Proton Pump Inhibitors Inhibit Pancreatic Secretion: Role of Gastric and Non-Gastric H+/K+-ATPases

Chronic Use of Proton Pump Inhibitors Is Associated With Reduced 30-Day Mortality From Acute Pancreatitis

Proton pump inhibitors (PPIs) decrease pancreatic exocrine secretions. There has been interest in the impact of their short-term in-hospital administration on acute pancreatitis (AP) outcomes. It is unknown whether long-term use affects AP outcomes. We investigated the association between chronic PPI use and short-term AP outcomes. We included all (2308) patients admitted with a primary diagnosis of AP (625 on chronic PPI use) between January 2008 and June 2021 and evaluated any association between chronic PPI use and 30-day all-cause mortality by univariate logistic regression. Compared to non-users, patients on chronic PPIs were older (p < 0.001) and had a higher Charlson Comorbidity Index score (p < 0.001). Mortality rates at 30 days were 1.6% in chronic PPI users and 4.4% in non-users (OR 0.35; 95% CI, 0.17-0.66; p < 0.002). [Correction added on 18 February 2025, after first online publication: Mortality rates at 30 days in chronic PPI users and non-users were updated in this version.].

Pantoprazole and riluzole target H+/K+-ATPases and pH-sensitive K+ channels in pancreatic cancer cells

Pancreatic ductal adenocarcinoma (PDAC) remains the most lethal cancer type. PDAC is characterized by fibrotic, hypoxic, and presumably acidic tumor microenvironment (TME). Acidic TME is an important player in tumor development, progression, aggressiveness, and chemoresistance. The dysregulation of ductal ion transporters/channels might contribute to extracellular pH (pHe) acidification and PDAC progression. Our aim was to test whether H+/K+-ATPases and pH-sensitive K+ channels contribute to these processes and could be targeted by clinically approved drugs. We used human pancreatic cancer cells adapted to various pHe conditions and grown in monolayers and spheroids. First, we created cells expressing pHoran4 at the outer plasma membrane and showed that pantoprazole, the H+/K+-ATPase inhibitor, alkalinized pHe. Second, we used FluoVolt to monitor the membrane voltage (Vm) and showed that riluzole hyperpolarized Vm, most likely by opening of pH-sensitive K+ channels such as TREK-1. Third, we show that pantoprazole and riluzole inhibited cell proliferation and viability of monolayers and spheroids of cancer cells adapted to various pHe conditions. Most importantly, combination of the two drugs had significantly larger inhibitory effects on PDAC cell survival. We propose that co-targeting H+/K+-ATPases and pH-sensitive K+ channels by re-purposing of pantoprazole and riluzole could provide novel acidosis-targeted therapies of PDAC.

Clinical Implications of Proton Pump Inhibitors and Vonoprazan Micro/Nano Drug Delivery Systems for Gastric Acid-Related Disorders and Imaging

Excessive stomach acid or bacterial infection are the root causes of gastric acid-related disorders, such as peptic ulcer disease and gastroesophageal reflux disease. Proton pump inhibitors including lansoprazole, omeprazole, esomeprazole, rabeprazole, etc. are medications used to treat gastric acid-related diseases. One of the most effective drugs for treating gastroesophageal reflux disease is vonoprazan, owing to its ability to strongly inhibit gastric acid. Proton pump inhibitors and vonoprazan work in distinct ways to prevent the production of stomach acid. Vonoprazan inhibits acid secretion by blocking the potassium-competitive acid blocker receptor, whereas proton pump inhibitors function by irreversibly blocking the proton pump in the parietal cells of the stomach. Delayed release tablets, delayed release capsules, minitablets, pellets, bilayer, floating, mucoadhesive tablets and nanoparticles, are some of the methods used in the development of micro/nano formulations with proton pump inhibitors and vonoprazan. Diagnosis and therapy of gastric acid-related illnesses, particularly those treated with drugs such as vonoprazan and proton pump inhibitors, rely heavily on imaging modalities such as CT scans, X-rays, endoscopy, fluorescence and HRM imaging. This review provides a comprehensive update on various micro/nanoformulations of proton pump inhibitors and vonoprazan. Moreover, we provide an outlook on clinical imaging of proton pump inhibitors and vonoprazan formulation for gastric acid related diseases. We have limited our discussion to case studies and clinical trials on proton pump inhibitors and vonoprazan for gastric acid related disease.

ATP12A Proton Pump as an Emerging Therapeutic Target in Cystic Fibrosis and Other Respiratory Diseases

ATP12A encodes the catalytic subunit of the non-gastric proton pump, which is expressed in many epithelial tissues and mediates the secretion of protons in exchange for potassium ions. In the airways, ATP12A-dependent proton secretion contributes to complex mechanisms regulating the composition and properties of the fluid and mucus lining the respiratory epithelia, which are essential to maintain the airway host defense and the respiratory health. Increased expression and activity of ATP12A in combination with the loss of other balancing activities, such as the bicarbonate secretion mediated by CFTR, leads to excessive acidification of the airway surface liquid and mucus dysfunction, processes that play relevant roles in the pathogenesis of cystic fibrosis and other chronic inflammatory respiratory disorders. In this review, we summarize the findings dealing with ATP12A expression, function, and modulation in the airways, which led to the consideration of ATP12A as a potential therapeutic target for the treatment of cystic fibrosis and other airway diseases; we also highlight the current advances and gaps regarding the development of therapeutic strategies aimed at ATP12A inhibition.

Identifying target ion channel-related genes to construct a diagnosis model for insulinoma

Background: Insulinoma is the most common functional pancreatic neuroendocrine tumor (PNET) with abnormal insulin hypersecretion. The etiopathogenesis of insulinoma remains indefinable. Based on multiple bioinformatics methods and machine learning algorithms, this study proposed exploring the molecular mechanism from ion channel-related genes to establish a genetic diagnosis model for insulinoma. Methods: The mRNA expression profile dataset of GSE73338 was applied to the analysis, which contains 17 insulinoma samples, 63 nonfunctional PNET (NFPNET) samples, and four normal islet samples. Differently expressed ion channel-related genes (DEICRGs) enrichment analyses were performed. We utilized the protein-protein interaction (PPI) analysis and machine learning of LASSO and support vector machine-recursive feature elimination (SVM-RFE) to identify the target genes. Based on these target genes, a nomogram diagnostic model was constructed and verified by a receiver operating characteristic (ROC) curve. Moreover, immune infiltration analysis, single-gene gene set enrichment analysis (GSEA), and gene set variation analysis (GSVA) were executed. Finally, a drug-gene interaction network was constructed. Results: We identified 29 DEICRGs, and enrichment analyses indicated they were primarily enriched in ion transport, cellular ion homeostasis, pancreatic secretion, and lysosome. Moreover, the PPI network and machine learning recognized three target genes (MCOLN1, ATP6V0E1, and ATP4A). Based on these target genes, we constructed an efficiently predictable diagnosis model for identifying insulinomas with a nomogram and validated it with the ROC curve (AUC = 0.801, 95% CI 0.674-0.898). Then, single-gene GSEA analysis revealed that these target genes had a significantly positive correlation with insulin secretion and lysosome. In contrast, the TGF-beta signaling pathway was negatively associated with them. Furthermore, statistically significant discrepancies in immune infiltration were revealed. Conclusion: We identified three ion channel-related genes and constructed an efficiently predictable diagnosis model to offer a novel approach for diagnosing insulinoma.

Endoscopic changes in patients diagnosed with acute pancreatitis

BACKGROUND

There have been long debates on the introduction of proton pump inhibitors into acute pancreatitis therapy as standard treatment. The aim of the study was to assess endoscopic lesions of the upper gastrointestinal tract in patients hospitalized for acute pancreatitis.

METHODS

We carried out a prospective analysis of patients hospitalized in one surgical center who had an upper gastrointestinal tract endoscopic examination performed during the first 48 hours of hospitalization. We performed analysis of basic descriptive statistics along with the Shapiro-Wilk Test, logistic order regression analysis, One-Way Analysis of Variance, and Student's t-test for independent trials.

RESULTS

From January 2016 to December 2019, 476 patients were hospitalized because of acute pancreatitis. The upper gastrointestinal tract endoscopic examination was performed in 85 patients (N.) in the first 48 hours. From the examined group 45 patients (52.94%) developed mild acute pancreatitis, 28 (32.94%) moderate pancreatitis, and 12 (14.12%) severe pancreatitis. Lesions in the endoscopic imaging were observed in 80 patients (94.12%).

CONCLUSIONS

A very high percentage of patients hospitalized for acute pancreatitis present lesions in the endoscopic imaging of the upper gastrointestinal tract. The standard treatment of AP is the administration of non-steroidal anti-inflammatory drugs, which themselves can cause gastric and duodenal mucosal defects. All these factors indicate the need for standard use of proton pump inhibitors in patients hospitalized for acute pancreatitis.

Network pharmacology analysis reveals potential targets and mechanisms of proton pump inhibitors in breast cancer with diabetes

Breast cancer and diabetes are significant health challenges, and effective treatments for both diseases are lacking. Proton pump inhibitors (PPIs) have demonstrated anticancer and hypoglycemic effects, but their mechanisms of action are not yet fully understood. We used the GeneCards and PharmMapper databases to identify therapeutic targets for diabetes,  breast cancer and PPIs. We identified common targets and constructed a regulatory network of diseases and drugs using the STRING database and Cytoscape software. We also explored the binding between small molecule ligands and protein receptors using Discovery Studio software. We identified 33 shared targets for breast cancer, diabetes, and PPIs including lansoprazole, omeprazole, and pantoprazole, which play a critical role in fatty acid transport, insulin resistance, apoptosis, and cancer-related signaling pathways. Our findings demonstrated that PPIs had a strong affinity for AKT1 and MMP9. This study provides insights into the mechanisms of action of PPIs in breast cancer and diabetes and identifies AKT1 and MMP9 as critical targets for future drug development. Our findings highlight the potential of PPIs as a novel therapeutic approach for these challenging diseases.

Long-Term Use of Proton Pump Inhibitors Disrupts Intestinal Tight Junction Barrier and Exaggerates Experimental Colitis

BACKGROUND

Proton pump inhibitors [PPIs] are widely used to treat a number of gastro-oesophageal disorders. PPI-induced elevation in intragastric pH may alter gastrointestinal physiology. The tight junctions [TJs] residing at the apical intercellular contacts act as a paracellular barrier. TJ barrier dysfunction is an important pathogenic factor in inflammatory bowel disease [IBD]. Recent studies suggest that PPIs may promote disease flares in IBD patients. The role of PPIs in intestinal permeability is not clear.

AIM

The aim of the present study was to study the effect of PPIs on the intestinal TJ barrier function.

METHODS

Human intestinal epithelial cell culture and organoid models and mouse IBD models of dextran sodium sulphate [DSS] and spontaneous enterocolitis in IL-10-/- mice were used to study the role of PPIs in intestinal permeability.

RESULTS

PPIs increased TJ barrier permeability via an increase in a principal TJ regulator, myosin light chain kinase [MLCK] activity and expression, in a p38 MAPK-dependent manner. The PPI-induced increase in extracellular pH caused MLCK activation via p38 MAPK. Long-term PPI administration in mice exaggerated the increase in intestinal TJ permeability and disease severity in two independent models of DSS colitis and IL-10-/- enterocolitis. The TJ barrier disruption by PPIs was prevented in MLCK-/- mice. Human database studies revealed increased hospitalizations associated with PPI use in IBD patients.

CONCLUSIONS

Our results suggest that long-term use of PPIs increases intestinal TJ permeability and exaggerates experimental colitis via an increase in MLCK expression and activity.

Acid Suppression and Antibiotics Administered during Infancy Are Associated with Celiac Disease

OBJECTIVE

To investigate why certain at-risk individuals develop celiac disease (CD), we examined the association of proton pump inhibitors (PPI), histamine-2 receptor antagonists (H2RAs), and antibiotic prescriptions in the first 6 months of life with an early childhood diagnosis of CD.

STUDY DESIGN

A retrospective cohort study was performed using the Military Healthcare System database. Children with a birth record from October 1, 2001, to September 30, 2013, were identified. Outpatient prescription records were queried for antibiotic, PPI, and H2RA prescriptions in the first 6 months of life. Cox proportional hazards regression was used to calculate the hazard ratio (HR) of developing CD based on medication exposure. International Classification of Diseases, Ninth Revision, Clinical Modification codes identified children with an outpatient visit for CD.

RESULTS

There were 968 524 children who met the inclusion criteria with 1704 cases of CD in this group. The median follow-up for the cohort was approximately 4.5 years. PPIs (HR, 2.23; 95% CI, 1.76-2.83), H2RAs (HR, 1.94; 95% CI, 1.67-2.26), and antibiotics (HR, 1.14; 95% CI, 1.02-1.28) were all associated with an increased hazard of CD.

CONCLUSIONS

There is an increased risk of developing CD if antibiotics, PPIs and H2RAs are prescribed in the first 6 months of life. Our study highlights modifiable factors, such as medication stewardship, that may change the childhood risk of CD.

No evidence for the benefit of PPIs in the treatment of acute pancreatitis: a systematic review and meta-analysis

Although current guidelines do not recommend the use of proton pump inhibitors (PPIs) in the standard of care of acute pancreatitis (AP), they are often prescribed in clinical practice, mainly for ulcer stress prophylaxis. In this systematic review and meta-analysis we evaluated the association between the use of PPIs in the management of AP and various clinical outcomes. We conducted the systematic research in six databases without restrictions on January 24th, 2022. We investigated adult patient with AP, who were treated with PPI compared to conventional therapy. The pooled odds ratios, mean differences, and corresponding 95% confidence intervals were calculated with random effect model. We included six RCTs and three cohort studies, consisting of 28,834 patients. We found a significant decrease in the rate of pancreatic pseudocyst formation in patients who received PPI treatment. PPI use was associated with a higher risk of GI bleeding, however this finding could be due to the patients' comorbid conditions. We found no significant difference in the rates of 7-day mortality, length of hospital stay, and acute respiratory distress syndrome between the groups. The available data on this topic are limited; therefore, further well designed RCTs are needed to evaluate the potential benefits and adverse effects of PPIs in AP.

Synergistic effects of agonists and two-pore-domain potassium channels on secretory responses of human pancreatic duct cells Capan-1

Mechanisms of synergistic agonist stimulation and modulation of the electrochemical driving force for anion secretion are still not fully explored in human pancreatic duct epithelial cells. The first objective of this study was therefore to test whether combined agonist stimulation augments anion transport responses in the Capan-1 monolayer model of human pancreatic duct epithelium. The second objective was to test the influence of H⁺,K⁺-ATPase inhibition on anion transport in Capan-1 monolayers. The third objective was to analyze the expression and function of K⁺ channels in Capan-1, which could support anion secretion and cooperate with H⁺,K⁺-ATPases in pH and potassium homeostasis. The human pancreatic adenocarcinoma cell line Capan-1 was cultured conventionally or as polarized monolayers that were analyzed by Ussing chamber electrophysiological recordings. Single-cell intracellular calcium was assayed with Fura-2. mRNA isolated from Capan-1 was analyzed by use of the nCounter assay or RT-PCR. Protein expression was assessed by immunofluorescence and western blot analyses. Combined stimulation with different physiological agonists enhanced anion transport responses compared to single agonist stimulation. The responsiveness of Capan-1 cells to histamine was also revealed in these experiments. The H⁺,K⁺-ATPase inhibitor omeprazole reduced carbachol- and riluzole-induced anion transport responses. Transcript analyses revealed abundant TASK-2, TWIK-1, TWIK-2, TASK-5, K_Ca3.1, and KCNQ1 mRNA expression. KCNE1 mRNA and TREK-1, TREK-2, TASK-2, and KCNQ1 protein expression were also shown. This study shows that the Capan-1 model recapitulates key physiological aspects of a bicarbonate-secreting epithelium and constitutes a valuable model for functional studies on human pancreatic duct epithelium.

Long-Term Outcomes in Patients with Post-Bulbar Ulcer Bleeding Compared to Bulbar Ulcer Bleeding in the Duodenum

BACKGROUND

Duodenal ulcers are classified into bulbar and post-bulbar ulcers. The aim of this study is to compare the long-term outcomes of patients with post-bulbar ulcer bleeding and those with bulbar ulcer bleeding.

METHODS

A total of 272 patients with hemorrhagic duodenal ulcers requiring hospitalization were included. Their medical records were retrospectively reviewed.

RESULTS

All patients were categorized as bulbar or post-bulbar bleeding ulcer groups. The post-bulbar ulcer group had more patients of advanced age, concurrent malignancy, diabetes mellitus, hypertension, cirrhosis, and chronic kidney disease undergoing hemodialysis. We performed long-term follow-up for an average of 2.6 years. The mortality rate during the follow-up period in the post-bulbar ulcer group was significantly higher than that in the bulbar ulcer group (p < 0.001). The PNED score was a better predictor of 30-day mortality compared to the complete Rockall score and the Glasgow-Blatchford Score. Predictors of mortality were evaluated using a Cox proportional hazards regression model. In multivariate analysis, post-bulbar ulcer, concurrent malignancy, cirrhosis, antiplatelet/anticoagulant use, and transfusion were significant predictors of mortality.

CONCLUSIONS

Patients with post-bulbar ulcers have a poorer prognosis than those with bulbar ulcers. After the diagnosis of hemorrhagic post-bulbar duodenal ulcer, close follow-up is necessary.

The Non-Gastric H+/K+ ATPase (ATP12A) Is Expressed in Mammalian Spermatozoa

H⁺/K⁺ ATPase Type 2 is an heteromeric membrane protein involved in cation transmembrane transport and consists of two subunits: a specific α subunit (ATP12A) and a non-specific β subunit. The aim of this study was to demonstrate the presence and establish the localization of ATP12A in spermatozoa from Bubalus bubalis, Bos taurus and Ovis aries. Immunoblotting revealed, in all three species, a major band (100 kDa) corresponding to the expected molecular mass. The ATP12A immunolocalization pattern showed, consistently in the three species, a strong signal at the acrosome. These results, described here for the first time in spermatozoa, are consistent with those observed for the β₁ subunit of Na⁺/K⁺ ATPase, suggesting that the latter may assemble with the α subunit to produce a functional ATP12A dimer in sperm cells. The above scenario appeared to be nicely supported by 3D comparative modeling and interaction energy calculations. The expression of ATP12A during different stages of bovine sperm maturation progressively increased, moving from epididymis to deferent ducts. Based on overall results, we hypothesize that ATP12A may play a role in acrosome reactions. Further studies will be required in order to address the functional role of this target protein in sperm physiology.

Proton Pump Inhibitors Were Associated With Reduced Pseudocysts in Acute Pancreatitis: A Multicenter Cohort Study

Background: Acute pancreatitis (AP) is a systemic inflammatory disorder with a wide spectrum of clinical symptoms that can range from mild to severe. Previous preclinical study results suggest that proton pump inhibitors (PPIs) can inhibit exocrine pancreatic secretion and exert anti-inflammatory properties, which might in turn improve the outcome of AP.

Aim: We conducted this multicenter, retrospective cohort study to investigate the potential effects of PPIs on the mortality, and total duration of hospital stay and local complication occurrence of patients with AP.

Methods: A total of 858 patients with AP were included. All patients presented to the hospital within 48 h of symptom onset and were divided into the following two groups: patients who were treated with PPIs (n = 684) and those not treated with PPIs (n = 174). We used propensity score matching (PSM) analysis to reduce confounding bias before comparing the outcomes between the two groups.

Results: Before PSM analysis, there were significant differences in a number of parameters between the two groups, including age, sex, hematocrit, blood urea nitrogen, peritonitis signs, Ranson’s score, and Acute Physiology Chronic Health Evaluation II score and organ failure occurrence. Before PSM, the PPIs group had a higher rate of mortality than the control group [RR = 1.065; 95% confidence ratio (CI) 1.045–1.086; p = 0.001]. After PSM, there was no significant difference in mortality (RR = 1.009; 95% CI, 0.999–1.019; p = 0.554) or total hospital stay (p = 0.856), although the PPIs group had a lower occurrence of pancreatic pseudocyst (RR = 0.416; 95% CI 0.221–0.780; p = 0.005).

Conclusion: This study showed that PPIs therapy was not associated with reduced mortality or total hospital stay, but was associated with a reduction in the occurrence of pseudocysts in patients with acute pancreatitis.

Associations with pancreatic exocrine insufficiency: An United Kingdom single-centre study

BACKGROUND

Pancreatic exocrine insufficiency (PEI) is said to be associated with numerous conditions both within and outside the gastrointestinal (GI) system. The majority of research has been concerned with conditions that reduce the volume of functioning pancreatic tissue or prevent adequate drainage to the small bowel, such as chronic pancreatitis, cystic fibrosis, pancreatic cancer and pancreatic resection. However, the evidence base supporting an association with extra-pancreatic conditions, such as coeliac disease, diabetes mellitus and congestive cardiac failure, is heterogeneous.

AIM

To strengthen the evidence base by studying all previously reported associations with PEI in a large cohort of outpatients.

METHODS

A single-centre retrospective study was performed. General gastroenterology outpatients tested for PEI with faecal elastase-1 (FE1) were identified and information retrieved from the electronic patient record. PEI was defined as FE1 < 200 μg/g. Patients already taking pancreatic enzyme replacement therapy were excluded. Multiple imputation was used to handle missing data. Univariable logistic regression was used to study which presenting symptoms predicted PEI. Multivariable logistic regression was used to explore the relationship between all previously reported associations and PEI.

RESULTS

Of 1027 patients were included. 182 patients (17.7%) were diagnosed with PEI. Steatorrhoea [odds ratios (OR): 2.51, 95% confidence intervals (CI): 1.58-3.98] and weight loss (OR: 1.49, 95%CI: 1.08-2.06) were the only presenting symptoms that predicted PEI. Chronic pancreatitis (OR: 7.98, 95%CI: 3.95-16.15), pancreatic cancer (OR: 6.58, 95%CI: 1.67-25.98), upper GI surgery (OR: 2.62, 95%CI: 1.32-5.19), type 2 diabetes (OR: 1.84, 95%CI: 1.18-2.87), proton pump inhibitor therapy (OR: 1.87, 95%CI: 1.25-2.80) and Asian ethnicity (OR: 2.11, 95%CI: 1.30-3.42) were significantly associated with PEI in the multivariable analysis. None of the other historically reported associations with PEI were significant after adjustment for the other variables included in our multivariable analysis.

CONCLUSION

PEI is common in patients with chronic pancreatitis, pancreatic cancer, upper GI surgery and type 2 diabetes. Proton pump inhibitor therapy may also be associated with PEI or a false positive FE1.

Performance of the faecal immunochemical test for the detection of colorectal neoplasms and the role of proton pump inhibitors in their diagnostic accuracy

AIM

The faecal immunochemical test (FIT) is currently utilized in both symptomatic and screening populations, but little is known about factors that affect its performance. For example, proton pump inhibitor (PPI) therapy has been purported to increase false negative rates. This has significant implications given the extent of PPI prescriptions. The aim of this work was to evaluate the performance of the FIT for the detection of colorectal neoplasms and the impact of PPI therapy on its diagnostic accuracy.

METHOD

Symptomatic patients referred on the suspected cancer pathway and those on polyp surveillance between 2015 and 2019 were approached to participate. Estimates of the accuracy of FIT at different cut-off levels in diagnosing colorectal neoplasms were made. Logistic regression was used to assess the effect of PPIs on the FIT results.

RESULTS

A total of 667 participants were eligible for the final analysis. At a cut-off of 10 μg/g faeces, the overall sensitivity and specificity of FIT for the detection of colorectal cancer (CRC) was 0.85 (95% CI 0.71-0.94) and 0.81 (95% CI 0.78-0.84), respectively. For the detection of advanced neoplasia, the sensitivity was 0.70 (95% CI 0.58-0.79) and the specificity was 0.83 (95% CI 0.80-0.86). At higher thresholds, the sensitivity steadily declined whilst specificity increased. PPI therapy did not have a significant effect on performance of the FIT.

CONCLUSION

FIT is a good rule-out test for the detection of CRC and advanced neoplasia at lower thresholds. PPI therapy does not appear to have an effect on its diagnostic performance.

Acute pancreatitis associated with duodenal obstruction induced by groove pancreatitis: A case report

RATIONALE

Groove pancreatitis (GP) is a rare form of chronic pancreatitis. Since GP presents with nonspecific symptoms, it can be challenging to diagnose. Duodenal obstruction is often caused by malignant diseases; however, when associated with acute pancreatitis, it is rarely induced by groove pancreatitis.

PATIENTS CONCERNS

A 56-year-old man who presented with acute pancreatitis complained of recurrent upper abdominal discomfort. His concomitant symptoms included abdominal pain, postprandial nausea, and vomiting. Contrast-enhanced computed tomography (CT) of the abdomen showed thickening of the duodenum wall. Gastrointestinal radiographs and upper gastrointestinal endoscopy showed an obstruction of the descending duodenum.

DIAGNOSIS

The pathologic diagnosis was groove pancreatitis.

INTERVENTIONS

The patient underwent gastrojejunostomy to relieve the obstruction.

OUTCOMES

The patient had an uneventful recovery with no complications.

LESSONS

Groove pancreatitis should be considered in the differential diagnosis of patients presenting with acute pancreatitis and duodenal obstruction. These data can help to make a precise diagnosis and develop an appropriate treatment plan.

Exploring the Effect of Esomeprazole on Gastric and Duodenal Fluid Volumes and Absorption of Ritonavir

Proton-pump inhibitors (PPIs), frequently prescribed to lower gastric acid secretion, often exert an effect on the absorption of co-medicated drug products. A previous study showed decreased plasma levels of the lipophilic drug ritonavir after co-administration with the PPI Nexium (40 mg esomeprazole), even though duodenal concentrations were not affected. The present study explored if a PPI-induced decrease in gastrointestinal (GI) fluid volume might contribute to the reduced absorption of ritonavir. In an exploratory cross-over study, five volunteers were given a Norvir tablet (100 mg ritonavir) orally, once without PPI pre-treatment and once after a three-day pre-treatment with the PPI esomeprazole. Blood samples were collected for eight hours to assess ritonavir absorption and magnetic resonance imaging (MRI) was used to determine the gastric and duodenal fluid volumes during the first three hours after administration of the tablet. The results confirmed that PPI intake reduced ritonavir plasma concentrations by 40%. The gastric residual volume and gastric fluid volume decreased by 41% and 44% respectively, while the duodenal fluid volume was reduced by 33%. These data suggest that the PPI esomeprazole lowers the available fluid volume for dissolution, which may limit the amount of ritonavir that can be absorbed. Although additional factors may play a role, the effect of PPI intake on the GI fluid volume should be considered when simulating the absorption of poorly soluble drugs like ritonavir in real-life conditions.

Pantoprazole, a proton-pump inhibitor, impairs human sperm motility and capacitation in vitro

BACKGROUND

The effects of PPIs on human sperm fertilizing capacity were poorly investigated although these drugs are widely over-used. Two publications retrospectively studied relationships between any PPI intake and sperm parameters from patients consulting at infertility clinics, but the conclusions of these reports were contradictory. Only two reports investigated the effects of lansoprazole and omeprazole on sperm motility and found lansoprazole to be deleterious and omeprazole to be neutral for sperm motility. The inconsistency of the PPI effect in the previous reports emphasizes the need for more basic research on human spermatozoa, taking into account the hypothesis that the different PPI drugs may have different effects on sperm physiology.

OBJECTIVES

Do PPIs, which are among the most widely sold drug in the word, impact negatively human sperm capacitation and sperm motility?

MATERIALS AND METHODS

The effects of PPIs on human sperm maturation and motility were analyzed by CASA, flow cytometry, and Western blot.

RESULTS

We tested the impact of 6 different PPIs on human sperm motility and capacitation. We showed that pantoprazole, but not the other PPIs, decreased sperm progressive motility and capacitation-induced sperm hyperactivation. We therefore investigated further the effects of pantoprazole on sperm capacitation, and we observed that it had a significant deleterious effect on the capacitation-induced hyperpolarization of the membrane potential and capacitation-associated protein phosphorylation.

DISCUSSION AND CONCLUSION

Our results indicate that exposure to pantoprazole has an adverse effect on the physiological competence of human spermatozoa. As the capacitation process takes place within the female tract, our results suggest that PPIs intake by the female partner may impair in vivo sperm maturation and possibly fertilization. Moreover, the absence of adverse effect by PPIs on mouse sperm emphasizes the need to develop reprotox assays using human material to better assess the effects of medication intake on sperm physiology.

H+/K+ATPase Expression in the Larynx of Laryngopharyngeal Reflux and Laryngeal Cancer Patients

OBJECTIVES

The gastric H+/K+ ATPase proton pump has previously been shown to be expressed in the human larynx, however its contribution to laryngopharyngeal reflux (LPR) signs, symptoms and associated diseases such as laryngeal cancer is unknown. Proton pump expression in the larynx of patients with LPR and laryngeal cancer was investigated herein. A human hypopharyngeal cell line expressing the proton pump was generated to investigate its effects.

STUDY DESIGN

In-vitro translational.

METHODS

Laryngeal biopsies were obtained from three LPR and eight LSCC patients. ATP4A, ATP4B and HRPT1 were assayed via qPCR. Human hypopharyngeal FaDu cell lines stably expressing proton pump were created using lentiviral transduction and examined via transmission electron microscopy and qPCR for genes associated with inflammation or laryngeal cancer.

RESULTS

Expression of ATP4A and ATP4B was detected in 3/3 LPR, 4/8 LSCC-tumor and 3/8 LSCC-adjacent specimens. Expression of ATP4A and ATP4B in FaDu elicited mitochondrial damage and expression of IL1B, PTGS2, and TNFA (P < .0001); expression of ATP4B alone did not.

CONCLUSIONS

Gastric proton pump subunits are expressed in the larynx of LPR and LSCC patients. Mitochondrial damage and changes in gene expression observed in cells expressing the full proton pump, absent in those expressing a single subunit, suggest that acid secretion by functional proton pumps expressed in upper airway mucosa may elicit local cell and molecular changes associated with inflammation and cancer.

LEVEL OF EVIDENCE

NA Laryngoscope, 131:130-135, 2021.

Proton Pump Inhibitors Reduce Pancreatic Adenocarcinoma Progression by Selectively Targeting H+, K+-ATPases in Pancreatic Cancer and Stellate Cells

Pancreatic duct cells are equipped with acid/base transporters important for exocrine secretion. Pancreatic ductal adenocarcinoma (PDAC) cells may utilize such transporters to acidify extracellular tumor microenvironment, creating a niche favoring cell proliferation, fibrosis and resistance to chemotherapy-all contributing to the notoriously bad prognosis of this disease. Here, we report that gastric and non-gastric H⁺, K⁺-ATPases (coded by ATP4A and ATP12A) are overexpressed in human and murine pancreatic cancer and that we can target them specifically with proton pump inhibitors (PPIs) and potassium-competitive acid blockers (P-CABs) in in vitro models of PDAC. Focusing on pantoprazole, we show that it significantly reduced human cancer cell proliferation by inhibiting cellular H⁺ extrusion, increasing K⁺ conductance and promoting cyclin D1-dependent cell cycle arrest and preventing STAT3 activation. Pantoprazole also decreased collagen secretion from pancreatic stellate cells. Importantly, in vivo studies show that pantoprazole treatment of tumor-bearing mice reduced tumor size, fibrosis and expression of angiogenic markers. This work provides the first evidence that H⁺, K⁺-ATPases contribute to PDAC progression and that these can be targeted by inhibitors of these pumps, thus proving a promising therapeutic strategy.

The Clinician's Guide to Proton Pump Inhibitor Related Adverse Events

A substantial volume of literature exists linking proton pump inhibitor (PPI) use with a multitude of serious adverse events. There is uncertainty, however, over whether these associations are clinically important. Excessive concern about PPI-related adverse events may leave patients at risk of harm by leaving acid-related upper gastrointestinal disease untreated. Conversely, the risk of treatments may outweigh the benefits if any of the purported adverse events are directly caused by PPI use; this is of particular concern where indications for PPI use are not present. In this paper, we review the studies which have reported associations between adverse events and PPI use, discuss the proposed mechanisms of action, grade the confidence in whether these associations are truly causal, and provide advice regarding balancing the benefits of PPI use against their possible harms.

Portrait of Tissue-Specific Coexpression Networks of Noncoding RNAs (miRNA and lncRNA) and mRNAs in Normal Tissues

Genes that encode proteins playing a role in more than one biological process are frequently dependent on their tissue context, and human diseases result from the altered interplay of tissue- and cell-specific processes. In this work, we performed a computational approach that identifies tissue-specific co-expression networks by integrating miRNAs, long-non-coding RNAs, and mRNAs in more than eight thousands of human samples from thirty normal tissue types. Our analysis (1) shows that long-non coding RNAs and miRNAs have a high specificity, (2) confirms several known tissue-specific RNAs, and (3) identifies new tissue-specific co-expressed RNAs that are currently still not described in the literature. Some of these RNAs interact with known tissue-specific RNAs or are crucial in key cancer functions, suggesting that they are implicated in tissue specification or cell differentiation.

Treatment of walled-off pancreatic necrosis

PURPOSE OF REVIEW

To review the current management of walled-off pancreatic necrosis (WOPN).

RECENT FINDINGS

The management of WOPN has evolved. Many collections do not require intervention and may resolve over time. Nutritional support and treatment of infection are two critical components of medical management. For collections requiring drainage, minimally invasive endoscopic therapies now play a primary role. Endoscopic transmural puncture with stent placement may provide access for drainage and decompression. More complex collections may require transluminal instrumentation with lavage, debridement, and necrosectomy. Concurrent pancreatic duct injuries including strictures, leaks, and disconnections are very common. Addressing the pancreatic ductal injury is a key component in the long-term success of management strategies. Providing high-level care for patients requires a multidisciplinary approach with providers specialized in the management of severe acute pancreatitis and associated complications.

SUMMARY

Minimally invasive management strategies improve the outcomes for patients with WOPN. Close follow-up, medical therapy, and nutritional support are required for most patients. Endoscopic transmural drainage and necrosectomy are the primary approaches for collections requiring intervention. Protocols for endoscopic drainage are being refined to reduce side effects and decrease the number of interventions required for resolution.

Genetic association and transcriptome integration identify contributing genes and tissues at cystic fibrosis modifier loci

Cystic Fibrosis (CF) exhibits morbidity in several organs, including progressive lung disease in all patients and intestinal obstruction at birth (meconium ileus) in ~15%. Individuals with the same causal CFTR mutations show variable disease presentation which is partly attributed to modifier genes. With >6,500 participants from the International CF Gene Modifier Consortium, genome-wide association investigation identified a new modifier locus for meconium ileus encompassing ATP12A on chromosome 13 (min p = 3.83x10(-10)); replicated loci encompassing SLC6A14 on chromosome X and SLC26A9 on chromosome 1, (min p<2.2x10(-16), 2.81x10(-11), respectively); and replicated a suggestive locus on chromosome 7 near PRSS1 (min p = 2.55x10(-7)). PRSS1 is exclusively expressed in the exocrine pancreas and was previously associated with non-CF pancreatitis with functional characterization demonstrating impact on PRSS1 gene expression. We thus asked whether the other meconium ileus modifier loci impact gene expression and in which organ. We developed and applied a colocalization framework called the Simple Sum (SS) that integrates regulatory and genetic association information, and also contrasts colocalization evidence across tissues or genes. The associated modifier loci colocalized with expression quantitative trait loci (eQTLs) for ATP12A (p = 3.35x10(-8)), SLC6A14 (p = 1.12x10(-10)) and SLC26A9 (p = 4.48x10(-5)) in the pancreas, even though meconium ileus manifests in the intestine. The meconium ileus susceptibility locus on chromosome X appeared shifted in location from a previously identified locus for CF lung disease severity. Using the SS we integrated the lung disease association locus with eQTLs from nasal epithelia of 63 CF participants and demonstrated evidence of colocalization with airway-specific regulation of SLC6A14 (p = 2.3x10(-4)). Cystic Fibrosis is realizing the promise of personalized medicine, and identification of the contributing organ and understanding of tissue specificity for a gene modifier is essential for the next phase of personalizing therapeutic strategies.

Two Novel Candidate Genes for Insulin Secretion Identified by Comparative Genomics of Multiple Backcross Mouse Populations

To identify novel disease genes for type 2 diabetes (T2D) we generated two backcross populations of obese and diabetes-susceptible New Zealand Obese (NZO/HI) mice with the two lean mouse strains 129P2/OlaHsd and C3HeB/FeJ. Subsequent whole-genome linkage scans revealed 30 novel quantitative trait loci (QTL) for T2D-associated traits. The strongest association with blood glucose [12 cM, logarithm of the odds (LOD) 13.3] and plasma insulin (17 cM, LOD 4.8) was detected on proximal chromosome 7 (designated Nbg7p, NZO blood glucose on proximal chromosome 7) exclusively in the NZOxC3H crossbreeding, suggesting that the causal gene is contributed by the C3H genome. Introgression of the critical C3H fragment into the genetic NZO background by generating recombinant congenic strains and metabolic phenotyping validated the phenotype. For the detection of candidate genes in the critical region (30-46 Mb), we used a combined approach of haplotype and gene expression analysis to search for C3H-specific gene variants in the pancreatic islets, which appeared to be the most likely target tissue for the QTL. Two genes, Atp4a and Pop4, fulfilled the criteria from our candidate gene approaches. The knockdown of both genes in MIN6 cells led to decreased glucose-stimulated insulin secretion, indicating a regulatory role of both genes in insulin secretion, thereby possibly contributing to the phenotype linked to Nbg7p In conclusion, our combined- and comparative-cross analysis approach has successfully led to the identification of two novel diabetes susceptibility candidate genes, and thus has been proven to be a valuable tool for the discovery of novel disease genes.

Colorectal cancer after negative colonoscopy in fecal immunochemical test-positive participants from a colorectal cancer screening program

Background and study aims  Colorectal cancer (CRC) risk after a positive fecal immunochemical test (FIT) and negative colonoscopy is unknown. We aimed to ascertain the cumulative incidence of post-colonoscopy colorectal cancer (PCCRC) and the manifestation of other lesions that could explain the test positivity in individuals with a negative colonoscopy in a population screening program. Patients and method  Observational study in participants from the first round of a CRC screening program (2010 - 2012) with positive-FIT (≥ 20 μg/g of feces) and negative colonoscopy (without neoplasia). A 42- to 76-month follow-up was performed searching in the National Health Service database and by a brief structured telephonic interview. Results  Of 2659 FIT-positive individuals who underwent colonoscopy, 811 (30.5 %) had a negative colonoscopy. Three PCCRC (0.4 %) were detected within 11 - 28 months and accelerated carcinogenesis was ruled out. Among those with normal colonoscopy, 32 (5 %) relevant lesions were detected at follow-up. One-third of them (11/32) were significant neoplasias: a gastric cancer, a small-bowel lymphoma, six advanced colorectal adenomas, and the three PCCRC. The 21 remaining lesions were inflammatory, vascular disorders, or non-advanced colorectal adenomas. Conclusions  The vast majority (95 %) of individuals did not present any subsequent lesion that could explain the FIT positivity. The very low incidence (0.4 %) and characteristics of PCCRC observed in our cohort reinforce the concept that, although a positive FIT preselects high risk individuals, a high quality colonoscopy is the paramount factor in preventing PCCRC. Improving quality standards of colonoscopy are required to strengthen the current CRC screening strategies.

Proton pump inhibitors reduce the accuracy of faecal immunochemical test for detecting advanced colorectal neoplasia in symptomatic patients

Background

The faecal immunochemical test (FIT) is used in colorectal cancer (CRC) screening and for the detection of advanced colorectal neoplasia (AN) in symptomatic patients, but its accuracy could be improved. Our objective was to assess the impact of proton pump inhibitors (PPI) on the accuracy of the FIT in the detection of AN, namely advanced colorectal adenoma and CRC.

Methods and findings

We performed a prospective study of 1002 individuals referred for a diagnostic colonoscopy at Bellvitge University Hospital from September 2011 through to October 2012. An exhaustive interview was performed by a gastroenterologist, prescription drug dispensing database was reviewed and the patient was given a FIT prior to colonoscopy. The positivity threshold of FIT used was ≥ 20 μg Hb/g feces and the main outcome was AN. AN was detected in 13.2% (133) of patients. The accuracy of FIT for detecting AN in the PPI users and non-PPI users were: sensitivity 43.0% vs 65.6%, P = 0.009; specificity 86.9% vs 92.3%, P = 0.010; and, predictive positive value 34.4% vs 55.5%, P = 0.007, respectively. In multivariate analysis, adjusting for potential confounders, PPIs were associated with false positives in AN detection by FIT (OR 1.63 CI 95% 1.02–2.59, P < 0.037). The ROC curve for the FIT in the detection of AN in the PPI users and non-PPI users was 0.68 (CI 95% 0.61–0.76) and 0.85 (CI 95% 0.79–0.90).

Conclusions

PPI therapy reduces the accuracy of FIT for detecting AN in symptomatic patients.

Association between Proton Pump Inhibitor Use and CNS Infection Risk: A Retrospective Cohort Study

This study investigated the incidence of central nervous system (CNS) infection following the use of proton pump inhibitors (PPIs). A retrospective cohort study was conducted in Taiwan by using data from the National Health Insurance Research Database. We identified and enrolled 16,241 patients with CNS infection who used PPIs (PPI users). The patients were individually propensity score matched (1:1) according to age, sex, hypertension, hyperlipidemia, Charlson comorbidity index (CCI), H2 blocker, non-steroidal anti-inflammatory drugs (NSAIDs), corticosteroid, and immunosuppressant use with 16,241 controls (PPI nonusers). A Cox proportional hazards model was used to estimate adjusted hazard ratio (aHR) for CNS infection in the PPI users and nonusers. After adjustment for other confounding factors, the incidence of CNS infection in the PPI users was 2.23-fold higher than that in the PPI nonusers (95% CI = 1.27⁻3.94). In addition, the PPI users exhibited a higher risk of CNS infection than the nonusers in the hypertension and CCI = 1 groups (aHR = 3.80, 95% CI = 1.40⁻10.32; aHR = 2.47, 95% CI = 1.07⁻5.70 in the PPI users and nonusers, respectively). In conclusions, according to these results, we concluded that the incidence of CNS infection was higher in the PPI users than in the nonusers.

Extracellular Acid-Base Balance and Ion Transport Between Body Fluid Compartments

Clinical assessment of acid-base disorders depends on measurements made in the blood, part of the extracellular compartment. Yet much of the metabolic importance of these disorders concerns intracellular events. Intracellular and interstitial compartment acid-base balance is complex and heterogeneous. This review considers the determinants of the extracellular fluid pH related to the ion transport processes at the interface of cells and the interstitial fluid, and between epithelial cells lining the transcellular contents of the gastrointestinal and urinary tracts that open to the external environment. The generation of acid-base disorders and the associated disruption of electrolyte balance are considered in the context of these membrane transporters. This review suggests a process of internal and external balance for pH regulation, similar to that of potassium. The role of secretory gastrointestinal epithelia and renal epithelia with respect to normal pH homeostasis and clinical disorders are considered. Electroneutrality of electrolytes in the ECF is discussed in the context of reciprocal changes in Cl^- or non Cl^- anions and [Formula: see text].

The Gut-Brain Axis, the Human Gut Microbiota and Their Integration in the Development of Obesity

Obesity is a global epidemic, placing socioeconomic strain on public healthcare systems, especially within the so-called Western countries, such as Australia, United States, United Kingdom, and Canada. Obesity results from an imbalance between energy intake and energy expenditure, where energy intake exceeds expenditure. Current non-invasive treatments lack efficacy in combating obesity, suggesting that obesity is a multi-faceted and more complex disease than previously thought. This has led to an increase in research exploring energy homeostasis and the discovery of a complex bidirectional communication axis referred to as the gut-brain axis. The gut-brain axis is comprised of various neurohumoral components that allow the gut and brain to communicate with each other. Communication occurs within the axis via local, paracrine and/or endocrine mechanisms involving a variety of gut-derived peptides produced from enteroendocrine cells (EECs), including glucagon-like peptide 1 (GLP1), cholecystokinin (CCK), peptide YY3-36 (PYY), pancreatic polypeptide (PP), and oxyntomodulin. Neural networks, such as the enteric nervous system (ENS) and vagus nerve also convey information within the gut-brain axis. Emerging evidence suggests the human gut microbiota, a complex ecosystem residing in the gastrointestinal tract (GIT), may influence weight-gain through several inter-dependent pathways including energy harvesting, short-chain fatty-acids (SCFA) signalling, behaviour modifications, controlling satiety and modulating inflammatory responses within the host. Hence, the gut-brain axis, the microbiota and the link between these elements and the role each plays in either promoting or regulating energy and thereby contributing to obesity will be explored in this review.

Substituted methoxybenzyl-sulfonyl-1H-benzo[d]imidazoles evaluated as effective H+/K+-ATPase inhibitors and anti-ulcer therapeutics

Efforts were made to synthesize a series of substituted methoxybenzyl-sulfonyl-1H-benzo[d]imidazole derivatives (8a-l) and investigate their anti-ulcer therapeutics. Prior to evaluating antiulcer potentials of 8a-l, a preliminary binding assay against H⁺/K⁺-ATPase from goat gastric mucosa was carried out, since it plays an important role in the ulcer development. In order to get more insight into the binding mode of the compounds to H⁺/K⁺-ATPase, a molecular docking study was carried out and the best binding affinities were unveiled. Many of the substituted methoxybenzyl-sulfonyl-1H-benzo[d]imidazole derivatives (8a-l) were active for the proposed activity. The key finding was that, least inhibitory constant (ki) values of 8a-l were found between 0.02 and 1.8 μM in the molecular docking study. Almost the same range was reflected/correlated in the H⁺/K⁺-ATPase inhibition assay (IC₅₀ 0.14-1.29 μM). Remarkably, compounds 8a-l showed a relative activity percentage range of 72-92%. Efficient HRBC membrane stabilization activity of 8a-l ensured the non-harm/safety and the suitability/alternative towards anti-ulcer therapy.

Paraduodenal pancreatitis as an uncommon cause of gastric outlet obstruction: A case report and review of the literature

•

Paraduodenal pancreatitis is a rare form of focal chronic or recurrent pancreatitis that can present as gastric outlet obstruction.

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Endoscopic ultrasound and fine needle aspiration biopsy provides the best diagnostic modality.

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Key histopathologic features include Brunner gland hyperplasia, myofibroblastic proliferation, spindle cells and foamy cells.

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Cross-sectional imaging demonstrates a fibrotic, sheet-like mass with cystic change between the duodenal wall and pancreatic head.

•

The optimal treatment for refractory symptoms is pancreaticoduodenectomy.

Introduction

Paraduodenal pancreatitis (PP) is an under-recognized form of focal chronic or recurrent pancreatitis. Since PP presents with non-specific symptoms and shares radiological and histopathological features with other entities, it can be challenging to diagnose.

Presentation of case report

Herein, a case of a 64 year-old Caucasian male with PP presenting with recurrent gastric outlet obstruction (GOO) is detailed. Over the course of two years, he underwent multiple balloon dilatations for symptom management. His diagnostic course was complicated by inconclusive and misleading biopsies.

Conclusion

PP can rarely present as GOO in otherwise asymptomatic patients. A preoperative pathologic diagnosis can be difficult to obtain, and in this case delayed definitive surgical management. The case is discussed in detail, and a concise review the current literature was undertaken.

A Review of the Novel Application and Potential Adverse Effects of Proton Pump Inhibitors

Proton pump inhibitors (PPIs) are known as a class of pharmaceutical agents that target H⁺/K⁺-ATPase, which is located in gastric parietal cells. PPIs are widely used in the treatment of gastric acid-related diseases including peptic ulcer disease, erosive esophagitis and gastroesophageal reflux disease, and so on. These drugs present an excellent safety profile and have become one of the most commonly prescribed drugs in primary and specialty care. Except for gastric acid-related diseases, PPIs can also be used in the treatment of Helicobacter pylori infection, viral infections, respiratory system diseases, cancer and so on. Although PPIs are mainly used short term in patients with peptic ulcer disease, nowadays these drugs are increasingly used long term, and frequently for a lifetime, for instance in patients with typical or atypical symptoms of gastroesophageal reflux disease and in NSAID or aspirin users at risk of gastrotoxicity and related complications including hemorrhage, perforation and gastric outlet obstruction. Long-term use of PPIs may lead to potential adverse effects, such as osteoporotic fracture, renal damage, infection (pneumonia and clostridium difficile infection), rhabdomyolysis, nutritional deficiencies (vitamin B12, magnesium and iron), anemia and thrombocytopenia. In this article, we will review some novel uses of PPIs in other fields and summarize the underlying adverse reactions.

Bicarbonate-rich fluid secretion predicted by a computational model of guinea-pig pancreatic duct epithelium

KEY POINTS

The ductal system of the pancreas secretes large volumes of alkaline fluid containing HCO₃^- concentrations as high as 140 mm during hormonal stimulation. A computational model has been constructed to explore the underlying ion transport mechanisms. Parameters were estimated by fitting the model to experimental data from guinea-pig pancreatic ducts. The model was readily able to secrete 140 mm HCO₃^- . Its capacity to do so was not dependent upon special properties of the cystic fibrosis transmembrane conductance regulator (CFTR) anion channels and solute carrier family 26 member A6 (SLC26A6) anion exchangers. We conclude that the main requirement for secreting high HCO₃^- concentrations is to minimize the secretion of Cl^- ions. These findings help to clarify the mechanism responsible for pancreatic HCO₃^- secretion, a vital process that prevents the formation of protein plugs and viscous mucus in the ducts, which could otherwise lead to pancreatic disease.

ABSTRACT

A computational model of guinea-pig pancreatic duct epithelium was developed to determine the transport mechanism by which HCO₃^- ions are secreted at concentrations in excess of 140 mm. Parameters defining the contributions of the individual ion channels and transporters were estimated by least-squares fitting of the model predictions to experimental data obtained from isolated ducts and intact pancreas under a range of experimental conditions. The effects of cAMP-stimulated secretion were well replicated by increasing the activities of the basolateral Na⁺ -HCO₃^- cotransporter (NBC1) and apical Cl^- /HCO₃^- exchanger (solute carrier family 26 member A6; SLC26A6), increasing the basolateral K⁺ permeability and apical Cl^- and HCO₃^- permeabilities (CFTR), and reducing the activity of the basolateral Cl^- /HCO₃^- exchanger (anion exchanger 2; AE2). Under these conditions, the model secreted ∼140 mm HCO₃^- at a rate of ∼3 nl min^-1  mm^-2 , which is consistent with experimental observations. Alternative 1:2 and 1:1 stoichiometries for Cl^- /HCO₃^- exchange via SLC26A6 at the apical membrane were able to support a HCO₃^- -rich secretion. Raising the HCO₃^- /Cl^- permeability ratio of CFTR from 0.4 to 1.0 had little impact upon either the secreted HCO₃^- concentration or the volume flow. However, modelling showed that a reduction in basolateral AE2 activity by ∼80% was essential in minimizing the intracellular Cl^- concentration following cAMP stimulation and thereby maximizing the secreted HCO₃^- concentration. The addition of a basolateral Na⁺ -K⁺ -2Cl^- cotransporter (NKCC1), assumed to be present in rat and mouse ducts, raised intracellular Cl^- and resulted in a lower secreted HCO₃^- concentration, as is characteristic of those species. We conclude therefore that minimizing the driving force for Cl^- secretion is the main requirement for secreting 140 mm HCO₃^- .

Omeprazole suppressed plasma magnesium level and duodenal magnesium absorption in male Sprague-Dawley rats

Hypomagnesemia is the most concerned side effect of proton pump inhibitors (PPIs) in chronic users. However, the mechanism of PPIs-induced systemic Mg²⁺ deficit is currently unclear. The present study aimed to elucidate the direct effect of short-term and long-term PPIs administrations on whole body Mg²⁺ homeostasis and duodenal Mg²⁺ absorption in rats. Mg²⁺ homeostasis was studied by determining the serum Mg²⁺ level, urine and fecal Mg²⁺ excretions, and bone and muscle Mg²⁺ contents. Duodenal Mg²⁺ absorption as well as paracellular charge selectivity were studied. Our result showed that gastric and duodenal pH markedly increased in omeprazole-treated rats. Omeprazole significantly suppressed plasma Mg²⁺ level, urinary Mg²⁺ excretion, and bone and muscle Mg²⁺ content. Thus, omeprazole induced systemic Mg²⁺ deficiency. By using Ussing chamber techniques, it was shown that omeprazole markedly suppressed duodenal Mg²⁺ channel-driven and Mg²⁺ channel-independent Mg²⁺ absorptions and cation selectivity. Inhibitors of mucosal HCO₃^- secretion significantly increased duodenal Mg²⁺ absorption in omeprazole-treated rats. We therefore hypothesized that secreted HCO₃^- in duodenum decreased luminal proton, this impeded duodenal Mg²⁺ absorption. Higher plasma total 25-OH vitamin D, diuresis, and urine PO₄^3- were also demonstrated in hypomagnesemic rats. As a compensatory mechanism for systemic Mg²⁺ deficiency, the expressions of duodenal transient receptor potential melastatin 6 (TRPM6), cyclin M4 (CNNM4), claudin (Cldn)-2, Cldn-7, Cldn-12, and Cldn-15 proteins were enhanced in omeprazole-treated rats. Our findings support the potential role of duodenum on the regulation of Mg²⁺ homeostasis.

Goblet Cell Hyperplasia Requires High Bicarbonate Transport To Support Mucin Release

Goblet cell hyperplasia, a feature of asthma and other respiratory diseases, is driven by the Th-2 cytokines IL-4 and IL-13. In human bronchial epithelial cells, we find that IL-4 induces the expression of many genes coding for ion channels and transporters, including TMEM16A, SLC26A4, SLC12A2, and ATP12A. At the functional level, we find that IL-4 enhances calcium- and cAMP-activated chloride/bicarbonate secretion, resulting in high bicarbonate concentration and alkaline pH in the fluid covering the apical surface of epithelia. Importantly, mucin release, elicited by purinergic stimulation, requires the presence of bicarbonate in the basolateral solution and is defective in cells derived from cystic fibrosis patients. In conclusion, our results suggest that Th-2 cytokines induce a profound change in expression and function in multiple ion channels and transporters that results in enhanced bicarbonate transport ability. This change is required as an important mechanism to favor release and clearance of mucus.

Prescription drugs associated with false-positive results when using faecal immunochemical tests for colorectal cancer screening

BACKGROUND

The most common side effect in population screening programmes is a false-positive result which leads to unnecessary risks and costs.

AIMS

To identify factors associated with false-positive results in a colorectal cancer screening programme with the faecal immunochemical test (FIT).

METHODS

Cross-sectional study of 472 participants with a positive FIT who underwent colonoscopy for confirmation of diagnosis between 2013 and 2014. A false-positive result was defined as having a positive FIT (≥20μg haemoglobin per gram of faeces) and follow-up colonoscopy without intermediate/high-risk lesions or cancer.

RESULTS

Women showed a two-fold increased likelihood of a false-positive result compared with men (adjusted OR, 2.3; 95%CI, 1.5-3.4), but no female-specific factor was identified. The other variables associated with a false-positive result were successive screening (adjusted OR, 1.5; 95%CI, 1.0-2.2), anal disorders (adjusted OR, 3.1; 95%CI, 2.1-4.5) and the use of proton pump inhibitors (adjusted OR, 1.8; 95%CI, 1.1-2.9). Successive screening and proton pump inhibitor use were associated with FP in men. None of the other drugs were related to a false-positive FIT.

CONCLUSION

Concurrent use of proton pump inhibitors at the time of FIT might increase the likelihood of a false-positive result. Further investigation is needed to determine whether discontinuing them could decrease the false-positive rate.

The adenosine A2B receptor is involved in anion secretion in human pancreatic duct Capan-1 epithelial cells

Adenosine modulates a wide variety of biological processes via adenosine receptors. In the exocrine pancreas, adenosine regulates transepithelial anion secretion in duct cells and is considered to play a role in acini-to-duct signaling. To identify the functional adenosine receptors and Cl⁻ channels important for anion secretion, we herein performed experiments on Capan-1, a human pancreatic duct cell line, using open-circuit Ussing chamber and gramicidin-perforated patch-clamp techniques. The luminal addition of adenosine increased the negative transepithelial potential difference (V_te) in Capan-1 monolayers with a half-maximal effective concentration value of approximately 10 μM, which corresponded to the value obtained on whole-cell Cl⁻ currents in Capan-1 single cells. The effects of adenosine on V_te, an equivalent short-circuit current (I_sc), and whole-cell Cl⁻ currents were inhibited by CFTRinh-172, a cystic fibrosis transmembrane conductance regulator (CFTR) Cl⁻ channel inhibitor. The adenosine A_2B receptor agonist, BAY 60-6583, increased I_sc and whole-cell Cl⁻ currents through CFTR Cl⁻ channels, whereas the A_2A receptor agonist, CGS 21680, had negligible effects. The A_2B receptor antagonist, PSB 603, inhibited the response of I_sc to adenosine. Immunohistochemical analysis showed that the A_2A and A_2B receptors colocalized with Ezrin in the luminal membranes of Capan-1 monolayers and in rat pancreatic ducts. Adenosine elicited the whole-cell Cl⁻ currents in guinea pig duct cells. These results demonstrate that luminal adenosine regulates anion secretion by activating CFTR Cl⁻ channels via adenosine A_2B receptors on the luminal membranes of Capan-1 cells. The present study endorses that purinergic signaling is important in the regulation of pancreatic secretion.

ATP release, generation and hydrolysis in exocrine pancreatic duct cells

Extracellular adenosine triphosphate (ATP) regulates pancreatic duct function via P2Y and P2X receptors. It is well known that ATP is released from upstream pancreatic acinar cells. The ATP homeostasis in pancreatic ducts, which secrete bicarbonate-rich fluid, has not yet been examined. First, our aim was to reveal whether pancreatic duct cells release ATP locally and whether they enzymatically modify extracellular nucleotides/sides. Second, we wished to explore which physiological and pathophysiological factors may be important in these processes. Using a human pancreatic duct cell line, Capan-1, and online luminescence measurement, we detected fast ATP release in response to pH changes, bile acid, mechanical stress and hypo-osmotic stress. ATP release following hypo-osmotic stress was sensitive to drugs affecting exocytosis, pannexin-1, connexins, maxi-anion channels and transient receptor potential cation channel subfamily V member 4 (TRPV4) channels, and corresponding transcripts were expressed in duct cells. Direct stimulation of intracellular Ca(2+) and cAMP signalling and ethanol application had negligible effects on ATP release. The released ATP was sequentially dephosphorylated through ecto-nucleoside triphosphate diphosphohydrolase (NTPDase2) and ecto-5'-nucleotidase/CD73 reactions, with respective generation of adenosine diphosphate (ADP) and adenosine and their maintenance in the extracellular medium at basal levels. In addition, Capan-1 cells express counteracting adenylate kinase (AK1) and nucleoside diphosphate kinase (NDPK) enzymes (NME1, 2), which contribute to metabolism and regeneration of extracellular ATP and other nucleotides (ADP, uridine diphosphate (UDP) and uridine triphosphate (UTP)). In conclusion, we illustrate a complex regulation of extracellular purine homeostasis in a pancreatic duct cell model involving: ATP release by several mechanisms and subsequent nucleotide breakdown and ATP regeneration via counteracting nucleotide-inactivating and nucleotide-phosphorylating ecto-enzymes. We suggest that extracellular ATP homeostasis in pancreatic ducts may be important in pancreas physiology and potentially in pancreas pathophysiology.