Sur1-Trpm4 regulation of the pro-inflammatory astrocytic secretome in EAE

背景：中枢神经系统的先天免疫反应在多发性硬化症的疾病进展中起着关键作用。 硬化症(MS)/实验性自身免疫性脑脊髓炎(EAE)。星形胶质细胞、小胶质细胞和促炎性细胞 单核细胞积极促进神经变性、脱髓鞘和疤痕形成，但治疗策略 以神经胶质细胞为靶点仍然难以捉摸。EAE中的反应性星形胶质细胞(这里简称EAE-星形胶质细胞) 脊髓分泌许多促炎因子，单独抑制每种因子是有益的。 在EAE。虽然单独针对促炎因子可能是有益的，但更有希望的策略是 可能更广泛地针对EAE-星形胶质细胞的促炎分泌体。这个想法是从 发表了口服多发性硬化症药物和鞘氨醇-1-磷酸(S1P)受体调节剂Fingolimod的研究成果 研究表明，星形胶质细胞在Fingolimod存在的情况下激活，产生的分泌体不那么有利于... 煽动性的。我们实验室最近发现Sur1-Trpm4在MS/EAE中的病理参与。在慢性病期间 在EAE时相，Sur1-Trpm4通道主要由反应性星形胶质细胞(EAE- 星形胶质细胞)，SUR1的全局抑制减少了几种促炎因子的分泌 细胞因子/趋化因子，减少临床症状、脱髓鞘和轴突丢失。新的实验已经 对这项工作进行了扩展，揭示了Sur1-Trpm4和S1P信号之间可能的关键相互作用 EAE-星形胶质细胞。初步数据表明：(1)在EAE中，Sur1-Trpm4、S1P1和S1P3受体高度协同作用； 定位于EAE-星形胶质细胞；(Ii)在EAE中，编码Sur1的星形胶质细胞特异性缺失的Abcc8产生 在培养的星形胶质细胞中，Sur1-Trpm4通道位于其下游， 在培养的星形胶质细胞中，Sur1-Trpm4通道调节转录 大量的促炎因子。我们的中心假设是Sur1-Trpm4通道是 S1P介导的信号使促炎性星形胶质细胞分泌体永久化并导致疾病 MS/EAE中的维护/进展。 描述：这个项目有三个机械目标，都集中在EAE中的Sur1-Trpm4。在目标1中，我们将 髓鞘少突胶质细胞糖蛋白(MOG)35-55基因缺失雄性和雌性小鼠EAE的研究 在EAE诱导后不同时间启动的星形胶质细胞中的Sur1，以确定星形胶质细胞Sur1在 EAE的不同阶段。在目标2中，将使用分子和膜片钳实验来演示该作用 Sur1-Trpm4在调节激活的星形胶质细胞分泌体的S1P信号中的作用。在目标3中，分子 实验将用来表征Sur1-Trpm4在调节激活的T细胞核因子中的作用 NFAT介导的细胞因子/趋化因子在激活星形胶质细胞中的转录。这些研究将有助于 星形胶质细胞中Sur1-Trpm4和S1P信号分子相互作用的新机制 从而揭示多发性硬化症的新治疗目标。

BACKGROUND: The innate immune response in the CNS plays a critical role in disease progression in multiple sclerosis (MS)/ experimental autoimmune encephalomyelitis (EAE). Astrocytes, microglia, and pro-inflammatory monocytes actively promote neurodegeneration, demyelination and scar formation, but therapeutic strategies targeting glial cells remain elusive. Reactive astrocytes in EAE (here called the “EAE-astrocytes” for short) in the spinal cord secrete numerous pro-inflammatory factors, with inhibition of each factor individually being beneficial in EAE. Whereas targeting pro-inflammatory factors individually may be beneficial, a more promising strategy may be to target the pro-inflammatory secretome of EAE-astrocytes more broadly. This idea emerges from published work with the oral MS drug and sphingosine-1-phosphate (S1P) receptor modulator, fingolimod, in which it was shown that astrocyte activation in the presence of fingolimod, yields a secretome that is less pro- inflammatory. Our lab recently showed pathological involvement of Sur1-Trpm4 in MS/ EAE. During the chronic phase of EAE, Sur1-Trpm4 channels are robustly upregulated predominantly by reactive astrocytes (EAE- astrocytes), with global suppression of SUR1 reducing secretion of several pro-inflammatory cytokines/chemokines, and reducing clinical symptoms, demyelination and axonal loss. New experiments have expanded on this work, revealing what may be a critical interaction between Sur1-Trpm4 and S1P signaling in EAE-astrocytes. Preliminary data show that: (i) in EAE, Sur1-Trpm4, S1P1 and S1P3 receptors are highly co- localized in EAE-astrocytes; (ii) in EAE, astrocyte-specific deletion of Abcc8, which encodes Sur1, yields a secretome similar to that with fingolimod; (iii) in cultured astrocytes, Sur1-Trpm4 channels are downstream of, and are required for, S1P signaling; (iv) in cultured astrocytes, Sur1-Trpm4 channels regulate the transcription of numerous pro-inflammatory factors. Our central hypothesis is that Sur1-Trpm4 channels are required for the S1P-mediated signaling that perpetuates the pro-inflammatory astrocytic secretome and contributes to disease maintenance/progression in MS/ EAE. DESCRIPTION: This project has three mechanistic aims, all focused on Sur1-Trpm4 in EAE. In Aim 1, we will study myelin oligodendrocyte glycoprotein (MOG) 35–55 EAE in male and female mice with genetic deletion of Sur1 in astrocytes, initiated at different times after EAE induction, to establish the role of astrocytic Sur1 at different stages of EAE. In Aim 2, molecular and patch clamp experiments will be used to demonstrate the role of Sur1-Trpm4 in S1P signaling that regulates the secretome of activated astrocytes. In Aim 3, molecular experiments will be used to characterize the role of Sur1-Trpm4 in regulating nuclear factor of activated T-cell (NFAT)-mediated transcription of cytokines/chemokines in activated astrocytes. These studies will contribute new mechanistic insights into the molecular interactions between Sur1-Trpm4 and S1P signaling in astrocytes, and thereby reveal new treatment targets for MS.