血小板是血管止血的关键作用者，在活化信号的引导下迅速招募、聚集和形成凝血块。止血的经典过程已经被很好地描述并且与病理性血栓形成具有许多相似之处。然而，在稳态和炎症条件下，血小板还在确保血管稳态和防止微出血方面发挥至关重要的作用。在这些情况下，血小板使用不同的受体、信号通路和随后的执行功能来完成它们的任务：它们主要以个体哨兵的形式快速适应局部微环境，而不仅仅是形成血栓。在本综述中，我们总结了先前认识到的以及更近期的研究，阐明了无核、小型血小板如何在感染、无菌炎症甚至恶性肿瘤的挑战下保持血管完整性。我们剖析了血小板如何被招募到血管壁，如何识别损伤部位，以及如何以单个细胞形式防止出血。此外，我们还讨论了血小板与白细胞和内皮细胞相互作用的机制和后果，粘附以及信号受体的相关性，特别是ITAM受体，以及与凝血系统的相互作用。最后，我们概述了对炎症性止血和血管完整性的最新认识如何在防止危重病患者出血事件和血管功能障碍的新治疗策略开发方面发挥作用。© 2023年美国血液学会版权所有。

Platelets are key vascular effectors in hemostasis, with activation signals leading to fast recruitment, aggregation, and clot formation. The canonical process of hemostasis is well characterized and shares many similarities with pathological thrombus formation. However, platelets are also crucially involved in the maintenance of vascular integrity under both steady state and inflammatory conditions by ensuring blood vessel homeostasis and preventing microbleeds. In these settings, platelets use distinct receptors, signaling pathways and ensuing effector functions to carry out their deeds: Instead of simply forming clots, they mainly act as individual sentinels that swiftly adapt their behavior to the local microenvironment. In this Review, we summarize previously recognized and more recent studies that have elucidated how anucleate, small platelets manage to maintain vascular integrity when faced with challenges of infection, sterile inflammation and even malignancy. We dissect how platelets are recruited to the vascular wall, how they identify sites of injury, and how they prevent hemorrhage as single cells. Further, we discuss mechanisms and consequences of platelets interacting with leukocytes and endothelial cells, the relevance of adhesion as well as signaling receptors, in particular ITAM receptors, and crosstalk with the coagulation system. Finally, we outline how recent insights into inflammatory hemostasis and vascular integrity may aid in the development of novel therapeutic strategies to prevent hemorrhagic events and vascular dysfunction in critically ill patients.Copyright © 2023 American Society of Hematology.