Summary: Background: Vonoprazan (V), a potassium‐competitive acid blocker, has a more durable acid‐inhibitory effect as compared with standard‐dose proton pump inhibitors (PPIs) but has not been compared with 2‐4 times higher daily PPI doses administered in two divided doses.Aims: To evaluate the acid‐inhibitory effect of V 10/20 mg once‐daily (OD; V10/V20) vs rabeprazole (R) 10/20 mg twice‐daily (BID; R20/R40) in healthy Japanese volunteers.Methods: This multicentre, randomised, open‐label, two‐period, crossover study compared V10 or V20 vs R20, or V20 vs R40 using three cohorts of 10 healthy Japanese adults. Within each cohort, subjects were randomised to receive V or R for 7 days and, following a washout period ≥7 days, the other treatment for 7 days. On day 6 of each period, 24‐hours multichannel gastric impedance‐pH monitoring was performed. Percent times pH ≥ 3, ≥4 and ≥5 (pH 3, 4 and 5 holding time ratios [HTRs]) in 24 hours were evaluated as primary pharmacodynamic endpoints.Results: Acid‐inhibitory effect (24‐hours pH 3 HTR) of V20 was greater than those of R20 (91.0% vs 65.3%; P = .0049) and R40 (98.5% vs 85.9%; P = .0073). Similar results were obtained for 24‐hours pH 4 and 5 HTRs. V20 also achieved greater nocturnal pH 4 (91.5% vs 73.2%; P = .0319) and 5 HTRs (78.8% vs 62.2%; P = .0325) as compared with R40. One subject (20%) developed diarrhoea while receiving R40 which was considered treatment‐related.Conclusions: Compared with 2‐4 times the standard daily dose of R, V20 exerts a more potent and durable acid‐inhibitory effect. Trial identifier: UMIN000022198 (www.umin.ac.jp/ctr/index.htm).

The underlying causes of heartburn, characteristic symptom of gastroesophageal reflux disease (GERD), remain incompletely understood. Superficial afferent innervation of the esophageal mucosa in nonerosive reflux disease (NERD) may drive nociceptive reflux perception, but its acid-sensing role has not yet been established. Transient receptor potential vanilloid subfamily member-1 (TRPV1), transient receptor potential melastatin 8 (TRPM8), and acid-sensing ion channel 3 (ASIC3) are regulators of sensory nerve activity and could be important reflux-sensing receptors within the esophageal mucosa. We characterized TRPV1, TRPM8, and ASIC3 expression in esophageal mucosa of patients with GERD. We studied 10 patients with NERD, 10 with erosive reflux disease (ERD), 7 with functional heartburn (FH), and 8 with Barrett’s esophagus (BE). Biopsies obtained from the distal esophageal mucosa were costained with TRPV1, TRPM8, or ASIC3, and CGRP, CD45, or E-cadherin. RNA expression of TRPV1, TRPM8, and ASIC3 was assessed using qPCR. Patients with NERD had significantly increased expression of TRPV1 on superficial sensory nerves compared with ERD (P = 0.028) or BE (P = 0.017). Deep intrapapillary nerve endings did not express TRPV1 in all phenotypes studied. ASIC3 was exclusively expressed on epithelial cells most significantly in patients with NERD and ERD (P ≤0.0001). TRPM8 was expressed on submucosal CD45+ leukocytes. Superficial localization of TRPV1-immunoreactive nerves in NERD, and increased ASIC3 coexpression on epithelial cells in NERD and ERD, suggests a mechanism for heartburn sensation. Esophageal epithelial cells may play a sensory role in acid reflux perception and act interdependently with TRPV1-expressing mucosal nerves to augment hypersensitivity in patients with NERD, raising the enticing possibility of topical antagonists for these ion channels as a therapeutic option. NEW & NOTEWORTHY We demonstrate for the first time that increased pain perception in patients with nonerosive reflux disease likely results from expression of acid-sensitive channels on superficial mucosal afferents and esophageal epithelial cells, raising the potential for topical therapy.

Summary: Background: Supragastric belching (SGB) has a significant behavioural component. We recently used cognitive behavioural therapy (CBT) to treat SGB. We demonstrated that CBT significantly reduces symptoms and improves quality of life in 50% of patients who had completed treatment.Aims: To investigate factors associated with successful CBT for SGB and to assess symptoms 6‐12 months after completion of CBTMethods: Records of 39 patients who had completed the CBT protocol were analysed. Per cent pre‐ to post‐treatment change in symptoms was assessed using a visual analogue scale (VAS) score. We evaluated the association between ‘pre‐treatment’ factors and ‘during‐treatment’ factors, and symptomatic outcomes. Symptoms were also assessed 6‐12 months after treatment.Results: From ‘pre‐treatment factors’, a lower number of SGBs (P < .01) and lower hypervigilance score (P < .04) were significantly associated with a better outcome. From ‘during‐treatment factors’ a higher CBT ‘proficiency score’ ([a] acceptance of the explanation that SGB is a behavioural phenomenon [b] detection of a warning signal before belching [c] adherence to the exercises treatment) was associated with a better outcome (P = .001). Multiple regression analysis found that number of SGBs, hypervigilance score and CBT proficiency score were independently associated with outcome (P < .01, P = .01, P < .01). VAS score before CBT (267 ± 79) decreased to 151 ± 88 soon after CBT (P < .001), and the effect persisted at 6‐12 months follow‐up (153 ± 82).Conclusions: Lower number of SGBs, lower hypervigilance score and higher proficiency during CBT were associated with better CBT outcome. CBT positive effect lasted for at least 6‐12 months post‐treatment.

Akinari Sawada, Daniel Sifrim, and Yasuhiro Fujiwara. Gut and Liver 2023;17:831-42. https://doi.org/10.5009/gnl220373

Eosinophilic esophagitis (EoE) has been increasingly diagnosed globally. However, there have been few general population-based studies in Asia. The aim of this study was to investigate EoE epidemiology in the Japanese general population. We analyzed an employer-based health insurance claim database from January 2005 to September 2022. EoE cases were identified on the basis of the International Statistical Classification of Diseases and Health-related Problems, 10th Revision code, K20.0. We calculated the incidence and prevalence of EoE using Poisson regression and binomial distribution, respectively. Using 10 matched controls for each EoE case, a nested case-control study was performed to identify potential risk factors for EoE. Of 15,200,895 individuals, 1010 EoE cases were identified. The incidence and prevalence of EoE were 2.82 (95% confidence interval [CI], 2.44-3.26) per 100,000 person-years and 10.68 (95% CI, 10.01-11.37) per 100,000 people in 2022, nearly 3 and 8 times as high as those in 2017, respectively. Smoking was associated with decreased risk of EoE (odds ratio [OR], 0.45, 0.36-0.56, P < .001), whereas alcohol consumption (OR, 1.51, 1.21-1.88, P < .001) was associated with increased risk of EoE along with several allergic conditions and psychiatric disorders. EoE was not related to either body mass index or lifestyle-related diseases such as hypertension, diabetes mellitus, hyperuricemia, and dyslipidemia. The incidence and prevalence of EoE in Japan have steadily increased over the past 2 decades. Nevertheless, EoE remains less common in Japan compared with the United States and Western Europe. Factors contributing to the epidemiology of EoE on a global basis may improve our understanding of the contribution of genetic and environmental risk factors.