Both Gut Microbiota and Differentially Expressed Proteins Are Relevant to the Development of Obesity.

Although the role of the gut microbiota in obesity has recently received considerable attention, the exact mechanism is unclear. This study was aimed at investigating the profiles of bacterial communities in fecal samples and differentially expressed proteins (DEPs) in the peripheral blood in mice fed a high-fat diet (HFD) and standard diet (SD) and at providing new insights into the pathogenesis of obesity. The profiles of bacterial communities in fecal samples and DEPs in the peripheral blood were characterized in mice fed HFD and SD, respectively. The levels of 3 DEPs increased in HFD mice. The alpha diversity was significantly lower after 4 and 12 weeks in HFD mice. The beta diversity was higher after 4, 8, and 12 weeks in HFD mice. A total of 16 gut bacterial clades were significantly different with the linear discriminant analysis (LDA) score higher than 4 over time. The relative abundance levels of Proteobacteria and Deferribacteres were higher, while those of Bacteroidetes and Firmicutes were lower in HFD mice at the phylum level. The relative abundance of Desulfovibrionaceae and Rikenellaceae increased in HFD mice at the family level. The relative abundance of the Bacteroidetes_S24-7_group and Lachnospiraceae was lower in HFD mice. The gut microbiota had a significant correlation with serum lipid indexes and expression of DEPs at the phylum and family levels. The changes in the gut microbiota of HFD mice and their associations with the levels of inflammatory proteins could be one of the major etiological mechanisms underlying obesity.