Diversity Of Gut Microbiota Associated With Patients With Major Depressive Disorder

Part1Molecular analysis of the diversity of gut microbiota associated with patients with major depressive disorderMajor depressive disorder (MDD) is characterized by a combination of symptoms that interfere with a person’s ability to work, sleep, study, eat, and enjoy once-pleasurable activities. Studies using animal models have shown that depression affects the stability of the microbiota, but the actual structure and composition in patients with major depressive disorderare not well understood.Here, we analyzed fecal samples from patients with depression. High-throughput pyrosequencing showed that, according to the Shannon index, increased fecal bacterial a-diversity was found in the MDD vs. the HC group. Bacteroidetes, Proteobacteria, and Actinobacteria strongly increased in level, whereas that of Firmicutes was significantly reduced in the MDD compared with the HC group. Despite profound interindividual variability, levels of several predominant genera were significantly different between the MDD and HC groups. At genus level, the relative proportions of Acidaminococcaceae, Enterobacteriaceae, Fusobacteriaceae, Porphyromonadaceae, and Rikenellaceae were significantly higher in the MDD group compared with the HC group; we also found significantly lower levels of Bacteroidaceae, Erysipelotrichaceae, Lachnospiraceae, Prevotellaceae, Ruminococcaceae, and Veillonellaceae in the MDD than in the HC group. Most notably, the MDD groups had increased levels of Enterobacteriaceae and Alistipes but reduced levels of Faecalibacterium. A negative correlation was observed between Faecalibacterium and the severity of depressive symptoms. These findings enable a better understanding of changes in the fecal microbiota composition in such patients, showing either a predominance of some potentially harmful bacterial groups or a reduction in beneficial bacterial genera. Further studies are warranted to elucidate the temporal and causal relationships between gut microbiota and depression and to evaluate the suitability of the microbiome as a biomarker. Part2Partially Restoration of Gut Microbiota in Patients with Major Depressive Disorder after Responded to AntidepressantIn order to explore the changes of gut microbiota in the course of depression, we analyzed the structure of24fecal samples from12patients before or after responded to antidepressant treatment by pyrosequencing16S RNA genes. We found that the relative abundance of Bacteroidaceae was significantly increased after patients responded to antidepressant therapy; these findings also shown either a reduction of some potentially harmful bacterial groups or an increase in beneficial bacterial genera. Notablely, the metagenome analysis LefSe approach was also applied to identify Faecalibacterium as a biomarker for patients responded to antidepressant treatment.