Dilated intercellular spaces of esophageal epithelium in nonerosive reflux disease patients with physiological esophageal acid exposure

Acid modulates the squamous epithelial barrier function by modulating the localization of claudins in the superficial layers

Acid is a major cause of gastro-esophageal reflux disease. However, the influence of acid on the esophageal stratified epithelial barrier function and tight junction (TJ) proteins is not fully understood. Here, we explore the influence of acid on barrier function and TJ proteins using a newly developed model of the esophageal-like squamous epithelial cell layers that employs an air-liquid interface (ALI) system. Barrier function was determined by measuring trans-epithelial electrical resistance (TEER) and diffusion of paracellular tracers. TJ-related protein (claudin-1, claudin-4, occludin and ZO-1) expression and localization was examined by immunofluorescent staining, and by western blotting of 1% NP-40 soluble and insoluble fractions. We also examined the influence of acid (pH 2-4) on the barrier created by these cells. The in vitro ALI culture system showed a tight barrier (1500-2500 Ω·cm(2)) with the expression of claudin-1, claudin-4, occludin and ZO-1 in the superficial layers. Claudin-1, claudin-4, occludin and ZO-1 were detected as dots and whisker-like lines in the superficial layers, and as a broad line in the suprabasal layers. These localization patterns are similar to those in the human esophagus. On day 7 under ALI culture, TJ proteins were detected in the superficial layers with functional properties, including decreased permeability and increased TEER. Dilated intercellular spaces were detected at the suprabasal cell layers even under the control conditions of ALI cells. pH 2 acid on the apical side significantly reduced the TEER in ALI-cultured cells. This decrease in TEER by the acid was in parallel with the decreased amount of detergent-insoluble claudin-4. Claudin-4 delocalization was confirmed by immunofluorescent staining. In conclusion, TJs are located in the superficial layers of the esophagus, and acid stimulation disrupts barrier function, at least in part by modulating the amount and localization of claudin-4 in the superficial layers.

Is intercellular space different among layers in normal esophageal mucosa? An electron microscopic study

BACKGROUND/INTRODUCTION

Dilatation of intercellular space (IS) of esophageal epithelial cells is described as a sensitive early marker for epithelial damage by refluxate. Esophageal epithelia are morphologically subdivided into three layers according to the shape of the cells and nuclei. Meanwhile, ten transmission electron microscopy (TEM) photographs and ten randomly selected measurements per photo from gastroesophageal reflux disease (GERD) patients have been widely accepted without any theoretical criticism. We assumed that the IS differs among each layer and thus studied IS according to subdivided layers of normal esophageal epithelium. We also evaluated an optimal number of IS measurements per photograph.

MATERIALS AND METHODS

Esophagogastroduodenoscopy was performed in 15 healthy adults without any symptom of GERD, taking biopsies from mucosa above 5 cm from the squamo-columnar junction. Tissues were handled and prepared for TEM, verifying three layers of esophageal mucosa, i.e., squamous cell layer, prickle cell layer, and basal layer. Ten digital photomicrographs were taken from each three layers by TEM, and ISs were measured with a computerized image analysis program. For the method of measuring IS, 5, 10, 20, 30, and 40 measurements per photomicrograph were respectively performed by four different examiners. Mean value and intraclass correlation coefficient (ICC) was also yielded.

RESULTS

Mean IS of lower esophagus irrelevant to three epithelial layers were 0.39 ± 0.30 μm. When subdivided into three layers, however, mean IS of squamous cell layer was 0.62 ± 0.23 μm, prickle cell layer 0.23 ± 0.19 μm, and basal layer 0.55 ± 0.36 μm, with their difference statistically significant (p < 0.05). On the other hand, ICC of 5, 10, 20, 30, and 40 measurements were 0.688, 0.917, 0.837, 0.790, and 0.765, respectively.

CONCLUSIONS

Mean IS values of each three layers of esophageal epithelium in normal subjects were significantly different, and reconsideration of the standard measurement method is needed. Ten measurements per photo had an adequate inter-observer agreement.

Bioimpedance spectroscopy: a new tool to assess early esophageal changes linked to gastroesophageal reflux disease?

Bioimpedance spectroscopy can identify pathological changes related to precancerous lesions of the cervix uteri and esophagus. It therefore has the potential to detect early reflux-related changes in the esophageal mucosa, such as dilated intercellular spaces. The reliable detection of dilated intercellular spaces at the time of endoscopy would yield a significant diagnostic advantage for separating patients with functional heartburn from the large proportion of patients with gastroesophageal reflux symptoms but no macroscopic esophagitis or pathological acid exposure. The bioimpedance of the esophageal mucosa, measured with a small caliber probe, was evaluated in a series of preclinical experiments. First, sections of rabbit esophageal epithelium were mounted in Ussing chambers and exposed to solutions at pH 7.4 or pH 1.5 for 45 minutes. Impedance measurements were taken at varying probe pressures. Second, rabbit esophageal epithelia were perfused for 45 minutes in situ with pH 1.1 or control solutions and impedance measurements taken. Samples from both in vitro and in situ experiments were taken for morphological examination by light microscopy. Finally, esophageal bioimpedance was measured in awake dogs with permanent esophagocutaneous stoma. The in situ experiments demonstrated that morphological changes in the esophageal mucosa could be discerned by the use of bioimpedance spectroscopy. The variability in resistivity was species-independent but was affected by the pressure applied to the probe. The results suggest that evaluation of bioimpedance spectroscopy for use in a clinical setting is warranted. Small morphological differences in the esophageal mucosa may be detected by the use of bioimpedance spectroscopy.

Dilated intercellular spaces and lymphocytes on biopsy relate to symptoms in erosive GERD but not NERD

BACKGROUND

Mechanisms of symptom perception among patients with gastro-oesophageal reflux disease (GERD) remain to be fully elucidated.

AIM

To correlate quantitative reflux symptom scores with microscopic oesophageal histopathology.

METHODS

Prior to endoscopy, patients with reflux symptoms completed a validated reflux disease questionnaire (score 0-36). Erosive oesophagitis (EO) was graded using the LA classification. Oesophageal biopsies were graded 0-2 for basal cell hyperplasia, papillary elongation, dilated intercellular spaces (DIS), necrosis or erosion, eosinophils and neutrophils by a blinded gastrointestinal pathologist as previously described. Additionally, lymphocyte density was also evaluated. Pearson's correlation coefficients were computed.

RESULTS

Thirty-two EO and 21 non-erosive reflux disease (NERD) patients were prospectively enrolled. For EO vs. NERD, mean reflux symptom scores (10.7 vs. 8.8, P=0.35) and histology scores were similar (4.29 vs. 4.25; P=0.9). However, when symptom scores were compared with histology scores, a correlation was found in the EO group, but not in the NERD group (r=0.34, P=0.05 vs. r=0.22, P=0.36). On further analysis, DIS was associated with symptom scores in the EO group (P≤0.001), but not in the NERD group (P=N.S.). Similarly, lymphocyte density was associated with symptom scores in the EO group (r=0.56, P=0.0009), but not in the NERD group (r=0.002, P=0.9).

CONCLUSIONS

Although mean symptom and histology scores were similar in the EO and NERD groups, a significant correlation of symptom scores with histology scores, DIS and lymphocytes was found in the former, but not in the latter. EO and NERD patients may have different symptom perception mechanisms and thus, dissimilar symptom resolution rates with acid suppression.

Intercellular space volume is mainly increased in the basal layer of esophageal squamous epithelium in patients with GERD

BACKGROUND/AIMS

At present, the dilation of esophageal intercellular spaces (ICS) is considered an early morphologic marker of acid damage in patients with GERD. Nevertheless, previous electron microscopic (EM) studies had focused only on the suprabasal layer of squamous epithelium or did not nearly specify which layer of squamous epithelium was studied. Therefore, we aimed to assess the volumetric amount of the ICS in all layers of SE in patients with GERD.

METHODS

In this study, 48 patients were prospectively included (NERD = 18, ERD = 17; Barrett's esophagus = 5, controls = 8). All patients with ERD and NERD had typical reflux symptoms, as assessed by a valid GERD questionnaire. ICS volume was assessed by electron microscopy in the superficial, prickle cell, and basal layers of esophageal squamous epithelium using the method of Weibel.

RESULTS

ERD was associated with increased ICS volume in the basal layer (LA-A, p = 0.038; LA-B, p = 0.005) and prickle cell layer (LA-A, p = 0.006; LA-B, p = 0.007) as compared to controls. Comparisons between NERD and ERD patients revealed more dilated ICS in the basal layer (LA-B, p = 0.007), prickle cell layer (LA-A, p = 0.008; LA-B, p = 0.001) and superficial layer (LA-B, p = 0.018) in patients with ERD.

CONCLUSIONS

Not only the diameter but also the volume of the ICS is increased in patients with GERD. Furthermore, the dilation of ICS is present in all three layers of the SE, being more pronounced in the basal layer. These findings support the concept that the impairment of the esophagus begins in the deeper parts of the esophageal epithelium.

Refractory heartburn: comparison of intercellular space diameter in documented GERD vs. functional heartburn

OBJECTIVES

Refractory heartburn despite acid suppression may be explained by ongoing gastroesophageal reflux disease (GERD) or functional heartburn (FH), i.e., symptoms without evidence of GERD. Impedance-pH monitoring (impedance-pH) detects acid and nonacid reflux and is useful for evaluating acid-suppressed, refractory patients. Intercellular space diameter (ISD) of esophageal epithelium measured by transmission electron microscopy (TEM) is a marker of epithelial damage present in both erosive and nonerosive reflux disease. ISD has not been used to study refractory heartburn or FH. Our aim was to compare ISD in healthy controls and refractory heartburn patients with GERD and FH.

METHODS

In refractory heartburn patients (heartburn more than twice/week for at least 2 months despite proton pump inhibitor (PPI) b.i.d.), erosive esophagitis and/or abnormal impedance-pH (increased acid exposure or positive symptom index) defined GERD; normal esophagogastroduodenoscopy (EGD)/impedance-pH defined FH. Asymptomatic, healthy controls had normal EGD and pH-metry. Mean ISD in each subject, determined by blinded TEM of esophageal biopsies, was the average of 100 measurements (10 measurements in each of 10 micrographs).

RESULTS

In all, 11 healthy controls, 11 FH, and 15 GERD patients were studied. Mean ISD was significantly higher in GERD compared with controls (0.87 vs. 0.32 μm, P=0.003) and FH (0.87 vs. 0.42 μm, P=0.012). Mean ISD was similar in FH and controls (0.42 vs. 0.32 μm, P=0.1). The proportion of patients with abnormal ISD was significantly higher for GERD compared with FH (60 vs. 9%, P=0.014).

CONCLUSIONS

ISD is increased in refractory heartburn patients with GERD but not those with FH. Our findings suggest that measurement of ISD by TEM might be a useful tool to distinguish GERD from FH in patients with refractory heartburn.

Role of corticotrophin-releasing factor in the stress-induced dilation of esophageal intercellular spaces

Corticotrophin-releasing factor (CRF) plays a major role in coordinating stress responses. We aimed to test whether blocking endogenous CRF activity can prevent the stress-induced dilation of intercellular spaces in esophageal mucosa. Eighteen adult male rats were divided into 3 groups: 1) a non-stressed group (the non-stressed group), 2) a saline-pretreated stressed group (the stressed group), 3) and an astressin-pretreated stressed group (the astressin group). Immediately after completing the experiments according to the protocol, distal esophageal segments were obtained. Intercellular space diameters of esophageal mucosa were measured by transmission electron microscopy. Blood was sampled for the measurement of plasma cortisol levels. Mucosal intercellular spaces were significantly greater in the stressed group than in the non-stressed group. Mucosal intercellular spaces of the astressin group were significantly smaller than those of the stressed group. Plasma cortisol levels in the stressed group were significantly higher than in the non-stressed group. Pretreatment with astressin tended to decrease plasma cortisol levels. Acute stress in rats enlarges esophageal intercellular spaces, and this stress-induced alteration appears to be mediated by CRF. Our results suggest that CRF may play a role in the pathophysiology of reflux-induced symptoms or mucosal damage.

Esophageal Intraepithelial Neutrophil Infiltration is Common in Nigerian Patients With Non-Erosive Reflux Disease

Background

Non-erosive reflux disease (NERD) is a variant of gastroesophageal reflux disease (GERD) in which patients with typical reflux symptoms have no evidence of erosive esophagitis at endoscopy. An objective diagnostic tool for NERD remains an unmet need for clinicians and researchers. This study was designed to determine the types of histological alterations seen in Nigerian patients with NERD.

Methods

This was a prospective cross-sectional study in which mucosal biopsy was taken from the lower esophagus in patients with NERD. Similar biopsy was also taken from patients with nonulcer dyspepsia who served as controls. The materials were processed and examined histologically.

Results

There were 68 patients with NERD and 60 patients with nonulcer dyspepsia. Intraepithelial neutrophil infiltration was significantly more frequent in patients with NERD compared to those with nonulcer dyspepsia (47.1% vs 13.3%, P = 0.0326). Epithelial proliferative chnges in the form of basal cell hyperplasia and papilla elongation were minimal (11.8% and 3.3% respectively).

Conclusions

Nigerian patients with NERD have a high degree of esophageal intraepithelial neutrophil infiltration and a low prevalence of epithelial proliferative changes. This may be related to the relative rarity of Barrett’s esophagus in Nigerians.

The hypersensitive esophagus: pathophysiology, evaluation, and treatment options

Visceral hypersensitivity plays a key role in the pathogenesis of esophageal functional disorders such as functional heartburn and chest pain of presumed esophageal origin (noncardiac chest pain). About 80% of patients with unexplained noncardiac chest pain exhibit lower esophageal sensory thresholds when compared to controls during esophageal sensory testing (ie, esophageal barostat, impedance planimetry). Such information has led to prescription of peripherally and/or centrally acting therapies for the management of these patients. This review summarizes and highlights recent and significant findings regarding the pathophysiology, evaluation, and treatment of the hypersensitive esophagus, a central factor in functional esophageal disorders.

The feasibility of light microscopic measurements of intercellular spaces in squamous epithelium in the lower-esophagus of GERD patients

The study aims to determine whether light microscopy can be used to accurately measure the diameters of intercellular spaces between squamous epithelial cells in the lower esophagus, and whether changes in this outcome measure can be used as a diagnostic marker for gastroesophageal reflux disease (GERD). The study has two parts. Part 1 involves 42 asymptomatic controls and 119 patients with typical symptoms of GERD, including 58 with erosive esophagitis (EE), and 61 patients with nonerosive gastroesophageal reflux disease (NERD). All biopsies were taken from the lower esophagus. All samples were observed using an immersion objective, after which diameters were measured by computer-assisted morphometry. Part 2 involves 61 individuals who were randomly selected from part 1, including 19 controls, 13 with NERD and 29 with EE. Diameter measurements using both light microscopy and transmission electron microscopy (TEM) were performed for samples of 61 individuals. Samples from a total of 61 individuals (31 male, 30 female, mean age 44.3 ± 16.0 years) were observed using both light microscopy and TEM. Both methods showed significant differences between control and disease groups; the outcomes from the two methods had a certain correlation (r = 0.605, P = 0.000). Morphometric analysis of all 161 individuals (83 males, 78 females, mean age 41.4 ± 15.7) showed mean diameters from light microscopy to be 0.58 ± 0.16 µm for controls, 1.07 ± 0.30 µm for NERD, and 1.29 ± 0.20 µm for EE; differences between control and disease groups were significant (P<0.05). The optimal cut-off value from receiver operator characteristic analysis was 0.85 µm. Diagnoses were validated using the combination of symptoms of GERD, endoscopy, and 24 h ambulatory pH monitoring as the gold standard. At the optimal cutoff, sensitivity was 93.3% and specificity was 100%. The diameters of the intercellular spaces in squamous epithelium of lower esophagus from controls and in patients with GERD can be quantitatively measured using light microscopy. Dilated diameters can serve as a sensitive, specific, and objective indicator for diagnosis of GERD.

Perception of gastro-oesophageal reflux

Gastro-oesophageal reflux disease (GORD) is common and often associated with unpleasant symptoms requiring utilisation of health care resource. While in the majority of patients symptom resolution occurs with acid suppressant therapy, in a proportion this treatment is ineffective in resolving symptoms. This is particularly the case in patients with non-erosive reflux disease (NERD) and functional heartburn (FH). It is increasingly being recognised that the presence of acid in the oesophagus can cause dilated intercellular spaces (DIS) which increases the exposure of the sub-epithelial nerves to the acid. Experimental studies in both animals and humans suggest that a variety of receptors on afferent nerves can be sensitised upon exposure to acid so that there is increased afferent input to the spinal cord dorsal horn neurons which leads to a reduction in threshold of these neurons together with an increase in their receptive field. This increased sensitivity of primary afferent nerves is described as peripheral sensitisation, whereas the consequent increase in sensitivity of the spinal dorsal horn neurons is described as central sensitisation. Once these mechanisms have been established they can cause a long term increase in sensitivity of tissues to previously innocuous stimuli. Furthermore, psychological stress has been shown to increase DIS and may therefore facilitate peripheral sensitisation. Currently peripheral and central sensitisations are considered to be important mechanisms of oesophageal pain hypersensitivity and occurrence of symptoms to even physiological amounts of acid. In these patients treatments aimed at reducing neuronal sensitivity may be effective in the management.

Medical treatment of GORD. Emerging therapeutic targets and concepts

Approximately 20-30% of patients with gastro-oesophageal reflux symptoms report inadequate symptom relief while on PPI therapy. Persisting acid or non-acid reflux can be demonstrated in 40-50% of them suggesting that there is room for anti-reflux therapy in these patients. New anti-reflux compounds aim at decreasing the occurrence of transient lower oesophageal sphincter relaxations (TLOSRs) which represent the main mechanism of all types of reflux. The most promising classes of compounds are GABA(B) agonists and mGluR5 antagonists which have been shown to reduce both reflux episodes and symptoms and are currently under evaluation in phase II and III clinical trials. Compounds that target TLOSR activity represent a promising new therapeutic option for patients who suffer from GORD symptoms. These drugs will probably be developed as add-on therapy in combination with PPIs provided the tolerability and safety issues are resolved.

The integrity of the esophageal mucosa. Balance between offensive and defensive mechanisms

Heartburn is the most common and characteristic symptom of gastroesophageal reflux disease. It ultimately results from contact of refluxed gastric acid with nociceptors within the esophageal mucosa and transmission of this peripheral signal to the central nervous system for cognition. Healthy esophageal epithelium provides an effective barrier between refluxed gastric acid and esophageal nociceptors; but this barrier is vulnerable to attack and damage, particularly by acidic gastric contents. How gastric acid is countered by defensive elements within the esophageal mucosa is a major focus of this discussion. When the defense is successful, the subject is asymptomatic and when unsuccessful, the subject experiences heartburn. Those with heartburn commonly fall into one of three endoscopic types: nonerosive reflux disease, erosive esophagitis and Barrett's esophagus. Although what determines endoscopic type remains unknown; it is proposed herein that inflammation plays a key, modulating role.

Dilated intercellular spaces and chronic cough as an extra-oesophageal manifestation of gastrooesophageal reflux disease

Chronic cough is one of the extra-oesophageal manifestations of gastrooesophageal reflux disease (GORD). It is presumed to occur either directly by microaspiration of acidic gastric contents into the airway or indirectly by a reflex triggered by contact of acidic refluxates with the oesophageal epithelium in GORD. How contact of the oesophageal epithelium with acidic refluxates promotes sensitization for chronic cough is unknown, but like heartburn, which is a necessary accompaniment, it requires acid activation of nociceptors within the oesophageal mucosa. Dilated intercellular spaces within the oesophageal epithelium, a reflection of an increase in paracellular permeability, is a histopathologic feature of both erosive and non-erosive forms of GORD. Since it correlates with the symptom of heartburn, it is hypothesized herein that the increase in paracellular permeability to acid reflected by dilated intercellular spaces in oesophageal epithelium also serves as mediator of the signals that produce the reflex-induced sensitization for cough--a sensitization that can occur centrally within the medullary Nucleus Tractus Solitarius or peripherally within the tracheobronchial tree.

Dilated intercellular space in chronic laryngitis and gastro-oesophageal reflux disease: at baseline and post-lansoprazole therapy

BACKGROUND

Dilation of intercellular spaces is reported to be an early morphological marker in gastro-oesophageal reflux. It remains unknown if this marker is useful in diagnosing reflux-related chronic laryngitis.

AIM

To determine histopathology and electron microscopic changes in oesophageal and laryngeal epithelium in chronic laryngitis.

METHODS

In this prospective blinded study, we enrolled 53 participants: 15 controls, 20 patients with GERD and 18 patients with chronic laryngitis. The latter two groups were subsequently treated with lansoprazole 30 mg bid for 12-weeks. Baseline and postacid suppressive therapy biopsies were obtained from distal oesophagus and laryngeal postcricoid areas. Biopsy specimens were evaluated for histopathology and dilated intercellular space changes.

RESULTS

There was no significant increase in oesophageal or laryngeal epithelium intercellular spaces among GERD or laryngitis patients compared with controls at baseline or postacid suppressive therapy. Only patients with GERD had significantly (P = 0.03) higher proportion of moderate-to-severe oesophageal spongiosis and basal cell hyperplasia, which normalized postacid suppressive therapy.

CONCLUSIONS

There was no increase in the width of intercellular spaces in the oesophagus or larynx in GERD or chronic laryngitis at baseline or postacid suppressive therapy. Our findings question the uniform presence of dilated intercellular space in patients with GERD.

Management of gastroesophageal reflux disease that does not respond well to proton pump inhibitors

PURPOSE OF REVIEW

Patients with gastroesophageal reflux disease (GERD) who are not responding to proton pump inhibitors (PPIs) given once daily are very common. These therapy-resistant patients have become the new face of GERD in clinical practice in the last decade and presently pose a significant therapeutic challenge to the practicing physician. We reviewed newly accumulated information about the management of PPI failure that has been published over the past 2 years.

RECENT FINDINGS

There are diverse mechanisms that contribute to the failure of PPI treatment in GERD patients and they are not limited to residual reflux. Some of the causes of PPI failure may coincide in the same patient. Upper endoscopy appears to have limited diagnostic value. In contrast, esophageal impedance with pH testing on therapy appears to provide the most insightful information about the subsequent management of these patients. Commonly, doubling the PPI dose or switching to another PPI will be offered to patients who failed PPI once daily. Failure of such therapeutic strategies is commonly followed by assessment for residual reflux. There is growing information about the potential value of compounds that can reduce transient lower esophageal sphincter relaxations. Esophageal pain modulators are commonly offered to patients with functional heartburn, although supportive clinical studies are still missing.

SUMMARY

Management of refractory GERD patients remains an important clinical challenge. Recent studies have cemented the value of impedance-pH testing in pursuing proper treatment. Presently, the most promising therapeutic development for this patient population is transient lower esophageal sphincter relaxation reducers.

Increased TRPV1 gene expression in esophageal mucosa of patients with non-erosive and erosive reflux disease

BACKGROUND

Transient receptor potential channel vanilloid subfamily member-1 (TRPV1) may play a role in esophageal perception. TRPV1 mRNA and protein expression were examined in the esophageal mucosa of non-erosive reflux disease (NERD) and erosive esophagitis (EE) patients and correlated to esophageal acid exposure.

METHODS

Seventeen NERD patients, eight EE patients and 10 healthy subjects underwent endoscopy after a 3-week washout from proton pump inhibitors or H2 antagonists. Biopsies, obtained from the distal esophagus, were used for conventional histology, for Western blot analysis and/or quantitative real-time polymerase chain reaction (qPCR). Overall 13 NERD patients, four EE patients and five controls underwent ambulatory pH-testing.

KEY RESULTS

TRPV1 expression was increased in all NERD and EE patients, as measured by Western blot analysis (0.65 +/- 0.07 and 0.8 +/- 0.05 VS 0.34 +/- 0.04 in controls; P < 0.01) and by qPCR (1.98 +/- 0.21 and 2.52 +/- 0.46 VS 1.00 +/- 0.06; P < 0.01). Neutrophilic infiltration, in the mucosa, was detected only in EE patients.

CONCLUSIONS & INFERENCES

Non-erosive reflux disease and EE patients presented increased TRPV1 receptors mRNA and protein, although no correlation with acid exposure was demonstrated. Increased TRPV1 in the esophageal mucosa may contribute to symptoms both in NERD and EE patients and possibly account for peripheral mechanisms responsible for esophageal hypersensitivity in NERD patients.

Rikkunshito, a traditional Japanese medicine, may relieve abdominal symptoms in rats with experimental esophagitis by improving the barrier function of epithelial cells in esophageal mucosa

BACKGROUND

A traditional Japanese medicine, rikkunshito, has been reported to relieve dyspepsia symptoms. We investigated the effect of rikkunshito on RE-induced abdominal dyspepsia, and performed experiments to elucidate the mechanism of that effect.

METHODS

RE model rats were prepared using 8-week-old male Wistar rats, and rikkunshito was administered in drinking water. Voluntary movement was used as an index of RE-induced abdominal dyspepsia, which was monitored by an infrared sensor. On the tenth day after surgery, the total area of esophageal erosion was measured, and samples of nonerosive mucosa were collected. Using those samples, intercellular spaces of epithelial mucosa were examined by transmission electron microscopy, and the NP-40-soluble and -insoluble levels of the tight junction proteins claudin-1, -3 and -4 and their mRNAs were determined.

RESULTS

Rikkunshito did not reduce the average total area of erosive lesions in the esophageal mucosa of RE model rats. On day 10, voluntary movement was significantly decreased in the RE model rats and rikkunshito significantly increased it. Nonerosive esophageal mucosa from RE rats showed dilation of intercellular spaces in epithelium, and significantly decreased claudin-3 mRNA and protein levels. Rikkunshito significantly suppressed intercellular space dilation and significantly increased the level of NP-40-insoluble claudin-3, but it did not affect the mRNA level, suggesting that it promoted tight junction formation by facilitating the translocation of proteins.

CONCLUSION

Rikkunshito increased voluntary movement in RE model rats. This may have been because rikkunshito ameliorated the symptoms of RE by improving the barrier function of esophageal mucosa.

NK-1 receptor is involved in the decreased movement in a rat chronic acid reflux oesophagitis model

BACKGROUND

We previously reported that rats with reflux oesophagitis (RE) show a decrease in voluntary movement, which could be used as a measure of chronic visceral symptoms. However, what mediates these symptoms is still unknown, and pain-related neuropeptides or their receptors in oesophageal mucosa are possibly related to the symptom generation of oesophagitis. In the present study, we investigated the role of NK-1 receptor (NK-1R) as a mediator of oesophagitis symptoms.

METHODS

Chronic RE was surgically induced using rats. The degree or severity of oesophageal symptoms was evaluated by assessing voluntary movement, which was monitored using an infrared sensor system. The NK-1R antagonist, L-732,138, was administered and changes in voluntary movement were assessed. Ten days after surgery, the rats were killed to examine the oesophagus. NK-1R and tachykinin-1 mRNA were detected by real-time RT-PCR. NK-1R protein expression was examined by Western blotting.

KEY RESULTS

Voluntary movement of the oesophagitis model rats was significantly lower than that of the sham-operated rats on day 10. The size of oesophageal mucosal erosion did not correlate with the amount of voluntary movement. The amount of NK-1R protein and mRNA in the oesophageal tissue was significantly higher at both the erosion and non-erosion sites. The amount of tachykinin-1 mRNA in oesophageal tissue at the non-erosion sites was significantly higher in oesophagitis rats. The voluntary movement of oesophagitis rats was significantly increased by the administration of L-732,138.

CONCLUSIONS & INFERENCES

The NK-1R and related neuropeptides are possibly involved in the decrease in voluntary movement of RE.

Factors influencing intercellular spaces in the rat esophageal epithelium

AIM: To evaluate the effect of acute stress, hydrochloric acid, ethanol, aspirin, and prednisolone on the intercellular spaces of the esophageal epithelium.

METHODS: Part I, male Sprague-Dawley rats were randomly divided into eight groups and treated with the damaging or control factors. The esophagus of each rat was macroscopically inspected. Histological changes in mucosal biopsies were examined by light microscopy, and the widths of intercellular spaces were determined by transmission electron microscopy (TEM). Part II, in part I, we found that acute stress and aspirin induced dilated intercellular spaces (DIS) of the esophageal epithelium. Therefore, the effect of acid suppression pretreatment with esomeprazole on esophageal epithelial DIS induced by water immersion and restraint stress (WRS) and aspirin was further investigated to determine the association of DIS with acid reflux. After administration of 0.9% sodium chloride solution or esomeprazole solution orally for five days, rats underwent WRS or intragastric administration of aspirin solution. Esophageal epithelial intercellular spaces were investigated by TEM.

RESULTS: (1) The five damaging factors produced no lesions or inflammation in esophageal mucosa of rats under either gross or routine histological inspections. Esophageal epithelial intercellular space diameters in stress and aspirin groups were significantly greater, nearly three or two-fold respectively, than those in their corresponding control groups (stress model: 0.38 ± 0.05 μm vs 0.13 ± 0.02 μm, P < 0.01; aspirin model: 0.32 ± 0.12 μm vs 0.19 ± 0.05 μm, P < 0.01). Neither intragastric administration of hydrochloric acid or ethanol, nor hypodermic injection of prednisolone produced DIS compared with their corresponding control groups (hydrochloric acid model: 0.24 ± 0.03 μm vs 0.19 ± 0.05 μm, P > 0.05; ethanol model: 0.25 ± 0.10 μm vs 0.19 ± 0.05 μm, P > 0.05; prednisolone model: 0.20 ± 0.03 μm vs 0.14 ± 0.03 μm, P > 0.05); and (2) No significant difference in the intercellular space diameters was observed between the group pretreated with esomeprazole and the control group, in both the stress and aspirin models (stress model: 0.35 ± 0.05 μm vs 0.37 ± 0.05 μm, P > 0.05; aspirin model: 0.24 ± 0.02 μm vs 0.27 ± 0.03 μm, P > 0.05).

CONCLUSION: Acute stress and aspirin can induce DIS of the esophageal epithelium in rats, and it is not correlated with acid reflux.

Reactive nitrogen oxide species induce dilatation of the intercellular space of rat esophagus

OBJECTIVE

Dilatation of the intercellular space (DIS) of the esophageal epithelium is recognized as one of the earliest histological changes in gastroesophageal reflux disease patients. At the human gastroesophageal junction, reactive nitrogen oxide species (RNOS) are generated luminally through the entero-salivary re-circulation of dietary nitrate. In cases with gastroesophageal reflux, the site of luminal RNOS generation may shift to the distal esophagus. The aim of this study was to investigate whether luminal RNOS exposure could be involved in the pathogenesis of DIS.

MATERIAL AND METHODS

Rat esophageal mucosa was studied with an Ussing chamber model. On the luminal side of the chamber, RNOS were generated by the acidification of physiologic concentrations of sodium nitrite (1.0 or 5.0 mM). Esophageal barrier function was assessed by means of electrophysiological transmembrane resistance and membrane permeability by means of (3)H-mannitol flux. The dimensions of the intercellular spaces were assessed by using transmission electron microscopy.

RESULTS

Administration of acid plus sodium nitrite induced DIS of the esophageal epithelium, and this ultrastructural morphological change was accompanied by a concomitant decrease in the transmembrane resistance and an increase in the epithelial permeability. The DIS induced by luminal RNOS was also confirmed in an in vivo exposure model.

CONCLUSIONS

The present animal study indicates that the RNOS generated by the acidification of salivary nitrite in the presence of refluxed gastric acid in the esophagus could be a luminal factor that is responsible for the induction of DIS. Further studies are warranted to investigate the clinical relevance of the present findings to the human situation.

Review article: sleep-related gastro-oesophageal reflux as a distinct clinical entity

BACKGROUND

Many patients with chronic gastro-oesophageal reflux disease (GERD) have frequent nighttime heartburn as well as sleep-related gastro-oesophageal reflux (GOR). Sleep-related GOR has been shown to play an important role in the development of oesophagitis and other complications of GOR.

AIM

To present a conceptual argument that nighttime heartburn and associated sleep-related GOR should be recognized as a distinct clinical entity deserving special attention with regard to the diagnosis and treatment of GERD.

METHODS

The data presented come from surveys of GERD patients as well as from physiological studies to include studies monitoring oesophageal pH and spontaneous reflux events during polysomnographically (PSG) monitored sleep.

RESULTS

Evidence is presented to show that nighttime heartburn is prevalent and its occurrence separates patients from those who have heartburn most exclusively in the daytime. The evidence presented also supports the notion that nighttime heartburn sufferers have a more complicated disease and they have a greater risk of developing oesophagitis and other respiratory complications. The data also show that responses to acid mucosal contact are quite different during sleep compared to responses measured during the waking state.

CONCLUSIONS

Nighttime heartburn and GOR represent a distinct clinical entity which deserves specific attention in the diagnosis and optimal treatment of GERD.

The future of endoscopic esophageal therapy--what comes next

The diagnosis and treatment of esophageal diseases have undergone major changes over the last several years, and these are expected to continue. This article highlights these changes.

Oesophageal acid hypersensitivity is not a contraindication to Nissen fundoplication

BACKGROUND

The Rome III criteria classify patients with a positive relationship between symptoms and reflux episodes but a physiological oesophageal acid exposure time as having gastro-oesophageal reflux disease (GORD) with an acid hypersensitive oesophagus. The long-term outcome of antireflux surgery in these patients was investigated.

METHODS

Outcomes of Nissen fundoplication in 28 patients with GORD refractory to proton-pump inhibitors (PPIs) and oesophageal acid hypersensitivity (group 1) were compared with those of 126 patients with pathological acid exposure (group 2).

RESULTS

Fundoplication had a similar effect in both groups. Three months after surgery, total acid exposure time and the prevalence of oesophagitis had decreased, whereas mean lower oesophageal pressure had increased. The percentage of patients using PPIs was reduced from 83 to 4 per cent in group 1 and from 86.1 to 7.4 per cent in group 2 (both P < 0.001). Quality of life measured on a scale from 0 to 100 improved from 52 to 69 (P = 0.009) and 64 (P < 0.001) respectively. The percentage of patients with resolved or improved symptoms at 5 years was similar.

CONCLUSION

Patients with oesophageal acid hypersensitivity benefit from Nissen fundoplication as much as those with pathological acid exposure.

Dilated intercellular spaces as a marker of GERD

Gastroesophageal reflux disease (GERD) is typically heralded by the substernal burning pain of heartburn. On endoscopic examination, about one third of GERD subjects with heartburn have erosive disease, and the remainder have nonerosive reflux disease (NERD). Unlike patients with erosive disease, those with NERD (approximately 50%) often do not respond to therapy with proton pump inhibitors (PPIs), raising the question of whether they have NERD and, if they do, whether the cause of their symptoms is similar to those who respond to PPIs. Recently, biopsies established that subjects with heartburn and PPI-responsive NERD, like those with erosive esophagitis, have lesions within the esophageal epithelium known as dilated intercellular space (DIS). In this article, we discuss the physicochemical basis for DIS in acid-injured esophageal epithelium and its significance in GERD. Although DIS is not pathognomic of GERD, it is a marker of a break in the epithelial (junctional) barrier reflecting an increase in paracellular permeability.

Epidemiologic investigation of gastroesophageal reflux disease in the population of Anshun in Guizhou Province

AIM: To investigate the prevalence of gastroesophageal reflux disease (GERD) in the population of Anshun in Guizhou Province.

METHODS: From July 2006 to December 2006, a face-to-face interview was carried out in a randomly sampled population of Anshun in Guizhou Province using a validated Chinese version of Reflux Disease Questionnaire (RDQ) to assess the prevalence of GERD. The SPSS14.0 software package was used to perform the Chi-square test and t test.

RESULTS: A total of 1692 residents (836 males and 856 females) were investigated. The response rate was 96.2%. The responders ranged in age from 10 to 87 years, with a mean age of 42.2 ± 15.3 years. The prevalence of GERD in the population of Anshun in Guizhou Province was 6.9% according to the definition (RDQ score ≥ 12). The prevalence of GERD in male was higher than that in female though no significant difference was found (P > 0.05). The prevalence of GERD rose with age (P < 0.05).

CONCLUSION: The prevalence of GERD in the population of Anshun in Guizhou Province was higher than those reported in the populations of Guangdong Province, Beijing and Shanghai.

Laryngopharyngeal Reflux with Sore Throat: An Ultrastructural Study of Oropharyngeal Epithelium

Objectives:

We performed an electron microscopic ultrastructural study of oropharyngeal epithelium in patients with laryngopharyngeal reflux (LPR) and sore throat to evaluate whether dilatation of intercellular spaces could be traced at this level.

Methods:

The study included 20 patients with LPR and sore throat and 5 control subjects. The patients were subjected to upper gastrointestinal tract endoscopy and flexible pharyngolaryngoscopy. Oropharyngeal biopsy specimens were taken from the patients and controls for ultrastructural study by transmission electron microscopy.

Results:

The entire group of patients with LPR showed dilatation of intercellular spaces essentially at the squamous basal and suprabasal levels in their oropharyngeal biopsy specimens, whereas none of the control subjects showed such a morphological marker.

Conclusions:

Dilatation of intercellular spaces as a morphological marker can be traced in patients with LPR and sore throat at the level of the oropharynx. This contributes to a better understanding of the pathophysiology of LPR. If this finding is confirmed in a large series, it will represent a cost-effective, relatively noninvasive method for diagnosis of LPR.

A global, evidence-based consensus on the definition of gastroesophageal reflux disease in the pediatric population

OBJECTIVES

To develop an international consensus on the definition of gastroesophageal reflux disease (GERD) in the pediatric population.

METHODS

Using the Delphi process, a set of statements was developed and voted on by an international panel of eight pediatric gastroenterologists. Statements were based on systematic literature searches using Medline, EMBASE, and CINAHL. Voting was conducted using a six-point scale, with consensus defined, a priori, as agreed by 75% of the group. The strength of each statement was assessed using the GRADE system.

RESULTS

There were four rounds of voting. In the final vote, consensus was reached on 98% of the 59 statements. In this vote, 95% of the statements were accepted by seven of eight voters. Consensus items of particular note were: (i) GERD is present when reflux of gastric contents causes troublesome symptoms and/or complications, but this definition is complicated by unreliable reporting of symptoms in children under the age of approximately 8 years; (ii) histology has limited use in establishing or excluding a diagnosis of GERD; its primary role is to exclude other conditions; (iii) Barrett's esophagus should be defined as esophageal metaplasia that is intestinal metaplasia positive or negative; and (iv) extraesophageal conditions may be associated with GERD, but for most of these conditions causality remains to be established.

CONCLUSIONS

The consensus statements that comprise the Definition of GERD in the Pediatric Population were developed through a rigorous process. These statements are intended to be used for the development of future clinical practice guidelines and as a basis for clinical trials.

The Italian validation of the Montreal Global definition and classification of gastroesophageal reflux disease

BACKGROUND AND AIMS

Recently, a Global definition and a classification of gastroesophageal reflux disease (GERD) were developed by Montreal Consensus Group, composed of international expert gastroenterologists. Guidelines and consensus documents are, however, infrequently accepted and adopted at a local level. The aim of this study was to measure the acceptance of Montreal Global definition of GERD consensus document by specialists in a single country (Italy) and to measure the linguistic, scientific, and practical differences between the international consensus document and the Italian version.

METHODS

A 2-day meeting was held in June 2007 in Rome, Italy, attended by 147 Italian physicians who were experts in gastroenterology. They reviewed the individual original statements in their Italian translation and then voted on the statement using the scoring system used by the Montreal Consensus Group (6-point Likert scale). Voting was performed at baseline and after an analytical discussion on each statement, led by six internationally renowned experts. Consensus was defined as an agreement with a statement by at least two-thirds of the group. Results were compared with the Montreal statements.

RESULTS AND DISCUSSION

The level of consensus was already extremely high at the first vote (>90% with the two-thirds threshold). The level of agreement at the second vote increased slightly. The maximum variation between two votes was 33% (of increase from first to second round, 59-92%). The high level of agreement could be because of both the general acceptance of Montreal Consensus by scientific community, and the new scientific evidences published after the Montreal report, which fit with the original statements.

CONCLUSION

This study is the first national linguistic validation of the Montreal Global definition of GERD and is also proof of its scientific validity, based on the same methodology used to create the Montreal statements. It also suggests that evidence-based International disease classification systems can be applied to local settings after validation by local experts.

Experimental oesophagitis in the rat is associated with decreased voluntary movement

Growing interest has arisen regarding the mechanism of dyspeptic symptom generation. However, no evaluation system of these symptoms in animals has been developed. In this study, we examined whether voluntary movement of rats could be a measure to assess visceral symptoms of reflux oesophagitis. A chronic acid reflux oesophagitis model was made using rats, and the size of erosions was measured. Omeprazole was administered to the oesophagitis rats for 10 days. The amount of voluntary movement was measured by an infrared sensor. Intracellular spaces in oesophageal epithelium were also measured using a emission electron microscope. NP-40 soluble and insoluble fractions of claudins were examined by Western blot. Voluntary movement was significantly lower in the oesophagitis model rats than in the sham-operated rats (P < 0.01). Although omeprazole reduced the size of erosions, it did not significantly affect the total amount of voluntary movement (r = -0.033, P = 0.916). Intracellular spaces were significantly dilated in the oesophagitis model rats and claudin-3 showed a significantly lower relative quantity in the NP-40 insoluble fraction. Omeprazole significantly increased voluntary movement of oesophagitis model rats and the relative quantity of claudin-3 in the insoluble fraction (P < 0.05). Dilated intercellular spaces and the lower level of claudin-3 may relate to the voluntary movement of oesophagitis model rats. Decreases in voluntary movement of oesophagitis model rats may reflect visceral symptoms and be able to serve as an index of chronic abdominal symptoms.

Functional heartburn: what it is and how to treat it

Functional heartburn is considered one of the most common functional esophageal disorders. The disorder is more common in young women and is associated with other functional bowel disorders and psychological co-morbidity, primarily somatization. The etiology of functional heartburn remains unknown. Most patients, however, demonstrate esophageal hypersensitivity. Functional heartburn has been identified as the main cause for proton pump inhibitor (PPI) failure in patients with heartburn. Treatment is still a challenge, and patients should be started with PPI treatment. In non-responders, escalation of the PPI dose could be attempted and, if unsuccessful, pain modulators should be prescribed.

Intercellular space diameters of the oesophageal epithelium in NERD patients: head to head comparison between light and electron microscopy analysis

BACKGROUND

Dilation of intercellular space diameters of oesophageal epithelium detected at transmission electron microscopy morphometry is a marker of tissue injury in non-erosive reflux disease patients. Semi-quantitative evaluation of intercellular space diameters using light microscopy seems to provide promising results.

AIM/METHODS

To comparatively evaluate intercellular space diameters in the same patients, by means of morphometry and semi-quantitative analysis, both on light microscopy and transmission electron microscopy microphotographs, biopsies were taken in 29 non-erosive reflux disease patients at distal and proximal oesophagus. Twelve asymptomatic controls underwent the same protocol.

RESULTS

Morphometric analysis on transmission electron microscopy microphotographs showed mean intercellular space diameter values of patients, at distal and proximal oesophagus, 3- and 2-fold, respectively, higher than those in controls (p<0.001). On light microscopy microphotographs, mean intercellular space diameter values of patients at distal oesophagus were higher than those in controls, an overlap between patients and controls being observed. The semi-quantitative score was positive in 79% of patients and in 25% of controls at distal esophagus.

CONCLUSIONS

Intercellular space diameter morphometric analysis at light microscopy is widely available, allows intercellular space diameter to be quantitatively measured with good sensitivity and specificity and could represent a useful tool in non-erosive reflux disease diagnosis. Despite satisfactory sensitivity, the semi-quantitative score at light microscopy is hampered by much lower specificity than transmission electron microscopy- and light microscopy-morphometry.

Microscopic esophagitis in gastro-esophageal reflux disease: individual lesions, biopsy sampling, and clinical correlations

Patients with non-erosive reflux disease may show microscopic damage. This study is aimed to describe distribution, sensitivity, and specificity of histological lesions (i.e., basal cell hyperplasia-BH, papillae elongation-PE, dilatation of intercellular spaces-DIS, intraepithelial eosinophils-IE, neutrophils, and erosions) and sampling criteria. Four groups were identified on the basis of symptoms, endoscopy, and pH monitoring: (1) erosive esophagitis (n = 48), (2) non-erosive esophagitis with abnormal pH (n = 59), (3) non-erosive esophagitis with normal pH (n = 12), and (4) controls (n = 20). Biopsies were taken at the Z-line and 2 and 4 cm above it. BH, PE, DIS, IE, neutrophils, and erosions were assessed. A global severity score was calculated on the basis of the above parameters and allowed the distinction of patients from controls with 80% sensitivity and 85% specificity. Lesions were more severe at Z-line than proximally and more expressed in erosive than in non-erosive disease, although more than 70% of latter patients still showed histological damage. Esophageal biopsy seems very attractive in non-erosive disease where it may contribute to diagnosis and play a role in the comparative evaluation of different therapies.

Medical management of gastroesophageal reflux disease

Antisecretory therapies that raise intragastric pH provide the best healing of the esophageal mucosal damage that occurs in gastroesophageal reflux disease. Continuous maintenance therapy is also effective to reduce the likelihood of recurrence of esophagitis and control symptoms in the long term. Proton pump inhibitor (PPI) therapy is an effective approach for healing esophagitis and controlling symptoms. Endoscopic and surgical treatments may provide an option for patients who are refractory to PPIs in whom reflux has been clearly demonstrated. Long-term antireflux medication is often needed after surgical treatment because of persisting or recurrent pathologic reflux and symptoms. An alternative approach to controlling transient lower esophageal sphincter relaxations, such as the GABA-B agonists, deserves further study.

Diagnostic options for patients with refractory GERD

Patients with refractory gastroesophageal reflux disease (GERD) are those who have persistent symptoms while being treated with proton pump inhibitors (PPIs). One third of GERD patients requiring a daily PPI are estimated to eventually experience treatment failure. These patients are usually referred for further investigation to confirm the presence of GERD or to identify other entities as the cause of symptoms. Tools that can be used in this diagnostic process include upper gastrointestinal endoscopy with analysis of esophageal biopsies, esophageal pH monitoring, impedance-pH monitoring, and esophageal bilirubin monitoring. The conventional diagnostic approach includes upper gastrointestinal endoscopy and ambulatory pH monitoring while receiving PPI therapy. New diagnostic techniques that may be useful with refractory GERD include impedance-pH monitoring, which is very sensitive in detecting persistent weakly acidic reflux, and bilirubin monitoring, which detects increased esophageal exposure to bile. Gastric pH monitoring should be reserved for patients in whom PPI resistance is suspected.

Contribution of histology to the diagnosis of reflux disease

Histology in reflux disease is still regarded as having low sensitivity and specificity. During the last three decades several histological parameters have been developed, including thickness of basal cell layer, length of epithelial papillae, intraepithelial inflammatory cells and dilation of intercellular spaces. Unfortunately classification of these parameters was often not related to the clinical symptoms of the reflux affected individuals, proper control subjects were often missing and often no interobserver variation was given. Another reason for the proposed low value of biopsies is the fact that biopsies were often taken in a non-standardised way. Recent studies point towards an area of predominantly epithelial damage close to the lesser curvature or around the right oesophageal wall. In parallel, some large, careful studies carried out recently showed a good correlation with the clinical picture of reflux disease due to a standardised biopsy protocol and proper controls. But biopsies are not recommended in all routine classical cases of reflux disease since it is believed that little further information in addition to endoscopy can be obtained. However, histology can deliver much more information than the diagnosis of reflux induced lesions (e.g. the exclusion of malignancy or other oesophageal diseases).

Nonerosive reflux disease: a pathophysiologic perspective

Nonerosive reflux disease (NERD) is the most common phenotype of gastroesophageal reflux disease. By definition, patients with NERD have typical reflux symptoms caused by the intraesophageal reflux of gastric contents but have no visible esophageal mucosal injury. This is in contrast to patients with reflux esophagitis, also known as erosive reflux disease, and Barrett's esophagus, who have obvious esophageal mucosal injury on endoscopy. Only 50% of patients with NERD have pathologic esophageal acid contact time (ACT) as detected on 24-hour pH monitoring (ie, NERD-positive). NERD patients with physiologic esophageal ACT and good temporal correlation of symptoms with reflux events (symptom index > 50% or symptom-association probability > 95%) are considered to have esophageal hypersensitivity (ie, NERD-negative). Finally, patients with physiologic esophageal ACT but poor symptom-reflux correlation are now considered to have functional heartburn and not NERD. NERD-positive patients have motor dysfunction and acidic reflux abnormalities that are similar to patients with reflux esophagitis and Barrett's esophagus, whereas NERD-negative patients have minimal abnormalities that are not much different than healthy controls. The histopathologic feature most indicative of NERD is the presence of dilated intercellular spaces within squamous epithelium, an ultrastructural abnormality readily identified on transmission electron microscopy and on light microscopy.

Pathophysiology of gastroesophageal reflux disease

The pathophysiology of gastroesophageal reflux disease remains incompletely understood. Its hallmark symptom is "heartburn" and, on the basis of endoscopy, those with heartburn are subdivided into nonerosive reflux disease and erosive esophagitis. Although subjects with nonerosive reflux disease have no gross damage on endoscopy, a characteristic histopathologic feature of this disease is present on endoscopic biopsy. This lesion is known as "dilated intercellular spaces," a finding present within squamous epithelium. This report details how acid in contact with a damaged esophageal epithelium leads to heartburn and to the progression of nonerosive reflux disease to erosive esophagitis. It also addresses the fact that esophageal pH monitoring may be normal in a significant number of subjects with heartburn, particularly with nonerosive reflux disease, and details how this observation suggests that in addition to defects in the antireflux barrier, for example, transient lower esophageal sphincter relaxations and low lower esophageal sphincter pressure, defects in tissue resistance created by contact with ingested products may also be etiologic in some subjects with gastroesophageal reflux disease.

Esophageal dilated intercellular spaces (DIS) and nonerosive reflux disease

Esophageal mucosal dilated intercellular spaces (DIS) are frequently observed in patients with nonerosive reflux disease (NERD) and patients with esophagitis. The specificity of DIS is questionable, as it is present in up to 30% of asymptomatic healthy subjects and in patients with other esophageal disorders. DIS occurs in parallel with a drop in potential difference, diminished transepithelial resistance, and increased esophageal mucosal permeability. These alterations arise with exposure to acid and pepsin during gastroesophageal reflux, but the exact pathway of damage to the intercellular junctions remains unclear and seems to be multifactorial. Other noxious contents of the refluxate, such as bile acids, are harmful and DIS can also be induced by acute psychological stress. DIS can be assessed quantitatively with electron microscopy (EM), but it is also recognizable with light microscopy (LM). DIS can disappear after treatment with proton pump inhibitors (PPI); however, this is not the case in all NERD patients. A recent study showed that patients with NERD who are refractory to PPI might still have DIS; and animal experiments showed that persistence of DIS might be due to esophageal mucosal exposure to bile acids and/or psychological stress. In conclusion, DIS is a frequent but nonspecific histological feature of NERD. It can be caused by acid reflux, but bile acids in the refluxate and/or psychological stress can modulate the development or persistence of DIS. Although a causal relationship between DIS and heartburn has been proposed, it still needs to be proven and the underlying mechanisms investigated before considering DIS as a target for treatment of NERD.

Functional heartburn, nonerosive reflux disease, and reflux esophagitis are all distinct conditions—A debate: Pro

Gastroesophageal reflux disease (GERD) traditionally has been approached as a spectrum-continuum, suggesting that patients may progress over time and develop a more severe esophageal mucosal involvement. The spectrum-continuum conceptual model had a profound impact on the research priorities in GERD, as well as on proposed diagnostic algorithms and therapeutic strategies. Natural course studies in GERD are almost always retrospective and commonly afflicted with a plethora of shortcomings. Factors that affect quality of natural course studies in GERD include the following: index endoscopy results are taken at face value; antireflux treatment is consumed until index endoscopy and/or offered during the follow-up phase; pathophysiologic, anatomic, and genetic factors are overlooked; and lack of confirmation of the durability of the new esophageal mucosal finding. Functional heartburn is common and likely to affect a large subset of patients presenting with heartburn. Evidence to support progression of functional heartburn to nonerosive reflux disease (NERD), erosive esophagitis, or Barrett's esophagus is very scarce. The largest population-based or longest-duration natural course studies report that only 10% of patients progress from NERD to erosive esophagitis over time. The other GERD patients remained within their respective phenotypic presentations of GERD.

Increased esophageal mucosal/submucosal blood flow in patients with gastroesophageal reflux disease: normalization by treatment with a proton pump inhibitor

BACKGROUND AND AIM

Mucosal injury caused by gastroesophageal reflux may result in changes in esophageal mucosal blood flow. Little is known about esophageal mucosal blood flow in patients with gastroesophageal reflux disease (GERD). Here we examined esophageal mucosal blood flow and the effects of treatment in patients with GERD.

METHODS

The subjects included 41 cases (21 males and 20 females, mean age 64.2 years) in whom endoscopy was warranted in patients complaining of heartburn and/or regurgitation. We also studied six normal control subjects. Patients underwent endoscopy, laser Doppler flow meter measurements, and endoscopic ultrasonography before and after treatment.

RESULTS

Esophageal mucosal/submucosal blood flow was increased in patients with GERD compared with the control patients. The thickness of the whole esophageal wall and that of the mucosal and submucosal layers of the esophagus correlated significantly with esophageal mucosal/submucosal blood flow. The increased esophageal mucosal/submucosal blood flow significantly decreased after 4 weeks' treatment with lansoprazole, a proton pump inhibitor.

CONCLUSION

Our results indicated that the pathophysiology or underlying mechanisms of GERD includes increased esophageal mucosal/submucosal blood flow, which correlates with the thickness of the esophageal wall, but is reversible and responds to treatment with lansoprazole. This suggests that proton pump inhibitors can effectively treat GERD and promote histological normalization of the mucosa and submucosa in the lower esophagus.

Claudin-18: a dominant tight junction protein in Barrett's esophagus and likely contributor to its acid resistance

Barrett's esophagus (BE) is a specialized columnar epithelium (SCE) that develops as replacement for damaged squamous epithelium (SqE) in subjects with reflux disease, and as such it is apparently more acid resistant than SqE. How SCE resists acid injury is poorly understood; one means may involve altered tight junctions (TJs) since the TJ in SqE is an early target of attack and damage by acid in reflux disease. To assess this possibility, quantitative RT-PCR for 21 claudins was performed on endoscopic biopsies on SCE of BE and from healthy SqE from subjects without esophageal disease. In SCE, Cldn-18 was the most highly expressed at the mRNA level and this finding is paralleled by marked elevation in protein expression on immunoblots. In contrast in SqE, Cldn-18 was minimally expressed at the mRNA level and undetectable at the protein level. Immunofluorescence studies showed membrane localization of Cldn-18 and colocalization with the tight junction protein, zonula occludens-1. When Cldn-18 was overexpressed in MDCK II cells and mounted as monolayers in Ussing chambers, it raised electrical resistance and, as shown by lower dilution potentials to a NaCl gradient and lower diffusion potentials to acidic gradients, selectively reduced paracellular permeability to both Na(+) and H(+) compared with parental MDCK cells. We conclude that Cldn-18 is the dominant claudin in the TJ of SCE and propose that the change from a Cldn-18-deficient TJ in SqE to a Cldn-18-rich TJ in SCE contributes to the greater acid resistance of BE.

Reflux oesophagitis in children; the role of endoscopy. A multicentric Italian survey

BACKGROUND

The decision whether to perform endoscopy in children with suspected reflux oesophagitis is not a straightforward one. Few symptoms are specific for oesophagitis and the diagnosis is not always correlated even to visual findings on endoscopy.

AIM

The aim of this study was to define the role of endoscopy and especially of histology in the diagnosis of reflux oesophagitis and to examine the correlations between symptoms, endoscopic findings and histology in children with suspected gastroesophageal reflux disease.

PATIENTS AND METHODS

One hundred and thirty-six patients with a clinical diagnosis of reflux oesophagitis, aged 1-18 years (mean 8.43; standard deviation +/-4.4), were enrolled from 12 Italian Paediatrics Gastroenterology Centres; symptom score, endoscopic and histologic oesophagitis scores were observed before and after therapy with proton pump inhibitors.

RESULTS

Before therapy, a high correlation between the prevailing symptom score and endoscopic score was demonstrated, but not with histologic score: there was a significant tendency for histologic grade to exceed visual findings. After therapy, endoscopic score and histologic score were significantly improved.

CONCLUSIONS

Oesophageal biopsies increase the diagnostic accuracy of upper endoscopy. Histologic grading is often much more important than the endoscopic appearance, so that endoscopic oesophageal biopsies are very important aids in the diagnosis of oesophagitis. Appropriate clinical evaluation of symptoms must occur before endoscopic examination.

Influence of radiofrequency energy delivery at the gastroesophageal junction (the Stretta procedure) on symptoms, acid exposure, and esophageal sensitivity to acid perfusion in gastroesophagal reflux disease

Several studies have demonstrated that radiofrequency energy delivery at the gastroesophageal junction (the Stretta procedure) induces symptom relief in gastroesophageal reflux disease (GERD), although improvement of acid exposure on pH monitoring was usually limited. A role for decreased esophageal sensitivity has been suggested. Our aim was to evaluate the influence of Stretta on symptoms, acid exposure, and sensitivity to esophageal acid perfusion in GERD. Thirteen patients with established proton pump inhibitor (PPI)-dependent GERD (three males; mean age, 51+/-10 years) participated in the study. Before and 6 months after the procedure symptom score, pH monitoring and Bernstein acid perfusion test were performed. The latter was done by infusing HCl (pH 0.1) at a rate of 6 ml/min 15 cm proximal to the gastroesophageal junction for a maximum of 30 min or until the patients experienced heartburn. Results were compared by Student's t-test. Stretta procedure time was 51+/-4 min and no complications occurred. After 6 months, the symptom score was significantly improved (12.5+/-2.0 to 7.5+/-2.1; P<0.05), seven patients no longer needed daily PPI, and acid exposure was significantly decreased (11.6%+/-1.6% to 8.5%+/-1.8% of time pH<4; P<0.05). The time needed to induce heartburn during acid perfusion decreased from 9.5+/-2.3 to 18.1+/-3.4 min (P=0.01), and five patients became insensitive to 30-min acid perfusion, versus none at baseline (P=0.04). In conclusion, the Stretta procedure induces subjective improvement of GERD symptoms and decreases esophageal acid exposure. In addition, esophageal acid sensitivity is decreased 6 months after the Stretta procedure. The mechanism underlying this finding and its relevance to symptom control require further studies.

Review article: the pathophysiology of gastro-oesophageal reflux disease

BACKGROUND

Gastro-oesophageal reflux disease (GERD) is a common condition that develops when the reflux of stomach contents causes troublesome symptoms and/or complications.

AIM

To review the current knowledge on the underlying factors contributing to GERD, with particular emphasis on the most recent research.

METHODS

Literature searches were conducted in Medline and EMBASE. The abstracts from recent large congresses were also reviewed to ensure coverage of the latest findings.

RESULTS

The pathophysiological factors causing GERD can be split into those inducing greater exposure of the oesophagus to stomach contents, and those that provide increased perception of reflux or increased mucosal damage. Transient lower oesophageal sphincter relaxations, which are likely to be triggered by gastric distension, appear to be a key physiological cause of GERD. Excessive reflux may also be provoked by impaired oesophageal or gastric clearance mechanisms. Pre-epithelial, epithelial and post-epithelial defences all normally protect the oesophagus from injury, and may be compromised in individuals with GERD. Heartburn could also be caused by oesophageal hypersensitivity as a result of visceral neural pathway dysfunction.

CONCLUSION

The pathophysiology of GERD is multifactorial, and abnormalities in the gastro-oesophageal junction, the stomach, the oesophagus and the nervous system may all contribute to this disease state.