Fifty-point IBS-SSS responders but persistence of moderate severity IBS in over 40% of those on diet

I read with great interest the report from Carbone et al1 of the pragmatic open DOMINO trial of low FODMAP diet (in addition to traditional dietary advice) compared with the spasmolytic otilonium bromide in primary care patients with irritable bowel syndrome (IBS). The authors have achieved an important goal in the conduct of such a pragmatic clinical trial in the very relevant primary care setting and with such balanced groups participating in the two arms of the study. The significant difference between the two treatment groups based on the 50-point change in the 500-point IBS-SSS scale is noted. However, in addition to the limitations intrinsic to such an open-label, pragmatic trial identified in the letter by Rej et al,2 it is important to address the clinical significance of the endpoint used to appraise efficacy of treatments in this and other trials using the definition of…

Leggi
Maggio 2023

Identification of bacterial lipopeptides as key players in IBS

Objectives
Clinical studies revealed that early-life adverse events contribute to the development of IBS in adulthood. The aim of our study was to investigate the relationship between prenatal stress (PS), gut microbiota and visceral hypersensitivity with a focus on bacterial lipopeptides containing -aminobutyric acid (GABA).

Design
We developed a model of PS in mice and evaluated, in adult offspring, visceral hypersensitivity to colorectal distension (CRD), colon inflammation, barrier function and gut microbiota taxonomy. We quantified the production of lipopeptides containing GABA by mass spectrometry in a specific strain of bacteria decreased in PS, in PS mouse colons, and in faeces of patients with IBS and healthy volunteers (HVs). Finally, we assessed their effect on PS-induced visceral hypersensitivity.

Results
Prenatally stressed mice of both sexes presented visceral hypersensitivity, no overt colon inflammation or barrier dysfunction but a gut microbiota dysbiosis. The dysbiosis was distinguished by a decreased abundance of Ligilactobacillus murinus, in both sexes, inversely correlated with visceral hypersensitivity to CRD in mice. An isolate from this bacterial species produced several lipopeptides containing GABA including C14AsnGABA. Interestingly, intracolonic treatment with C14AsnGABA decreased the visceral sensitivity of PS mice to CRD. The concentration of C16LeuGABA, a lipopeptide which inhibited sensory neurons activation, was decreased in faeces of patients with IBS compared with HVs.

Conclusion
PS impacts the gut microbiota composition and metabolic function in adulthood. The reduced capacity of the gut microbiota to produce GABA lipopeptides could be one of the mechanisms linking PS and visceral hypersensitivity in adulthood.

Leggi
Aprile 2023

Further research needed to determine first-line therapy for IBS in primary care

We read with great interest the excellent study by Carbone et al,1 which evaluated the role of a fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP)-lowering diet versus otilonium bromide (OB) in patients with irritable bowel syndrome (IBS). The study is an important addition to the growing literature evaluating the role of diets in IBS,2 but is unique by being the first to be conducted within primary care and while also delivering its dietary education via a smart phone application. The investigators found the FODMAP-lowering diet to be superior to OB at weeks 4 (62% vs 51%, p=0.02) and weeks 8 (71% vs 61%, p=0.03), and concluded that it should be considered the first-line treatment for IBS in primary care.1 However, we believe there remain unanswered questions that need to be addressed before making these recommendations. First, the response rates with a FODMAP-lowering diet…

Leggi
Aprile 2023