Beneficial effects of rosmarinic acid on suppression of collagen induced arthritis.

OBJECTIVE

To assess the therapeutic potential of rosmarinic acid (RosA) in an inflammatory autoimmune arthritis model.

METHODS

Collagen induced arthritis is established in male DBA/1 mice. Mice were administered daily with 50 mg/kg/day of RosA for 15 days from Day 21 post-immunization and inspected daily to determine the progression of arthritis. After termination of injection, affected hindpaws were subjected to histopathological analyses and immunohistochemical assays for cyclooxygenase-2 (COX-2) expression.

RESULTS

Repeated administration of RosA dramatically reduced the arthritic index and number of affected paws. Histopathologic observations closely paralleled clinical data, showing that RosA treated mice retained nearly normal architecture of synovial tissues, whereas control mice exhibited severe synovitis. Synovial tissues from RosA treated mice exhibited remarkably reduced frequency of COX-2-expressing cells, compared to those from untreated mice.

CONCLUSION

RosA suppressed synovitis in a murine collagen induced arthritis model; this effect may be beneficial for treatment of rheumatoid arthritis in clinical settings.