Preparation and analysis of active rat model of rheumatoid arthritis with features of TCM toxic heat-stasis painful obstruction

Objective: To establish a collagen type II-induced rat model of rheumatoid arthritis (RA) presenting characteristics of the human form of the traditional Chinese syndrome pattern of toxic heat-stasis painful obstruction (bi zheng; arthromyodynia) as well as pathologic features of active RA. The Chinese herbal medicine Tengmei decoction was used to validate the animal model. Methods: Ninety specific pathogen free Sprague-Dawley rats were randomly divided into a normal group of 6 rats and a model group of 84 rats. To establish the rat model of collagen-induced arthritis (CIA), bovine type II collagen in complete Freund's adjuvant was injected into the model group rats as a priming dose (Day 0) and boosting dose (Day 9). Changes in arthritic index (AI) scores, including limb swelling, were monitored. Thereafter, 24 successfully-established CIA rats were randomly assigned to 4 groups with 6 animals each: model, positive control drug, high-dose traditional Chinese herbal medicine, and traditional Chinese herbal medicine. A blank control group of 6 rats was included. After 12 weeks of intervention with Tengmei decoction, articular synovial tissue and serum specimens were collected to detect interleukin-2 (IL-2) and IL-17 transcription and protein expression levels. Results: Days 0 through 9, the anterior–posterior and lateral diameters of the limbs in model group rats did not differ significantly when compared to the normal control group (P > .05). On day 16, anterior–posterior, lateral diameters, and footpad thicknesses of both hind limbs in the model group were higher than those of the normal control group (P < .01, P < .05). Total AI, AI of both hind limbs between Days 11 and 16 were significantly higher than those of the normal control group (P < .01). Real-time reverse transcription polymerase chain reaction analyses of rat joint tissues indicated that compared to the normal control group, levels of mRNA transcription of IL-2 and IL-17 were significantly upregulated (P < .01) in the model group. Compared with the model group, levels of mRNA transcription of the aforementioned inflammatory cytokines were significantly downregulated in the positive control drug and traditional Chinese medicine treatment groups (P < .01). Results of ELISA analyses indicated that compared with the normal control group, levels of protein expression of cytokines IL-2, IL-17 were significantly upregulated (P < .01) in the model group. Compared with the model group, levels of protein expression of the aforementioned inflammatory cytokines were significantly downregulated in the positive control drug and traditional Chinese medicine treatment groups (P < .01). Conclusion: The CIA model established in this study presents both active RA pathologic features and characteristics of the symptoms of toxic heat-stasis painful obstruction 12 weeks after successful establishment of an animal model. In addition, this study may be a valuable reference for development of animal studies with combined Eastern and Western medicines in dialectics and identification of diseases