Phenotypic characterization of type II collagen-induced arthritis in Wistar rats

The aim of the present study was to determine a more specific, efficient and simple method for the induction of collagen-induced arthritis (CIA) in rats. Different strains of rats were injected at the base of the tail with bovine type II collagen (CII) emulsified in incomplete Freund's adjuvant (IFA). The onset and severity of arthritis were evaluated by clinical assessment. The established CIA model was analyzed using a comprehensive examination of clinical, hematological, histological and radiological parameters. The results demonstrated that Wistar rats were the most susceptible strain to CIA followed by Wistar Furth rats, with Sprague Dawley rats being the least susceptible. Following primary and booster immunization, female Wistar rats developed severe arthritis, with an incidence of >83% and low variability in clinical signs. The development of arthritis was accompanied by a significantly elevated erythrocyte sedimentation rate compared with that in the control rats. The radiographic examination revealed bone matrix resorption, considerable soft tissue swelling, periosteal new bone formation and bone erosion in the arthritic joints of the CIA rats. Histopathologically, the synovial joints of CIA rats were characterized by synovial hyperplasia, pannus formation, marked cellular infiltration, bone and cartilage erosion and narrowing of the joint space. The administration of an intradermal injection of only 200 µg bovine CII emulsified in IFA at the base of the tail therefore leads to the successful development of a CIA rat model. This well-characterized CIA rat model could be specifically used to study the pathophysiology of human rheumatoid arthritis as well as to test and develop anti-arthritic agents for humans.