Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.37 (neutrophil elastase)
 4,078 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The net balance of neutrophil elastase and its inhibitor, alpha 1-antitrypsin (alpha 1-AT), is a critical determinant of connective tissue turnover during homeostasis and in disease states. In addition to liver-derived alpha 1-AT, which translocates from blood to tissues, this elastase-alpha 1-AT balance is maintained by expression of alpha 1-AT at the local tissue level in resident mononuclear phagocytes. Our previous studies have shown that this elastase-alpha 1-AT balance is also tightly controlled at a cellular level in that addition of exogenous neutrophil elastase (serpine-type elastase) to cultured mononuclear phagocytes is associated with an increase in expression of the alpha 1-AT gene. Subsequent studies have demonstrated that this novel regulatory loop involves interaction between exogenous neutrophil elastase and endogenous alpha 1-AT inducing a structural rearrangement in the alpha 1-AT molecule and exposing highly conserved conformation-specific domain of alpha 1-AT, which can then be recognized by a specific cell surface receptor, the serpine-enzyme complex receptor. In the following study, we examined the effect of a bacterial metalloelastase, Pseudomonas aeruginosa elastase, on expression of alpha 1-AT in human mononuclear phagocytes. We show that pseudomonas elastase inactivates monocyte-derived alpha 1-AT by limited proteolysis but, in so doing, alpha 1-AT becomes recognized by the serpine-enzyme complex receptor and mediates an increase in de novo synthesis of alpha 1-AT in these cells. However, the concentrations of pseudomonas elastase needed to proteolytically inactivate alpha 1-AT in monocyte culture fluid are higher than those required for inactivation of purified plasma alpha 1-AT.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of pseudomonas elastase on human mononuclear phagocyte alpha 1-antitrypsin expression. 170 13

Emphysema in humans takes several different forms: centrilobular, panacinar, paraseptal, and airspace enlargement with fibrosis. The varying morphologic and background features of these forms of emphysema suggest that they differ in pathogenesis. Elastic fiber rupture and fraying are a feature of emphysema. Experimental emphysema may be induced by human neutrophil elastase and other elastolytic enzymes but not by nonelastolytic proteases. Disruption of elastic fibers also appears to be the underlying feature of lathyrogen-induced airspace enlargement and of the emphysema in the blotchy mouse. However, there is no evidence of elastic fiber destruction in cadmium-induced airspace enlargement with fibrosis or in emphysema associated with hyperoxia or severe starvation. Thus, elastic fiber disruption is not common to all forms of experimental emphysema. We posit that airspace enlargement may be a stereotyped response of the lungs to different injuries. Emphysema can be induced in experimental animals by repeated induction of pulmonary neutrophilia. However, the evidence for involvement of neutrophil elastase in human emphysema is not clear: there are studies using a variety of approaches that weigh on both sides of the question. There is also in vitro evidence that alveolar macrophages can degrade elastin or elastic fibers with which they are in contact by means of a metalloelastase or the cooperative action of plasminogen activator and an acid cysteine protease. We conclude that the pathogenesis of emphysema is complex. Neutrophil elastase likely plays a major role in the development of some forms of emphysema, but our understanding of the interactions between the alveolar walls and neutrophils is still fragmentary.
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PMID:Putative role of neutrophil elastase in the pathogenesis of emphysema. 206 48

During their development, mononuclear phagocytes express a changing profile of proteinases that may participate in the degradation of elastin and other extracellular matrix components. Neutrophil elastase is produced and stored in azurophil-like granules in immature mononuclear phagocytes. Monocytes contain small amounts of neutrophil elastase but do not synthesize the enzyme. Macrophages neither synthesize nor contain neutrophil elastase, but they can internalize and secrete scavenged neutrophil elastase. Human alveolar macrophages synthesize cysteine proteinases including cathepsin L, a lysosomal enzyme with elastolytic activity at an acidic pH. Macrophages from several animal species synthesize an approximately 22-kD metalloelastase that, in the mouse, is secreted as a zymogen of about 36 kD. In addition to its direct elastolytic properties, this metalloelastase may also promote elastolysis by cleaving alpha 1-antiproteinase and thus protecting neutrophil elastase from inhibition. A human counterpart of this enzyme has not yet been purified; however, the elastolytic activity of human macrophages appears to depend predominantly on the activity of one or more metalloproteinases. Because elastin is intertwined with other matrix components in natural matrices, degradation of elastin in vivo probably involves cooperation of multiple proteinases to uncover macromolecules that mask the elastic fibers. Degradation of matrix may be localized to pericellular sites, where proteinases are protected from inhibitors and where potentially surface-bound enzymes may be concentrated. Complete breakdown of matrix may be completed within the cells after partially cleaved molecules are internalized. Growth and remodeling of the extracellular matrix must involve highly coordinated interactions between cells, cytokines, proteinases, proteinase activators and inhibitors, as well as the matrix itself. The intrapulmonary process resulting in emphysema probably involves equally complex interactions. Mononuclear phagocytes accumulate in large numbers in the lung in response to cigarette smoking, and they may play a role in the pathogenesis of the alveolar septal injury that characterizes pulmonary emphysema.
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PMID:Elastin degradation by mononuclear phagocytes. 206 50

Pseudomonas aeruginosa, which may cause severe lung infections, secretes a metalloelastase that may interfere with the assay of neutrophil elastase and cathepsin G in lung secretions. Using nuclear magnetic resonance spectroscopy, we have shown that P. aeruginosa elastase (PsE) cleaves succinyl-Ala3-p-nitroanilide between the first and the second alanine residue, rendering this substrate inefficient for the assay of neutrophil elastase. The cleavage occurs with a kcat/Km of 2.4 X 10(3) M-1 s-1, a value eightfold higher than the kcat/Km for the chromogenic cleavage of succinyl-Ala3-p-nitroanilide by neutrophil elastase. P. aeruginosa elastase also cleaves the elastase substrate succinyl-Ala3-Val-p-nitroanilide between the second and the third alanine residue and the cathepsin G substrate succinyl-Ala2-Pro-Phe-p-nitroanilide at the Pro-Phe linkage. By contrast, methoxysuccinyl-Ala2-Pro-Val-p-nitroanilide, another elastase substrate, is not hydrolyzed by the bacterial enzyme. Our data indicate that synthetic substrates should be used with caution to assay elastase and cathepsin G in lung secretions or other biologic fluids in which metalloproteinases may be present.
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PMID:Nonchromogenic hydrolysis of elastase and cathepsin G p-nitroanilide substrates by Pseudomonas aeruginosa elastase. 251 50

Experiments performed in vitro have demonstrated that leukocyte neutral proteases produce an important mediator of inflammation, C5a, by proteolysis of the C5 component of the complement system. Cystic fibrosis (CF) lung fluids were characterized by high levels of neutrophils (39% of total cells versus 2% in normals) and contained significantly elevated amounts of elastolytic activity (mean 17.7 ng/micrograms total protein) compared to the lung fluids obtained from normal volunteers (0.2 ng elastolytic activity/micrograms protein, p = 0.001). The objective of these studies was to determine if complement activation and complement-derived chemotactic activity are present in CF lung fluids. C3c peptide representing activation of C3 could not be identified in the bronchial-alveolar lung lavage fluids of normal subjects but was readily identified by means of crossed immunoelectrophoresis in CF lung fluids (n = 9, mean 49% of C3); the mean level of C3 was decreased in CF lung specimens. Chemotactic activity was significantly elevated in lung fluids of the CF patients when compared to normal lung fluids. Using gel-filtration chromatography and a sensitive radioimmunoassay the chemotaxin present in CF specimens was identified as the anaphylatoxin C5a. C5a levels in the bronchial-alveolar lavage fluids of CF patients was inversely related to volume in liters expired in 1 s of a forced expiratory maneuver expressed as a percent of vital capacity determined from a forced expiratory maneuver (r = -0.72). Because there was a direct relationship between the total elastolytic activity present in CF airways and the concentration of C5a (r = 0.97, p = 0.03), it was postulated that airway proteases with elastolytic activity also cleave C5, nonimmunologically producing C5a. Detailed inhibition assays revealed that much of the total elastolytic activity had the inhibition profile of a serine proteinase. The levels of the serine proteinases were closely correlated with the numbers of neutrophilic leukocytes present per ml of lavage fluid (r = 0.7, p = 0.05). However, inhibitors of leukocyte serine proteases did not prevent the generation of additional chemotactic activity and the proteolysis of radiolabeled C5 substrate was not prevented by inhibitors of neutrophil elastase. Although the purified metalloelastase of Pseudomonas aeruginosa was active on cell-bound and free C5 yielding C5a, inhibition of this bacterial protease in CF lung fluids only partially blocked cleavage of the alpha- and beta-chains of C5.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Complement activation in cystic fibrosis respiratory fluids: in vivo and in vitro generation of C5a and chemotactic activity. 354 Aug 28

EPI-hNE4 (depelstat) is a potent inhibitor of human neutrophil elastase derived from human inter-alpha-trypsin inhibitor and designed to control the excess proteolytic activity in the sputum of cystic fibrosis patients. We analyzed its resistance to the proteolysis it is likely to encounter at inflammatory sites in vivo. EPI-hNE4 resisted hydrolysis by neutrophil matrix metalloproteases (MMPs) and serine proteases that are released from activated neutrophils in inflammatory lung secretions, including MMP-8 and MMP-9, and the elastase-related protease 3 and cathepsin G. It also resisted degradation by epithelial lung cell MMP-7 but was broken down by the Pseudomonas aeruginosa metalloelastase pseudolysin, when used in a purified system, but not when this protease competed with equimolar amounts of neutrophil elastase. We also investigated the inhibitory properties of EPI-hNE4 at the surface of purified blood neutrophils and in the sputum of cystic fibrosis patients where neutrophil elastase is in both a soluble and a gel phase. The elastase at the neutrophil surface was fully inhibited by EPI-hNE4 and formed soluble complexes. The elastase in cystic fibrosis sputum supernatants was inhibited by stoichiometric amounts of EPI-hNE4, allowing titration of the protease. But the percentage of inhibition in whole sputum homogenates varied from 50 to 100%, depending on the sample tested. EPI-hNE4 was rapidly cleaved by the digestive protease pepsin in vitro. Therefore, EPI-hNE4 seems to be an elastase inhibitor suitable for use in aerosols to treat patients with cystic fibrosis.
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PMID:EPI-hNE4, a proteolysis-resistant inhibitor of human neutrophil elastase and potential anti-inflammatory drug for treating cystic fibrosis. 1662 47