Involvement of interleukin 18 in indomethacin-induced lesions of the gastric mucosa in adjuvant-induced arthritis rat

It is well known that nonsteroidal anti-inflammatory drugs (NSAIDs) have significant side effects, such as gastroenteropathy, and rheumatoid arthritis patients taking NSAIDs are more susceptible to NSAIDs-induced gastric lesions in comparison with other patients. The pathogenic mechanism of these lesions is not fully understood. We demonstrate whether interleukin 18 (IL-18) expression relate the aggravation of gastric lesion in adjuvant-induced arthritis (AA) rats following the oral administration of indomethacin. Arthritis was induced by injecting 50 μl of a suspension of 10 mg/ml heat-killed butyricum (Mycobacterium butyricum) in Bayol F oil into the plantar region of the right hind foot and tail of Dark Agouti rats resulting in an arthritis incidence of 100%. Two weeks after injection, the rats were administered indomethacin (40 mg/kg) orally, and were killed under deep ether anesthesia 6 h later. The gastric mucosa was then examined. Oral administration of indomethacin caused hemorrhagic lesions in the gastric mucosa of AA rats, and the lesion score for AA rats following indomethacin treatment was significantly higher than for normal rats administered indomethacin. The expression of the IL-18 mRNA and mature IL-18 protein in the gastric mucosa of AA rats administered indomethacin were also higher in comparison with normal rats receiving indomethacin. In addition, interferon-γ and nitric oxide levels in the gastric mucosa of AA rats were increased by the oral administration of indomethacin. It is possible that IL-18 expression in AA rats is more sensitive to indomethacin, and the IL-18 may play a role in the aggravation of gastric lesions in AA rats treated with indomethacin.