Alterations in gut microbiota during remission and recurrence of diabetes after duodenal-jejunal bypass in rats

Abstract

Aim: To observe the alterations in gut microbiota in high-fat diet (HFD)-induced diabetes recurrence after duodenal-jejunal bypass (DJB) in rats.

Methods: We assigned HDF- and low-dose streptozotocin-induced diabetic rats into two major groups to receive DJB and sham operation respectively. When the DJB was completed, we used HFD to induce diabetes recurrence. Then, we grouped the DJB-operated rats by blood glucose level into the DJB-remission (DJB-RM) group and the DJB-recurrence (DJB-RC) group. At a sequence of time points after operations, we compared calorie content in the food intake (calorie intake), oral glucose tolerance test, homeostasis model assessment of insulin resistance (HOMA-IR), concentrations of glucagon-like peptide 1 (GLP-1), serum insulin, total bile acids (TBAs) and lipopolysaccharide (LPS) and alterations in colonic microbiota.

Results: The relative abundance of Firmicutes in the control (58.06% ± 11.12%; P < 0.05 vs sham; P < 0.05 vs DJB-RC) and DJB-RM (55.58% ± 6.16%; P < 0.05 vs sham; P < 0.05 vs DJB-RC) groups was higher than that in the sham (29.04% ± 1.36%) and DJB-RC (27.44% ± 2.17%) groups; but the relative abundance of Bacteroidetes was lower (control group: 33.46% ± 10.52%, P < 0.05 vs sham 46.88% ± 2.34%, P < 0.05 vs DJB-RC 47.41% ± 5.67%. DJB-RM group: 34.63% ± 3.37%, P < 0.05 vs sham; P < 0.05 vs DJB-RC). Escherichia coli was higher in the sham (15.72% ± 1.67%, P < 0.05 vs control, P < 0.05 vs DJB-RM) and DJB-RC (16.42% ± 3.00%; P < 0.05 vs control; P < 0.05 vs DJB-RM) groups than in the control (3.58% ± 3.67%) and DJB-RM (4.15% ± 2.76%) groups. Improved HOMA-IR (2.82 ± 0.73, P < 0.05 vs DJB-RC 4.23 ± 0.72), increased TBAs (27803.17 ± 4673.42 ng/mL; P < 0.05 vs DJB-RC 18744.00 ± 3047.26 ng/mL) and decreased LPS (0.12 ± 0.04 ng/mL, P < 0.05 vs DJB-RC 0.19 ± 0.03 ng/mL) were observed the in DJB-RM group; however, these improvements were reversed in the DJB-RC group, with the exception of GLP-1 (DJB-RM vs DJB-RC P > 0.05).

Conclusion: Alterations in gut microbiota may be responsible for the diabetes remission and recurrence after DJB, possibly by influencing serum LPS and TBAs.

Keywords: Diabetes recurrence; Duodenal-jejunal bypass; Gut microbiota; Lipopolysaccharide; Total bile acids.

Figure 1

Body weight and calorie content in the food intake (calorie intake). Shown are body weight (A) and calorie intake (B) of rats at baseline, 4, 8 and 12 wk after surgery. ^aP < 0.05 vs control group.

Figure 2

Serum insulin after oral glucose administration. Shown are levels of serum insulin after oral glucose gavage (1 g/kg) at 4 wk (A) and 12 wk (B) after surgery, between which there are no significant differences with the use of mixed model one-way analysis of variance followed by Bonferroni post hoc comparisons. Area under the curves for oral glucose tolerance test and homeostasis model assessment of insulin resistance are demonstrated in C and D respectively. ^aP < 0.05 vs control group; ^cP < 0.05 vs sham group; ^eP < 0.05 vs DJB-RC group. DJB-RC: Duodenal-jejunal bypass recurrence group; DJB-RM: Duodenal-jejunal bypass-remission group.

Figure 3

Level of glucagon-like peptide 1 after administration of oral glucose. Shown are glucagon-like peptide 1 (GLP-1) level after oral glucose gavage (1 g/kg) at 4 wk (panel A) and 12 wk (panel B) after surgery. In terms of global GLP-1 concentration, the illustrations in the rectangles show that there are significant differences between the groups with the use of mixed model one-way analysis of variance followed by Bonferroni post hoc comparisons. DJB-RC: Duodenal-jejunal bypass recurrence group; DJB-RM: Duodenal-jejunal bypass-remission group.

Figure 4

Fasting serum total bile acids and lipopolysaccharide. Fasting serum TBAs (A) and LPS (B) were measured at 4 and 12 wk after surgery. ^aP < 0.05 vs control group; ^cP < 0.05 vs sham group; ^eP < 0.05 vs DJB-RC group. DJB-RC: Duodenal-jejunal bypass recurrence group; DJB-RM: Duodenal-jejunal bypass-remission group; TBAs: total bile acids; LPS: Lipopolysaccharide.

Figure 5

Principal component analysis and heatmap analysis. A: Principal component analysis was used to construct a 2-D graph to summarize the factors mainly responsible for this difference. Similarity was high when two samples were closely located. A number in brackets represents contributions of principal components to differences among samples; B: Heat map analysis: The longitudinal clustering indicates the similarity of all species among different samples, and horizontal clustering indicates the similarity of certain species among different samples, the closer the distance and the shorter the branch length, the more similar the species composition is between the samples.

Figure 6

Species annotation. Species annotation (A) is the taxonomic composition distribution histogram of each sample at the phylum level. The ratios of each phylum in certain samples are displayed. The relative abundance of Bacteroidetes (B), Firmicutes (C), Proteobacteria (D) and Escherichia coli (E) between the groups was analyzed by the Wilcoxon test. ^aP < 0.05 vs control group; ^cP < 0.05 vs sham group; ^eP < 0.05 vs DJB-RC group. DJB-RC: Duodenal-jejunal bypass recurrence group; DJB-RM: Duodenal-jejunal bypass-remission group.