Expression and Activities of Matrix Metalloproteinases under Oscillatory Shear in IL-1-Stimulated Synovial Cells

Matrix metalloproteinases (MMPs) are known to play a critical role in tissue disintegration, and an elevated level of MMPs is observed in synovium and synovial fluid of joints with rheumatoid arthritis. During joint movement, synovial tissue receives various mechanical stimuli, but effects of mechanical challenges on regulation of MMPs in rheumatic synovium are poorly understood. Focusing on cellular responses to oscillatory fluid shear in human synovial cells, we determined the expression of MMP-1 and MMP-13 by polymerase chain reaction and immunoblotting as well as proteolytic activities of total MMPs by a fibril degradation assay and zymography. The results revealed that ~0.5 dyn/cm 2 oscillatory shear at 1 Hz not only reduced an mRNA level and a protein level of MMP-1 and MMP-13, but it also decreased collagenase and gelatinase activities of total MMPs. Furthermore, the induction of the MMP expression and activities by interleukin-1 was suppressed by the oscillatory shear. Interestingly, the oscillatory shear upregulated the mRNA expression of TIMP-1 and TIMP-2. Our results support a potential role of oscillatory shear in regulating expression and activities of MMPs in the presence and the absence of proinflammatory cytokine

The Effect of Synovial Fluid Enzymes on the Biodegradability of Collagen and Fibrin Clots

Recently there has been a great deal of interest in the use of biomaterials to stimulate wound healing. This is largely due to their ability to centralize high concentrations of compounds known to promote wound healing at a needed location. Joints present a unique challenge to using scaffolds because of the presence of enzymes in synovial fluid which are known to degrade materials that would be stable in other parts of the body. The hypothesis of this study was that atelocollagen scaffolds would have greater resistance to enzymatic degradation than scaffolds made of gelatin, fibrin and whole blood. To test this hypothesis, collagen and fibrin-based scaffolds were placed in matrix metallopeptidase-1 (MMP-1), elastase, and plasmin solutions at physiologic concentrations, and the degradation of each scaffold was measured at varying time points. The atelocollagen scaffolds had a significantly greater resistance to degradation by MMP-1, elastase and plasmin over the fibrin based scaffolds. The results suggest that atelocollagen-based scaffolds may provide some protection against premature degradation by synovial fluid enzymes over fibrin-based matrices

La convertase de proprotéines furine et son implication dans le développement de l'arthrite expérimentale chez le rat

La polyarthrite rhumatoïde est une maladie immunitaire touchant environ 1% de la population mondiale. La furine, une convertase de proprotéines, est responsable de la maturation de plusieurs substrats impliqués dans la pathologie, dont le TGF-[bêta]1, le PDGF AB, la MMP-3 et la MT1-MMP (active la MMP-2). Cette convertase est impliquée dans la maturation de la TACE, l'enzyme de conversion du TNF[alpha], et pourrait être impliquée dans la maturation des agrécanases qui participent à la dégradation du cartilage. Le nombre élevé de substrats de la furine connus ou putatifs impliqués dans la polyarthrite permet de supposer que cette convertase puisse jouer un rôle majeur dans le développement de la pathologie. Afin de vérifier cette possibilité, nous avons utilisé un adénovirus (AdTR5PDX) encodant un inhibiteur puissant de la furine, l'alpha 1-antitrypsine de type Portland ([alpha indice inférieur 1]-PDX). L'ADNc de l'[alpha indice inférieur 1]-PDX a été inséré dans une cassette dicistronique contenant aussi l'ADNc du gène rapporteur de la protéine à fluorescence verte, et soumis au contrôle d'un promoteur régulé de façon négative par la doxycycline. Nous avons ensuite vérifié in vivo l'efficacité du vecteur adénoviral AdTR5PDX."--Résumé abrégé par UMI

Human matrix metalloproteinases: An ubiquitarian class of enzymes involved in several pathological processes

Human matrix metalloproteinases (MMPs) belong to the M10 family of the MA clan of endopeptidases. They are ubiquitarian enzymes, structurally characterized by an active site where a Zn(2+) atom, coordinated by three histidines, plays the catalytic role, assisted by a glutamic acid as a general base. Various MMPs display different domain composition, which is very important for macromolecular substrates recognition. Substrate specificity is very different among MMPs, being often associated to their cellular compartmentalization and/or cellular type where they are expressed. An extensive review of the different MMPs structural and functional features is integrated with their pathological role in several types of diseases, spanning from cancer to cardiovascular diseases and to neurodegeneration. It emerges a very complex and crucial role played by these enzymes in many physiological and pathological processes