肠道菌群失调在抑郁症发病中的作用与机制研究

Depression is a psychiatric disease with high incidence and mortality retes, its pathogenesis is very complicated and not completely clear. Although new researches confirmed altered fecal microbiota composition in patients with depression, the role of specific gut microbes in the development of depression remains unclear. Human-flora associated (HFA) animal provide an attractive model for studying the interrelations between diseases and the gut microbiota. Fecal samples from adult female twin pairs discordant for depression have been collected in our previous preliminary work. In present study, we transplant the intact human fecal microbiota from each member of a discordant twin pair into separate groups of recipient germfree rat, use high-throughput sequencing technologies to test the donors' communities to be replicated and identify the differences between their composition; we also observed the impact of these differences on body weight, depression-associated behavioral manifestations, tight junction protein claudin in colon, cortisol and proinflammatory cytokines in serum, monoamine neurotransmitter and their metabolites in serum and hippocampus after HFA rat exposed to chronic stress. According to the study, we will understand the role of specific gut microbes in the development of depression, which will screen out the depression-associated key functional bacteria and provide a scientific basis for the prevention and treatment of depression.

抑郁症是一种高发病率和高致死率的精神疾病，其发病机制复杂。最新研究证实，肠道菌群失衡与抑郁症的发病密切相关。我们前期研究发现，抑郁症患者存在不同程度的肠道菌群失衡，但未能揭示特定肠道微生物在抑郁症发生发展中的作用。人源化肠道菌群（HFA）动物模型是研究肠道菌群与疾病相关性的理想模型，项目组前期已收集单卵双胎不协调抑郁症的粪便标本并制备了相应的菌群标本。本课题拟以无菌大鼠为研究对象，建立接种单卵双胎不协调抑郁症HFA大鼠模型，采用高通量测序技术评价人肠道菌群在无菌大鼠肠道内定植效果，并解析其肠道菌群的结构特征；观察肠道菌群差异对慢性应激下HFA大鼠体重、抑郁症相关行为、结肠组织中紧密连接蛋白的表达、血清皮质酮和细胞因子、血清和海马内单胺类神经递质及其代谢产物的影响，阐明肠道菌群在抑郁症发病中的作用及其机制，并筛选出与抑郁症发生发展密切相关的关键功能菌，为抑郁症的防治提供新思路和新途径。

目的：肠道菌群在抑郁症发病过程中起着重要作用,而以往的研究主要以描述性为主，并且不能揭示肠道菌群失衡是抑郁症的发病原因还是结果。本课题拟解析一对同卵双胎不协调抑郁肠道菌群结构差异，并通过粪菌移植技术，从抑郁症发病机制方面明确肠道菌群在抑郁症发病中的作用与机制。.方法：利用高通量测序技术解析同卵双胎不协调抑郁肠道菌群差异，利用人源化肠道菌群动物模型，观察粪菌移植后小鼠肠道菌群差异对慢性应激下HFA大鼠抑郁症相关行为学表现、神经内分泌、免疫、单胺类神经递质及其代谢产物的影响。.结果：我们发现与健康对照相比，患病双胞胎A抑郁急性期肠道菌群中有益菌如Faecalibacterium细菌比例明显减少，而机会致病菌肠杆菌科比例明显增加。但随着抑郁症状的缓解,同卵双胞胎间肠道菌群的相似度逐渐恢复。然后我们将采集的双胞胎粪便制作成粪菌悬液，通过灌胃的方式将供体的粪便接种于伪无菌大鼠肠道内，并接受连续21天长期慢性刺激。结束慢性刺激7天后对大鼠进行行为学评估，然后处死检测大鼠相关炎症因子、皮质酮、神经递质及其代谢产物的检测。抑郁症组较健康组炎症因子（IL-6、TNF-α、CRP）水平明显增高；犬尿酸/色氨酸比率也明显增高；皮质酮也明显上升。.结论：我们的研究证实了肠道菌群失衡是抑郁症发生的重要外源促发因素，可能通过免疫，神经递质代谢及HPA的调节对抑郁症产生影响。