IL17RA and arthritic joint disease: The more pronounced difference in cartilage and bone erosions between the wild-type and the Il17ra−/− group compared to the relatively small difference in clinical signs, particularly in the first 10 days of arthritis, however, suggests that the marked protection of Il17ra−/− mice from bone and cartilage erosions may be the result of a dual effect of reduced inflammatory mediator production and anti-proliferative effects from lack of IL-17RA signaling.