Characterization of and osteoarthritis susceptibility in ADAMTS‐4–knockout mice

Abstract

Objective. To determine the importance of the enzymatic activity of ADAMTS-4 in normal growth and development and to evaluate the role of ADAMTS-4 in the progression of osteoarthritis (OA).Methods. We generated catalytic domain-deleted ADAMTS-4-transgenic mice and performed extensive gross and histologic analyses of various organs. The mice were challenged by surgical induction of joint instability leading to OA, to determine the importance of the enzymatic activity of ADAMTS-4 in the progression of the disease. The response of wild-type (WT) and ADAMTS-4-knockout (ADAMTS-4-KO) articular cartilage to interleukin-1 and retinoic acid challenge in vitro was also evaluated.Results. ADAMTS-4-KO mice up to 1 year of age exhibited no gross or histologic abnormalities in 36 tissue sites examined. Despite evidence of ADAMTS-4 expression and activity in growth plates of WT mice, catalytic silencing of this proteinase caused no abnormalities in skeletal development, growth, or remodeling. There was no effect of ADAMTS-4 knockout on the progression or severity of OA 4 weeks or 8 weeks after surgical induction of joint instability. Enzymatic cleavage of aggrecan at the TEGE 373-374 ARGS site was clearly evident after exposure of articular cartilage from ADAMTS-4-KO mice to inflammatory cytokines. Conclusion. Although expression of the ADAMTS-4 gene has been found in many tissuesthroughout the body, deletion of enzymatic activity did not appear to have any effect on normal growth and physiology. Our study provides evidence that ADAMTS-4 is the primary aggrecanase in murine growth plates; however, deletion of its enzymatic activity did not affect normal long bone remodeling. Our results also lead to the hypothesis that, in the mouse, ADAMTS-4 is not the primary enzyme responsible for aggrecan degradation at the TEGE 373-374 ARGS site. The elucidation of the relative importance of ADAMTS-4 in the pathologic process of human OA will require examination of human OA tissues and evidence of disease modification in patients following therapeutic intervention.

Accelerated development of aging‐associated and instability‐induced osteoarthritis in osteopontin‐deficient mice

“…For the induction of cartilage degradation, the explants were then washed 3 times and cultured for an additional 72 hours in serum-free DMEM. Conditioned medium was collected at the end of the culture period (32,33).…”

Proteomic characterization of mouse cartilage degradation in vitro

“…Indeed, experiments in catabolically stimulated mouse cartilage explants were found to be predictive of protection against cartilage degeneration in several ADAMTS-deficient mice (9,(12)(13)(14). Although proteinases typically cleave multiple substrates within tissue, fragmentation studies in mouse cartilage explants have been restricted almost exclusively to aggrecan degradation (12,13,15).…”

The role of proteases in pathologies of the synovial joint

“…In a model of inflammatory arthritis, ADAMTS-5, but not ADAMTS-4, knockout mice were protected against aggrecan loss (Stanton et al, 2005). Furthermore, aggrecanase activity was inducible in articular cartilage explants from wild-type and ADAMTS-4 knockout mice but not from ADAMTS-5 knockout littermates (Glasson et al, 2004(Glasson et al, , 2005Stanton et al, 2005). Together these studies suggest that, at least in these mouse models, ADAMTS-5 is primarily responsible for the increased aggrecanase activity and subsequent development of arthritis.…”

“…domain knockouts of each gene (Glasson et al, 2004(Glasson et al, , 2005Malfait et al, 2002). Both ADAMTS-4 and -5 knockout mice were phenotypically normal and indistinguishable from wild-type littermates, indicating that each enzyme was dispensable for normal development (Glasson et al, 2004(Glasson et al, , 2005Stanton et al, 2005).…”

“…Both ADAMTS-4 and -5 knockout mice were phenotypically normal and indistinguishable from wild-type littermates, indicating that each enzyme was dispensable for normal development (Glasson et al, 2004(Glasson et al, , 2005Stanton et al, 2005). In a surgically induced OA model there was a major reduction in the severity of induced OA in ADAMTS-5 knockout mice, but no difference in progression or severity in ADAMTS-4 knockout mice (Glasson et al, 2004(Glasson et al, , 2005. In a model of inflammatory arthritis, ADAMTS-5, but not ADAMTS-4, knockout mice were protected against aggrecan loss (Stanton et al, 2005).…”