A Pilot Exploration of Multi-Omics Research of Gut Microbiome in Major Depressive Disorders

Background: The pathophysiology of major depressive disorder (MDD) remains obscure. Recently, the microbiota-gut-brain (MGB) axis’s role in MDD has an increasing attention. But there are very few studies on the correlations of the gut microbiota with all three omics, including immunology, metabolomics, and brain structure in MDD. Methods: The data of metagenomics, metabolomic, inflammatory factors, and MRI scanning are collected from the two groups including 24 drug-naive MDD patients and 26 healthy controls (HCs). Then, the correlation analysis is performed in all omics. Findings: The results confirmed that there are many markedly altered differences, such as elevated Actinobacteria abundance, plasma IL-1β concentration, lipid, vitamin, and carbohydrate metabolism disorder, and diminished grey matter volume (GMV) of inferior frontal gyrus (IFG) in the MDD patients. Notably, three kinds of discriminative bacteria, Ruminococcus bromii, Lactococcus chungangensis, and Streptococcus gallolyticus have an extensive correlation with metabolome, immunology, GMV, and clinical symptoms. All three microbiota are closely related to IL-1β and lipids (for example, phosphoethanolamine (PEA)). Besides, Lactococcus chungangensis is negatively related to the GMV of left IFG. Interpretation: Overall, this study demonstrate that the effects of gut microbiome exert in MDD is multifactorial. Funding: This work was supported by the National Natural Science Foundation of China (No. 81601182), the grant 2015C03040 of the major subject of Zhejiang Province, and the Natural Science Foundation of Zhejiang Province (LQ20H090010). Declaration of Interest: The authors declare no conflict of interest. Ethical Approval: Ethical approval was obtained from the local Ethics Committee at the First Affiliated Hospital, College of Medicine, Zhejiang University, China.