Department of Laboratory Diagnostics and Clinical Immunology of Developmental Age, Warsaw Medical University, Warsaw, Poland.
Postgraduate School of Molecular Medicine, Warsaw Medical University, Warsaw, Poland.
Adv Exp Med Biol. 2018;1108:1-12. doi: 10.1007/5584_2018_245.
Neutrophils are the first line of immune defense against pathogens. They use three major antimicrobial mechanisms: phagocytosis, degranulation, and release of neutrophil extracellular traps (NETs). NETs are structures which consist of nuclear DNA conjugated with antibacterial proteins. They are formed to entrap and kill pathogens. The aim of the study was to evaluate the influence of Escherichia coli (E. coli), Streptococcus pneumoniae (S. pneumoniae), Stenotrophomonas maltophilia (S. maltophilia), and Pseudomonas aeruginosa (P. aeruginosa), isolated from the peripheral blood of children with sepsis, on the release and degradation of NETs by neutrophils isolated from blood healthy adult subjects. Neutrophils were stimulated with the bacterial strains outlined above. The quantitative and qualitative analyses of NETs release were performed by fluorometric measurement and immunofluorescence, respectively. The ability of bacteria to degrade NETs was studied qualitatively. Oxidative burst was assessed by flow cytometry. Histone H3 citrullination was evaluated by Western blot. We found that NETs were formed only when neutrophils were incubated with S. pneumoniae. E. coli, P. aeruginosa, and S. maltophilia did not induce the release of the NETs. P. aeruginosa, S. pneumoniae, and E. coli induced the production of reactive oxygen species (ROS) by neutrophils. Two studied bacterial strains (S. pneumoniae and E. coli) were able to degrade NETs. However, none of the strains induced the citrullination of histone H3. We conclude that the ability of bacteria to induce and degrade NETs depends on the specific bacterial strain.
中性粒细胞是抵御病原体的第一道免疫防线。它们使用三种主要的抗菌机制：吞噬作用、脱颗粒作用和释放中性粒细胞胞外陷阱（NETs）。NETs 是由与抗菌蛋白结合的核 DNA 组成的结构。它们的形成是为了捕获和杀死病原体。本研究的目的是评估从脓毒症患儿外周血中分离出的大肠杆菌（E. coli）、肺炎链球菌（S. pneumoniae）、嗜麦芽窄食单胞菌（S. maltophilia）和铜绿假单胞菌（P. aeruginosa）对健康成人外周血中性粒细胞释放和降解 NETs 的影响。用上述细菌株刺激中性粒细胞。通过荧光测量和免疫荧光分别进行 NETs 释放的定量和定性分析。研究细菌降解 NETs 的能力为定性研究。通过流式细胞术评估氧化爆发。通过 Western blot 评估组蛋白 H3 瓜氨酸化。我们发现只有当中性粒细胞与肺炎链球菌孵育时才会形成 NETs。大肠杆菌、铜绿假单胞菌和嗜麦芽窄食单胞菌不会诱导 NETs 的释放。铜绿假单胞菌、肺炎链球菌和大肠杆菌诱导中性粒细胞产生活性氧（ROS）。两种研究的细菌株（肺炎链球菌和大肠杆菌）能够降解 NETs。然而，没有一种菌株诱导组蛋白 H3 的瓜氨酸化。我们得出结论，细菌诱导和降解 NETs 的能力取决于特定的细菌株。
