The Cutting Edge Research of Functional Gastrointestinal Disorders in Japan: Review on JGA Core Symposium 2018-2020

Isolation of mucosa-associated microbiota dysbiosis in the ascending colon in hepatitis C virus post-sustained virologic response cirrhotic patients

Background

Achieving sustained virologic response (SVR) in patients infected with hepatitis C virus (HCV) reduces all-cause mortality. However, the mechanisms and risk factors for liver fibrosis and portal hypertension post-SVR remain incompletely understood. In the gut-liver axis, mucosa-associated microbiota (MAM) substantially influence immune and metabolic functions, displaying spatial heterogeneity at the anatomical intestinal site. We analyzed MAM composition and function to isolate the locoregional MAM involved in chronic liver disease progression in HCV post-SVR patients.

Methods

We collected MAM samples from three intestinal sites (terminal ileum, ascending colon, and sigmoid colon) via brushing during colonoscopy in 23 HCV post-SVR patients and 25 individuals without liver disease (controls). The 16S rRNA of bacterial DNA in specimens collected with a brush and in feces was sequenced. The molecular expression of intestinal tissues and hepatic tissues were evaluated by quantitative real-time PCR.

Results

In the post-SVR group, the microbial β-diversity of MAM, especially in the ascending colon, differed from the control group and was associated with liver fibrosis progression. In PICRUSt analysis, MAM in the ascending colon in the liver cirrhosis (LC) group showed compromised functions associated with the intestinal barrier and bile acid production, and FGF19 expression was markedly decreased in the terminal ileum biopsy tissue in the LC group. At the genus level, six short-chain fatty acid (SCFA)-producing bacterial genera, Blautia, Alistipes, Roseburia, Agathobaculum, Dorea, and Pseudoflavonifractor were reduced in the ascending colon of post-SVR LC patients.

Conclusion

In patients of HCV post-SVR, we identified the association between the degree of liver fibrosis and dysbiosis of mucosa-associated SCFA-producing bacterial genera that may be related to intestinal barrier and bile acid production in the ascending colon.

The Association between Laughter and Functional Dyspepsia in a Young Japanese Population

The potential health benefits of laughter are recognized in relation to several chronic diseases. However, no study has yet investigated the association between laughter and functional dyspepsia (FD). The purpose of this study was to investigate this issue in a young Japanese population.

METHODS

This study was conducted on 8923 Japanese university students. Information on the frequency of laughter and types of laughter-inducing situations, digestive symptoms (Rome III criteria) were obtained through a self-administered, web-based questionnaire.

RESULTS

The percentage of respondents who laughed out loud almost every day was 64.3%. On the other hand, 1.8% of the subjects reported that they rarely laughed. No association was found between the total frequency of laughter and FD. Laughing while talking with family and friends almost every day was significantly inversely associated with FD (adjusted odds ratio (OR): 0.47 (95% confidence interval (CI): 0.28-0.81); p for trend was 0.003). On the other hand, laughing while watching TV or videos and laughing while looking at comics or magazines independently showed a positive correlation with FD (TV or videos: adjusted OR, 1-5 times a week: 1.74 (95% CI: 1.16-2.60); comics or magazines: adjusted OR, 1-5 times a week: 1.78 (95% CI: 1.08-2.81)).

CONCLUSION

In this young Japanese population, no association between laughter frequency and FD was observed although laughing while talking with friends and family was independently and inversely associated with FD.

Potential Roles of Enterochromaffin Cells in Early Life Stress-Induced Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is one of the most common functional gastrointestinal disorders, also known as disorders of the gut–brain interaction; however, the pathophysiology of IBS remains unclear. Early life stress (ELS) is one of the most common risk factors for IBS development. However, the molecular mechanisms by which ELS induces IBS remain unclear. Enterochromaffin cells (ECs), as a prime source of peripheral serotonin (5-HT), play a pivotal role in intestinal motility, secretion, proinflammatory and anti-inflammatory effects, and visceral sensation. ECs can sense various stimuli and microbiota metabolites such as short-chain fatty acids (SCFAs) and secondary bile acids. ECs can sense the luminal environment and transmit signals to the brain via exogenous vagal and spinal nerve afferents. Increasing evidence suggests that an ECs-5-HT signaling imbalance plays a crucial role in the pathogenesis of ELS-induced IBS. A recent study using a maternal separation (MS) animal model mimicking ELS showed that MS induced expansion of intestinal stem cells and their differentiation toward secretory lineages, including ECs, leading to ECs hyperplasia, increased 5-HT production, and visceral hyperalgesia. This suggests that ELS-induced IBS may be associated with increased ECs-5-HT signaling. Furthermore, ECs are closely related to corticotropin-releasing hormone, mast cells, neuron growth factor, bile acids, and SCFAs, all of which contribute to the pathogenesis of IBS. Collectively, ECs may play a role in the pathogenesis of ELS-induced IBS. Therefore, this review summarizes the physiological function of ECs and focuses on their potential role in the pathogenesis of IBS based on clinical and pre-clinical evidence.

Lifestyle- and comorbidity-related factors for the prescription of proton pump inhibitors after Helicobacter pylori eradication in Japan

Background and Aim

The aim of the present study was to examine the lifestyle‐ and comorbidity‐related determinant factors of the prescription of proton pump inhibitors (PPIs) for patients in whom Helicobacter pylori has been eradicated, and to evaluate the relationship between PPI prescription and the severity of endoscopic esophagitis.

Methods

This retrospective study included patients who underwent H. pylori eradication from May 2012 to September 2016 at Saiseikai Karatsu Hospital. All patients received upper gastrointestinal endoscopy before H. pylori eradication. Patients with open peptic ulcers and/or malignant diseases were excluded, and a final total of 389 patients were evaluated. Medical records were reviewed to determine the prescription of PPIs after H. pylori eradication, lifestyle‐related factors, and comorbidities. Lifestyle‐related factors were confirmed by a questionnaire.

Results

PPIs were administered to 124 of 389 patients (31.9%). The only lifestyle‐related risk factor for the prescription of PPIs after H. pylori eradication was older age (P < 0.01). Hypertension increased the prescription of PPIs (P = 0.034). The prescription of PPIs was not influenced by the presence of grade A esophagitis, whereas the PPI prescription rate was significantly increased in patients with grades B/C/D endoscopic esophagitis (P < 0.01). The grade of chronic gastritis before H. pylori eradication had no effect on the prescription of PPIs.

Conclusion

The lifestyle‐ and comorbidity‐related risk factors for the prescription of PPIs after H. pylori eradication were older age and hypertension, while mild endoscopic esophagitis had no influence on PPI prescription.

Pancreatic Fibrosis (Early Chronic Pancreatitis) as Emerging Diagnosis in Structural Causes of Dyspepsia: Evidence from Endoscopic Ultrasonography and Shear Wave Elastography

A new concept for the diagnosis and management of non-functional dyspepsia in guidelines was lacking in the past decade. Medical advancement has proven pancreatic fibrosis (essential image evidence of early chronic pancreatitis) to be a cause of dyspepsia and related to pancreatic exocrine dysfunction. This study aimed to analyze the clinical picture, biomarker, and percentage of pancreatic fibrosis in the dyspeptic population. A total of 141 consecutive patients were retrospectively enrolled. They were diagnosed with peptic ulcer disease, 9.2% (n = 13); pancreatic fibrosis, 17% (n = 24); pure Helicobacter pylori infection, 19.9% (n = 28); functional dyspepsia, 53.2% (n = 75); and chronic pancreatitis, 0.7% (n = 1). Among those with pancreatic fibrosis, (n = 24), 11 were diagnosed on the basis of a pancreatic acoustic radiation force impulse exceeding 1.4 m/s, and the remaining 13 were diagnosed with early chronic pancreatitis with at least three of the Japanese endoscopic ultrasonography criteria. The anatomic distribution of parenchymal criteria of early chronic pancreatitis was head, 53%; body, 38%; and tail, 9%. There were 17 cases (71%, 17/24) without Helicobacter pylori and whose dyspepsia improved after pancreatic enzyme replacement with a ratio of 82.3% (14/17). Of the 141 cases, 19 received gastric emptying scintigraphy and Western blot analysis of chromogranin-A in duodenal mucosa. Delayed gastric emptying was more common in functional dyspepsia and chromogranin-A was expressed more in pancreatic fibrosis. In conclusion, pancreatic fibrosis (including early chronic pancreatitis) outnumbered peptic ulcer disease in the dyspeptic population and pancreatic enzyme therapy was effective for 82% of cases. In early chronic pancreatitis, pancreatic fibrosis is dominant in the head location, and duodenum mucosa chromogranin-A is a potential biomarker with increased expression in an age-matched manner.

The Ketogenic Diet Reduces the Harmful Effects of Stress on Gut Mitochondrial Biogenesis in a Rat Model of Irritable Bowel Syndrome

Functional alterations in irritable bowel syndrome have been associated with defects in bioenergetics and the mitochondrial network. Effects of high fat, adequate-protein, low carbohydrate ketogenic diet (KD) involve oxidative stress, inflammation, mitochondrial function, and biogenesis. The aim was to evaluate the KD efficacy in reducing the effects of stress on gut mitochondria. Newborn Wistar rats were exposed to maternal deprivation to induce IBS in adulthood. Intestinal inflammation (COX-2 and TRL-4); cellular redox status (SOD 1, SOD 2, PrxIII, mtDNA oxidatively modified purines); mitochondrial biogenesis (PPAR-γ, PGC-1α, COX-4, mtDNA content); and autophagy (Beclin-1, LC3 II) were evaluated in the colon of exposed rats fed with KD (IBD-KD) or standard diet (IBS-Std), and in unexposed controls (Ctrl). IBS-Std rats showed dysfunctional mitochondrial biogenesis (PPAR-γ, PGC-1α, COX-4, and mtDNA contents lower than in Ctrl) associated with inflammation and increased oxidative stress (higher levels of COX-2 and TLR-4, SOD 1, SOD 2, PrxIII, and oxidatively modified purines than in Ctrl). Loss of autophagy efficacy appeared from reduced levels of Beclin-1 and LC3 II. Feeding of animals with KD elicited compensatory mechanisms able to reduce inflammation, oxidative stress, restore mitochondrial function, and baseline autophagy, possibly via the upregulation of the PPAR-γ/PGC-1α axis.

Gut Microbiota Comparison Between Intestinal Contents and Mucosa in Mice With Repeated Stress-Related Diarrhea Provides Novel Insight

Repeated stress-related diarrhea is a kind of functional bowel disorders (FBDs) that are mainly stemming from dysregulation of the microbiota–gut–brain axis mediated by a complex interplay of 5-hydroxytryptophan (5-HT). Intestinal content and intestinal mucosa microbiota belong to two different community systems, and the role of the two microbiota community systems in repeated stress-related diarrhea remains largely unknown. In order to ascertain the difference in composition and the potential function between intestinal content and intestinal mucosa microbiota response on repeated stress-related diarrhea, we collected intestinal contents and mucosa of mice with repeated stress-related diarrhea for 16S rRNA PacBio SMRT gene full-length sequencing, and with the digital modeling method of bacterial species abundance, the correlations among the two microbiota community systems and serum 5-HT concentration were analyzed. We found that the microbiotal composition differences both in intestinal contents and mucosa were consistent throughout all the phylogenetic ranks, with an increasing level of resolution. Compared with intestinal content microbiota, the diversity and composition of microbiota colonized in intestinal mucosa are more sensitive to repeated stress-related diarrhea. The PICRUSt2 of metagenomic function analysis found that repeated stress-related diarrhea is more likely to perturb the intestinal mucosa microbiota metagenomic functions involved in the neural response. We further found that the mucosal microbiota-based relative abundance model was more predictive on serum 5-HT concentration with the methods of machine-learning model established and multivariate dimensionality reduction (R² = 0.876). These findings suggest that the intestinal mucosa microbiota might serve as a novel potential prediction model for the serum 5-HT concentration involvement in the repeated stress-related diarrhea, in addition to focusing on its mechanism in the gastrointestinal dysfunction.