THE EFFECT OF DEXAMETHASONE ON THE EXPRESSION OF ACTIVATED NF-KAPPA-BIN ADJUVANT ARTHRITIS

The transcription factor NF-kappa B plays a significant role in inflam matory diseases. In this study we have investigated the expression of activated NF-kappa B p65 subunit in the rat adjuvant arthritis model i n a 28-day time-course experiment using immunohistochemistry. The expr ession of p65 was detected in the synovial lining layer and around the blood vessels in the inflamed synovium as early as Day 3 post-adjuvan t injection. The cells that expressed p65 in the synovial lining were thought to be macrophage-like synoviocytes. The expression was stronge r in the injected hindpaw than that in the noninjected hindpaw. Dexame thasone treatment at 1 mg/kg po (Days 0-20) suppressed both the hindpa w edema and increase in p65 expression. Withdrawal of the treatment ca used increases in both p65 expression and paw volume. Together these s uggest that activated NF-kappa B was specifically expressed in the art hritic synovium and may play a significant role in the development of arthritis. (C) 1997 Academic Press.