Exosome)越来越被认为是免疫中的信使。目的：研究人巨噬细胞、DC和血浆中的Exosome是否含有LT生物合成的酶，并研究Exosome在跨细胞LT代谢和粒细胞趋化中的潜在作用。方法：通过Western印迹、免疫电子显微镜和酶活性测定分析Exosome中LT途径酶的存在和LT的生物合成。用流式细胞仪检测巨噬细胞表面标志物的表达，并在多孔趋化系统中检测粒细胞的迁移。结果：巨噬细胞和DC的外体含有合成LT的功能酶。在完整细胞与LT生物合成中间体LTA(4)孵育后，LTB(4)是巨噬细胞的主要产物，而DC主要形成LTC(4)。然而，在两种细胞类型的外体中，LTC(4)是主要的LTA(4)代谢物。胞外体LTC(4)的形成(每毫克蛋白)超过细胞。在巨噬细胞和树突状细胞中，转化生长因子-β1上调LTA(4)水解酶，同时在外切体中也增加LTB(4)的形成。此外，转化生长因子-β1还改变了细胞和外切体表面标记蛋白的表达，减少了巨噬细胞的外切体产量。在Ca(2+)离子载体和花生四烯酸刺激下，胞外体产生趋化性二十烷酸并诱导粒细胞迁移。有趣的是，人血浆外切体中也存在活性的LTA(4)水解酶和LTC(4)合酶。结论：外切体可能通过参与LT的生物合成和粒细胞募集而参与炎症反应。(《过敏与免疫杂志》2010；126：1032-40。)
Background: Leukotrienes (LTs) are potent proinflammatory lipid mediators with key roles in the pathogenesis of asthma and inflammation. Recently, nanovesicles (exosomes), released from macrophages and dendritic cells (DCs), have become increasingly appreciated as messengers in immunity.Objective: We investigated whether exosomes from human macrophages, DCs, and plasma contain enzymes for LT biosynthesis and studied potential roles for exosomes in transcellular LT metabolism and granulocyte chemotaxis.Methods: The presence of LT pathway enzymes and LT biosynthesis in exosomes and cells was analyzed by Western blot, immunoelectron microscopy, and enzyme activity assays. Surface marker expression was evaluated by flow cytometry, and granulocyte migration was assessed in a multiwell chemotaxis system.Results: Exosomes from macrophages and DCs contain functional enzymes for LT biosynthesis. After incubation of intact cells with the LT biosynthesis intermediate LTA(4), LTB(4) was the major product of macrophages, whereas DCs primarily formed LTC(4). However, in exosomes from both cell types, LTC(4) was the predominant LTA(4) metabolite. Exosomal LTC(4) formation (per milligram protein) exceeded that of cells. In macrophages and DCs, TGF-beta 1 upregulated LTA(4) hydrolase along with increased LTB(4) formation also in the exosomes. Moreover, TGF-beta 1 modified the expression of surface marker proteins on cells and exosomes and reduced the exosome yield from macrophages. On Ca(2+)-ionophore and arachidonic acid stimulation, exosomes produced chemotactic eicosanoids and induced granulocyte migration. Interestingly, active LTA(4) hydrolase and LTC(4) synthase were present also in exosomes from human plasma.Conclusion: Our findings indicate that exosomes can contribute to inflammation by participation in LT biosynthesis and granulocyte recruitment. (J Allergy Clin Immunol 2010;126:1032-40.)