Superficial Esophageal Mucosal Afferent Nerves May Contribute to Reflux Hypersensitivity in Nonerosive Reflux Disease

Recent advances in the knowledge of the mechanism of reflux hypersensitivity

Reflux hypersensitivity (RH) is a subtype of gastroesophageal reflux disease. The Rome IV criteria separated RH from the original nonerosive reflux disease subgroup and classified it as a new functional oesophageal disease. Recently, the pathogenesis of RH has become the focus of research. According to the latest research reports, upregulation of acid-sensitive receptors, distribution of calcitonin gene-related peptide-positive nerve fibres, and psychiatric comorbidity have key roles in the pathogenesis of RH. This work reviews the latest findings regarding RH mechanisms.

Mucosal neuroimmune mechanisms in gastro-oesophageal reflux disease (GORD) pathogenesis

Gastro-oesophageal reflux disease (GORD) is a chronic condition characterised by visceral pain in the distal oesophagus. The current first-line treatment for GORD is proton pump inhibitors (PPIs), however, PPIs are ineffective in a large cohort of patients and long-term use may have adverse effects. Emerging evidence suggests that nerve fibre number and location are likely to play interrelated roles in nociception in the oesophagus of GORD patients. Simultaneously, alterations in cells of the oesophageal mucosa, namely epithelial cells, mast cells, dendritic cells, and T lymphocytes, have been a focus of GORD research for several years. The oesophagus of GORD patients exhibits both macro- and micro-inflammation as a response to chronic acidic reflux at the epithelium. In other conditions of the GI tract, such as IBS and IBD, well-characterised bidirectional processes between immune cells and mucosal nerve fibres contribute to pathogenesis and symptom generation. Sensory alterations in these conditions such as nerve fibre outgrowth and hypersensitivity can be driven by inflammatory processes, which promote visceral pain signalling. This review will examine what is currently known of the molecular pathways linking inflammation and sensory perception leading to the development of GORD symptoms and explore potentially relevant mechanisms in other GI regions which may indicate new areas in GORD research.

Superficial oesophageal mucosal innervation may contribute to severity of symptoms in oesophageal motility disorders

BACKGROUND

Mechanisms underlying perception of dysphagia and chest pain have not been completely elucidated, although oesophageal mucosal afferent nerves might play an important role.

AIMS

To evaluate the relationship between oesophageal mucosal afferent nerves and the severity of dysphagia and chest pain in oesophageal motility disorders.

METHODS

We prospectively recruited patients with oesophageal motility disorders having dysphagia and/or chest pain from whom oesophageal biopsies were obtained. High-resolution manometry classified patients into disorders of oesophagogastric junction (OGJ) outflow and disorders of peristalsis. Symptom severity was assessed using validated questionnaires including Brief Oesophageal Dysphagia Questionnaire (BEDQ). Immunohistochemistry was performed on oesophageal biopsies to evaluate the location of calcitonin gene-related peptide (CGRP)-immunoreactive mucosal afferent nerves. Findings were compared to existing data from 10 asymptomatic healthy volunteers.

RESULTS

Of 79 patients, 61 patients had disorders of OGJ outflow and 18 had disorders of peristalsis. CGRP-immunoreactive mucosal nerves were more superficially located in the mucosa of patients with oesophageal motility disorders compared to healthy volunteers. Within disorders of OGJ outflow, the location of CGRP-immunoreactive nerves negatively correlated with BEDQ score both in the proximal (ρ = -0.567, p < 0.001) and distal oesophagus (ρ = -0.396, p = 0.003). In the proximal oesophagus, strong chest pain was associated with more superficially located mucosal nerves than weak chest pain (p = 0.04). Multivariate analysis showed superficial nerves in the proximal oesophagus was independently associated with severe dysphagia in disorders of OGJ outflow (p = 0.008).

CONCLUSIONS

Superficial location of mucosal nerves in the proximal oesophagus might contribute to symptoms, especially severe dysphagia, in disorders of OGJ outflow.

Editorial: Is there a relationship between dysphagia, chest pain and mucosal innervation in patients with oesophageal motility disorders?

This article is linked to Sawada et al paper. To view this article, visit https://doi.org/10.1111/apt.17773

Esophageal Reflux Hypersensitivity: A Comprehensive Review

Reflux hypersensitivity (RH) is one of the phenotypes of gastroesophageal reflux disease. The latest Rome IV defines RH as a condition with typical reflux symptoms and positive reflux-symptom association despite normal acid exposure. Subsequently, the Lyon consensus proposed detailed cutoff values for the criteria on the basis of experts' consensus. Rome IV brought a clear-cut perspective into the pathophysiology of gastroesophageal reflux disease and the importance of esophageal hypersensitivity. This perspective can be supported by the fact that other functional gastrointestinal disorders such as irritable bowel syndrome and functional dyspepsia often overlap with RH. Although several possible pathophysiological mechanisms of esophageal hypersensitivity have been identified, there is still unmet medical needs in terms of treatment for this condition. This review summarizes the current knowledge regarding RH.

A perspective on the clinical relevance of weak or nonacid reflux

BACKGROUND

Advances in ambulatory esophageal reflux monitoring that incorporated impedance electrodes to pH catheters have resulted in better characterization of retrograde bolus flow in the esophagus. With pH-impedance monitoring, in addition to acid reflux episodes identified by pH drops below 4.0, weakly acid reflux (WAR, pH 4-7) and nonacid reflux (NAR, pH >7.0) are also recognized, although both may be included under the umbrella term NAR. However, despite identification of ambulatory pH-impedance monitoring, data on clinical relevance and prognostic value of NAR are limited. The Lyon Consensus, an international expert review that defines conclusive metrics for gastroesophageal reflux disease (GERD), identifies NAR as "supportive" but not conclusive for GERD.

PURPOSE

This review provides perspectives on whether NAR fulfills three criteria for clinical relevance: whether NAR sufficiently explains pathogenesis of symptoms, whether it is associated with meaningful manifestations of GERD, and whether it can predict treatment efficacy.

Revisiting the Role of Esophageal Mucosal Dilated Intercellular Spaces in the Diagnosis and Pathophysiology of Heartburn

Background/Aims

Dilated intercellular spaces (DISs) facilitate the diffusion of noxious agents into the deep layers of the esophageal epithelium. The role of DIS in heartburn pathogenesis is still controversial. Therefore, we aim to reinvestigate DIS in an extensively evaluated group of patients and healthy controls (HCs).

Methods

We classified 149 subjects into the following groups: 15 HC, 58 mild erosive reflux disease (ERD), 17 severe ERD, 25 nonerosive reflux disease (NERD), 15 reflux hypersensitivity (RH), and 19 functional heartburn (FH). A total of 100 length measurements were performed for each patient's biopsy.

Results

The overall intercellular spaces (ISs) value of gastroesophageal reflux disease (GERD) patients was higher than that of HC (P = 0.020). In phenotypes, mild ERD (vs HC [P = 0.036], NERD [P = 0.004], RH [P = 0.014]) and severe ERD (vs HC [P = 0.002], NERD [P < 0.001], RH [P = 0.001], FH [P = 0.004]) showed significantly higher IS. There was no significant difference between the HC, NERD, RH, and FH groups. The 1.12 μm DIS cutoff value had 63.5% sensitivity and 66.7% specificity in the diagnosis of GERD. There was a weak correlation (r = 0.302) between the IS value and acid exposure time, and a weak correlation (r = -0.359) between the IS value and baseline impedance. A strong correlation was shown between acid exposure time and baseline impedance (r = -0.783).

Conclusions

Since the IS length measurement had better discrimination power only in erosive groups, it is not feasible to use in daily routine to discriminate other nonerosive phenotypes and FH. The role of DIS in heartburn in nonerosive patients should be reconsidered.

Esophageal secondary peristalsis following acid infusion and chemical clearance correlate with mucosal integrity and acid sensitivity in GERD patients

Background

Acid sensitivity can be altered in patients with gastroesophageal reflux disease (GERD). Secondary peristalsis helps clear gastro-esophageal refluxate and residual ingested food bolus.

Objectives

The aim of this study was to investigate the associations among acid sensitivity, esophageal mucosal integrity, chemical clearance, and secondary peristalsis before and after esophageal acid infusion.

Design

This was an investigator-initiated, prospective, cross-sectional study.

Methods

Adult reflux patients underwent high resolution manometry and 24 h impedance-pH monitoring off acid suppression to identify GERD phenotypes, including non-erosive reflux disease (NERD), reflux hypersensitivity (RH), and functional heartburn (FH). Secondary peristalsis was assessed using five rapid 20 mL air injections into the esophagus before and after infusion of hydrochloric acid (0.1 N) into the mid-esophagus. Conventional acid infusion parameters recorded included lag time, intensity rating, and sensitivity score. Chemical clearance was evaluated using the post-reflux swallow-induced peristaltic wave (PSPW), and mucosal integrity was assessed by the mean nocturnal baseline impedance (MNBI) derived from impedance-pH monitoring.

Results

A total of 88 patients (age 21-64 years, 62.5% women) completed the study including 12 patients with NERD, 45 with RH, and 31 with FH. There was no significant difference in acid infusion parameters between patients with NERD, RH, and FH. Upon acid infusion, patients who exhibited successful secondary peristalsis had longer lag time, higher MNBI, and shorter bolus contact time than those without secondary peristalsis. Meanwhile, patients with intact PSPW demonstrated significantly higher intensity ratings in response to acid perfusion and higher MNBI than those with impaired PSPW. The lag time correlated positively with MNBI (r = 0.285; p = 0.007).

Conclusion

In conclusion, the protective effect of esophageal secondary peristalsis and chemical clearance on esophageal mucosal integrity was demonstrated. Concerning acid sensitivity, longer lag time in patients with intact secondary peristalsis may be attributed to better esophageal mucosal integrity, while stronger intensity ratings may have a greater tendency to induce PSPW and protect esophageal mucosal integrity.

Sensory Phenotype of the Oesophageal Mucosa in Gastro-Oesophageal Reflux Disease

Gastroesophageal reflux disease (GORD) affects up to 20% of Western populations, yet sensory mechanisms underlying heartburn pathogenesis remain incompletely understood. While central mechanisms of heartburn perception have been established in earlier studies, recent studies have highlighted an important role of neurochemical, inflammatory, and cellular changes occurring in the oesophageal mucosa itself. The localization and neurochemical characterisation of sensory afferent nerve endings differ among GORD phenotypes, and could explain symptom heterogeneity among patients who are exposed to similar levels of reflux. Acid-induced stimulation of nociceptors on pain-sensing nerve endings can regulate afferent signal transmission. This review considers the role of peripheral mechanisms of sensitization in the amplification of oesophageal sensitivity in patients with GORD.

The Potential Role for Impaired Mucosal Integrity in the Generation of Esophageal Pain Using Capsaicin in Humans: An Explorative Study

INTRODUCTION

Esophageal pain is mediated by sensory nerves, most importantly by the activation of the transient receptor potential vanilloid 1 (TRPV1) capsaicin receptor. TRPV1 is activated and sensitized by a broad range of pungent compounds, as well as inflammatory mediators and tissue irritants. Luminal stressors are suggested to impair the barrier function, which results in consequent activation of these sensory nerve terminals and pain. In this study, we investigated the effect of the perfusion of capsaicin, a TRPV1 agonist, on mucosal impedance and pain in asymptomatic volunteers.

METHODS

Thirteen asymptomatic volunteers completed a single-blind, saline-controlled, randomized crossover study. Capsaicin or saline was perfused for 30 minutes in the distal esophagus. Visual analog scale pain intensity scores and intraluminal impedance indicating mucosal integrity were determined. Distal and proximal biopsies were obtained 10 minutes later to measure TRPV1 messenger RNA and TRPV1 immunopositivity, as well as the intercellular space area.

RESULTS

Capsaicin perfusion resulted in significantly greater pain intensity (P = 0.047) and impaired recovery of the mucosal impedance compared with saline-treated controls (P = 0.027). Pain response was significantly associated with decreased mucosal impedance. Similar dynamics were seen in the proximal esophagus, but mucosal impedance recovered entirely to the preinfusion values there. There was a significant association between mucosal impedance and intercellular space width in the distal esophagus. TRPV1 transcription and expression were not significantly altered within this observation period.

DISCUSSION

Esophageal capsaicin perfusion results in pain, which is likely to be explained by impaired mucosal impedance and defective restoration capacity in the distal esophagus.

CORRELATION BETWEEN SYMPTOMS AND REFLUX IN PATIENTS WITH GASTROESOPHAGEAL REFLUX DISEASE

BACKGROUND

Esophageal symptoms of gastroesophageal reflux are the same in functional heartburn, non-erosive disease, and erosive disease. Their patient-perceived intensity may be related to gastroesophageal reflux intensity.

OBJECTIVE

To evaluate whether the symptoms in GERD patients are related to the intensity of gastroesophageal acid reflux.

METHODS

To test this hypothesis, 68 patients with heartburn (18 with functional heartburn, 28 with non-erosive reflux disease, and 22 with erosive reflux disease) had their symptoms evaluated by the Velanovich score (which mainly focuses on heartburn) and the Eating Assessment Tool (EAT-10) (which focuses on dysphagia). They were submitted to esophageal endoscopy and then, on another day, they answered the Velanovich and EAT-10 questionnaires and underwent manometry and 24-hour pHmetry (measured 5 cm proximal to the upper border of the lower esophageal sphincter).

RESULTS

The Velanovich score was higher in patients with non-erosive and erosive diseases than in those with functional heartburn. The mean EAT-10 score did not differ between functional heartburn, erosive, and non-erosive gastroesophageal reflux disease. Considering the threshold of ≥5 to define dysphagia, 4 (22%) patients with functional heartburn, 12 (43%) with non-erosive disease, and 9 (41%) with erosive disease had dysphagia (P=0.18). There was: a) a moderate correlation between the Velanovich and DeMeester score and between Velanovich score and the percentage of acid exposure time (AET); b) a weak correlation between EAT-10 and DeMeester score and between EAT-10 and acid exposure time.

CONCLUSION

There is a moderate positive correlation between heartburn and gastroesophageal reflux measurement. Dysphagia has a weak positive correlation with reflux measurement.

Rapid response to galcanezumab and predictive factors in chronic migraine patients: A 3-month observational, longitudinal, cohort, multicenter, Italian real-life study

BACKGROUND AND PURPOSE

A rapid response to preventive therapy is of pivotal importance in severely disabled patients with chronic migraine (CM) and diverse preventive treatment failures. This prospective, observational, multicenter real-life study aimed at investigating the effectiveness of galcanezumab in the first 3 months of treatment of CM patients at 14 Italian headache centers.

METHODS

All consecutive adult patients with CM diagnosis with the clinical indication for galcanezumab were considered. We collected patients' baseline characteristics, monthly headache days, monthly painkiller intake, migraine clinical characteristics, and disability scale scores during a 1-month run-in period (baseline) and the first 3 months of therapy. Possible predictive factors of treatment were considered.

RESULTS

A total of 156 patients (82.4% female, aged 47.3 ± 12.3 years) were enrolled. The 65 (41.7%) patients with a consecutive ≥50% response rate (RR) in the 3 months of therapy presented a lower body mass index (p = 0.004) and more frequently presented unilateral migraine pain (p = 0.002) and good response to triptans (p = 0.003). Persistent conversion from CM to episodic migraine was observed in 55.8% (87/156) of patients. They more frequently presented a good response to triptans (p = 0.003) and unilateral pain (p = 0.046). At baseline, 131 of 156 (83.9%) patients presented medication overuse (MO). Of these, 61.8% (81/131) no longer displayed MO consistently during the 3 months. These patients were more frequently responders to triptans (p = 0.002) and less frequently suffered from gastrointestinal comorbidity (p = 0.007).

CONCLUSIONS

Unilateral pain, good response to triptans, and normal weight may be associated with a persistent positive response in the first 3 months of therapy with galcanezumab in CM patients.

Efficacy of Endoscopic Radiofrequency Ablation for Treatment of Reflux Hypersensitivity: A Study Based on Rome IV Criteria

Objective. Effective therapies for reflux hypersensitivity are lacking. Endoscopic radiofrequency ablation may reduce the sensitivity of the distal esophagus through direct interference with nociceptors or vagal afferent fibers and thus may be useful in reflux hypersensitivity. The aim of this study is to assess the effectiveness and possible mechanisms of endoscopic radiofrequency ablation in reflux hypersensitivity patients. Methods. Patients with reflux hypersensitivity who fulfilled the Rome IV criteria and who wished to receive further treatment were recruited. Endoscopic radiofrequency ablation was delivered to the gastroesophageal junction. Data were collected by questionnaire using a 6-point Likert scale. The primary outcome measure was effect on symptoms including heartburn, regurgitation, and chest pain. The secondary outcomes were degree of satisfaction, medication use, acid exposure time (AET), low esophageal sphincter (LES) pressure, and total reflux episodes. We also assessed positive cell density of transient receptor potential vanilloid type 1 receptor (TRPV1) and calcitonin gene-related peptide (CGRP), both of which are biomarkers of afferent fibers, in biopsies obtained from esophageal mucosa 0.5 cm-1 cm above the Z line. These scales will be administered at baseline, 3-month follow-up, 6-month follow-up, and 12-month follow-up. Results. A total of 22 reflux hypersensitivity patients were enrolled (14 males, median age 50.0 years). A significant improvement in symptom scores (heartburn, regurgitation, and chest pain) was noted at 3 months, 6 months, and 12 months ( $P<0.001$ ). Satisfaction with life increased to 72.7% (16/22), 72.7% (16/22), and 68.2% (15/22) at 3, 6, and 12 mo, respectively, compared with baseline ( $P<0.001$ ). Nineteen patients reduced their medication use after treatment. Of these, 22.7% (5/22), 31.8% (7/22), and 40.9% (9/22) subjects stopped medication use at 3 mo, 6 mo, and 12 mo, respectively. No statistical differences were noted in AET, LES pressure, or total reflux episodes from preoperation to 12 mo postoperation. After treatment, the positive cell density of both TRPV1 and CGRP decreased significantly; however, only TRPV1 had a positive correlation with heartburn ( $r=0.51$ , $P=0.03$ ) and chest pain ( $r=0.77$ , $P<0.01$ ). Conclusion. Endoscopic radiofrequency ablation was an effective and safe therapeutic option in reflux hypersensitivity patients. Further studies with large sample size are required to validate the role of radiofrequency in reflux hypersensitivity.

Pathophysiology of Pediatric Gastroesophageal Reflux Disease: Similarities and Differences With Adults

Gastroesophageal reflux (GOR) is defined as "the passage of gastric contents into the esophagus with or without regurgitation and vomiting" and gastroesophageal reflux disease (GORD) is defined "when GOR leads to troublesome symptoms affecting the daily functioning and/or complications." This definition was first developed in 2006 by the Montreal consensus group (1) and later on adopted by pediatric gastroenterology societies such as ESPGHAN and NASPGHAN in 2009 (2). The definition of gastroesophageal reflux reveals little about its pathophysiology and is focused on symptomatology. In this way, it acts as an umbrella term for the multifactorial causes of the disease and the various phenotypes encountered; from functional heartburn to hypersensitive esophagus and nonerosive reflux disease, to erosive esophagitis and Barrett's esophagus. This article is devoted to the pathophysiology of pediatric GORD in comparison to adult GORD and is divided in 2 parts. In the first part, we will systematically describe the different mechanisms for the generation and clearance of reflux events, while on the second part we will discuss the mechanisms involved in symptoms generation. Finally, we will discuss the similarities and differences between pediatric and adult GORD.

Esophageal mucosal sensory nerves and potential mechanoreceptors in patients with ineffective esophageal motility

BACKGROUND

Ineffective esophageal motility (IEM) is the most common motility disorder. However, little is known about its pathophysiology. Vagal afferent nerves convey esophageal intraluminal bolus information to solitary nucleus, which is likely to be involved with esophageal primary and secondary peristalsis (SP). We hypothesized that altered mucosal sensory afferents underlie the pathogenesis of IEM.

METHODS

We prospectively collected esophageal biopsies from 38 patients with proton pump inhibitor-refractory reflux symptoms from January to December 2019. All patients underwent high-resolution manometry for the evaluation of primary and secondary peristalsis, and off-PPI 24-h impedance-pH studies. Biopsies were analyzed using immunohistochemistry for identification of calcitonin gene-related peptide-immunoreactive (CGRP-IR) nerves and qPCR for mRNA expression of potential mechanoreceptors.

KEY RESULTS

Overall 32 patients were finally analyzed which consisted of 11 patients with normal motility and 21 patients with IEM. The position of mucosal CGRP-IR nerves from the esophageal lumen did not differ between the two groups (the proximal esophagus (p = 0.52), the mid-esophagus (p = 0.92), the distal esophagus (p = 0.29)) with the similar reflux profile. No difference was seen in the position of CGRP-IR nerves between patients with successful triggering of SP and those unable to trigger SP. There was also no difference in mRNA expression of each potential mechanoreceptors (TRPA1, TRPV1, TRPV4, ASIC1, ASIC3) between the two groups.

CONCLUSIONS AND INFERENCES

Our study showed that mucosal sensory afferents nerve position and mRNA expression of potential mechanoreceptors did not correlate to weak esophageal contraction.

Functional Chest Pain and Esophageal Hypersensitivity: A Clinical Approach

Functional chest pain, functional heartburn, and reflux hypersensitivity are 3 functional esophageal disorders defined by the Rome IV criteria. Specific criteria, combining symptoms and the results of objective testing, allow for an accurate diagnosis of these conditions. Management may include medications targeted at optimizing acid suppression or neuromodulation, as well as a host of complementary or alternative treatment options. Psychological and behavioral interventions, such as cognitive behavioral therapy and hypnotherapy, have displayed substantial benefits in the treatment of functional chest pain and functional heartburn. Acid suppression and focused neuromodulation are key evidence-based treatment options for reflux hypersensitivity.

Impaired Mucosal Integrity in Proximal Esophagus Is Involved in Development of Proton Pump Inhibitor-Refractory Nonerosive Reflux Disease

BACKGROUND AND OBJECTIVE

Weakly acidic reflux reaching to the proximal esophagus is closely related to the perception of gastroesophageal reflux in patients with nonerosive reflux disease despite treatment with a proton pump inhibitor (PPI). However, little is known about the involvement of the patients' mucosal integrity of the proximal esophagus.

METHODS

We recruited 15 symptomatic nonerosive gastroesophageal reflux disease (GERD) patients with a positive symptom index despite PPI treatment and 11 healthy asymptomatic volunteers as controls. The biopsy specimens obtained from the proximal and distal esophagus were applied to a mini-Ussing chamber system to measure transepithelial electrical resistance (TEER) against a pH 4 weak acid. The esophageal biopsy samples were subjected to quantitative real-time PCR and immunohistochemical analysis.

RESULTS

In the proximal esophagus, the weak acid exposure reduced the TEER in the PPI-refractory patients compared to that in the controls. The frequency of the reflux extending to the proximal esophagus had a significant correlation with the reduction in the proximal esophageal TEER in the patients. The reduced TEER in the proximal esophagus was accompanied by an increase in IL-8 and IL-1β mRNA and a decrease in occludin mRNA levels. The proximal esophageal mucosa in the patients presented infiltration of CD3-positive lymphocytes and an increased expression of solute carrier organic anion transporter family member 2A1 (SLCO2A1), a passage gate of reflux symptom-evoking molecules.

CONCLUSIONS

The reflux perception is related to an impairment of the proximal esophageal mucosal integrity in patients with nonerosive reflux disease despite PPI.

Esophageal Mucosa Innervation in Children With Nonerosive Reflux Disease

INTRODUCTION

Esophageal mucosa innervation in adults with nonerosive reflux disease (NERD) is more superficial compared with healthy volunteers. We delineated the esophageal mucosal innervation in pediatric NERD and controls.

METHODS

Distal and proximal pediatric esophageal biopsies were immunohistochemically stained with calcitonin gene-related peptide and transient receptor potential cation channel subfamily V member 1.

RESULTS

Mucosal innervation was assessed in 18 controls (9M:9F, median age: 9 years) and 11 NERD patients (6M:5F, median age: 5 years). Calcitonin gene-related peptide positive nerve fibers were lying deep in the mucosa in both groups, P > 0.05 and did not coexpress transient receptor potential cation channel subfamily V member 1.

DISCUSSION

The pediatric esophageal mucosa in NERD displays deep lying nerve fibers, in contrast to adults.

Gastro-oesophageal reflux disease

Gastro-oesophageal reflux disease (GERD) is a common disorder in adults and children. The global prevalence of GERD is high and increasing. Non-erosive reflux disease is the most common phenotype of GERD. Heartburn and regurgitation are considered classic symptoms but GERD may present with various atypical and extra-oesophageal manifestations. The pathophysiology of GERD is multifactorial and different mechanisms may result in GERD symptoms, including gastric composition and motility, anti-reflux barrier, refluxate characteristics, clearance mechanisms, mucosal integrity and symptom perception. In clinical practice, the diagnosis of GERD is commonly established on the basis of response to anti-reflux treatment; however, a more accurate diagnosis requires testing that includes upper gastrointestinal tract endoscopy and reflux monitoring. New techniques and new reflux testing parameters help to better phenotype the condition. In children, the diagnosis of GERD is primarily based on history and physical examination and treatment vary with age. Treatment in adults includes a combination of lifestyle modifications with pharmacological, endoscopic or surgical intervention. In refractory GERD, optimization of proton-pump inhibitor treatment should be attempted before a series of diagnostic tests to assess the patient's phenotype.

Esophageal afferent innervation and its role in gastro-esophageal reflux disease symptoms

PURPOSE OF REVIEW

Despite the wide prevalence of gastro-esophageal reflux disease (GERD), the neurophysiological mechanisms underlying heartburn perception in the esophagus of patients with GERD remains incompletely understood. Recent studies have highlighted the potential influence sensory afferent nerves innervating the oesophageal epithelium may have on heartburn pathogenesis. The purpose of this review is to consider the current understanding of esophageal afferent neuronal innervation, including the nociceptive role of acid-sensing receptors expressed on these sensory nerves, in relation to pain perception in the esophagus of GERD patients.

RECENT FINDINGS

Central and peripheral pathways of sensitization following noxious stimulation of nociceptive receptors expressed on afferent nerves can regulate the strength of sensory nerve activation in the esophagus, which can result in the amplification or suppression of afferent signal transmission. The localization and characterization of mucosal sensory afferent nerves vary between GERD phenotypes and may explain the heterogeneity of symptom perception in patients with apparently similar levels of reflux.

SUMMARY

In this review, we discuss the relevance of afferent esophageal innervation in heartburn perception, with a particular focus on the pathways of reflux-induced activation of nociceptive nerves.

Heartburn sensation in nonerosive reflux disease: pattern of superficial sensory nerves expressing TRPV1 and epithelial cells expressing ASIC3 receptors

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.

Pharmacological Management of Gastro-Esophageal Reflux Disease: An Update of the State-of-the-Art

Gastro-esophageal reflux disease (GERD) is a highly prevalent, chronic disorder, whose knowledge remains limited and the management of these patients changes continuously. This review provides a summary of the most recent advancements in the pathogenesis of this disease and the new drugs introduced into the market to overcome some of the unmet needs of traditional therapies. Nowadays, the most fruitful diagnostic examinations are 24-hour impedance-pH monitoring, which allows us to separate true NERD from esophageal functional disorders and high-resolution manometry, which helps to exclude the existence of motility disorders sharing the same symptoms of GERD. Proton pump inhibitors (PPIs) remain the first-choice therapy in the treatment of GERD, but a consistent proportion of these patients continue to experience symptoms despite their intake. These cases pertain mainly to the subpopulation with non-erosive reflux disease (NERD) and represent very challenging clinical situations, because it is mandatory to understand the reasons for PPI failure. The management of these difficult patients requires necessarily to test them and avoid the use of empiric treatments that are often unsuccessful, costly and potentially dangerous. Recently, several new drugs have been used to increase the defensive properties of this mucosa with promising results in randomized clinical trials.

Erosive Esophagitis and Symptoms of Gastroesophageal Reflux Disease in Patients with Morbid Obesity with and without Type 2 Diabetes: a Cross-sectional Study

BACKGROUND

Type 2 diabetes (T2DM) is associated with gastroesophageal reflux disease (GERD) in the general population, but the relationship between these conditions in candidates for bariatric surgery is uncertain. We compared the prevalence of GERD and the association between GERD symptoms and esophagitis among bariatric candidates with and without T2DM.

METHODS

Cross-sectional study of baseline data from the Oseberg study in Norway. Both groups underwent gastroduodenoscopy and completed validated questionnaires: Gastrointestinal Symptom Rating Scale and Gastroesophageal Reflux Disease Questionnaire. Participants with T2DM underwent 24-h pH-metry.

RESULTS

A total of 124 patients with T2DM, 81 women, mean (SD) age 48.6 (9.4) years and BMI 42.3 (5.5) kg/m², and 64 patients without T2DM, 46 women, age 43.0 (11.0) years and BMI 43.0 (5.0) kg/m², were included. The proportions of patients reporting GERD-symptoms were low (< 29%) and did not differ significantly between groups, while the proportions of patients with esophagitis were high both in the T2DM and non-T2DM group, 58% versus 47%, p = 0.16. The majority of patients with esophagitis did not have GERD-symptoms (68-80%). Further, 55% of the patients with T2DM had pathologic acid reflux. Among these, 71% also had erosive esophagitis, whereof 67% were asymptomatic.

CONCLUSIONS

The prevalence of GERD was similar in bariatric patients with or without T2DM, and the proportion of patients with asymptomatic GERD was high independent of the presence or absence of T2DM. Accordingly, GERD may be underdiagnosed in patients not undergoing a preoperative endoscopy or acid reflux assessment.

TRIAL REGISTRATION

Clinical Trials.gov number NCT01778738.

ESNM/ANMS consensus paper: Diagnosis and management of refractory gastro-esophageal reflux disease

Up to 40% of patients with symptoms suspicious of gastroesophageal reflux disease (GERD) do not respond completely to proton pump inhibitor (PPI) therapy. The term "refractory GERD" has been used loosely in the literature. A distinction should be made between refractory symptoms (ie, symptoms may or may not be GERD-related), refractory GERD symptoms (ie, persisting symptoms in patients with proven GERD, regardless of relationship to ongoing reflux), and refractory GERD (ie, objective evidence of GERD despite adequate medical management). The present ESNM/ANMS consensus paper proposes use the term "refractory GERD symptoms" only in patients with persisting symptoms and previously proven GERD by either endoscopy or esophageal pH monitoring. Even in this context, symptoms may or may not be reflux related. Objective evaluation, including endoscopy and esophageal physiologic testing, is requisite to provide insights into mechanisms of symptom generation and evidence of true refractory GERD. Some patients may have true ongoing refractory acid or weakly acidic reflux despite PPIs, while others have no evidence of ongoing reflux, and yet others have functional esophageal disorders (overlapping with proven GERD confirmed off therapy). In this context, attention should also be paid to supragastric belching and rumination syndrome, which may be important contributors to refractory symptoms.

Association of residual gastric acid secretion with persistent symptoms in gastroesophageal reflux disease patients receiving standard-dose proton pump inhibitor therapy

BACKGROUND

Although a third of gastroesophageal reflux disease (GERD) patients are refractory to proton pump inhibitor (PPI) therapy, the underlying mechanism of the refractoriness remains unclear. We compared the level of gastric acid suppression during PPI treatment between responders and non-responders by directly measuring gastric acid secretion in GERD patients taking PPIs.

METHODS

Seventy-five consecutive patients receiving standard-dose PPI therapy for GERD were prospectively recruited, irrespective of persistent GERD symptoms. They were asked about their GERD symptoms using a validated questionnaire, and simultaneously underwent both a routine endoscopic examination and a gastric acid secretory testing using an endoscopic gastrin test. Associations between residual gastric acid secretion during PPI treatment and persistent GERD symptoms were analyzed by a logistic regression analysis.

RESULTS

Overall, 26 of 75 (34.7%) patients were judged to be positive for persistent GERD symptoms. The patients with and without persistent symptoms showed similar gastric acid secretion levels (1.3 [1.3] mEq/10 min vs. 1.4 [2.0] mEq/10 min). Sufficient gastric acid suppression, defined as < 0.6, was not significantly associated with persistent GERD symptoms (odds ratio 1.1, 95% confidence interval 0.40-3.5).

CONCLUSIONS

This study provided solid evidence to support that the gastric acid suppression level during PPI treatment does not differ between patients with and without persistent GERD symptoms. The insignificant role of residual gastric acid in the persistent GERD symptoms suggests that the use of medications other than those that enhance gastric acid inhibitory effects would be an essential approach for the management of PPI-refractory GERD.

Mucosal pathogenesis in gastro-esophageal reflux disease

BACKGROUND

Despite gastro-esophageal reflux disease affecting up to 20% of Western populations, relatively little is known about the molecular mechanisms underlying its most troublesome symptom: heartburn. Recent findings have unveiled the role of components of the esophageal mucosa in the pathogenesis of GERD including sensory nociceptive nerves and inflammatory mediators. Erosive esophagitis was long believed to develop as a result of acid injury at the esophageal lumen, but novel concepts suggest the generation of reflux-induced esophageal injury as a result of cytokine-mediated inflammation. Moreover, the localization and characterization of mucosal afferent nerves vary between GERD phenotypes and could explain the heterogeneity of symptom perception between patients who experience similar levels of acid reflux.

PURPOSE

The purpose of this review is to consider the crosstalk of different factors of the esophageal mucosa in the pathogenesis of GERD, with a particular focus on mucosal innervation and molecular basis of acid-induced cytokine response. We discuss the current understanding of the mucosal response to acid injury, the nociceptive role of acid-sensitive receptors expressed in the esophageal mucosa, and the role of esophageal epithelial cells in initiating the onset of erosive esophagitis.

A SIGE-SINGEM-AIGO technical review on the clinical use of esophageal reflux monitoring

Patients with esophageal symptoms potentially associated with gastroesophageal reflux disease such as heartburn, regurgitation, chest pain, or cough represent one of the most frequent reasons for referral to gastroenterological evaluation. The utility of esophageal reflux monitoring in clinical practice is: (1) to accurately define reflux burden, (2) to segregate patients according to reflux monitoring results as true GERD, reflux hypersensitivity and functional heartburn, and (3) to establish a treatment plan. With this in mind, in the last decade, investigations and technical advances, with the introduction of impedance-pH monitoring and wireless pH capsule, have enhanced our understanding and management of GERD. The following recommendations were discussed and approved after a comprehensive review of the medical literature pertaining to reflux testing techniques and their recent application. This review created under the auspices of the Società Italiana di Gastroenterologia ed Endoscopia Digestiva (SIGE), Società Italiana di Neuro-Gastro-Enterologia e Motilità (SINGEM) and Associazione Italiana Gastroenterologi ed Endoscopisti Digestivi Ospedalieri (AIGO) is intended to help clinicians in applying reflux studies in the most fruitful manner within the context of their patients with esophageal symptoms.

Duration of adhesion of swallowed alginates to distal oesophageal mucosa: implications for topical therapy of oesophageal diseases

BACKGROUND

We have previously shown, ex vivo, that alginate solutions can have a topical protective effect on oesophageal mucosal biopsies exposed to simulated gastric juice. Oesophageal mucosal impedance can measure the duration of mucosal adherence of ionic solutions since the impedance drops when the solution is present, and rises to baseline as the solution clears.

AIM

To investigate the in vivo duration of adhesion of swallowed alginate solution to distal oesophageal mucosa.

METHODS

We studied 20 healthy volunteers and 10 patients with heartburn. A pH-impedance catheter was inserted, and baseline distal channel oesophageal impedance measured. Healthy volunteers received 10 mL of either sodium alginate (Gaviscon Advance), Gaviscon placebo (no alginate) or viscous slurry (saline mixed with sucralose), given in a randomised, single-blinded order over three visits. Patients received either sodium alginate or placebo on two visits. Initial impedance drop was measured, then 1-minute mean impedance was measured each minute until ≥75% recovery to baseline.

RESULTS

In healthy volunteers, sodium alginate adhered to the oesophageal mucosa for longer than placebo or viscous slurry (10.4 [8.7] minutes vs 1.1 [1.6] vs 3.6 [4.0], P < 0.01). In patients, sodium alginate adhered to the oesophageal mucosa for longer than placebo (9.0 (5.4) vs 3.7 (4.1), P < 0.01).

CONCLUSIONS

Sodium alginate solution adhered to the oesophageal mucosa for significantly longer than placebo or viscous slurry. This demonstrates that alginates could confer a protective benefit due to mucoadhesion and can be a basis for further development of topical protectants and for topical drug delivery in oesophageal disease.

Non-acid Reflux: When It Matters and Approach to Management

PURPOSE OF REVIEW

This narrative review focuses on the presentation, contributing factors, diagnosis, and treatment of non-acid reflux. We also propose algorithms for diagnosis and treatment.

RECENT FINDINGS

There is a paucity of recent data regarding non-acid reflux. The recent Porto and Lyon consensus statements do not fully address non-acid reflux or give guidance on classification. However, recent developments in the lung transplantation field, as well as older data in the general population, argue for the importance of non-acid reflux. Extrapolating from the Porto and Lyon consensus, we generally classify pathologic non-acid reflux as impedance events > 80, acid exposure time < 4%, and positive symptom correlation on a standard 24-h pH/impedance test. Other groups not meeting this criteria also deserve consideration depending on the clinical situation. Potential treatments include lifestyle modification, increased acid suppression, alginates, treatment of esophageal hypersensitivity, baclofen, buspirone, prokinetics, and anti-reflux surgery in highly selected individuals. More research is needed to clarify appropriate classification, with subsequent focus on targeted treatments.

Mucosal impedance for esophageal disease: evaluating the evidence

Impedance has traditionally been employed in esophageal disease as a means to assess bolus flow and reflux episodes. Recent and ongoing research has provided new and novel applications for this technology. Measurement of esophageal mucosal impedance, via either multichannel intraluminal impedance catheters or specially designed endoscopically deployed impedance catheters, provides a marker of mucosal integrity. Mucosal impedance has been shown to segregate gastroesophageal reflux disease (GERD) and eosinophilic esophagitis from non-GERD controls and may play a role in predicting response to reflux intervention. More data are needed with regard to other esophageal subgroups, outcome studies, and functional disease. Our paper reviews the history of impedance in esophageal disease, the means of assessing baseline and mucosal impedance, data with regard to the newly developed mucosal impedance probes, the clinical utility of mucosal impedance in specific clinical conditions, and limitations in our existing knowledge, along with suggestions for future studies.

Vagus Nerves Provide a Robust Afferent Innervation of the Mucosa Throughout the Body of the Esophagus in the Mouse

The vagal afferent nerves regulate swallowing and esophageal motor reflexes. However, there are still gaps in the understanding of vagal afferent innervation of the esophageal mucosa. Anatomical studies found that the vagal afferent mucosal innervation is dense in the upper esophageal sphincter area but rare in more distal segments of the esophagus. In contrast, electrophysiological studies concluded that the vagal afferent nerve fibers also densely innervate mucosa in more distal esophagus. We hypothesized that the transfection of vagal afferent neurons with adeno-associated virus vector encoding green fluorescent protein (AAV-GFP) allows to visualize vagal afferent nerve fibers in the esophageal mucosa in the mouse. AAV-GFP was injected into the vagal jugular/nodose ganglia in vivo to sparsely label vagal afferent nerve fibers. The esophageal tissue was harvested 4-6 weeks later, the GFP signal was amplified by immunostaining, and confocal optical sections of the entire esophagi were obtained. We found numerous GFP-labeled fibers in the mucosa throughout the whole body of the esophagus. The GFP-labeled mucosal fibers were located just beneath the epithelium, branched repeatedly, had mostly longitudinal orientation, and terminated abruptly without forming terminal structures. The GFP-labeled mucosal fibers were concentrated in random areas of various sizes in which many fibers could be traced to a single parental axon. We conclude that the vagus nerves provide a robust afferent innervation of the mucosa throughout the whole body of the esophagus in the mouse. Vagal mucosal fibers may contribute to the sensing of intraluminal content and regulation of swallowing and other reflexes.

Randomised clinical trial: the effectiveness of Gaviscon Advance vs non-alginate antacid in suppression of acid pocket and post-prandial reflux in obese individuals after late-night supper

BACKGROUND

Late-night supper increases the risk of postprandial reflux from the acid pocket especially in obesity. An alginate-based, raft-forming medication may be useful for obese patients with GERD.

AIMS

To compare the efficacy of Gaviscon Advance (Reckitt Benckiser, UK) and a non-alginate antacid in post-supper suppression of the acid pocket and post-prandial reflux among obese participants.

METHODS

Participants underwent 48 h wireless and probe-based pH-metry recording of the acid pocket and lower oesophagus, respectively, and were randomised to single post-supper (10 pm) dose of either Gaviscon Advance or a non-alginate antacid on the second night. Primary outcomes were suppression of median pH of acid pocket and lower oesophagus, measured every 10-minutes post-supper for 1 h. Secondary outcomes were suppression of % time pH < 4 at lower oesophagus and improvement in frequency and visual analogue score (VAS) of regurgitation.

RESULTS

Of the 81 screened participants, 55 were excluded and 26 (mean age 33.5 years, males 77.8% and BMI 32.8 kg/m² ) were randomised to Gaviscon Advance (n = 13) or antacid (n = 13). Median pH of the acid pocket but not the lower oesophagus was suppressed with Gaviscon Advance vs antacid (all P < 0.04) Gaviscon Advance but not antacid significantly reduced in % time pH < 4, symptom frequency and VAS on day 2 vs day 1 (all P < 0.05).

CONCLUSIONS

Among obese individuals, Gaviscon Advance was superior to a non-alginate antacid in post-supper suppression of the acid pocket. (Clinical trial registration unique identifier: NCT03516188).

Changes in specific esophageal neuromechanical wall states are associated with conscious awareness of a solid swallowed bolus in healthy subjects

Esophageal neuromechanical wall states are the physical manifestations of circular muscle inhibition and contraction resulting from neural inputs and leading to bolus propulsion. A novel method infers esophageal neuromechanical wall states through simultaneous determination of pressure and diameter in vivo using impedance manometry. We hypothesized that changes in esophageal neuromechanical wall states relate to conscious awareness of esophageal bolus passage ("bolus perception"). Seven healthy participants were selected for perception of solid bolus passage and were compared with seven healthy participants with no conscious awareness of solid bolus passage. Participants were studied using impedance manometry (MMS Solar, Unisensor, 20 Hz). Subjects swallowed ten 5-ml liquid and ten 2-cm square saline-soaked bread boluses and rated bolus perception using a visual analog scale. Esophageal neuromechanical wall states were calculated and analyzed. Proportions of time spent in states with and without luminal distension were compared using a two-proportions Z-test. Bolus perception was associated with neuromechanical wall states corresponding to luminal distension more frequently than matching states without distension in the proximal esophagus (P < 0.001) and transition zone (P < 0.001), whereas there were no differences for the distal esophagus. In healthy volunteers, perceived swallows relate to changes in esophageal neuromechanical wall states in the proximal esophagus. We postulate that these changes relate to bolus retention and summation of active and passive wall tension activating intramural tension receptors.NEW & NOTEWORTHY This study explores esophageal neuromechanical wall states derived from changes in pressure and impedance-derived distension in relation to conscious awareness of esophageal solid bolus transit in healthy volunteers. There are increases in neuromechanical wall states indicative of esophageal distension in healthy volunteers with conscious awareness of bolus transit as compared with unaware individuals. Bolus-based esophageal distension is postulated as a mechanism for esophageal symptoms such as dysphagia.

Pathophysiology, diagnosis, and pharmacological treatment of gastro-esophageal reflux disease

INTRODUCTION

Gastro-esophageal reflux disease (GERD) is a highly prevalent, chronic, relapsing disorder, whose knowledge has increased in last years thanks to the advent of new sophisticated techniques, such as 24-h impedance-pH monitoring and high-resolution manometry, for the study of esophageal functions.

AREAS COVERED

This review provides an overview of our advancements in understanding the complex pathophysiology, improving the diagnosis and defining the modern pharmacological therapeutic approach to GERD.

EXPERT OPINION

The growing clinical application of impedance-pH testing has allowed us to know the diversity of patients with non-erosive reflux disease (NERD), who nowadays represent about 70% of the whole population with reflux symptoms. We have realized that NERD has to be considered as an umbrella term covering various subgroups with different pathophysiologies. The development of new impedance metrics, in particular mean nocturnal baseline impedance, seems to be promising in the improvement of the diagnostic process of this disease. There are no particularly innovative features in the pharmacological therapy of GERD, unless the interest toward drugs is able to increase the defense properties of esophageal mucosa and/or its protection. These compounds can be of help in combination with proton pump inhibitors in NERD patients with partial response to antisecretory drugs alone.

ORAL AND PHARYNGEAL TRANSIT IN FUNCTIONAL HEARTBURN

BACKGROUND

Gastroesophageal reflux disease is associated with slower transit of the bolus through the pharynx and upper esophageal sphincter. Functional heartburn has similar symptoms to gastroesophageal reflux disease, however, the symptoms are not caused by reflux.

OBJECTIVE

The aim of this investigation was to evaluate oral and pharyngeal transit in patients with functional heartburn, with the hypothesis that, similar to patients with gastroesophageal reflux disease, they have changes in pharyngeal and upper esophageal sphincter transit time.

METHODS

Oral and pharyngeal transit was evaluated by videofluoroscopy in eight women with functional heartburn, five with mild dysphagia for solid foods, and 12 female controls. Controls and patients swallowed in duplicate 5 mL and 10 mL of liquid and paste boluses.

RESULTS

No difference in the oral or pharyngeal transit time was found between patients and controls. No aspiration of bolus into the airways was detected in any individual. Pharyngeal residues were detected in the same proportion of swallows, in patients (12.5%) and controls (15.0%), after swallows of 10 mL paste bolus.

CONCLUSION

Oral, pharyngeal and upper esophageal sphincter transit time are similar in patients with functional heartburn to healthy controls.

Phenotypes of Gastroesophageal Reflux Disease: Where Rome, Lyon, and Montreal Meet

Gastroesophageal reflux disease (GERD) is now one of the most common diagnoses made in a gastroenterology practice. From a conventional pathophysiological perspective, GERD is conceptualized as incompetence of the antireflux barrier at the esophagogastric junction; the more severe that incompetence, the worse the disease. However, it is increasingly clear that many presentations of GERD represent distinct phenotypes with unique predisposing cofactors and pathophysiology outside of this paradigm. Three major consensus initiatives have grappled with this dilemma (the Montreal Consensus, The Rome Foundation, and the Lyon Consensus), each from a different perspective. Montreal struggled to define the disease, Rome sought to characterize its functional attributes, while Lyon examined its physiological attributes. Here, we merge the 3 perspectives, developing the concept that what has come to be known as GERD is actually a family of syndromes with a complex matrix of contributing pathophysiology. A corollary to this is that the concept of one size fits all to therapeutics does not apply, and that although escalating treatment with proton pump inhibitors (PPIs) may be pertinent to healing esophagitis, its applicability beyond that is highly questionable. Similarly, failing to recognize the modulating effects of anxiety, hypervigilance, and visceral and central hypersensitivity on symptom severity has greatly oversimplified the problem. That oversimplification has led to excessive use of PPIs for everything captured under the GERD umbrella and shown a broad spectrum of syndromes less amenable to PPI therapy in any dose. It is with this in mind that we delineate this precision medicine concept of GERD.

New Developments in the Diagnosis and Management of Gastroesophageal Reflux

PURPOSE OF REVIEW

To examine recent key developments in the pathophysiology, diagnosis, and treatment of gastroesophageal reflux disease (GERD).

RECENT FINDINGS

Newer research has suggested cytokine-mediated inflammation may play a role in the physiology of GERD, implying that the underlying mechanism may not be entirely related to chemical damage due to acid. Aided by novel technologies, diagnostic testing is also moving toward elucidating individual mechanisms and better defining specific GERD phenotypes with the goal of providing directed therapy. This is especially important in current times given the increase in coverage of adverse events reportedly linked to long-term proton pump inhibitor use.

SUMMARY

As patients are looking for potential alternatives, we highlight the key recent updates in pathophysiology and understanding of GERD and current medical and endoscopic/surgical options and explore the exciting treatments in the pipeline.

Polysaccharide from Gracilaria caudata protects the human esophageal mucosal barrier: A differential topical effect and structural dependence

This study aimed to evaluate the in vitro protective effect of topical treatment with a native sulfated polysaccharide of G. caudata (SP-Gc), hydrolyzed (H-SP-Gc), or desulfated (D-SP-Gc) polysaccharide of Gracilaria caudata in esophageal biopsies obtained from GERD patients. Biopsies were obtained from nonerosive reflux disease (NERD) patients and from erosive esophagitis patients. Then, the biopsies were mounted in an Ussing chamber to measure the basal transepithelial electrical resistance (TEER). The effect of mucosal exposure to an acid solution on TEER was analyzed with or without different concentrations (1, 0.3 or 1%) of SP-Gc, H-SP-Gc, or D-SP-Gc, precoated on the mucosa. Basal esophageal mucosal electrical resistance was significantly lower in erosive esophagitis than from NERD. Mucosal samples precoated with native SP-Gc (1%) significantly prevented TEER drop induced by an acidic solution in NERD, but this effect was not observed in erosive esophagitis. Topical application of D-SP-Gc showed no difference compared to native SP-Gc. However, when treated with chemically-modified SP-Gc, the protective effect observed with native SP-Gc was lost. The present study indicated that SP-Gc protects the human esophageal mucosal barrier in NERD patients. This effect is dependent on the structure but is independent of the presence of sulfate.

Prevalence of non-obstructive dysphagia in patients with heartburn and regurgitation

OBJECTIVE

Heartburn and regurgitation are the most common gastroesophageal reflux symptoms, and dysphagia could be a possible symptom. This investigation aimed to evaluate the prevalence of non-obstructive dysphagia in patients with heartburn and regurgitation.

METHODS

A total of 147 patients (age, 20-70 years; women, 72%) complaining of heartburn and regurgitation, without esophageal stricture, previous esophageal surgery, or other diseases, were evaluated. Twenty-seven patients had esophagitis. The Eating Assessment Tool (EAT-10) was employed to screen for dysphagia; EAT-10 is composed of 10 items, and the patients rate each item from 0 to 4 (0, no problems; 4, most severe symptom). Results of the 147 patients were compared with those of 417 healthy volunteers (women, 62%; control group) aged 20-68 years.

RESULTS

In the control group, only two (0.5%) had an EAT-10 score ≥5, which was chosen as the threshold to define dysphagia. EAT-10 scores ≥5 were found in 71 (48.3%) patients and in 55% of the patients with esophagitis and 47% of the patients without esophagitis. This finding indicates a relatively higher prevalence of perceived dysphagia in patients with heartburn and regurgitation and in patients with esophagitis. We also found a positive correlation between EAT-10 scores and the severity of gastroesophageal reflux symptoms based on the Velanovich scale.

CONCLUSION

In patients with heartburn and regurgitation symptoms, the prevalence of dysphagia was at least 48%, and has a positive correlation with the overall symptoms of gastroesophageal reflux.

Stretta procedure versus proton pump inhibitors for the treatment of nonerosive reflux disease: A 6-month follow-up

To compare the Stretta procedure with proton pump inhibitors for the treatment of nonerosive reflux disease (NERD).From July 2018 to April 2019, patients diagnosed with NERD and referred for treatment were enrolled. They were treated with either Stretta procedure or proton pump inhibitor (PPI) medication and followed-up for 6 months. The symptom control, quality of life, lower esophageal sphincter (LES) pressure, 24-hour pH parameters, PPI usage and satisfaction rate were evaluated. The complications were assessed. The outcomes of the 2 groups were analyzed and compared.Twenty-eight patients in the Stretta group and 21 patients in the PPI group completed the 6-month follow-up. No severe adverse events occurred in both groups. Both interventions were effective in improvement of symptom and quality of life. The symptom score improvement was significantly superior in the Stretta group compared to the PPI group (6.3 ± 3.4 vs 8.5 ± 4.1, P = .03). LES pressure increased significantly in the Stretta group compared to the PPI group (14.2 ± 4.4 mm Hg vs 10.0 ± 4.0 mm Hg, P < .01). Although both interventions improved 24-hour pH parameters, including number of acid episodes (P = .27), acid exposure time (P = .39), and DeMeester score (P = .28), no difference was found between the 2 groups. Complete PPI cessation rate (82% vs 52%, P = .03) as well as satisfaction rate (89% vs 57%, P = .02) was much higher in Stretta group than those in the PPI groupThe Stretta procedure was safe and effective in the short term for the management of NERD. The Stretta procedure resulted in higher LES pressure and achieved better improvement of symptom control and PPI cessation than did PPI in the short term.

Neuronal Control of Esophageal Peristalsis and Its Role in Esophageal Disease

PURPOSE OF REVIEW

Esophageal peristalsis is a highly sophisticated function that involves the coordinated contraction and relaxation of striated and smooth muscles in a cephalocaudal fashion, under the control of central and peripheral neuronal mechanisms and a number of neurotransmitters. Esophageal peristalsis is determined by the balance of the intrinsic excitatory cholinergic, inhibitory nitrergic and post-inhibitory rebound excitatory output to the esophageal musculature.

RECENT FINDINGS

Dissociation of the longitudinal and circular muscle contractions characterizes different major esophageal disorders and leads to esophageal symptoms. Provocative testing during esophageal high-resolution manometry is commonly employed to assess esophageal body peristaltic reserve and underpin clinical diagnosis. Herein, we summarize the main factors that determine esophageal peristalsis and examine their role in major and minor esophageal motility disorders and eosinophilic esophagitis.

Gastric inlet patches: symptomatic or silent?

PURPOSE OF REVIEW

The purpose of this review is to assess recent literature on the clinical relevance of the gastric inlet patch with particular focus on endoscopic diagnosis and treatment, the relationship of the inlet patch to laryngopharyngeal reflux disease and the association of proximal esophageal adenocarcinoma with inlet patch.

RECENT FINDINGS

Recent studies suggest endoscopic diagnosis of inlet patch increases with endoscopist awareness (up to 10-fold) and when using enhanced imaging techniques such as narrow band imaging (up to three-fold). The literature remains mixed on the association of inlet patch with laryngopharyngeal symptoms or globus sensation. Studies of endoscopic ablation, using argon plasma coagulation or radiofrequency ablation have shown improved laryngopharyngeal reflux symptom scores posttreatment. Proximal esophageal adenocarcinomas are rare but often associated with inlet patch when they occur. Case studies have described endoscopic resection of malignant lesions related to inlet patch, using endoscopic mucosal resection or submucosal dissection.

SUMMARY

Prospective, multicenter studies of symptom association with inlet patch using validated symptom questionnaires and blinded sham-controlled treatments are needed to further clarify the role of such treatments, which to date are limited to a small numbers of centers with a special interest.

Reflux esophagitis, functional and non-functional

The pathogenesis of gastroesophageal reflux disease has been explained by acid-peptic model. However, related with the progress of the diagnostic modalities, another phenotypical group of patients were defined and called "functional disorders of the esophagus". These patients are important because diagnosis is particularly difficult, co-morbid disorders especially psychiatric diseases are common, proton pump inhibitor response is low, and surgical results are very poor. Simpler and translational science studies are required in functional groups in order to differentiate from acid-peptic disorders. New and more accurate diagnostic modalities as well as therapeutic approaches are strongly needed in this particularly new and exciting era, especially in the effect of neuromodulators. Current diagnostic modalities should also be evaluated and in fact, normal values should be established. New medications, especially acting at the level of esophageal epithelium and intercellular spaces, might shift the paradigm.

Esophageal mucosal innervation in functional heartburn: Closer to healthy asymptomatic subjects than to non-erosive reflux disease patients

BACKGROUND

Mucosal innervation in non-erosive reflux disease (NERD; pathological esophageal acid exposure, normal macroscopic mucosa) is clearly distinct from that of healthy volunteers (HV) and from patients with esophagitis or Barrett's esophagus: The nerves in NERD are situated much closer to the luminal surface of the mucosa. Patients with functional heartburn (FH) have a similar symptom profile to patients with NERD and indistinguishable macroscopic appearances. However, they have physiological acid exposure and no reflux-symptom association. The aim of our study was to delineate the position of esophageal mucosal nerve fibers in patients with FH and compare it with that in NERD and HV.

METHODS

Distal esophageal biopsies from patients with FH were immunohistochemically stained for CGRP. CGRP-positive nerve fibers were identified, and their position relative to the lumen was determined. These results were compared to our previously published cohort of HV and NERD.

RESULTS

Eleven patients were included in the FH group with a mean age of 46 years (range 33-69); 7F:4M. Nine patients had visible nerve fibers. The location of the afferent nerve fibers in the distal esophageal mucosa (median of 22, range 10.4-28) was similar to the HV group (median 25.5) and significantly deeper than the superficial nerves seen in NERD (median 9.5).

CONCLUSIONS

The mucosal innervation pattern in FH is more alike that of healthy individuals than that of NERD, with afferent nerves lying deep in the mucosa, away from the luminal surface. This supports the theory that heartburn in FH has a distinct nociceptive pathophysiology.

Revisiting Montreal: New Insights into Symptoms and Their Causes, and Implications for the Future of GERD

The Montreal definition of gastroesophageal reflux disease (GERD) provided a rationale for acid suppression medication without investigation, thus enhancing the management of the substantial symptom burden in these patients. Increased proton-pump inhibitor use has also highlighted their limitations, with one third of "typical" symptoms known to be refractory. Most refractory symptoms are ascribed to reflux hypersensitivity (RH) and functional heartburn (FH). RH may be caused by impaired esophageal mucosal barrier function and sensitization of peripheral esophageal receptors. Central sensitization may also contribute to the perception of non-pathologic reflux in RH, and the perception of physiological stimuli in FH. Importantly, mechanisms underlying GERD, RH, and FH are (in theory) not mutually exclusive, further complicating patient management. Methods used to distinguish GERD from RH and FH are impractical for use in epidemiological studies and pragmatic care and may have limited diagnostic accuracy. This is impeding accurate prevalence estimates and risk factor determination and the identification of new therapies. Direct assessment of mucosal barrier function by measuring impedance is a promising candidate for improved diagnosis. Ultimately though the concept of GERD as a composite, symptom-based entity needs re-evaluation, so that new understandings of upper GI symptoms can direct more precise management.