Reviews & Analysis

The gastrointestinal hormones ghrelin and motilin are released during hunger to stimulate appetite and interdigestive movement of the stomach, respectively. Ghrelin and motilin receptor agonists also increase gastric emptying of meals and emerging data shows previously unknown effects on nausea and constipation. In this Review, Sanger and Furness describe the complex interactions of ghrelin and motilin with their receptors and the pathways influencing gastrointestinal functions. Finally, they describe the potential of receptor agonists to treat various gastrointestinal disorders.

A gluten-free diet is the mainstay of treatment for patients with coeliac disease, and is still the only treatment available. In this Review, the authors provide practical insights into implementation of a gluten-free diet as a guide for clinicians, including challenges for patients, considerations for special populations, adherence and follow-up.

A global consensus report on Helicobacter pylori gastritis has been developed. Topics discussed include whether dyspepsia caused by H. pylori infection is separate from functional dyspepsia or not, the evaluation method for H. pylori-induced gastritis, eradication therapy for H. pylori gastritis to prevent gastric carcinogenesis and management after H. pylori eradication.

Early detection of colorectal lesions is the cornerstone of cancer prevention. Intravenous administration of a novel fluorescent peptide probe now enables the screening of the whole colorectal area using near-infrared fluorescence colonoscopy, an approach that was documented as safe, well-tolerated and specific in its detection of colorectal polyps.

Leaks are the most common post-operative complication of bariatric surgery; a procedure which is on the rise owing to the increased prevalence of obesity. Pierre Eisendrath and Jacques Deviere discuss the use of endoscopy as a therapeutic approach to resolving these complications, showing that it is a valid alternative to avoid additional surgical procedures.

A small subset of patients with coeliac disease do not respond to therapy with a gluten-free diet. These individuals are considered to have refractory coeliac disease (RCD), of which there are two known subtypes. In this Review, the authors provide an overview of RCD discussing the pathogenesis, diagnosis and management of this condition.

HBV persists by depositing covalently closed circular DNA (cccDNA) into the nucleus of infected host cells. HBV X protein (HBx) is a crucial determinant for regulating HBV activity, but the molecular details have not been fully understood. A new role for HBx in regulating cccDNA transcription has now been identified.

With a growing population of children developing NAFLD, our understanding of the similarities and differences between paediatric, adolescent and adult NAFLD is getting ever more important. In this Review, Mencin, Loomba and Lavine outline the clinically relevant differences in epidemiology, pathology, pathophysiology and treatment of paediatric NAFLD and discuss the transition of care into adulthood.

Many autoimmune diseases are known to occur alongside coeliac disease and, in some instances, patients see improvements in both if coeliac disease is diagnosed and treated. Shared genetic traits have been identified between coeliac disease and many of these forms of autoimmunity. In this Review, an overview is presented of the genetic and immunological features of coeliac disease, its overlap with other autoimmune diseases and implications for screening strategies.

IBS is the most common brain–gut disorder and a major cause of chronic abdominal pain. Here, Mayer and colleagues describe the key components of the gut–brain–microbiota axis in IBS and present a systems-based view of how these components interact to integrate the central, peripheral and behavioural IBS-related alterations.

Modulation of the gut microbiota is one of the promising tools to tackle obesity. Chang and colleagues have recently shown that an extract of the mushroom Ganoderma lucidum, a traditional remedy in Asia, can reduce obesity in mice by modulating the gut microbiota, thereby exerting a prebiotic effect.

The landscape of treatment for IBD changed dramatically with the introduction of biologic agents, of which several are now in use for this condition. Here, the authors provide practical insights into the use of biologic agents in IBD, discussing issues such as comparative effectiveness, safety, immunogenicity, cost and patient preference.

Measurements of liver copper content are considered the gold standard for diagnosis of Wilson disease. New evidence shows that a reduction of the diagnostic threshold indicative for Wilson disease potentially improves diagnostic accuracy.

Upper gastrointestinal cancer is often missed during examinations and survival outcomes are still poor among patients in the Western world. As discussed in this Perspectives, following the Japanese example, an improved gastroscopy technique, advanced training for endoscopists and optimized screening procedures for risk stratification will be necessary to elicit a change in clinical practice and improve diagnosis and treatment.

Coeliac disease is common, but remains under-diagnosed, partly because it can present with extraintestinal symptoms that do not immediately enable an accurate diagnosis of the underlying disease. In this Review, Leffler and colleagues discuss the most common extraintestinal manifestations, including dermatitis herpetiformis, gluten ataxia, anaemia, osteoporosis and others, to raise additional awareness among clinicians.

The role of the gut microbiota in brain development and behaviour is emerging. New research demonstrates that maturation and activation of microglia are regulated by the gut microbiota, providing more evidence for the link between the microbiota and brain health.

Coeliac disease is an immune-mediated enteropathy induced by gluten. Generation of gluten-specific CD4⁺ T cells is necessary but not sufficient to induce overt disease. Now, epithelial stress has been proposed as a distinct factor that synergizes with the anti-gluten adaptive immune response to induce intraepithelial lymphocyte activation and tissue damage.

Disease risk and treatment response is determined by an individual's complex history of genetic and environmental interactions. Personalized health care therefore requires an in-depth understanding of patient biology that can now be measured using '-omics' technologies. In this Review, different metabolic profiling methods and applications are described that might introduce a new dimension in personalized patient care in gastroenterology and hepatology.

Striking placebo responses seen in randomized clinical trials have generated an interest in investigating this phenomenon in gastroenterology. Sigrid Elsenbruch and Paul Enck discuss general aspects of the placebo response relating to gastroenterology and aspects that are unique to gastrointestinal disease. This Review provides a fascinating insight into placebo research and how this phenomenon could be exploited in the future for better patient care.

Restrictive transfusion strategy saves blood and is safe in most clinical settings, including gastrointestinal bleeding. However, generalizability of a restrictive transfusion approach in acute gastrointestinal bleeding remains controversial as it often affects elderly patients with major cardiovascular comorbidity who have been excluded from existing trials.