Besides the mnnomcric mammalian 95 kDa progelatinase, two additional forms, ~1 disulfide-bridged 220 kDa dinxr and a 125 kDn form were isolated from human PMN Icukocytes. The I25 kDa progelatinase was identified as a covalcntly linked, disul!!de-bridged hetcrodimer formed of the monomer with a 2s kDa protein. This 25 kDa protein was isolntcd from pclatinase bound to the atIinity support of gelatin-Scpharosc and eluted by DTE-containing bulli3r. The amino acid sequence of tryptic peptides of this protein rcvenled homology with an c+-microglobulin-related protein from rats, a protein so far unknown in humans.

Interleukin-8 is critically involved in the process of parturition in humans. Interleukin-8 concentrations in the myometrium, decidua, and membranes correlated strongly with the observed MMP-8 and MMP-9 concentrations.

Human polymorphonuclear-leucocyte collagenase (M(r) 64,000) shows autoproteolytic degradation to two major fragments of M(r) 40,000 and M(r) 27,000. N-terminal sequence data and investigation of the substrate specificity of the fragments demonstrate that the M(r)-40,000 fragment corresponds to the catalytic domain, whereas the M(r0-27,000 fragment shows no enzymic activity. The activity profile of the M(r)-40,000 fragment is comparable with the specificity of the intact active collagenase (M(r) 64,000), but the ability to cleave collagen was lost. The enzymic activity of this fragment can be inhibited by either tissue inhibitor of metalloproteinase (TIMP)-1 or recombinant TIMP-2 in a 1:1 molar ratio. The C-terminal part of the enzyme (M(r) 27,000), important for the binding reaction with collagen substrates, is involved in collagenolysis.

The proteolytic erosion of the temporal bone is the key event in the pathognomonic course of cholesteatoma progression. The molecular mechanisms of bone resorption, endangering the ossicles, the inner ear, the facial nerve, large vessels or the brain, are not understood. Recently, a new family of proteolytic enzymes, the matrix-metalloproteinases (MMP's) has been described and identified, which seems to play a pivotal role in matrix- and bone homeostasis and inflammatory osteolytic diseases, e.g. osteoarthritis and periodontitis. These enzymes are sophisticatedly controlled by specific inhibitors and activation cascades. We investigated whether human cholesteatoma tissue expresses MMP's and MMP-inhibitors. By immunocytochemistry of cholesteatoma-cryosections, the expression of MMP-2 (72 kD collagenase), MMP-9 (92 kD collagenase), and MMP-3 (stromelysin-1) could be seen to be strictly confined to the basal and suprabasal cell layer of the cholesteatoma epithelium. The neutrophil collagenase (MMP-8) showed a more disseminated expression in the epithelium and the granulation tissue as well. The tissue inhibitor of metalloproteases, TIMP-1, could be detected only in very limited areas of the granulation tissue in a quite randomized manner. Therefore, a derailment in favor of proteolysis of the normally tightly controlled MMP-system might be postulated. The results indicate that members of the MMP-family could play an active role in the molecular mechanisms of cholesteatoma invasion into the temporal bone. This offers new insights into the pathophysiology of the disease and of potential therapeutic approaches.

Objective. To investigate the role of interleukin-6 (IL-6) and transforming growth factor pl (TGFp1) in the regulation of tissue inhibitor of metalloproteinases-1 (TIMP-1) synthesis in human articular chondrocytes.Methods. Articular cartilage was obtained from human knee joints 24 hours after death. Chondrocytes were isolated by collagenase digestion and embedded in low-gellingtemperature agarose. After stimulation by cytokines, total RNA was isolated and analyzed by Northern blotting. TIMP-1 protein levels were determined using a competitive enzyme-linked immunosorbent assay.Results. Human chondrocytes in agarose culture expressed messenger RNA (mRNA) for the IL-6 receptor (gp80) and its signal-transducing subunit gp130. In contrast to the findings in a previous study, IL-6 did not stimulate TIMP-1 expression in these cells, whereas TGFPl was an important inducer of TIMP-1 mRNA and protein synthesis.Conclusion. Our findings suggest that TGFBl