BackgroundGut microbiota can affect human behavior and mood in many ways. Several studies have shown that patients with depression were also accompanied with gut microbiota disorder, in which Firmicutes are related to the protective function of intestinal barrier. In this study, we explore the changes and effects of Firmicutes in the patients with major depressive disorder (MDD).MethodWe recruited 54 subjects, including 27 patients with MDD. Fecal samples were collected for identification by 16S rRNA sequencing and bioinformatics analysis.ResultsThe study shows that the alpha diversity indices of MDD patients are lower than those of the healthy controls. Firmicutes is the most significantly decreased phylum in the MDD samples. There are totally 13 taxonomic biomarkers with P-value <0.01 from Firmicutes. There are differences in 17 KEGG pathways between the two groups.ConclusionThis study found that there is a significant disorder of gut microbiota in the patients with depression, in which the Firmicutes decreased significantly. Defects of the Firmicutes may lead to the depression in short-chain fatty acids, which could account for the physiological basis of low-level inflammation of depression.LimitationsThis is a cross-sectional study and the sample size is comparatively small. Though several diet-related factors were controlled in the study, there is no quantified assessment of it.

Fermented foods play important roles in diets worldwide and account for approximately one-third of all foods and beverages consumed. To date, traditional fermentation has used spontaneous fermentation. The microbiome in fermentation has direct impacts on the quality and safety of fermented foods and contributes to the preservation of traditional methods. Here, we used an integrated meta-omics approach to study the microbiome in the fermentation of pu-erh tea, which is a well-known Chinese fermented food with a special flavor and healthful benefits. This study advanced the knowledge of microbiota, metabolites, and enzymes in the fermentation of pu-erh tea. These novel insights shed light onto the complex microbiome in pu-erh fermentation and highlight the power of integrated meta-omics approaches in understanding the microbiome in food fermentation ecosystems.

The imbalance between pathogenic and beneficial species of the intestinal microbiome and metabolism in rheumatoid arthritis (RA) remains unclarified. Here, using shotgun-based metagenome sequencing for a treatment-naïve patient cohort and a “quasi-paired cohort” method, we observed a deficiency of butyrate-producing species and an overwhelming number of butyrate consumers in RA patients. These outcomes mainly occurred in patients with positive ACPA, with a mean AUC of 0.94. This panel was also validated in established RA with an AUC of 0.986 in those with joint deformity. In addition, we showed that butyrate promoted T regs , while suppressing T convs and osteoclasts, due to potentiation of the reduction in HDAC expression and down-regulation of proinflammatory cytokine genes. Dietary butyrate supplementation conferred anti-inflammatory benefits in a mouse model by rebalancing T FH cells and T regs , as well as reducing antibody production. These findings reveal the critical role of butyrate-metabolizing species and suggest the potential of butyrate-based therapies for RA patients.

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