Chronic hypergastrinemia: causes and consequences

Constitutive programmed death ligand 1 expression protects gastric G-cells from Helicobacter pylori-induced inflammation

INTRODUCTION

Gastric intestinal metaplasia (GIM) is a premalignant lesion, highly associated with Helicobacter pylori infection. Previous studies have shown that H. pylori is able to induce the expression of programmed death ligand 1 (PD-L1), an inhibitory immune modulator, in gastric cells. Our aim was to investigate whether tissues from GIM patients may exploit PD-L1 expression upon H. pylori infection to evade immunosurveillance.

METHODS

Immunohistochemistry was performed for PD-L1 and enteroendocrine markers somatostatin and gastrin on samples derived from a cohort of patients with known GIM, both before and after H. pylori eradication. To determine the identity of any observed PD-L1-positive cells, we performed multiplex immunofluorescent staining and analysis of single-cell sequencing data.

RESULTS

GIM tissue was rarely positive for PD-L1. In normal glands from GIM patients, PD-L1 was mainly expressed by gastrin-positive G-cells. While the D-cell and G-cell compartments were both diminished 2-fold (p = .015 and p = .01, respectively) during H. pylori infection in the normal antral tissue of GIM patients, they were restored 1 year after eradication. The total number of PD-L1-positive cells was not affected by H. pylori, but the percentage of PD-L1-positive G-cells was 30% higher in infected subjects (p = .011), suggesting that these cells are preferentially rescued from destruction.

CONCLUSIONS

Antral G-cells frequently express PD-L1 during homeostasis. G-cells seem to be protected from H. pylori-induced immune destruction by PD-L1 expression. GIM itself does not express PD-L1 and is unlikely to escape immunosurveillance via expression of PD-L1.

Pharmacoepidemiological Research on N-Nitrosodimethylamine-Contaminated Ranitidine Use and Long-Term Cancer Risk: A Population-Based Longitudinal Cohort Study

N-Nitrosodimethylamine (NDMA), a carcinogenic chemical, has recently been identified in ranitidine. We conducted a population-based study to explore ranitidine use and cancer emergence over time. Using the Taiwan National Health Insurance Research Database, a population-based cohort study was conducted. A total of 55,110 eligible patients who received ranitidine between January 2000 and December 2018 were enrolled in the treated cohort. We conducted a 1:1 propensity-score-matching procedure to match the ranitidine-treated group with the ranitidine-untreated group and famotidine controls for a longitudinal study. The association of ranitidine exposure with cancer outcomes was assessed. A multivariable Cox regression analysis that compared cancer risk with the untreated groups revealed that ranitidine increased the risk of liver (hazard ratio (HR): 1.22, 95% confidence interval (CI): 1.09-1.36, p < 0.001), lung (HR: 1.17, CI: 1.05-1.31, p = 0.005), gastric (HR: 1.26, CI: 1.05-1.52, p = 0.012), and pancreatic cancers (HR 1.35, CI: 1.03-1.77, p = 0.030). Our real-world observational study strongly supports the pathogenic role of NDMA contamination, given that long-term ranitidine use is associated with a higher likelihood of liver cancer development in ranitidine users compared with the control groups of non-ranitidine users treated with famotidine or proton-pump inhibitors.

Effect of Food on the Pharmacokinetics and Pharmacodynamics of a Single Oral Dose of Tegoprazan

PURPOSE

Tegoprazan is a potassium-competitive acid blocker (P-CAB) that is designed to treat acid-related diseases through a fundamentally different mechanism than that of proton pump inhibitors (PPIs). Because PPIs inhibit only activated parietal cell H⁺/K⁺ adenosine triphosphatase, stimulation of parietal cells by a meal is necessary for optimal results. In contrast, P-CABs can inactivate proton pumps without acid activation and bind to both activated and inactivated adenosine triphosphatase. This study evaluates the effect of food consumption on the pharmacokinetic and pharmacodynamic properties of tegoprazan after a single oral dose in healthy men.

METHODS

In this open-label, 2-period crossover study, 24 healthy men were randomized to 1 of 2 treatment sequence groups: administration of tegoprazan under the fasting condition and administration of tegoprazan under the fed condition. The dosing periods of both sequence groups were separated by a washout period of 7 days. At each dosing period, the participants received a single dose of 200 mg of tegoprazan followed by pharmacokinetic and pharmacodynamic analysis.

FINDINGS

After the oral administration of 200 mg tegoprazan, the C_max was decreased and delayed under the fed condition compared with that of the fasting condition. However, no significant differences were observed in the AUC and the time of gastric acid suppression (inhibition of integrated acidity) during 24 hours.

IMPLICATIONS

The pharmacokinetic and pharmacodynamic properties of tegoprazan are independent of food effect; thus, tegoprazan could be administered regardless of the timing of food consumption in patients. ClinicalTrials.gov identifier: NCT01830309.

Pepsinogen Serology and Gastritis OLGA Staging in Mucosal Atrophy Assessment: A Cross-Sectional Study Involving East China Endoscopy Population

The histological gastric stage (OLGA) plays an important role in evaluating gastric atrophy, a symptom which suggests a risk of gastric cancer (GC). However, gastroscopy is an invasive examination, which has limited application in populations undergoing physical examination. Serum pepsinogen (PG) and gastin-17 (G-17) levels are noninvasive indexes which are recommended when screening for GC. We aim to explore the correlation between PG/G-17 and OLGA stage, in order to provide reliable indexes for GC screening. The study included 453 asymptomatic individuals from East China undergoing physical examination, who then underwent endoscopy including collection of biopsy samples. Assays for serum PG, G-17, and Helicobacter pylori (Hp) were performed. Atrophy of gastric mucosa was graded according to OLGA for each individual. 453 participants, average age 52.46 ± 10.30 years, 253 male and 200 female, were included. In the asymptomatic physical examination population, serum PGI, PGII, and PGR levels decreased with increasing OLGA scores. PGI and PGR were inversely correlated with increasing OLGA stage in both Hp-positive and Hp-negative groups. The levels of serum PGI, PGII, and G-17 in the Hp-positive group were higher than those in the Hp-negative group; conversely, the PGR levels were lower. Furthermore, OLGA scores increased with age in the Hp-positive group. In conclusion, there is a significant correlation between OLGA stage and serum PG in populations from East China undergoing physical examination. Serum PG and G-17 combined with Hp test plays an important role in evaluating gastric atrophy.

Association Between Acid-Suppressive Agents’ Use and Risk of Hepatocellular Carcinoma

Background:

Acid-suppressive agents (ASAs), which are mostly used in patients with upper gastrointestinal diseases (UGIDs), may influence the risk of hepatocellular carcinoma (HCC).

Methods:

A population-based retrospective cohort study was conducted. Patients with UGID who used ASAs and those who did not receive ASAs were identified. Patients without UGIDs were randomly selected and matched (comparison group). All groups were followed up for 6 years. A Cox proportional hazard model was used to estimate the risk of HCC among the different groups.

Results:

Patients with UGID who used ASAs had a significantly elevated HCC risk (adjusted hazard ratio [HR] 1.53; 95% confidence interval [CI], 1.32-1.76] compared to those who did not use ASAs. Patients with UGID who used more than 540 defined daily doses of ASAs had a significantly higher risk of HCC (adjusted HR 2.04; 95% CI, 1.62-2.58). Moreover, the dose effect on HCC risk exhibited a significant increasing trend ( P < .01). Furthermore, patients with UGID who did not use ASAs had a significantly elevated HCC risk (adjusted HR 1.94; 95% CI, 1.59-2.36) compared to the comparison group.

Conclusion:

The use of ASAs increased the risk of HCC in patients with UGIDs, and the effect of ASAs was dose dependent. In addition, UGIDs alone increased the risk of HCC.

Randomised clinical trial: safety, tolerability, pharmacokinetics, and pharmacodynamics of single and multiple oral doses of tegoprazan (CJ-12420), a novel potassium-competitive acid blocker, in healthy male subjects

BACKGROUND

Tegoprazan (CJ-12420) is a potassium-competitive acid blocker (P-CAB) with therapeutic potential for gastro-oesophageal reflux disease (GERD) by reversibly suppressing gastric H⁺ /K⁺ -ATPase.

AIMS

To investigate the safety, tolerability, pharmacokinetics and pharmacodynamics of tegoprazan METHODS: A phase I, randomised, double-blind and placebo-controlled clinical trial was conducted in 56 healthy male subjects without Helicobacter pylori infection. In the single ascending dose study, 50, 100, 200 and 400 mg tegoprazan were administered to 32 subjects. In the multiple ascending dose study, 100 and 200 mg tegoprazan were administered every 24 hours to each of the eight subjects for 7 days. In the comparative pharmacodynamics study, 40 mg esomeprazole was administered to eight subjects every 24 hours for 7 days. The assessment included safety, tolerability, pharmacodynamics through monitoring of 24-hour gastric pH and pharmacokinetics of tegoprazan in plasma and urine.

RESULTS

Tegoprazan was generally well tolerated. Most adverse events reported in the study were mild in intensity and resolved without any sequelae. Exposure to tegoprazan increased in a dose-proportional manner. Multiple dosing with tegoprazan showed no accumulation in plasma on day 7. The pharmacodynamic analysis revealed that tegoprazan showed rapid, dose-dependent gastric acid suppression.

CONCLUSIONS

Tegoprazan was well tolerated and showed rapid and potent gastric acid suppression. This supports the further development of tegoprazan as a treatment for acid-related disorders.

Association Between Cholangiocarcinoma and Proton Pump Inhibitors Use: A Nested Case-Control Study

Background: The present study aimed to examine the odds of cholangiocarcinoma (CCA) in patients with proton pump inhibitors (PPIs) use. Methods: A nested case-control study design was employed using data obtained from Taiwan's National Health Insurance Research Database. In total, 2,293 patients with confirmed diagnosis of CCA were identified and served as the CCA group. The CCA patients were propensity score-matched with 2,293 subjects without CCA who served as the control group. The cumulative defined daily dose (DDD) of PPIs was calculated based on the total supply in days and quantity of individual PPIs. Univariable and multivariate logistic regression models were used to determine the odds of CCA, and calculated odds ratios (ORs) and 95% confidence intervals (CI) were used to assess PPIs use and odds of CCA. Results: The overall adjusted OR of PPIs use-associated CCA was 2.58 (95% CI 2.27, 2.93). The adjusted OR of CCA by cumulative DDD dose of PPIs and CCA was analyzed and revealed those odds of CCA are associated with all types of PPIs. Conclusions: There were odds of intrahepatic and extrahepatic CCA among PPIs users. All PPIs use was associated with odds of CCA. Analyses of larger numbers of cases are needed to confirm these findings.

Serum gastrin and cholecystokinin are associated with subsequent development of gastric cancer in a prospective cohort of Finnish smokers

Background

Gastrin, which induces gastric acid secretion, and a structurally similar hormone, cholecystokinin (CCK)-a potent acid inhibitor, may each play a role in gastric cancer. However, few studies have investigated this hypothesis in humans. We therefore investigated whether serum gastrin or CCK concentrations at baseline were associated with the incidence of gastric non-cardia adenocarcinomas (GNCA), oesophagogastric junctional adenocarcinomas (EGJA) or gastric carcinoid tumours over 24 years of follow-up in a study nested within the all-male Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study of Finnish smokers.

Methods

Totals of 283 incident GNCA, 96 EGJA and 10 gastric carcinoid cases, and 778 matched controls, were included in our analysis. Gastrin and CCK were measured using specific radioimmunoassays. Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated by multivariable logistic regression with adjustment for all known or suspected confounding factors, including Helicobacter pylori seropositivity.

Results

Those with high gastrin (Q4 vs Q1), had an increased risk of GNCA (fully adjusted OR: 1.92; 95% CI: 1.21, 3.05) and gastric carcinoids, though the small number of carcinoid cases meant the fully adjusted model was unstable (age-adjusted continuous model OR: 4.67; 95% CI: 2.67, 8.15). CCK was associated with risk of GNCA only for those in Q3 relative to Q1 (OR: 0.56; 95% CI: 0.33, 0.96), and no significant trend was observed.

Conclusions

Our data suggest that high serum concentrations of gastrin may be associated independently with an increased risk of gastric cancer; the role of CCK in cancer risk is less clear.

A novel K+ competitive acid blocker, YH4808, sustains inhibition of gastric acid secretion with a faster onset than esomeprazole: randomised clinical study in healthy volunteers

BACKGROUND

YH4808, a K⁺ -competitive acid blocker, is under clinical development for the treatment of acid-related disorders, such as gastroesophageal reflux disease.

AIMS

To determine the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of YH4808, compared to placebo and esomeprazole.

METHODS

This double-blind, randomised, placebo- and active comparator (esomeprazole)-controlled study was conducted with 123 healthy male volunteers. We evaluated YH4808 (30-800 mg) properties, administered in single (N=55) and multiple (N=24) oral doses, and recorded the effects on 24-hour intragastric acidity. Results were compared to placebo (N=20) and esomeprazole 40 mg (N=24).

RESULTS

Plasma YH4808 exposure increased dose-proportionally and declined in a multi-phasic manner. YH4808 ≥200 mg/d maintained intragastric acidity at pH >4 for longer times than esomeprazole during both day and night (%Time at pH >4: >70% vs 58% of a 24-hour period, respectively; and >50% vs 33% of a 9-hour night respectively). A twice-daily regimen of YH4808 more effectively controlled intragastric pH at night than a once-daily regimen. In evaluating the mean areas under the intragastric pH-time curves in 15-minute intervals for 2 hours after dosing, we found that YH4808 had a faster onset than esomeprazole. Moreover, unlike esomeprazole, YH4808 PK and PD were not significantly affected by the CYP2C19 genotype of the subjects. YH4808 was well-tolerated at all doses administered.

CONCLUSION

This study showed that YH4808 produced a rapid, sustained suppression of gastric secretion with good tolerability. The results at YH4808 ≥200 mg/d provide a rationale for further clinical investigations in populations with acid-related diseases.

Gastrin and Gastric Cancer

Gastric cancer is the third leading cause of cancer-related mortality worldwide. Despite progress in understanding its development, challenges with treatment remain. Gastrin, a peptide hormone, is trophic for normal gastrointestinal epithelium. Gastrin also has been shown to play an important role in the stimulation of growth of several gastrointestinal cancers including gastric cancer. We sought to review the role of gastrin and its pathway in gastric cancer and its potential as a therapeutic target in the management of gastric cancer. In the normal adult stomach, gastrin is synthesized in the G cells of the antrum; however, gastrin expression also is found in many gastric adenocarcinomas of the stomach corpus. Gastrin's actions are mediated through the G-protein-coupled receptor cholecystokinin-B (CCK-B) on parietal and enterochromaffin cells of the gastric body. Gastrin blood levels are increased in subjects with type A atrophic gastritis and in those taking high doses of daily proton pump inhibitors for acid reflux disease. In experimental models, proton pump inhibitor-induced hypergastrinemia and infection with Helicobacter pylori increase the risk of gastric cancer. Understanding the gastrin:CCK-B signaling pathway has led to therapeutic strategies to treat gastric cancer by either targeting the CCK-B receptor with small-molecule antagonists or targeting the peptide with immune-based therapies. In this review, we discuss the role of gastrin in gastric adenocarcinoma, and strategies to block its effects to treat those with unresectable gastric cancer.

Pernicious anemia and colorectal cancer risk - A nested case-control study

BACKGROUND

Hypergastrinemia was shown to stimulate colonic epithelial cell proliferation.

AIMS

To evaluate the association between pernicious anemia (PA), a disease with hypergastrinemia, and colorectal cancer (CRC) risk.

METHODS

We conducted a nested case-control study within a large database from the UK. Cases were defined as all individuals in the cohort with at least one medical code for CRC. Controls were selected based on incidence-density sampling. For each case, up to four eligible controls were matched on age at diagnosis, sex, practice-site, and both duration and calendar time of follow-up. Exposure of interest was diagnosis of PA prior to CRC diagnosis date. The primary analysis was a multivariable conditional logistic regression.

RESULTS

Our study included 22,098 CRC cases and 85,969 matched controls. We identified 154 (0.70%) cases and 563 (0.65%) controls with past history of PA. The adjusted OR for the association between PA and CRC risk was 1.02 (95% CI 0.85-1.22). There was no difference in the results after stratification according to sex. In a sensitivity analysis only among individuals without chronic use of proton pump inhibitors (PPIs) the adjusted OR was 1.14 (95% CI 0.90-1.45). There was no association between duration of PA and CRC risk.

CONCLUSION

PA is not associated with higher CRC risk.

Gastric neuroendocrine neoplasms and proton pump inhibitors: fact or coincidence?

OBJECTIVE

Reporting on three cases of gastric neuroendocrine tumors (g-NETs) in patients taking long-term proton pump inhibitors (PPIs). These tumors are not classifiable considering current criteria. g-NETs are currently grouped as: types 1 and 2, related to hypergastrinemia due to chronic atrophic gastritis and Zollinger-Ellison syndrome respectively, and type 3, normogastrinemic and more aggressive. Although the g-NETs onset in patients taking PPIs is biologically plausible, only a few cases have been reported so far.

MATERIALS AND METHODS

From January 2005 to July 2014, 31 g-NETs were referred to our Unit: 24 (77%), one (3%) and three (10%) resulted types 1, 2 and 3, respectively. Three cases (10%) did not meet the current classification criteria.

RESULTS

The three patients were administered long-term PPIs for gastro-esophageal reflux disease. Patient 1: a 78-year-old man, with a 4-mm well-differentiated g-NET (Ki-67<1%) and marked hypergastrinemia. Patient 2: a 58-year-old man affected by a 6-mm well-differentiated (Ki-67 = 4%) g-NET, with normal gastrin levels. Patients 3: a 67-year-old woman with an 18-mm well-differentiated g-NET (Ki-67 <2%), with mild hypergastrinemia. In the three patients, histology and pertinent blood tests excluded chronic atrophic gastritis, Helicobacter pylori infection or Zollinger-Ellison syndrome. The first two patients underwent endoscopic polypectomy; in the third case total gastrectomy was performed. Further clinical, endoscopic and imaging follow-up did not show any g-NET recurrence.

CONCLUSIONS

The present data point to the existence and epidemiological relevance of g-NETs associated with PPIs intake. These neoplasms are not included in the current classification, thus their treatment and follow-up have not been established.

The Role of Gastrin and CCK Receptors in Pancreatic Cancer and other Malignancies

The gastrointestinal (GI) peptide gastrin is an important regulator of the release of gastric acid from the stomach parietal cells and it also plays an important role in growth of the gastrointestinal tract. It has become apparent that gastrin and its related peptide cholecystokinin (CCK) are also significantly involved with growth of GI cancers as well as other malignancies through activation of the cholecystokinin-B (CCK-B) receptor. Of interest, gastrin is expressed in the embryologic pancreas but not in the adult pancreas; however, gastrin becomes re-expressed in pancreatic cancer where it stimulates growth of this malignancy by an autocrine mechanism. Strategies to down-regulate gastrin or interfere with its interface with the CCK receptor with selective antibodies or receptor antagonists hold promise for the treatment of pancreatic cancer and other gastrin--responsive tumors.

Safety of proton pump inhibitors and risk of gastric cancers: review of literature and pathophysiological mechanisms

INTRODUCTION

Despite being an overall safe drug, several long-term adverse effects are associated with proton pump inhibitors (PPIs). The link between PPI use and gastric neuroendocrine tumors (NETs), gastric adenocarcinomas and Barrett's esophagus progression gastric cancers has been investigated due to PPI-induced hypergastrinemia.

AREAS COVERED

The pathophysiological mechanisms underlying PPI exposure and gastric NETs, gastric adenocarcinomas and Barrett's esophagus progression are discussed. The quality of randomized control studies, cohort studies and case reports investigating the link between gastric cancers and PPIs are examined. Recommendations for clinicians are provided.

EXPERT OPINION

PPIs cause a hypergastrinemic state, increasing enterochromaffin-like cell dysplasia and risk of gastric NET development, increasing gastritis severity in the context of Helicobacter pylori infection, and progression of carcinogenesis in a certain predisposed subset of Barrett's esophagus patients. There are case reports of PPI-induced gastric NETs and adenocarcinomas as consequences of these effects. In pernicious anemia and chronic gastritis, clinicians should be aware of potential increased risk of gastric NET development with chronic PPI use in these patients. Eradication status of H. pylori prior to commencing long-term PPI therapy should be established to reduce the risk of severe atrophic gastritis and development of gastric dysplasia.

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.

Helicobacter pylori, HIV and Gastric Hypochlorhydria in the Malawian Population

BACKGROUND

HIV and Helicobacter pylori are common chronic infections in sub-Saharan Africa. Both conditions can predispose to gastric hypochlorhydria that may be a risk factor for enteric infections and reduced drug absorption. We have investigated to what extent HIV and H. pylori infections are associated with hypochlorhydria in a Malawian cohort of patients undergoing endoscopy.

METHODS

104 sequential symptomatic adults referred for gastroscopy at Queen Elizabeth Central Hospital, Blantyre, Malawi, had blood taken for rapid HIV testing and fasting serum gastrin analysis. Gastric fluid was aspirated for pH testing, and gastric biopsies were taken.

RESULTS

After 9/104 HIV-infected patients who were already established on anti-retroviral therapy were excluded, 17/95 (25.0%) were seropositive for untreated HIV, and 68/95 (71.6%) patients were H. pylori positive by histology. Hypochlorhydria (fasting gastric pH>4.0) was present in 55.8% (53/95) of patients. H. pylori infection was significantly associated with hypochlorhydria (OR 2.91, [1.02-7.75], p=0.046). While single infection with HIV was not significantly independently associated with hypochlorhydria. H. pylori and HIV co-infection was more strongly associated with hypochlorhydria (OR 6.25, [1.33-29.43], p=0.020) than either infection alone, suggesting an additive effect of co-infection. HIV infection was associated with higher serum gastrin levels (91.3 pM vs. 53.1 pM, p=0.040), while H. pylori infection was not (63.1 pM vs. 55.1 pM, p=0.610). Irrespective of H. pylori and HIV status, most patients (>90%) exhibited pangastritis. Only three patients had histological evidence of gastric atrophy, of which only one was HIV-infected.

CONCLUSION

H. pylori infection was associated with fasting hypochlorhydria, while HIV was not independently associated. HIV and H. pylori co-infection, however, was more strongly associated with hypochlorhydria than H. pylori infection alone. The mechanism of this apparent additive effect between HIV and H. pylori remains unclear, but appears to be related to chronic pangastritis rather than gastric atrophy, and associated with hypergastrinaemia in HIV-infected individuals.

Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of Single Rising TAK-438 (Vonoprazan) Doses in Healthy Male Japanese/non-Japanese Subjects

OBJECTIVES:

To evaluate safety, tolerability, pharmacokinetics, and pharmacodynamics of TAK-438 (vonoprazan, a potassium-competitive acid blocker) in healthy male subjects.

METHODS:

In two phase I, randomized, double-blind, placebo-controlled, single rising-dose studies, healthy male subjects (Japan N=84; UK N=63) received a single TAK-438 dose (1–120 mg in Japan and 1–40 mg in the UK). Assessments included safety, tolerability, pharmacokinetics, and pharmacodynamics (intragastric pH).

RESULTS:

Plasma concentration–time profiles of TAK-438 at all dose levels showed rapid absorption (median T_max up to 2 h). Estimated mean elimination half-life was up to 9 h. Exposure was slightly greater than dose proportional. No clear difference in TAK-438 pharmacokinetics was observed between Japanese and non-Japanese subjects. Acid suppression was dose dependent and similar in both studies. The 24-h intragastric pH ≥4 holding time ratio with 40 mg TAK-438 was 92% in Japan and 87% in the UK. TAK-438 was well tolerated, with no adverse events reported in Japanese subjects; 10 of 63 UK subjects experienced 12 treatment-emergent adverse events (non-serious). Increases in serum gastrin and pepsinogen I and II concentrations were observed at doses ≥10 mg, but there were no changes in alanine aminotransferase concentrations.

CONCLUSIONS:

Single oral doses of TAK-438 20–120 mg caused rapid, profound, and 24-h suppression of gastric acid secretion in healthy male subjects, regardless of geographical region, and TAK-438 was well tolerated at all doses studied, making it a potential alternative to proton pump inhibitors for the treatment of acid-related disorders.

Randomised clinical trial: safety, tolerability, pharmacokinetics and pharmacodynamics of repeated doses of TAK-438 (vonoprazan), a novel potassium-competitive acid blocker, in healthy male subjects

BACKGROUND

TAK-438 (vonoprazan) is a potassium-competitive acid blocker that reversibly inhibits gastric H(+) , K(+) -ATPase.

AIM

To evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics of TAK-438 in healthy Japanese and non-Japanese men.

METHODS

In two Phase I, randomised, double-blind, placebo-controlled studies, healthy men (Japan N = 60; UK N = 48) received TAK-438 10-40 mg once daily at a fixed dose level for 7 consecutive days. Assessments included safety, tolerability, pharmacokinetics and pharmacodynamics (intragastric pH).

RESULTS

Plasma concentration-time profiles of TAK-438 at all dose levels showed rapid absorption (median Tmax ≤2 h). Mean elimination half-life was up to 9 h. Exposure was slightly greater than dose proportional, with no apparent time-dependent inhibition of metabolism. There was no important difference between the two studies in AUC0-tau on Day 7. TAK-438 caused dose-dependent acid suppression. On Day 7, mean 24-h intragastric pH>4 holding time ratio (HTR) with 40 mg TAK-438 was 100% (Japan) and 93.2% (UK), and mean night-time pH>4 HTR was 100% (Japan) and 90.4% (UK). TAK-438 was well tolerated. The frequency of adverse events was similar at all dose levels and there were no serious adverse events. There were no important increases in serum alanine transaminase activity. Serum gastrin and pepsinogen I and II concentrations increased with TAK-438 dose.

CONCLUSIONS

TAK-438 in multiple rising oral dose levels of 10-40 mg once daily for 7 days was safe and well tolerated in healthy men and caused rapid, profound and sustained suppression of gastric acid secretion throughout each 24-h dosing interval. Clinicaltrials.gov identifiers: NCT02123953 and NCT02141711.

Hypergastrinemia

Gastrin is an important hormone of the digestive system, which assists gastric acid secretion. It may be pathologically elevated in conditions such as Zollinger-Ellison syndrome, or due to common medications such as proton pump inhibitors. In this review we provide an overview of the pathophysiology and medical causes of hypergastrinemia, diagnostic testing and clinical consequences of chronic hypergastrinemia.

Diagnosis of pernicious anemia and the risk of pancreatic cancer

OBJECTIVES

A number of studies have demonstrated a trophic effect of gastrin on pancreatic cancer cells in vitro. Pernicious anemia (PA) is a clinical condition characterized by chronic hypergastrinemia. The aim of this study was to determine if PA is a risk factor for pancreatic cancer.

METHODS

This study is a retrospective cohort study using The Health Improvement Network database, which contains comprehensive health information on 7.5 million patients in the United Kingdom from 1993 to 2009. All patients with PA in the study cohort were identified and composed of the exposed group. Each exposed patient was matched on practice site, sex, and age with up to 4 unexposed patients without PA. The outcome was incident pancreatic cancer. The hazard ratio and 95% confidence intervals were estimated using multivariable Cox regression analysis.

RESULTS

We identified 15,324 patients with PA and 55,094 unexposed patients. Mean follow-up time was similar between groups (exposed 4.31 [SD, 3.38] years, unexposed 4.63 [SD, 3.44] years). The multivariable adjusted hazard ratio for pancreatic cancer associated with PA was 1.16 (95% confidence interval, 0.77-1.76; P = 0.47).

CONCLUSIONS

There is no significant association between PA and the risk of pancreatic cancer.

Acid peptic diseases: pharmacological approach to treatment

Acid peptic disorders are the result of distinctive, but overlapping pathogenic mechanisms leading to either excessive acid secretion or diminished mucosal defense. They are common entities present in daily clinical practice that, owing to their chronicity, represent a significant cost to healthcare. Key elements in the success of controlling these entities have been the development of potent and safe drugs based on physiological targets. The histamine-2 receptor antagonists revolutionized the treatment of acid peptic disorders owing to their safety and efficacy profile. The proton-pump inhibitors (PPIs) represent a further therapeutic advance due to more potent inhibition of acid secretion. Ample data from clinical trials and observational experience have confirmed the utility of these agents in the treatment of acid peptic diseases, with differential efficacy and safety characteristics between and within drug classes. Paradigms in their speed and duration of action have underscored the need for new chemical entities that, from a single dose, would provide reliable duration of acid control, particularly at night. Moreover, PPIs reduce, but do not eliminate, the risk of ulcers in patients taking NSAIDs, reflecting untargeted physiopathologic pathways and a breach in the ability to sustain an intragastric pH of more than 4. This review provides an assessment of the current understanding of the physiology of acid production, a discussion of medications targeting gastric acid production and a review of efficacy in specific acid peptic diseases, as well as current challenges and future directions in the treatment of acid-mediated diseases.

Characterization of gastrins and their receptor in solid human gastric adenocarcinomas

OBJECTIVE

The gastrin and the gastrin/CCK-B receptor genes are co-expressed in several carcinomas. The primary translational product, progastrin, however, is processed to several peptides of which only those that are α-amidated at their C-terminus are receptor ligands. So far, characterization of the progastrin-derived peptides in gastric cancer has not been reported. The authors therefore examined the molecular nature of gastrin and its receptor in human gastric carcinomas.

MATERIALS AND METHODS

Twenty patients with adenocarcinoma underwent partial or total gastrectomy. In samples from each carcinoma, gastrin peptides were characterized, using a library of sequence-specific immunoassays. Expression was also demonstrated by immunohistochemistry. In addition, the gastrin and gastrin/CCK-B receptor gene expression was quantitated using real-time PCR, and the receptor protein demonstrated by western blotting.

RESULTS

α-Amidated gastrins were detectable in 16 of 20 carcinomas (median concentration 2.1 pmol/g tissue; range 0-386 pmol/g tissue). The tissue concentrations correlated closely to the gastrin mRNA contents (r = 0.75, p < 0.0001). Moreover, progastrin and non-amidated processing intermediates, including glycine-extended gastrins, were detected in 19 carcinomas. Immunohistochemistry corroborated gastrin expression in carcinoma cells. Chromatography revealed extensive progastrin processing with α-amidated gastrin-34 and -17 (tyrosyl-sulfated as well as non-sulfated) as major products. Finally, gastrin/CCK-B receptor mRNA and protein were detected in all tumors.

CONCLUSIONS

The results show that the elements for a local loop of α-amidated gastrins and their receptor are detectable in 80% of human gastric adenocarcinomas. Therefore, the results support the contention that locally expressed gastrin may be involved in the tumorigenesis of gastric adenocarcinomas.

Neuroendocrine proliferations of the stomach: a pragmatic approach for the perplexed pathologist

The classifications of neuroendocrine proliferations that lead from enterochromaffin-like cell hyperplasia to neuroendocrine tumors in the stomach are complicated and relatively inaccessible to nonspecialists. Consequently, these lesions tend to remain widely underdiagnosed until they progress to easily recognizable neuroendocrine tumors. This review provides simple, yet rigorous guidelines on how to recognize, classify, and diagnose the neuroendocrine proliferations found in the stomach, emphasizing the most common background in which they arise, atrophic gastritis. After a succinct outline of the types and distribution of the neuroendocrine cells in the normal gastric mucosa we discuss the most common situations in which the pathologist needs to think about gastric neuroendocrine cells. In general practice gastric biopsy specimens are often numerically and topographically inadequate for the evaluation of atrophic gastritis; therefore, we have included an algorithm to address specifically the steps that should be taken when confronted with suboptimal sampling. Finally, we illustrate the suggested diagnostic process with 4 cases that are fairly representative of the type of situations encountered in everyday practice. The pathologist who follows our simple steps will be better aware of this neglected area of gastric pathology and will learn to suspect, recognize, and accurately diagnose the most common abnormalities of the neuroendocrine system in the stomach.

No higher risk for colorectal cancer in atrophic gastritis-related hypergastrinemia

BACKGROUND

Atrophic gastritis of the corporal mucosa is a frequent cause of hypergastrinemia. Hypergastrinemia is implicated in colorectal cancer development.

AIM

To assess whether hypergastrinemic atrophic gastritis is associated with a higher risk of neoplastic colorectal lesions.

METHODS

Among 441 hypergastrinemic atrophic gastritis patients, 160 who were aged >40 and underwent colonoscopy for anaemia, diarrhoea or colorectal cancer-screening were retrospectively selected. Each patient was age- and gender-matched with a normogastrinemic control with healthy stomach. Controls had colonoscopy, gastroscopy with biopsies and gastrin assessment.

RESULTS

160 hypergastrinemic atrophic gastritis patients and 160 controls were included. 28 atrophic gastritis patients and 36 controls had neoplastic colorectal lesions (p=0.33). Patients and controls did not differ for frequency of colorectal adenomas (10.6% vs. 13.1%, p=0.60) or cancer (6.9% vs. 9.4%, p=0.54). Hypergastrinemic atrophic gastritis was not associated with a higher probability of developing colorectal cancer (OR 1.03, 95% CI 0.34-3.16). Age >50 years (OR 3.86) but not hypergastrinemia (OR 0.61) was associated with colorectal cancer.

CONCLUSIONS

Hypergastrinemic atrophic gastritis is not associated with higher risk for colorectal cancer. Atrophic gastritis-related hypergastrinemia is not associated with an increased risk of neoplastic colorectal lesions. Closer surveillance of colonic neoplasia in atrophic gastritis patients seems not appropriate.

Gastroprotective and ulcer healing effects of essential oil from Hyptis spicigera Lam. (Lamiaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Hyptis Jacq. (Lamiaceae) is being used in traditional medicine to treat fever, inflammation and gastric disturbances. Hyptis spicigera Lam. is a native plant distributed across the central region of Brazil. The essential oil extracted from this plant is used in folk medicine as antipyretic.

AIM OF THE STUDY

The effects of the essential oil obtained from the aerial parts of Hyptis spicigera (OEH) were evaluated for their gastroprotective and healing activities.

MATERIALS AND METHODS

OEH chemical composition was analyzed by gas chromatography-mass spectrometry (GC-MS). The gastroprotective action of the OEH was evaluated in rodent experimental models (ethanol and NSAID). To elucidate mechanisms of action, the antisecretory action and involvements of NO, SH, mucus and PGE2 were evaluated. The acetic acid-induced gastric ulcer model and Western Blot assay (COX-2 and EGF) were also used to evaluate the OEH healing capacity.

RESULTS

GC-MS analysis of OEH indicated three monoterpenes as major compounds: alpha-pinene (50.8%), cineole (20.3%) and beta-pinene (18.3%) and, at the dose of 100 mg/Kg, p.o., OEH provided effective gastroprotection against lesions induced by absolute ethanol (97%) and NSAID (84%) in rats. OEH do not interfere with H+ secretion in gastric mucosa and its gastric protection does not depend on nitric oxide (NO) and sulfhydryl compounds (SH). The gastroprotective action of OEH occurs due to an increase in the gastric mucus production (28%) induced by PGE2 levels. Furthermore, OEH demonstrated a great healing capacity with 87% of reduction in ulcerative lesion area. It accelerated the healing of acetic acid-induced gastric lesions due to an increase in COX-2 (75%) and EGF (115%) expression in gastric mucosa. No sign of toxicity was observed in this study, considering the analyzed parameters.

CONCLUSIONS

All these results suggest the efficacy and safety of Hyptis spicigera in combating and healing gastric ulcer. Considering the results, it is suggested that the OEH could probably be a good therapeutic agent for the development of new phytotherapeutic medicine for the treatment of gastric ulcer.

Gastrin, inflammation, and carcinogenesis

PURPOSE OF REVIEW

Chronic infection of the gastric mucosa with Helicobacter pylori has long been recognized as a significant risk factor for gastric cancer, and indeed, this model represents the prototypical inflammation-associated cancer. In this review, we present the latest clinical and experimental evidence showing that gastrin peptides and their receptors [the cholecystokinin (CCK2) receptors] potentiate the progression of gastric cancer and other gastrointestinal malignancies in the presence of inflammation.

RECENT FINDINGS

We highlight the feed-forward mechanisms by which gastrin and CCK2 receptor expression are upregulated during inflammation and in gastrointestinal cancers, summarize gastrin's proinflammatory role by inducing the production of cyclooxgenase-2 (COX-2) and interleukin-8 (IL-8), and relate evidence suggesting that gastrin and their receptors modulate the function of immune cells and fibroblasts following cellular stress, injury, repair, as well as during cancer progression.

SUMMARY

We discuss trends for future studies directed toward the elucidation of gastrin peptides' role in regulating intercellular molecular signaling mechanisms between local and circulating immune cells, fibroblasts, epithelial cells, and other cell types in the microenvironments of inflammation-related cancers. Elucidation of the molecular and cellular pathways that relate inflammation with cancer may provide additional opportunities to develop complementary therapies that target the inflammatory microenvironment of the cancer.

Classification of anemia for gastroenterologists

Most anemia is related to the digestive system by dietary deficiency, malabsorption, or chronic bleeding. We review the World Health Organization definition of anemia, its morphological classification (microcytic, macrocytic and normocytic) and pathogenic classification (regenerative and hypo regenerative), and integration of these classifications. Interpretation of laboratory tests is included, from the simplest (blood count, routine biochemistry) to the more specific (iron metabolism, vitamin B12, folic acid, reticulocytes, erythropoietin, bone marrow examination and Schilling test). In the text and various algorithms, we propose a hierarchical and logical way to reach a diagnosis as quickly as possible, by properly managing the medical interview, physical examination, appropriate laboratory tests, bone marrow examination, and other complementary tests. The prevalence is emphasized in all sections so that the gastroenterologist can direct the diagnosis to the most common diseases, although the tables also include rare diseases. Digestive diseases potentially causing anemia have been studied in preference, but other causes of anemia have been included in the text and tables. Primitive hematological diseases that cause anemia are only listed, but are not discussed in depth. The last section is dedicated to simplifying all items discussed above, using practical rules to guide diagnosis and medical care with the greatest economy of resources and time.

Primary liver carcinoid tumour with a Zollinger Ellison syndrome - an unusual diagnosis: a case report

Carcinoids are neuroendocrine tumours which may secrete hormones like gastrin, insulin, ACTH, etc. Liver is a common site for metastasis of carcinoid origin and an unusual site for a primary carcinoid tumour to arise.

We present the case of a 51-year-old Caucasian man with diarrhoea, weight loss, duodenum ulcers and a liver mass in ultrasonography. A primary hepatic carcinoid tumour with a Zollinger Ellison syndrome was diagnosed. Surgery resection was performed and the patient remained free of symptoms two years after, with normalisation of gastrin levels.

Primary hepatic carcinoid tumour represents an uncommon diagnosis, based on radiological and pathological features. The exclusion of different primary locations is necessary. Once associated with a Zollinger Ellison syndrome, diagnose may be more complicated and challenging since only 7 cases of hepatic carcinoids with gastrin secretion were reported in medical literature.

A review of medical literature is performed and diagnoses tools that should be used for an accurate diagnosis and available treatment approaches are commented here.

Review article: Strategies to determine whether hypergastrinaemia is due to Zollinger-Ellison syndrome rather than a more common benign cause

BACKGROUND

As there is considerable overlap between the fasting serum gastrin concentrations found in Zollinger-Ellison syndrome and various common conditions such as Helicobacter pylori infection and acid suppressing medication use, establishing the cause of hypergastrinaemia in individual cases can sometimes be difficult.

AIM

To review the causes of hypergastrinaemia and the role of additional non-invasive investigations in hypergastrinaemic patients.

METHODS

Review of articles following a Pubmed search.

RESULTS

As gastrinomas may cause serious complications and be potentially life threatening, investigation of hypergastrinaemic patients should particularly focus on confirming or refuting the diagnosis of Zollinger-Ellison syndrome. Establishing the cause of hypergastrinaemia may be difficult when there is only a mild-to-moderate elevation of fasting serum gastrin concentration and concurrent treatment with proton pump inhibitor drugs and the presence of H. pylori infection can both confuse the clinical picture. A variety of provocative tests are therefore useful for establishing whether a hypergastrinaemic patient has a gastrinoma and current evidence suggests that the secretin test should be used first line.

CONCLUSIONS

We suggest an algorithm for the investigation of patients found to have an elevated fasting serum gastrin concentration and address the roles of gastrin stimulation tests in current clinical practice.

Long-term proton pump inhibitor use and gastrointestinal cancer

Proton pump inhibitors profoundly affect the stomach and have been associated with carcinoid tumors in female rats. There is now sufficient experience with this class of drugs to allow reasonable estimation of their safety in terms of cancer development in humans. Long-term use of proton pump inhibitors is associated with an increase in gastric inflammation and development of atrophy among those with active Helicobacter pylori infections. The actual risk is unknown but is clearly low. However, it can be markedly reduced or eliminated by H. pylori eradication. It is thus recommended that patients being considered for long-term proton pump inhibitor therapy should be tested for H. pylori infection and, if present, this pathogen should be eradicated. Oxyntic cell hyperplasia, glandular dilatations, and fundic gland polyps may develop in patients not infected with H. pylori, but these changes are believed to be reversible and without significant cancer risk.

Gastric secretion

PURPOSE OF REVIEW

This review summarizes the past year's literature regarding the regulation and assessment of gastric acid secretion.

RECENT FINDINGS

Gastric acid secretion is regulated by biologic agents produced and released by enteroendocrine cells and neurons as well as by exogenously administered substances and infection. Too much acid can lead to gastroesophageal reflux disease, peptic ulcer disease, and stress-related erosion/ulcer disease. Too little acid can interfere with the absorption of certain nutrients, predispose to enteric infection, and interfere with the absorption of some medications. Gastrin, histamine, gastrin-releasing peptide, ghrelin, orexin, and glucocorticoids stimulate whereas leptin, glucagon-like peptide 1, and Helicobacter pylori inhibit acid secretion. Helicobacter pylori inhibits the transcriptional activity of HK-ATPase, the proton pump of the parietal cell.

SUMMARY

A better understanding of the pathways and mechanisms regulating gastric acid secretion should lead to improved management of patients with acid-induced disorders as well as those who secrete too little acid.

Dynamic physiological and molecular changes in gastric ulcer healing achieved by melatonin and its precursor L-tryptophan in rats

Following induction of gastric ulcer in rats by serosal application of acetic acid, local mucosal necrosis ensues accompanied by a reduction in mucosal microcirculation and by almost immediate expression of inducible nitric oxide (NO) synthase (iNOS) and proinflammatory cytokines. Daily application of melatonin (20 mg/kg) or l-tryptophan (100 mg/kg) accelerates ulcer healing by affecting the cyclooxygenase-2 (COX-2)-prostaglandin (PG) system with excessive production of protective PG, especially in later period of ulcer healing. Furthermore, expression of hypoxia inducible factor, vascular-endothelial growth factor, an activation of cNOS-NO system and the stimulation of sensory nerves with the expression and release of calcitonin gene related peptide (CGRP) appear to aid the restoration of mucosal repair and microcirculation in the ulcer bed. The enhanced expression of the melatonin MT(2) receptors (MT(2)-R) combined with overexpression of key enzymes involved in biosynthesis of melatonin such as N-acetyltransferase and hydroxyindole-O-methyltransferase contribute to the acceleration of ulcer healing by this indole. Melatonin-induced acceleration of ulcer healing is also mediated by release of gastrin and ghrelin, the most potent stimulants of gastric mucosal cell proliferation and mucosal repair. These sequential steps in ulcer healing accelerated by melatonin can be interfered with by the blockade of MT(2)R, COX-2/PG and cNOS/NO systems, and by reduction in the inflammatory iNOS/NO system. Thus, melatonin and its precursor l-tryptophan, trigger the cascade of molecular events leading to the functional improvement in ulcer healing.

Regulated expression of the human gastrin gene in mice

Gastrin is secreted from neuroendocrine cells residing in the adult antrum called G cells, but constitutively low levels are also expressed in the duodenum and fetal pancreas. Gastrin normally regulates gastric acid secretion by stimulating the proliferation of enterochromaffin-like cells and the release of histamine. Gastrin and progastrin forms are expressed in a number of pathological conditions and malignancies. However, the DNA regulatory elements in the human versus the mouse gastrin promoters differ suggesting differences in their transcriptional control. Thus, we describe here the expression of the human gastrin gene using a bacterial artificial chromosome (BAC) in the antral and duodenal cells of gastrin null mice. All 5 founder lines expressed the 253 kb human gastrin BAC. hGasBAC transgenic mice were bred onto a gastrin null background so that the levels of human gastrin peptide could be analyzed by immunohistochemistry and radioimmunoassay without detecting endogenous mouse gastrin. We have shown previously that chronically elevated gastrin levels suppress somatostatin. Indeed, infusion of amidated rat gastrin depressed somatostatin levels, stimulated gastric acid secretion and an increase in the numbers of G cells in the antrum and duodenum. In conclusion, human gastrin was expressed in mouse enteroendocrine cells and was regulated by somatostatin. This mouse model provides a unique opportunity to study regulation of the human gastrin promoter in vivo by somatostatin and possibly other extracellular regulators contributing to our understanding of the mechanisms involved in transcriptional control of the human gene.