Division of Epilepsy, Department of Neurological Sciences, University of Nebraska Medical Center, Omaha, Nebraska, USA.
Lankenau Institute for Medical Research, Wynnewood, Pennsylvania, USA.
Epilepsia. 2024 May;65(5):1475-1487. doi: 10.1111/epi.17931. Epub 2024 Mar 12.
We previously demonstrated that interleukin-1 receptor-mediated immune activation contributes to seizure severity and memory loss in anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis. In the present study, we assessed the role of the myeloid differentiation primary response gene 88 (MyD88), an adaptor protein in Toll-like receptor signaling, in the key phenotypic characteristics of anti-NMDAR encephalitis.
Monoclonal anti-NMDAR antibodies or control antibodies were infused into the lateral ventricle of MyD88 knockout mice (MyD88) and control C56BL/6J mice (wild type [WT]) via osmotic minipumps for 2 weeks. Seizure responses were measured by electroencephalography. Upon completion of the infusion, the motor, anxiety, and memory functions of the mice were assessed. Astrocytic (glial fibrillary acidic protein [GFAP]) and microglial (ionized calcium-binding adaptor molecule 1 [Iba-1]) activation and transcriptional activation for the principal inflammatory mediators involved in seizures were determined using immunohistochemistry and quantitative real-time polymerase chain reaction, respectively.
As shown before, 80% of WT mice infused with anti-NMDAR antibodies (n = 10) developed seizures (median = 11, interquartile range [IQR] = 3-25 in 2 weeks). In contrast, only three of 14 MyD88 mice (21.4%) had seizures (0, IQR = 0-.25, p = .01). The WT mice treated with antibodies also developed memory loss in the novel object recognition test, whereas such memory deficits were not apparent in MyD88 mice treated with anti-NMDAR antibodies (p = .03) or control antibodies (p = .04). Furthermore, in contrast to the WT mice exposed to anti-NMDAR antibodies, the MyD88 mice had a significantly lower induction of chemokine (C-C motif) ligand 2 (CCL2) in the hippocampus (p = .0001, Sidak tests). There were no significant changes in the expression of GFAP and Iba-1 in the MyD88 mice treated with anti-NMDAR or control antibodies.
These findings suggest that MyD88-mediated signaling contributes to the seizure and memory phenotype in anti-NMDAR encephalitis and that CCL2 activation may participate in the expression of these features. The removal of MyD88 inflammation may be protective and therapeutically relevant.
我们之前的研究表明，白细胞介素-1 受体介导的免疫激活导致抗 N-甲基-D-天冬氨酸受体（NMDAR）脑炎的癫痫发作严重程度和记忆丧失。在本研究中，我们评估了髓样分化初级反应基因 88（MyD88）在抗 NMDAR 脑炎关键表型特征中的作用，MyD88 是 Toll 样受体信号传导中的一种衔接蛋白。
通过渗透微型泵将抗 NMDAR 抗体或对照抗体输注到 MyD88 敲除小鼠（MyD88）和对照 C56BL/6J 小鼠（野生型[WT]）的侧脑室中 2 周。通过脑电图测量癫痫发作反应。输注完成后，评估小鼠的运动、焦虑和记忆功能。使用免疫组织化学和实时定量聚合酶链反应分别确定与癫痫发作相关的主要炎症介质的星形胶质细胞（胶质纤维酸性蛋白[GFAP]）和小胶质细胞（离子钙结合衔接分子 1[Iba-1]）激活和转录激活。
如前所述，80%输注抗 NMDAR 抗体的 WT 小鼠（n=10）出现癫痫发作（中位数=11，2 周内 IQR=3-25）。相比之下，只有 14 只 MyD88 小鼠中的 3 只（21.4%）出现癫痫发作（0，IQR=0-0.25，p=0.01）。用抗体治疗的 WT 小鼠在新物体识别测试中也出现了记忆丧失，而用抗 NMDAR 抗体或对照抗体治疗的 MyD88 小鼠则没有明显的记忆缺陷（p=0.03，p=0.04）。此外，与接触抗 NMDAR 抗体的 WT 小鼠相比，MyD88 小鼠在海马体中趋化因子（C-C 基序）配体 2（CCL2）的诱导明显降低（p=0.0001，Sidak 检验）。用抗 NMDAR 或对照抗体治疗的 MyD88 小鼠的 GFAP 和 Iba-1 表达没有明显变化。
这些发现表明，MyD88 介导的信号转导导致抗 NMDAR 脑炎的癫痫发作和记忆表型，CCL2 激活可能参与这些特征的表达。消除 MyD88 炎症可能具有保护作用和治疗相关性。
