Guimarães-Costa Anderson B, Nascimento Michelle T C, Froment Giselle S, Soares Rodrigo P P, Morgado Fernanda N, Conceição-Silva Fátima, Saraiva Elvira M
Departamento de Imunologia, Instituto de Microbiologia Prof. Paulo de Góes, Universidade Federal do Rio de Janeiro, Bloco I, 21941-902, Rio de Janeiro, Brazil.
Proc Natl Acad Sci U S A. 2009 Apr 21;106(16):6748-53. doi: 10.1073/pnas.0900226106. Epub 2009 Apr 3.
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.
中性粒细胞是寿命较短的白细胞，可通过凋亡、坏死和中性粒细胞胞外诱捕网形成（NETosis）而死亡。在通过NETosis死亡时，中性粒细胞会释放出由DNA、组蛋白和颗粒蛋白组成的纤维状陷阱，即中性粒细胞胞外诱捕网（NETs），其可杀死细菌和真菌。将原生动物利什曼原虫接种到哺乳动物皮肤中会导致局部炎症并募集中性粒细胞。在此，我们研究了人类中性粒细胞与利什曼原虫寄生虫相互作用时NETs的释放情况以及NETs杀死这种原生动物的能力。通过免疫荧光在与前鞭毛体相关的陷阱中检测到NET成分DNA、弹性蛋白酶和组蛋白。电子显微镜显示利什曼原虫被中性粒细胞释放的NETs捕获。此外，利什曼原虫及其表面脂磷壁酸以寄生虫数量和剂量依赖性方式诱导中性粒细胞释放NETs。在利什曼原虫-中性粒细胞相互作用期间用脱氧核糖核酸酶处理破坏NETs会增加寄生虫的存活率，证明了NETs的杀利什曼原虫作用。佛波醇12-肉豆蔻酸酯13-乙酸酯激活的中性粒细胞富含NETs的上清液也能引发利什曼原虫的杀伤。在利什曼原虫-中性粒细胞相互作用期间对组蛋白进行免疫中和可部分恢复对利什曼原虫的杀伤，并且纯化的组蛋白可杀死寄生虫。在人类皮肤利什曼病的活检中证实存在由DNA和弹性蛋白酶组成的网状结构。NET是一种先天性反应，可能有助于减轻利什曼原虫接种部位的寄生虫负担。
