Background: The mechanisms by which Helicobacter pylori and low-dose aspirin induce gastric damage are not completely elucidated.
Aim: To evaluate the effects of low-dose aspirin on gastric damage, mucosal prostaglandin-E(2) levels and cyclooxygenase-enzyme expression in relation to the H. pylori status.
Methods: Twenty healthy volunteers (H. pylori positive, n = 10; H. pylori negative, n = 10) received aspirin 100 mg/die for 1 week. At days 0, 1, 3 and 7, gastric mucosal lesions were studied by oesophagogastroduodenoscopy and histology. COX-1 and COX-2 were determined by immunohistochemistry and reverse-transcriptase polymerase chain reaction, and mucosal prostaglandin-E(2) levels by enzyme-linked immunosorbent assay. Nine H. pylori-positive subjects repeated the protocol after H. pylori eradication.
Results: All groups developed a similar number of erosions. COX-1 and COX-2 expression, as well as mucosal prostaglandin-E(2) levels were not influenced by H. pylori status and aspirin medication. Helicobacter pylori-negative and H. pylori-eradicated subjects who developed aspirin-induced erosions had significant lower pre-treatment antral prostaglandin-E(2) levels than those without erosions (3.6 ng/microg vs. 6.3 ng/microg protein and 3.6 ng/microg vs. 6.0 ng/microg protein, respectively, P < 0.01 Mann-Whitney U-test).
Conclusions: In healthy subjects, low-dose aspirin for 1 week does neither affect cyclooxygenase expression nor mucosal prostaglandin-E(2) levels. Antral prostaglandin-E(2)-basal levels appear to be critical for development of aspirin-induced gastric damage in subjects without H. pylori infection.