Will o' the wisp: CCN4 as a novel molecular target in osteoarthritis.

Osteoarthritis (OA), or degenerative arthritis, is characterized by mechanical stress-induced changes in cartilage and bone. OA is a leading cause of chronic disability in North America and Europe. A recent study written by Blom and colleagues (Arthritis and Rheumatism 2009; 60:501-12) showed that elevated wnt signaling was observed in experimental OA as well as in patient samples. The authors found that the known wnt target WISP-1 (CCN4) was also overexpressed; CCN4 was sufficient to recapitulate an OA phenotype in vitro and in vivo, suggesting that CCN4 may be a novel target for drug intervention in OA. This commentary summarizes these exciting findings.