Citations

The overall objectives of this review are to summarize actionable biomarkers for organic etiology of lower functional gastrointestinal disorders (FGIDs) that lead to individualized treatment for their FGIDs and to assess the pipeline for novel approaches to the management of constipation, diarrhea, and chronic abdominal pain in lower FGIDs. The new approaches to therapy include ion exchangers/transporters for functional constipation (sodium-glucose cotransporter 1, Na+/H+ exchanger 3, and solute carrier family 26 member 3 inhibitors), bile acid modulators for constipation such as ileal bile acid transporter inhibitors and fibroblast growth factor 19 analog for functional constipation, and bile acid sequestrants or farnesoid X receptor agonists for functional diarrhea. Treatment for chronic abdominal pain remains an unmet need in patients with lower FGIDs, and promising novel approaches include delayed-release linaclotide, nonclassical opioid visceral analgesics, and selective cannabinoid receptor agonists. The role of probiotics, fecal microbial transplantation, and possible future microbiome therapies is discussed.

AbstractBackgroundNon‐ulcer dyspepsia (NUD) is a heterogeneous disorder, which is characterized by upper gastrointestinal symptoms and sensorimotor disturbances, including abnormal gastric emptying (GE) and increased intestinal chemosensitivity, and associated with greater plasma glucagon‐like peptide‐1 (GLP‐1) levels during duodenal lipid infusion. However, the relationship(s) between these disturbances and daily symptoms in NUD is variable. We hypothesize that abnormal GE and symptoms during a GE study and during duodenal lipid infusion are associated with the severity of daily symptoms and that GLP‐1 mediates symptoms during duodenal lipid infusion in NUD.MethodsGastric emptying of solids, symptoms during the GE study and duodenal lipid infusion, and daily gastrointestinal symptoms (2 week diary) were measured in 24 healthy controls and 40 NUD patients. During duodenal lipid infusion, participants received the GLP‐1 antagonist exendin 9‐39 or placebo.Key ResultsIn controls and patients, GE of solids was normal in 75% and 75%, delayed in 8% and 12.5%, or rapid in 17% and 12.5%, respectively. No controls but 26 patients (65%) had severe symptoms during the GE study. During lipid infusion, gastrointestinal symptoms were greater (P = .001) in patients and not affected by exendin. Symptoms during GE study and lipid infusion accounted for respectively 62% and 37% of variance in daily symptom severity.ConclusionsIn NUD, symptoms during a GE study and to a lesser extent during lipid infusion explain the variance in daily symptoms. Intestinal chemosensitivity is not reduced by GLP‐1 antagonist. Assessment of symptoms during a GE study may provide a useful biomarker for NUD in research and clinical practice.

Summary Background Due to the paucity of targeted therapy for irritable bowel syndrome (IBS), many patients turn to dietary modifications for symptom management. The combination of five subgroups of poorly absorbed and rapidly fermented carbohydrates—fructans, galacto‐oligosaccharides, lactose, excess fructose and polyols—are thought to trigger gastrointestinal symptoms and are referred to collectively as “FODMAPs”. Aims To examine the biological plausibility and mechanisms by which foods high in specific FODMAP subgroups cause symptoms, and to use this information to explore the possibility of targeting select dietary components to allow for a more personalised approach to dietary adjustment Methods Recent literature was analysed via search databases including Medline, PubMed and Scopus. Results Lactose, fructans and galacto‐oligosaccharides have strong biologic plausibility for symptom generation due to lack of hydrolases resulting in distention from osmosis and rapid fermentation. However, excess fructose and polyols may only cause symptoms in specific individuals when consumed in high doses, but this remains to be established. There is evidence to suggest that certain patient characteristics such as ethnicity may predict response to lactose, but differentiation of other subgroups is difficult prior to dietary manipulation. Conclusions While some clear mechanisms of action for symptom generation have been established, further research is needed to understand which patients will respond to specific FODMAP subgroup restriction. We suggest that clinicians consider in some patients a tailored, personalised “bottom‐up” approach to the low‐FODMAP diet, such as dietary restriction relevant to the patients’ ethnicity, symptom profile and usual dietary intake.

A reduction in intestinal barrier function is currently believed to play an important role in pathogenesis of many diseases, as it facilitates passage of injurious factors such as lipopolysaccharide, peptidoglycan, whole bacteria, and other toxins to traverse the barrier to damage the intestine or enter the portal circulation. Currently available evidence in animal models and in vitro systems has shown that certain dietary interventions can be used to reinforce the intestinal barrier to prevent the development of disease. The relevance of these studies to human health is unknown. Herein, we define the components of the intestinal barrier, review available modalities to assess its structure and function in humans, and review the available evidence in model systems or perturbations in humans that diet can be used to fortify intestinal barrier function. Acknowledging the technical challenges and the present gaps in knowledge, we provide a conceptual framework by which evidence could be developed to support the notion that diet can reinforce human intestinal barrier function to restore normal function and potentially reduce the risk for disease. Such evidence would provide information on the development of healthier diets and serve to provide a framework by which federal agencies such as the US Food and Drug Administration can evaluate evidence linking diet with normal human structure/function claims focused on reducing risk of disease in the general public.

The objectives of this review on ‘leaky gut’ for clinicians are to discuss the components of the intestinal barrier, the diverse measurements of intestinal permeability, their perturbation in non-inflammatory ‘stressed states’ and the impact of treatment with dietary factors. Information on ‘healthy’ or ‘leaky’ gut in the public domain requires confirmation before endorsing dietary exclusions, replacement with non-irritating foods (such as fermented foods) or use of supplements to repair the damage. The intestinal barrier includes surface mucus, epithelial layer and immune defences. Epithelial permeability results from increased paracellular transport, apoptosis or transcellular permeability. Barrier function can be tested in vivo using orally administered probe molecules or in vitro using mucosal biopsies from humans, exposing the colonic mucosa from rats or mice or cell layers to extracts of colonic mucosa or stool from human patients. Assessment of intestinal barrier requires measurements beyond the epithelial layer. ‘Stress’ disorders such as endurance exercise, non-steroidal anti-inflammatory drugs administration, pregnancy and surfactants (such as bile acids and dietary factors such as emulsifiers) increase permeability. Dietary factors can reverse intestinal leakiness and mucosal damage in the ‘stress’ disorders. Whereas inflammatory or ulcerating intestinal diseases result in leaky gut, no such disease can be cured by simply normalising intestinal barrier function. It is still unproven that restoring barrier function can ameliorate clinical manifestations in GI or systemic diseases. Clinicians should be aware of the potential of barrier dysfunction in GI diseases and of the barrier as a target for future therapy.

Objectives: To determine patient preference for treating opioid-induced constipation (OIC) using naloxegol or polyethylene glycol (PEG) 3350 in patients receiving opioids for noncancer pain. Methods: This crossover study included two 2-week active treatment periods, each preceded by a 1-week washout period (NCT03060512). Individuals with baseline Bowel Function Index scores ≥30 were randomized to 1 of 2 treatment sequences (naloxegol/PEG 3350 or PEG 3350/naloxegol). Patient preference (primary end point) was measured at the end of the second treatment period. Results: Of 276 patients randomized, 246 completed both treatment periods and reported preference (per protocol). Similar proportions of patients reported overall preference for naloxegol (50.4%) or PEG 3350 (48.0%; P = 0.92); 1.6% reported no preference. Medication characteristics influencing preference were similar for both treatments, except convenience and working quickly, which were strong influences of preference for higher proportions of patients preferring naloxegol (69.9% and 39.0%, respectively) vs those preferring PEG 3350 (29.9% and 27.4%, respectively). Patients aged <50 years or receiving laxatives within the previous 2 weeks generally preferred naloxegol. Changes from baseline in overall Bowel Function Index and Patient Global Impression of Change scores were similar between treatments, but analyses according to treatment preference revealed clinical improvement aligned with reported preference. Safety profiles were generally consistent with known medication profiles. Conclusions: Almost equal proportions of patients with OIC reported similar preference for daily naloxegol or PEG 3350 treatment, and their preference was generally supported by clinically relevant and measurable improvements in OIC symptoms.