Effects of single-anastomosis duodenal-ileal bypass with sleeve gastrectomy on gut microbiota and glucose metabolism in rats with type 2 diabetes

Abstract

Background: Bariatric and metabolic surgery often leads to significant changes in gut microbiota composition, indicating that changes in gut microbiota after bariatric and metabolic surgery might play a role in ameliorating type 2 diabetes (T2D). However, the effects of single-anastomosis duodenal-ileal bypass with sleeve gastrectomy (SADI-S) on gut microbiota in T2D remain unclear.

Objectives: To investigate the effects of SADI-S on gut microbiota and glucose metabolism in T2D rats.

Methods: Nineteen T2D rats were randomly divided into the SADI-S group (n = 10) and the sham operation with pair-feeding group (sham-PF, n = 9). Fecal samples were collected to analyze the gut microbiota composition with 16S ribosomal DNA gene sequencing. The fasting blood glucose and glycated hemoglobin were measured to evaluate the effects of SADI-S on glucose metabolism.

Results: The Chao and ACE index results indicated the richness of the gut microbial community. The ACE and Chao index values were significantly lower in the SADI-S group than in the sham-PF group, indicating that indicating that species richness was significantly lower in the SADI-S group than in the sham-PF group (p < 0.05). Shannon and Simpson indices were used to estimate the species diversity of the gut microbiota. Compared with the sham-PF group, the SADI-S group showed significantly lower Shannon index and higher Simpson index values, indicating that the species diversity was significantly lower in the SADI-S group than in the sham-PF group (p < 0.05). At the genus level, SADI-S significantly changed the abundances of 33 bacteria, including the increased anti-inflammatory bacteria (Akkermansia and Bifidobacterium) and decreased pro-inflammatory bacteria (Bacteroides). SADI-S significantly decreased the fasting blood glucose and glycated hemoglobin levels. The blood glucose level of rats was positively correlated with the relative abundances of 12 bacteria, including Bacteroides, and negatively correlated with the relative abundances of seven bacteria, including Bifidobacterium.

Conclusion: SADI-S significantly altered the gut microbiota composition of T2D rats, including the increased anti-inflammatory bacteria (Akkermansia and Bifidobacterium) and decreased pro-inflammatory bacteria (Bacteroides). The blood glucose level of rats was positively correlated with the abundances of 12 bacteria, including Bacteroides, but negatively correlated with the relative abundance of 7 bacteria, including Bifidobacterium. These alternations in gut microbiota may be the mechanism through which SADI-S improved T2D. More studies should be performed in the future to validate these effects.

Keywords: SADI-S; T2D; bariatric and metabolic surgery; gut microbiota; single-anastomosis duodenal–ileal bypass with sleeve gastrectomy; type 2 diabetes.

FIGURE 1

Changes in the body weight (A), fasting blood glucose level (B), glycated hemoglobin level (C), and area under the curve of the glucose level in the intraperitoneal glucose tolerance test (IPGTT) (F) preoperatively and postoperatively. Changes in the blood glucose level in IPGTT at each time point preoperatively (D) and 8 weeks postoperatively (E). *Significant difference (p < 0.05); NS, no significance (p > 0.05). HBA1c, glycated hemoglobin; AUC, area under the curve; IPGTT, intraperitoneal glucose tolerance test.

FIGURE 2

Double-labeling immunofluorescence images. Morphological and histological evaluations of pancreatic tissues in the two groups. The red color represents the pancreatic islet α-cells. The green color represents the pancreatic islet β-cells. The blue color represents the cell nucleus.

FIGURE 3

Evaluations of the rarefaction curve (A), species accumulation curve (B), rank–abundance curve (C), and principal component (D) in the two groups 8 weeks postoperatively.

FIGURE 4

Comparison of the α-diversity of the gut microbiota. Changes in the ACE (A), Chao (B), Shannon (C), and Simpson (D) indices in the two groups 8 weeks postoperatively.

FIGURE 5

Changes in the taxonomic composition of the gut microbiota at the phylum level.

FIGURE 6

Relationship between the differential genera and metabolic variables. *p < 0.05; **p < 0.01. FBG, fasting blood glucose; AUC, area under the curve of the blood glucose level in intraperitoneal glucose tolerance test; HBA1c, glycated hemoglobin.