基于甘露糖受体调节炎症的茯苓多糖抗抑郁机制研究

Inflammatory mechanisms play a crucial role in the pathomechanisms of depressive disorder. Thus, the use of antiinflammatory agents provides an important approach for improving the antidepressant response. The mannose receptor can bind to sugars terminated in D-mannose or L-fucose, and regulate inflammatory response. Our preliminary studies found that polysaccharides from poria cocos contain mannose and fucose, and have antidepressive and immunosuppressive effects. We speculated the immunosuppressive effects of these polysaccharides might be mediated by the mannose receptor. Thus, this study aims to systematically explore the immunosuppressive and antidepressive mechanisms of polysaccharides from poria cocos. The polysaccharides are purified and characterized by chemical methods. The antidepressive activity of polysaccharides is detected by the tail suspension test and forced swimming test. The inflammation regulation effect of the polysaccharides is analyzed by macrophage and spleen cell model. Both chronic stress and lipopolysaccharide induced depression model are utilized to study the effects of the polysaccharides on the inflammatory system and monoamine neurotransmitter system in the depression model. The binding ability of the polysaccharides with the mannose receptor are tested by fluorescence labeling method and gene knockout mice in vivo and in vitro, respectively. Finally, the inflammatory pathways that mediated the antidepressive effect of the polysaccharides are studied. The accomplishment of this study is expected to has important significance in exploitation of polysaccharide medicine and provide a new approach for the treatment of depression based on inflammatory mechanisms.

炎症反应是抑郁症发生的关键机制，有效调节炎症反应是治疗抑郁症的重要策略。甘露糖受体可通过特异性识别以甘露糖或岩藻糖为末端的配体来调节炎症反应。我们前期研究发现含有甘露糖和岩藻糖的茯苓多糖有显著的抗抑郁效果和免疫抑制作用，推测茯苓多糖可通过结合甘露糖受体起到免疫调节作用。本申请拟以甘露糖受体为切入点，系统研究茯苓多糖抗炎抗抑郁作用机制。采用化学手段对茯苓多糖进行分离纯化和结构解析，明确其结构特点；利用悬尾和强迫游泳实验检测茯苓系列多糖的抗抑郁活性；结合巨噬细胞和脾细胞模型分析茯苓多糖的炎症调节效应；利用慢性应激和脂多糖诱导抑郁症小鼠模型研究多糖对抑郁症动物炎症及单胺神经递质系统的影响；采用荧光标记法和基因缺陷小鼠检测茯苓多糖和甘露糖受体在体内和体外的结合能力，同时解析介导茯苓多糖抗抑郁的炎症通路。本申请的完成为多糖类抗抑郁药物的开发提供理论依据，为以炎症为核心的抑郁症的治疗提供新途径。

炎症反应是抑郁症发生的关键机制，有效调节炎症反应是治疗抑郁症的重要策略。甘露糖受体可通过特异性识别以甘露糖或岩藻糖为末端的配体来调节炎症反应。本项目以甘露糖受体为切入点，系统研究茯苓多糖抗炎抗抑郁作用机制。首先，通过水提醇沉法提取茯苓粗多糖，采用纤维素离子柱层析和凝胶柱层析进行分离纯化得到的两种茯苓纯多糖PCWPW和PCWPS，对其进行结构解析发现含有甘露糖和岩藻糖。然后，利用悬尾和强迫游泳实验检测两种茯苓纯多糖的抗抑郁活性，发现其具有显著的抗抑郁效果。随后，结合巨噬细胞和脾细胞模型分析茯苓多糖的炎症调节效应，结果发现PCWPW和PCWPS主要通过MR-MyD88-NF-κB和MAPK两条通路来激活巨噬细胞分泌细胞因子TNF-α和IL-10，还能够抑制脾细胞增殖。最后，利用慢性不可预见应激抑郁症小鼠模型研究茯苓多糖对抑郁症动物炎症因子和单胺神经递质含量的影响，发现抑郁症小鼠血清中炎症因子TNF-α水平升高，茯苓多糖能够降低抑郁小鼠体内的TNF-α水平，同时增加抑郁模型小鼠脑组织中的5-HT含量。综上所述，茯苓水提多糖可能通过结合细胞表面甘露糖受体激活下游基因通路，抑制炎症水平和增加单胺神经递质含量，进一步发挥抗抑郁功能。本项目的完成为多糖类抗抑郁药物的开发提供理论依据，为以炎症为核心的抑郁症的治疗提供新途径。为了增加茯苓利用率，我们通过碱提取和多步分离纯化，得到三种茯苓碱提纯多糖PCAPS1、PCAPS2和PCAPS5，其能够通过TLR4-MyD88-NF-κB通路来激活巨噬细胞释放细胞因子，促进脾淋巴细胞和T，B细胞增殖，可以用于免疫佐剂或提高免疫力的药物开发。