A novel rat model to determine interaction between reflux oesophagitis and bronchial asthma

Extra-esophageal gastroesophageal reflux disease and asthma: understanding this interplay

Gastroesophageal reflux disease (GERD) is a condition that develops when there is reflux of stomach contents, which typically manifests as heartburn and regurgitation. These esophageal symptoms are well recognized; however, there are extra-esophageal manifestations of GERD, which include asthma, chronic cough, laryngitis and sinusitis. With the rising incidence of asthma, there is increasing interest in identifying how GERD impacts asthma development and therapy. Due to the poor sensitivity of endoscopy and pH monitoring, empiric therapy with proton pump inhibitors (PPIs) is now considered the initial diagnostic step in patients suspected of having GERD-related symptoms. If unresponsive, diagnostic testing with pH monitoring off therapy and/or impedance/pH monitoring on therapy, may be reasonable in order to assess for baseline presence of reflux with the former and exclude continued acid or weakly acid reflux with the latter tests. PPI-unresponsive asthmatics, without overt regurgitation, usually have either no reflux or causes other than GERD. In this group, PPI therapy should be discontinued. In those with GERD as a contributing factor acid suppressive therapy should be continued as well as optimally treating other etiologies requiring concomitant treatment. Surgical fundoplication is rarely needed but in those with a large hiatal hernia, moderate-to-severe reflux by pH monitoring surgery might be helpful in eliminating the need for high-dose acid suppressive therapy.

Airway hyperresponsiveness induced by repeated esophageal infusion of HCl in guinea pigs

Gastroesophageal reflux is a common disorder closely related to chronic airway diseases, such as chronic cough, asthma, chronic bronchitis, and chronic obstructive disease. Indeed, gastroesophageal acid reflux into the respiratory tract causes bronchoconstriction, but the underlying mechanisms have still not been clarified. This study aimed to elucidate functional changes of bronchial smooth muscles (BSMs) isolated from guinea pigs in an animal model of gastroesophageal reflux. The marked airway inflammation, hyperresponsiveness and remodeling were observed after guinea pigs were exposed to intraesophageal HCl infusion for 14 days. In addition, contractile responses to acetylcholine (ACh), KCl, electrical field stimulation, and extracellular Ca(2+) were greater in guinea pigs infused with HCl compared with control groups. The L-type voltage-dependent Ca(2+) channels (L-VDCC) blocker, nicardipine, significantly inhibited ACh- and Ca(2+)-enhanced BSM contractions in guinea pigs infused with HCl. The Rho-kinase inhibitor, Y27632, attenuated ACh-enhanced BSM contractions in guinea pigs infused with HCl. Moreover, mRNA and protein expressions for muscarinic M2 and M3 receptors, RhoA, and L-VDCC in BSM were detected by real-time PCR and Western blot. Expressions of mRNA and protein for muscarinic M3 receptors, RhoA, and L-VDCC were greater than in BSM of HCl-infused guinea pigs, whereas levels of muscarinic M2 receptors were unchanged. We demonstrate that acid infusion to the lower esophagus and, subsequently, microaspiration into the respiratory tract in guinea pigs leads to airway hyperresponsiveness and overactive BSM. Functional and molecular results indicate that overactive BSM is the reason for enhancement of extracellular Ca(2+) influx via L-VDCC and Ca(2+) sensitization through Rho-kinase signaling.

Experimental study for the mechanism of gastroesophageal-reflux-associated asthma

Epidemiologic studies have shown a strong association between gastroesophageal reflux (GER) and asthma, especially in children. Diagnosing GER can be difficult in some patients when GER presents solely with asthma. The aim of this study was to explore the relationship between GER and asthma with animal model. Sixty rats were randomly divided into six equal groups, GER group, GER-associated-asthma group, allergic asthma group, and their control groups. The cytokine levels and concentration of inflammatory cells in bronchoalveolar lavage (BAL) were determined. The BAL of the rats with allergic asthma contained higher concentration of Interleukin-5 (IL-5) and more eosinophils than those of rats with GER-associated-asthma. This demonstrates that assaying the concentrations of IL-5 and inflammatory cells in BAL may be an effective method of distinguishing GER-associated asthma from allergic asthma.

Role of Th-2 cytokines in the development of Barrett's esophagus in rats

BACKGROUND

Barrett's esophagus is characterized by a distinct Th-2-predominant cytokine profile, unlike the pro-inflammatory nature of reflux esophagitis. The aim of this study was to examine the role of Th-2 cytokines during the development of Barrett's esophagus, using a rat model.

METHODS

Barrett's esophagus was induced by Levrat's esophagojejunostomy technique in Brown-Norway (BN) rats. Rats were killed at 8, 15, 30, and 50 weeks after the operation. We studied the incidences of esophagitis and Barrett's esophagus, and the mRNA expression of cytokines and CDX2 by real-time reverse transcriptase-polymerase chain reaction and immunohistochemical staining. Finally, we compared the incidence of Barrett's esophagus in BN rats with that in Sprague-Dawley (SD) rats.

RESULTS

Esophagitis was found in all rats. Barrett's esophagus appeared 8 weeks after the operation, and its incidence and length increased over time. Levels of Th-2 cytokines such as interleukin (IL)-4, IL-10, and IL-13 were significantly increased in Barrett's esophagus as compared to those in non-Barrett's esophagus, while there were no differences in the levels of pro-inflammatory cytokines. The peak of elevated IL-4 mRNA was observed before that of CDX2 mRNA. IL-4 was co-localized in CD4-positive cells and CDX2-positive goblet cells. The incidence of Barrett's esophagus was more common in BN rats (8/10, 80%) than in SD rats (2/7, 28%) at 30 weeks.

CONCLUSION

Th-2 cytokines, especially IL-4, may play a crucial role in the development of Barrett's esophagus in an early phase. These results provide understanding of the pathogenesis of Barrett's esophagus from the aspect of the Th-2 immune response.

Erosive esophagitis worsens reflux signs and symptoms in asthma patients without affecting pulmonary function tests

OBJECTIVES

To determine whether erosive esophagitis (EO) worsens reflux signs and symptoms and affects pulmonary function test in asthma patients.

METHODS

Sixty asthma patients with gastroesophageal and laryngopharyngeal reflux symptoms were included. Spirometry, reversibility test, esophagogastroscopy, laryngoscopy, and esophagogastroscopic biopsies were conducted.

RESULTS

EO was diagnosed in 25% (n = 15) of the patients. The remaining 45 patients were placed into the non-erosive esophagitis (NEO) group. Of the 15 EO patients, grade 1 esophagitis was identified in 75% (n = 9), grade 2 in 12.5% (n = 3), and grade 3 in 12.5% (n = 3). Pulmonary function test results were not significantly different between the EO and NEO groups. Gastroesophageal and laryngopharyngeal reflux symptoms such as regurgitation, dysphagia, dyspnea, globus sensation, dysphonia, and sore throat were more frequent in EO patients than in the NEO group. The reflux finding score (RFS) was 7.33 and 4.55 in EO and NEO patients, respectively (p < .001). Posterior commissure hypertrophy was the most common laryngoscopic finding in both of the groups followed by diffuse laryngeal edema, erythema, and pseudosulcus.

CONCLUSIONS

Gastroesophageal and laryngopharyngeal reflux symptoms were more frequent in EO patients than in the NEO group. The laryngoscopic findings of laryngopharyngeal reflux were more severe and the RFS was significantly higher in EO patients than in NEO patients. The presence of EO seems to be associated with an increase in reflux without affecting pulmonary function as EO did not cause a significant decrease in pulmonary function tests.

The pharyngeal mucosa is not involved in eosinophilic oesophagitis

BACKGROUND

Eosinophilic oesophagitis is thought to be an isolated oesophageal disease associated with biopsy-verified eosinophilia of the squamous cell epithelium of the oesophagus. Food- or aeroallergens have been suggested to be the cause of eosinophilic oesophagitis; however, as these allergens pass through the pharynx sharing the same squamous cell epithelium, eosinophilic infiltration could be expected also here. Whether this is true or not has hitherto not been clarified.

AIM

To find out whether eosinophilia is present also within the pharyngeal epithelium in patients with eosinophilic oesophagitis.

METHODS

In all, 10 patients (median age 34, range 15-70) with biopsy-verified eosinophilic oesophagitis [peak count >20 eosinophils per high power field (hpf)] were biopsied also in the pharynx. The biopsies underwent histopathological examination and at each level, the peak number of eosinophils per hpf was counted.

RESULTS

None of the patients examined was found to have eosinophilia within the squamous cell epithelium of the pharynx (median peak count 0, range 0-1).

CONCLUSIONS

The pronounced eosinophilic infiltration in eosinophilic oesophagitis appears to be an isolated oesophageal phenomenon not shared by the adjoining organ sites and in particular, not by the pharynx. This may have implications for future research.