Zhang Fangxing, Qi Nana, Zeng Yanyu, Bao Mengying, Chen Yang, Liao Jinling, Wei Luyun, Cao Dehao, Huang Shengzhu, Luo Qianqian, Jiang Yonghua, Mo Zengnan
Center for Genomic and Personalized Medicine, Guangxi Medical University, Nanning, China.
Guangxi Key Laboratory of Genomic and Personalized Medicine, Nanning, China.
Front Microbiol. 2020 Oct 7;11:557342. doi: 10.3389/fmicb.2020.557342. eCollection 2020.
Altered composition of the gut microbiota has been observed in many neurodegenerative diseases. LanCL1 has been proven to protect neurons and reduce oxidative stress. The present study was designed to investigate alterations of the gut microbiota in LanCL1 knockout mice and to study the interactions between gut bacteria and the brain. Wild-type and LanCL1 knockout mice on a normal chow diet were evaluated at 4 and 8-9 weeks of age. 16s rRNA sequence and untargeted metabolomics analyses were performed to investigate changes in the gut microbiota and feces metabolites. Real-time polymerase chain reaction analysis, AB-PAS staining, and a TUNEL assay were performed to detect alterations in the gut and brain of knockout mice. The serum cytokines of 9-week-old knockout mice, which were detected by a multiplex cytokine assay, were significantly increased. In the central nervous system, there was no increase of antioxidant defense genes even though there was only low activity of glutathione S-transferase in the brain of 8-week-old knockout mice. Interestingly, the gut tight junctions, zonula occludens-1 and occludin, also displayed a downregulated expression level in 8-week-old knockout mice. On the contrary, the production of mucus increased in 8-week-old knockout mice. Moreover, the compositions of the gut microbiota and feces metabolites markedly changed in 8-week-old knockout mice but not in 4-week-old mice. Linear discriminant analysis and -tests identified as a specific abundant bacteria in knockout mice. Quite a few feces metabolites that have protective effects on the brain were reduced in 8-week-old knockout mice. However, N-acetylsphingosine was the most significant downregulated feces metabolite, which may cause the postponement of neuronal apoptosis. To further investigate the effect of the gut microbiota, antibiotics treatment was given to both types of mice from 5 to 11 weeks of age. After treatment, a significant increase of oxidative damage in the brain of knockout mice was observed, which may have been alleviated by the gut microbiota before. In conclusion, alterations of the gut microbiota and feces metabolites alleviated oxidative damage to the brain of LanCL1 knockout mice, revealing that an endogenous feedback loop mechanism of the microbiota-gut-brain axis maintains systemic homeostasis.
在许多神经退行性疾病中都观察到肠道微生物群的组成发生了改变。LanCL1已被证明可以保护神经元并减少氧化应激。本研究旨在调查LanCL1基因敲除小鼠肠道微生物群的变化，并研究肠道细菌与大脑之间的相互作用。对正常饮食的野生型和LanCL1基因敲除小鼠在4周龄和8 - 9周龄时进行评估。进行16s rRNA序列分析和非靶向代谢组学分析，以研究肠道微生物群和粪便代谢物的变化。进行实时聚合酶链反应分析、AB - PAS染色和TUNEL检测，以检测基因敲除小鼠肠道和大脑的变化。通过多重细胞因子检测发现，9周龄基因敲除小鼠的血清细胞因子显著增加。在中枢神经系统中，尽管8周龄基因敲除小鼠大脑中的谷胱甘肽S - 转移酶活性较低，但抗氧化防御基因并没有增加。有趣的是，8周龄基因敲除小鼠的肠道紧密连接蛋白，即闭合蛋白 - 1和闭合蛋白，表达水平也下调。相反，8周龄基因敲除小鼠的黏液分泌增加。此外，8周龄基因敲除小鼠的肠道微生物群组成和粪便代谢物明显改变，而4周龄小鼠则没有。线性判别分析和检验确定某一种菌为基因敲除小鼠中一种特定的优势菌。8周龄基因敲除小鼠中，不少对大脑有保护作用的粪便代谢物减少。然而，N - 乙酰鞘氨醇是下调最显著的粪便代谢物，这可能导致神经元凋亡延迟。为了进一步研究肠道微生物群的作用，在5至11周龄时对两种小鼠都进行了抗生素治疗。治疗后，观察到基因敲除小鼠大脑中的氧化损伤显著增加，而之前这种损伤可能已被肠道微生物群缓解。总之，肠道微生物群和粪便代谢物的改变减轻了LanCL1基因敲除小鼠大脑的氧化损伤，揭示了微生物群 - 肠道 - 脑轴的内源性反馈回路机制维持全身稳态。
