Synbiotics and Post-op Crohn's Disease

Crohn's disease (CD) is characterized by chronic intestinal inflammation and commonly involves the ileocecal region. Due to disease complications, many patients with CD require an ileocecal resection (ICR). However, disease often recurs postoperatively at the surgical anastomosis, with endoscopic recurrence rates as high as 85%. While the immunosuppressant infliximab has been shown to reduce endoscopic disease recurrence, it was not shown to prevent clinical relapse. The timing of infliximab treatment might be critical, as starting infliximab immediately after surgery rather than at the time of post-surgical recurrence resulted in 1-year remission rates of 92% and 57%, respectively. Currently, no ideal postoperative care exists for patients with CD. Thus, new approaches are required.

The gut microbiome has long been thought to play a causative role in the high rates of CD recurrence following surgical resection. Immediately following ICR, a state of inflammation and oxidative stress promotes aerotolerant microbes at the expense of beneficial short-chain fatty acid (SCFA)-producing anaerobes. The mucosal microbial composition in CD patients at the time of surgery is predictive of future disease relapse. Specifically, patients with a dominance of SCFA-producing anaerobic bacteria in the ileal mucosa at the time of surgical resection are more likely to remain in remission compared with patients which have a dominance of aerotolerant bacteria. Nutritional adjuncts based on probiotics or prebiotics could be applied to shift gut microbial imbalances towards SCFA-producers.

Though research is limited, probiotics containing bifidobacteria but not lactobacilli have been shown to lessen mucosal inflammation and recurrence rates when provided immediately post ICR. In a previous clinical trial, it was found that patients with CD that started the probiotic VSL#3 (4 Lactobacillus; 3 Bifidobacterium; 1 Streptococcus strains) immediately post surgery had reduced mucosal inflammatory cytokines and lower recurrence rates when compared to patients that started VSL#3 at 3-months post surgery. A smaller trial using VSL#3 in combination with antibiotic treatment also showed lower rates of endoscopic recurrence at 3- and 12-months following surgery. These results suggest that probiotic composition and treatment timing are critical for efficacy. While synergy between probiotics and prebiotics might improve clinical effects, the efficacy of synergistic synbiotics remains unknown. The aims of this study are the following:

AIM 1. Perform a parallel two-arm, randomized controlled exploratory trial in CD patients undergoing ICR to determine the safety and tolerability of a synbiotic treatment.

This is a pilot study in patients with CD undergoing ileocecal resection to evaluate the feasibility of supplementation with a synbiotic preparation that contains a mixture of resistant starch type 2 (HiMaize 260; Ingredion), arabinoxylan (Naxus; Bioactive), and galactooligosaccharide (Vivinal; FrieslandCampina) (24g/d) fibers plus probiotic bacteria (Bifidobacterium longum spp. longum R0175, Bifidobacterium animalis spp. Lafti B94, Bifidobacterium bifidum R0071; Lallemand Health Solutions) (3x10^9 CFU/d). Participants will be given the probiotics 2 days prior to surgery and then the synbiotic will both be given 7 days after surgery and will be consumed daily for 6 months. Digestible maltodextrin will be used as a placebo control (Maltodextrin GLOBE Plus 15; Ingredion). A total of 36 volunteers will be enrolled, stratified by sex, and randomized to one of 2 groups via computer-generated numbers, as well as blinded to their group allocation to reduce bias. Safety and tolerability of synbiotic (primary outcome) will be determined by the percentage of participants who experience treatment emergent adverse events and serious adverse events. Symptom and quality of life questionnaires will also be used to evaluate tolerance.

AIM 2. Determine if synbiotic therapy attenuates mucosal and systemic inflammation and reduces rates of disease relapse.

Each month, clinical recurrence will be evaluated by Harvey Bradshaw Index and C-reactive protein, serum cytokines (TNF-α, IL-6, IL-8, and IL-10), intestinal barrier markers (LPS, LPS-binding protein, and zonulin), and fecal calprotectin levels will be measured. At 6-months, endoscopic recurrence will be determined by Rutgeerts Index and biopsies will be taken for the assessment of mucosal inflammation.

AIM 3. Evaluate the impact on compositional and functional features of the fecal microbiota and to characterize associations between clinical and microbial outcomes.

Fecal samples will be collected each month for the characterization of the microbiota by 16S rRNA gene sequencing. Fecal concentrations of SCFAs and bile acids will also be determined as functional measures of the gut microbiota. Associations between clinical outcomes and microbiota features will be assessed to identify signatures that predict the synbiotic impact.