PAD4参与中性粒细胞胞外诱捕网的抗菌作用

蛋白质精氨酸脱亚氨酶4(PAD4)是中性粒细胞胞外诱捕网(NET)介导的细菌杀灭途径中的重要免疫因子。PAD4催化组蛋白瓜氨酸化,促进细菌感染期中性粒细胞形成NET。PAD4/中性粒细胞在炎性因子或细菌作用下不能形成NET,PAD4/鼠相对于PAD4+/+鼠更易受细菌感染。     

中性粒细胞在肿瘤微环境、肿瘤发生发展及诊治中的作用

中性粒细胞是循环系统中最丰富的白细胞,是肿瘤微环境的重要组成部分.中性粒细胞参与肿瘤发生发展过程中的不同阶段,包括肿瘤的发生、增殖和转移.肿瘤微环境中的中性粒细胞群体表现出异质性表型和功能多样性,在肿瘤微环境中扮演促瘤或抑瘤双重角色.本综述重点阐述中性粒细胞在肿瘤微环境中的募集、异质性和极化性,在肿瘤发生发展中及其在临...     

病原体逃逸中性粒细胞胞外诱捕网机制

中性粒细胞胞外诱捕网（NETs）是新发现的中性粒细胞抗病原机制,是天然免疫系统的重要组成部分。但病原体在进化中形成了针对NETs的免疫逃逸机制。不同的病原体逃逸NET的机制不同,本文主要介绍3种机制：降解NETs-DNA、表面分子机制和NETosis调控。     

中性粒细胞胞外诱捕网与肺部炎症性疾病的关系

中性粒细胞募集/浸润是肺部炎症性疾病的特征性表现,是肺部抵抗病原微生物入侵的第一道防线,主要通过吞噬作用杀灭病原微生物.然而,新近的研究发现,中性粒细胞被刺激后可形成一种以DNA为骨架并镶嵌有大量活性蛋白质的网状物质——中性粒细胞胞外诱捕网(neutrophil extracellular traps,NETs),这种特殊形式的生物结构能捕获并杀灭病原微生物.尽管就NETs的生物学功能而言,其对肺部炎症性疾病应该是有益的,但是越来越多的研究表明,NETs对肺上皮细胞和内皮细胞均具有直接的细胞毒性作用,并可能促进肺部炎症性疾病的发生发展.为了系统地了解NETs与肺部相关炎症性疾病的关系,本综述首先简述了NETs的结构、功能和形成过程,然后分别叙述了NETs与哮喘、慢性阻塞性肺病、细菌性肺炎、肺结核、肺囊性纤维化、间质性肺疾病、流感病毒感染和急性肺损伤的关系.最后总结、展望了NETs在肺部炎症性疾病中的潜在研究方向和针对性治疗策略.     

Different procedures of diphenyleneiodonium chloride addition affect neutrophil extracellular trap formation

A unique strategy, in which invading microorganisms are being caught in web-like structures composed mainly of DNA, involves a recently described phenomenon called NETosis. This process seems to be related to the production of reactive oxygen species (ROS). In our study, the influence of diphenyleneiodonium chloride (DPI), which diminishes ROS production, was assessed in the context of neutrophil extracellular trap (NET) release. According to protocol, two distinguished procedures were compared, the first one involving DPI elimination from sample before cell activation and the second one proceeding without the step of inhibitor washout. The kinetics of DNA release was monitored by fluorometric assay, and NET formation was observed by fluorescent microscopy. The addition of DPI to the sample led to a reduction of extracellular DNA release. The strongest inhibition was noticed after treatment with 10 μM DPI, which was removed from medium before stimulation with phorbol-12-myristate-13-acetate (PMA). Our findings confirmed that DPI is able to block NET creation. However, the addition of DPI together with PMA or the addition of inhibitor initially and then washing it out before stimulation resulted in different levels of NET formation. Finally, DPI that remained in the system induced specific morphological changes in the neutrophils' nuclei that was not observed in the DPI washed out from sample.     

Calmodulin-dependents stimulation of the NADPH oxidase of human neutrophils

The NADPH oxidase of human neutrophils is highly sensitive to calcium concentration and is inhibited in intact cells and cell-free preparations by various phenothiazine drugs. Addition of calmodulin to preparations of NADPH oxidase stimulates enzymatic rates from 1.4–2.5-fold. Addition of calmodulin and calcium, but not calcium alone, to NADPH oxidase preparations which have been inactivated by EDTA results in the restoration of activity. No activation is observed when membrane preparations containing latent NADPH oxidase are exposed to calcium and calmodulin. These studies suggest a role for calmodulin in the control of NADPH oxidase but that calmodium alone is not sufficient for activation.     

A non‐redundant role for MKP5 in limiting ROS production and preventing LPS‐induced vascular injury

There are at least 11 mitogen-activated protein kinase (MAPK) phosphatases (MKPs) and only 3 major groups of MAPKs, raising the question of whether these phosphatases have non-redundant functions in vivo. Using a modified mouse model of local Shwartzman reaction, we found that deletion of the MKP5 gene, but not the MKP1 gene, led to robust and accelerated vascular inflammatory responses to a single dose of LPS injection. Depletion of neutrophils significantly reduced the vascular injury in Mkp5^−/− mice, whereas adoptive transfer of Mkp5^−/− neutrophils replicated the LPS-induced skin lesions in wild-type recipients. Neutrophils isolated from Mkp5^−/− mice exhibited augmented p38 MAPK activation and increased superoxide generation on activation. The p38 MAPK inhibitor, SB203580, significantly reduced p47^phox phosphorylation and diminished superoxide production in neutrophils. p38 MAPK phosphorylated mouse p47^phox, and deletion of the p47^phox gene ablated the LPS-induced vascular injury in Mkp5^−/− mice. Collectively, these results show an earlier unrecognized and non-redundant function of MKP5 in restraining p38 MAPK-mediated neutrophil oxidant production, thereby preventing LPS-induced vascular injury.