A novel murine model of esophageal nonerosive reflux disease: from inflammation to impairment in mucosal integrity

Abstract

Nonerosive reflux disease (NERD) is a highly prevalent phenotype of the gastroesophageal reflux disease. In this study, we developed a novel murine model of NERD in mice with microscopic inflammation and impairment in the epithelial esophageal barrier. Female Swiss mice were subjected to the following surgical procedure: the transitional region between the forestomach and the glandular portion of the stomach was ligated, and a nontoxic ring was placed around the duodenum near the pylorus. The control group underwent sham surgery. The animals were euthanized at 1, 3, 7, and 14 days after surgery. Survival and body weight were monitored daily. Esophageal wet weight, macroscopic lesion, histopathological alterations, myeloperoxidase (MPO) activity, cytokine levels, transepithelial electrical resistance (TEER), and mucosal permeability were evaluated. The survival rate was 78% at 14 days, with mild loss in body weight. Surgery did not induce erosive esophagitis but instead induced microscopic inflammation and increased esophageal wet weight, IL-6, keratinocyte-derived cytokine (KC) levels, and MPO activity with maximal peak between 3 and 7 days and resolution at 14 days postsurgery. Epithelial esophageal barrier was evaluated in operated mice at 7 and 14 days postsurgery; a decrease in TEER and increase in the esophageal epithelial permeability were observed compared with the sham-operated group. In addition, the inhibition of acid secretion with omeprazole significantly prevented the esophageal inflammation and impairment of barrier function at 7 days postsurgery. Thus we established a novel experimental model of NERD in mice, which can contribute to understanding the pathophysiological events associated with NERD. In this study, we standardized an experimental model of nonerosive reflux disease (NERD) in mice. This model involves an acute inflammatory response followed by impaired esophageal mucosal integrity, even in the absence of inflammation. Thus this model can serve for evaluation of pathophysiological aspects of NERD and open new perspectives for therapeutic strategies for patients with this disorder.

Role of TRPV1 receptor in inflammation and impairment of esophageal mucosal integrity in a murine model of nonerosive reflux disease

“…Recently, we established a murine model of NERD that reproduced important aspects of NERD pathophysiology, such as microscopic inflammation without erosions, which are associated with esophageal mucosal integrity impairment. 4 In accordance with previous reports, 3,5 we demonstrated that gastric secretion inhibition by omeprazole, at least partially, decreases inflammation and mucosal integrity impairment in our NERD model. 4 The mechanism underlying acid-induced mucosal changes in NERD is not completely clear.…”

“…The slides were analyzed by light microscopy by a pathologist (P.M.G.S.) without knowledge of the treatments, according to criteria described previously . Briefly, basal cell layer hyperplasia (scores, 0–2), intraepithelial polymorphonuclear cells (scores, 0–2), erosions (scores, 0–1), edema (scores, 0–4), and polymorphonuclear cells in the lamina propria (scores, 0–3) were examined.…”

“…For this experiment, the esophagus was dissected, stripped of its muscle layers, and dissected in a plate containing Krebs‐Henseleit bicarbonate buffer (KHBB; pH 7.4). Esophageal mucosa sections were mounted on an adapted Ussing chamber (Mussler Scientific Instruments, Aachen, Germany) with an exposure area of 0.017 cm 2 . TEER and permeability to fluorescein were measured in the system with KHBB equilibrated at 37°C and continuously gassed with carbogen (95% O 2 and 5% CO 2 ).…”

“…Then, the tissues were mounted in the chamber and a stable TEER baseline was obtained from an equilibrated electrical system (30 minutes). Next, the recording was paused, and KHBB solution in each esophageal mucosa was replaced with an acidic solution (pH 0.5, containing 1 mg/mL pepsin and 2 mM taurodeoxycholic acid [TDCA]) as previously described . The tissues were exposed to the acidic solution for 60 minutes, and the TEER was continuously measured .…”

“…Next, the recording was paused, and KHBB solution in each esophageal mucosa was replaced with an acidic solution (pH 0.5, containing 1 mg/mL pepsin and 2 mM taurodeoxycholic acid [TDCA]) as previously described. 4 The tissues were exposed to the acidic solution for 60 minutes, and the TEER was continuously measured. 19 Results are expressed as the percentage change (%) in TEER from baseline at 10, 30, and 60 minutes post acid exposure.…”