(P30-002-23) Fiber Fermentation and Tolerance in UC Patients: Role of Gut Bacterial Dysbiosis

Objectives: Ulcerative Colitis (UC) is characterized by gut inflammation, altered barrier function and gut bacterial dysbiosis. Dietary fiber has been shown to improve gut barrier function and reduce inflammation, but UC patients are recommended to avoid consuming fiber-rich foods because of their intolerance to certain fibers. The objective of this research is to determine the efficacy and tolerance of pectin (HMP) in UC using mice colonized with UC-associated bacteria.

Methods: Six-week-old IL-10 KO germ-free mice were randomly assigned to a purified control diet or a 15% HMP diet. Mice were colonized via oral gavage using fecal microbiota from a fiber-intolerant individual and UC patient. Intestinal permeability was evaluated by FITC-D in vivo. RT-qPCR is currently being used to measure the relative gene expression of inflammatory cytokines. Gas production, short-chain fatty acids (SCFAs) and pH were measured at regular intervals during in vitro fermentation. Gas production was measured by syringe displacement and SCFAs were quantified using GC-FID.

Results: In in vitro fermentation, UC-associated bacteria did not differ significantly from non-UC-associated bacteria in HMP fermentation and SCFA production after 12 hours. After 24 hours, the dysbiotic bacteria did not increase SCFA production. Mice colonized with colitis-associated bacteria had increased permeability, spleen and liver weights and reduced colon lengths, which are common in UC. HMP supplementation increased gut permeability and did not show any amelioration in increased spleen and liver weights indicating intolerance. But HMP ameliorated UC-induced shortening of colons. Despite HMP’s capacity to produce SCFAs in-vitro, gut barrier function in the in-vivo UC model was not improved. We are currently measuring inflammatory parameters to determine the effect of HMP in attenuating UC.

Conclusions: HMP assimilation in the gut was influenced by bacterial dysbiosis and did not show any ameliorating effects on gut barrier function. A longer-term consumption or a higher concentration of HMP may be needed to exert beneficial effects against colitis.

Funding Sources: Whistler Center for Carbohydrate Research and Ralph W. and Grace M. Showalter Research Trust Award