Interleukin-33 as an immune therapy for stroke

中风是美国退伍军人的主要医疗问题之一。传统的神经中心主义 脑卒中研究中的脑观点可能阻碍了有效疗法的发展。白色物质 (WM)以髓鞘和产生髓鞘的少突胶质细胞（OLs）的损失为特征的损伤是脑损伤的主要原因。 但直到最近才被广泛认识。这些战略能够 需要减轻灰质和WM病理生理学以实现完全的脑保护和长期的 神经恢复越来越多的证据表明，小胶质细胞的不同功能表型/ 巨噬细胞对调节受损脑的炎症状态有相当大的贡献， 影响大脑的完整性具体而言，M2样表型对于组织保存和脑修复是必不可少的 因为M2细胞解决局部炎症，清除细胞碎片，并提供保护因子。 白细胞介素-33（IL-33）是一种多功能细胞因子，参与广泛的免疫应答， 包括增强巨噬细胞中的M2样反应。有趣的是，IL-33及其受体， 由ST 2和IL-1受体辅助蛋白组成，在CNS中表达。IL-33/ST 2的确切作用 然而，缺血性脑中的信号传导还没有得到很好的表征， 仍然未知。我们的初步结果表明，ST 2敲除（KO）小鼠表现出扩大的脑梗死， 短暂性大脑中动脉闭塞（tMCAO）后，WM损伤加重，感觉运动障碍加重。 相比之下，tMCAO后1小时鼻内输注IL-33可减轻脑梗死。值得注意的是，ST 2 KO小鼠 在缺血性脑损伤中，M2样标志物的表达减少，M1样标志物的表达增加。 个脑袋我们已经在体外发现IL-33增强M2极化，特别是在原发性骨髓瘤中IL-10的产生。 小胶质细胞此外，IL-33处理增强了神经元和OL对氧葡萄糖剥夺的存活 (OGD)在神经元-胶质细胞混合培养中，IL-10中和抗体可消除这种作用。 该提议将进一步探索IL-33/ST 2信号转导在缺血性脑损伤后的保护作用， 希望将IL-33开发成一种新的、临床上可行的治疗策略，以改善中风后的大脑 损害我们将测试总体假设，即IL-33/ST 2信号转导的激活可以保护 通过增强小胶质细胞/巨噬细胞向保护性M2表型的极化， 从而限制中风后神经元和WM损伤。测试的具体目标是：目标1：测试 假设IL-33后处理在年轻和老年小鼠中都保护免于局灶性脑缺血。目的 2：检验IL-33/ST 2信号转导通过转移改善缺血性神经元和OL损伤的假设 小胶质细胞向保护性表型转变。目的3：验证IL-10是一种重要的保护因子的假设 由IL-33处理的小胶质细胞释放。这项研究的成功将揭示IL-33作为一种潜在的治疗方法 脑卒中后灰质和WM保护和长期恢复策略。

Stroke is one of the major medical concerns for United States military veterans. The classically neurocentric view of the brain in stroke research may have hindered the development of effective therapies. White matter (WM) injury, characterized by loss of myelin and myelin-producing oligodendrocytes (OLs), is a major cause of functional disability after stroke but has not been widely appreciated until recently. Strategies that are able to alleviate both gray matter and WM pathophysiology are needed to achieve full brain protection and long-term neurological recovery. Accumulating evidence suggests that the different functional phenotypes of microglia/ macrophages contribute considerably to the regulation of inflammatory status of injured brain and ultimately impact the brain integrity. Specifically, M2-like phenotype is essential for tissue preservation and brain repair because M2 cells resolve local inflammation, clear cell debris, and provide protective factors. Interleukin-33 (IL-33) is a multifunctional cytokine that involves in a wide range of immune responses, including potentiating M2-like responses in macrophages. Interestingly, both IL-33 and its receptor, which consists of ST2 and IL-1 receptor accessory protein, are expressed in the CNS. The precise roles of IL-33/ST2 signaling in the ischemic brain, however, are not well-characterized and the underlying mechanisms of action remain unknown. Our preliminary results show that ST2 knockout (KO) mice exhibited enlarged brain infarct, deteriorated WM injury and worse sensorimotor deficits after transient middle cerebral artery occlusion (tMCAO). In contrast, intranasal infusion of IL-33 1h after tMCAO attenuates brain infarct. Remarkably, ST2 KO mice showed reduced expression of M2-like markers and increased expression of M1-like markers in the ischemic brain. We have found in vitro that IL-33 potentiates M2 polarization, especially IL-10 production in primary microglia. Furthermore, IL-33 treatment enhanced neuronal and OL survival against oxygen glucose deprivation (OGD) in neuron-glia mixed culture, which can be abolished by IL-10 neutralizing antibody. This proposal will further explore the protective effect of IL-33/ST2 signaling after ischemic brain injury with the hope of developing IL-33 into a novel, clinically feasible therapeutic strategy to ameliorate post-stroke brain damage. We will test the overarching hypothesis that the activation of IL-33/ST2 signaling protects against cerebral ischemia by enhancing microglia/macrophage polarization toward a protective M2 phenotype, which in turn restricting neuronal and WM injury after stroke. The Specific Aims to be tested are: Aim 1: Test the hypothesis that IL-33 post-treatment protects against focal cerebral ischemia in both young and aged mice. Aim 2: Test the hypothesis that IL-33/ST2 signaling ameliorates ischemic neuronal and OL damage via shifting microglia toward a protective phenotype. Aim 3: Test the hypothesis that IL-10 is an essential protective factor released by IL-33-treated microglia. The success of this study will shed light on IL-33 as a potential therapeutic strategy for both gray matter and WM protection and long-term recovery after stroke.