Prevention of Neutrophil Extravasation by α2-Adrenoceptor-Mediated Endothelial Stabilization
Prevention of Neutrophil Extravasation by α2-Adrenoceptor-Mediated Endothelial Stabilization
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DOI：
10.4049/jimmunol.1400255
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发表时间：
2014-09-01
影响因子：
4.4
通讯作者：
Diaz-Gonzalez, Federico
中科院分区：
文献类型：
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作者：
Maria Herrera-Garcia, Ada;Jesus Dominguez-Luis, Maria;Diaz-Gonzalez, Federico
肾上腺素能受体在炎症介导细胞表面表达，但它们在调节炎症反应中的潜在作用仍知之甚少。这项工作的目的是研究α2-肾上腺素能激动剂对体内炎症反应的影响并确定其作用机制。在两种小鼠炎症模型（酵母聚糖气囊和巯基乙酸诱导的腹膜炎模型）中，i.m.使用甲苯噻嗪或 UK14304（两种 α2-肾上腺素能激动剂）治疗，可使中性粒细胞迁移减少 60%。 α2-肾上腺素能拮抗剂 RX821002 消除了这种作用。在流式细胞术实验中，经 α2 激动剂处理后，小鼠和人类中性粒细胞中 L-选择素和 CD11b 的基底表面表达均未发生改变。 HUVEC 中的类似实验表明，UK14304 阻止了 ICAM-1 的激活依赖性上调。相比之下，UK14304 增加了电阻并减少了通过汇合的 HUVEC 单层的大分子运输。在流动室实验中，在毛细血管后微静脉样流动条件下，用α2-激动剂预处理HUVEC，但不影响中性粒细胞，减少了跨内皮迁移，而不影响中性粒细胞滚动。有趣的是，通过免疫荧光、共聚焦分析和蛋白质印迹分析，α2-激动剂分别阻止了 TNF-α 介导的粘附连接分子、VE-钙粘蛋白、β-连环蛋白和斑球蛋白表达的减少，并减少了 ICAM-1 介导的 VE-钙粘蛋白的磷酸化。这些发现表明，α2-肾上腺素受体触发信号，在炎症反应期间保护内皮粘附连接的完整性，从而将血管内皮作为人类炎症过程管理的治疗靶点。
Adrenergic receptors are expressed on the surface of inflammation-mediating cells, but their potential role in the regulation of the inflammatory response is still poorly understood. The objectives of this work were to study the effects of alpha 2-adrenergic agonists on the inflammatory response in vivo and to determine their mechanism of action. In two mouse models of inflammation, zymosan air pouch and thioglycolate-induced peritonitis models, the i.m. treatment with xylazine or UK14304, two alpha 2-adrenergic agonists, reduced neutrophil migration by 60%. The alpha 2-adrenergic antagonist RX821002 abrogated this effect. In flow cytometry experiments, the basal surface expression of L-selectin and CD11b was modified neither in murine nor in human neutrophils upon alpha 2-agonist treatment. Similar experiments in HUVEC showed that UK14304 prevented the activation-dependent upregulation of ICAM-1. In contrast, UK14304 augmented electrical resistance and reduced macromolecular transport through a confluent HUVEC monolayer. In flow chamber experiments, under postcapillary venule-like flow conditions, the pretreatment of HUVECs, but not neutrophils, with alpha 2-agonists decreased transendothelial migration, without affecting neutrophil rolling. Interestingly, alpha 2-agonists prevented the TNF-alpha-mediated decrease in expression of the adherens junctional molecules, VE-cadherin, beta-catenin, and plakoglobin, and reduced the ICAM-1-mediated phosphorylation of VE-cadherin by immunofluorescence and confocal analysis and Western blot analysis, respectively. These findings indicate that alpha 2-adrenoceptors trigger signals that protect the integrity of endothelial adherens junctions during the inflammatory response, thus pointing at the vascular endothelium as a therapeutic target for the management of inflammatory processes in humans.