1. Abstract Fermentable fibres such as inulin can support metabolic health but may exacerbate gastrointestinal symptoms in individuals with irritable bowel syndrome (IBS) due to rapid fermentation and gas production. The gel-forming fibre psyllium improves IBS symptoms, although the underlying mechanisms remain unclear. We hypothesised that fibre gelation alters fermentation by modulating microbial access to substrates. To test this, we compared psyllium with methylcellulose, a chemically modified, gel-forming fibre, to determine the effects of gelation on inulin fermentation. Inulin alone or combined with psyllium or methylcellulose was fermented for 48 hrs in a colonic fermentation model inoculated with healthy human faeces. Gas production, metabolite profiles, microbial community composition and microbial localisation within fibre gels were assessed. Bioactivity of fermentation products was evaluated in STC-1 cells. Psyllium co-fermentation significantly accelerated fermentation and enhanced production of metabolites, while methylcellulose had minimal effects. Psyllium maintained higher diversity and enriched polysaccharide-degrading taxa including Bacteroides and Phoecaeicola species, which were strongly associated with metabolic activity. Bacterial penetration into the psyllium matrix was observed but not into methylcellulose. Fermentation products from psyllium but not methylcellulose stimulated GLP-1 and 5-HT secretion in STC-1 cells. These findings demonstrate that delayed-onset fermentable gel-forming fibres enhance microbial access to entrapped substrates, driving metabolic and hormonal responses.

Sodium alginates are widely used for their gelling, thickening, and stabilizing properties. Raft-producing formulations have been used widely for many years to treat the symptoms of anti-reflux disease and those suffering occasional symptoms. The aim of this study was to determine the feasibility of characterizing rafts formed from alginate-containing anti-reflux formulations in vivo using either a supine high-field 3T scanner or an upright low-field 0.5T MRI scanner. Six healthy participants (one male, five female, age range 23-50 years) attended three study visits following an overnight fast and were scanned at one field strength (N = 3 at 0.5T, N = 3 at 3T) before and after ingestion of an acidic drink followed by one of three different alginate antireflux formulations. These formulations had identical quantities (by mass) of sodium alginate, calcium carbonate, and sodium bicarbonate. Raft position and volume were measured along with gastric contents and gas using T2-weighted MRI. Additionally, the image textures of the raft and T2 properties were investigated at 3T. In vitro properties (raft strength, mass, and NMR chemical analysis) of the three different formulations were also determined. Alginate rafts were generated in all volunteers for all formulations. Gastric emptying of the acidic drink was consistent across all study days. Raft volumes measured showed some differences between body positions, with upright maintaining a higher volume of raft for longer. In vitro analysis showed significant differences in strength and mass between two of the formulations, which were likely caused by differences in the chemical structure of the alginates used in the formulations. In conclusion, characterization of anti-reflux alginate raft properties can be achieved using both low-field upright and high-field supine MRI. Larger scale studies are needed to determine the differences between formulations in vivo.

BACKGROUND AND AIMS:The primary aim of this study was to evaluate the effect of ingestion of a standardized meal on gastric content volume and gastric emptying time in healthy normal weight people and those with obesity. Secondary aims were to evaluate the effect of the meal on superior mesenteric artery blood flow, small bowel water content, subjective satiety, and concentrations of appetite and motility-regulating hormones (PYY, ghrelin, GLP-1, and GLP-2), blood glucose and insulin in the participants. METHODS:Ten normal weight male participants and ten with obesity were recruited. After fasted measurements participants consumed a test meal [∼500 g portion, 145 kcal (606 kJ)/100 g]. T50 gastric emptying time, gastric content volume, superior mesenteric artery blood flow and small bowel water content were measured using magnetic resonance imaging. Blood PYY, ghrelin, GLP-1, GLP-2, insulin and glucose were measured along with composite satiety scores. Measurements were repeated at regular intervals for up to 300 min. RESULTS:At screening, there were no differences between the groups apart from greater body weight and body mass index in those with obesity. Median ± SD T50 gastric emptying time was not different between normal weight participants and those with obesity (148 ± 16 min vs. 170 ± 15 min, respectively, P = 0.87). Gastric content volume, blood glucose, PYY, ghrelin, active GLP-1 and total GLP-2 concentrations, superior mesenteric artery blood flow, and small bowel water content, when fasted and in response to eating did not differ between groups (all P > 0.05). Repeated measures ANOVA showed no difference in postprandial blood glucose concentrations (P = 0.486) over time between the groups, but postprandial serum insulin was significantly higher (P = 0.015) in those with obesity. Composite satiety scores were significantly higher in the normal weight group immediately after eating and in the postprandial period (P = 0.015). CONCLUSION:Lower meal-stimulated satiety in males with obesity could lead to greater habitual dietary intake and further weight gain and, therefore, be an important driver for the maintenance of obesity in individuals without comorbidities.

BackgroundThere is a paucity of knowledge on the longer-term effects of CF transmembrane conductance regulator (CFTR) modulator therapies upon the gut microbiome and associated outcomes. In a pilot study, we investigated longitudinal Elexacaftor/Tezacaftor/Ivacaftor (ETI) therapy on the gut microbiota, metabolomic functioning, and clinical outcomes in people with CF (pwCF).Study designFaecal samples from 20 pwCF were acquired before and then following 3, 6, and 17+ months of ETI therapy. Samples were subjected to microbiota sequencing and targeted metabolomics to profile and quantify short-chain fatty acid composition. Ten healthy matched controls were included for comparison. Clinical data, including markers of intestinal function were integrated to investigate relationships.ResultsExtended ETI therapy increased core microbiota diversity and composition, which translated to gradual shifts in whole microbiota composition towards that observed in healthy controls. Despite becoming more similar over time, CF microbiota and functional metabolite compositions remained significantly different to healthy controls. Antibiotic treatment for pulmonary infection significantly explained a relatively large degree of variation within the whole microbiota and rarer satellite taxa. Clinical outcomes were not significantly different following ETI.ConclusionsWhilst differences persisted, a positive trajectory towards the microbiota observed in healthy controls was found. We posit that progression was predominately impeded by pulmonary antibiotics administration. We recommend future studies use integrated omics approaches within a combination of long-term longitudinal patient studies and model experimental systems. This will deepen our understanding of the impacts of CFTR modulator therapy and respiratory antibiotic interventions upon the gut microbiome and gastrointestinal pathophysiology in CF.

Abstract Background Management and assessment of fibrostenotic Crohn’s disease(CD) is a research priority. Deep phenotyping is key for effective therapeutic development. In this study, we explore MRI assessed bowel motility before and after endoscopic stent treatment of focal fibrotic strictures in patients with CD. Methods Patients (n = 12, median age = 51 y) undergoing removable stent treatment were recruited as part of an approved study. Average CD diagnosis was 31y (range 16-57 y). All strictures were fibrotic in nature- three were de novo, while the remaining were anastomotic (ileocolonic). All patients had symptoms attributable to focal stricturing. Each patient had an MR – Enterography (MRE) scan (median 21 weeks) before and after (median 17 weeks) stent dilation. MR – Enterography (MRE) protocol included oral preparation, anatomical and cine ‘motility’ sequences across the abdomen in 20s breath hold (1 image/second). Motility sequences were processed with CE/FDA cleared GIQuant (Motilent, UK) to produce a quantitative map from which, objective data could be generated across the bowel. Stricture assessment was performed by a consultant radiologist. Non parametric statistics were used to investigate the following questions: 1. Was the baseline regional motility (mean, range) at stricture, dilation and morphologically normal bowel different across patients (Kruskal-Wallis)? 2. What were the changes in stricture motility pre and post stent placement (Wilcoxin Rank)? 3. Was stricture motility associated with stricture morphology (Spearman’s Rho)? Results 1. Motility at the stricture (126, range 62 to 139), pre-stenotic terminal ileum (252, range 80 to 478) and the global small bowel (269, range 166 to 339) was varied across the cohort (P < 0.001). 2. All patients had improvement in symptom scores & reporting, without change in stricture motility (P = 0.94). 3. A positive change in stricture motility was associated with reduced length of pre stricture dilatation (R = 0.64, P = 0.02) Conclusion Strictured intestine displayed reduced motility compared with adjacent bowel segments. While reduced, peristalsis was still present although paired analysis suggested no change pre and post stent stricture management. This implies that symptomatic relief was not related to altered peristalsis across the study. Finally, the length of dilation did appear to be associated with dynamic changes in stricture motility. In summary, as noted in stent-treated CD strictures, a dynamic physiological environment exists which can be captured with Cine MRI. These motility assessments, which have been studied as a proxy indicator of active CD, represent the first reported dynamic motility outcomes following stricture intervention.

Purpose: Knowledge of the length of the colon is relevant to understanding physiological and pathological function. It also has implications for diagnostic and clinical interventions, as well as for the design of delayed-release drug formulations and drug disposition modeling. Methods: Over the years, a range of different experimental methods have been employed to assess colon length. These methods vary from direct measurements on cadavers and during intraoperative procedures to measurements obtained from endoscopic and medical imaging techniques. However, no systematic review or meta-analysis of these findings has yet been carried out. In this systematic review, we identified 31 published experimental studies that measured the length of the human colon and/or its segments. Results: We synthesized the available data, comprising colon length measurements from 5741 adults and 337 children and young people, in a meta-analysis. The data contribute to our understanding of colon morphology and may have implications for clinical practice, particularly for colonoscopy and preoperative planning of surgical resections. Additionally, this review provides potential insights into anatomical correlates of functional diseases, such as constipation. Conclusions: This review highlights that non-invasive, non-destructive diagnostic imaging techniques, such as magnetic resonance imaging (MRI), can provide more physiologically relevant measurements of colon length. However, there is a need for more standardized measurement protocols and for additional pediatric data.

Abstract Background In Crohn’s Disease (CD), 10% of patients present with fibrostenosis with a further 10% progressing from inflammatory to a fibrostenotic disease behaviour over 7 years. 40% of fibrostenotic CD patients need surgery at 5 years compared to ~10% with inflammatory disease. Present non-invasive fibrosis biomarkers lack the required accuracy needed to be used routinely for clinical decision making. T1, T2, diffusion weighted imaging, motility and bowel volumes have shown promise in the non-invasive measure of fibrosis. Methods The primary objective of this study is to undertake biological validation of MRI measures as independent imaging biomarkers of histological fibrosis with the primary outcome being the correlation between MRI measures and histological fibrosis measures. GI-Seg (Motilent, London, UK) is an image analysis tool used to segment the gastrointestinal tract on T2W MRI scans. Patients with CD histological diagnosis and in need of surgical resection for stenosis attended a one-hour 3T MRI scanning session within 12 weeks prior to their intestinal resection surgery. Histological samples were scored by a specialized gastrointestinal pathologist for inflammation, fibrosis, and muscular hypertrophy. An expert radiologist with the help of the histopathologist located the strictures on DWI, quantitative T2&T2 scans, and T2 weighted clinical MRI scans. GI-Seg was used to generate a 3D model of the stricture on T2W scans measuring bowel wall volume and average signal intensity of each stricture. Pearson correlation coefficient was used to quantify the correlation between the variables. Results A total of 10 CD patients, encompassing 20 strictures, were included in the study. The analysis revealed that the average T2 signal has a significant correlation with global fibrosis scores (r(20) = .563, p = .010) (Figure) and total inflammation scores (r(20) = .451, p = .046). Additionally, stricture volume showed a fair correlation with chronic inflammation component scores (r(20) = .453, p = .045). Notably, quantitative T1 values correlated with total inflammation scores (r(17) = .493, p = .045). Conclusion The study reveals fair correlations between the T2 signal average and both global fibrosis and global inflammation scores, as well as between stricture volume and chronic inflammation in CD strictures. While these findings indicate that the GI-seg tool's measurements of bowel wall volume and signal intensity have potential utility as imaging biomarkers for fibrosis and inflammation, the results also underscore the necessity for additional markers that are specifically correlated with fibrosis. Such markers are essential to distinctly identify fibrotic changes, independent of inflammatory processes.

Milk structural assemblies (e.g., casein micelles) occur naturally and can be altered during processing, and this may influence the milk's nutritional properties. Heat treatment of dairy ensures microbiological safety and extends shelf-life. Both pasteurisation and ultra-high temperature (UHT) processing are known to alter natural structural assemblies, but despite widespread use, only four human studies have addressed how heat treatment affects nutrient delivery. In vitro, animal, and human models have all shown more rapid nutrient release or appearance from UHT vs. pasteurised milk, with altered gastric emptying rate proposed as a mechanism. We hypothesised that differences in bovine milk structural assemblies arising from different processing methods would speed up gastric emptying and nutrient delivery following consumption of UHT relative to pasteurised milk. A randomised double-blind crossover trial assessed gastric emptying rate (using magnetic resonance imaging measuring gastric content volume) over 3 h and plasma amino acid appearance (using ultra-performance liquid chromatography) over 5 h following 500 mL of each milk in healthy women (n = 20). Gastric electrical activity was measured using body surface gastric mapping, and abdominal distension using stretch sensors. The time to empty 25% of the stomach contents was greater following UHT vs. pasteurised milk (45 ± 4 vs. 33 ± 4 min p < 0.05). While gastric content remained greater for longer following UHT milk, the incremental area under the curve of plasma essential amino acids was greater than pasteurised milk (55324 ± 3809 vs. 36598 ± 5673 μmol·min·L−1 p < 0.05). The greater amino acid appearance following UHT milk aligns with more rapid release of proteins from the gastric curd observed in vitro, yet the greater gastric content volume implies gastric content composition (e.g., solid vs. liquid) is an important determinant of nutrient release. Dairy processing using different heat treatments, which induced structural modifications, impacted gastric emptying and plasma amino acid appearance, with implications for appetite regulation and nutrient utilisation for metabolism.

Bisacodyl is a widely used laxative that stimulates both motility and secretion. Our aim was to exploit the unique capabilities of MRI to define bisacodyl's mode of action. Two placebo-controlled cross-over trials were performed, one using a single dose of Bisacodyl 5 mg while the second dosed daily for 3 consecutive days. Serial MRI was performed every 75 minutes. Primary endpoint: ascending colon water content as assessed by T1AC AUC300-450 minutes. Secondary endpoints included: small bowel water content, whole gut transit time (WGTT), colonic volumes, stool frequency, and consistency using Bristol Stool Form Score (BSFS). Exploratory endpoints: changes in the serial segmental volumes were quantified from the number of "mass movements" defined as episodes when segmental volume change from the previous scan was > 20% of baseline volume. We also measure the time to defecate after dosing. After 3 days of bisacodyl, ascending colon water content (T1) was 62% greater than after placebo, mean difference T1 AUC300-450 minutes 50.2 (61.0) sec.min, 95% CI (9.2, 91.2), P = 0.02, while after a single dose difference was only 11% (P = 0.58). Both single and repeated doses shortened WGTT (P < 0.049) and time to defecate (P 0.01). Only repeated doses significantly increased small bowel water content (P < 0.03), the number of "mass movements" (P = 0.048), bowel frequency (P = 0.006), and BSFS (P = 0.03). Repeated, compared to single dosing of Bisacodyl, additionally increases small bowel and colon water content and increases the number of "mass movements" thereby increasing its laxative effect. MRI is a non-invasive, patient-acceptable technique for evaluating drugs which alter secretion and/or motility.

White rice has a high glycemic index and its consumption has been linked to an increased risk of developing type-2 diabetes mellitus, increased diabetes associated complications and obesity. In recent in vitro studies we have shown that addition of food hydrocolloids, such as low acyl gellan gum (LAGG), when cooking white rice potentially modifies starch digestion kinetics. The impact in vivo remains to be investigated. We aimed to determine the effect of adding LAGG to white rice on postprandial glycemic, gastrointestinal and appetitive responses in humans. Following LAGG in vitro characterisation, 12 healthy adults participated in a randomised, controlled, crossover study. They consumed isoenergetic meals of jasmine white rice (232 kcal) cooked with (Rice + LAGG) and without (Rice control) 3 % w/dry rice w LAGG. Blood glucose, intragastric meal appearance, meal volume and appetite were assessed serially for 2 h. The incremental area under the curve over two hours (iAUC2h) for blood glucose for the Rice + LAGG meal (93 ± 16 mmol/L·min) was significantly lower than that for the Rice control meal (160 ± 18 mmol/L·min), P=0.0007. Blood glucose rose postprandially to a peak at T=30 min, with the Rice control meal peak (7.3 ± 0.2 mmol/L) significantly higher than that for the Rice + LAGG meal (6.5 ± 0.2 mmol/L), P < 0.01. MRI images showed that for Rice + LAGG there were multiple rice boluses persisting intragastrically throughout the digestion time. There were no significant differences in appetite between meals. The addition of LAGG to the cooking process was effective in reducing postprandial blood glucose responses in healthy humans. If confirmed, this could potentially provide a simple and relatively inexpensive intervention to reduce the post prandial glycemic response to white rice.

BACKGROUND:Lactulose is a laxative which accelerates transit and softens stool. Our aim was to investigate its mechanism of action and use this model of diarrhea to investigate the anti-diarrheal actions of ondansetron. METHODS:A double-blind, randomized, placebo-controlled crossover study of the effect of ondansetron 8 mg in 16 healthy volunteers. Serial MRI scans were performed fasted and 6 h after a meal. Participants then received lactulose 13.6 g twice daily and study drug for a further 36 h. On Day 3, they had further serial MRI scans for 4 h. Measurements included small bowel water content (SBWC), colonic volume, colonic gas, small bowel motility, whole gut transit, and ascending colon relaxation time (T1AC), a measure of colonic water content. KEY RESULTS:Lactulose increased area under the curve (AUC) of SBWC from 0 to 240 min, mean difference 14.2 L · min (95% CI 4.1, 24.3), p = 0.009, and substantially increased small bowel motility after 4 h (mean (95% CI) 523 (457-646) a.u. to 852 (771-1178) a.u., p = 0.007). There were no changes in T1AC after 36 h treatment. Ondansetron did not significantly alter SBWC, small bowel motility, transit, colonic volumes, colonic gas nor T1AC, with or without lactulose. CONCLUSION & INFERENCES:Lactulose increases SBWC and stimulates small bowel motility; however, unexpectedly it did not significantly alter colonic water content, suggesting its laxative effect is not osmotic but due to stimulation of motility. Ondansetron's lack of effect on intestinal water suggests its anti-diarrheal effect is not due to inhibition of secretion but more likely altered colonic motility.

BACKGROUND & AIMS:Currently, the main treatment for celiac disease (CD) is the gluten-free diet (GFD). This observational cohort study investigated the impact of CD and 1 year of GFD on gut function and microbiome. METHODS:A total of 36 newly diagnosed patients and 36 healthy volunteers (HVs) were studied at baseline and at 12-month follow-up. Small bowel water content (SBWC), whole gut transit time (WGTT), and colon volumes were measured by magnetic resonance imaging. Stool sample DNA was subjected to shotgun metagenomic sequencing. Species-level abundances and gene functions, including CAZymes (carbohydrate active enzymes) were determined. RESULTS:SBWC was significantly higher in people with CD (157 ± 15 mL) vs (HVs 100 ± 12 mL) (P = .003). WGTT was delayed in people with CD (68 ± 8 hours) vs HVs (41 ± 5 hours) (P = .002). The differences reduced after 12 months of GFD but not significantly. Well-being in the CD group significantly improved after GFD but did not recover to control values. CD fecal microbiota showed a high abundance of proteolytic gene functions, associated with Escherichia coli, Enterobacter, and Peptostreptococcus. GFD significantly reduced Bifidobacteria and increased Blautia wexlerae. Microbiome composition correlated positively with WGTT, colonic volume, and Akkermansia municphilia but negatively with B wexerelae. Following GFD, the reduction in WGTT and colonic volume was significantly associated with increased abundance of B wexlerae. There were also significant alterations in CAZyme profiles, specifically starch- and arabinoxylan-degrading families. CONCLUSIONS:CD impacted gut function and microbiota. GFD ameliorated but did not reverse these effects, significantly reducing Bifidobacteria associated with reduced intake of resistant starch and arabinoxylan from wheat. CLINICALTRIALS:gov, number: NCT02551289.

Background People with cystic fibrosis (CF) can experience recurrent chest infections, pancreatic exocrine insufficiency and gastrointestinal symptoms. New cystic fibrosis transmembrane conductance regulator (CFTR) modulator drugs improve lung function but gastrointestinal effects are unclear. We aimed to see if a CFTR modulator (tezacaftor-ivacaftor,TEZ/IVA) improves gastrointestinal outcomes in CF. Methods We conducted a randomised, double-blind, placebo-controlled, two-period crossover trial (2019-2020) at Nottingham University Hospitals. The effects of TEZ/IVA on gut physiology were measured using MRI. Participants were randomly assigned to treatment sequences AB or BA (A:TEZ/IVA, B:placebo, each 28 days), with a 28-day washout period. Participants had serial MRI scans at baseline and after 19-23 days of each treatment. Due to the COVID-19 pandemic, a protocol amendment allowed for observer-blind comparisons prior to and during TEZ/IVA. In such cases, participants were not blind to the treatment but researchers remained blind. The primary outcome was oro-caecal transit time (OCTT). Secondary outcomes included MRI metrics, symptoms and stool biomarkers. Results We randomised 13 participants. Before the COVID-19 pandemic 8 participants completed the full protocol and 1 dropped out. The remaining 4 participants followed the amended protocol. There were no significant differences between placebo and TEZ/IVA for OCTT (TEZ/IVA >360minutes [225,>360] vs. placebo 330minutes [285,>360], p=0.8) or secondary outcomes. There were no adverse events. Conclusions Our data contribute to a research gap in the extra-pulmonary effects of CFTR modulators. We found no effect after TEZ/IVA on MRI metrics of gut function, GI symptoms or stool calprotectin. Effects might be detectable with larger studies, longer treatment or more effective CFTR modulators. ClinicalTrials.gov registration NCT04006873 (02/07/2019)