Department of Neurology, Beijing Tiantan Hospital; China National Clinical Research Center for Neurological Diseases; Advanced Innovation Center for Human Brain Protection, Beijing Institute of Brain Disorders, Capital Medical University, No.119 South 4th Ring West Road, Fengtai District, Beijing 100070, China.
Department of Neurology, Beijing Tiantan Hospital; China National Clinical Research Center for Neurological Diseases; Advanced Innovation Center for Human Brain Protection, Beijing Institute of Brain Disorders, Capital Medical University, No.119 South 4th Ring West Road, Fengtai District, Beijing 100070, China.
Life Sci. 2020 Oct 1;258:118217. doi: 10.1016/j.lfs.2020.118217. Epub 2020 Aug 6.
Astrocytes expressing the aquaporin-4 (AQP4) water channel are pathogenic, disease specific immunoglobulins (IgG) found in neuromyelitis optica spectrum disorder (NMOSD), referred to as NMO-IgG, which targets astrocytic AQP4. The interleukin-6 (IL-6) signaling when astrocytes were exposed to NMO-IgG present in the serum of NMOSD patients was evaluated.
Serum or human-IgG from NMOSD or healthy controls were exposed to astrocytes. The selectivity and immuno-pathological consequences of Ig binding to surface epitopes were measured by confocal microscopy. Astrocytes were exposed to medium, IL-6, soluble IL-6 receptor (sIL-6R), IL-6 + sIL-6R (IL-6/R), NMO-IgG or control-IgG, NMO-IgG + IL-6/R. The expression of key proteins in IL-6 signaling pathway, IL-6 cytokine and mRNA levels were evaluated by western blotting, enzyme-linked immunosorbent assay and quantitative polymerase chain reaction, respectively.
Serum or NMO-IgG from NMOSD patients both induced the rapid downregulation of AQP4 expression on the surface of astrocytes. Stimulation of astrocytes with NMO-IgG, IL-6/R, and NMO-IgG + IL-6/R resulted in the enhancement of IL-6 mRNA expression. Meanwhile, the exogenous addition of NMO-IgG elicited an inflammatory transcriptional response that involved signaling through the Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) pathway. Inhibition of the IL-6/JAK/STAT3 pathway with the JAK1/2 specific inhibitor, AZD1480, reversed the associated increase of IL-6.
Our findings suggest that NMO-IgG can stimulate the astrocytic JAK1/2/STAT3-dependent inflammatory response, which represents one of the important events in NMO pathogenesis. Inhibition of the JAK1/2 signaling pathway may be a novel promising therapy for NMOSD.
水通道蛋白-4（AQP4）在星形胶质细胞中表达，在视神经脊髓炎谱系疾病（NMOSD）中发现的具有致病性的、疾病特异性的免疫球蛋白（IgG），称为 NMO-IgG，其靶向星形胶质细胞 AQP4。评估了星形胶质细胞暴露于 NMOSD 患者血清中存在的 NMO-IgG 时的白细胞介素-6（IL-6）信号。
将 NMOSD 或健康对照者的血清或人 IgG 暴露于星形胶质细胞。通过共聚焦显微镜测量 Ig 与表面表位结合的选择性和免疫病理后果。将星形胶质细胞暴露于培养基、IL-6、可溶性 IL-6 受体（sIL-6R）、IL-6/sIL-6R（IL-6/R）、NMO-IgG 或对照 IgG、NMO-IgG+IL-6/R。通过 Western blot、酶联免疫吸附测定和定量聚合酶链反应分别评估 IL-6 信号通路中的关键蛋白、IL-6 细胞因子和 mRNA 水平的表达。
NMOSD 患者的血清或 NMOSD-IgG 均可诱导星形胶质细胞表面 AQP4 表达的快速下调。用 NMO-IgG、IL-6/R 和 NMO-IgG+IL-6/R 刺激星形胶质细胞可增强 IL-6 mRNA 表达。同时，外源性添加 NMO-IgG 引起涉及 Janus 激酶/信号转导和转录激活因子 3（JAK/STAT3）通路的炎症转录反应。用 JAK1/2 特异性抑制剂 AZD1480 抑制 IL-6/JAK/STAT3 通路可逆转相关的 IL-6 增加。
我们的研究结果表明，NMO-IgG 可以刺激星形胶质细胞的 JAK1/2/STAT3 依赖性炎症反应，这是 NMO 发病机制中的重要事件之一。抑制 JAK1/2 信号通路可能是 NMOSD 的一种新的有前途的治疗方法。
