BACKGROUND Cytokine storm syndromes (CSSs), including hemophagocytic lymphohistiocytosis (HLH), are increasingly recognized as hyperinflammatory states leading to multiorgan failure and death. Familial HLH in infancy results from homozygous genetic defects in perforin-mediated cytolysis by CD8 T lymphocytes and natural killer (NK) cells. Later-onset CSSs are often associated with heterozygous defects in familial HLH genes, but genetic etiologies for most are unknown. We identified rare dedicator of cytokinesis 8 (DOCK8) variants in patients with CSS. OBJECTIVE We sought to explore the role of CSS patient-derived DOCK8 mutations on cytolytic activity in NK cells and to further study effects of DOCK8 deficiency in murine models of CSSs. METHODS DOCK8 cDNAs from 2 unrelated patients with CSS with different missense mutations were introduced into human NK-92 cells by foamy virus transduction. NK-cell degranulation (CD107a), cytolytic activity against K562 target cells, and IFN-γ production were explored by flow cytometry. A third patient with CSS with DOCK8 mRNA splice acceptor site variant was explored by exon trapping. Dock8-/- mice were assessed for features of CSS (weight loss, splenomegaly, hepatic inflammation, cytopenias, and IFN-γ levels) on challenge with lymphocytic choriomeningitis virus and excess IL-18. RESULTS Both patient DOCK8 missense mutations decreased cytolytic function in NK cells in a partial dominant-negative fashion in vitro. The patient DOCK8 splice variant disrupted mRNA splicing in vitro. Lymphocytic choriomeningitis virus infection promoted CSS in Dock8-/- mice and interacted with excess IL-18, limiting T-cell numbers while promoting CD8 T-cell hyperactivation. CONCLUSIONS Mutations in DOCK8 may contribute to CSS-like hyperinflammatory states by altering cytolytic function in a threshold model of disease.

中文翻译：

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DOCK8 在细胞因子风暴综合征中的作用。


背景 细胞因子风暴综合征 （CSS），包括噬血细胞性淋巴组织细胞增生症 （HLH），越来越被认为是导致多器官衰竭和死亡的高炎症状态。婴儿家族性 HLH 是由于 CD8 T 淋巴细胞和自然杀伤 （NK） 细胞介导的穿孔素介导的细胞溶解中的纯合子遗传缺陷所致。晚发型 CSS 通常与家族性 HLH 基因的杂合缺陷有关，但大多数的遗传病因尚不清楚。我们在 CSS 患者中发现了罕见的胞质分裂专用因子 8 （DOCK8） 变体。目的 探讨 CSS 患者来源的 DOCK8 突变对 NK 细胞溶细胞活性的影响，并进一步研究 DOCK8 缺陷对 CSS 小鼠模型的影响。方法 通过泡沫病毒转导将 2 例具有不同错义突变的无关 CSS 患者的 Dock8 cDNA 引入人 NK-92 细胞。通过流式细胞术探讨 NK 细胞脱颗粒 （CD107a）、对 K562 靶细胞的溶细胞活性和 IFN-γ 的产生。通过外显子捕获探索了第三名具有 DOCK8 mRNA 剪接受体位点变异的 CSS 患者。评估 Dock8-/-小鼠在淋巴细胞性脉络丛脑膜炎病毒攻击和 IL-18 过量时 CSS 特征 （体重减轻、脾肿大、肝脏炎症、血细胞减少和 IFN-γ 水平）。结果 两个患者 DOCK8 错义突变在体外都以部分显性阴性方式降低了 NK 细胞的溶细胞功能。患者 DOCK8 剪接变体在体外破坏了 mRNA 剪接。淋巴细胞性脉络丛脑膜炎病毒感染促进了 Dock8-/- 小鼠的 CSS，并与过量的 IL-18 相互作用，限制了 T 细胞数量，同时促进了 CD8 T 细胞过度激活。 结论 DOCK8 突变可能通过改变疾病阈值模型中的溶细胞功能而导致 CSS 样高炎症状态。