Abstract：
Patients affected by glioma frequently suffer of epileptic discharges, however the causes of brain tumor-related epilepsy (BTRE) are still not completely understood. We investigated the mechanisms underlying BTRE by analyzing the effects of exosomes released by U87 glioma cells and by patient-derived glioma cells. Rat hippocampal neurons incubated for 24 h with these exosomes exhibited increased spontaneous firing, while their resting membrane potential shifted positively by 10-15 mV. Voltage clamp recordings demonstrated that the activation of the Na+ current shifted towards more hyperpolarized voltages by 10-15 mV. To understand the factors inducing hyperexcitability we focused on exosomal cytokines. Western Blot and ELISA assays show that TNF-α is present inside glioma-derived exosomes. Remarkably, incubation with TNF-α fully mimicked the phenotype induced by exosomes, with neurons firing continuously, while their resting membrane potential shifted positively. RT-PCR revealed that both exosomes and TNF-α induced over-expression of the voltage-gated Na channel Nav1.6, a low-threshold Na+ channel responsible for hyperexcitability. When neurons were preincubated with Infliximab, a specific TNF-α inhibitor, the hyperexcitability induced by exosomes and TNF-α were drastically reduced. We propose that Infliximab, an FDA approved drug to treat rheumatoid arthritis, could ameliorate the conditions of glioma patients suffering of BTRE.
摘要：
受神经胶质瘤影响的患者经常遭受癫痫放电，然而,脑肿瘤相关癫痫(BTRE)的病因尚不完全清楚.我们通过分析U87神经胶质瘤细胞和患者来源的神经胶质瘤细胞释放的外泌体的作用，研究了BTRE的潜在机制。用这些外泌体孵育24小时的大鼠海马神经元表现出增加的自发放电，而它们的静息膜电位正向移动10-15mV。电压钳记录表明，Na电流的激活向更高的超极化电压偏移了10-15mV。为了了解诱导过度兴奋的因素，我们关注外泌体细胞因子。Western印迹和ELISA分析显示TNF-α存在于神经胶质瘤来源的外泌体内。值得注意的是,与TNF-α孵育完全模拟了外泌体诱导的表型，神经元持续放电，而它们的静息膜电位发生正向变化。RT-PCR显示，外泌体和TNF-α均诱导电压门控Na通道Nav1.6的过表达，后者是负责过度兴奋的低阈值Na通道。当神经元与英夫利昔单抗预孵育时，一种特定的TNF-α抑制剂，外泌体和TNF-α诱导的兴奋过度显著降低。我们建议英夫利昔单抗，FDA批准的治疗类风湿性关节炎的药物，可以改善患有BTRE的神经胶质瘤患者的病情。
