Metalloproteases and inhibitors in arthritic diseases

Controlling degradation of the extracellular matrix is crucial in arthritic diseases such as osteoarthritis (OA) and rheumatoid arthritis (RA), as conventional treatments do not positively affect the structural properties of the articular tissues. Metalloproteases, a family of zinc-dependent enzymes, and more specifically the matrix metalloproteases (MMPs), play a premier role in joint articular tissue degeneration. Additional enzymes of the metalloprotease family, such as the membrane-type metalloproteases (MT-MMPs) and the adamalysins that include the ADAMs and the ADAMTS families, have also been found to be involved in these disease processes. At present, therapeutic intervention based on the inhibition of metalloproteases, and more particularly of the MMPs, is under intensive investigation, and several MMP inhibitors are in clinical development. Currently, MMP inhibitors are exemplified by several chemical classes: hydroxamic acids, carboxylic acids and thiols. One key issue in the clinical development of MMP inhibitors relates to whether broad-spectrum inhibitors active against a range of different enzymes or selective inhibitors targeted against a single enzyme or particular subset of the MMPs represents the optimal strategy. In this chapter, we address the different metalloprotease enzymes and sub-families and their implication in arthritic diseases. Furthermore, we assess physiological and chemical metalloprotease inhibitors, and for the latter, the current inhibitory classes of compounds being studied.