中性粒细胞胞外诱捕网在血栓形成中作用的研究进展

血栓栓塞性疾病是全球性重大健康问题。多项研究表明中性粒细胞与血栓形成密切相关。活化的中性粒细胞可以响应各种刺激释放中性粒细胞胞外诱捕网,激活凝血级联、补体系统和血小板等促进血栓形成,参与动脉血栓、静脉血栓和癌症相关血栓等各种血栓性疾病。本文就中性粒细胞胞外诱捕网在血栓形成中的作用机制进行总结,以期为抗栓治疗提供新靶点和新思路。     

中性粒细胞外陷阱在血栓形成中的作用及研究进展

血栓性疾病严重危害人群健康。中性粒细胞外陷阱作为中性粒细胞的固有免疫机制之一,在帮助机体抵御病原体之外还可通过其结构的支架作用和组分的凝血激活作用促进血栓形成,并在动静脉血栓、抗凝脂综合征以及肿瘤相关血栓的动物疾病模型、人类血栓样本和体外实验中得到了证实。主要介绍中性粒细胞外陷阱的形成机制,重点介绍中性粒细胞外陷阱与血栓形成的关联,以及在血栓性疾病和新型冠状病毒肺炎中作用,旨在为血栓防治相关研究提供参考。     

中性粒细胞胞外诱捕网在寄生虫感染中的作用和机制研究进展

中性粒细胞胞外诱捕网（NET）是中性粒细胞胞内染色质与颗粒蛋白结合后释放至胞外所形成的网状结构。研究表明，原虫和蠕虫等寄生虫感染可诱导NET形成，并在抗寄生虫的免疫防御与寄生虫感染引起的免疫病理中发挥重要作用。本文综述了NET在常见原虫和蠕虫感染中的形成机制及其作用的最新研究进展，旨在为寄生虫病预防与治疗提供新思路。     

肽酰基精氨酸脱亚氨酶4和中性粒细胞胞外诱捕网形成在实验性动脉粥样硬化和动脉损伤中的作用:浅表糜烂的影响

正中性粒细胞可能促进人类动脉粥样硬化的血栓并发症的发生。特别是中性粒细胞胞外诱捕网(neutrophil extracellular traps,NETs)可加剧局部炎症,并放大和加剧动脉内膜损伤和血栓形成。肽酰基精氨酸脱亚氨酶4(peptidyl arginine deiminase 4,PAD4)参与NET的形成,但对该酶在动脉粥样硬化血栓形成中的     

中性粒细胞胞外诱捕网在炎症性肠病中的作用机制及相关靶向治疗

炎症性肠病(IBD)是一类发病机制尚不明确的慢性非特异性肠道炎性疾病。中性粒细胞胞外诱捕网(NET)是中性粒细胞受到刺激后释放产生的网状结构, 由DNA骨架、组蛋白、颗粒蛋白和胞质蛋白组成。研究发现NET可以有效捕获并杀灭病原菌, 但过量的NET会加剧炎症反应、破坏肠黏膜屏障、促使血栓形成。现就NET在IBD发病中的作用机制做一概述, 并进一步探讨NET相关靶点在临床治疗IBD中的应用前景。     

急性动脉血栓患者中性粒细胞黏附分子表达的变化及意义

目的探讨急性动脉血栓形成患者中性粒细胞(PMN)表面黏附分子CD62L和CD11b/CD18的表达及其意义。方法选择急性心、脑动脉血栓患者各20例,健康志愿者30例作为对照组。运用流式细胞仪检测外周血中PMN表面黏附分子CD62L和CD11b/CD18表达。结果相对于正常组黏,动脉血栓组黏附分子CD62L平均抗体阳性表达率显著降低(P<0.001);CD11b/CD18平均阳性表达率显著升高(P<0.001)。动脉血栓组内部CD62L、CD11b/CD18相关分析,二者呈明显负相关(r=-0.259,P<0.001)。结论在动脉血栓的急性期,以细胞黏附为表现的PMN活化加快了血栓的进程,可能是血栓形成的重要发病原因之一。     

中性粒细胞胞外陷阱在肾脏疾病中的研究进展

中性粒细胞胞外陷阱(NETs)是一种由染色质和多种颗粒蛋白组成的细胞外网状结构。形成NETs是中性粒细胞的一种新型死亡方式, 亦是一种新型作用机制。研究表明, NETs能杀灭多种病原体。然而, NETs亦通过不同的作用参与多种疾病的发生发展, 肾脏是NETs主要累及的器官之一。本文就NETs 的形成及其在多种肾脏疾病中的研究进展进行综述, 为肾脏疾病的治疗提供新思路。     

中性粒细胞胞外陷阱网在动脉粥样硬化进展中的作用

动脉粥样硬化是动脉血管壁长期渐进性的炎性病理过程。动脉粥样硬化斑块破裂及血栓形成所引起的急性心血管事件,严重威胁人类健康及生命。近年来中性粒细胞在动脉粥样硬化中的作用受到广泛关注。活化的中性粒细胞向胞外释放网状结构,即中性粒细胞胞外陷阱网。中性粒细胞胞外陷阱网在自身免疫疾病、急性肺损伤、深静脉血栓等疾病中具有致病作用。大量研究表明中性粒细胞胞外陷阱网与动脉粥样硬化及血栓形成相关,其标志物可以作为冠心病的预测因子,预测心脏主要不良事件及疾病预后。本文将就中性粒细胞胞外陷阱网在动脉粥样硬化进展中的作用进行综述。     

替格瑞洛与氯吡格雷抑制中性粒细胞减轻急性ST段抬高型心肌梗死患者冠状动脉血栓炎症的对比研究

目的比较替格瑞洛与氯吡格雷对急性ST段抬高型心肌梗死患者中性粒细胞的影响从而减轻冠状动脉血栓炎症。方法选取哈尔滨医科大学附属第一医院2016年5月—2017年3月行急诊经皮冠脉介入术的ST段抬高型心肌梗死患者,信封法随机分成替格瑞洛组(23例)和氯吡格雷组(24例),比较两组冠状动脉血栓中中性粒细胞数量、髓过氧化物酶阳性细胞数量和冠状动脉血浆DNA-组蛋白/NETs的表达。结果与氯吡格雷组相比,替格瑞洛组血栓中中性粒细胞和髓过氧化物酶阳性表达面积百分比分别减少45%[(10.11%±6.16%)vs(18.23%±7.26%),P<0.01]和43%[(13.38%±7.29%)vs(23.57%±8.33%),P<0.01]。两组术后24 h外周血中性粒细胞数量和冠状动脉血DNA-组蛋白/NETs表达均无统计学差异(P>0.05)。结论与氯吡格雷相比,替格瑞洛更显著地减少冠状动脉血栓的中性粒细胞数量和髓过氧化物酶阳性细胞数量,从而减轻冠状动脉血栓炎症。     

中性粒细胞凋亡与低氧血症

中性粒细胞是机体最主要的炎性反应细胞,其数量、功能和生命期限影响着炎性反应的发生、发展和转归。中性粒细胞主要通过凋亡被单核巨噬细胞识别、吞噬,不释放其细胞内毒性内容物,从而限制中性粒细胞介导的组织损伤、并促进炎性反应消散。如果中性粒细胞生存力延长,周围细胞或组织将会被破坏。中性粒细胞凋亡(neutrophil apoptosis,NA)由胞内死亡/存活信号路径的复杂网络介导并受一系列的细胞外刺激如     

Myeloperoxidase is required for neutrophil extracellular trap formation: implications for innate immunity

The granule enzyme myeloperoxidase (MPO) plays an important role in neutrophil antimicrobial responses. However, the severity of immunodeficiency in patients carrying mutations in MPO is variable. Serious microbial infections, especially with Candida species, have been observed in a subset of completely MPO-deficient patients. Here we show that neutrophils from donors who are completely deficient in MPO fail to form neutrophil extracellular traps (NETs), indicating that MPO is required for NET formation. In contrast, neutrophils from partially MPO-deficient donors make NETs, and pharmacological inhibition of MPO only delays and reduces NET formation. Extracellular products of MPO do not rescue NET formation, suggesting that MPO acts cell-autonomously. Finally, NET-dependent inhibition of Candida albicans growth is compromised in MPO-deficient neutrophils. The inability to form NETs may contribute in part to the host defense defects observed in completely MPO-deficient individuals.     

中性粒细胞胞外诱捕网在抗寄生虫免疫中的作用研究进展

中性粒细胞胞外诱捕网（neutrophil extracellular traps, NETs）是活化的炎性中性粒细胞在感染或炎症应答期主动释放的一种串珠样纤维网状物质,由染色质DNA和多种胞内蛋白成分组成,可通过缠绕致病菌限制其扩散,同时通过各种抗菌蛋白杀伤致病菌,被认为是中性粒细胞除吞噬和脱颗粒作用外的第三种杀菌机制。近年研究显示,NETs也参与抗寄生虫免疫过程。本文就NETs在抗寄生虫免疫中作用的研究进展作一综述,以期为寄生虫病发病机制研究以及相关治疗药物开发提供参考。     

Cancers predispose neutrophils to release extracellular DNA traps that contribute to cancer-associated thrombosis

Cancer-associated thrombosis often lacks a clear etiology. However, it is linked to a poor prognosis and represents the second-leading cause of death in cancer patients. Recent studies have shown that chromatin released into blood, through the generation of neutrophil extracellular traps (NETs), is procoagulant and prothrombotic. Using a murine model of chronic myelogenous leukemia, we show that malignant and nonmalignant neutrophils are more prone to NET formation. This increased sensitivity toward NET generation is also observed in mammary and lung carcinoma models, suggesting that cancers, through a systemic effect on the host, can induce an increase in peripheral blood neutrophils, which are predisposed to NET formation. In addition, in the late stages of the breast carcinoma model, NETosis occurs concomitant with the appearance of venous thrombi in the lung. Moreover, simulation of a minor systemic infection in tumor-bearing, but not control, mice results in the release of large quantities of chromatin and a prothrombotic state. The increase in neutrophil count and their priming is mediated by granulocyte colony-stimulating factor (G-CSF), which accumulates in the blood of tumor-bearing mice. The prothrombotic state in cancer can be reproduced by treating mice with G-CSF combined with low-dose LPS and leads to thrombocytopenia and microthrombosis. Taken together, our results identify extracellular chromatin released through NET formation as a cause for cancer-associated thrombosis and unveil a target in the effort to decrease the incidence of thrombosis in cancer patients.     

Leishmania amazonensis promastigotes induce and are killed by neutrophil extracellular traps

Neutrophils are short-lived leukocytes that die by apoptosis, necrosis, and NETosis. Upon death by NETosis, neutrophils release fibrous traps of DNA, histones, and granule proteins named neutrophil extracellular traps (NETs), which can kill bacteria and fungi. Inoculation of the protozoan Leishmania into the mammalian skin causes local inflammation with neutrophil recruitment. Here, we investigated the release of NETs by human neutrophils upon their interaction with Leishmania parasites and NETs'' ability to kill this protozoan. The NET constituents DNA, elastase, and histones were detected in traps associated to promastigotes by immunofluorescence. Electron microscopy revealed that Leishmania was ensnared by NETs released by neutrophils. Moreover, Leishmania and its surface lipophosphoglycan induced NET release by neutrophils in a parasite number- and dose-dependent manner. Disruption of NETs by DNase treatment during Leishmania–neutrophil interaction increased parasite survival, evidencing NETs'' leishmanicidal effect. Leishmania killing was also elicited by NET-rich supernatants from phorbol 12-myristate 13-acetate-activated neutrophils. Immunoneutralization of histone during Leishmania–neutrophil interaction partially reverted Leishmania killing, and purified histone killed the parasites. Meshes composed of DNA and elastase were evidenced in biopsies of human cutaneous leishmaniasis. NET is an innate response that might contribute to diminish parasite burden in the Leishmania inoculation site.     

Ovine vital neutrophil extracellular traps bind and impair Haemonchus contortus L3 in a breed‐dependent manner

This study aimed to characterize neutrophil response to Haemonchus contortus (Hc) in vitro using cells from parasite‐resistant St. Croix (STC) and parasite‐susceptible Suffolk (SUF) sheep. Neutrophils from Hc‐primed and naive STC and SUF sheep were incubated with Hc larval antigen (HcLA), Hc worm antigen (HcWA) or complete media (CM). After HcLA exposure, neutrophils from STC and SUF formed extracellular traps composed of DNA. Stimulation with HcLA induced a 35‐fold increase in extracellular DNA compared to CM controls. However, extracellular DNA was not found when neutrophils were cultured with HcWA. The formation of neutrophil extracellular traps (NET) in response to HcLA yields a low percentage of necrotic cells indicating a form of vital NETosis. Neutrophils from primed and naïve STC bound Hc L3 greater (93% and 68%) than SUF (78% and 45%; P < 0.001). Furthermore, STC neutrophils significantly reduced larval ATP levels compared to SUF neutrophils (0.05 μmol/L vs 0.1 μmol/L ATP, P < 0.001). These data indicate that ovine neutrophils bind, form vital NET and reduce ATP to Hc L3 in a breed and infection status–dependent manner.     

Remission of Granulomatosis with Polyangiitis Only After Resection of a Pulmonary Nodule

Granulomatosis with polyangiitis (GPA) is characterized by necrotizing granulomatous lesions and is classified as ANCA-associated vasculitis (AAV). We herein report a case of GPA that was remitted by resection of a pulmonary lesion without immunosuppressive therapy. We detected activated neutrophils and neutrophil extracellular traps (NET) formation in resected lung tissue by immunofluorescence. Activated neutrophils and NETs might be involved in the pathophysiology of AAV and induce the vicious cycle of ANCAs and NETs. In cases of GPA with no other severe lesions, the reevaluation of the disease activity after diagnostic resection is crucial for considering the need for immunosuppressive therapy.     

Melatonin restores neutrophil functions and prevents apoptosis amid dysfunctional glutathione redox system

Melatonin is a chronobiotic hormone, which can regulate human diseases like cancer, atherosclerosis, respiratory disorders, and microbial infections by regulating redox system. Melatonin exhibits innate immunomodulation by communicating with immune system and influencing neutrophils to fight infections and inflammation. However, sustaining redox homeostasis and reactive oxygen species (ROS) generation in neutrophils are critical during chemotaxis, oxidative burst, phagocytosis, and neutrophil extracellular trap (NET) formation. Therefore, endogenous antioxidant glutathione (GSH) redox cycle is highly vital in regulating neutrophil functions. Reduced intracellular GSH levels and glutathione reductase (GR) activity in the neutrophils during clinical conditions like autoimmune disorders, neurological disorders, diabetes, and microbial infections lead to dysfunctional neutrophils. Therefore, we hypothesized that redox modulators like melatonin can protect neutrophil health and functions under GSH and GR activity–deficient conditions. We demonstrate the dual role of melatonin, wherein it protects neutrophils from oxidative stress-induced apoptosis by reducing ROS generation; in contrast, it restores neutrophil functions like phagocytosis, degranulation, and NETosis in GSH and GR activity–deficient neutrophils by regulating ROS levels both in vitro and in vivo. Melatonin mitigates LPS-induced neutrophil dysfunctions by rejuvenating GSH redox system, specifically GR activity by acting as a parallel redox system. Our results indicate that melatonin could be a potential auxiliary therapy to treat immune dysfunction and microbial infections, including virus, under chronic disease conditions by restoring neutrophil functions. Further, melatonin could be a promising immune system booster to fight unprecedented pandemics like the current COVID-19. However, further studies are indispensable to address the clinical usage of melatonin.     

Neutrophil histone modification by peptidylarginine deiminase 4 is critical for deep vein thrombosis in mice

Deep vein thrombosis and pulmonary embolism are major health problems associated with high mortality. Recently, DNA-based neutrophil extracellular traps (NETs) resulting from the release of decondensed chromatin, were found to be part of the thrombus scaffold and to promote coagulation. However, the significance of nuclear decondensation and NET generation in thrombosis is largely unknown. To address this, we adopted a stenosis model of deep vein thrombosis and analyzed venous thrombi in peptidylarginine deiminase 4 (PAD4)-deficient mice that cannot citrullinate histones, a process required for chromatin decondensation and NET formation. Intriguingly, less than 10% of PAD4^−/− mice produced a thrombus 48 h after inferior vena cava stenosis whereas 90% of wild-type mice did. Neutrophils were abundantly present in thrombi formed in both groups, whereas extracellular citrullinated histones were seen only in thrombi from wild-type mice. Bone marrow chimera experiments indicated that PAD4 in hematopoietic cells was the source of the prothrombotic effect in deep vein thrombosis. Thrombosis could be rescued by infusion of wild-type neutrophils, suggesting that neutrophil PAD4 was important and sufficient. Endothelial activation and platelet aggregation were normal in PAD4^−/− mice, as was hemostatic potential determined by bleeding time and platelet plug formation after venous injury. Our results show that PAD4-mediated chromatin decondensation in the neutrophil is crucial for pathological venous thrombosis and present neutrophil activation and PAD4 as potential drug targets for deep vein thrombosis.     

Distribution of histamine among leukocytes and platelets

1. Platelets and lymphocytes free of other white elements of blood have beenanalysed for histamine by a microchemical method. Platelets were found to contain 1280 µg. per liter or .009 µg. per 10⁹ platelets, lymphocytes 2600 µg. perliter, or 0.6 µg. per 10⁹ cells.

2. The histamine content of neutrophilic, eosinophilic and basophilic granulocytes has been calculated by multiple regression from histamine measurementson one series of blood samples from normal adults and another from subjectswith chronic myelocytic leukemia. The normal values are 1080 µg. per l0⁹basophils and 160 µg. per 10⁹ eosinophils or 2,400,000 and 360,000 µg. per literrespectively. The corresponding values for neutrophils are 3 µg. per 10⁹ cellsand 7000 µg. per liter. The values for the histamine concentration per cell arestatistically significant for basophils and eosinophils, but not for neutrophils.

In the leukemia series, the values for neutrophils and basophils are respectively69 and 305 µg. per 10⁹ cells, and they are statistically significant. The differencefrom normal in the value for basophils was not statistically validated. There are,however, in chronic myelocytic leukemia, histological changes from the normalthat are consonant with a decreased histamine content in basophils and an increased histamine content in eosinophils and neutrophils.

3. Although definite values for the histamine content of monocytes and theimmature forms seen in chronic myelocytic leukemia have not been obtained,there is reason to believe that the histamine of these cell types does not exceedthat of neutrophils.

4. By centrifuging white cells in a specific gravity gradient column, partialsegregation of cell types was obtained. Peak concentrations were observed at thefollowihig specific gravities: lymphocytic leukemia lymphocytes, 1.063; myelocytes, normal lymphocytes and basophils, all near 1.070; neutrophils, 1.080,and eosinophils, 1.080 or higher. Although individual concentration peaks wereusually quite sharp, there was considerable overlapping at intermediate specificgravities.

5. About half of the histamine of normal blood is in the basophils, one-thirdin the eosinophils and the remaining one-sixth in all the other blood elementscombined. In blood samples from patients with chronic myelocytic leukemia,the fraction of blood histamine carried by each type of granulocyte varies widely.

Submitted on September 20, 1954 Accepted on October 11, 1954