Experimental Models of Partial Intestinal Obstruction in Young Mice: Establishment, and Evaluation

Alterations of gut microbiota in a mouse model with partial small intestinal obstruction

Introduction

Changes in the gut microbiota of patients with partial small intestinal obstruction (PSIO) have not been widely clarified. We aimed to explore bacterial diversity in a PSIO mouse model.

Methods

A PSIO mouse model was established using male C57BL/6 mice, and feces samples from the distal ileum and ileum epithelium tissues were collected. MiSeq sequencing of the 16S rRNA gene was conducted to characterize microbiota diversity and composition. RNA sequencing for differences in transcriptomic programming of the ileum tissue was performed between the PSIO and (Control) Ctrl groups.

Results

Bacterial diversity in the PSIO group was significantly lower than that in the controls. Pseudomonadota was predominant in the feces of the PSIO group. Unclassified_Muribaculaceae (p = 0.008) and Akkermansia (p = 0.007) were more abundant in the Ctrl group than those in the PSIO group. Furthermore, Escherichia_Shigella (p = 0.008) was more predominant in the feces of the PSIO group. The Kyoto Encyclopedia of Genes and Genomes pathways related to metabolism were depleted in the PSIO group. Pathways associated with intestinal fibrosis, including extracellular matrix-receptor interaction, focal adhesion, phosphoinositide 3-kinase (PI3K)-Akt signaling pathway and transforming growth factor (TGF)-beta signaling pathway, which were enriched in ileum epithelial tissue in the PSIO group.

Conclusion

PSIO can lead to changes in the predominant intestinal bacterial groups. Depleted functional profiles of the gut microbiota were identified in the PSIO group. Functional pathways associated with intestinal fibrosis were activated by PSIO. The potential regulation by the microbiota needs to be explored in the future.

Experimental Intestinal Stenosis Alters Crohn's Disease-Like Intestinal Inflammation in Ileitis-Prone Mice

BACKGROUND

Clinical observations indicate that mechanical factors contribute to the expression or recurrence of Crohn's disease. We investigated whether the creation of an intestinal stenosis could alter the severity of the expected Crohn-like ileitis, in a Crohn's disease animal model, the TNF^Δare/+ mouse.

METHODS

Thirty-six, 6-weeks-old TNF^Δare/+ mice, were divided into 3 intervention groups: triple suture, single suture and sham. In the terminal ileum, in the first group, a triple suture stenosis was created, whereas, in the second, a loose suture was placed. Same triple-suture stenosis was performed on twelve wild type mice. All animals were sacrificed at 6 weeks post-operatively and the ileum parts were evaluated histopathologically. A summative total ileitis score was applied in each sample using a bespoke semiquantitative histological scoring system for the Crohn-like changes.

RESULTS

The triple suture stenosis induced significant muscular hypertrophy proximal to interventional site which was more prominent in TNF^Δare/+ than wild type mice. In triple suture group, the total ileitis score was significantly increased proximal to the intervention as compared to the single suture (P: 0.004) and the sham groups (P: 0.013). The total ileitis score distally, was unaffected, regardless of the experimental intervention. Intestinal stenosis did not induce intestinal inflammation in wild type mice.

CONCLUSION

The creation of a stenosis in the terminal ileum of TNF^Δare/+ mice alters Crohn-like inflammation. We assume that mechanical forces, such as intraluminal pressure, may contribute as important co-factors to the pathophysiology of Crohn's disease in genetically predisposed subjects.