MKP-1介导MAPKs 信号通路及小胶质细胞炎性活化与抑郁症的关系

In recent years, the hypothesis of inflammatory factors in depression has been further investigated, suggesting that there existed microglia inflammatory activation in depression. The inflammatory activation in microglial cells was closely related to mitogen activated protein kinases (MAPKs) which was regulated by Mitogen-activated protein Kinase Phosphatase-1(MKP-1). The MKP-1 level of hippocampus in depressed model rats was found increased significantly in our previous research. In this study, based on the previous research, we use the depressed rats under chronic unpredictable stress (CUS) as research object, with the adoption of animal behavior, molecular/cellular biology, pharmacology and gene regulation, to study the relationship among MKP-1 activation, MAPK signal pathways activation and CUS-induced increased depression-like behaviors of model rats; In addition, we explore the relationship among MKP1 activity, the MAPK family protein levels and microglia inflammatory activation in model rat hippocampus, and get to know the mechanism of MKP-1 and MAPK signal pathway promoting the microglial cell releasing inflammatory cytokines. This project aims to illuminate the preliminarily molecular mechanism of inflammatory activation in microglia cells mediated by MKP-1 through MAPK signal pathway in depression, and to provide supportive evidence for neural immune hypothesis of depression.

近年来抑郁症神经免疫假说得到进一步拓展，研究认为抑郁症存在着小胶质细胞的炎性活化。丝裂原蛋白活化激酶(MAPKs)活性增加与小胶质细胞炎性活化密切相关，而MAPK磷酸酶1(MKP-1)则调控MAPK家族成员的活性。课题组研究发现抑郁模型大鼠海马区MKP-1水平显著增高。在既往研究基础上，本研究以慢性不可预见性应激(CUS)所致抑郁模型大鼠为研究对象，采用动物行为学、分子/细胞生物学、药理学和基因调控等技术方法，研究MKP-1活性增强、MAPK信号通路激活、CUS所致抑郁模型大鼠抑郁样行为增加之间的关系；探讨模型鼠海马区MKP-1活性以及MAPK家族蛋白水平变化与小胶质细胞炎性活化的关系，了解MKP-1及MAPK信号通路促进小胶质细胞炎性因子释放的作用机制。本项目旨在初步明确MKP-1通过MAPK信号通路介导小胶质细胞炎性活化从而参与抑郁症发生的分子机理，为抑郁症神经免疫假说提供支持性证据。

抑郁症神经免疫假说认为小胶质细胞的炎性活化是导致抑郁的原因之一。丝裂原蛋白活化激酶磷酸酶1(MKP-1)可能通过调控丝裂原蛋白活化激酶(MAPKs)活性，从而调控小胶质细胞炎性活化，导致抑郁样行为的出现。本研究以大鼠与BV-2小胶质细胞为研究对象，采用动物行为学、分子/细胞生物学、基因调控等技术方法，研究MKP-1活性增强、MAPK信号通路激活、小胶质细胞炎性活化与大鼠抑郁样行为之间的关系，探讨MKP-1调控抑郁的分子机理，为抑郁症神经免疫假说提供支持性证据。首先，大鼠随机分为6组（对照组，CUMS组，空载组，MKP-1过表达组，CUMS+空载组，CUMS+MKP-1下调组）。考察大鼠抑郁样行为与海马组织中MKP-1、MAPKs相关蛋白及炎症因子IL-6、IL-1β、TNF-α及小胶质细胞标记物Iba1的表达水平。在体外实验中，对BV-2小胶质细胞进行脂多糖LPS(1ug/ml)处理后给予不同浓度Ro-318220抑制MKP-1的表达，分子检测方法相同。本研究发现过表达MKP-1导致抑郁水平显著升高，而下调MKP-1的大鼠则会抵抗CUMS引起的抑郁样行为。抑郁样大鼠海马组织中MKP-1、IL-6、IL1β、TNF-a表达水平升高，P-ERK/ERK表达水平降低，同时该脑区小胶质细胞被显著激活。在BV-2小胶质细胞中，LPS处理会引起MKP-1、P-P65/P65、IL-6、IL-1β、TNF-ɑ表达水平显著升高。使用Ro-318220抑制MKP-1的表达后，P-JNK/JNK、P-ERK/ERK表达水平增高，而P-P65/P65、IL-6、IL-1β、TNF-ɑ表达水平降低。免疫荧光检测出相似的结果。本研究系统地证实了MKP-1与MAPKs信号通路在抑郁发生过程中的重要性，为靶向干预MKP-1及MAPKs信号通路的关键分子治疗抑郁症提供了临床前证据。