Matrix metalloproteinases (MMPs) compose a family of zinc-and calcium-dependent proteolytic enzymes responsible for extracellular matrix (ECM) remodeling and the regulation of the trans-ECM migration of leukocytes, an important step in inflammatory processes as well as infectious diseases. MMPs are functionally classified according to their relative substrate specificities but have been shown to overlap. Collagenases (MMP-1, -8, and -13) degrade type I collagen, whereas gelatinases A and B (MMP-2 and -9, respectively) degrade denatured type I (gelatin) and type IV collagens, a major component of the basement membrane. Collagenases are produced by many cell types including lymphocytes, granulocytes, astrocytes, and activated macrophages (10, 18).MMP secretion takes place under tight regulatory mechanisms including transcriptional controls in addition to their release as proenzymes, requiring activation by specific proteases and cytokines present in the milieu (2,3,16). Also, the postactivation of MMPs is controlled by metalloproteinase tissue inhibitors (tissue inhibitor of MMP [TIMP]), a family of specific inhibitors, that bind to MMPs in a stoichiometric ratio.