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Co-operation between plasmin and elastase in elastin degradation by intact murine macrophages.

ABSTRACT: Intact, thioglycollate-stimulated murine macrophages cultured on an insoluble [3H]-elastin substratum progressively hydrolysed the elastin. Cell lysates had little activity. We compared the effect of various proteinase inhibitors on elastinolysis by either live cells or cell-free, elastase-rich conditioned medium. Only known inhibitors of macrophage elastase blocked the activity of elastase-rich cell-conditioned medium whereas inhibitors of cathepsin B also suppressed intact cell activity. Serum proteinase inhibitors blocked cell-derived soluble elastase activity but not intact cell elastolytic activity. We also observed that plasminogen added to the cell cultures markedly increased elastinolysis by live macrophages or cell-free elastase-rich medium. Purified plasmin alone had no measurable effect on native elastin. Additional experiments indicated that the plasmin enhancement was due to elastin-dependent activation of latent macrophage elastase. These results indicate that live macrophage elastinolysis is a co-operative process involving multiple proteinases, especially a cysteine proteinase(s) and elastase. Plasmin may be a physiological activator of latent macrophage elastase.

SUBMITTER: Chapman HA

PROVIDER: S-EPMC1144235 | biostudies-other | 1984 Sep

REPOSITORIES: biostudies-other

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Macrophage elastase kills bacteria within murine macrophages.

Project description:Macrophages are aptly positioned to function as the primary line of defence against invading pathogens in many organs, including the lung and peritoneum. Their ability to phagocytose and clear microorganisms has been well documented. Macrophages possess several substances with which they can kill bacteria, including reactive oxygen species, nitric oxide, and antimicrobial proteins. We proposed that macrophage-derived proteinases may contribute to the antimicrobial properties of macrophages. Macrophage elastase (also known as matrix metalloproteinase 12 or MMP12) is an enzyme predominantly expressed in mature tissue macrophages and is implicated in several disease processes, including emphysema. Physiological functions for MMP12 have not been described. Here we show that Mmp12(-/-) mice exhibit impaired bacterial clearance and increased mortality when challenged with both gram-negative and gram-positive bacteria at macrophage-rich portals of entry, such as the peritoneum and lung. Intracellular stores of MMP12 are mobilized to macrophage phagolysosomes after the ingestion of bacterial pathogens. Once inside phagolysosomes, MMP12 adheres to bacterial cell walls where it disrupts cellular membranes resulting in bacterial death. The antimicrobial properties of MMP12 do not reside within its catalytic domain, but rather within the carboxy-terminal domain. This domain contains a unique four amino acid sequence on an exposed beta loop of the protein that is required for the observed antimicrobial activity. The present study represents, to our knowledge, the first report of direct antimicrobial activity by a matrix metallopeptidase, and describes a new antimicrobial peptide that is sequentially and structurally unique in nature.

| S-EPMC2885871 | biostudies-literature

Removal of adsorbed elastase from partially digested elastin.

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| S-EPMC1172896 | biostudies-other

Mechanical forces regulate elastase activity and binding site availability in lung elastin.

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Serological assessment of neutrophil elastase activity on elastin during lung ECM remodeling.

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Multiphoton Imaging of Collagen, Elastin, and Calcification in Intact Soft-Tissue Samples.

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Elastin degradation by cathepsin V requires two exosites.

Project description:Cathepsin V is a highly effective elastase and has been implicated in physiological and pathological extracellular matrix degradation. However, its mechanism of action remains elusive. Whereas human cathepsin V exhibits a potent elastolytic activity, the structurally homologous cathepsin L, which shares a 78% amino acid sequence, has only a minimal proteolytic activity toward insoluble elastin. This suggests that there are distinct structural domains that play an important role in elastinolysis. In this study, a total of 11 chimeras of cathepsins V and L were generated to identify elastin-binding domains in cathepsin V. Evaluation of these chimeras revealed two exosites contributing to the elastolytic activity of cathepsin V that are distant from the active cleft of the protease and are located in surface loop regions. Replacement of exosite 1 or 2 with analogous residues from cathepsin L led to a 75 and 43% loss in the elastolytic activity, respectively. Replacement of both exosites yielded a non-elastase variant similar to that of cathepsin L. Identification of these exosites may contribute to the design of inhibitors that will only affect the elastolytic activity of cysteine cathepsins without interfering with other physiological protease functions.

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| S-EPMC3537671 | biostudies-literature

Interaction between the elastin peptide VGVAPG and human elastin binding protein.

Project description:The elastin binding protein (EBP), a spliced variant of lysosomal β-galactosidase, is the primary receptor of elastin peptides that have been linked to emphysema, aneurysm and cancer progression. The sequences recognized by EBP share the XGXXPG consensus pattern found in numerous matrix proteins, notably in elastin where the VGVAPG motif is repeated. To delineate the elastin binding site of human EBP, we built a homology model of this protein and docked VGVAPG on its surface. Analysis of this model suggested that Gln-97 and Asp-98 were required for interaction with VGVAPG because they contribute to the definition of a pocket thought to represent the elastin binding site of EBP. Additionally, we proposed that Leu-103, Arg-107, and Glu-137 were essential residues because they could interact with VGVAPG itself. Site-directed mutagenesis experiments at these key positions validated our model. This work therefore provides the first structural data concerning the interaction of the VGVAPG with its cognate receptor. The present structural data should now allow the development of EBP-specific antagonists.

| S-EPMC3543015 | biostudies-literature

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