Cytokine-induced Neutrophil Accumulation in the Pathogenesis of Acute Reflux Esophagitis in Rats

Although recent reports indicate an increasing incidence of patients with reflux esophagitis, its pathomechanism remains unclear. Cytokines and neutrophils, the latter of which produce reactive oxygen species (ROS), have been implicated in the formation of gastrointestinal diseases. This study investigated the roles of neutrophils, ROS, and cytokines in the pathogenesis of experimental reflux esophagitis. Esophagitis was induced in male Wistar rats by ligation at both the limiting ridge of the stomach and lower portion of the duodenum. The esophagus was then removed, and the lesion index, wet weight, thiobarbituric acid-reactive substances (an index of lipid peroxidation), myeloperoxidase activity (an index of neutrophil accumulation), tumor necrosis factor-alpha (TNF-alpha), and cytokine-induced neutrophil chemoattractant (CINC)-1 in the esophageal mucosa were estimated, and a histological study (hematoxylin-and-eosin staining) was performed. The mRNA expression of TNF-alpha and CINC-1 was analyzed. Anti-neutrophil serum (ANS) was injected intraperitoneally prior to the induction of esophagitis, and inflammatory markers were estimated as described above. The values of all markers increased, and the histological study revealed neutrophil infiltration and edema in mucosa and submucosa at both 12 and 18 h after induction. However, the mRNA expression of both cytokines was observed earlier at 3 and 6 h after induction. ANS inhibited the increases in all inflammatory markers. These results indicate that ROS and lipid peroxidation mainly derived from neutrophils, which are stimulated and mobilized by TNF-alpha and CINC-1, are implicated in the pathogenesis of esophageal inflammation induced by the reflux of gastroduodenal contents.