Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0034067 (emphysema)
 11,506 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This review concerns the reasons why only an estimated 10-15% of patients with alpha-1-antitrypsin (A1AT) deficiency develop the destructive lung disease known as emphysema. The arguments presented revolve around the proteinase-antiproteinase balance in the 'microenvironment' of the epithelial space of the lung. Attention is focused on the balance between destructive enzymes such as neutrophil elastase and protective proteins such as A1AT, secretory leucocyte proteinase inhibitor (SLPI), human elastase inhibitor (HEI) and elafin. When neutrophil elastase is already attached to the elastin fibres the smaller molecules SLPI and elafin appear to be better inhibitors of this enzyme than larger inhibitors such as A1AT and HEI. Furthermore, SLPI and elafin may provide the first line of defence against proteinase attack from neutrophil elastase. In trying to explain the variability in the clinical expression of A1AT-deficiency and the development of emphysema, the importance of changes to A1AT, SLPI and elafin molecules induced by smoking and/or oxygen free radicals has been considered. It is possible that emphysema only develops in patients who have SLPI/elafin deficiency as well as A1AT deficiency.
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PMID:The proteinase-antiproteinase theory of emphysema: a speculative analysis of recent advances into the pathogenesis of emphysema. 944 Nov 32

Excessive proteolytic activity of proteinase 3 (Pr3) has been suggested to be a factor contributing to the pathogenesis of emphysema and other inflammatory disorders. We report here on the kinetics of inhibition of Pr3 by one of its major endogenous inhibitors, the 6-kD inhibitory domain of elafin. The results are consistent with a reaction mechanism in which a single elafin molecule binds a single Pr3 molecule to form a fully reversible complex. The association and dissociation rate constants, and the inhibition constant were measured to be 4.0 x 10(6) M(-1) s(-1), 1.7 x 10(-3) s(-1), and 4.2 x 10(-10) M, respectively. Triton X-100 and dimethyl sulfoxide, which are frequently added in assay mixtures for enzymatic analysis of Pr3 activity, significantly reduced the association rate. A fraction of the total neutrophil content of Pr3 has been reported to be bound to the surface of the plasma membrane of activated and nonactivated neutrophils. In this study, we also measured the reaction rate constants of elafin with Pr3 that had been previously allowed to associate with phospholipid bilayer vesicles. Binding to the model membranes slowed down the association rate to 3.3 x 10(5) M(-1) s(-1), but the membrane-bound Pr3 and elafin formed a more stable complex, with a dissociation rate constant of 9.1 x 10(-4) s(-1). Based on the kinetic parameters determined here and the estimated elafin concentrations in vivo, it may be concluded that elafin plays a limited role in the regulation of proteolytic activity of Pr3 in lung secretions.
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PMID:Kinetics of the inhibition of proteinase 3 by elafin. 1115 54

Few therapeutic options are offered to treat inflammation and alveolar wall destruction in emphysema. The effect of recombinant human pre-elafin, an elastase inhibitor, was evaluated in porcine pancreatic elastase (PPE)-induced emphysema in C57BL/6 mice. In a first protocol, mice received a single instillation of pre-elafin (17.5 pmol/mouse) at 1 h post-PPE and were sacrificed up to 72 h post-PPE. A single instillation of pre-elafin significantly reduced PPE-induced neutrophil accumulation in lungs, as assessed by bronchoalveolar lavage (BAL), by 51%, 71% and 67% at 24, 48 and 72 h, respectively. In a second protocol, mice also received a single dose of PPE, but pre-elafin three times a week for 2 weeks. After 2 weeks, pre-elafin significantly reduced the PPE-induced increase in BAL macrophage numbers, airspace dimensions and lung hysteresivity by 74%, 62% and 52%, respectively. Since G-CSF was previously shown to reduce emphysematous changes in mice, the BAL levels of this mediator were measured 6 h post-PPE in animals treated as described in the first protocol. Pre-elafin significantly increased G-CSF levels in PPE-exposed mice compared to sham- and PPE only-exposed animals. This suggests that the beneficial effects of pre-elafin could be mediated, at least in part, by its ability to increase G-CSF levels in the lung.
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PMID:Increased local levels of granulocyte colony-stimulating factor are associated with the beneficial effect of pre-elafin (SKALP/trappin-2/WAP3) in experimental emphysema. 1691 40

Pre-elafin is a tight-binding inhibitor of neutrophil elastase and myeloblastin; two enzymes thought to contribute to tissue damage in lung emphysema. Previous studies have established that pre-elafin is also an effective anti-inflammatory molecule. However, it is not clear whether both functions are linked to the antipeptidase activity of pre-elafin. As a first step toward elucidating the structure/function relationship of this protein, we describe here the construction and characterization of pre-elafin variants with attenuated antipeptidase potential. In these mutants, the P1' methionine residue of the inhibitory loop is replaced by either a lysine (pre-elafinM25K) or a glycine (pre-elafinM25G) residue. Both mutated variants are stable and display biochemical properties undistinguishable from WT (wild-type) pre-elafin. However, compared with WT pre-elafin, their inhibitory constants are increased by one to four orders of magnitude toward neutrophil elastase, myeloblastin and pancreatic elastase, depending on the variants and enzymes tested. As suggested by molecular modelling, this attenuated inhibitory potential correlates with decreased van der Waals interactions between the variants and the enzymes S1' subsite. In elastase-induced experimental emphysema in mice, only WT pre-elafin protected against tissue destruction, as assessed by the relative airspace enlargement measured using lung histopathological sections. Pre-elafin and both mutants prevented transient neutrophil alveolitis. However, even the modestly affected pre-elafinM25K mutant, as assayed in vitro with small synthetic substrates, was a poor inhibitor of the neutrophil elastase and myeloblastin elastolytic activity measured with insoluble elastin. We therefore conclude that full antipeptidase activity of pre-elafin is essential to protect against lung tissue lesions in this experimental model.
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PMID:Characterization of human pre-elafin mutants: full antipeptidase activity is essential to preserve lung tissue integrity in experimental emphysema. 1748 39