P0986 - Small Bowel Resection Alters Mucus Barrier Via Changes in the Gut Microbiota

Purpose: Alterations in the intestinal microbiota negatively impact the clinical outcomes of children with short bowel syndrome (SBS). Emerging evidence shows that the intestinal mucosa, composed of a dense network of O-glycan, is critical to the homeostatic relationship between the microbiome and host. Therefore, we hypothesized that the mucin barrier would be altered following massive intestinal resection.

Methods: Mice underwent small bowel resection (SBR) or sham operation. At harvest, intestine was placed in Carnoy’s fixative, embedded, and stained with Periodic acid-Schiff (PAS). MUC2 immunofluorescent staining was performed and analyzed with confocal microscopy. Simultaneously, bacterial gDNA was extracted from mouse fecal pellets and bacterial 16S rRNA analysis was performed. RT-qPCR was used to measure expression of intestinal Core 3 Synthase (C3GnT), which regulates intestinal mucin O-glycan synthesis. The experiment was repeated and mice were given a probiotic supplement during the post-operative period to determine if mucin integrity would be altered.

Results: MUC2 immunostaining showed an increase in mucin thickness in SBR mice compared to shams (152±10.2 vs. 115±9.5, n=7, p<0.05) (Figure 1A top). Similarly, PAS staining (used to detect glycoproteins and mucins) was higher in SBRs compared to sham operated mice (Figure 1A bottom). Fecal 16S sequencing showed a significant decrease in mucinolytic bacterial families Ruminococcaceae and Bifidobacteriaceae after SBR (n=8-9, p<0.01) (Figure 1B). C3GnT expression was equivalent in both groups (n=4, p=0.30). The increased mucin thickness was mitigated by administration of probiotics following resection.

Conclusion: Intestinal mucin thickness is increased following SBR which may be attributable to reduced mucin degradation. Along these lines, SBR mice had lower abundances of glycan consuming bacteria on 16S analysis and mucin thickness was normalized following the administration of post-operative probiotics. The role of mucin-associated changes after SBR provides meaningful insights into ameliorating complications related to microbial dysbiosis in patients with SBS.