Division of Molecular Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
Department of Women's and Children's Health, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
J Leukoc Biol. 2018 Dec;104(6):1199-1213. doi: 10.1002/JLB.4A0118-030RR. Epub 2018 Aug 14.
Mutations in the gene JAGN1 were recently discovered in patients with severe congenital neutropenia (SCN). Neutrophils release neutrophil extracellular traps (NETs) consisting of decondensed chromatin decorated with various granular proteins such as neutrophil elastase and myeloperoxidase (MPO) to combat microbial infections. However, whether JAGN1 is required for the formation or function of NETs is not known. Here, we analyzed primary neutrophils from a patient with homozygous JAGN1 mutations with respect to phorbol myristate acetate (PMA)-induced NET formation. NET release was observed, but there appeared to be a reduced level of expression of MPO in the NETs. To study this further, we differentiated HL-60 cells into neutrophil-like cells and silenced JAGN1 expression by transfection with siRNA. These cells remained capable of producing NETs, but MPO expression was severely affected, and NETs released by JAGN1-silenced cells were ineffective in killing Candida albicans. The candidacidal function was restored upon treatment with GM-CSF or addition of MPO. GM-CSF also up-regulated the expression of calprotectin in NETs. Notably, JAGN1 did not impact on N-glycosylation of MPO in neutrophil-like HL-60 cells. These studies shed light on the susceptibility of SCN patients to fungal infections and the role of JAGN1 for the antimicrobial function of neutrophils exerted by NETs.
JAGN1 基因突变最近在严重先天性中性粒细胞减少症（SCN）患者中被发现。中性粒细胞释放包含解聚染色质的中性粒细胞细胞外陷阱（NETs），这些染色质被各种颗粒蛋白（如中性粒细胞弹性蛋白酶和髓过氧化物酶（MPO））修饰，以抵御微生物感染。然而，JAGN1 是否需要 NETs 的形成或功能尚不清楚。在这里，我们分析了具有纯合 JAGN1 突变的患者的原代中性粒细胞，以研究佛波醇肉豆蔻酸酯（PMA）诱导的 NET 形成。观察到 NET 释放，但 NET 中的 MPO 表达水平似乎降低。为了进一步研究这个问题，我们将 HL-60 细胞分化为中性粒细胞样细胞，并通过转染 siRNA 沉默 JAGN1 表达。这些细胞仍然能够产生 NETs，但 MPO 表达受到严重影响，并且 JAGN1 沉默细胞释放的 NETs在杀死白色念珠菌方面无效。用 GM-CSF 处理或添加 MPO 可恢复杀菌功能。GM-CSF 还上调了 NETs 中钙卫蛋白的表达。值得注意的是，JAGN1 对中性粒细胞样 HL-60 细胞中 MPO 的 N-糖基化没有影响。这些研究阐明了 SCN 患者对真菌感染的易感性以及 JAGN1 在 NETs 发挥中性粒细胞抗菌功能中的作用。
