血小板在 NET 网络中交织炎症与血栓。

Platelets in the NETworks interweaving inflammation and thrombosis.

机构信息

Department of Anesthesiology, Intensive Care and Pain Medicine, University Hospital Münster, Münster, Germany.

Department of Dermatology, University Hospital Münster, Münster, Germany.

出版信息

Front Immunol. 2022 Aug 1;13:953129. doi: 10.3389/fimmu.2022.953129. eCollection 2022.

Abstract

Platelets are well characterized for their indispensable role in primary hemostasis to control hemorrhage. Research over the past years has provided a substantial body of evidence demonstrating that platelets also participate in host innate immunity. The surface expression of pattern recognition receptors, such as TLR2 and TLR4, provides platelets with the ability to sense bacterial products in their environment. Platelet α-granules contain microbicidal proteins, chemokines and growth factors, which upon release may directly engage pathogens and/or contribute to inflammatory signaling. Additionally, platelet interactions with neutrophils enhance neutrophil activation and are often crucial to induce a sufficient immune response. In particular, platelets can activate neutrophils to form neutrophil extracellular traps (NETs). This specific neutrophil effector function is characterized by neutrophils expelling chromatin fibres decorated with histones and antimicrobial proteins into the extracellular space where they serve to trap and kill pathogens. Until now, the mechanisms and signaling pathways between platelets and neutrophils inducing NET formation are still not fully characterized. NETs were also detected in thrombotic lesions in several disease backgrounds, pointing towards a role as an interface between neutrophils, platelets and thrombosis, also known as immunothrombosis. The negatively charged DNA within NETs provides a procoagulant surface, and in particular NET-derived proteins may directly activate platelets. In light of the current COVID-19 pandemic, the topic of immunothrombosis has become more relevant than ever, as a majority of COVID-19 patients display thrombi in the lung capillaries and other vascular beds. Furthermore, NETs can be found in the lung and other tissues and are associated with an increased mortality. Here, virus infiltration may lead to a cytokine storm that potently activates neutrophils and leads to massive neutrophil infiltration into the lung and NET formation. The resulting NETs presumably activate platelets and coagulation factors, further contributing to the subsequent emergence of microthrombi in pulmonary capillaries. In this review, we will discuss the interplay between platelets and NETs and the potential of this alliance to influence the course of inflammatory diseases. A better understanding of the underlying molecular mechanisms and the identification of treatment targets is of utmost importance to increase patients' survival and improve the clinical outcome.

摘要

血小板在控制出血的初级止血中具有不可或缺的作用,这一点已经得到了很好的描述。过去几年的研究提供了大量证据,证明血小板也参与宿主固有免疫。模式识别受体(如 TLR2 和 TLR4)在血小板表面的表达使血小板能够感知其环境中的细菌产物。血小板α-颗粒含有杀菌蛋白、趋化因子和生长因子,这些物质释放后可以直接与病原体结合,并/或有助于炎症信号转导。此外,血小板与中性粒细胞的相互作用增强了中性粒细胞的激活,这对于诱导充分的免疫反应通常是至关重要的。特别是,血小板可以激活中性粒细胞形成中性粒细胞胞外诱捕网(NETs)。这种特定的中性粒细胞效应功能的特点是,中性粒细胞将带有组蛋白和抗菌蛋白的染色质纤维逐出细胞外空间,在那里它们可以捕获和杀死病原体。到目前为止,血小板和中性粒细胞之间诱导 NET 形成的机制和信号通路仍未完全阐明。在几种疾病背景下的血栓病变中也检测到了 NETs,这表明它们作为中性粒细胞、血小板和血栓形成(也称为免疫血栓形成)之间的接口发挥作用。NETs 中的带负电荷的 DNA 提供了一个促凝表面,特别是 NET 衍生的蛋白质可能直接激活血小板。鉴于当前的 COVID-19 大流行,免疫血栓形成的话题比以往任何时候都更加相关,因为大多数 COVID-19 患者的肺部毛细血管和其他血管床都有血栓形成。此外,NETs 可以在肺部和其他组织中找到,并与死亡率增加有关。在这里,病毒渗透可能导致细胞因子风暴,强烈激活中性粒细胞,并导致大量中性粒细胞浸润肺部和 NET 形成。由此产生的 NETs 可能会激活血小板和凝血因子,进一步导致肺部毛细血管微血栓的后续出现。在这篇综述中,我们将讨论血小板与 NETs 之间的相互作用以及这种联合对炎症性疾病进程的潜在影响。更好地理解潜在的分子机制,并确定治疗靶点,对于提高患者的生存率和改善临床结果至关重要。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/d463/9376363/b3b6c589947b/fimmu-13-953129-g001.jpg

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