Suppressive effect of hochu-ekki-to on collagen induced arthritis in DBA1J mice.

Objective: To investigate the effect of hochu-ekki-to (HET) decoction on the development of collagen-induced arthritis (CIA) in mice.

Methods: CIA was induced in male DBA/IJ mice by immunization with 2 injections of bovine type II collagen (CII). HET was orally administered at different doses and with different schedules. The incidence of arthritis, arthritis index, levels of anti-CII antibody, interleukin 6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha) and lymphocyte subsets were examined.

Results: HET caused suppression of CIA development in a dose dependent fashion and exerted a suppressive effect on CIA when administered from the first CII immunization or from the onset of CIA, but not when administered for 2 weeks before CII immunization. HET inhibited the production of specific anti-CII antibody, IL-6, and TNF-alpha, and tended to normalize the proportions of cells in lymphocyte subsets.

Conclusion: HET suppresses the development of CIA, and HET redistributes the population of lymphocytes in lymph node and blood and inhibits IL-6 and TNF-alpha secretion in CIA mice.