Faculty of Medicine, Department of Medical Biology, Genome and Stem Cell Center (GENKOK), Erciyes University, 38030, Melikgazi, Kayseri, Turkey.
Faculty of Medicine, Department of Pediatrics, Division of Pediatric Hematology-Oncology, Erciyes University, 38030, Melikgazi, Kayseri, Turkey.
J Clin Immunol. 2019 May;39(4):391-400. doi: 10.1007/s10875-019-00632-5. Epub 2019 Apr 25.
Interleukin-2-inducible T cell kinase (ITK) is an important mediator of T cell receptor signaling. Loss of function mutations in ITK results in hypogammaglobulinemia and CD4+ T cell loss in humans, and the patients often present with EBV-associated B cell lymphoproliferative syndrome. Itk-deficient mice show loss of T cell naivety, impaired cytolytic activity of CD8+ T cells, and defects in CD4+ T cell lineage choice decisions. In mice, Itk mutations were shown to affect Th17-Treg lineage choice in favor of the latter. In this study, we explored whether human ITK reciprocally regulates Th17-Treg balance as its murine ortholog.
Whole Exome Sequencing was used to identify the mutation. ITK-deficient peripheral blood lymphocytes were characterized by FACSAria III-based flow cytometric assays with respect to proliferation, apoptosis, cytokine production, and innate lymphoid cell (ILC) frequency. Sorted T cells from healthy donors were exposed to ibrutinib, an irreversible ITK inhibitor, to assess ITK's contribution to Th17 and Treg cell generation and functions.
In this study, we report a child with a novel ITK mutation who showed impaired CD3/CD28 induced proliferation in T cells. ITK-mutant cells were more apoptotic irrespective of TCR activation. More importantly, T cells produced less Th17-associated cytokines IL-17A, IL-22, and GM-CSF. Conversely, Th1-associated IFN-γ production was increased. An irreversible inhibitor of ITK, ibrutinib, blocked ex vivo Th17 generation and IL-17A production, conversely augmented FOXP3 expression only at low doses in Treg cultures. Finally, we analyzed peripheral ILC populations and observed a relative decrease in ILC2 and ILC3 frequency in our ITK-deficient patient.
To our knowledge, this is the first report showing that both genetic and chemical inhibition of ITK result in reduced Th17 generation and function in humans. We also report, for the first time, a reduction in ILC2 and ILC3 populations in an ITK-deficient human patient.
白细胞介素-2 诱导的 T 细胞激酶（ITK）是 T 细胞受体信号转导的重要介质。ITK 功能丧失突变导致人类低丙种球蛋白血症和 CD4+T 细胞丢失，患者常伴有 EBV 相关的 B 细胞淋巴增生综合征。Itk 缺陷小鼠表现出 T 细胞幼稚性丧失、CD8+T 细胞细胞溶解活性受损以及 CD4+T 细胞谱系选择决定缺陷。在小鼠中，Itk 突变被证明影响 Th17-Treg 谱系选择，有利于后者。在这项研究中，我们探讨了人类 ITK 是否像其鼠类同源物一样反向调节 Th17-Treg 平衡。
采用外显子组测序鉴定突变。采用基于 FACSAria III 的流式细胞术分析 ITK 缺陷外周血淋巴细胞的增殖、凋亡、细胞因子产生和固有淋巴细胞（ILC）频率。从健康供者中分选的 T 细胞暴露于不可逆 ITK 抑制剂 ibrutinib，以评估 ITK 对 Th17 和 Treg 细胞生成和功能的贡献。
本研究报道了一名患有新型 ITK 突变的儿童，其表现为 T 细胞 CD3/CD28 诱导增殖受损。无论 TCR 激活与否，ITK 突变细胞凋亡更多。更重要的是，T 细胞产生的 Th17 相关细胞因子 IL-17A、IL-22 和 GM-CSF 减少。相反，Th1 相关 IFN-γ 产生增加。ITK 的不可逆抑制剂 ibrutinib 阻断了体外 Th17 的生成和 IL-17A 的产生，但仅在低剂量时在 Treg 培养物中增加 FOXP3 表达。最后，我们分析了外周 ILC 群体，发现我们的 ITK 缺陷患者中 ILC2 和 ILC3 频率相对降低。
据我们所知，这是第一项表明遗传和化学抑制 ITK 导致人类 Th17 生成和功能降低的报告。我们还首次报告了 ITK 缺陷人类患者中 ILC2 和 ILC3 群体减少。
