The Effect of Ursodeoxycholic Acid on Small Intestinal Bacterial Overgrowth in Patients with Functional Dyspepsia: A Pilot Randomized Controlled Trial

H. pylori-Associated Gastritis, Gastritis after H. pylori Eradication and H. pylori-Negative Gastritis: Algorithm of Diagnosis and Treatment (Literature Review and Resolution of the Expert Panel of the Russian Gastroenterological Association)

Aim: to provide the basic points of the Expert Panel of the Russian Gastroenterological Association with discussion of measures to improve diagnostics, treatment and management of chronic gastritis patients.

Key points. In the Russian Federation in 2021 more than 30 million patients diagnosed with “Gastritis and duodenitis” were recorded (K29 in accordance with International Classification of Diseases-10). H. pylori incidence rate in the Russian population has reduced and presently is about 40 %. In chronic gastritis pattern H. pylori-associated gastritis has still dominated though gastritis percent after successful H. pylori eradication, reactive gastropathy (including reflux gastritis) and autoimmune gastritis, has increased. Endoscopic and histologic examinations serve as key diagnostic techniques that provide a means for assessing the ethiology of gastritis, topography and degree of atrophic changes, gastritis staging as per OLGA/OLGIM system that properly correlates with the risk of stomach cancer and determines endoscopic examination strategy. H. pylori eradication therapy of gastritis serves as an etiotropic treatment and makes it possible to prevent progression of atrophy and stomach cancer. Conventional triple therapy combined with bismuth tripotassium dicitrate allows for achieving optimal cure rates of H. pylori eradication. Addition of rebamipide to regimens of H. pylori eradication improves their efficiency. Rebamipide arrests symptoms of dyspepsia in the case of chronic gastritis and functional dyspepsia. The administration of rebamipide for chronic gastritis makes it possible to influence the syndrome of increased epithelial permeability and inflammation, which makes it advisable to study it as a means of preventing stomach cancer and the progression of atrophy in various types of chronic gastritis.

Conclusion. Members of the Expert Panel has approved the algorithm of diagnosis and treatment of H. pylori-associated gastritis, gastritis after H. pylori eradication and H. pylori-negative gastritis at the diagnostic stage in the case of initial presentation and long-term follow-up when needed.

In vitro fermentation characteristics of polysaccharides from coix seed and its effects on the gut microbiota

Coix seed polysaccharides had received increasing attention due to their diverse biological activities. In this study, a homogeneous polysaccharide (CSPW) was extracted and purified from coix seed. Furthermore, the saliva-gastrointestinal digestion and fecal fermentation behavior of CSPW were simulated in vitro. The results showed that CSPW was mainly composed of glucose. It cannot be degraded by the simulated salivary and intestinal digestive system, but can be degraded by the simulated gastric digestive system. After fermentation for 24 h, CSPW promoted the production of short-chain fatty acids (SCFAs), with acetic acid, propionic acid and n-butyric acid being the main metabolites. In addition, CSPW could significantly regulate the composition and microbial diversity of gut microbiota by increasing the relative abundance of beneficial bacteria, such as Limosilicactobacillus, Bifidobacterium and Collinsella. Finally, further analysis of functional prediction revealed that amino acid metabolism, nucleotide metabolism and carbohydrate metabolism were the most important pathways for CSPW to promote health. In summary, our findings suggested that CSPW could potentially be used as a good source of prebiotics because it can be used by gut microbiota to produce SCFAs and regulate the gut microbiota.

Potential therapeutic benefit of ursodeoxycholic acid in the management of non hepato-biliary upper gastrointestinal disorders

OBJECTIVES

To examine the potential therapeutic effects of ursodeoxycholic acid (UDCA) on diseases of the esophagus, stomach, and duodenum.

METHODS

A search was conducted using EBSCO, Medline, PubMed, Google Scholar and Web of Science as well as international guidelines using MESH terms for treatment of UDCA for diseases of the upper gastrointestinal disorders in adult humans without regard to publication language or date restrictions.

RESULTS

A total of 256 articles and 22 guidelines were initially identified, and 221 were excluded. Final revision of 13 articles and 22 guidelines confirmed that UDCA is found to have a cytoprotective role in Barret's esophagus within esophageal disorders, improves abdominal pain in functional dyspepsia, and does not alter Helicobacter pylori colonization or inflammation. Conflicting results are noted regarding the role of UDCA in the duodenum as chemopreventive treatment for familial adenomatous polyposis, with polyps regressing and their growth characteristics improving with low doses (10-25 mg/kg/day). On the contrary, no positive effect was noted upon the combination with Celecoxib and with doses of 1000-2000 mg or 20-30 mg/kg/d. Gastrointestinal side effects were predominantly reported. No side effects necessitated hospitalization or ICU admission.

CONCLUSION

Ursodeoxycholic acid has a limited therapeutic role in functional dyspepsia. There is promising evidence that it may serve as a chemopreventive for Familial adenomatous polyposis and Barret's esophagus, although further research is needed to confirm these findings.PROSPERO No.: CRD 42021267689.

Diagnosis by Microbial Culture, Breath Tests and Urinary Excretion Tests, and Treatments of Small Intestinal Bacterial Overgrowth

Small intestinal bacterial overgrowth (SIBO) is characterized as the increase in the number and/or alteration in the type of bacteria in the upper gastrointestinal tract and accompanies various bowel symptoms such as abdominal pain, bloating, gases, diarrhea, and so on. Clinically, SIBO is diagnosed by microbial culture in duodenum/jejunum fluid aspirates and/or the breath tests (BT) of hydrogen/methane gases after ingestion of carbohydrates such as glucose. The cultural analysis of aspirates is regarded as the golden standard for the diagnosis of SIBO; however, this is invasive and is not without risk to the patients. BT is an inexpensive and safe diagnostic test but lacks diagnostic sensitivity and specificity depending on the disease states of patients. Additionally, the urinary excretion tests are used for the SIBO diagnosis using chemically synthesized bile acid conjugates such as cholic acid (CA) conjugated with para-aminobenzoic acid (PABA-CA), ursodeoxycholic acid (UDCA) conjugated with PABA (PABA-UDCA) or conjugated with 5-aminosalicylic acid (5-ASA-UDCA). These conjugates are split by bacterial bile acid (cholylglycine) hydrolase. In the tests, the time courses of the urinary excretion rates of PABA or 5-ASA, including their metabolites, are determined as the measure of hydrolytic activity of intestinal bacteria. Although the number of clinical trials with this urinary excretion tests is small, results demonstrated the usefulness of bile acid conjugates as SIBO diagnostic substrates. PABA-UDCA disulfate, a single-pass type unabsorbable compound without the hydrolysis of conjugates, was likely to offer a simple and rapid method for the evaluation of SIBO without the use of radioisotopes or expensive special apparatus. Treatments of SIBO with antibiotics, probiotics, therapeutic diets, herbal medicines, and/or fecal microbiota transplantation are also reviewed.

Epithelial protective therapy in comorbid diseases. Practical Guidelines for Physicians

In 2021 the first multidisciplinary National Consensus on the pathophysiological and clinical aspects of Increased Epithelial Permeability Syndrome was published. The proposed guidelines are developed on the basis of this Consensus, by the same team of experts. Twenty-eight Practical Guidelines for Physicians statements were adopted by the Expert Council using the "delphic" method. Such main groups of epithelial protective drugs as proton pump inhibitors, bismuth drugs and probiotics are discussed in these Guidelines from the positions of evidence-based medicine. The clinical and pharmacological characteristics of such a universal epithelial protector as rebamipide, acting at the preepithelial, epithelial and subepithelial levels, throughout gastrointestinal tract, are presented in detail.

Characterization of gut microbial structural variations as determinants of human bile acid metabolism

Bile acids (BAs) facilitate intestinal fat absorption and act as important signaling molecules in host-gut microbiota crosstalk. BA-metabolizing pathways in the microbial community have been identified, but it remains largely unknown how the highly variable genomes of gut bacteria interact with host BA metabolism. We characterized 8,282 structural variants (SVs) of 55 bacterial species in the gut microbiomes of 1,437 individuals from two cohorts and performed a systematic association study with 39 plasma BA parameters. Both variations in SV-based continuous genetic makeup and discrete clusters showed correlations with BA metabolism. Metagenome-wide association analysis identified 809 replicable associations between bacterial SVs and BAs and SV regulators that mediate the effects of lifestyle factors on BA metabolism. This is the largest microbial genetic association analysis to demonstrate the impact of bacterial SVs on human BA composition, and it highlights the potential of targeting gut microbiota to regulate BA metabolism through lifestyle intervention.

Microbiome Metabolites and Thyroid Dysfunction

Thyroid diseases are common conditions that have a negative impact on the health of all populations. The literature sheds light on the differences in the composition of the intestinal microbiota in patients suffering from thyroid diseases compared to healthy individuals. The microbiome affects the proper functioning of the thyroid gland, and the existence of the gut–thyroid axis is discussed in the context of both thyroid diseases and intestinal dysbiosis. The purpose of this review is to describe associations between the microbiome and its metabolites and thyroid dysfunction. We try to explain the role of the microbiome in the metabolism of thyroid hormones and the impact of thyroid autoimmune diseases. In addition, we raise issues related to the influence of bacterial metabolites, such as short-chain fatty acids or secondary bile acids, in the functioning of the thyroid gland. Last but not least, we explored the interactions between the gut microbiota and therapeutics and supplements typically administered to patients with thyroid diseases.

Changes in oral flora of patients with functional dyspepsia

To explore the changes in oral flora in people with functional dyspepsia (FD). Unstimulated saliva was collected from 21 FD patients diagnosed according to the Rome IV criteria and from 12 healthy controls (HCs) for 16SrRNA sequencing. The pH of saliva samples and community periodontal index (CPI) were tested. The prevalence of small intestinal bacterial overgrowth (SIBO) was obtained by the methane-and hydrogen-based breath test. At the phylum level, FD patients had a higher relative abundance of Spirochaetes and a lower relative abundance of Fusobacteria, TM7 and Proteobacteria than HCs (p < 0.01). In the saliva, Kingella and Abiotrophia genus levels showed significant changes between the FD and HC groups (p < 0.01). Salivary species level marker Intermedia was significantly different between FD and HC groups (p < 0.01). The oral pH of FD patients was higher than that of HCs (p < 0.01). The mean CPI of the FD group was 1.52 and that of the HC group was 0.17 (p < 0.01). Moreover, 71.4% of the FD group was positive for SIBO. The oral flora of FD patients was different from that of HCs. Spirochaetes, Kingella, Abiotrophia, and Intermedia may be diagnostic indicators of FD.

Secondary bile acid ursodeoxycholic acid alters weight, the gut microbiota, and the bile acid pool in conventional mice

Ursodeoxycholic acid (commercially available as ursodiol) is a naturally occurring bile acid that is used to treat a variety of hepatic and gastrointestinal diseases. Ursodiol can modulate bile acid pools, which have the potential to alter the gut microbiota community structure. In turn, the gut microbial community can modulate bile acid pools, thus highlighting the interconnectedness of the gut microbiota-bile acid-host axis. Despite these interactions, it remains unclear if and how exogenously administered ursodiol shapes the gut microbial community structure and bile acid pool in conventional mice. This study aims to characterize how ursodiol alters the gastrointestinal ecosystem in conventional mice. C57BL/6J wildtype mice were given one of three doses of ursodiol (50, 150, or 450 mg/kg/day) by oral gavage for 21 days. Alterations in the gut microbiota and bile acids were examined including stool, ileal, and cecal content. Bile acids were also measured in serum. Significant weight loss was seen in mice treated with the low and high dose of ursodiol. Alterations in the microbial community structure and bile acid pool were seen in ileal and cecal content compared to pretreatment, and longitudinally in feces following the 21-day ursodiol treatment. In both ileal and cecal content, members of the Lachnospiraceae Family significantly contributed to the changes observed. This study is the first to provide a comprehensive view of how exogenously administered ursodiol shapes the healthy gastrointestinal ecosystem in conventional mice. Further studies to investigate how these changes in turn modify the host physiologic response are important.