Gastrointestinal peptides and small-bowel hypomotility are possible causes for fasting and postprandial symptoms in active Crohn's disease

Magnetic Resonance Imaging Reveals Novel Insights into the Dual Mode of Action of Bisacodyl: A Randomized, Placebo-controlled Trial in Constipation

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.

The role of nutrient sensing dysregulation in anorexia of ageing: The little we know and the much we don't

The age-related decline in appetite and food intake - termed "anorexia of ageing" - is implicated in undernutrition in later life and hence provides a public health challenge for our ageing population. Eating behaviour is controlled, in part, by homeostatic mechanisms which sense nutrient status and provide feedback to appetite control regions of the brain. Such feedback signals, propagated by episodic gut hormones, are dysregulated in some older adults. The secretory responses of appetite-related gut hormones to feeding are amplified, inducing a more anorexigenic signal which is associated with reduced appetite and food intake. Such an augmented response would indicate an increase in gut sensitivity to nutrients. Consequently, this review explores the role of gastrointestinal tract nutrient sensing in age-related appetite dysregulation. We review and synthesise evidence for age-related alterations in nutrient sensing which may explain the observed hormonal dysregulation. Drawing on what is known regarding elements of nutrient sensing pathways in animal models, in other tissues of the body, and in certain models of disease, we identify potential causal mechanisms including alterations in enteroendocrine cell number and distribution, dysregulation of cell signalling pathways, and changes in the gut milieu. From identified gaps in evidence, we highlight interesting and important avenues for future research.

Effects of opium tincture on gastrointestinal function and motility in healthy volunteers: A magnetic resonance imaging study

BACKGROUND

Opioids inhibit motility and secretion of the gut and have been used for antidiarrheal treatment for centuries. However, the underlying mechanisms of opium tincture are not evident.

AIM

To investigate the effects of opium tincture on gastrointestinal motility, intestinal volumes, and water content of different gut segments assessed by magnetic resonance imaging (MRI).

METHODS

Twenty healthy volunteers were included in a randomized, placebo-controlled, crossover study of 9 days of treatment with 30 drops of opium tincture per day. MRI was performed on day 1 (before treatment) and day 9 (during treatment). Measurements included assessments of gastric volume, gastric emptying, gastric motility, small bowel volume, small bowel water content, small bowel motility, colon volume, colon water content, and whole gut transit.

KEY RESULTS

Opium tincture delayed gastric emptying by a mean difference of 5.6 min [95% CI: 1.8-9.4], p = 0.004, and increased postprandial gastric meal volume (17-21%, p = 0.02). Small bowel endpoints did not change. Opium tincture delayed whole gut transit time (p = 0.027) and increased ascending colon volume by 59 mL [95% CI: 15-103], p = 0.004, and transverse colon volume by 48 mL [95% CI: 4-92], p = 0.027. T1-relaxation time of the descending colon chyme was decreased during opium treatment, indicating dryer feces (difference: -173 ms [95% CI: -336 -11], p = 0.03).

CONCLUSION AND INFERENCES

Opium tincture induced changes in the stomach and colon in healthy volunteers. An improved understanding of how opioids affect gut functions may lead to a better understanding and optimized management of diarrhea.

MRI tagging of colonic chyme mixing in healthy subjects: Inter-observer variability and reliability of the measurement with time

BACKGROUND

Magnetic resonance imaging (MRI) tagging techniques have been applied to the GI tract to assess bowel contractions and content mixing. We aimed to evaluate the dependence of a tagging measurement (for assessing chyme mixing) on inter-observer variability in both the ascending colon (AC) and descending colon (DC) and to investigate the temporal variation and hence reliability of the colonic tagging technique by acquiring multiple measurements over time on healthy participants.

METHODS

Two independent datasets of healthy adults were used for the retrospective inter-observer variability (Study 1: 13 datasets and Study 2: 31 datasets), and ten participants were scanned for the prospective temporal variation study following a 1 L mannitol oral preparation. All colonic tagging data were acquired on 3 T MRI scanners. The mean and the standard deviation (SD) maps were generated pixel-by-pixel using custom-written software in MATLAB. The colonic regions of interest were defined using MIPAV software. Bland-Altman plots and scatter plots were used for the inter-observer variability. The mean and SD of all repeated measures for each subject were calculated along with a one-way ANOVA to test for variations with time.

RESULTS

Scatter plots and Bland-Altman plots showed a large range of data with low variation and small limits of agreements (<5% CoV). The intraclass correlation coefficient of inter-rater reliability was excellent and 0.97 or above for the AC and DC measurements for both datasets. The temporal variation study shows that there was no significant difference found between the multiple measures with time (p = 0.53, one-way repeated measures ANOVA test).

CONCLUSIONS

MRI tagging technique can provide an assessment of colonic chyme mixing. The inter-observer study data showed high inter-rater agreement. The temporal variation study showed some individual variations with time suggesting multiple measurements may be needed to increase accuracy.

Intestinal Enteroendocrine Cells: Present and Future Druggable Targets

Enteroendocrine cells are specialized secretory lineage cells in the small and large intestines that secrete hormones and peptides in response to luminal contents. The various hormones and peptides can act upon neighboring cells and as part of the endocrine system, circulate systemically via immune cells and the enteric nervous system. Locally, enteroendocrine cells have a major role in gastrointestinal motility, nutrient sensing, and glucose metabolism. Targeting the intestinal enteroendocrine cells or mimicking hormone secretion has been an important field of study in obesity and other metabolic diseases. Studies on the importance of these cells in inflammatory and auto-immune diseases have only recently been reported. The rapid global increase in metabolic and inflammatory diseases suggests that increased understanding and novel therapies are needed. This review will focus on the association between enteroendocrine changes and metabolic and inflammatory disease progression and conclude with the future of enteroendocrine cells as potential druggable targets.

Small bowel water content assessed by MRI in health and disease: a collation of single-centre studies

BACKGROUND

New developments in MRI have allowed the non-invasive, accurate measurement of the small bowel water content (SBWC).

AIMS

To collate studies measuring SBWC following ingestion of a range of foods in both health and disease to provide data for adequately powering future studies in this area.

METHODS

This collation brings together 29 studies including 954 participants (530 healthy, 54 diverticulosis, 255 IBS, 53 functional constipation, 12 cystic fibrosis, 15 Crohn's disease, 20 coeliac disease, 15 scleroderma) which have been carried out in a single centre using comparable study designs.

RESULTS

Fasting SBWC (mean 82 [SD 65] mL) shows high variability with a small decline with advancing age (healthy volunteers only; individual patient data). Fasting values are increased in untreated coeliac disease (202 [290] mL, P = 0.004). Post-prandial SBWC shows less intra-individual variability than fasting values in healthy volunteers. SBWC is increased by eating, most markedly by high fat meals but also by fibre, both viscous and particulate. Indigestible residue accumulates in late post-prandial period but empties soon after ingestion of a high calorie meal which produces a significant drop (by 50 [52] mL) in healthy volunteers. The associated fall in SBWC is abnormal in people with cystic fibrosis (SBWC reduced by 10 [121] mL, P = 0.002) and in people with irritable bowel syndrome with diarrhoea (SBWC reduced by 17 [43] mL, P = 0.007).

CONCLUSIONS

SBWC as assessed by MRI is a valuable biomarker indicating the balance of secretion and absorption in health and disease and the impact of treatments.

Magnetic resonance imaging of the gastrointestinal tract shows reduced small bowel motility and altered chyme in cystic fibrosis compared to controls

People with cystic fibrosis (CF) experience digestive symptoms but the mechanisms are incompletely understood. Here we explore causes and consequences of slower gastrointestinal transit using magnetic resonance imaging (MRI). Twelve people with CF and 12 healthy controls, matched for age and gender, underwent MRI scans, both fasted and after standardised meals, over 6.5 h. Fasted small bowel motility scores were lower in CF than in controls. No difference in ascending colon chyme T₁ was detected. The difference in texture between small bowel and colon contents, seen in health, was diminished in CF. The ascending colon in CF participants had an abnormal appearance compared to controls. MRI offers unique potential to evaluate gut luminal content, colonic mucosa and intestinal motor activity. These new data support the theoretical cycle of desiccation, dysmotility and delayed transit as a cause of gastrointestinal symptoms in CF.

The dietary practices and beliefs of people living with older-onset inflammatory bowel disease

BACKGROUND AND OBJECTIVES

The role of diet in inflammatory bowel disease (IBD) remains incompletely understood. Studies have previously examined dietary practices in IBD, but none have specifically focused on older-onset disease. IBD may put vulnerable groups at risk of nutritional deficiency and associated complications, potentially heightened by comorbidities, frailty and polypharmacy. Our objective was to describe dietary practices and beliefs in older-onset IBD.

METHODS

A questionnaire exploring dietary practices and beliefs was prospectively administered to 137 people with older-onset IBD attending gastroenterology clinics.

RESULTS

Thirty-two percent believed diet was the initiating factor for their IBD. This was significantly more likely in people with Crohn's disease than ulcerative colitis (P = 0.05) and in those who felt limited in their dietary choices due to cost (P = 0.008). Forty-three percent believed diet could trigger IBD relapse and 68% avoided dietary components to avoid relapse. Most frequently avoided were spicy and fatty foods, carbonated drinks, red meat, alcohol and raw fruit and vegetables. Twenty-two percent of participants had tried a whole food exclusion diet, most frequently gluten- or lactose-free. Almost a third avoided eating out (29%) or eating the same meal as their family (32%) to prevent relapse. Respondents rarely relied upon healthcare professionals or patient support organisations for their dietary information.

CONCLUSION

Individuals with older-onset IBD report dietary practices with a high degree of consistency. Dietary avoidance may impact upon both nutritional and psychosocial wellbeing in this more vulnerable group and, as such, early dietetic assessment could help improve outcomes.

Automatic detection of Crohn's disease using quantified motility in magnetic resonance enterography: initial experiences

AIM

To report initial experiences of automatic detection of Crohn's disease (CD) using quantified motility in magnetic resonance enterography (MRE).

MATERIALS AND METHODS

From 302 patients, three datasets with roughly equal proportions of CD and non-CD cases with various illnesses were drawn for testing and neural network training and validation. All datasets had unique MRE parameter configurations and were performed in free breathing. Nine neural networks were devised for automatic generation of three different regions of interests (ROI): small bowel, all bowel, and non-bowel. Additionally, a full-image ROI was tested. The motility in an MRE series was quantified via a registration procedure, which, accompanied with given ROIs, resulted in three motility indices (MI). A subset of the indices was used as an input for a binary logistic regression classifier, which predicted whether the MRE series represented CD.

RESULTS

The highest mean area under the curve (AUC) score, 0.78, was reached using the full-image ROI and with the dataset with the highest cine series length. The best AUC scores for the other two datasets were only 0.54 and 0.49.

CONCLUSION

The automatic system was able to detect CD in the group of MRE studies with lower temporal resolution and longer cine series showing potential in primary bowel disorder diagnostics. Larger ROI selections and utilising all available cine series for motility registration yielded slight performance improvements.

The role of incretins and incretin-based drugs in autoimmune diseases

Incretin hormones, including glucagon-like peptide (GLP)-1, GLP-2 and glucose-dependent insulinotropic polypeptide (GIP), are gastrointestinal peptides secreted from enteroendocrine cells. These hormones play significant roles in many physiological processes via binding to G-protein coupled receptors (GPCRs) on different organs and tissues; one of them is the immunomodulatory effect on the immune system and its molecular components such as cytokines and chemokines. Anti-inflammatory effects of incretins and dependent molecules involving long-acting analogs and DPP4 inhibitors through regulation of T and B cell activation may attenuate autoimmune diseases caused by immune system disorders in mistakenly recognizing self as the foreign agent. In this review, we investigate incretin effects on the immune system response and the potential benefits of incretin-based therapy for treating autoimmune diseases.

Reduction in GLP-1 secretory capacity may be a novel independent risk factor of coronary artery stenosis

Multiple factors regulate glucagon-like peptide-1 (GLP-1) secretion, but a group of apparently healthy subjects showed blunted responses of GLP-1 secretion in our previous study. In this study, we examined whether the reduction in GLP-1 secretory capacity is associated with increased extent of coronary artery stenosis in non-diabetic patients. Non-diabetic patients who were admitted for coronary angiography without a history of coronary interventions were enrolled. Coronary artery stenosis was quantified by Gensini score (GS), and GS ≥ 10 was used as an outcome variable based on its predictive value for cardiovascular events. The patients (mean age, 66.5 ± 8.8 years; 71% males, n = 173) underwent oral 75 g-glucose tolerant tests for determination of glucose, insulin and active GLP-1 levels. The area under the curve of plasma active GLP-1 (AUC-GLP-1) was determined as an index of GLP-1 secretory capacity. AUC-GLP-1 was not correlated with fasting glucose, AUC-glucose, serum lipids or indices of insulin sensitivity. In multivariate logistic regression analysis for GS ≥ 10, AUC-GLP-1 < median, age and hypertension were selected as explanatory variables, though fasting GLP-1 level was not selected. The findings suggest that reduction in GLP-1 secretory capacity is a novel independent risk factor of coronary stenosis.

GLP-1 and Intestinal Diseases

Accumulating evidence implicates glucagon-like peptide-1 (GLP-1) to have, beyond glucose maintenance, a beneficial role in the gastrointestinal tract. Here, we review emerging data investigating GLP-1 as a novel treatment for intestinal diseases, including inflammatory bowel diseases, short-bowel syndrome, intestinal toxicities and coeliac disease. Possible beneficial mechanisms for these diseases include GLP-1′s influence on gastric emptying, its anti-inflammatory properties and its intestinotrophic effect. The current knowledge basis derives from the available GLP-1 agonist treatments in experimental animals and small clinical trials. However, new novel strategies including dual GLP-1/GLP-2 agonists are also in development for the treatment of intestinal diseases.

Growth Delay in Inflammatory Bowel Diseases: Significance, Causes, and Management

Growth delay with height and weight impairment is a common feature of pediatric inflammatory bowel diseases (PIBD). Up to 2/3 of Crohn Disease patients have impaired weight at diagnosis, and up to 1/3 have impaired height. Ulcerative colitis usually manifests earlier with less impaired growth, though patients can be affected. Ultimately, growth delay, if not corrected, can reduce final adult height. Weight loss, reduced bone mass, and pubertal delay are also concerns associated with growth delay in newly diagnosed PIBD patients. The mechanisms for growth delay in IBD are multifactorial and include reduced nutrient intake, poor absorption, increased fecal losses, as well as direct effects from inflammation and treatment modalities. Management of growth delay requires optimal disease control. Exclusive enteral nutrition (EEN), biologic therapy, and corticosteroids are the primary induction strategies used in PIBD, and both EEN and biologics positively impact growth and bone development. Beyond adequate disease control, growth delay and pubertal delay require a multidisciplinary approach, dependent on diligent monitoring and identification, nutritional rehabilitation, and involvement of endocrinology and psychiatry services as needed. Pitfalls that clinicians may encounter when managing growth delay include refeeding syndrome, obesity (even in the setting of malnutrition), and restrictive diets. Although treatment of PIBD has improved substantially in the last several decades with the era of biologic therapies and EEN, there is still much to be learned about growth delay in PIBD in order to improve outcomes.

The Gut-Brain Axis and Its Role in Controlling Eating Behavior in Intestinal Inflammation

Malnutrition represents a major problem in the clinical management of the inflammatory bowel disease (IBD). Presently, our understanding of the cross-link between eating behavior and intestinal inflammation is still in its infancy. Crohn's disease patients with active disease exhibit strong hedonic desires for food and emotional eating patterns possibly to ameliorate feelings of low mood, anxiety, and depression. Impulsivity traits seen in IBD patients may predispose them to palatable food intake as an immediate reward rather than concerns for future health. The upregulation of enteroendocrine cells (EEC) peptide response to food intake has been described in ileal inflammation, which may lead to alterations in gut-brain signaling with implications for appetite and eating behavior. In summary, a complex interplay of gut peptides, psychological, cognitive factors, disease-related symptoms, and inflammatory burden may ultimately govern eating behavior in intestinal inflammation.

Appetite, the enteroendocrine system, gastrointestinal disease and obesity

The enteroendocrine system is located in the gastrointestinal (GI) tract, and makes up the largest endocrine system in the human body. Despite that, its roles and functions remain incompletely understood. Gut regulatory peptides are the main products of enteroendocrine cells, and play an integral role in the digestion and absorption of nutrients through their effect on intestinal secretions and gut motility. Several peptides, such as cholecystokinin, polypeptide YY and glucagon-like peptide-1, have traditionally been reported to suppress appetite following food intake, so-called satiety hormones. In this review, we propose that, in the healthy individual, this system to regulate appetite does not play a dominant role in normal food intake regulation, and that there is insufficient evidence to wholly link postprandial endogenous gut peptides with appetite-related behaviours. Instead, or additionally, top-down, hedonic drive and neurocognitive factors may have more of an impact on food intake. In GI disease however, supraphysiological levels of these hormones may have more of an impact on appetite regulation as well as contributing to other unpleasant abdominal symptoms, potentially as part of an innate response to injury. Further work is required to better understand the mechanisms involved in appetite control and unlock the therapeutic potential offered by the enteroendocrine system in GI disease and obesity.