Astilbin suppresses collagen-induced arthritis via the dysfunction of lymphocytes.

To examine the therapeutic effects of astilbin, a flavanoid isolated from Rhizoma Smilacis Glabrae, on arthritis and to compare it with cyclosporine A (CsA). Type II collagen-induced arthritis in mice and its in vitro assays for proliferation, matrix metalloproteinase (MMP) and NO production were performed. Astilbin dose-dependently inhibited the footpad swelling, arthritic incidence, and clinical scores without influencing the body weights, while CsA showed strong inhibition with a significant weight loss. Histological examination revealed marked inflammatory damage in arthritic mice including joint swelling, synovial hyperplasia, and cartilage destruction. Against these, an intact joint structure was maintained in astilbin-treated or CsA-treated mice. In isolated spleen cells from arthritic mice, increased potentials in proliferation, NO production, and MMP-2 and 9 activities were suppressed dose-dependently by the oral administration of astilbin. Additionally, astilbin showed neither any cytotoxicity to nor influence on Con A-induced proliferation of spleen cells from naive mice, while CsA showed a dose-dependent cytotoxicity and inhibition of the proliferation. Astilbin may act as an efficient therapeutic agent for arthritis like CsA but with less toxicity. Its mechanism includes a selective suppression on lymphocyte functions via reducing MMP and NO production.