Understanding the role of platelets in stroke through comprehensive immunological assessment in relevant clinical cohorts and preclinical models

在英国，中风每年影响大约10万人，仍然是成人残疾的主要原因。大多数卒中与动脉闭塞(缺血性卒中：85%)有关，而其余卒中与脑出血或蛛网膜下腔出血(出血性卒中：15%)有关。不幸的是，缺血性或出血性中风的治疗选择有限，这对研究和临床实践构成了巨大的未得到满足的需求。人们普遍认为，在中风的风险、损伤的演变和组织损伤的修复方面，调节失调的炎症和血栓形成与中风疾病的病理生理学密切相关。此外，先天细胞免疫反应的短暂抑制增加了卒中后感染的易感性，这是常见的，并对预后产生不利影响。因此，血栓-炎症-免疫通路在决定卒中预后方面起着关键作用，并为治疗干预提供了机会。血小板是髓系血细胞，在血液中循环，寿命为7-10天。尽管它们没有细胞核，但它们越来越被认为是复杂的细胞，含有3种不同类型的颗粒(a颗粒、致密颗粒和溶酶体)和残留的RNA。尽管血小板作为血栓形成止血的主要介体的作用由来已久，但它们也越来越多地成为天然免疫反应的关键介体。血小板通过特定的表面受体与白细胞(如单核细胞、中性粒细胞和树突状细胞)直接相互作用，形成血小板-白细胞复合体，影响先天免疫反应和获得性免疫反应。此外，血小板还可以结合中风相关感染中常见的细菌，并释放抗菌产品，这可能会补充其他固有的细胞防御机制。尽管越来越多的人认识到血小板在免疫反应中的作用，但中风中血小板-免疫细胞相互作用的确切功能和临床相关性还缺乏特征或了解。我们最近建立了全面的外周血液天然(单核细胞、中性粒细胞)和适应性(淋巴细胞)细胞成分的免疫表型和功能状态图谱，并成功地应用于实验性中风啮齿动物和中风患者的血液样本。该项目的总体目标是开发补充方法学来评估脑血管疾病中的血小板。目的是建立从全血样本中分离血小板和评估免疫表型、白细胞结合和功能状态的可重复性的方案。这些方法将应用于实验性中风啮齿动物模型、健康人对照组以及急性缺血性和出血性中风患者的血液样本。

Stroke affects approximately 100, 000 people each year in the UK, and remains the leading cause of adult disability. The majority of strokes are associated with arterial occlusion (ischaemic stroke: 85%), whilst the remainder are due to haemorrhage into the brain or subarachnoid spaces (haemorrhagic stroke: 15%). Unfortunately, treatment options for ischaemic or haemorrhagic stroke are limited posing a major unmet need for research and clinical practice.It is widely recognised that dysregulated inflammation and thrombosis are strongly implicated in the pathophysiology of stroke disease, both in terms of risk of stroke, and evolution of injury and repair of tissue injury. Further, transient suppression of innate cellular immune responses increases susceptibility to infections after stroke, which occur commonly and adversely impact upon outcomes. Thrombo-inflammatory-immune pathways therefore play a critical part in determining outcomes from stroke and provide opportunities for therapeutic intervention. Platelets are myeloid-derived blood cells which circulate in the blood with a lifespan of 7-10 days. Although they lack a nucleus, they are increasingly recognised as complex cells and contain 3 discreet types of granules (a-granules, dense granules and lysosomes) and residual RNA. Whilst the role of platelets as the primary mediators of thrombosis-haemostasis is long established, they are also increasingly emerging as key mediators of innate immune responses. Platelets directly interact with leucocytes (e.g. monocytes, neutrophils and dendritic cells) via specific surface receptors, forming platelet-leucocyte complexes which influence both innate and adaptive immune responses. Further, platelets can also bind bacteria commonly implicated in stroke-associated infections, and release antimicrobial products which may supplement other innate cellular defence mechanisms. Despite the increasing recognition of platelets in immune responses, the precise functional and clinical relevance of platelet-immune cellular interactions in stroke are poorly characterised or understood. We have recently established comprehensive protocols for mapping immunophenotype and functional status of peripheral blood innate (monocyte, neutrophil) and adaptive (lymphocyte) cellular components and applied these successfully to blood samples from rodents with experimental stroke and patients with stroke. The overall aim of this project is to develop complementary methodologies to evaluate platelets in cerebrovascular disease. The objectives are to establish reproducible protocols for isolating platelets from whole blood samples and for evaluating immunophenotype, leucocyte-binding and functional status. These methods will be applied to blood samples from rodent models of experimental stroke, healthy human controls and patients with acute ischaemic and haemorrhagic stroke.