Irritable bowel syndrome (IBS) is a digestive condition that affects around 10% of the population, and is often characterised by abdominal pain or discomfort, including symptoms such as: stomach cramps, bloating, diarrhoea and constipation, all of which can be painful and impact on the sufferers quality of life.^1,2 Although the aetiology and pathophysiology of IBS is yet to be fully understood it is known to be multifactorial², with the gut microbiota being an influential factor. Studies have shown that there are differences in the faecal microbiota of patients with IBS compared to healthy controls.^3,4  Therefore, correcting the microbial dysbiosis that has been associated with IBS, is an area of research that is gaining popularity.  

Faecal microbiota transplantation (FMT), the administration of a stool solution, containing commensal bacteria, from a donor into the intestinal tract of a recipient to alter the gut microbiota^5,6,  has previously been shown to treat recurring Clostridioides difficile infections⁷, another condition associated with microbial dysbiosis⁸. Therefore Lahtinen and colleagues investigated whether FMT could be effective in the treatment of IBS.⁹

This recent study found that FMT, besides altering the microbial composition of the treated patients and reducing their stool water content, only has a transient effect on reducing IBS symptoms; according to the IBS Symptom Severity Score (IBS-SSS) questionnaire. 

In this randomised, placebo-controlled trial, 49 subjects with IBS [subtypes: IBS-D n=25, IBS-mixed n=7, unsubtyped n=14, remission n=3] were given an FMT. All participants received one single colonoscopy; the autologous group (n=26), also known as the placebo group, received their own faecal suspension, and the allogenic (n=23), or treatment group, received a faecal suspension from a single universal donor (a young healthy male). The effects of this single colonoscopy on IBS symptoms, mental wellbeing, quality of life and microbial composition were monitored at several timepoints in the year following the FMT.  

The endpoint of this study was a 50-point reduction in IBS-SSS that was maintained for 52 weeks; this was not found for either the treatment  or placebo FMT groups. Nevertheless, a significant reduction of the IBS-SSS after 3m of the colonoscopy was found in the treatment FMT group (P =0.01) where the score reduced from 270 to 189. There was no marked reduction in mean IBS-SSS at any timepoint in the placebo FMT group. The authors hypothesised that the transient relief of IBS symptoms may be due to the functionality and metabolism of the microbiota not being preserved in the new host. 

Although overall there was no difference in the total depression or anxiety scores compared to baseline or between groups, interestingly, in the ‘responders’, ie. those who had a  reduction in IBS-SSS of 50 points or more at any recorded time point as compared to baseline, of the treatment FMT group, they also had a reduction in depression score (P=0.05). This effect was not found in the placebo FMT group, even in those who had an overall improvement in IBS-SSS. 

When the faecal samples of participants were analysed, those who received the treatment FMT were found to have a microbial composition similar to that of the donor and had a significant decrease in stool water content at weeks 26 (P = 0.005) and 52 (P=0.001), when compared to baseline. 

Overall, these findings show that a single donor FMT can only provide short term relief from IBS symptoms and further studies looking into repeated treatments or finding a ‘super donor’, and a better understanding of the mechanisms, are required before this could be considered as a recommendation in the treatment of IBS.  

 

References

1. National Institute for Health and Care Excellence (2008) Irritable bowel syndrome in adults: diagnosis and management [online]. Updated April 2017. [Accessed 12th May 2020]. Available from: https://www.nice.org.uk/guidance/cg61/chapter/Introduction

2. Enck et al. (2016) Nature Reviews Disease Primers 2:16014

3. Codling et al. (2010) Digestive Diseases and Sciences 55(2):392-397 

4. Durbán et al. (2012) Environmental Microbiology Reports 4(2):242-247

5. National Health Service (2014) Faecal microbiota (stool) transplantation (FMT) [online]. [Accessed 12th June 2020]. Available from : https://www.guysandstthomas.nhs.uk/resources/patient-information/infection/fmt.pdf

6. Gupta et al. (2016) Therapeutic Advances in Gastroenterology 9(2):229-239

7. Quraishi et al. (2017) Alimentary Pharmacology and Therapeutics 46(5):479-493

8. Antharam et al. (2013) Journal of Clinical Microbiology 51(9):2884-2892 

9. Lahtinen et al. (2020) Alimentary Pharmacology and Therapeutics. doi: 10.1111/apt.15740. [Epub ahead of print]

 

25/06/2020