Anti-angiogenic effect of total saponins of Rhizoma Dioscorea nipponica on collagen induced-arthritis in rats.

Rheumatoid arthritis (RA) is a common chronic autoimmune and incurable disease. The aim of the present study was to investigate the therapeutic effect and mechanism of the total saponins of Rhizoma Dioscorea nipponica (TSRDN) in RA. A collagen induced-arthritis (CIA) rat model was established. CIA rats were randomly divided into three groups and lavaged with an equal volume of solvent (CIA group), TSRDN (25 mg/kg/day, RDN group) and tripterygium (TP; 12 mg/kg/day, TP group) for 21 days, respectively. Normal rats served as a control group. Hematoxylin-eosin (HE) staining was used to observe the histopathological injury of synovial tissues. The level of CD31, which used for marking and counting, micro vessel density (MVD) and the expression levels of vascular endothelial growth factor (VEGF) and signal transducer and activator of transcription 3 (STAT3) were detected by immunohistochemical analysis. Additionally, the DNA-binding activity of nuclear factor-κB (NF-κB) was determined using an ELISA kit. HE staining showed obvious synovial hyperplasia, inflammatory cell infiltration, pannus formation, cartilage and bone erosion in the CIA group rats. In addition, compared with control group, the level of MVD, the expression of VEGF and STAT3, and the DNA-binding activity of NF-κB were all increased in CIA group rat synovial tissue (all P<0.01); however, TSRDN or tripterygium were able to inhibit these changes (all P<0.01). It was speculated that TSRDN may prevent angiogenesis by inhibiting the expression of STAT3 and the DNA-binding activity of NF-κB p65, thereby potentially improving CIA.