Figures & data
Figure 1. Clinical effects of small bowel resection. (A) The weight of piglets that received a small bowel resection (SBR) was significantly lower two weeks post-surgery than those that received a sham surgery (Sham) or no surgery (NOC; **p < 0.01). This suboptimal weight gain was sustained for the duration of the experiment (***p < 0.001 at week 3, p < 0.0001 at weeks 4, 5 and 6). The sham piglets also had a significantly lower weight gain at weeks 5 (#p < 0.05) and 6 (###p < 0.0001) compared with the NOC group. Values are expressed as mean ± SEM; n = 12 NOC, n = 10 sham, n = 12 SBR at pre-op, week 1 and week 2; n = 6 NOC, n = 5 sham, n = 6 SBR at weeks 3, 4, 5 and 6. (B) Piglets in the SBR group had a significantly higher stool consistency score than the sham and NOC groups two weeks (**p < 0.01) and six weeks (***p < 0.001) post-surgery. Values are expressed as mean ± SEM; n = 5−6/group/time-point.
Table 1. Surgical resection decreases the diversity of colonic bacteria. Estimation of diversity within the non-operation control (NOC), sham and small bowel resection (SBR) groups at two- and six- weeks post surgery as assessed by Chao 1 richness estimation, Shannon’s index for diversity, number of observed species and Simpson’s diversity index
Figure 2. Surgical resection of the small intestine decreases the diversity of colonic bacteria and alters the relative proportion of families in the Firmicutes phylum. (A) There is a decrease in the number of distinct operational taxonomic units (OTUs) representing bacterial genera two and six weeks post-surgery in the small bowel resection (SBR) group compared with the non-operation control (NOC) and sham group. This is translated into a decrease in overall bacterial diversity as calculated by the Chao 1 richness estimation (B). (C) Pie charts representing the major bacterial phyla and the relative proportion of families in the Firmicutes family at the two- and six-week time-point in the NOC, sham and SBR groups.
Table 2. Small bowel resection alters the composition of the colonic microbiota over time. The composition of the colonic microbiota is altered two and six weeks post-surgery in the small bowel resection (SBR) group. Values are relative proportions of operational taxonomic units (OTUs) ± SEM, n = 5−6/group/time-point. Statistical significance was determined using a general linear model ANOVA; *p < 0.05; **p < 0.01; ***p < 0.001 compared with non-operation control (NOC) group; †p < 0.05, ††p < 0.01, †††p < 0.001 compared with sham group
Figure 3. Surgical resection alters the expression of pro-inflammatory cytokines in the colon. In the colon, the gene expression of IL-1β (A), IL-18 (C) and TNF-α (D) was significantly higher in the SBR group compared with the sham group at six weeks (*p < 0.05, **p < 0.01). IL8 (B) was significantly higher in the colon in the small bowel resection (SBR) group compared with the non-operation control (NOC) and sham group at six weeks (*p < 0.05). Values are expressed as mean ± SEM; n = 5−6/group/time-point.
Table 3. A decrease in colonic bacterial diversity is associated with an increase in inflammatory cytokines. The expression of colonic IL-1β and IL-8 negatively correlate with colonic bacterial diversity as assessed by Spearman’s rank correlation coefficient
Figure 4. There is an increase in inflammatory cells and mediators in the colonic epithelium following small bowel resection. There was an increase in the number of macrophages (A) and the percentage of cytoplasmic inducible nitric oxide synthase (iNOS) staining (B) in the colonic epithelium six weeks post-surgery. Immunohistochemistry images illustrate representative staining six weeks post-surgery. Scale bar represents 100 µm. Values are expressed as mean ± SEM; n = 5−6/group.
