Prevalence of gastroesophagopharyngeal acid reflux events: an evidence-based systematic review

Diagnosis of Laryngopharyngeal Reflux: Past, Present, and Future-A Mini-Review

Laryngopharyngeal reflux (LPR) is a variant of gastroesophageal reflux disease (GERD) in which gastric refluxate irritates the lining of the aerodigestive tract and causes troublesome airway symptoms or complications. LPR is a prevalent disease that creates a significant socioeconomic burden due to its negative impact on quality of life, tremendous medical expense, and possible cancer risk. Although treatment modalities are similar between LPR and GERD, the diagnosis of LPR is more challenging than GERD due to its non-specific symptoms/signs. Due to the lack of pathognomonic features of endoscopy, mounting evidence focused on physiological diagnostic testing. Two decades ago, a dual pH probe was considered the gold standard for detecting pharyngeal acidic reflux episodes. Despite an association with LPR, the dual pH was unable to predict the treatment response in clinical practice, presumably due to frequently encountered artifacts. Currently, hypopharygneal multichannel intraluminal impedance-pH catheters incorporating two trans-upper esophageal sphincter impedance sensors enable to differentiate pharyngeal refluxes from swallows. The validation of pharyngeal acid reflux episodes that are relevant to anti-reflux treatment is, therefore, crucial. Given no diagnostic gold standard of LPR, this review article aimed to discuss the evolution of objective diagnostic testing and its predictive role of treatment response.

The Role of PARP ‐1 and NF‐κB in Bile‐Induced DNA Damage and Oncogenic Profile in Hypopharyngeal Cells

OBJECTIVES/HYPOTHESIS

We recently documented that acidic bile, a gastroesophageal reflux content, can cause invasive hypopharyngeal squamous cell carcinoma, by inducing widespread DNA damage and promoting nuclear factor kappa B (NF-κB)-related oncogenic molecular events. Poly or adenosine diphosphate (ADP)-ribose polymerase-1 (PARP-1), a sensitive sensor of DNA damage, may interact with NF-κB. We hypothesized that PARP-1 is activated in hypopharyngeal cells (HCs) with marked DNA damage caused by acidic bile, hence there is an association between PARP-1 and NF-κB activation or its related oncogenic profile, in this process.

STUDY DESIGN

In vitro study.

METHODS

We targeted PARP-1 and NF-κB(p65), using pharmacologic inhibitors, 1.0 μM Rucaparib (AG014699) and 10 μM BAY 11-7082 {3-[4=methylphenyl)sulfonyl]-(2E)-propenenitrile}, respectively, or silencing their gene expression (siRNAs) and used immunofluorescence, luciferase, cell viability, direct enzyme-linked immunosorbent assays, and qPCR analysis to detect the effect of targeting PARP-1 or NF-κB in acidic bile-induced DNA damage, PARP-1, p-NF-κB, and B-cell lymphoma 2 (Bcl-2) expression, as well as NF-κB transcriptional activity, cell survival, and mRNA oncogenic phenotype in HCs.

RESULTS

We showed that (i) PARP-1 is overexpressed by acidic bile, (ii) targeting NF-κB adequately prevents the acidic bile-induced DNA double-strand breaks (DSBs) by gamma H2A histone family member X (γH2AX), oxidative DNA/RNA damage, PARP-1 overexpression, anti-apoptotic mRNA phenotype, and cell survival, whereas (iii) targeting PARP-1 preserves elevated DNA damage, NF-κB activation, and anti-apoptotic phenotype.

CONCLUSION

We document for the first time that the activation of PARP-1 is an early event during bile reflux-related head and neck carcinogenesis and that NF-κB can mediate DNA damage and PARP-1 activation. Our data encourage further investigation into how acidic bile-induced activated NF-κB mediates DNA damage in hypopharyngeal carcinogenesis.

LEVEL OF EVIDENCE

NA Laryngoscope, 133:1146-1155, 2023.

Bile reflux and hypopharyngeal cancer (Review)

Laryngopharyngeal reflux, a variant of gastroesophageal reflux disease, has been considered a risk factor in the development of hypopharyngeal cancer. Bile acids are frequently present in the gastroesophageal refluxate and their effect has been associated with inflammatory and neoplastic changes in the upper aerodigestive tract. Recent in vitro and in vivo studies have provided direct evidence of the role of acidic bile refluxate in hypopharyngeal carcinogenesis and documented the crucial role of NF-κB as a key mediator of early oncogenic molecular events in this process and also suggested a contribution of STAT3. Acidic bile can cause premalignant changes and invasive squamous cell cancer in the affected hypopharynx accompanied by DNA damage, elevated p53 expression and oncogenic mRNA and microRNA alterations, previously linked to head and neck cancer. Weakly acidic bile can also increase the risk for hypopharyngeal carcinogenesis by inducing DNA damage, exerting anti-apoptotic effects and causing precancerous lesions. The most important findings that strongly support bile reflux as an independent risk factor for hypopharyngeal cancer are presented in the current review and the underlying mechanisms are provided.

Pepsin Promotes Activation of Epidermal Growth Factor Receptor and Downstream Oncogenic Pathways, at Slightly Acidic and Neutral pH, in Exposed Hypopharyngeal Cells

Pepsin refluxate is considered a risk factor for laryngopharyngeal carcinogenesis. Non-acidic pepsin was previously linked to an inflammatory and tumorigenic effect on laryngopharyngeal cells in vitro. Yet there is no clear evidence of the pepsin-effect on a specific oncogenic pathway and the importance of pH in this process. We hypothesized that less acidic pepsin triggers the activation of a specific oncogenic factor and related-signalling pathway. To explore the pepsin-effect in vitro, we performed intermittent exposure of 15 min, once per day, for a 5-day period, of human hypopharyngeal primary cells (HCs) to pepsin (1 mg/mL), at a weakly acidic pH of 5.0, a slightly acidic pH of 6.0, and a neutral pH of 7.0. We have documented that the extracellular environment at pH 6.0, and particularly pH 7.0, vs. pH 5.0, promotes the pepsin-effect on HCs, causing increased internalized pepsin and cell viability, a pronounced activation of EGFR accompanied by NF-κB and STAT3 activation, and a significant upregulation of EGFR, AKT1, mTOR, IL1β, TNF-α, RELA(p65), BCL-2, IL6 and STAT3. We herein provide new evidence of the pepsin-effect on oncogenic EGFR activation and its related-signaling pathway at neutral and slightly acidic pH in HCs, opening a window to further explore the prevention and therapeutic approach of laryngopharyngeal reflux disease.

Weakly Acidic Bile Is a Risk Factor for Hypopharyngeal Carcinogenesis Evidenced by DNA Damage, Antiapoptotic Function, and Premalignant Dysplastic Lesions In Vivo

Simple Summary

The etiologic role of biliary reflux in hypopharyngeal cancer is supported by clinical data. Although, reflux episodes often occur at pH 4.0, they can also occur at weakly acidic pH (5.5–6.0). The carcinogenic effect of bile at strongly acidic pH (pH 3.0) was recently documented in vivo. Here, we provide novel in vivo evidence that a weakly acidic pH of 5.5, similarly to a strongly acidic pH of 3.0, increases the risk of bile-related hypopharyngeal neoplasia. We document that chronic exposure of hypopharyngeal mucosa to bile at pH 5.5 promotes premalignant lesions with DNA damage, NF-κB activation, and deregulated mRNA and miRNA phenotypes, including Bcl-2 and miR-451a. The oncogenic effects of bile over a wider pH range suggests that antacid therapy may be insufficient to fully modify the effects of a bile induced oncogenic effect.

Abstract

Background: There is recent in vivo discovery documenting the carcinogenic effect of bile at strongly acidic pH 3.0 in hypopharynx, while in vitro data demonstrate that weakly acidic bile (pH 5.5) has a similar oncogenic effect. Because esophageal refluxate often occurs at pH > 4.0, here we aim to determine whether weakly acidic bile is also carcinogenic in vivo. Methods: Using 32 wild-type mice C57B16J, we performed topical application of conjugated primary bile acids with or without unconjugated secondary bile acid, deoxycholic acid (DCA), at pH 5.5 and controls, to hypopharyngeal mucosa (HM) twice per day, for 15 weeks. Results: Chronic exposure of HM to weakly acidic bile, promotes premalignant lesions with microinvasion, preceded by significant DNA/RNA oxidative damage, γH2AX (double strand breaks), NF-κB and p53 expression, overexpression of Bcl-2, and elevated Tnf and Il6 mRNAs, compared to controls. Weakly acidic bile, without DCA, upregulates the “oncomirs”, miR-21 and miR-155. The presence of DCA promotes Egfr, Wnt5a, and Rela overexpression, and a significant downregulation of “tumor suppressor” miR-451a. Conclusion: Weakly acidic pH increases the risk of bile-related hypopharyngeal neoplasia. The oncogenic properties of biliary esophageal reflux on the epithelium of the upper aerodigestive tract may not be fully modified when antacid therapy is applied. We believe that due to bile content, alternative therapeutic strategies using specific inhibitors of relevant molecular pathways or receptors may be considered in patients with refractory GERD.

Biliary tumorigenic effect on hypopharyngeal cells is significantly enhanced by pH reduction

Biliary reflux has been considered a potential risk factor in upper aerodigestive tract malignancies. It is not yet clearly known how pH affects the bile-induced activation of NF-κB and its related oncogenic pathway previously linked to hypopharyngeal carcinogenesis. In this study, repetitive applications of conjugated primary bile acids with unconjugated secondary bile acid, deoxycholic acid (DCA), on human hypopharyngeal primary cells reveal that strongly acidic pH (4.0) optimally enhances the tumorigenic effect of bile, by inducing activation of NF-κB, STAT3 nuclear translocation, bcl-2 overexpression and significant overexpression of the oncogenic mRNA phenotype, compared to weakly acidic pH (5.5) or neutral pH (7.0). As the pH becomes less acidic the partially activated primary bile acids and activated DCA begin to exert their influence; however, with significantly less intensity compared to bile acids at strongly acidic pH. Our findings suggest that biliary tumorigenic effect is strongly pH dependent. Controlling pH during reflux events may be therapeutically effective in reducing the potential risk of bile-induced hypopharyngeal cancer.

Inhibition of NF-κB prevents the acidic bile-induced oncogenic mRNA phenotype, in human hypopharyngeal cells

Bile-containing gastro-duodenal reflux has been clinically considered an independent risk factor in hypopharyngeal carcinogenesis. We recently showed that the chronic effect of acidic bile, at pH 4.0, selectively induces NF-κB activation and accelerates the transcriptional levels of genes, linked to head and neck cancer, in normal hypopharyngeal epithelial cells. Here, we hypothesize that NF-κB inhibition is capable of preventing the acidic bile-induced and cancer-related mRNA phenotype, in treated normal human hypopharyngeal cells. In this setting we used BAY 11-7082, a specific and well documented pharmacologic inhibitor of NF-κB, and we observed that BAY 11-7082 effectively inhibits the acidic bile-induced gene expression profiling of the NF-κB signaling pathway (down-regulation of 72 out of 84 analyzed genes). NF-κB inhibition significantly prevents the acidic bile-induced transcriptional activation of NF-κB transcriptional factors, RELA (p65) and c-REL, as well as genes related to and commonly found in established HNSCC cell lines. These include anti-apoptotic bcl-2, oncogenic STAT3, EGFR, ∆Np63, TNF-α and WNT5A, as well as cytokines IL-1β and IL-6. Our findings are consistent with our hypothesis demonstrating that NF-κB inhibition effectively prevents the acidic bile-induced cancer-related mRNA phenotype in normal human hypopharyngeal epithelial cells supporting an understanding that NF-κB may be a critical link between acidic bile and early preneoplastic events in this setting.

Pharyngeal pH monitoring in infants with laryngitis

Objective

To assess pharyngeal acid reflux (PAR) exposure with flexible laryngoscopy-guided pharyngeal pH monitoring in infants with laryngitis.

Study Design

Tertiary care children's hospital.

Subjects and Methods

Charts of 10 infants with laryngitis who underwent pharyngoesophageal pH monitoring were reviewed. Data included history, physical examination, and pharyngoesophageal pH monitoring findings.

Results

Six infants had PAR. Two patients were on acid suppressive therapy and exhibited PAR. The number of PAR observed in six infants ranged between 1 and 81. The percent acid exposure time (AET) in the pharynx was between 0.1% and 1.2%. Esophageal acid reflux documented in nine infants ranged between 5 and 173. The percent AET in the esophagus was between 0.1% and 4.8%.

Conclusions

The majority of the studied infants with laryngitis had PAR. Not all esophageal acid reflux reached the pharynx. Pharyngeal pH monitoring provides additional information that cannot be obtained with esophageal pH monitoring in infants with laryngitis.

Proton pump inhibitors and histamine 2 blockers are associated with improved overall survival in patients with head and neck squamous carcinoma

It has been postulated that gastroesophageal reflux plays a role in the etiology of head and neck squamous cell carcinomas (HNSCC) and contributes to complications after surgery or during radiotherapy. Antacid medications are commonly used in patients with HNSCC for the management of acid reflux; however, their relationship with outcomes has not been well studied. Associations between histamine receptor-2 antagonists (H2RA) and proton pump inhibitors (PPI) use and treatment outcomes were determined in 596 patients with previously untreated HNSCC enrolled in our SPORE epidemiology program from 2003 to 2008 (median follow-up 55 months). Comprehensive clinical information was entered prospectively in our database. Risk strata were created on the basis of possible confounding prognostic variables (age, demographics, socioeconomics, tumor stage, primary site, smoking status, HPV16 status, and treatment modality); correlations within risk strata were analyzed in a multivariable model. Patients taking antacid medications had significantly better overall survival (OS; PPI alone: P < 0.001; H2RA alone, P = 0.0479; both PPI + H2RA, P = 0.0133). Using multivariable Cox models and adjusting for significant prognostic covariates, both PPIs and H2RAs used were significant prognostic factors for OS, but only H2RAs use for recurrence-free survival in HPV16-positive oropharyngeal patients. We found significant associations between the use of H2RAs and PPIs, alone or in combination, and various clinical characteristics. The findings in this large cohort study indicate that routine use of antacid medications may have significant therapeutic benefit in patients with HNSCC. The reasons for this association remain an active area of investigation and could lead to identification of new treatment and prevention approaches with agents that have minimal toxicities.

Classical reflux symptoms, hiatus hernia and overweight independently predict pharyngeal acid exposure in patients with suspected reflux laryngitis

BACKGROUND

Gastro-oesophageal reflux disease (GERD) has been associated with reflux laryngitis.

AIMS

To investigate the risk factors and the predictors of pharyngeal acid reflux (PAR) in Taiwanese patients with suspected reflux laryngitis.

METHODS

With referral from ENT physicians, 104 patients with symptoms and signs suggestive of reflux laryngitis completed a validated symptom questionnaire, an upper endoscopy exam and ambulatory 24-h pH tests with three sensors located at the hypopharynx, proximal and distal oesophagus. Patients with one or more episodes of PAR were considered abnormal.

RESULTS

Pharyngeal acid reflux was identified in 17% (18/104) of patients. In multivariate logistic regression analysis, PAR was independently associated with classical reflux symptoms [adjusted odds ratio (aOR) = 3.5, 95% confidence interval (CI): 1.0-12.8], hiatus hernia (aOR = 6.7, 95% CI: 1.5-30.2) and overweight (aOR = 3.4, 95% CI: 1.0-11.0). In predicting PAR, classical reflux symptoms had a sensitivity of 78% and hiatus hernia had a specificity of 95%. With all three factors, the positive predictive value for PAR was 80%. Classical reflux symptoms included heartburn, chest pain, dyspepsia and acid regurgitation.

CONCLUSIONS

Classical reflux symptoms, hiatus hernia and overweight are independent risk factors that may predict pharyngeal acid reflux in patients with suspected reflux laryngitis.

Ambulatory 24-hour pharyngeal pH monitoring in healthy Korean volunteers

Pharyngeal pH monitoring is the standard diagnostic approach for laryngopharyngeal reflux (LPR). However, the normal values for Asian populations are still unknown. We evaluated the results of ambulatory 24-h pharyngeal pH monitoring in healthy volunteers to determine the normal reference values in the Korean population. Thirty healthy subjects underwent ambulatory 24-h pharyngeal pH monitoring with glass electrodes positioned 1 cm above the upper esophageal sphincter and 5 cm above the lower esophageal sphincter, based on esophageal manometry after upper gastrointestinal endoscopy. LPR occurred in about one half of the healthy volunteers without any significant association with age, gender and body mass index. Pharyngeal acid reflux occurred mainly in the upright position. At the 95th and 90th percentile, after the exclusion of mealtimes, the upper limits of normal (ULN) for pharyngeal acid exposure were 0.41% and 0.18%. The ULNs for the number of pharyngeal acid events were 12.8 and 5.0. The corresponding ULNs for the esophagus were 5.1% and 3.8% and 62.7 and 32.6. The findings of this study help establish the reference standards for LPR in Korean patients.

Flexible laryngoscopy-guided pharyngeal pH monitoring in infants

OBJECTIVE

To evaluate flexible laryngoscopy-guided pharyngeal pH probe monitoring as an alternative accurate and practical pharyngeal pH probe placement technique to eliminate the need for radiographs and esophageal manometry for pharyngeal pH monitoring in infants with extraesophageal reflux disease (EERD).

MATERIALS AND METHODS

Infants with suspected laryngopharyngeal acid reflux (LPR) who underwent pharyngoesophageal pH monitoring were included. Data analysis included description of the flexible laryngoscopy-guided pharyngoesophageal pH monitoring technique and pharyngoesophageal pH monitoring findings, including the number of acid reflux episodes and percent acid exposure time.

RESULTS

Six infants (3 boys, 3 girls, age range, 2 wk-7.5 mo) with suspected LPR underwent pharyngoesophageal pH monitoring. Flexible laryngoscopy was used, under direct vision, to guide pH probe placement in the laryngopharyngeal region. The esophageal pH probe was located 5 cm distal to the pharyngeal pH probe. All infants tolerated the procedure. Of the six infants, four had pharyngeal acid reflux, and six had esophageal acid reflux. The number of acid reflux episodes ranged from 4 to 81 in the pharynx and from 5 to 173 in the esophagus. The percentage of acid exposure time was between 0% and 1.2% in the pharynx and between 0.1% and 1.5% in the esophagus.

CONCLUSION

With the aid of flexible laryngoscopy, a pH probe can be placed in the laryngopharyngeal region in infants undergoing pharyngeal pH monitoring. Findings documented that not all esophageal acid reflux reach the pharynx. Flexible laryngoscopy-guided pharyngeal pH probe placement can be used to detect LPR in infants with EERD.

Performance and optimal technique for pharyngeal impedance recording: A simulated pharyngeal reflux study

BACKGROUND AND AIMS

Detection rate, influence of recording site, and subject posture for impedance monitoring of pharyngeal reflux of gastric contents remain unknown. We evaluated the ability of the impedance sensor for detection of various volumes of intrapharyngeal infusate at two sites and in two subject positions.

METHODS

Nineteen healthy subjects were studied using concurrent videoendoscopic, manometric, impedance, and pH recording.

RESULTS

Detection rate of simulated pharyngeal reflux events ranged between 87% and 100% for 1-4 mL. Detection rate for 0.1-1 mL volumes in the upright position was significantly higher (78-85%) when the impedance sensor was located at the proximal margin of the upper esophageal sphincter (UES) compared to 2 cm proximally (38-68%) (P < 0.001). With the sensor at 2 cm above the UES, the average detection rate for all volumes in the upright position was significantly less (P < 0.001) compared to the supine position (48%vs 84%). There was substantial variability in the magnitude of impedance changes induced by different infusates.

CONCLUSIONS

Impedance sensors can detect as small a volume as 0.1 mL and combined with a pH sensor can detect acidic and nonacidic liquid and mist reflux events. Sensor placement at the proximal margin of the UES yields the highest detection rate irrespective of subject posture compared to placement 2 cm proximally. Depending on the volume of refluxate and location of the impedance sensor, a substantial minority of simulated reflux events can be missed.

Relationship between time of exposure of laryngopharyngeal reflux and gene expression in laryngeal fibroblasts

OBJECTIVES

Acid reflux is damaging to the laryngeal mucosa; however, the significance of the duration of reflux episodes has not been evaluated. The purpose of this study was to determine whether varying the exposure times at low pH with or without pepsin alters gene expression in laryngeal fibroblasts.

METHODS

Human false vocal fold and postcricoidal cultures were exposed to pH 4 or pH 5 media with and without pepsin for 10, 30, 60, and 240 seconds. Using a real-time polymerase chain reaction, we determined the messenger RNA expression of TGFbeta-1, VEGF, FGF-2, EGR-1, ATF-3, CTGF, MMP-1, MMP-2, and decorin.

RESULTS

Molecular responses were initiated at pH 5. Postcricoidal fibroblasts were more sensitive than false vocal fold fibroblasts to the presence of pepsin. Changes in transcript levels were dependent on acid exposure time, and the most significant changes were measured during the first 60 seconds after exposure.

CONCLUSIONS

Time of exposure to acid and pepsin needs to be taken into consideration when determining limit of pathology in pharyngeal reflux. Genes are identified that are induced by low pH and that may be of potential importance in the pathogenesis of reflux laryngitis.