[Effects of Tongbi capsule on joint lesions in rabbits with rheumatoid arthritis]

The purpose of this experiment is to observe the effects of Tongbi capsule on joint lesions in rabbit with rheumatoid arthritis induced by ovalbumin and explore the mechanism in order to provide reference for clinical application of Tongbi capsule. Rheumatoid arthritis in rabbits was induced by subcutaneous injection of emulsions of ovalbumin and Freund's complete adjuvant and intra articular injection of ovalbumin. After successful modeling, 30 New Zealand rabbits with arthritis were randomly divided into model control group, the high, medium and low dose groups of Tongbi capsule (90, 45, 22.5 mg·kg⁻¹) and prednisone group (5 mg·kg⁻¹). Another six normal rabbits were used as normal control group. After 24 hours of modeling, the rabbits in Tongbi capsule groups received intragastric (i.g.) administrations of Tongbi capsule at 90, 45, 22.5 mg·kg⁻¹·d⁻¹, and the rabbits of prednisone group received i.g. administrations of prednisone at 5 mg·kg⁻¹·d⁻¹ for 2 weeks. The rabbits in normal and model groups received the same volume of distilled water at the same time. The swelling degree of rabbit knee joint and local skin temperature were observed daily. After two weeks of administration, pathological changes of rabbit knee joint were examined by magnetic resonance imaging (MRI); the morphological changes of articular cartilage and synovial membrane were observed by microscope; and the contents of interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-α) in serum were detected by enzyme linked immunosorbent assay (ELISA).The results showed that 24 h after modeling, the knee joints of the rabbits were swollen, with red or dark redlocal skin, and fever, elevated local skin temperature and increased diameters of knee joints. Two weeks after modeling, the swelling of rabbit knee joints was obvious in model group; the joint cavities were filled with purulent fluid; joint synovial membranes were obviously thickened, and even joint cavities were fibrotic and cartilage surfaces showed slight defect; the surface of articular cartilage was obvious fibrosis; synovial epithelial cell proliferation was obvious and accompanied by extensive inflammatory cell infiltration; the levels of IL-1 and TNF-α were significantly higher as compared with those seen in model rabbits (P<0.05, P<0.01). After 1 and 2 weeks of administration, knee joint diameters and local skin temperatures were smaller or lower than thosein model group (P<0.05, P<0.01); The lesions of joint cartilage and synovial of all rabbits in each group were less than those in model group; IL-1 and TNF-α levels in serum were also lower than those in model group (P<0.05, P<0.01). The results reveal that high and medium doses of Tongbi capsule can suppress rheumatoid arthritis induced by ovalbumin in rabbits, reduce joint swelling, inhibit synovial epithelial and fiber hyperplasia and inflammatory cell infiltration, and alleviate articular cartilage damage. The mechanism may be associated with decreasing IL-1 and TNF-α levels in serum.