Alteration of gut microbiota affects expression of adiponectin and resistin through modifying DNA methylation in high-fat diet-induced obese mice

Abstract

Background: Adiponectin and resistin are typically secreted by the adipose tissue and are abnormally expressed in obesity. However, the underlying influential factors and mechanisms are to be elucidated. It is well known that the expression of genes is regulated by epigenetics while gut microbiota participates in epigenetic processes through its metabolites such as folate, biotin, and short-chain fatty acids (SCFAs). Therefore, we supposed that alteration of gut microbiota might affect the transcriptional expression of adiponectin and resistin through epigenetic regulation in obesity.

Methods: C57BL/6J mice were fed either a high-fat diet (34.9% fat by wt., 60% kcal) or a normal-fat diet (4.3% fat by wt., 10% kcal) for 16 weeks, with ampicillin and neomycin delivered via drinking water to interfere with gut microbiota development. Fecal microbiota was analyzed by 16S rRNA high-throughput sequencing. The mRNA expression levels of genes were measured by real-time quantitative RT-PCR. SCFA contents in feces were examined using gas chromatography.

Results: Alteration of the gut microbiota induced by antibiotic use, characterized by a dramatic reduction of the phylum Firmicutes and Actinobacteria and an increase of Proteobacteria with reductions of genera including Lactobacillus, norank_f_Bacteroidales_S24-7_group, Alistipes, Desulfovibrio, Helicobacter, etc., and increases in Bacteroides, Enterobacter, Klebsiella, inhibited the body weight gain in mice fed the high-fat diet instead of the normal-fat diet. The mRNA expression of adiponectin and resistin was upregulated by antibiotic use in mice fed the high-fat diet, accompanied by increased expression of fat oxidation and thermogenesis-related genes (PPAR-α, Pgc-1α, and Atgl) in the fat and/or liver, whereas no change in the expression of adiponectin and resistin was found in mice fed the normal-fat diet. Furthermore, antibiotic use reduced DNA methylation fractions of the adiponectin and resistin promoters and downregulated the expression of DNA methyltransferase 1 and 3a (DNMT1 and DNMT3a) with the high-fat diet feeding.

Conclusion: Alteration of gut microbiota induced by antibiotic use may affect the expression of adiponectin and resistin in mice fed the high-fat diet by modifying promoter DNA methylation, thus leading to increased fatty acid oxidation and less body weight gain.

Keywords: Adipokines; Antibiotics; DNA methylation; Gut microbiota; Obesity.

Fig. 1

Effects of antibiotics on body weight gain in the high-fat diet-fed mice. Three to 4-week-old C57BL/6J male mice were fed a high-fat diet to induce obesity (DIO group) for 16 weeks, with a normal-fat diet as control (NC group). Meanwhile, ampicillin (1 g/L) and neomycin (0.5 g/L) were delivered via drinking water to mice fed the high-fat diet (DIO-AB group) and the normal-fat diet (NC-AB group). Antibiotic use lessened the weight gain (a, b) with no changes in energy intake (c), and reduced adipocyte size (d, e). n = 10 in each group. Data are means ± SD. *Compared to the NC group, P < 0.05; ^#compared to the DIO group, P < 0.05

Fig. 2

Effects of antibiotics on gut microbiota compositions. The mouse experimental procedure was the same as in Fig. 1. a–e Community bar-plot analysis on the fecal microbiota compositions at the levels ranged from the phylum, class, order, and family to genus. f, g Bacterial communities at the phylum and genus levels based on weighted UniFrac distance using the NMDS analysis. n = 10 in each group

Fig. 3

Changes in fecal short-chain fatty acids with antibiotic use and their correlation with the mRNA expression of adipokines. The mouse experimental procedure was the same as in Fig. 1. a Contents of acetate, propionate, and butyrate in the feces. b Expression of adipose adiponectin and resistin. c Correlation between adiponectin and SCFAs. d Correlation between resistin and SCFAs. n = 5–6 in each group. Data are means ± SD. *Compared to the NC group, P < 0.05; ^#compared to the DIO group, P < 0.05

Fig. 4

Effects of antibiotics on the mRNA expression of genes associated with fatty acid metabolism and DNA methyltransferase in the adipose tissue. The mouse experimental procedure was the same as in Fig. 1. a, b Fat synthesis-associated genes, acetyl-CoA carboxylase 1 (Acc1), and fatty acid synthase (Fas). c–f Fat hydrolysis and oxidation-associated genes, cell death-inducing DNA fragmentation factor-alpha-like effector A (Cidea), adipose triglyceride lipase (Atgl), peroxisome proliferator-activated receptor-alpha (PPAR-α), peroxisome proliferator-activated receptor-γ coactivator1 alpha (Pgc-1α). g–i DNA methyltransferases 1, 3a, and 3b (DNMT1, DNMT3a, and DNMT3b). n = 10 in each group. Data are means ± SD. *Compared to the NC group, P < 0.05; ^#compared to the DIO group, P < 0.05

Fig. 5

Effects of antibiotics on the mRNA expression of genes associated with fatty acid metabolism in the liver. The mouse experimental procedure was the same as in Fig. 1. a, b Fat synthesis-associated genes, acetyl-CoA carboxylase 1 (Acc1), and fatty acid synthase (Fas). c–f Fat hydrolysis and oxidation-associated genes, cell death-inducing DNA fragmentation factor-alpha-like effector A (Cidea), adipose triglyceride lipase (Atgl), peroxisome proliferator-activated receptor-alpha (PPAR-α), peroxisome proliferator-activated receptor-γ coactivator1 alpha (Pgc-1α). n = 10 in each group. Data are means ± SD. *Compared to the NC group, P < 0.05; ^#compared to the DIO group, P < 0.05