Ingestion of Faecalibaculum for 14 days induced anhedonia-like and depression behaviors of ABX-treated Ephx2KO mice, accompanied by the increased expression of proinflammatory factors, such as interleukin-6 in the blood and reduction of synaptic proteins expression in the prefrontal cortex (Wang et al., 2021). This evidence concerns the gene IL6 and depressive disorder.