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

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.

Management of Helicobacter pylori infection: Guidelines of the Italian Society of Gastroenterology (SIGE) and the Italian Society of Digestive Endoscopy (SIED)

Helicobacter pylori infection is very common and affects more than one-third of adults in Italy. Helicobacter pylori causes several gastro-duodenal diseases, such as gastritis, peptic ulcer and gastric malignancy, and extra-gastric diseases. The eradication of the bacteria is becoming complex to achieve due to increasing antimicrobial resistance. To address clinical questions related to the diagnosis and treatment of Helicobacter pylori infection, three working groups examined the following topics: (1) non-invasive and invasive diagnostic tests, (2) first-line treatment, and (3) rescue therapies for Helicobacter pylori infection. Recommendations are based on the best available evidence to help physicians manage Helicobacter pylori infection in Italy, and have been endorsed by the Italian Society of Gastroenterology and the Italian Society of Digestive Endoscopy.

Development of Pancreatic Acinar Cell Metaplasia During Gastric Repair in a Rat Duodenal Contents Reflux Model

BACKGROUND

We previously reported the development of pancreatic acinar cell metaplasia (PACM) in the glandular stomach of a duodenal contents reflux model (reflux model).

AIMS

We aimed to investigate the characteristics and histogenesis of PACM using a reflux model.

METHODS

A reflux model was created using 8-week-old male Wistar rats, which were killed up to 30 weeks postoperatively. Histological examination was performed to analyze the glandular stomach-jejunal anastomosis. Furthermore, electron microscopic images of PACM samples were compared with pancreatic and gastric glands removed from rats that had not undergone surgery. Immunostaining for α-amylase, HIK1083, TFF2, and Ki-67 was performed, and double fluorescent staining was carried out using antibodies against α-amylase and HIK1083, or α-amylase and TFF2.

RESULTS

In all reflux model rats, PACM was observed proximal to the glandular stomach-jejunal anastomosis, surrounded by pseudopyloric metaplasia. The number of chief cells was decreased in the deep part of the gland, where PACM occurred. Electron microscopy showed that PACM cells had greater numbers of rough endoplasmic reticulum tubules than chief cells, and exhibited pancreatic acinar cell morphology. Upon immunochemical staining, the regenerative foveolar epithelium and part of the pseudopyloric glands stained strongly positive for TFF2, whereas PACM cells were only weakly positive. Double fluorescent staining identified early lesions of PACM in the neck, which were double positive for α-amylase and TFF2, but negative for HIK1083.

CONCLUSIONS

PACM could be induced by duodenal contents reflux. PACM originates from stem cells located in the neck of oxyntic glands during gastric mucosal regeneration.

Evolutionary Analysis of Bile Acid-Conjugating Enzymes Reveals a Complex Duplication and Reciprocal Loss History

To fulfill their physiological functions, bile acids are conjugated with amino acids. In humans, conjugation is catalyzed by bile acid coenzyme A: amino acid N-acyltransferase (BAAT), an enzyme with a highly conserved catalytic triad in its active site. Interestingly, the conjugated amino acids are highly variable among mammals, with some species conjugating bile acids with both glycine and taurine, whereas others conjugate only taurine. The genetic origin of these bile acid conjugation differences is unknown. Here, we tested whether mutations in BAAT’s catalytic triad could explain bile acid conjugation differences. Our comparative analysis of 118 mammals first revealed that the ancestor of placental mammals and marsupials possessed two genes, BAAT and BAATP1, that arose by a tandem duplication. This duplication was followed by numerous gene losses, including BAATP1 in humans. Losses of either BAAT or BAATP1 largely happened in a reciprocal fashion, suggesting that a single conjugating enzyme is generally sufficient for mammals. In intact BAAT and BAATP1 genes, we observed multiple changes in the catalytic triad between Cys and Ser residues. Surprisingly, although mutagenesis experiments with the human enzyme have shown that replacing Cys for Ser greatly diminishes the glycine-conjugating ability, across mammals we found that this residue provides little power in predicting the experimentally measured amino acids that are conjugated with bile acids. This suggests that the mechanism of BAAT’s enzymatic function is incompletely understood, despite relying on a classic catalytic triad. More generally, our evolutionary analysis indicates that results of mutagenesis experiments may not easily be extrapolatable to other species.

Mean platelet volume and red cell distribution width as potential new biomarkers in children with gastroesophageal reflux disease

The aim of this study was to calculate the corrected rate of reflux in children with gastroesophageal reflux (GER)-like complaints by 24-hour pH monitoring and esophagogastroduodenoscopy (EGD), and to determine the utility of mean platelet volume (MPV) and red cell distribution width (RDW) as diagnostic biomarkers of GER disease (GERD) in children. The subjects in this prospective study were 109 children, 6 to 18 years old. Of them, 74 subjects were with GER symptoms and 35 healthy controls. The subjects were divided into three groups: those who underwent 24-hour pH monitoring (Group 1), those who underwent EGD together with pH monitoring (Group 2), and the healthy controls (Group 3). The results of pH monitoring and EGD and hematological parameters with controls were compared between Groups 1 and 2. In Groups 1 and 2, the overall rate of reflux was 40%, of esophagitis was 27.8%, and of Helicobacter pylori infection was 31.2%. The MPV and RDW cut-offs in subjects with reflux were ≤ 8.97 (sensitivity 89%, specificity 89%) and ≤ 12.78 (sensitivity 80%, specificity 97%), with an area under the Receiver Operating Characteristic (ROC) curve ± standard error (AUC ± SE) = 0.917 ± 0.027 (P < 0.001) and AUC ± SE = 0.866 ± 0.036 (P < 0.001), respectively. The endoscopic procedures are not practical due to being invasive and expensive. However, hemogram is a simple test which can be performed in an outpatient clinic. MPV and RDW calculated in hemogram could be easy, cost-effective, and high sensitive new biomarkers that can be used in children with GERD.

Etiology, pathogenesis, diagnosis and treatment of bile reflux gastritis

Bile reflux gastritis is a common disease of the digestive system, whose clinical characteristics are abdominal pain, abdominal distention and nausea and vomiting, affecting the quality of life of patients seriously. However, the etiology and pathogenesis of bile reflux gastritis are still unclear, which may be related to gastrointestinal surgery, gallbladder disease, Helicobacter pylori infection, psychological factors, etc. There are many diagnostic methods, but a consensus on diagnosis is still lacking. Most of the current treatments are symptomatic treatments, but the overall efficacy is poor. This article reviews the etiology, pathogenesis, diagnosis and treatment of bile reflux gastritis, with an aim to provide a reference for further research of this disease.

Helicobacter pylori infection and gastroesophageal reflux in children

Some studies suggest that Helicobacter pylori (H. pylori) infection would be a protective factor for the gastroesophageal reflux. The aim of this study was to explore this fact. A group of 72 children, admitted in a pediatric gastroenterology regional center in Northeast Romania, diagnosed with gastroesophageal reflux by 24-hour continuous esophageal pH monitoring (results were interpreted using the Boix-Ochoa score), underwent upper endoscopy with gastric biopsy to detect the presence of H. pylori by the rapid urease testing and for bacteriological and histologic examination. 19 children (26.39%) had H. pylori infection, while 53 (73.61%) did not. The grade of esophagitis was classified according to the Los Angeles classification system. Out of 47 children with esophagitis A, 16 (34.04%) had H. pylori infection, while out of the 25 children with esophagitis B, only 3 (12%) had H. pylori infection, with statistic significance (χ² = 54.69, P << 0.05, 95% confidence interval [CI]). Regarding the value of the Boix-Ochoa score, it appears that the presence of the H. pylori determines lower pH-metry scores (F = 8.13, P = 0.0015, 95% CI). The presence of the H. pylori was not an important factor in the gastroesophageal reflux. On the other hand its relationship with esophagitis appears to be inverse ratio. The fact that the H. pylori presence is statistically greater in the grade A esophagitis could confirm the hypothesis that the bacteria would slow down the development of the esophagitis.

Association between Pattern of Gastritis and Gastroesophageal Reflux Disease in Patients with Helicobacter Pylori Infection

BACKGROUND

Reflux disease is a common gastrointestinal problem. The association between reflux disease and gastritis pattern is controversial. AIM: To determine the association between reflux disease and gastritis pattern in patients with Helicobacter pylori (H. pylori) infection.

METHODS

470 patients with dyspepsia and reflux disease were enrolled in this study. The inclusion criteria were willing to participate in the study, age over 40 years, and having the criteria of ROME III for at least 3 months. Patients with history of H. pylori eradication therapy during the 3 months before the study, a history of gastric surgery, and gastric cancer were excluded. All of the participants underwent upper endoscopy and two biopsy samples were taken from antrum, body, and fundal areas.

RESULTS

H. pylori infection rate was 367 (78.1%) with mean age of 59.8 ± 11.4 years. Of them 131 patients (35.7%) were male. Reflux disease was detected in 273 (74.4%) patients. 216 (58.9%) and 102 (27.8%) patients had non-erosive reflux disease (NERD) and gastroesophageal reflux disease (GERD), respectively. Corpus predominant and antral predominant gastritis were seen in 72 (19.6%) and 129 (35.2%) patients, respectively. Antral gastritis was significantly associated with GERD (p<0.01). In regression analysis, antral predominant gastritis had a significant association with GERD (OR=1.92; 95%CI: 1.22- 3.12). The same result was observed in mild to moderate antral and greater curvature gastritis (OR= 1.26; 95%CI: 0.25-6.40 and OR= 3.0; 95%CI: 0.63-14.17, respectively).

CONCLUSION

According to these finding ,we could suggest that the pattern of gastritis could be associated with reflux disease and GERD.

Role of ion transporters in the bile acid-induced esophageal injury

Barrett's esophagus (BE) is considered to be the most severe complication of gastro-esophageal reflux disease (GERD), in which the prolonged, repetitive episodes of combined acidic and biliary reflux result in the replacement of the squamous esophageal lining by columnar epithelium. Therefore, the acid-extruding mechanisms of esophageal epithelial cells (EECs) may play an important role in the defense. Our aim was to identify the presence of acid/base transporters on EECs and to investigate the effect of bile acids on their expressions and functions. Human EEC lines (CP-A and CP-D) were acutely exposed to bile acid cocktail (BAC) and the changes in intracellular pH (pHi) and Ca(2+) concentration ([Ca(2+)]i) were measured by microfluorometry. mRNA and protein expression of ion transporters was investigated by RT-PCR, Western blot, and immunohistochemistry. We have identified the presence of a Na(+)/H(+) exchanger (NHE), Na(+)/HCO3 (-) cotransporter (NBC), and a Cl(-)-dependent HCO3 (-) secretory mechanism in CP-A and CP-D cells. Acute administration of BAC stimulated HCO3 (-) secretion in both cell lines and the NHE activity in CP-D cells by an inositol triphosphate-dependent calcium release. Chronic administration of BAC to EECs increased the expression of ion transporters compared with nontreated cells. A similar expression pattern was observed in biopsy samples from BE compared with normal epithelium. We have shown that acute administration of bile acids differently alters ion transport mechanisms of EECs, whereas chronic exposure to bile acids increases the expression of acid/base transporters. We speculate that these adaptive processes of EECs represent an important mucosal defense against the bile acid-induced epithelial injury.

Proton pump inhibitors and helicobacter pylori-associated pathogenesis

The fact that long-term use of proton pump inhibitors (PPIs) aggravates corpus atrophic gastritis in patients with Helicobacter pylori infection has been proven clinically and experimentally. Corpus atrophic gastritis is a known risk factor for gastric cancer. Therefore, gastric neoplasia might be associated with the long-term use of PPIs. One of the causes of worsening corpus atrophic gastritis, leading to the development of adenocarcinoma, might be bacterial overgrowth under conditions of hypochlorhydria. The production of potentially carcinogenic N-nitrosocompounds by nitrosating organisms under conditions of hypochlorhydria might be associated with carcinogenesis. Interactions between bile acids, pH, and H. pylori might also contribute to carcinogenicity, especially in patients with gastro-esophageal reflux disease (GERD). The concentration of soluble bile acids, which have bactericidal or chemorepellent properties toward H. pylori, in gastric contents is considerably higher in patients undergoing continuous PPI therapy than in healthy individuals with normal acid production. Under these circumstances, H. pylori might colonize the stomach body rather than the pyloric antrum. Hypergastrinemia induced by PPI administration might promote the development of gastric cancer. Because the main cause of corpus atrophic gastritis is H. pylori infection, and not PPI administration, H. pylori infection should be eradicated before starting long-term PPI therapy.

Functional anatomy and physiology of gastric secretion

PURPOSE OF REVIEW

This review summarizes the past year's literature regarding the neuroendocrine and intracellular regulation of gastric acid secretion, discussing both basic and clinical aspects.

RECENT FINDINGS

Gastric acid facilitates the digestion of protein as well as the absorption of iron, calcium, vitamin B12, and certain medications. High acidity kills ingested microorganisms and limits bacterial overgrowth, enteric infection, and possibly spontaneous bacterial peritonitis. The main stimulants of acid secretion are gastrin, released from antral gastrin cells; histamine, released from oxyntic enterochromaffin-like cells; and acetylcholine, released from antral and oxyntic intramural neurons. Ghrelin and coffee also stimulate acid secretion whereas somatostatin, cholecystokinin, glucagon-like peptide-1, and atrial natriuretic peptide inhibit acid secretion. Although 95% of parietal cells are contained within the oxyntic mucosa (fundus and body), 50% of human antral glands contain parietal cells. Proton pump inhibitors are considered well tolerated drugs, but concerns have been raised regarding dysbiosis, atrophic gastritis, hypergastrinemia, hypomagnesemia, and enteritis/colitis.

SUMMARY

Our understanding of the functional anatomy and physiology of gastric secretion continues to advance. Such knowledge is crucial for improved management of acid-peptic disorders, prevention and management of neoplasia, and the development of novel medications.

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.