Prenatal depression-associated gut microbiota induces depressive-like behaviors and hippocampal neuroinflammation in germ-free mice.

Numerous studies have described the role of the microbiome-gut-brain axis in depression. However, the molecular mechanisms underlying the involvement of gut microbiota in the development of prenatal depression are limited. In this study, fecal microbiota from women with prenatal depression was transplanted into germ-free mice to investigate the potential causal relationships between the gut microbiota and depressive phenotypes. Shotgun metagenomic sequencing and untargeted metabolomics approaches were used to investigate the characteristics of gut microbiota and microbial metabolites. The levels of neuroinflammation in the brain were detected using immunofluorescence and real-time quantitative PCR. We found significant changes in gut microbiota composition and metabolites in mice with fecal microbiota transplantation (FMT) from women with prenatal depression, including decreased Ligilactobacillus, increased Akkermansia, and abnormal glycerophospholipid metabolism. Besides, significant increase in plasma lipopolysaccharide (LPS) levels and significant proliferation of microglia in the hippocampus were observed in mice receiving FMT from women with prenatal depression, accompanied by a significant increase in the expression of nuclear factor-κB (NF-κB) p65, tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) mRNA. The gut microbiota and its metabolites were strongly associated with depressive-like behaviors, plasma LPS and neuroinflammation. Our study collectively demonstrates that dysbiosis of the gut microbiota may play a causal relationship in the development of prenatal depression. This process potentially involves the activation of neuroinflammation through the LPS-NF-κB signaling pathway.