Role of saliva in esophageal defense: implications in patients with nonerosive reflux disease

Insight into global burden of gastroesophageal reflux disease: Understanding its reach and impact

The exact worldwide prevalence of gastroesophageal reflux disease (GERD) remains uncertain, despite its recognition as a common condition. This conundrum arises primarily from the lack of a standardized definition for GERD. The gold standard diagnostic tests for GERD, such as pH impedance testing and endoscopy, are cumbersome and impractical for assessing community prevalence. Consequently, most epidemiological studies rely on symptom-based screening tools. GERD symptoms can be both esophageal and extraesophageal, varying widely among individuals. This variability has led to multiple symptom-based definitions of GERD, with no consensus, resulting in prevalence estimates ranging from 5% to 25% worldwide. Most systematic reviews define GERD as experiencing heartburn and/or regurgitation at least once weekly, yielding a calculated prevalence of 13.98%. In 2017, the global age-standardized prevalence of GERD was estimated at 8819 per 100000 people (95% confidence interval: 7781-9863), a figure that has remained stable from 1990 to 2017. Prevalence increases with age, leading to more years lived with disability. GERD significantly impairs quality of life and can lead to multiple complications. Additionally, it imposes a severe economic burden, with the United States alone estimated to spend around 10 billion dollars annually on diagnosis and treatment. In summary, GERD prevalence varies greatly by region and even within different areas of the same province. Determining the exact prevalence is challenging due to inconsistent diagnostic criteria. However, it is well-documented that GERD poses a significant global burden, affecting the quality of life of individuals and creating a substantial healthcare cost.

Microbiota profiling in esophageal diseases: Novel insights into molecular staining and clinical outcomes

Gut microbiota is recognized nowadays as one of the key players in the development of several gastro-intestinal diseases. The first studies focused mainly on healthy subjects with staining of main bacterial species via culture-based techniques. Subsequently, lots of studies tried to focus on principal esophageal disease enlarged the knowledge on esophageal microbial environment and its role in pathogenesis. Gastro Esophageal Reflux Disease (GERD), the most widespread esophageal condition, seems related to a certain degree of mucosal inflammation, via interleukin (IL) 8 potentially enhanced by bacterial components, lipopolysaccharide (LPS) above all. Gram- bacteria, producing LPS), such as Campylobacter genus, have been found associated with GERD. Barrett esophagus (BE) seems characterized by a Gram- and microaerophils-shaped microbiota. Esophageal cancer (EC) development leads to an overturn in the esophageal environment with the shift from an oral-like microbiome to a prevalently low-abundant and low-diverse Gram--shaped microbiome. Although underinvestigated, also changes in the esophageal microbiome are associated with rare chronic inflammatory or neuropathic disease pathogenesis. The paucity of knowledge about the microbiota-driven mechanisms in esophageal disease pathogenesis is mainly due to the scarce sensitivity of sequencing technology and culture methods applied so far to study commensals in the esophagus. However, the recent advances in molecular techniques, especially with the advent of non-culture-based genomic sequencing tools and the implementation of multi-omics approaches, have revolutionized the microbiome field, with promises of implementing the current knowledge, discovering more mechanisms underneath, and giving insights into the development of novel therapies aimed to re-establish the microbial equilibrium for ameliorating esophageal diseases..

Differences in salivary secretion and epidermal growth factor concentrations in mild reflux esophagitis and non-erosive reflux disease

BACKGROUND

Sex differences in salivary secretion have been reported among healthy subjects. In the present study, salivary secretion and salivary epidermal growth factor (EGF) concentrations were investigated in mild reflux esophagitis patients, non-erosive reflux disease (NERD) patients, and healthy controls by matching the sex ratio.

METHODS

Thirty-three (male:female = 11:22) patients with NERD, 33 (11:22) with mild reflux esophagitis, and 33 (11:22) healthy controls were recruited for this case-control study. Salivary secretion was assessed as follows: each patient chewed sugar-free gum for 3 min prior to endoscopy, and the amount of saliva secretion, salivary pH, and salivary pH after acid loading as an index of the acid-buffering capacity were measured. Salivary EGF concentrations were measured by ELISA.

RESULTS

No significant differences were observed in the amount of saliva secretion, salivary pH, or the acid-buffering capacity between the mild reflux esophagitis and NERD groups. However, the amount of saliva secretion and the acid-buffering capacity in the mild reflux esophagitis group and the amount of saliva secretion, salivary pH, and the acid-buffering capacity in the NERD group were significantly lower than those in the healthy control group. No significant differences were noted in salivary EGF concentrations between the mild reflux esophagitis and NERD groups.

CONCLUSION

After matching the sex ratio, the saliva secretion was significantly lower in patients with mild reflux esophagitis and NERD than in healthy controls. However, no significant differences were observed in the amount of saliva secretion or salivary EGF concentrations between both groups.

Expression of VEGF, EGF, and Their Receptors in Squamous Esophageal Mucosa, with Correlations to Histological Findings and Endoscopic Minimal Changes, in Patients with Different GERD Phenotypes

BACKGROUND

Gastroesophageal reflux disease (GERD) may present as nonerosive reflux disease (NERD), erosive esophagitis (EE), or be complicated by Barrett's esophagus (BE). The explanation as to what determines the phenotype of GERD is awaited. Therefore, we assessed the correlation between the growth factors expression and endoscopic as histologic findings in GERD patients.

METHODS

The squamous esophageal epithelium of 50 patients (20-NERD, 7-EE, 15-BE, 8 controls) was examined by: (1) magnification endoscopy with evaluation of minimal GERD changes such as: microerosions, white spots, palisade blood vessels visibility, and intrapapillary capillary loops (IPCLs) appearance, (2) histology, (3) immunohistochemistry with evaluation of the expression of vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), and their receptors (VEGFR and EGFR).

RESULTS

The expression of VEGF, but not VEGFR, EGF, and EGFR, was significantly increased in EE patients compared to NERD patients and controls. VEGF levels correlated significantly with the presence of white spots, but not with other minimal endoscopic and histologic features. The EGFR expression correlated positively with basal cell hyperplasia and enlarged IPCLs.

CONCLUSIONS

Our findings suggest a correlation between growth factors expression and findings in conventional endoscopy, formation of endoscopic minimal changes, and histologic lesions.

Saliva secretion is reduced in mild reflux esophagitis patients

BACKGROUND

Salivary secretion in patients with mild reflux esophagitis has not been examined. In this study, saliva secretion and salivary epidermal growth factor (EGF) in patients with mild reflux esophagitis were investigated.

METHODS

Thirty-eight mild reflux esophagitis patients and 38 control subjects were recruited for this case-control study. Saliva secretion testing was performed. Saliva secretion was assessed as follows: each patient chewed sugar-free gum for 3 min prior to endoscopy, and the volume and pH of saliva before and after acid loading as an index of the acid-buffering capacity were measured. The salivary EGF concentration was assessed by ELISA.

RESULTS

The volume of saliva secreted was significantly (p = 0.0412) lower in the mild reflux esophagitis group than in the control group, with medians (25th-75th percentile) of 4.2 mL/3 min [2.6-6.2] and 6.0 [3.9-8.0], respectively. No significant differences were observed in salivary pH (the mild reflux esophagitis group: 7.1 [6.9-7.2], the control group 7.2 [7.1-7.3]). Salivary pH after acid loading was significantly (p = 0.0009) lower in the mild reflux esophagitis group (5.9 [5.5-6.3]) than in the control group (6.3 [6.2-6.5]). No significant differences were noted in salivary EGF concentrations (the mild reflux esophagitis group: 1739.0 pg/mL [1142.3-3329.0], the control group: 1678.0 [1091.8-2122.5].

CONCLUSION

The secretion volume and acid-buffering capacity of stimulated saliva were reduced in patients with mild reflux esophagitis.

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.

Saliva secretion is reduced in proton pump inhibitor-responsive non-erosive reflux disease patients

BACKGROUND

There is no consensus on the relationship between saliva secretion and non-erosive reflux disease (NERD). In this study, saliva secretion and salivary epidermal growth factor (EGF) in patients with NERD were examined.

METHODS

Thirty-one PPI-responsive NERD patients and 31 control subjects were recruited for this case-control study. Saliva secretion testing was performed. Saliva secretion was assessed as follows: each patient chewed sugar-free gum for 3 min prior to endoscopy, and the amount and pH of saliva before and after acid loading as an index of the acid-buffering capacity were measured. The salivary EGF concentration was assessed by ELISA.

RESULTS

The amount of saliva secreted was significantly lower in the NERD group than in the control group, with medians (25th-75th percentile) of 4.0 mL/3 min (2.0-6.0) and 6.0 (3.9-8.0), respectively (p = 0.0131). Salivary pH was significantly lower in the NERD group (7.0 [6.8-7.2]) than in the control group (7.2 [7.0-7.3], p = 0.0100). Salivary pH after acid loading was significantly lower in the NERD group (5.8 [5.4-6.2]) than in the control group (6.3 [6.1-6.5], p = 0.0002). The difference in pH of stimulated saliva after acid loading (1.2 [0.9-1.5], p = 0.0021) was significantly higher in the NERD group than in the control group (0.8 [0.7-1.1]). The salivary EGF concentration was significantly higher in the NERD group (2513.0 pg/mL [1497.5-5005.0] than in the PPI-responsive group (1641.0 [1139.8-2092.0], p = 0.0032).

CONCLUSION

Stimulated saliva secretion was reduced in PPI-responsive NERD patients.

Proteomic Characterization of Canine Gastric Fluid by Liquid Chromatography-Mass Spectrometry for Development of Protein Biomarkers in Regurgitation, Vomiting, and Cough

Reflux and aspiration in people cause and exacerbate respiratory diseases in the absence of gastrointestinal signs. Protein biomarkers in humans detect extraesophageal reflux (EER) from oropharyngeal (OP) and bronchoalveloar lavage samples. Reflux likely contributes to respiratory disease in dogs. The objectives of this study were to analyze the canine gastric fluid (GF) proteome and compare this to the OP proteome in normal, vomiting/regurgitating, and coughing dogs to identify biomarkers for EER/aspiration. Twenty-three client-owned dogs were enrolled. Canine GF samples (n = 5) and OP swabs in normal (n = 6), vomiting/regurgitating (n = 7), and coughing (n = 5) dogs were within 2 weeks of sample collection. Protein digests were analyzed by liquid chromatography–mass spectrometry. Differential abundance (DA) of proteins between groups was evaluated by Fisher's exact test with p < 0.0004 significance level after correction for multiple comparisons. DA was found between all groups (p < 0.0001): GF vs. normal (n = 130 proteins), coughing vs. normal (n = 22 proteins), and vomiting/regurgitating vs. normal (n = 20 proteins). Protein abundance was highly variable between dogs. Gastrointestinal-specific proteins were found in OP swabs from vomiting/regurgitating and coughing dogs but not from healthy dogs. In conclusion, the proteomic composition of the OP varies between health and disease. The presence of gastrointestinal-specific proteins in OP of coughing dogs may suggest reflux and/or aspiration as contributing factors. The variable protein abundance warrants investigation into biomarker panels.

Stimulated saliva secretion is reduced in proton pump inhibitor-resistant severe reflux esophagitis patients

BACKGROUND

Salivary secretion in patients with proton-pump inhibitor (PPI)-resistant severe reflux esophagitis has not been examined. In this study, saliva secretion and salivary epidermal growth factor (EGF) in patients with PPI-resistant severe reflux esophagitis were investigated.

METHODS

We recruited 22 PPI-resistant and 22 PPI-responsive severe reflux esophagitis patients who were not infected with Helicobacter pylori. Saliva secretion testing and esophageal manometry using high-resolution manometry were performed. Saliva secretion was assessed as follows: each patient chewed sugar-free gum for 3 min prior to endoscopy and the amount and pH of saliva as well as the pH of saliva after acid loading as an index of the acid-buffering capacity were measured. The salivary EGF concentration was assessed by ELISA.

RESULTS

The amount of saliva secreted was significantly lower in the PPI-resistant group than in the PPI-responsive group, with medians (25th-75th percentile) of 3.7 (2.2-6.8) and 4.9 (4.0-7.8) mL, respectively (p = 0.029). Salivary pH was significantly lower in the PPI-resistant group [6.9 (6.7-7.2)] than in the PPI-responsive group [7.2 (7.1-7.4), p = 0.001]. Salivary pH after acid loading was significantly lower in the PPI-resistant group [5.6 (5.3-5.9)] than in the PPI-responsive group [6.4 (6.1-6.5), p = 0.002]. The salivary EGF concentration was significantly higher in the PPI-resistant group [3211.5 (1865.0-4121.5)] than in the PPI-responsive group [1816.0 (1123.5-2792.3), p = 0.041]. No significant differences were observed in the proportion of esophageal motility abnormalities.

CONCLUSION

Stimulated saliva secretion was reduced in PPI-resistant severe reflux esophagitis patients.

The therapeutic importance of acid-base balance

Baking soda and vinegar have been used as home remedies for generations and today we are only a mouse-click away from claims that baking soda, lemon juice, and apple cider vinegar are miracles cures for everything from cancer to COVID-19. Despite these specious claims, the therapeutic value of controlling acid-base balance is indisputable and is the basis of Food and Drug Administration-approved treatments for constipation, epilepsy, metabolic acidosis, and peptic ulcers. In this narrative review, we present evidence in support of the current and potential therapeutic value of countering local and systemic acid-base imbalances, several of which do in fact involve the administration of baking soda (sodium bicarbonate). Furthermore, we discuss the side effects of pharmaceuticals on acid-base balance as well as the influence of acid-base status on the pharmacokinetic properties of drugs. Our review considers all major organ systems as well as information relevant to several clinical specialties such as anesthesiology, infectious disease, oncology, dentistry, and surgery.

NETs Are Double-Edged Swords with the Potential to Aggravate or Resolve Periodontal Inflammation

Periodontitis is a general term for diseases characterised by inflammatory destruction of tooth-supporting tissues, gradual destruction of the marginal periodontal ligament and resorption of alveolar bone. Early-onset periodontitis is due to disturbed neutrophil extracellular trap (NET) formation and clearance. Indeed, mutations that inactivate the cysteine proteases cathepsin C result in the massive periodontal damage seen in patients with deficient NET formation. In contrast, exaggerated NET formation due to polymorphonuclear neutrophil (PMN) hyper-responsiveness drives the pathology of late-onset periodontitis by damaging and ulcerating the gingival epithelium and retarding epithelial healing. Despite the gingival regeneration, periodontitis progression ends with almost complete loss of the periodontal ligament and subsequent tooth loss. Thus, NETs help to maintain periodontal health, and their dysregulation, either insufficiency or surplus, causes heavy periodontal pathology and edentulism.

The esophageal mucosal barrier in health and disease: mucosal pathophysiology and protective mechanisms

Diseases of the esophagus, such as gastroesophageal reflux (GER), can result in changes to mucosal integrity, neurological function, and the microbiome. Although poorly understood, both age and GER can lead to changes to the enteric nervous system. In addition, the esophagus has a distinct microbiome that can be altered in GER. Mucosal integrity is also at risk due to persistent damage from acid. Diagnostic tools, such as ambulatory pH/impedance testing and esophageal mucosal impedance, can assess short-term and longitudinal GER burden, which can also assess the risk for mucosal compromise. The quality of the mucosal barrier is determined by its intercellular spaces, tight junctions, and tight junction proteins, which are represented by claudins, occludins, and adhesion molecules. Fortunately, there are protective factors for mucosal integrity that are secreted by the esophageal submucosal mucous glands and within saliva that are augmented by mastication. These protective factors have potential as therapeutic targets for GER. In this article, we aim to review diagnostic tools used to predict mucosal integrity, aging, and microbiome changes to the esophagus and esophageal mucosal defense mechanisms.

Rebamipide using in gastroesophageal reflux disease treatment

Rebamipide is a mucoprotective drug which was developed in Japan in 1990. The therapeutic effect of rebamipide based on the induction of cyclooxygenase-2 and increasing level of prostaglandins, inhibition of oxygen free radicals production, epidermal growth factor stimulation, vascular endothelial growth factor, nitric oxide, and decreasing of lipid peroxidation and neutrophils migration. The combination of proton pump inhibitors and rebamipide is more effective in relieving of gastroesophageal reflux disease symptoms and reducing recurrence rate of disease. Using rebamipide in the treatment of gastroesophageal reflux disease is justified because this drug has a unique mechanism of action, which eliminating the main stages of pathogenesis of the disease.

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.

Does the healing of the esophageal mucosa improve the function of the esophageal submucosal and salivary glands?

The esophageal pre-epithelial barrier encompasses components of secretions from both the esophageal submucosal and salivary glands. We demonstrated, in patients with reflux esophagitis (RE), significantly diminished luminal release of esophageal epidermal growth factor (EGF). The rate of luminal release of esophageal prostaglandin E₂ (PGE₂ ) was significantly higher compared with controls and significantly declined after healing of RE. Patients with RE also exhibited significant declines in esophageal mucin secretion; however, after healing of RE with rabeprazole, this rate increased significantly. The rate of salivary EGF and bicarbonate secretion in patients with RE was significantly lower than in controls. We have demonstrated that mastication of tasteless parafilm, which could be substituted with sugarless chewing gum in the clinical scenario, resulted in profound and significant increases in the rate of secretion of salivary protective factors, such as bicarbonate, mucin, protein, EGF, and PGE₂ , in patients with RE. Our data clearly indicate that there is a relationship between the form or the structure of the esophageal mucosa and the secretory function of not only the esophageal submucosal glands but also the salivary glands. Application of masticatory stimulation in a clinical scenario may also have some therapeutic potential.

The esophageal microbiota in health and disease

The esophageal mucosa is among the sites colonized by human microbiota, the complex microbial ecosystem that colonizes various body surfaces and is increasingly recognized to play roles in several physiological and pathological processes. Our understanding of the composition of the esophageal microbiota in health and disease is challenged by the need for invasive sampling procedures and by the dynamic nature of the esophageal environment and remains limited in comparison with the information available for other body sites. Members of the genus Streptococcus appear to be the major components of the microbiota of the healthy esophagus, although the presence of several other taxa has also been reported. Dysbiosis, consisting of enrichment in some Gram-negative taxa (including Veillonella, Prevotella, Haemophilus, Neisseria, Campylobacter, and Fusobacterium), has been reported in association with gastroesophageal reflux disease and is hypothesized to contribute to the evolution of this condition toward Barrett's esophagus (which is the most common esophageal precancerous lesion) and, eventually, adenocarcinoma. Some Campylobacter species (mostly C. concisus) are also putatively involved in the progression of disease toward adenocarcinoma. However, variable findings have recently been reported in additional studies. Causative relationships between dysbiosis or specific bacterial species and esophageal diseases remain controversial and warrant further investigations.