TIMP-3 is a potent inhibitor of aggrecanase 1 (ADAM-TS4) and aggrecanase 2(ADAM-TS5)

The proteoglycan aggrecan is an important major component of cartilage matr ix that gives articular cartilage the ability to withstand compression, Inc reased breakdown of aggrecan is associated with the development of arthriti s and is considered to be catalyzed by aggrecanases, members of the ADAM-TS family of metalloproteinases. Four endogenous tissue inhibitors of metallo proteinases (TIMPs) regulate the activities of functional matrix metallopro teinases (MMPs), enzymes that degrade most components of connective tissue, but no endogenous factors responsible for the regulation of aggrecanases h ave been found. We show here that the N-terminal inhibitory domain of TIMP- 3, a member of the TIMP family that has functional properties distinct from other TIMPs, is a strong inhibitor of human aggrecanases 1 and 2, with K-i values in the subnanomolar range. This truncated inhibitor, which lacks th e C-terminal domain that is responsible for interactions with molecules oth er than active metalloproteinases, is produced at high yield by bacterial e xpression and folding from inclusion bodies. This provides a starting point for developing a biologically available aggrecanase inhibitor suitable for the treatment of arthritis.