Development of pancreatic acinar cell metaplasia after successful administration of omeprazole for 6 months in rats

Gastric development of pancreatic acinar cell metaplasia after Vonoprazan therapy in rats

BACKGROUND

Vonoprazan is a new acid-suppressing drug that received FDA approval in 2022. It reversibly inhibits gastric acid secretion by competing with the potassium ions on the luminal surface of the parietal cells (potassium-competitive acid blockers or P-CABs). Vonoprazan has been on the market for a short time and there are many clinical trials to support its clinical application. However, medical experience and comprehensive clinical data is still limited, especially on how and if, gastric histology is altered due to therapy.

METHODS

A 12-week experiment trial with 30 Wistar rats was to assess the presence of gastrointestinal morphologic abnormalities upon administration of omeprazole and vonoprazan. At six weeks of age, rats were randomly assigned to one of 5 groups: (1) saline as negative control group, (2) oral omeprazole (40 mg/kg), as positive control group, (3) oral omeprazole (40 mg/kg) for 4 weeks, proceeded by 8 weeks off omeprazole, (4) oral vonoprazan (4 mg/kg), as positive control group, and (5) oral vonoprazan (4 mg/kg) for 4 weeks, proceeded by 8 weeks off vonoprazan.

RESULTS

We identified non-inflammatory alterations characterized by parietal (oxyntic) cell loss and chief (zymogen) cell hyperplasia and replacement by pancreatic acinar cell metaplasia (PACM). No significant abnormalities were identified in any other tissues in the hepatobiliary and gastrointestinal tracts.

CONCLUSION

PACM has been reported in gastric mucosa, at the esophagogastric junction, at the distal esophagus, and in Barrett esophagus. However, the pathogenesis of this entity is still unclear. Whereas some authors have suggested that PACM is an acquired process others have raised the possibility of PACM being congenital in nature. Our results suggest that the duration of vonoprazan administration at a dose of 4 mg/kg plays an important role in the development of PACM.

Clinicopathological characteristics of pancreatic acinar cell metaplasia associated with Helicobacter pylori infection

Background

Pancreatic acinar cell metaplasia (PACM) has been rarely reported in the gastric mucosa. In the present study, we aimed to elucidate the clinical and pathological characteristics of PACM associated with Helicobacter pylori (H. pylori).

Method

5930 patients who underwent five- or two-point gastric biopsy according to the updated Sydney system (USS) by upper gastrointestinal endoscopy were enrolled. The patients were categorized into current H. pylori infection (CHI), post-H. pylori eradication (PHE), and non-H. pylori infection (NHI) groups according to the H. pylori infection status, and the frequency and location of PACM were compared. Additionally, a case–control study was performed to compare the USS scores between patients with CHI and PACM and those with CHI but not PACM.

Result

The frequencies of PACM were 0.49% (10/2039), 0.75% (25/3332), and 0% (0/559) in the CHI, PHE, and NHI groups, respectively. PACM was found in the greater curvature of the antrum in 33 of the 35 patients with PACM. Among the patients with CHI, the inflammation scores in the greater curvature of the antrum and the greater curvature of the corpus were lower in patients with PACM than in those without PACM.

Conclusion

Although rarely reported in the gastric mucosa, PACM was closely related to H. pylori infection, especially in the antrum, and was associated with relatively mild inflammation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12876-022-02338-2.

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.

Pharmacological Effects and Toxicogenetic Impacts of Omeprazole: Genomic Instability and Cancer

Omeprazole (OME) is commonly used to treat gastrointestinal disorders. However, long-term use of OME can increase the risk of gastric cancer. We aimed to characterize the pharmacological effects of OME and to correlate its adverse effects and toxicogenetic risks to the genomic instability mechanisms and cancer-based on database reports. Thus, a search (till Aug 2019) was made in the PubMed, Scopus, and ScienceDirect with relevant keywords. Based on the study objective, we included 80 clinical reports, forty-six in vitro, and 76 in vivo studies. While controversial, the findings suggest that long-term use of OME (5 to 40 mg/kg) can induce genomic instability. On the other hand, OME-mediated protective effects are well reported and related to proton pump blockade and anti-inflammatory activity through an increase in gastric flow, anti-inflammatory markers (COX-2 and interleukins) and antiapoptotic markers (caspases and BCL-2), glycoprotein expression, and neutrophil infiltration reduction. The reported adverse and toxic effects, especially in clinical studies, were atrophic gastritis, cobalamin deficiencies, homeostasis disorders, polyp development, hepatotoxicity, cytotoxicity, and genotoxicity. This study highlights that OME may induce genomic instability and increase the risk of certain types of cancer. Therefore, adequate precautions should be taken, especially in its long-term therapeutic strategies and self-medication practices.

Pancreatic Acinar Metaplasia in Distal Esophageal Biopsies Is Associated With Chronic Nonsteroidal Anti-inflammatory Drug Use

CONTEXT.—

The cause of pancreatic acinar metaplasia (PAM) at the distal esophagus/esophagogastric junction is still controversial. Whereas some authors believe it is congenital, others believe it is acquired because of inflammation of the gastric cardia, and more recently it was proposed to be due to chronic proton pump inhibitor use based on a study in rats.

OBJECTIVE.—

To determine whether there is correlation between chronic proton pump inhibitor use and PAM in humans. We also investigated the correlation between several clinical and pathologic factors and PAM.

DESIGN.—

Four hundred forty-four consecutive biopsies from the distal esophagus/esophagogastric junction were reviewed for the presence of PAM, which was then correlated with several clinical and pathologic findings.

RESULTS.—

Pancreatic acinar metaplasia was found in 71 patients (16%). Pancreatic acinar metaplasia was significantly associated with patient age younger than 51 years ( P < .001), chronic carditis ( P = .01), and chronic proton pump inhibitor use ( P = .008). Surprisingly, we also found significant association between PAM and chronic nonsteroidal anti-inflammatory drug use ( P < .001). These associations, including that with chronic nonsteroidal anti-inflammatory drug use, remained significant in multivariate analysis.

CONCLUSIONS.—

Our findings confirm the previous reports of significant association between PAM and chronic carditis and the findings from animal studies of association with chronic proton pump inhibitor use. The strong association with chronic nonsteroidal anti-inflammatory drug use has not been previously reported and warrants further studies.

Histopathological and Immunohistochemical Characterization of Methyl Eugenol-induced Nonneoplastic and Neoplastic Neuroendocrine Cell Lesions in Glandular Stomach of Rats

Methyl eugenol induces neuroendocrine (NE) cell hyperplasia and tumors in F344/N rat stomach. Detailed histopathological and immunohistochemical (IHC) characterization of these tumors has not been previously reported. The objective of this study was to fill that data gap. Archived slides and paraffin blocks were retrieved from the National Toxicology Program Archives. NE hyperplasias and tumors were stained with chromogranin A, synaptophysin, amylase, gastrin, H(+)/K(+) adenosine triphosphatase (ATPase), pepsinogen, somatostatin, and cytokeratin 18 (CK18) antibodies. Many of the rats had gastric mucosal atrophy, due to loss of chief and parietal cells. The hyperplasias and tumors were confined to fundic stomach, and females were more affected than the males. Hyperplasia of NE cells was not observed in the pyloric region. Approximately one-third of the females with malignant NE tumors had areas of pancreatic acinar differentiation. The rate of metastasis was 21%, with liver being the most common site of metastasis. Immunohistochemically, the hyperplasias and tumors stained consistently with chromogranin A and synaptophysin. Neoplastic cells were also positive for amylase and CK18 and negative for gastrin, somatostatin, H(+)/K(+) ATPase, and pepsinogen. Metastatic neoplasms histologically similar to the primary neoplasm stained positively for chromogranin A and synaptophysin. Based on the histopathological and IHC features, the neoplasms appear to arise from enterochromaffin-like cells.

Role of proton pump inhibitor on esophageal carcinogenesis and pancreatic acinar cell metaplasia development: an experimental in vivo study

Chronic gastro-duodenal reflux in the esophagus is a major risk for intestinal metaplasia and Barrett’s adenocarcinoma. A role for chronic use of proton pump inhibitor (PPI) in the increased incidence of esophageal adenocarcinoma in Western countries has been previously suggested. The aim of this work was to study the effect of chronic administration of omeprazole (a proton pump inhibitor) per os in a model of reflux induced esophageal carcinogenesis. One week after esophago-gastro-jejunostomy, 115 Sprague-Dawley rats were randomized to receive 10 mg/Kg per day of omeprazole or placebo, 5 days per week. The esophago-gastric specimens were collected 28±2 weeks after randomization and analyzed in a blinded fashion. Mortality and esophageal metaplasia rates did not differ between the two groups (p = 0.99 for mortality, p = 0.36 for intestinal metaplasia and p = 0.66 for multi-layered epithelium). Gastric pancreatic acinar cell metaplasia (PACM) was more frequently observed in PPI-treated rats (p = 0.003). Severe ulcer lesions significantly prevailed in the placebo group (p = 0.03). Locally invasive esophageal epithelial neoplasia were observed in 23/39 PPI-treated versus 14/42 placebo-animals (p = 0.03). In conclusion, chronic omeprazole treatment improved the healing of esophageal ulcerative lesions. Locally invasive neoplastic lesions and PACM prevailed among PPI-treated animals. However, neither an effect on the overall mortality nor on the incidence of pre-neoplastic lesions was observed in this work.

Pancreatic acinar cells--a normal finding at the gastroesophageal junction? Data from a prospective Central European multicenter study

Pancreatic acinar cells are a well-recognized finding at the gastroesophageal junction, but their histogenesis and biological significance are unclear. From the prospective Central European multicenter histoGERD trial, we recruited 1,071 individuals undergoing gastroscopy for various non-selected reasons. Biopsy material was systematically sampled from the gastroesophageal junction and from the stomach. The study aimed to assess the prevalence of pancreatic acinar cells and to relate their presence to various histologic and clinical features. Overall, pancreatic acinar cells were observed in 184 (17.2%) participants. Individuals diagnosed with pancreatic acinar cells were slightly younger than those without (median 50 vs. 53 years; p = 0.009). There was no association with patients' symptoms and/or complaints or with an endoscopic diagnosis of esophagitis or Barrett's esophagus. Regarding histology, pancreatic acinar cells were not associated with features of the squamous epithelium indicating reflux disease, such as basal cell hyperplasia, papillary elongation, dilation of intercellular spaces, and inflammatory cell number, but were associated with the presence of cardiac mucosa (p < 0.001), oxyntocardiac mucosa (p < 0.001), and intestinal metaplasia (p = 0.038), respectively. No association with Helicobacter pylori infection or diagnosis of gastritis was noted. In conclusion, pancreatic acinar cells are a common finding at the gastroesophageal junction, and no association with either reflux disease (histologically or endoscopically) or diagnosis of gastritis was observed. These data suggest a congenital rather than an acquired (metaplastic) origin of pancreatic acinar cells at the gastroesophageal junction. This questions the term "pancreatic acinar metaplasia" which is currently widely used for their diagnosis.

Is gastrectomy-induced high turnover of bone with hyperosteoidosis and increase of mineralization a typical osteomalacia?

Gastrectomy (GX) is thought to result in osteomalacia due to deficiencies in Vitamin D and Ca. Using a GX rat model, we showed that GX induced high turnover of bone with hyperosteoidosis, prominent increase of mineralization and increased mRNA expression of both osteoclast-derived tartrate-resistant acid phosphatase 5b and osteocalcin. The increased 1, 25(OH)2D3 level and unchanged PTH and calcitonin levels suggested that conventional bone and Ca metabolic pathways were not involved or changed in compensation. Thus, GX-induced bone pathology was different from a typical osteomalacia. Gene expression profiles through microarray analysis and data mining using Ingenuity Pathway Analysis indicated that 612 genes were up-regulated and 1,097 genes were down-regulated in the GX bone. These genes were related functionally to connective tissue development, skeletal and muscular system development and function, Ca signaling and the role of osteoblasts, osteoclasts and chondrocytes. Network analysis indicated 9 genes (Aldehyde dehydrogenase 1 family, member A1; Aquaporin 9; Interleukin 1 receptor accessory protein; Very low density lipoprotein receptor; Periostin, osteoblast specific factor; Aggrecan; Gremlin 1; Angiopoietin-like 4; Wingless-type MMTV integration site family, member 10B) were hubs connected with tissue development and immunological diseases. These results suggest that chronic systemic inflammation might underlie the GX-induced pathological changes in bone.

Pancreatic acinar metaplasia in the distal oesophagus and the gastric cardia: prevalence, predictors and relation to GORD

PURPOSE

The nature of pancreatic acinar metaplasia (PAM) in the gastro-oesophageal junction (GOJ) remains obscure. We aimed to estimate its prevalence and investigate into its risk factors in a population-based series of first-time endoscopy patients.

METHODS

We investigated consecutive patients, endoscoped for the first time, representing defined catchment area populations. Biopsies were taken immediately below the GOJ and from the distal oesophagus. Endoscopy room-based cross-sectional clinical data were supplemented with exposure data from 160 population controls. Associations, expressed as odds ratios (OR), were modelled with multivariable logistic regression. A subsample of 26 patients underwent oesophageal pH monitoring.

RESULTS

Among 644 patients (mean age 53 years, 43% men), PAM was found in 121 patients (19%), exclusively above the GOJ in 40 (6%), below GOJ in 67 (10%), and both above and below GOJ in 14 (2%). PAM exclusively above the GOJ and PAM exclusively below the GOJ were both borderline associated with age (2% increase in prevalence per year). PAM exclusively above the GOJ was significantly associated with female gender (OR 2.8, 95% CI 1.3-6.3) and presence of Helicobacter pylori immediately below the GOJ (OR 2.6, 95% CI 1.3-5.4). Out of 21 patients with Barrett's oesophagus (BO), 8 (38%) had PAM above the GOJ. The mean value for percentage time with oesophageal pH < 4.0 was 7.3% (95% CI 4.3-10.2%) among patients who had PAM above the GOJ (reference value 3.4%).

CONCLUSIONS

Pancreatic acinar metaplasia might be an age-dependent lesion, associated with H. pylori, female gender and gastro-oesophageal reflux if located above the GOJ.

Gastric acid reduction leads to an alteration in lower intestinal microflora

To clarify the alterations in lower intestinal microflora induced by gastric acid reduction, the dynamics of 12 major genera or groups of bacteria comprising the microflora in feces and colonic contents were examined by quantitative real-time PCR in proton pump inhibitor-treated rats and in asymptomatic human subjects with hypochlorhydria. In both rat and human experiments, most genera or groups of intestinal microflora (facultative and obligate anaerobes) proliferated by gastric acid reduction, and marked and significant increases in the Lactobacilli group and Veillonella, oropharyngeal bacteria, were observed. In rats, potent gastric acid inhibition led to a marked and significant increase of intestinal bacteria, including the Bacteroidesfragilis group, while Bifidobacterium, a beneficial bacterial species, remained at a constant level. These results strongly indicate that the gastric acid barrier not only controls the colonization and growth of oropharyngeal bacteria, but also regulates the population and composition of lower intestinal microflora.

Bravo capsule system optimizes intragastric pH monitoring over prolonged time: Effects of ghrelin on gastric acid and hormone secretion in the rat

AIM: To evaluate measurements of intragastric pH with the Bravo capsule system over a prolonged time.

METHODS: A Bravo capsule was placed inside the rat gastric body and pH was studied for periods up to five consecutive days. For comparison, a gastric fistula model was used. Effects of ghrelin and esomeprazole, with or without pentagastrin, on gastric pH were studied. In addition, effects of esomeprazole on plasma ghrelin, gastrin and somatostatin were analyzed.

RESULTS: All rats recovered after surgery. The average 24-h pH during free feeding was 2.3 ± 0.1 (n = 20) with a variation of 18% ± 6% over 5 d. Ghrelin, 2400 pmol/kg, t.i.d. increased pH from 1.7 ± 0.1 to 3.1 ± 0.3 (P < 0.01) as recorded with the Bravo system. After esomeprazole (1 mg/kg, 3 mg/kg and 5 mg/kg) there was a dose-dependent pH increase of maximally 3.4 ± 0.1, with day-to-day variation over the entire period of 8% ± 3%. The fistula and pH studies generated similar results. Acid inhibition with esomeprazole increased plasma ghrelin from 10 ± 2 pmol/L to 65 ± 26 pmol/L (P < 0.001), and somatostatin from 10 ± 2 pmol/L to 67 ± 18 pmol/L (P < 0.001).

CONCLUSION: pH measurements with the Bravo capsule are reliable, and comparable to those of the gastric fistula model. The Bravo system optimizes accurate intragastric pH monitoring over prolonged periods and allows both short- and long-term evaluation of effects of drugs and hormones.

Rebamipide contributes to reducing adverse effects of long-term administration of omeprazole in rats

Proton pump inhibitors (PPIs) have become of great importance for the treatment of peptic ulcer disease and gastroesophageal reflux disease. However, these drugs have several adverse effects, including worsening of corpus atrophic gastritis in patients with H. pylori infection, various histological changes including fundic gland-type polyps, inhibition of glycoprotein production, and hypergastrinemia. On the other hand, it has been reported that rebamipide, a gastroprotective drug, has the potential to increase mucous secretion and basically regulate physiological defensive functions aimed to maintain tissue integrity. In this study, we attempted to clarify whether rebamipide improves morphological changes and hypergastrinemia after administration of omeprazole (OPZ) for 1 year in rats. Eight-week-old male Wistar rats were used. Rats were divided into four groups according to diet as follows: 100 mg/kg body weight OPZ group, 100 mg/kg body weight OPZ and 30 mg/kg body weight rebamipide (OPZ + trebanipide group), 30 mg/kg body weight rebamipide, and normal diet (CRF-1). Morphological changes in gastric mucosa in all groups were studied using hematoxylin and eosin staining, periodic acid-Schiff staining, and immunohistochemical staining for alpha-amylase. Serum gastrin level and basal acid secretion were also examined. In the OPZ group, cystic degenerations with amorphous eosinophilic contents, decreased mucous secretion, decreased chief cells, and development of pancreatic acinar cell metaplasia were detected. However, in the OPZ+rebamipide group, these morphological changes were significantly milder than in the OPZ group. Serum gastrin level and basal acid secretion in the OPZ group increased significantly compared to those in the control group. But these factors in the OPZ+rebamipide group were almost normalized (similar to those of control animals). In conclusion, long-term OPZ treatment causes various morphological changes, hypergastrinemia, and basal acid hypersecretion. The present results suggest that rebamipide contributes to reducing these adverse effects caused by long-term OPZ treatment in rats.