Stimulation of Toll-like receptor 2 in human platelets induces a thromboinflammatory response through activation of phosphoinositide 3-kinase.
Stimulation of Toll-like receptor 2 in human platelets induces a thromboinflammatory response through activation of phosphoinositide 3-kinase.
复制标题
DOI：
10.1161/circresaha.108.185785
复制
发表时间：
2009-02-13
影响因子：
20.1
通讯作者：
Freedman JE
中科院分区：
文献类型：
--
作者：
Blair P;Rex S;Vitseva O;Beaulieu L;Tanriverdi K;Chakrabarti S;Hayashi C;Genco CA;Iafrati M;Freedman JE
先天免疫系统的细胞使用Toll样受体（TLR）来启动对微生物感染的促炎反应。最近的研究表明，急性感染与血管血栓事件风险的短暂增加有关。虽然血小板在急性血栓形成中起着核心作用，并且越来越多的证据表明它们在炎症和先天免疫中的作用，但对血小板TLR的表达和功能的研究有限。在本研究中，我们证明，人类血小板表达TLR 2，TLR 1和TLR 6。用合成的TLR 2/TLR 1激动剂Pam 3CSK 4孵育分离的血小板，直接诱导血小板聚集和粘附于胶原。这些功能反应在TLR 2缺陷小鼠和人血小板中被TLR 2阻断抗体预处理抑制。血小板TLR 2的刺激还增加了P-选择素表面表达、整合素αIIbβ3的活化、活性氧的产生以及人全血中血小板-中性粒细胞异型聚集体的形成。TLR 2刺激还激活血小板中的磷酸肌醇3-激酶（PI 3-K）/Akt信号通路，并且PI 3-K的抑制显著降低Pam 3CSK 4诱导的血小板应答。用活的牙龈卟啉单胞菌（Porphyromonas gingivalis）（一种革兰氏阴性致病菌，其使用TLR 2用于先天免疫信号传导）进行的体内攻击也在野生型但非TLR 2缺陷小鼠中诱导血小板-中性粒细胞聚集体的显著形成。总之，这些数据提供了人类血小板表达能够识别细菌组分并激活血小板血栓形成和/或炎症途径的功能性TLR 2的第一个证明。这项工作证实了血小板在免疫和炎症反应中的作用，并提出了细菌直接激活血小板的机制。
Cells of the innate immune system use Toll-like receptors (TLRs) to initiate the proinflammatory response to microbial infection. Recent studies have shown acute infections are associated with a transient increase in the risk of vascular thrombotic events. Although platelets play a central role in acute thrombosis and accumulating evidence demonstrates their role in inflammation and innate immunity, investigations into the expression and functionality of platelet TLRs have been limited. In the present study, we demonstrate that human platelets express TLR2, TLR1, and TLR6. Incubation of isolated platelets with Pam3CSK4, a synthetic TLR2/TLR1 agonist, directly induced platelet aggregation and adhesion to collagen. These functional responses were inhibited in TLR2-deficient mice and, in human platelets, by pretreatment with TLR2-blocking antibody. Stimulation of platelet TLR2 also increased P-selectin surface expression, activation of integrin αIIbβ3, generation of reactive oxygen species, and, in human whole blood, formation of platelet–neutrophil heterotypic aggregates. TLR2 stimulation also activated the phosphoinositide 3-kinase (PI3-K)/Akt signaling pathway in platelets, and inhibition of PI3-K significantly reduced Pam3CSK4-induced platelet responses. In vivo challenge with live Porphyromonas gingivalis, a Gram-negative pathogenic bacterium that uses TLR2 for innate immune signaling, also induced significant formation of platelet–neutrophil aggregates in wild-type but not TLR2-deficient mice. Together, these data provide the first demonstration that human platelets express functional TLR2 capable of recognizing bacterial components and activating the platelet thrombotic and/or inflammatory pathways. This work substantiates the role of platelets in the immune and inflammatory response and suggests a mechanism by which bacteria could directly activate platelets.