Increased Faecalibacterium abundance is associated with clinical improvement in patients receiving rifaximin treatment.

Compositional and functional alterations of the gut microbiota are involved in the pathogenesis of several gastrointestinal diseases. Rifaximin is often used to induce disease remission due to its eubiotic effects on the gut microbiota. To investigate the correlation between changes in the gut microbiota composition and symptoms improvement in patients who present a clinical response to rifaximin treatment. Patients with ulcerative colitis (UC), Crohn's disease (CD), irritable bowel syndrome (IBS) and diverticular disease (DD) undergoing rifaximin treatment for clinical indication were enrolled in the study. Rifaximin was administered at the dose of 1,200 mg/day for 10 days. Faecal samples were collected at baseline and at the end of treatment; clinical improvement was assessed by Mayo score for UC, CD Activity Index (CDAI) for CD, IBS severity scoring system (IBS-SSS) for IBS and global symptomatic score (GSS) for DD. Twenty-five patients were included in the analysis and a clinical improvement was recorded for 10/25 (40%) of them. Microbial alpha diversity showed a slight increase in clinical responders (P=0.271), while it decreased in patients who did not improved (P=0.05). A significant post-treatment increase in Faecalibacterium abundance was observed in patients with a positive response (log2FC 1.959, P=0.042). Roseburia abundance decreased in both groups, whereas Ruminococcus decreased only in patients who clinically improved. Clinical improvement consequent to rifaximin treatment is associated with an increase in Faecalibacterium abundance. Achieving a positive shift in the gut microbiota composition seems a key event to obtain a clinical benefit from treatment.

Akkermansia muciniphila: key player in metabolic and gastrointestinal disorders.

OBJECTIVE: Gut microbiota has a key role in host metabolic regulation and immune response, and its dysbiosis represents one of the main causes of gastrointestinal diseases. In this scenario, Akkermansia muciniphila is a crucial player in keeping the integrity of the gastrointestinal tract. MATERIALS AND METHODS: This review focuses on the correlation between gut microbiota and intestinal homeostasis, primarily exploring A. muciniphila and its involvement in the development of metabolic disorders and gastrointestinal diseases. RESULTS: Akkermansia muciniphila belongs to the Verrucomicrobia phylum, and it colonizes the mucus layer in the gastrointestinal tract, representing 1 to 4% of the fecal microbiota. It stimulates mucosal microbial networks, and it improves intestinal barrier function, providing crucial host immunological responses. Several studies have demonstrated the possible involvement of A. muciniphila in the development of intestinal and metabolic disorders. Indeed, adipose and glucose metabolisms are influenced by A. muciniphila, and its levels inversely correlate to inflammatory conditions, such as inflammatory bowel disease, obesity, and diabetes. Conversely, its therapeutic administration decreases their development. CONCLUSIONS: A. muciniphila exerts a key role in the maintenance of intestinal health and in host metabolic modulation. Future studies could open new horizons towards its potential therapeutic applications in gastrointestinal and extra-intestinal diseases.

Intestinal permeability in physiological and pathological conditions: major determinants and assessment modalities.

Intestinal permeability is the property that allows solute and fluid exchange between intestinal lumen and intestinal mucosa. Many factors could have major impact on its regulation, including gut microbiota, mucus layer, epithelial cell integrity, epithelial junction, immune responses, intestinal vasculature, and intestinal motility. Any change among these factors could have an impact on intestinal homeostasis and gut permeability. Healthy condition is associated to normal intestinal permeability whereas several intestinal and extra intestinal disease, like inflammatory bowel disease, irritable bowel syndrome, non-alcoholic fatty liver disease among others, are associated to increased intestinal permeability. This review aims to synthesize determinants on intestinal permeability and to report methodologies useful to the measurement of intestinal permeability in clinical practice as well as in research settings.

Nutrition and IBD: Malnutrition and/or Sarcopenia? A Practical Guide.

Malnutrition is a major complication of inflammatory bowel disease (IBD). This mini review is focusing on main determinants of malnutrition in IBD, the most important components of malnutrition, including lean mass loss and sarcopenia, as an emerging problem. Each one of these components needs to be well considered in a correct nutritional evaluation of an IBD patient in order to build a correct multidisciplinary approach. The review is then focusing on possible instrumental and clinical armamentarium for the nutritional evaluation.

Efficacy and Mechanisms of Action of Fecal Microbiota Transplantation in Ulcerative Colitis: Pitfalls and Promises From a First Meta-Analysis.

BACKGROUND: Inflammatory bowel disease (IBD) is the results of a chronic inflammatory process deriving from disequilibrium between self-microbiota composition and immune response. METHODS: New evidence, coming from Clostridium difficile infection, clearly showed that active and powerful modulation of microbiota composition by fecal microbiota composition (FMT) is safe, easy to perform, and efficacious, opening new frontiers in gastrointestinal and extra-intestinal diseases. FMT has been proposed also for IBD as well as other non-gastrointestinal conditions related to intestinal microbiota dysfunctions, with good preliminary data. RESULTS: In this setting, ulcerative colitis (UC) represents one of the most robust potential indications for FMT after C difficile colitis. CONCLUSIONS: In the present review, we focus on FMT and its application on ulcerative colitis, clarifying mechanisms of actions and efficacy data, trough completion of a meta-analysis on available randomized, controlled trial data in UC. Because microbiota is so crucially involved in this topic, a short review of microbial alterations in UC will also be performed.

Gut Microbiota: A Key Modulator of Intestinal Healing in Inflammatory Bowel Disease.

Mucosal healing (MH) represents a crucial factor for maintaining gut homeostasis. Indeed, in inflammatory bowel disease, MH has become the standard therapeutical target, because it is associated with more effective disease control, more frequent steroid-free remission, lower rates of hospitalization and surgery, and improved quality of life. In this scenario, gut microbiota is a crucial player in modulating intestinal repair and regeneration process. It can act on the tumor necrosis factor-α production, modulation of reactive oxygen and nitrogen species, activity of matrix metalloproteinases and on many other mechanisms strictly involved in restoring gut health. In this review, we analyze and review the literature on the role of gut microbiota in sustaining mucosal injury and achieving MH.

The therapeutic management of gut barrier leaking: the emerging role for mucosal barrier protectors.

OBJECTIVE: Gut barrier is a functional unit organized as a multi-layer system and its multiple functions are crucial for maintaining gut homeostasis. Numerous scientific evidences showed a significant association between gut barrier leaking and gastro-intestinal/extra-intestinal diseases. MATERIALS AND METHODS: In this review we focus on the relationship between gut barrier leaking and human health. At the same time we speculate on the possible new role of gut barrier protectors in enhancing and restoring gut barrier physiology with the final goal of promoting gut health. RESULTS: The alteration of the equilibrium in gut barrier leads to the passage of the luminal contents to the underlying tissues and thus into the bloodstream, resulting in the activation of the immune response and in the induction of gut inflammation. This permeability alteration is the basis for the pathogenesis of many diseases, including infectious enterocolitis, inflammatory bowel diseases, irritable bowel syndrome, small intestinal bacterial overgrowth, celiac disease, hepatic fibrosis, food intolerances and also atopic manifestations. Many drugs or compounds used in the treatment of gastrointestinal disease are able to alter the permeability of the intestinal barrier. Recent data highlighted and introduced the possibility of using gelatin tannate, a mucosal barrier protector, for an innovative approach in the management of intestinal diseases, allowing an original therapeutic orientation with the aim of enhancing mucus barrier activity and restoring gut barrier. CONCLUSIONS: These results suggest how the mucus layer recovering, beside the gut microbiota modulation, exerted by gut barrier protectors could be a useful weapon to re-establish the physiological intestinal homeostasis after an acute and chronic injury.

Pre- and posttherapy assessment of intestinal soluble mediators in IBD: where we stand and future perspectives.

Inflammatory bowel disease (IBD) is a chronic inflammatory condition characterized by an abnormal immune response against food or bacterial antigens in genetically predisposed individuals. Several factors of innate and adaptive immune system take part in the inflammatory process, probably actively contributing in endoscopic and histological healing at molecular level. Although it is difficult to discriminate whether they are primary factors in determining these events or they are secondarily involved, it would be interesting to have a clear map of those factors in order to have a restricted number of potentially "good candidates" for mucosal healing. The present review will present a class of these factors and their modulation in course of therapy, starting from pathogenic studies involving several treatments associated with good clinical outcomes. This approach is meant to help in the difficult task of identifying "good candidates" for healing signatures, which could also be possible new therapeutic targets for clinical management of IBD patients.

Intestinal gas production and gastrointestinal symptoms: from pathogenesis to clinical implication.

Intestinal gases are the expression of metabolic activity of gut microbiota in the gut, particularly carbohydrates in the case of H2, CH4. Alterations in composition of gases and air handling, directly or upon challenge with food are relevant for GI and extra-GI diseases. Assessing gas composition in breath can be a very useful tool for clinic, but technical issues are crucial (breath sampling, storing and analyzing). Aim of the present review is to summarize the understanding of the importance of intestinal gases in gastro-intestinal physiology and patho-physiology. Practical considerations on how to collect samples and instruments available for the clinic have also been provided.

Specific 13C functional pathways as diagnostic targets in gastroenterology breath-tests: tricks for a correct interpretation.

Breath tests are non-invasive, non-radioactive, safe, simple and effective tests able to determine significant metabolic alterations due to specific diseases or lack of specific enzymes. Carbon isotope (13)C, the stable-non radioactive isotope of carbon, is the most used substrate in breath testing, in which (13)C/(12)C ratio is measured and expressed as a delta value, a differences between readings and a fixed standard. (13)C/(12)C ratio is measured with isotope ratio mass spectrometry or non-dispersive isotope-selective infrared spectrometer and generally there is a good agreement between these techniques in the isotope ratio estimation. (13)C/(12)C ratio can be expressed as static measurement (like delta over baseline in urea breath test) or as dynamic measurement as percent dose recovery, but more dosages are necessary. (13)C Breath-tests are involved in many fields of interest within gastroenterology, such as detection of Helicobacter pylori infection, study of gastric emptying, assessment of liver and exocrine pancreatic functions, determination of oro-caecal transit time, evaluation of absorption and to a lesser extend detection of bacterial overgrowth. The use of every single test in a clinical setting is vary depending on accuracy and substrate costs. This review is meant to present (13)C the meaning of (13)C/(12)C ratio and static and dynamic measure and, finally, the instruments dedicated to its use in gastroenterology. A brief presentation of (13)C breath tests in gastroenterology is also provided.

13C-octanoic acid breath test to study gastric emptying time.

Digestion is a complex process regulated by several factors. Among these, one of the most important is the time of gastric emptying. A delayed gastric emptying time can be caused by several factors and can generate considerable discomfort in humans. It ranges from mild to real debilitating disorders. Until now, different tests are suggested to study the gastric emptying time. The present review presents the mayor cause and the main symptoms linked to delayed gastric emptying and will focus on the (13)C-octanoid acid breath test, as a good candidate for studying solid gastric emptying time.

Tricks for interpreting and making a good report on hydrogen and 13C breath tests.

Breath tests (BT) represent a valid and non-invasive diagnostic tool in many gastroenterological disorders. Their wide diffusion is due to the low cost, simplicity and reproducibility and their common indications include diagnosis of carbohydrate malabsorption, Helicobacter pylori infection, small bowel bacterial overgrowth, gastric emptying time and orocaecal transit time. The review deals with key points on methodology, which would influence the correct interpretation of the test and on a correct report. While a clear guideline is available for lactose and glucose breath tests, no gold standard is available for Sorbitol, Fructose or other H2 BTs. Orocaecal transit time (OCTT) defined as time between assumption of 10 g lactulose and a peak > 10 ppm over the baseline value, is a well-defined breath test. The possible value of lactulose as a diagnostic test for the diagnosis of small bowel bacterial overgrowth is still under debate. Among (13)C breath test, the best and well characterized is represented by the urea breath test. Well-defined protocols are available also for other (13)C tests, although a reimbursement for these tests is still not available. Critical points in breath testing include the patient preparation for test, type of substrate utilized, reading machines, time between when the test is performed and when the test is processed. Another crucial point involves clinical conclusions coming from each test. For example, even if lactulose could be utilized for diagnosing small bowel bacterial overgrowth, this indication should be only secondary to orocaecal transit time, and added into notes, as clinical guidelines are still uncertain.