Although extracellular proteolysis is a prerequisite for normal wound healing, uncontrolled proteolytic tissue destruction appears to be a pathogenic factor in non-healing wounds. The aim of our study was to compare the activities of the serine proteinases of polymorphonuclear origin, elastase and cathepsin G, and the metalloproteinases, gelatinase and collagenase, in chronic leg ulcer exudate (10 patients) and acute wound fluid (6 patients). Serine proteinase activities were low in leg ulcer exudates but very high in some but not all acute wound fluids. Total collagenase activity, measured as activity against type I collagen monitored by SDS-PAGE and densitometry, was higher in chronic leg ulcer exudate than in acute wound fluid and its degree of autoactivation was relatively high. Doxycycline inhibition studies suggested that the collagenase activity in chronic leg ulcer exudate was MMP-1 ("fibroblast-type") and not MMP-8 ("neutrophil-type"). Zymographic analysis of the gelatinolytic enzymes in acute wound fluid showed a progressive increase from the day of operation to postoperative day 5, but the degree of activity was lower than in chronic leg ulcer exudate and the low molecular mass activation products were faint. The leg ulcer gelatinase profiles were characterized by high expression of 92/82- and 72/62-kDa duplex bands and by the presence of low molecular mass activation products. Leg ulcer collagenase seems to be derived from mononuclear rather than polymorphonuclear cells, which are known to be involved in acute wound healing. In conclusion, the present study shows that gelatinase and collagenase, but not elastase and cathepsin G are found in chronic leg ulcer exudate.
The present study was carried out to characterize the patterns of expression of matrix metalloproteinases or their tissue inhibitor (TIMP-1) in normally healing, acute vs. chronic, skin wounds. In situ hybridization was performed to localize collagenase, stromelysin-1, stromelysin-2, matrilysin, urokinase plasminogen activator (uPA) and TIMP-1 mRNAs in 14 chronic venous ulcers and 10 normally healing wounds, representing different time points after wounding. Surgical wounds, made in piglets harvested at several time points, were studied as controls. Collagenase, stromelysin-1 and -2, as well as uPa, were expressed in keratinocytes in both acute and chronic wounds, while epithelial TIMP-1 mRNA was not detected in any chronic wound biopsies studied. However, TIMP-1 was expressed at the epithelial edges of both acute human and pig wounds. Our results suggest that the balance between metalloenzymes and their inhibitor TIMP-1, is disturbed, in poorly healing wounds.
The present study was carried out to characterize the patterns of expression of matrix metalloproteinases or their tissue inhibitor (TIMP-1) in normally healing, acute vs. chronic, skin wounds. In situ hybridization was performed to localize collagenase, stromelysin-1, stromelysin-2, matrilysin, urokinase plasminogen activator (uPA) and TIMP-1 mRNAs in 14 chronic venous ulcers and 10 normally healing wounds, representing different time points after wounding. Surgical wounds, made in piglets harvested at several time points, were studied as controls. Collagenase, stromelysin-1 and -2, as well as uPa, were expressed in keratinocytes in both acute and chronic wounds, while epithelial TIMP-1 mRNA was not detected in any chronic wound biopsies studied. However, TIMP-1 was expressed at the epithelial edges of both acute human and pig wounds. Our results suggest that the balance between metalloenzymes and their inhibitor TIMP-1, is disturbed, in poorly healing wounds.
These results suggest that in poorly healing venous leg ulcers, the pattern of tPA expression is altered in keratinocytes at the leading edge of the wound, and the patterns of tPA, uPA and PAI-1 expression are altered in the granulation tissue.
The effect of wound fluids collected from acute well-healing wounds and chronic nonhealing venous leg ulcers on the plasminogen activation system of keratinocyte and fibroblast cell cultures was studied in a simplified wound-healing model. Acute wound fluid was collected from donor sites of split skin grafts at different time points representing the progressive healing of the wound. Urokinase-type plasminogen activator, tissue-type plasminogen activator, urokinase-type plasminogen activator receptor, and plasminogen activator inhibitor 1 expression were studied. The methods used were immunocapture assay and immunocytochemistry. The results indicated that the later the acute wound fluid was collected, the greater the urokinase-type plasminogen activator and the lower the plasminogen inhibitor-1 level in treated cells. In contrast, the level of urokinase-type plasminogen activator receptor remained stable irrespective of wound fluid treatment. Immunostaining for urokinase-type plasminogen activator of acute wound fluid-treated cells showed a disseminated punctate pattern over the cell surface, but with chronic wound fluid, urokinase-type plasminogen activator was localized to focal contacts. Our findings support the view that in the acute wound environment the plasminogen activator system is proteolytically active and that in chronic leg ulcers urokinase-type plasminogen activator and urokinase-type plasminogen activator receptor may also be organized for cell adhesion and migration.
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