Kedia S, Virmani S, Vuyyuru SK, et al.
Gut 2022;71:2401–13. doi: 10.1136/gutjnl-2022-327811.
Microbiota are known to play a role in the pathogenesis of both Ulcerative Colitis (UC) and Crohn’s Disease (CD). Various lifestyle factors, including rural living, absence of antibiotic exposure and larger family size, have been associated with greater microbial diversity and lower risk for development of IBD [1, 2]. Conversely, dietary patterns and constituent elements of the diet have been linked to dysbiosis and increased risk of IBD [3, 4]. Despite these associations, the causal relationship between microbiota disturbance and IBD pathogenesis/disease flares remains unclear.
Current therapeutic strategies for IBD primarily focus on targeting the dysregulated immune response. However, these approaches have limitations, including a “ceiling effect” of current treatments and a high risk of relapse following withdrawal of therapy . Consequently, there has been a growing interest in exploring alternative interventions, including through modulation of the gut microbiota or manipulation of dietary factors. Most of the evidence for such therapeutic approaches has focused on CD, including with the use of exclusive enteral nutrition . In UC, microbiota modification has been attempted by faecal microbiota transplantation (FMT) in cohort studies and in randomised controlled trials. However, heterogeneous protocols, methods, donors, doses and intervals of FMT have all likely contributed to the conflicting evidence base for FMT in UC. Notably, however, a recent meta-analysis has suggested an overall clinical and endoscopic benefit of FMT, at least in the short term, in the treatment of UC .
Given that dietary intake has the capacity to induce rapid microbial changes, Kedia et al. sought to explore the role of diet combined with FMT in UC, hypothesising that such an approach might enhance the success of FMT by favouring a microbiota composition with increased anti-inflammatory capacity.
The FMT-AID trial (ISRCTN15475780) was an open-label randomised controlled trial conducted to evaluate the effectiveness of FMT combined with an anti-inflammatory diet in adult patients with mild-moderate [Simple Clinical Colitis Activity Index (SCCAI) 3–9], endoscopically active [Ulcerative Colitis Endoscopic Index of Severity (UCEIS) >1] UC on stable therapy. The FMT-AID group, who received seven weekly sessions of FMT (with no antibiotic or bowel preparation prior to FMT), was compared to an optimised standard medical therapy (SMT) group, who continued on their baseline medication with dose optimisation [dose increase of oral 5-aminosalicylic acid (5-ASA) and/or addition of topical 5-ASA or topical steroids]. FMT was performed via colonoscopy using stools obtained from healthy donors residing in rural areas. Patients receiving FMT were also instructed to adhere to an anti-inflammatory diet, which emphasised the avoidance of gluten-based grains, dairy products, processed and red meat, food additives and refined sugars, with an increase in fresh fruits and vegetables and fermented foods.
The primary outcome measures were deep remission [a combination of clinical (SCCAI ≤2) and endoscopic remission (UCEIS ≤1)] and clinical response (SCCAI reduction of ≥3) at week 8. The maintenance phase primary outcome measures were deep remission and steroid-free clinical remission at week 48.
A total of 66 patients (n=35 FMT-AID and n=31 SMT) were included in the analysis. Baseline characteristics, including the baseline dietary macro- and micronutrients, were comparable between groups, except for a lower intake of wheat and insoluble fibre in the FMT-AID group. The trial met its primary outcomes, demonstrating that deep remission at week 8 was significantly higher in the FMT-AID group (36.4% vs 8.7% in the SMT group, p=0.03), as was clinical response at week 8 (65.7% vs 35.5% in the SMT group, p=0.01). Endoscopic response and clinical remission were also superior in the FMT-AID group, although the difference in endoscopic remission did not reach significance. Due to the pandemic, many biomarkers were not available, especially in the SMT group (n=10), for which biomarker outcomes did not show a statistically significant difference. Nonetheless, the number of patients with faecal calprotectin <50 µg/g at week 8 was high in both arms: 85% (17/20) in the FMT-AID group and 60% (6/10) in the SMT group.
Regarding the maintenance phase, 23 FMT-AID and 11 SMT patients entered maintenance. There was a significantly higher rate of deep remission in the FMT-AID group compared to the SMT group (25% vs 0%, p=0.007), while steroid-free clinical remission did not differ significantly. The authors identified mild UC, compared to moderate UC, as a factor associated with higher likelihood of FMT-AID success in inducing remission at week 8. Finally, adverse events were similar in both groups, with no severe adverse events reported.
This is the first FMT trial conducted in Asia, demonstrating impact of microbial modulation in an Indian population. A further novel aspect was the inclusion of an optimised standard medical therapy arm as a comparator instead of placebo, mimicking real-world clinical practice. In addition, stool samples were obtained from rural donors, which is important in the context of recent work demonstrating that healthy individuals in rural areas tend to have a more diverse microbiome than those in urban areas , which may be associated with better outcomes.
The study encountered several difficulties as it was conducted just before the COVID-19 pandemic. Consequently, patient recruitment had to be curtailed: while the initially estimated sample size was 105, only 66 patients were finally enrolled. Additionally, some patients did not have their anticipated seven sessions of FMT or missed follow-up visits – although patients were continued on the anti-inflammatory diet. Missing data for some blood and stool samples at designated time points may have influenced the lack of differences observed in certain comparisons, such as those concerning biochemical outcome measures.
This trial has several implications. First, the approach described offers the benefit of being cost-effective compared to other therapies currently licensed for UC, which is particularly important for IBD clinicians in resource-limited areas. Furthermore, it emphasises the importance of diet in maintaining remission, an area that warrants further exploration.
FMT from rural donors in combination with an anti-inflammatory diet was more effective than optimisation of standard medical therapy in inducing clinical and deep remission in patients with mild to moderate UC. Moreover, deep remission was consistently higher in the FMT-AID arm at 48 weeks, suggesting that the anti-inflammatory diet plays a significant role in this particular context.
Beatriz Gros - Short Biography
Beatriz Gros works as a Senior Clinical Fellow at the Western General Hospital in Edinburgh (United Kingdom) and as a Consultant Gastroenterologist in Reina Sofía University Hospital in Cordoba (Spain). Beatriz has a specific interest in environmental factors associated with development of IBD and predictors for disease flares and has been working with Professor Charlie Lees to better understand these factors in the PREdiCCt study. She is also involved in medical #SoMe (social media) education on both Instagram and Twitter and is the owner and content creator of the educational website www.ibd-eii.com.