ERβ选择性激动剂通过调控小胶质细胞MHC Ⅱ而改善多发性硬化模型炎症的研究

Multiple sclerosis (MS) is an autoimmune, demyelinating, and neurodegenerative disease of the central nervous system (CNS) that affects 2–2.5 million people worldwide. While the etiology of MS is not known, it is widely considered to be an autoimmune disease. Currently approved MS drugs reduce relapse rates but fail to reverse or prevent neurodegeneration and disability progression. More and more evidence indicate that microglia and MHC Ⅱ expressed in them, and T cells play important roles in the pathophysiology of MS. In order for CD4+ T cells to contribute to CNS pathogenesis, they must be reactivated with antigen presenting cells within the CNS parenchyma. Susceptibility to EAE and MS is associated with the major histocompatibility complex class Ⅱ (MHC Ⅱ) genes, suggesting that presentation of antigens on MHC Ⅱ plays an important role in CD4+ T cell reactivation and disease initiation. We observed that the ERβ-selective agonist LY3201 could suppress reactivation of T cells invading the spinal cord, which reduced the severity of symptoms, and also decreased mortality in the first 2 weeks after disease onset. However, the mechanism of the ERβ-selective agonist regulated the expression of MHC Ⅱ in microglia and its subsequent role on reactivation of T cells is still unclear. Therefore, we hypothesize that ERβ-selective agonist inhibits MHC Ⅱ expression in microglia via inhibition of major histocompatibility class Ⅱ transactivator（CⅡTA） expression by a mechanism involving inhibition of IFNγ regulatory factor-1 (IRF-1) translocation to the nucleus, which finally inhibits the inflammatory response and symptoms in MS model. The in vivo and in vitro experiments including methods of cell culture and Chromatin immunoprecipitation (ChIP) will be utilized to investigate and answer this hypothesis. The answer of it will surely contribute to the screening of highly ERβ-selective agonist to treat MS.

多发性硬化（MS）是一类中枢神经系统脱髓鞘性自身免疫性疾病，发病原因不甚清楚，治疗效果仍不理想。小胶质细胞及其表达的MHC Ⅱ，以及T细胞参与了MS的整个病程。申请者的前期研究发现雌激素受体β (ERβ) 选择性激动剂通过抑制T细胞的激活而改善MS模型的症状和死亡率。但ERβ选择性激动剂是如何调控小胶质细胞MHC Ⅱ的表达及其在CD4+ T细胞再激活中的作用仍不清楚。由于干扰素调节因子-1（IRF-1）及其调控的MHC Ⅱ反式激活因子（CⅡTA）是MHC Ⅱ转录的主要调节因子。因此，我们推测ERβ选择性激动剂有可能通过抑制IRF-1的核转移而调控CⅡTA的转录，从而进一步抑制MHC Ⅱ的表达和CD4+ T细胞的再激活，最终改善MS模型的炎症和症状。本项目拟通过体内和体外实验来验证这个假设，为进一步的筛选ERβ选择性激动剂用于治疗MS提供研究思路和基础。

多发性硬化（MS）是中枢神经系统（CNS）的一种自身免疫性、脱髓鞘性和神经退行性疾病，该病影响了全球大约200-250万人。尽管多发性硬化的病因尚不明确，但广泛认为多发性硬化是一种自身免疫性疾病。目前批准的多发性硬化药物可降低复发率，但不能逆转或阻止神经退行性疾病和残疾发展。越来越多的证据表明，小胶质细胞和表达于其的主要组织相容性复合体II（MHC II）在多发性硬化的发病中扮演了极为重要的角色。已有的大量文献表明，在T细胞参与多发性硬化的发病过程中，T细胞必须通过CNS实质内的抗原呈递细胞将其重新激活；并且多发性硬化的易感性与MHC II基因密切相关，这表明MHC II上抗原的呈递在CD4 + T细胞的再次激活和疾病引发中起至关重要的作用。我们课题组在PNAS上首次报道了ERβ选择性激动剂可以抑制EAE动物模型脊髓中T细胞的再激活，从而降低症状的严重性并降低疾病发作后前2周的死亡率。但是，我们尚不清楚ERβ-选择性激动剂调节小胶质细胞中MHC II表达的机制。因此，我们在立项时根据自有研究成果和同行研究结果推测ERβ选择性激动剂可以通过抑制II类反式激活因子（CIITA）的表达和抑制IFNγ调节因子（IRF-1）向细胞核的转移，从而抑制小胶质细胞中的MHC II表达、多发性硬化模型中的炎症反应和引发的症状。在本研究中，我们在EAE小鼠模型中使用了ERβ选择性激动剂DPN来证明ERβ选择性激动剂DPN的确可以通过抑制CIITA表达的机制来抑制小胶质细胞中MHC II的表达，其机制涉及抑制IRF-1的核转位，从而抑制了多发性硬化模型中的炎症反应和症状。这些发现可能有助于我们或同行进一步开发或筛选用于治疗多发性硬化的高ERβ选择性激动剂。