Jiménez P et al. (2005) Free radicals and antioxidant systems in reflux esophagitis and Barrett's esophagus. World J Gastroenterol 11: 2697–2703

The severity of Barrett's esophagus and reflux esophagitis is not determined solely by acid exposure. Studies suggest an involvement of free radicals in the associated damage to the esophageal mucosa but the protective role of antioxidant defense mechanisms in such reflux diseases remains unclear. A recent study by Jiménez and colleagues thus investigated the profile and balance between free radicals and antioxidant systems in Barrett's esophagus and esophagitis.

In this study, esophageal biopsies were taken from 101 consecutive patients with gastroesophageal reflux disease (GERD) attending the Endoscopy Unit of the University Hospital of Zaragoza, and from 28 controls with no clinical symptoms of GERD. Levels of reactive oxygen and nitrogen species were then analyzed and antioxidant status determined.

The results demonstrated that, compared with controls, patients with erosive esophagitis and Barrett's esophagus had significantly higher superoxide anion levels, and the generation of peroxynitrate was greater in Barrett's esophagus compared with esophagitis patients and controls. The activity of superoxide dismutase (SOD) antioxidant was decreased and that of glutathione and catalase increased in GERD patients compared with controls. To determine the mechanism by which SOD levels were decreased, Cu,ZnSOD and MnSOD protein expression was evaluated. Both were found to increase with lesion severity and to be highest in patients with Barrett's esophagus.

The authors concluded that “...a decrease in SOD antioxidant activity leading to increased mucosal levels of superoxide anion and peroxynitrate radicals may contribute to the development of esophageal damage and Barrett's esophagus in patients with GERD.” It was thus suggested that SOD administration might be implicated as a therapeutic target to treat such conditions.