Esophagoprotective potential of cisapride. An additional benefit for gastroesophageal reflux disease

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.

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

Background:

It has been previously demonstrated that patients with reflux esophagitis exhibit a significant impairment in the secretion of salivary protective components versus controls. However, the secretion of salivary protective factors in patients with nonerosive reflux disease (NERD) is not explored. The authors therefore studied the secretion of salivary volume, pH, bicarbonate, nonbicarbonate glycoconjugate, protein, epidermal growth factor (EGF), transforming growth factor alpha (TGF-α) and prostaglandin E2 in patients with NERD and compared with the corresponding values in controls (CTRL).

Methods:

Salivary secretion was collected during basal condition, mastication and intraesophageal mechanical (tubing, balloon) and chemical (initial saline, acid, acid/pepsin, final saline) stimulations, respectively, mimicking the natural gastroesophageal reflux.

Results:

Salivary volume, protein and TGF-α outputs in patients with NERD were significantly higher than CTRL during intraesophageal mechanical (P < 0.05) and chemical stimulations (P < 0.05). Salivary bicarbonate was significantly higher in NERD than CTRL group during intraesophageal stimulation with both acid/pepsin (P < 0.05) and saline (P < 0.01). Salivary glycoconjugate secretion was significantly higher in the NERD group than the CTRL group during chewing (P < 0.05), mechanical (P < 0.05) and chemical stimulation (P < 0.01). Salivary EGF secretion was higher in patients with NERD during mechanical stimulation (P < 0.05).

Conclusions:

Patients with NERD demonstrated a significantly stronger salivary secretory response in terms of volume, bicarbonate, glycoconjugate, protein, EGF and TGF-α than asymptomatic controls. This enhanced salivary esophagoprotection is potentially mediating resistance to the development of endoscopic mucosal changes by gastroesophageal reflux.

A distinct salivary secretory response mediated by the esophago-salivary reflex in patients with Barrett's esophagus: its potential pathogenetic implications

PURPOSE

A significantly compromised epidermal growth factor (EGF) secretion by basal parotid saliva may contribute to the development of Barrett's esophagus (BE). The rate of secretion of EGF as well as a wide spectrum of protective factors in total basal and stimulated saliva in BE patients remains to be explored. We therefore studied the rate of secretion of salivary buffers, glycoconjugate, protein, EGF, transforming growth factor α (TGFα) and prostaglandin E₂ (PGE₂), evoked by esophago-salivary reflex, in patients with BE and controls (CTRL).

MATERIAL/METHODS

Salivary secretion was collected during basal condition, mastication, and intraesophageal mechanical and chemical stimulations respectively, mimicking the natural gastroesophageal reflux scenario.

RESULTS

Salivary pH in BE was significantly lower than in controls during mechanical (p<0.001) and chemical stimulations (p<0.001). Bicarbonate and protein outputs in BE were significantly lower during mechanical (p<0.05) and chemical stimulations (p<0.01). The non-bicarbonate and glycoconjugate outputs in BE were lower during chemical stimulation (p<0.05) and during mechanical (p<0.05) and chemical stimulations (p<0.05) respectively. The rate of salivary EGF output in BE was significantly lower during mechanical stimulation (p<0.05). We observed a higher TGFα output during mastication (p<0.05) and PGE2 secretion during basal and masticatory condition (p<0.05) in BE.

CONCLUSIONS

Patients with BE demonstrated significantly compromised salivary pH and rate of secretion of bicarbonate, non-bicarbonate, glycoconjugate, protein and EGF. This impairment could potentially predispose to the development of accelerated esophageal mucosal injury. Potential restoration of this impairment by masticatory stimulation of salivary secretion using sugarless chewing gum justifies further clinical exploration.

Effect of mosapride combined with esomeprazole improves esophageal peristaltic function in patients with gastroesophageal reflux disease: a study using high resolution manometry

BACKGROUND

Whether addition of prokinetics to proton pump inhibitors improves esophageal peristalsis and symptoms in patients with gastroesophageal reflux disease (GERD) remains unknown.

AIM

We evaluated the effect of mosapride, a 5-HT4 agonist, and PPI cotherapy in patients with GERD on esophageal motility using high-resolution manometry (HRM).

METHOD

This study was designed as a double-blind, randomized, placebo-controlled trial. Patients with GERD were allocated to a group either taking 40 mg esomeprazole plus 30 mg mosapride or taking esomeprazole plus placebo. Symptom assessment and the HRM study were conducted before drug treatment and after 4 weeks.

RESULTS

Of 50 patients enrolled, 24 in the mosapride group (49 years old, 15 males) and 19 in the placebo group (43 years old, nine males) completed the study. Approximately 79 % of the patients had normal peristaltic function. Treatment response was not different between the two groups (79 vs. 68 %). Mosapride cotherapy tended to yield better response in patients with dyspepsia than those without dyspepsia (92 vs. 67 %). Lower esophageal sphincter pressure didn't change in both groups. Intrabolus pressure decreased in the mosapride group (3.4 ± 3.5 mmHg to 1.4 ± 4.1 mmHg, P < 0.05). Distal esophageal amplitude increased in the mosapride group and not in the placebo group (81 ± 34 to 89 ± 29 mmHg vs. 82 ± 32 to 83 ± 31 mmHg).

CONCLUSION

Adding mosapride on esomeprazole improved esophageal contractability and lowered intrabolus pressure in patients with GERD. Mosapride and esomeprazole cotherapy tended to yield better response in patients with concomitant dyspepsia.

Effects of Rikkunshito (TJ-43) on Esophageal Motor Function and Gastroesophageal Reflux

Background/Aims

Rikkunshito (TJ-43), an herbal medicine, has been demonstrated to relieve gastroesophageal reflux symptoms. However, the effects of TJ-43 on esophageal motor functions have not been fully determined. This double-blind crossover study was performed to investigate the effects of TJ-43 on esophageal motor functions and gastroesophageal reflux.

Methods

The subjects were 10 normal male volunteers. Lower esophageal sphincter pressure and esophageal body peristaltic contractions with and without 1-week administration of TJ-43 were examined in a crossover fashion. Post-prandial gastroesophageal reflux was also determined using a multi-channel impedance pH dual monitor.

Results

TJ-43 at a standard dose of 7.5 g/day did not significantly augment esophageal peristaltic contraction pressure measured in the proximal, middle and distal segments of the esophagus, whereas increment of resting lower esophageal sphincter pressure was observed in a supine position. In addition, TJ-43 administration did not decrease post-prandial gastroesophageal acid, non-acid reflux events or accelerate esophageal clearance time.

Conclusions

TJ-43 at a standard dose did not have a significant effect on esophageal motor activity or gastroesophageal reflux in healthy adults.

Effects of mosapride on esophageal functions and gastroesophageal reflux

BACKGROUND AND AIM

A substantial number of patients with gastroesophageal reflux disease show symptomatic resistance to high-dose proton pump inhibitors. In those cases, prokinetics are possible candidates for treatment. The aim of the present study was to determine whether mosapride, a prokinetic agent, stimulates esophageal functions, and prevents acidic and non-acidic gastroesophageal reflux.

METHODS

Normal volunteers (nine and 13 for two experiments, respectively) were enrolled. Salivary secretion, esophageal peristaltic contractions, and resting lower esophageal sphincter pressure with and without mosapride administration were recorded using a cross-over protocol. Post-prandial acidic and non-acidic reflux levels were also recorded.

RESULTS

Mosapride at a standard dose of 15 mg/day did not stimulate salivary secretion or any esophageal motor functions. It also failed to prevent acidic and non-acidic post-prandial gastroesophageal reflux.

CONCLUSIONS

Mosapride at 15 mg/day, a standard dose in Japan, did not change the esophageal motility and salivary secretion in healthy volunteers. Future study on a larger number of individuals with higher dose of mosapride is worthwhile.

Significant enhancement of esophageal pre-epithelial defense by tegaserod: implications for an esophagoprotective effect

BACKGROUND & AIMS

Tegaserod, a serotonin 5-hydroxytryptamine (5-HT)4 receptor agonist, is thought to stimulate intestinal secretions. The aim of the current study was to assess the effect of tegaserod vs placebo on salivary and esophageal protective factors in patients with gastroesophageal reflux disease (GERD).

METHODS

This study was a randomized, double-blind, placebo-controlled, cross-over trial in 38 GERD patients treated with tegaserod 6 mg twice a day vs placebo. Salivary samples were collected basally and during mastication. In addition, in 32 GERD patients, salivary and esophageal secretions also were collected during infusion of NaCl, HCl/pepsin, and NaCl in a consecutive fashion using a specially designed esophageal catheter. Saliva and esophageal perfusates were assessed for the pH, volume, content of buffers, protein, mucin, epidermal growth factor (EGF), transforming growth factor alpha (TGFalpha), and prostaglandin E (PGE)2 and analyzed statistically.

RESULTS

Salivary flow rates during administration of tegaserod increased over corresponding values during both basal conditions (P < .01) and mastication (P < .001). The rate of secretion of salivary bicarbonate and nonbicarbonate buffers also increased in basal conditions (P < .001 and P < .01, respectively) and during mastication (P < .05 and P = .05). Salivary EGF increased during mastication (P < .05), whereas PGE2 and TGF alpha increased in basal conditions (P < .05 and P < .01). Esophageal perfusate volumes increased during administration of tegaserod in basal conditions (P < .05), whereas esophageal EGF secretion increased after mucosal exposure to HCl/pepsin and subsequent final perfusion with NaCl (P < .05).

CONCLUSIONS

Significant stimulatory impact of 5-HT4 agonist on several salivary protective factors as well as esophageal EGF secretion may have esophagoprotective implications in patients with GERD and may help to address new therapies in the future.

Relationship between acceleration of gastric emptying and oesophageal acid exposure in patients with endoscopy-negative gastro-oesophageal reflux disease

OBJECTIVE

A delay in gastric emptying has been reported in patients with gastro-oesophageal reflux disease (GORD), but its role in increasing the number of reflux episodes is still debated. The aim of this study was to assess the relationship between acceleration of gastric emptying and gastro-oesophageal reflux in patients with endoscopy-negative GORD and pathological oesophageal acid exposure.

MATERIAL AND METHODS

Twelve patients (7 M, age range 24-65 years) underwent 6-h postprandial (2.1 MJ meal) combined gastric emptying by real-time ultrasonography and intra-oesophageal pH monitoring after cisapride (20 mg b.i.d.) and placebo for 3 days, on two separate occasions at least 7 days apart in double-blind randomized order. Gastric emptying after placebo was also measured in 12 healthy volunteers (7 M, age range 25-54 years).

RESULTS

In the patients' group, the area under the emptying time curve was greater (p<0.01), and half and total emptying times prolonged (p<0.01) compared to the healthy subjects, 115 min (mean)+/-6 (SEM) versus 86+/-6 and 232 min+/-16 versus 160+/-7, respectively. Cisapride accelerated both half- and total gastric emptying (p<0.02): -22 min (mean); -10 to -34 (95% CI) and -48 min; -10 to -85, respectively, decreased both percentage of time at pH < 4 (p<0.01) and number of reflux episodes (p<0.05). However, no relationship was found between changes in gastric emptying and in the reflux variables by linear regression analysis (R2<0.005).

CONCLUSION

The emptying rate of the whole stomach is not a major determinant of gastro-oesophageal reflux.

The diagnosis and management of gastro-oesophageal reflux in infants

Gastro-oesophageal reflux (GOR) and gastro-oesophageal reflux disease (GORD) occur frequently during the first months of life. Gastro-oesophageal reflux may be a primary gastro-intestinal motility disorder, but it may also be secondary to other conditions such as cow's milk protein allergy. Objective diagnosis can be difficult because there may be absence of correlation between history, results of pH monitoring and histology. Severe GORD may cause minor symptoms, and minor GOR may cause severe symptoms. Several different therapeutic interventions exist. Simply stated, thickened formula reduces regurgitation and alginates and proton pump inhibitors can be used to decrease acid GOR, depending on the severity of the GORD. Efficacy data of prokinetic drugs are either lacking or disappointing. Regarding side-effects, interest has been focused on cisapride, although other molecules have similar effects. Long-term side-effects such as the nutritional consequence of therapeutic management have been insufficiently studied, especially for the acid-reducing molecules.

Comparison of efficacy of pantoprazole alone versus pantoprazole plus mosapride in therapy of gastroesophageal reflux disease: a randomized trial

The present study aimed to compare the efficacy for the therapy of GERD of pantoprazole alone with a combination of pantoprazole and mosapride. The study was a prospective, randomized trial involving 68 patients suffering heartburn and/or regurgitation at least twice a week for 6 weeks. Sixty-one patients consented to be randomized to receive either pantoprazole 40 mg b.i.d. (n = 33, group A) or pantoprazole 40 mg b.i.d. plus mosapride 5 mg t.d.s. (n = 28, group B) for 8 weeks. Twenty-four-hour esophageal pH-metry and endoscopy were conducted at recruitment and endoscopy was repeated at 8 weeks in all the patients studied. There were no differences in symptomatic responses to therapy between the groups (69.7% vs 89.2%; P = 0.11). The mean symptom score after 8 weeks was significantly lower in group B (3.78 +/- 3.62 vs 1.67 +/- 2.09; P = 0.009). Nonerosive esophagitis was present in 29 patients. In patients with nonerosive GERD there was no significant difference in symptomatic response to either regimen (17/20 in group A and 7/9 in group B responded; P = 0.63). In erosive esophagitis, symptomatic responses occurred more frequently in group B, 18/19 (94.7%), than in group A, 6/13 (46.2%; P = 0.003). However endoscopic healing of esophagitis occurred equally with either regimen (6/11, 54.5% in group A; 12/17, 70.5% in group B; P = 0.44). In nonerosive GERD, the addition of mosapride offers no benefit over pantoprazole alone. A combination of pantoprazole and mosapride is more effective than pantoprazole alone in providing symptomatic relief to patients with erosive GERD.

Progress with novel pharmacological strategies for gastro-oesophageal reflux disease

Gastro-oesophageal reflux disease (GORD) is a chronic disorder characterised by an increased exposure of the oesophagus to intragastric contents. Currently, GORD symptoms are maintained under control with antisecretory agents, mainly gastric proton pump inhibitors (PPIs). Although impaired oesophageal motility may partly underlie the pathophysiology of GORD, the use of prokinetic agents has been found to be unsatisfactory. To date, novel pharmacological approaches for GORD are mainly related to the control of transient lower oesophageal sphincter (LOS) relaxations (TLOSRs). The majority of patients with GORD have reflux episodes during TLOSRs, which are evoked by gastric distension, mainly occurring after ingestion of a meal. Patients with reflux disease with normal peristalsis and without or with mild erosive disease could potentially benefit from anti-TLOSR therapy. This therapy might also be of value to treat some severe forms of esophagitis in combination with PPIs. GABA-B-receptor agonists are the most promising class of agents identified so far for TLOSR control. The GABA-B-receptor agonist, baclofen, is the most effective compound in inhibiting TLOSRs in humans. Since baclofen has several CNS adverse effects, novel orally available GABA-B agonists are needed for effective and well tolerated treatment of GORD. Endogenous or exogenous cholecystokinin (CCK) causes a reduction in LOS pressure, an increase in TLOSR frequency and a reduction in gastric emptying. In healthy volunteers and patients with GORD, loxiglumide, a selective CCK1-receptor antagonist, was found to reduce the rate of TLOSRs, although its effect on postprandial acid reflux may be modest. Orally effective CCK antagonists are not marketed to date. The anticholinergic agent atropine, given to healthy volunteers and patients with GORD, markedly reduced the rate of TLOSRs. Because of severe gastrointestinal (and other) adverse effects of anticholinergics, including worsening of supine acid clearance and constipation, it is unlikely that this class of drugs will have a future as anti-TLOSR agents on a routine basis. In spite of their effectiveness in reducing TLOSR rate, untoward adverse effects, such as addiction and severe constipation, currently limit the use of morphine and other opioid mu-receptor agonists. The same applies to nitric oxide synthase inhibitors, which are associated with marked gastrointestinal, cardiovascular, urinary and respiratory adverse effects. Animal studies provide promising evidence for the use of cannabinoid receptor 1 agonists, by showing potent inhibition of TLOSRs in the dog, thus opening a new route for clinical investigation in humans. A better understanding of TLOSR pathophysiology is a necessary step for the further development of novel drugs effective for anti-reflux therapy.

The laryngeal and esophageal manifestations of Sjögren’s syndrome

Laryngopharyngeal reflux (LPR) is the syndrome caused by the backflow of gastric contents into the upper aerodigestive tract. Acid and pepsin in the pharynx, larynx, oral cavity, and trachea have been associated with dysphonia, chronic cough, reactive airway disease, middle ear effusion, throat pain, excessive throat mucus, postnasal drip, dental caries, and laryngeal cancer. The symptoms of LPR frequently occur in the absence of heartburn and esophagitis, and, thus, the diagnosis may be elusive. Individuals with Sjögren's syndrome are predisposed to reflux, and a high index of suspicion for LPR must be maintained in all individuals with the disease. This manuscript describes the laryngeal, pharyngeal, and esophageal manifestations of reflux in patients with Sjögren's syndrome and reviews state-of-the-art diagnostic and treatment strategies.

Mechanisms of gastroesophageal reflux and gastroesophageal reflux disease

Gastroesophageal reflux is a physiological phenomenon, occurring with different severity and duration in different individuals. Reflux occurs when this normal event results in the occurrence of symptoms/signs or complications. The pathophysiology of gastroesophageal reflux is complex and diverse, since it is influenced by factors that are genetic, environmental (e.g., diet smoking), anatomic, hormonal, and neurogenic. However, many mechanisms remain incompletely understood. Future research should focus on a better understanding of the physiology of the upper and lower esophageal sphincters, and of gastric motility. The afferent and efferent neural pathways and neuropharmacologic mediators of transient lower esophageal sphincter relaxations and gastric dysmotility require further study. The role of anatomic malformations such as hiatal hernia in children has been underestimated. While therapeutic possibilities are greater in number and largely improved, the outcomes of some treatments are far from satisfactory in many cases. In addition to development of new forms of treatment, research should address better use of currently available medical and surgical treatments.

Effect of cisapride on nocturnal transient lower oesophageal sphincter relaxations and nocturnal gastro-oesophageal reflux in patients with oesophagitis: a double-blind, placebo-controlled study

AIM

To investigate the effect of cisapride, a selective 5-hydroxytryptamine-4 receptor agonist, on the frequency of nocturnal transient lower oesophageal sphincter relaxations and oesophageal acid exposure in patients with gastro-oesophageal reflux disease.

METHODS

In a double-blind, placebo-controlled study, 10 patients with gastro-oesophageal reflux disease (six male and four female; mean age, 54 +/- 10.4 years) were randomly assigned to 5-day treatments with cisapride, 10 mg q.d.s., or placebo, separated by a 2-day washout period before the treatment crossover. Sleep stages, lower oesophageal sphincter tone and oesophageal pH were monitored overnight at the end of each treatment regimen. Gastric emptying was assessed before treatment.

RESULTS

Cisapride decreased the frequency of transient lower oesophageal sphincter relaxations during sleep (1.2 +/- 0.2/h vs. 2.7 +/- 0.5/h with placebo; P=0.004) and oesophageal acid exposure (17.2 +/- 9.9% with placebo vs. 7.2 +/- 4.2% with cisapride; P=0.4). Cisapride increased lower oesophageal sphincter tone from 12.7 +/- 2.8 mmHg with placebo to 16.9 +/- 3.9 mmHg (P=0.03), and decreased heartburn episodes and antacid consumption. All patients had normal gastric retention data over 4 h.

CONCLUSIONS

In patients with gastro-oesophageal reflux disease, cisapride significantly decreased the frequency of transient lower oesophageal sphincter relaxations during sleep and increased lower oesophageal sphincter pressure without changing gastric emptying. We hypothesize, therefore, that 5-hydroxytryptamine-4 mechanisms are important in the control of transient lower oesophageal sphincter relaxations in humans.

Nizatidine and cisapride enhance salivary secretion in humans

BACKGROUND

Salivation plays an important role in the defence of the oesophageal mucosa against gastric acidic reflux and can be evoked by cholinergic stimulation. Both nizatidine and cisapride have been reported to increase acetylcholine concentrations in the cholinergic system.

AIM

To investigate the effect of nizatidine and cisapride on salivary secretion, salivary epidermal growth factor and bicarbonate output.

METHODS

The salivary volume and concentration of salivary epidermal growth factor and bicarbonate were measured after the administration of nizatidine (150 mg), famotidine (20 mg) and cisapride (5 mg) in 30 male healthy volunteers.

RESULTS

Basal and stimulated salivary secretions were found to be increased after the administration of nizatidine and cisapride. In contrast, salivary secretion was not increased by famotidine. Although epidermal growth factor content was not augmented, nizatidine and cisapride administration also increased the bicarbonate output in mastication-stimulated saliva.

CONCLUSIONS

Increased salivary secretion and bicarbonate output induced by nizatidine may be useful for the treatment of patients with gastro-oesophageal reflux disease.

The role of age and salivation in acid clearance in symptomatic patients with gastro-oesophageal reflux disease

BACKGROUND

Cisapride has been shown to have not only prokinetic effects, but also salivary stimulating effects. Both of these mechanisms play an important role in the acid clearance of the oesophagus.

AIM

To access the efficacy of cisapride in facilitating acid clearance in patients with symptomatic gastro-oesophageal reflux disease.

METHODS

Fifteen older adults and 15 younger adults with symptomatic gastro-oesophageal reflux disease completed the study. The acid clearance test was accomplished by infusing 15 mL of 0.1 N HCl into the distal oesophagus, and the number of swallows was determined to achieve an oesophageal pH of 4.0. This was accomplished under baseline conditions and salivary stimulation with a peppermint lozenge. After 1 week of treatment with cisapride (10 mg, q.d.s.), the acid clearance test was repeated.

RESULTS

The lozenge produced a significant decrease in the number of swallows compared to baseline in both groups (P < 0.01). There was a significant decrease in the number of swallows after the treatment with cisapride compared to baseline in both groups (P < 0.01). No significant difference was found in the number of swallows when comparing cisapride with lozenge.

CONCLUSIONS

Cholinergic stimulation of salivation is an effective means of facilitating oesophageal acid clearance. Drugs, such as 5 hydroxytriptamine (5-HT)4-receptor agonists, should be considered as potentially important compounds in the treatment of gastro-oesophageal reflux disease.

Walking and chewing reduce postprandial acid reflux

BACKGROUND

Gastro-oesophageal reflux is worse after meals, and antacids are usually consumed after dietary indiscretion.

AIM

To investigate whether walking or gum chewing affect meal-induced gastro-oesophageal reflux.

METHODS

The study population comprised 12 case subjects with gastro-oesophageal reflux disease and 24 healthy controls. Each subject was studied using pH-metry for 5 h on 3 separate days. After baseline recording of pH for 1 h, all subjects were fed a standard breakfast over a 20-min period. On one of the days, oesophageal pH was recorded after the 20-min eating period for an additional 4 h in the sitting position. On another day, postprandial oesophageal pH was recorded for the first hour whilst walking, and for 3 subsequent hours whilst sitting. During a third day, oesophageal pH was recorded for the first postprandial hour whilst gum-chewing, followed by 3 h of sitting.

RESULTS

Food intake promoted gastro-oesophageal reflux in case subjects with GERD as well as in healthy controls, although postprandial reflux was more pronounced amongst the refluxers than amongst the controls. Chewing gum for 1 h after the meal reduced the acid contact time in both groups, with a more profound effect in refluxers than in controls. Whilst the beneficial effect of 1-h of gum-chewing lasted for up to 3 h in both groups, the beneficial effect of 1-h of walking was apparent only in refluxers, only to a mild degree, and only for a short duration.

CONCLUSIONS

Chewing gum after a meal helps to reduce postprandial oesophageal acid exposure.

Mechanisms of oesophageal mucosal defence

The integrity of the oesophageal mucosa depends upon an equilibrium between aggressive factors, predominantly acid and pepsin, and protective mechanisms. Protective mechanisms operate within the oesophageal mucosa as pre-epithelial, epithelial and post-epithelial defences. Only the protective components of the oesophageal pre-epithelial defence can be tested in vivo in humans. It has been recently demonstrated that human oesophageal submucosal glands elaborate mucous secretion rich in bicarbonate and non-bicarbonate buffers, mucin, prostaglandin E(2), epidermal growth factor (EGF) and transforming growth factor alpha (TGFalpha). This oesophageal secretion, accompanied by similarly protective factors within the swallowed saliva, defines the protective potential of the oesophageal pre-epithelial defence that exists in the form of a mucus-buffer layer covering the oesophageal mucosa and which retards the back-diffusion of hydrogen ions. It has also been demonstrated that patients with severe erosive reflux oesophagitis exhibit qualitative impairment in both the salivary and oesophageal components of the oesophageal pre-epithelial defence. Furthermore, patients with endoscopically negative gastro-oesophageal reflux disease have a significantly stronger oesophageal pre-epithelial defence than patients with erosive reflux oesophagitis. On the other hand, African-Americans, who are less likely to develop erosive reflux oesophagitis, have a stronger oesophageal pre-epithelial defence than do Caucasians. The salivary component of the oesophageal pre-epithelial defence can be enhanced by mastication and the administration of cisapride, whereas oesophageal secretion can only be significantly augmented by cisapride.

The potential role of the esophageal pre-epithelial barrier components in the maintenance of integrity of the esophageal mucosa in patients with endoscopically negative gastroesophageal reflux disease

OBJECTIVE

Patients with gastroesophageal reflux disease (GERD) accompanied by erosive reflux esophagitis (RE) exhibit an impairment within the esophageal pre-epithelial barrier protective components that may facilitate the development and/or progression of the mucosal injury. Little is known, however, whether such impairment is a general phenomenon affecting all patients with GERD or whether this is a characteristic feature only of patients with erosive RE. We therefore studied the rate of secretion of esophageal inorganic and organic protective factors in patients with endoscopically negative [E (-)] GERD and compared these results with the corresponding values in asymptomatic volunteers (CTRL).

METHODS

The study was conducted on 33 white asymptomatic volunteers and 10 white patients with a long history of GERD confirmed by 24-h pH monitoring and a grossly negative upper endoscopy. Esophageal secretion was collected during mucosal exposure to NaCl, HCl, HC/pepsin and NaCl using the esophageal perfusion catheter. In collected samples all investigated parameters were measured.

RESULTS

The pH of esophageal secretion and its content of bicarbonate, EGF, and PGE2 in patients with E (-) GERD and asymptomatic volunteers were similar. Unexpectedly, the rate of esophageal glycoconjugate (predominantly mucin) secretion was significantly higher in patients with E (-) GERD than in controls during perfusion with HCl (p < 0.05). Furthermore, secretion of protein in patients with E (-) GERD was significantly higher than in the control group during the mucosal exposure to HCl/Pepsin (p < 0.05). The nonbicarbonate buffer secretion during perfusion with HCl and HCl/Pepsin as well as the rate of esophageal TGFalpha output during infusion of final saline in patients with E (-) GERD were significantly lower than in CTRL group (p < 0.05).

CONCLUSIONS

Our data indicate that patients with E (-) GERD have an esophageal secretory potential, in terms of glycoconjugate and protein, higher than that in asymptomatic controls. This phenomenon in patients with E (-) GERD may, by enhancing the quantity of the esophageal pre-epithelial barrier, help to prevent the development of erosive esophagitis. A significantly lower esophageal secretory response in patients with E (-) GERD in terms of nonbicarbonate buffers and TGFalpha may facilitate the development of GERD symptoms and histological changes of GERD, respectively.

Diagnosis and management of supra-esophageal complications of reflux disease

Supra-esophageal reflux disease may be manifested in numerous ways, including reflux laryngitis, chronic cough, chronic sinusitis, and dental enamel loss. The mechanisms of pharyngeal and laryngeal reflux are not clearly defined, and standard reflux testing does not consistently demonstrate supra-esophageal reflux. The diagnosis is usually based on clinical suspicion when other causes of symptoms are not found and on the patient's response to empiric acid suppression. With the development of triple-probe pH monitoring, through which pharyngeal pH can be assessed along with esophageal pH, the physician may now be able to demonstrate pharyngeal reflux in relation to patient symptoms. Therapy consists primarily of behavioral modification and aggressive acid suppression, although some alternative therapies exist.

Salivary and gastric epidermal growth factor in patients with Zollinger-Ellison syndrome: its protective potential

OBJECTIVE

Evidence is accumulating that epidermal growth factor (EGF) is a major molecule contributing to the maintenance of the integrity of the upper alimentary tract mucosa before and after injury by acid and pepsin. Patients with Zollinger-Ellison Syndrome (ZES) typically have hypersecretion of acid and pepsin; however, the concentration and rate of secretion of salivary and gastric EGF that could counteract these potentially aggressive factors are unknown. Accordingly, this study was conducted to determine whether EGF affords mucosal protection in ZES patients.

METHODS

The concentration and output of salivary (sEGF) and gastric epidermal growth factor (gEGF) were measured in eight patients with ZES and the results compared to those in 17 patients with nonulcer dyspepsia (NUD), serving as a control group. All patients had normal esophageal and gastric mucosa as determined by endoscopy. Total saliva was collected during 1-h parafilm- and 1-h pentagastrin/parafilm-stimulated conditions, as well as basal and pentagastrin-stimulated gastric juice. The concentration and output of EGF were determined by radioimmunoassay.

RESULTS

The concentration of EGF in saliva collected from ZES patients after parafilm chewing was significantly higher compared to that in NUD patients (4.61 +/- 0.59 vs 2.75 +/- 0.50 ng/ml, p < 0.05). The concentration of EGF in saliva collected after pentagastrin stimulation in ZES patients was also significantly higher than in NUD patients (4.37 +/- 0.73 vs 2.22 +/- 0.37 ng/ml, p < 0.05). Salivary EGF output during parafilm chewing in ZES and NUD were similar (68 +/- 6.4 vs 109 +/- 25.2 ng/h). Salivary EGF output after administration of pentagastrin in ZES and NUD was also similar (66 +/- 6.1 vs 132 +/- 45.4 ng/h). Basal EGF output in the gastric juice of patients with ZES was 3-fold higher than in patients with NUD (801 +/- 73 vs 271 +/- 32 ng/h, p < 0.01). Pentagastrin-stimulated EGF output was similar in both groups (705 +/- 92 vs 675 +/- 168 ng/h).

CONCLUSIONS

Patients with ZES have a significantly higher EGF concentration in saliva and EGF output in basal gastric juice. This elevated content of salivary and gastric EGF in ZES patients may play a protective role in preventing the development of reflux esophagitis and gastric ulcer under the impact of gastric acid and pepsin hypersecretion.

The efficacy of a 40-mg extended-release formulation of cisapride in the treatment of patients with gastro-oesophageal reflux

BACKGROUND

This study was conducted to assess the efficacy of a novel 40-mg extended-release formulation of cisapride in reducing gastro-oesophageal reflux.

METHODS

According to a double-blind, randomized, placebo-controlled design, 19 patients with pathological gastro-oesophageal reflux were treated with extended (40 mg o.d.) or immediate (10 mg q.d.s.) release formulations for two periods of 4 days each (pH-monitoring on day four). Patients received identical treatments in both periods to allow limits of agreement defining equivalent potency of both formulations to be derived from intra-individual variability of treatment effects.

RESULTS

The extended-release formulation decreased total and upright reflux times by 5.5 +/- 1.3% and 8.1 +/- 2.1% (P < 0.001), respectively. It did not change the percentage supine reflux time but diminished the mean duration of reflux episodes by 1.0 +/- 0.4 min (P=0.005). The total number of reflux episodes remained unaltered with both formulations. Immediately-released cisapride decreased total, upright, and supine acid exposures by 5.8 +/- 1.3%, 6.8 +/- 1.6% (P < 0.002) and 3.6 +/- 1.8%, respectively, and mean duration of episodes by 0.9 +/- 0.2 min (P </= 0.05). Equivalent potency for both formulations was accepted in terms of percentage total and upright acid exposure and mean duration of episodes.

CONCLUSIONS

The 40-mg extended-release formulation of cisapride decreases total acid exposure and in this study is equivalent to the conventional immediate-release 10 mg q.d.s. regimen. Cisapride primarily interferes with reflux by improving oesophageal acid clearance.

Reflux laryngitis: pathophysiology, diagnosis, and management

Gastroesophageal reflux disease is felt to be associated with a variety of laryngeal conditions and symptoms of which "reflux laryngitis" is perhaps the most common. The most likely mechanism for laryngeal injury and symptoms is secondary to direct acid and pepsin contact, although studies concerning the cause and effect between gastroesophageal reflux disease and laryngeal disorders are conflicting. Likewise, the most effective method to diagnose such patients is unclear. Empiric treatment of patients with reflux laryngitis has been shown to be effective though none of the studies are controlled.

Relationship between asthma and gastro-oesophageal reflux: significance of endoscopic grade of reflux oesophagitis in adult asthmatics

BACKGROUND

The association between asthma and gastro-oesophageal reflux disease (GERD) is well known. The aim of this study was to elucidate the causal relationship between reflux oesophagitis (RE) and asthma.

METHODS

Seventy-two adult asthmatics were examined regarding their GERD symptoms, and each underwent an endoscopic examination. According to the Los Angeles classification, we divided the patients into three groups: group 1 (n= 52), no mucosal break; group 2 (n= 15), RE corresponding to grades A or B; group 3 (n = 5), RE corresponding to grades C or D. The asthmatics in groups 2 and 3 received anti-reflux treatment for their GERD for 8 weeks. Their morning and evening peak expiratory flow rates (PEFR), daily variability of the PEFR and daily use of an inhalation bronchodilator were compared before and after this treatment.

RESULTS

The percentage of severe asthma and postprandial exacerbation of asthma in group 3 were significantly higher than those in the other two groups. In contrast, the number of eosinophiles and the serum level of immunoglobulin E in group 3 were significantly lower than those in the other two groups. After the antireflux treatment, significant improvements of both PEFR and daily use of the inhalation bronchodilator were observed only in group 3.

CONCLUSIONS

The endoscopic severity of RE is associated with the characteristics of adult asthmatics and the treatment of severe RE improved the asthmatics' condition.

Saliva and esophageal protection

There has been much interest in recent years in the potential protective role of saliva in the esophagus. Variables such as salivary volume and neutralizing capacity have been studied both during basal conditions and in response to esophageal acid exposure, in healthy subjects and in patients with esophagitis. In addition to its known neutralizing capacity, saliva also contains growth factors. These polypeptides (of which epidermal growth factor has been studied most) have cytoprotective and healing properties in various segments of the gastrointestinal tract. Therefore, a deficiency in one or more of these growth factors might be a contributing factor in the development of gastroesophageal reflux disease (GERD) or its complication, such as Barrett's metaplasia. However, human studies have produced contradictory results regarding salivary growth factor deficiency in such patients. Current methods of investigation make it difficult to assess the importance of saliva in GERD. This may be due in part to the multifactorial nature of the disease and the difficulty in long-term, selective manipulation of salivary function in humans. Given the present data in the literature, it is therefore unknown if saliva plays an important role in esophageal protection.

Functional gut disorders: from motility to sensitivity disorders. A review of current and investigational drugs for their management

Functional gut disorders include several clinical entities defined on the basis of symptom patterns (e.g., functional dyspepsia, irritable bowel syndrome, functional abdominal pain, functional abdominal bloating), for which there is no established pathophysiological mechanism. Because there is no well-defined pathophysiological target, treatment should be aimed at symptom improvement. Prokinetics and antispasmodics have been widely used in the treatment of functional gut disorders on the assumption that disordered motility is the underlying cause of symptoms, and symptom improvement is indeed achievable with these compounds in some, but not all, patients with features of hypo- or hypermotility, respectively. In the first part of this review, we cover the basic pharmacology and discuss the rationale for the clinical use of prokinetics and antispasmodics. On the other hand, in the past few years, the explosive growth in the research focusing on visceral sensitivity and visceral reflexes has suggested that at least some patients with functional gut disorders have altered visceral perception. Thus, the second part of the review covers these developments and focuses on studies addressing the issue of drugs modulating visceral sensitivity.

Role of epidermal growth factor (EGF) in oesophageal mucosal integrity

Oesophageal mucosa has well established protective mechanisms, which operate within pre-epithelial, epithelial and post-epithelial compartments. Since refluxed acid and pepsin always act from the luminal side of the mucosa, protective factors like EGF, operating as a part of pre-epithelial defence, are thought to be pivotal in the maintenance of the integrity of the oesophageal mucosa. The significant contribution of salivary EGF to the quality of the oesophageal mucosal barrier has been demonstrated in an experimental setting and in a clinical scenario. Patients with low salivary EGF levels are predisposed to severe oesophageal damage if they develop gastro-oesophageal reflux and are a high-risk group for development of Barrett's oesophagus. Not only the salivary glands but also the human oesophagus has a profound ability to elaborate and release EGF. Some changes in luminal release of EGF during oesophageal mucosal exposure to intraluminal damaging factors imply its role in the oesophageal protective mechanisms. To exert biological effects within the oesophageal mucosal compartment, EGF requires binding to the ligand-binding domain of its receptor. This process results in receptor dimerisation, autophosphorylation and activation of intracellular signal transduction pathways. EGF receptors are localised on the basolateral and luminal aspect of the mucosal cells playing an important role in fast regeneration of oesophageal epithelium through the high mitotic activity of its proliferative zone. An increase in the rate of salivary EGF secretion during masticatory stimulation suggests its potential therapeutic benefit in the treatment of patients with damaged oesophageal mucosa.