Dataset Information

Distinct Abnormalities of Small Bowel and Regional Colonic Volumes in Subtypes of Irritable Bowel Syndrome Revealed by MRI.

ABSTRACT:

Objectives

Non-invasive biomarkers which identify different mechanisms of disease in subgroups of irritable bowel syndrome (IBS) could be valuable. Our aim was to seek useful magnetic resonance imaging (MRI) parameters that could distinguish each IBS subtypes.

Methods

34 healthy volunteers (HV), 30 IBS with diarrhea (IBS-D), 16 IBS with constipation (IBS-C), and 11 IBS with mixed bowel habit (IBS-M) underwent whole-gut transit and small and large bowel volumes assessment with MRI scans from t=0 to t=360 min. Since the bowel frequency for IBS-M were similar to IBS-D, IBS-M and IBS-D were grouped together and labeled as IBS non-constipation group (IBS-nonC).

Results

Median (interquartile range): fasting small bowel water content in IBS-nonC was 21 (10-42), significantly less than HV at 44 ml (15-70), P<0.01 as was the postprandial area under the curve (AUC) P<0.01. The fasting transverse colon volumes in IBS-C were significantly larger at 253 (200-329) compared with HV, IBS-nonC whose values were 165 (117-255) and 198 (106-270) ml, respectively, P=0.02. Whole-gut transit time for IBS-C was prolonged at 69 (51-111), compared with HV at 34 (4-63) and IBS-D at 34 (17-78) h, P=0.03. Bloating score (VAS 0-10 cm) correlated with transverse colon volume at t=405 min, Spearman r=0.21, P=0.04.

Conclusions

The constricted small bowel in IBS-nonC and the dilated transverse colon in IBS-C point to significant differences in underlying mechanisms of disease.

SUBMITTER: Lam C

PROVIDER: S-EPMC5318666 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature

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Publications

Distinct Abnormalities of Small Bowel and Regional Colonic Volumes in Subtypes of Irritable Bowel Syndrome Revealed by MRI.

Lam Ching C Chaddock Gemma G Marciani Laurea Luca L Costigan Carolyn C Cox Eleanor E Hoad Caroline C Pritchard Susan S Gowland Penny P Spiller Robin R

The American journal of gastroenterology 20161213 2

<h4>Objectives</h4>Non-invasive biomarkers which identify different mechanisms of disease in subgroups of irritable bowel syndrome (IBS) could be valuable. Our aim was to seek useful magnetic resonance imaging (MRI) parameters that could distinguish each IBS subtypes.<h4>Methods</h4>34 healthy volunteers (HV), 30 IBS with diarrhea (IBS-D), 16 IBS with constipation (IBS-C), and 11 IBS with mixed bowel habit (IBS-M) underwent whole-gut transit and small and large bowel volumes assessment with MRI ...[more]

PMID: 27958282

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Project description:BackgroundPreclinical and clinical evidence supports the concept of bidirectional brain-gut microbiome interactions. We aimed to determine if subgroups of irritable bowel syndrome (IBS) subjects can be identified based on differences in gut microbial composition, and if there are correlations between gut microbial measures and structural brain signatures in IBS.MethodsBehavioral measures, stool samples, and structural brain images were collected from 29 adult IBS and 23 healthy control subjects (HCs). 16S ribosomal RNA (rRNA) gene sequencing was used to profile stool microbial communities, and various multivariate analysis approaches were used to quantitate microbial composition, abundance, and diversity. The metagenomic content of samples was inferred from 16S rRNA gene sequence data using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt). T1-weighted brain images were acquired on a Siemens Allegra 3T scanner, and morphological measures were computed for 165 brain regions.ResultsUsing unweighted Unifrac distances with hierarchical clustering on microbial data, samples were clustered into two IBS subgroups within the IBS population (IBS1 (n = 13) and HC-like IBS (n = 16)) and HCs (n = 23) (AUROC = 0.96, sensitivity 0.95, specificity 0.67). A Random Forest classifier provided further support for the differentiation of IBS1 and HC groups. Microbes belonging to the genera Faecalibacterium, Blautia, and Bacteroides contributed to this subclassification. Clinical features distinguishing the groups included a history of early life trauma and duration of symptoms (greater in IBS1), but not self-reported bowel habits, anxiety, depression, or medication use. Gut microbial composition correlated with structural measures of brain regions including sensory- and salience-related regions, and with a history of early life trauma.ConclusionsThe results confirm previous reports of gut microbiome-based IBS subgroups and identify for the first time brain structural alterations associated with these subgroups. They provide preliminary evidence for the involvement of specific microbes and their predicted metabolites in these correlations.

Project description:IntroductionIncreased intestinal permeability is a possible pathophysiological mechanism of irritable bowel syndrome (IBS). Increased colonic epithelial permeability is associated with visceral nociception in rodents and abdominal pain severity in IBS patients. Although IBS is more common in women, most studies on IBS-associated epithelial dysfunction have largely overlooked sex as a biologic variable.MethodsMen and women with Rome III- and Rome IV-positive IBS and HCs rated GI symptoms including abdominal pain severity at baseline, 24 h prior and immediately post procedure. Epithelial function was assessed ex vivo in Ussing chambers using sigmoid colon biopsies, by monitoring short-circuit current (Isc), transepithelial electrical resistance (TEER) and mucosal permeability to FITC-dextran 4 kDa (FD4). Biopsies tight junction protein mRNA expression was assessed using RNA seq. Statistical analyses included a framework of General Linear Models and linear contrast analyses performed using R software.Results44 IBS patients (66% women, 30 years) and 19 HCs (53% women, 28 years) were enrolled. The proportion of women was not different between groups. As a group, IBS patients exhibited lower TEER compared to HCs (16.9 ± 5.5 vs. 21.5 ± 6.5 Ω/cm2, p = 0.01, FDR = 0.02), but no difference in FD4 serosal concentration or Isc (basal or stimulated). Within men, IBS had lower TEER vs. HCs, but there was no disease difference within women. Independent of diagnosis, women had 1.3-fold lower TEER concentration and 1.5-fold higher FD4 serosal concentration than men. These sex differences were also seen within HCs, although within IBS, FD4 permeability only showed a trend to be higher in women vs. men. Abdominal pain ratings and IBS severity scores were not associated with TEER or FD4 concentration.DiscussionOur study confirms prior reports that IBS patients demonstrate altered sigmoid colonic epithelial function and shows for the first time that these are independent of sex. However, sex differences in sigmoid colonic epithelial function are observed independently of disease status. Further studies are needed to delineate if intestinal permeability interacts with other factors in the pathophysiology of IBS and if these interactions differ by sex.

Dataset Information

Distinct Abnormalities of Small Bowel and Regional Colonic Volumes in Subtypes of Irritable Bowel Syndrome Revealed by MRI.

Objectives

Methods

Results

Conclusions

Publications

Distinct Abnormalities of Small Bowel and Regional Colonic Volumes in Subtypes of Irritable Bowel Syndrome Revealed by MRI.

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