Excessive Interleukin 18 Relate the Aggravation of Indomethacin-Induced Intestinal Ulcerogenic Lesions in Adjuvant-Induced Arthritis Rat.

It is well known that rheumatoid arthritis patients taking nonsteroidal anti-inflammatory drugs (NSAIDs) are more susceptible to NSAIDs-induced gastroenteropathy in comparison with other patients. In this study we demonstrate that expression levels of interleukin (IL)-18 are related to aggravation of intestinal ulcerogenic lesions in adjuvant-induced arthritis (AA) rats following oral administration of indomethacin. AA rats were administered oral indomethacin (40 mg/kg) and killed under deep isoflurane anesthesia after 24 h. The small intestinal mucosa was then examined. Oral administration of indomethacin caused hemorrhagic lesions in the small intestinal mucosa of AA rats, and the lesion score of AA rats 24 h after indomethacin treatment was approximately 5.6-fold higher than for normal rats administered indomethacin. IL-18 expression in the small intestinal mucosa of AA rats administered indomethacin was also higher in comparison with normal rats receiving indomethacin. In addition, interferon-γ and nitric oxide levels in the small intestinal mucosa of AA rats were increased following oral administration of indomethacin. It is possible that IL-18 expression in AA rats renders the small intestinal mucosa more sensitive to indomethacin, and that IL-18 may play a role in aggravating intestinal ulcerogenic lesions in AA rats treated with this drug.