H. pylori in the pathogenesis of duodenal ulcer: interaction between duodenal acid load, bile, and H. pylori

Exploration of gastric carcinogenesis from the relationship between bile acids and intestinal metaplasia and intragastric microorganisms (H. pylori and non-H. pylori)

Gastric cancer (GC) is a prevalent form of cancer, with Helicobacter pylori (H. pylori) infection being the most common risk factor. Recent studies have highlighted the role of long-term irritation of the gastric mucosa caused by bile reflux in the development of cancer. Bile acids (BAs), which are a significant component in bile reflux, have the potential to promote gastric carcinogenesis through various mechanisms. These mechanisms include the induction of intestinal metaplasia (IM), inhibition of H. pylori activity, modification of H. pylori colonization, and alteration of the abundance and composition of microorganisms in the stomach. Defining the mechanism of bile acid-induced gastric carcinogenesis could potentially be an effective approach to prevent GC. Hence, this paper aims to review the mechanism of bile acid-induced IM, the association between BAs and H. pylori infection as well as microorganisms in the stomach, and the correlation between BAs and gastric carcinogenesis. The ultimate goal is to elucidate the role of BAs in the development of GC.

Bile reflux alters the profile of the gastric mucosa microbiota

Background

Bile reflux can cause inflammation, gastric mucosa atrophy, and diseases such as stomach cancer. Alkaline bile flowing back into the stomach affects the intragastric environment and can alter the gastric bacterial community. We sought to identify the characteristics of the stomach mucosal microbiota in patients with bile reflux.

Methods

Gastric mucosal samples were collected from 52 and 40 chronic gastritis patients with and without bile reflux, respectively. The bacterial profile was determined using 16S rRNA gene analysis.

Results

In the absence of H. pylori infection, the richness (based on the Sobs and Chao1 indices; P <0.05) and diversity (based on Shannon indices; P <0.05) of gastric mucosa microbiota were higher in patients with bile reflux patients than in those without. There was a marked difference in the microbiota structure between patients with and without bile reflux (ANOSIM, R=0.058, P=0.011). While the genera, Comamonas, Halomonas, Bradymonas, Pseudomonas, Marinobacter, Arthrobacter, and Shewanella were enriched in patients with bile reflux, the genera, Haemophilus, Porphyromonas, and Subdoligranulum, were enriched in those without bile reflux.

Conclusion

Our results demonstrate that bile reflux significantly alters the composition of the gastric microbiota.

Pyloric Incompetence Associated with Helicobactor pylori Infection and Correlated to the Severity of Atrophic Gastritis

Duodenogastric reflux (DGR) causes bile reflux gastritis (BRG) and may develop into gastric cancer. DGR is classified as primary in non-operated stomachs or secondary to surgical intervention. Primary DGR and Helicobacter pylori (H. pylori) infection are reportedly related. However, the mechanism is not fully understood. This study aimed to elucidate the relationship between H. pylori infection and pyloric incompetence in a non-operated stomach. A total of 502 non-operated participants who underwent an upper intestinal endoscopy were prospectively enrolled. Endoscopic findings (EAC, endoscopic atrophy classification; nodular gastritis; xanthoma; fundic gland polyp; and incompetence of pylorus), sex, age, gastrin, pepsinogen (PG) I and PG II levels were evaluated. PG I/PG II ratio, anti-H. pylori-Ab positivity, and atrophic gastritis status were significantly different between the normal and incompetent pylori (p = 0.043, <0.001, and 0.001, respectively). Open-type atrophic gastritis was significantly higher in the incompetent pylori. Incompetence of the pylorus and EAC were moderately correlated (Cramer’s V = 0.25). Multivariate analysis revealed that the presence of anti-H. pylori-Ab was the only independent factor associated with the incompetence of the pylorus, with an adjusted odds ratio of 2.70 (95% CI: 1.47−4.94, p = 0.001). In conclusion, pyloric incompetence was associated with H. pylori infection and moderately correlated to the severity of atrophic gastritis in non-operated stomachs.

Analysis of Risk Factors and Establishment of a Prediction Model for Endoscopic Primary Bile Reflux: A Single-Center Retrospective Study

Background: Endoscopic primary bile reflux is one of the main diagnostic criteria for bile reflux gastritis (BRG). Presently, the risk factors and prediction models of endoscopic primary bile reflux (EPBR) in gastropathy patients who cannot or will not undergo endoscopy due to contraindications are not clear. Thus, this study aimed to evaluate the risk factors of EPBR and to establish and verify a prediction model.

Methods: A series of 844 patients (564 subjects with EPBR and 280 control subjects) were retrospectively selected for this study and divided into a training set (n = 591) and a validation set (n = 253) according to the usual ratio of 70:30% for the subsequent internal validation of the logistic regression model for EPBR. Fifteen parameters that might affect the occurrence of EPBR were collected. Subsequently, univariate and stepwise logistic regression analyses were introduced to reveal the risk factors and the multivariate prediction model. An R package was dedicated to the corresponding internal validation of the EPBR model.

Results: The univariate analysis showed that gender, age, smoking, Helicobacter pylori (H. pylori) infection status, metabolic syndrome (MS), non-steroidal anti-inflammatory drugs (NSAIDs) use history, and previous medical histories of chronic liver diseases, cholelithiasis, and erosive gastritis were statistically significant between the two groups (P < 0.05). Multivariate regression described that being a male [OR (95%confidence interval (CI)) = 2.29 (1.50–3.50), P < 0.001], age≥45 years old [OR (95% CI) = 4.24 (2.59–6.96), P < 0.001], H. pylori infection status [OR (95% CI) = 2.34 (1.37–4.01), P = 0.002], MS [OR (95% CI) = 3.14 (1.77–5.54), P < 0.001], NSAIDs use history [OR (95% CI) = 1.87 (1.03–3.40), P = 0.04], cholelithiasis history [OR (95% CI) = 3.95 (2.18–7.18), P < 0.001] and erosive gastritis history [OR (95% CI) = 6.77 (3.73–12.29), P < 0.001] were the risk factors for the occurrence of EPBR. Based on the results of these risk factors, an EPBR prediction model with an adequate calibration and excellent discrimination was established [area under the curve (AUC): 0.839, 95% CI = 0.806–0.872].

Conclusions: Being a male, age ≥ 45 years old, H. pylori infection, histories of MS, NSAIDs use, cholelithiasis, and erosive gastritis appear to be the risk factors for EPBR, and our favorable prediction model might be an option for the prediction of EPBR.

The relationship between gastric cancer, its precancerous lesions and bile reflux: A retrospective study

OBJECTIVE

To evaluate the relationship between gastric cancer (GC) and precancerous lesions and bile reflux.

METHODS

Medical records of 30 465 participants who underwent gastroscopy between January and December 2018 in our center were reviewed. Their age, sex, time of endoscopy, endoscopic/histologic diagnosis and grade of bile reflux were recorded. The participants were further divided into the chronic gastritis group (n = 27 807), a precancerous lesion group (n = 1943) and a GC group (n = 715). The χ² tests and hierarchical analyses were performed.

RESULTS

Patients aged 18-27 years had a higher bile reflux rate than those aged 28-37 and 68-75 years (P < 0.001), while it did not differ between patients aged <50 years and those over 50 years (P = 0.639). It was lower in men than in women (P < 0.001). The bile reflux rate did not differ in terms of months, seasons and half of the year (all P > 0.05), but differed between morning and afternoon when they underwent the endoscopy (P = 0.000). There was an interrelationship between the severity of gastric mucosal disease and bile reflux grade (r = 0.171). After excluding the effects of sex, age and time of endoscopy on bile reflux, bile reflux rate in chronic gastritis and precancerous lesions was lower than in gastric cancer (P < 0.01).

CONCLUSIONS

Bile reflux may be a risk factor for gastric cancer and precancerous lesions. A high grade of bile reflux may be associated with the progression of gastric mucosal diseases.

Increased Risk of Peptic Ulcers Following a Cholecystectomy for Gallstones

This retrospective cohort study examined the relationship between a cholecystectomy and the subsequent risk of peptic ulcers using a population-based database. Data for this study were retrieved from the Taiwan Longitudinal Health Insurance Database 2005. This study included 5209 patients who had undergone a cholecystectomy for gallstones and 15,627 sex- and age-matched comparison patients. We individually tracked each patient for a 5-year period to identify those who subsequently received a diagnosis of peptic ulcers. We found that of the 20,836 sampled patients, 2033 patients (9.76%) received a diagnosis of peptic ulcers during the 5-year follow-up period: 674 from the study group (12.94% of the patients who underwent a cholecystectomy) and 1359 from the comparison group (8.70% of the comparison patients). The stratified Cox proportional hazard regressions showed that the adjusted hazard ratio (HR) for peptic ulcers during the 5-year follow-up period was 1.48 (95% CI = 1.34~1.64) for patients who underwent a cholecystectomy than comparison patients. Furthermore, the adjusted HRs of gastric ulcers and duodenal ulcers during the 5-year follow-up period were 1.70 and 1.71, respectively, for patients who underwent a cholecystectomy compared to comparison patients. This study demonstrated a relationship between a cholecystectomy and a subsequent diagnosis of peptic ulcers.

Two distinct etiologies of gastric cardia adenocarcinoma: interactions among pH, Helicobacter pylori, and bile acids

Gastric cancer can be classified as cardia and non-cardia subtypes according to the anatomic site. Although the gastric cancer incidence has decreased steadily in several countries over the past 50 years, the incidence of cardia cancers and esophageal adenocarcinoma (EAC) continue to increase. The etiological factors involved in the development of both cardia cancers and EACs are associated with high animal fat intake, which causes severe obesity. Central obesity plays roles in cardiac-type mucosa lengthening and partial hiatus hernia development. There are two distinct etiologies of cardia cancer subtypes: one associated with gastroesophageal reflux (GER), which predominantly occurs in patients without Helicobacter pylori (H. pylori) infection and resembles EAC, and the other associated with H. pylori atrophic gastritis, which resembles non-cardia cancer. The former can be developed in the environment of high volume duodenal content reflux, including bile acids and a higher acid production in H. pylori-negative patients. N-nitroso compounds, which are generated from the refluxate that includes a large volume of bile acids and are stabilized in the stomach (which has high levels of gastric acid), play a pivotal role in this carcinogenesis. The latter can be associated with the changing colonization of H. pylori from the distal to the proximal stomach with atrophic gastritis because a high concentration of soluble bile acids in an environment of low acid production is likely to act as a bactericide or chemorepellent for H. pylori in the distal stomach. The manuscript introduces new insights in causative factors of adenocarcinoma of the cardia about the role of bile acids in gastro-esophageal refluxate based upon robust evidences supporting interactions among pH, H. pylori, and bile acids.

Potential mechanism of corpus-predominant gastritis after PPI therapy in Helicobacter pylori-positive patients with GERD

The long-term use of proton pump inhibitors (PPIs) exacerbates corpus atrophic gastritis in patients with Helicobacter pylori (H. pylori) infection. To identify a potential mechanism for this change, we discuss interactions between pH, bile acids, and H. pylori. Duodenogastric reflux, which includes bile, occurs in healthy individuals, and bile reflux is increased in patients with gastroesophageal reflux disease (GERD). Diluted human plasma and bile acids have been found to be significant chemoattractants and chemorepellents, respectively, for the bacillus H. pylori. Although only taurine conjugates, with a pKa of 1.8-1.9, are soluble in an acidic environment, glycine conjugates, with a pKa of 4.3-5.2, as well as taurine-conjugated bile acids are soluble in the presence of PPI therapy. Thus, the soluble bile acid concentrations in the gastric contents of patients with GERD after continuous PPI therapy are considerably higher than that in those with intact acid production. In the distal stomach, the high concentration of soluble bile acids is likely to act as a bactericide or chemorepellent for H. pylori. In contrast, the mucous layer in the proximal stomach has an optimal bile concentration that forms chemotactic gradients with plasma components required to direct H. pylori to the epithelial surface. H. pylori may then colonize in the stomach body rather than in the pyloric antrum, which may explain the occurrence of corpus-predominant gastritis after PPI therapy in H. pylori-positive patients with GERD.

Bile acids and bicarbonate inversely regulate intracellular cyclic di-GMP in Vibrio cholerae

Vibrio cholerae is a Gram-negative bacterium that persists in aquatic reservoirs and causes the diarrheal disease cholera upon entry into a human host. V. cholerae employs the second messenger molecule 3',5'-cyclic diguanylic acid (c-di-GMP) to transition between these two distinct lifestyles. c-di-GMP is synthesized by diguanylate cyclase (DGC) enzymes and hydrolyzed by phosphodiesterase (PDE) enzymes. Bacteria typically encode many different DGCs and PDEs within their genomes. Presumably, each enzyme senses and responds to cognate environmental cues by alteration of enzymatic activity. c-di-GMP represses the expression of virulence factors in V. cholerae, and it is predicted that the intracellular concentration of c-di-GMP is low during infection. Contrary to this model, we found that bile acids, a prevalent constituent of the human proximal small intestine, increase intracellular c-di-GMP in V. cholerae. We identified four c-di-GMP turnover enzymes that contribute to increased intracellular c-di-GMP in the presence of bile acids, and deletion of these enzymes eliminates the bile induction of c-di-GMP and biofilm formation. Furthermore, this bile-mediated increase in c-di-GMP is quenched by bicarbonate, the intestinal pH buffer secreted by intestinal epithelial cells. Our results lead us to propose that V. cholerae senses distinct microenvironments within the small intestine using bile and bicarbonate as chemical cues and responds by modulating the intracellular concentration of c-di-GMP.

Restoring psychology's role in peptic ulcer

This paper reviews the history of the transition from the belief that gastrointestinal ulcers are caused primarily by psychological factors to the current state of belief that they are caused primarily by infection and argues that neither is fully accurate. We argue that psychological factors play a significant role as predisposing to vulnerability, modulating of precipitation, and sustaining of gastric ulceration. We review data that challenge the assumption of a simple infectious disease model and adduce recent preclinical data that confirm the predisposing, modulatory, and sustaining roles for psychological factors. We note that others, too, are now challenging the adequacy of the contemporary simple bacterial infection model. We hope to replace the competition between psychology and medicine with cooperation in understanding and treating patients suffering gastric ulceration and ulcer.

A Case of Small Bowel Ulcer Associated with Helicobacter pylori

The etiology of peptic ulcer disease in children may be primary, associated with Helicobacter pylori infection, or secondary, relied on underlying disease. Ulcerative lesions by H. pylori are mainly distributed in the duodenal bulb and they are rare below the ampulla of Vater because H. pylori growth is inhibited by bile juice. In this reason, there are only some restrictive reports presented small bowel ulcer associated H. pylori. We found multiple small bowel ulcerative lesions associated with H. pylori in an 11-year-old girl without any systemic disease while performing esophagogastroenteroscopy to the level of the proximal jejunum for differentiating bezoar. The abdominal pain improved after the patient was administered H. pylori eradication therapy. Because a small bowel ulcer associated with H. pylori has rarely been reported, we report it here with literature review.

Helicobacter pylori protein response to human bile stress

The ability of Helicobacter pylori to tolerate bile is likely to be important for its colonization and survival in the gastrointestinal tract of humans. As bile can be acidified after reflux into the low pH of the human stomach, the inhibitory effect of fresh human bile with normal appearance on H. pylori before and after acidification was tested first. The results showed that acidification of bile attenuated its inhibitory activity towards H. pylori. Next, the protein profiles of H. pylori under human bile and acidified bile stress were obtained by two-dimensional electrophoresis. Protein spots with differential expression were identified using tandem matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The results showed that the changes in proteomic profiles under bile and acidified bile stress were similar when compared with that of normal H. pylori. Expression of 28 proteins was found to be modulated, with the majority being induced during bile or acidified bile exposure. These proteins included molecular chaperones, proteins involved in iron storage, chemotaxis protein, enzymes related to energy metabolism and flagellar protein. These results indicate that H. pylori responds to bile and acidified bile stress through multiple mechanisms involving many signalling pathways.

Helicobacter pylori in areas of gastric metaplasia in the gallbladder and isolation of H. pylori DNA from gallstones

AIMS

To assess if the areas of gastric metaplasia in the gallbladder are colonised by Helicobacter pylori and to conduct a molecular study of gallstones for presence of H. pylori DNA.

METHODS

Sections from 111 gallbladders with evidence of gastric metaplasia on H&E and Alcian blue-periodic acid-Schiff (pH 2.5) stain were stained with Loeffler's methylene blue and Warthin Starry stain for demonstration of H. pylori. Presence of H. pylori was confirmed by immunohistochemistry. Formalin fixed mucosal tissues and gallstones from 11 cases showing heavy colonisation were subjected to molecular analysis.

RESULTS

Helicobacter pylori was present in 50 of 111 (45%) sections with gastric metaplasia. Areas adjacent to gastric metaplasia in gallbladder showed acute inflammation (6%) and lymphoid follicle formation in 58% of cases with H. pylori that were significantly higher than those seen in sections without H. pylori. In molecular study, 8 of 11 gallstones showed 16S rDNA. Amplification of material from one stone showed positivity for atpA, efp, mutY, ppa, trpC, UreI and vacA genes. Phylogenetic affiliation study of the isolates indicated that H. pylori sequence from the gallstones clustered with Indian strains of H. pylori. No considerable difference was observed in phylogenetic affiliations of eight stones studied.

CONCLUSION

H. pylori colonises areas of gastric metaplasia in gallbladder producing histological changes similar to those seen in gastric mucosa. Isolation of H. pylori DNA from gallstones further support its presence in the gallbladder.

Bile acids in gastric fluids from llamas and alpacas with and without ulcers

To investigate the relationship between duodenogastric reflux and ulceration, gastric fluid was collected from the 1st (n = 26) and 3rd (n = 45) gastric compartments of llamas and alpacas during postmortem examination. Gastric fluids were analyzed for the presence of bile acids. Additionally, the 3rd compartment was examined grossly for the presence of erosions or ulcers, and the intestines were examined for evidence of fluid distention. Detectable bile acids were found in the 3rd compartment fluid of 1 of 28 camelids without ulcers, 7 of 14 camelids with ulcers, and 3 of 3 camelids with intestinal distention. Third compartment bile content was significantly higher in camelids with ulcers (median = 2.9 micromol/L) or intestinal distention (median = 371.5 micromol/L) than those with neither (median = 0 micromol/L). Bile acids were detected in the 1st gastric compartment in only 2 camelids. These findings suggest a reflux of duodenal contents, including bile acids, into the 3rd compartment in camelids with ulcers, similar to what is seen in camelids with poor intestinal emptying. Whether bile reflux was the cause of the ulcers or occurred after or concurrent to their development remains unknown.

Culturing Helicobacter pylori from clinical specimens: review of microbiologic methods

Helicobacter pylori is probably the most common chronic bacterial infection of humankind, and is usually acquired first in childhood. Microbiologic culture of H. pylori is the "gold standard" for diagnosis in a patient with suspected infection. Although not currently recommended for routine use, culture allows testing for susceptibility to antimicrobials, especially in populations with a high prevalence of drug resistance. Gastric biopsies are the specimens most commonly used to culture H. pylori, but stool, vomitus, saliva, and dental plaque offer opportunities. This review examines the current methods used to culture H. pylori from biologic specimens and suggests useful hints to enhance its recovery rate.

Pathogenesis and therapy of gastric and duodenal ulcer disease

Despite the decreasing frequency of Helicobacter pylori-induced peptic ulcers, peptic ulcer disease remains a major clinical problem partly because nonsteroidal anti-inflammatory drug ulcers have increased in frequency. The reduction in nonsteroidal anti-inflammatory drug ulcers by use of selective cyclooxygenase-2 inhibitors will not eliminate the problem because of increased use of aspirin for cardiovascular prophylaxis. This article reviews current concepts of peptic ulcer pathogenesis and therapy according to ulcer etiology; discusses potential interactions between etiologies; and considers the therapy for H pylori infection including the effects of antimicrobial resistance, and the role of bismuth quadruple therapy or furazolidone salvage therapy.

Psychosocial factors in peptic ulcer and inflammatory bowel disease

Over the past decade, while gastroenterologists' interest in mind-body interactions in organic disorders dwindled, stronger evidence has linked psychosocial factors with the incidence and recurrence of peptic ulcer and with the course of inflammatory bowel disease. Psychological-behavioral approaches to treatment continue to be disappointing. Psychosocial factors may affect ulcer by increasing duodenal acid load, altering local circulation or motility, intensifying Helicobacter pylori infection, stimulating corticosteroid secretion, and affecting health risk behaviors; possible mechanisms for inflammatory bowel disease include immune deregulation, gut permeability changes, and poor medication adherence. Both belong to the growing category of diseases thought to have an infectious component: for peptic ulcer the bacterium Helicobacter pylori, for inflammatory bowel disease an exaggerated immune response to gut bacteria. Peptic ulcer and inflammatory bowel disease, which present unique interactions among psychological, immunologic, endocrine, infectious, and behavioral factors, are splendid paradigms of the biopsychosocial model.

Characterization of a culture method to recover Helicobacter pylori from the feces of infected patients

BACKGROUND

Helicobacter pylori is difficult to culture from stool. Multiple efforts from multiple laboratories have been unsuccessful, and the optimal conditions to recover H. pylori from stool are still not known. Recovery of H. pylori from feces of infected individuals is important for the performance of molecular epidemiological investigations, especially in children, where their symptoms do not warrant endoscopy to recover the organism.

METHODS

Fresh fecal specimens (noncathartic) were obtained from 19 known H. pylori-infected patients and were processed to recover the organism. Fresh fecal specimens (noncathartic) were also obtained from three known H. pylori-negative individuals (controls) to determine whether H. pylori could be isolated from stools seeded with known concentrations of the organism. Treatment of the fecal suspensions with cholestyramine, a basic anion exchange resin that binds bile acids, was used in an attempt to enhance recovery of H. pylori by sequestering bile acids that are inhibitory to H. pylori growth. H. pylori was identified based on colony morphology, cell morphology, Gram's stain, biochemical reactions, and polymerase chain reaction for two H. pylori genes.

RESULTS

Among 19 patients, H. pylori was cultured at least once from 3 and three times from 2 (5 of 19). Feces that were seeded with H. pylori and obtained from three H. pylori-negative volunteer controls yielded positive recovery in all instances.

CONCLUSION

We have confirmed that it is possible to culture H. pylori from human stool, but the procedure for optimal recovery has still not been defined.