Impact of Sleeve Gastrectomy on Fecal Microbiota in Individuals with Morbid Obesity

Abstract

Background: The intestinal microbiota plays an important role in the etiology of obesity. Sleeve gastrectomy (SG) is a frequently performed and effective therapy for morbid obesity.

Objective: To investigate the effect of sleeve gastrectomy on the fecal microbiota of individuals with morbid obesity and to examine whether shifts in microbiota composition are associated with markers of inflammation and intestinal barrier function.

Methods: Fecal and blood samples of healthy individuals (n = 27) and morbidly obese individuals pre-SG (n = 24), and at 2 months (n = 13) and 6 months post-SG (n = 9) were collected. The 16SrRNA gene was sequenced to assess microbiota composition. Fecal calprotectin, plasma inflammatory markers and intestinal permeability markers (multi-sugar test) were determined.

Results: Fecal microbiota composition between morbidly obese and lean individuals was significantly different. The fecal microbiota composition changed significantly 2 and 6 months post-SG (p = 0.008) compared to pre-SG but not towards a more lean profile. The post-SG microbiota profile was characterized by an increase in facultative anaerobic bacteria, characteristic for the upper gastrointestinal tract. No correlations were found between inflammatory markers, intestinal permeability and microbial profile changes.

Conclusions: Fecal microbiota composition in morbidly obese individuals changed significantly following SG. This change might be explained by functional changes induced by the SG procedure.

Keywords: gut microbiota in obesity; intestinal permeability; sleeve gastrectomy.

Figure 1

Flowchart of study design.

Figure 2

Alpha diversity indices (observed species (a), Chao1 (b), Shannon diversity index (c) and PD whole tree (d)) of healthy individuals (HC) and patients with obesity pre (T1), two (T2) and six months (T3) post-SG. Data are presented as boxplots displaying medians with interquartile ranges. * indicates p < 0.05.

Figure 3

Visual representation of the microbiota composition in healthy, lean individuals (A) and patients pre-SG (B), two (C) and six months (D) post-SG. The microbiota is presented from the domain to the species level.

Figure 3

Visual representation of the microbiota composition in healthy, lean individuals (A) and patients pre-SG (B), two (C) and six months (D) post-SG. The microbiota is presented from the domain to the species level.

Figure 3

Visual representation of the microbiota composition in healthy, lean individuals (A) and patients pre-SG (B), two (C) and six months (D) post-SG. The microbiota is presented from the domain to the species level.

Figure 4

PCA based on the fecal microbiota composition of healthy individuals (red circle), individuals with obesity pre (T1; blue squares), two (T2; green diamonds) and six months (T3; orange crosses) post-SG. The ellipses are 2D-normal-based ellipses at the 66% confidence level. Horizontal axis: “PCA1”, vertical axis: “PCA2”.

Figure 5

RDA based on the fecal microbiota composition of healthy individuals (circles) and patients pre-GS (squares). The 20 taxa that contributed most to the separation are represented by arrows. The effect of the variable BMI is represented by the red arrow. Horizontal axis: “RDA1”, vertical axis:”PRCA1”.

Figure 6

RDA based on the fecal microbiota composition of individuals pre-GS (squares), and two (diamonds) and six months (crosses) post-GS (A); RDA based on the fecal microbiota composition of individuals pre-GS (squares) and two months post-SG (diamonds) (B); and RDA based on the fecal microbiota composition of individuals pre-SG (squares) and six months post-SG (crosses) (C). The 20 bacterial taxa that contributed most to the separation are represented by arrows. The ellipses are 2D-normal-based ellipses at the 66% confidence level.