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Biomedical subjects

W Hornebeck

Publications and source records attributed to W Hornebeck.

At least 109 records · Page 6Linked to original sources
PubMed1988

Characterization of human skin fibroblasts elastase activity.

We present evidence that enzyme activity hydrolyzing Succinoyl trialanine paranitroanilide (Suc(Ala)3NA) expressed by Human Skin Fibroblasts (HSF) in culture could be attributed to the concerted action of an endopeptidase and an aminopeptidase(s). Both endopeptidase and aminopeptidase activities were strongly inhibited by metal chelating agents and Copper and Zinc ions but were insensitive to Tissue Inhibitor of Metallo Proteases (TIMP). These protease activities coeluted on ion exchange chromatography (DEAE Tris acryl M) and were further separated by high-performance liquid chromatography HPLC (TSK 3000 SW). The endopeptidase activity, designated as HSF E1, was eluted at the position corresponding to an Mr equal to 94,000. It has only a limited elastinolytic potential as evaluated on 3H insoluble elastin, but it extensively degrades human skin elastic fibers as directly assessed on human skin tissue sections and further quantitated by automated image analysis. The level of HSF E1 increases with the number of fibroblast passages.

Adult↗
PubMed1988

Elastase activity of bronchoalveolar cells in advanced pulmonary sarcoidosis.

Elastase activities were investigated in bronchoalveolar lavage (BAL) cells from healthy controls (C, n = 8) and patients with untreated mediastinopulmonary sarcoidosis at different stages: I (n = 5), II (n = 7), IIIA (n = 3), IIIB (n = 4). Elastase activities (EA and ELA) were measured against a synthetic substrate, succinyl-trialanine-paranitroanilide (SLAPN) and radiolabelled ligamentum nuchae 3H insoluble elastin (specific radioactivity 3.7 MBq.mg-1). A significant increase of ELA of BAL cells was observed in patients (S III), in particular those exhibiting fibrotic roentgenographic patterns and a higher number of polymorphonuclear cells. On the contrary, EA of BAL cells showed no variation between different stages of sarcoidosis. ELA was never detected in the macrophage culture medium and appeared to be mainly associated with non-adherent macrophages, whereas EA appeared to be preferentially associated with adherent macrophages. The inhibitory profiles of ELA and EA were investigated using general proteinase inhibitors and also compounds interacting specifically with leucocyte elastase. ELA was mainly due to a serine protease, which has a sensitivity to inhibitors similar to leucocyte elastase and is increased in advanced stages of sarcoidosis. EA appears to be only slightly modified, if at all, in sarcoidosis and is probably related to the action of both a serine protease and a metalloenzyme. Thus, only ELA yields diagnostic information concerning stage III of sarcoidosis associated with a fibrotic or bullous roentgenographic pattern.

Adult↗
PubMed1988

Morphometric analysis of the degradation of human skin elastic fibres by human leukocyte elastase (EC 3-4-21-37) and human skin fibroblast elastase (EC 3-4-24).

The degradation of human skin preelastic fibres (PEF) namely oxytalan and elaunin fibres, and that of mature skin elastic fibres (EF) by human leukocyte elastase and purified human fibroblast elastase was studied by morphometric analysis. Leukocyte elastase hydrolyzed both types of fibres; Elaunin and mature elastic fibres were found particularly sensitive to degradation by this proteinase. Skin PEF and EF from 59-67 yr-old individuals were degraded to a greater extent by this proteinase than those from the two younger individuals analyzed (18 and 24 yrs old). Human skin fibroblast elastase mainly hydrolyzed PEF. It possessed only a limited action toward mature dermal elastic fibres. At the highest dose of proteinase used, the volume fraction of EF was reduced by 50% in youngest skins and by 25% in the oldest ones.

Elastin↗
PubMed1988

Effect of sodium oleate on the hydrolysis of human plasma fibronectin by proteinases.

Oleic acid binds in a saturable fashion to human plasma fibronectin (FN). Analysis of the binding indicated the presence of a high affinity binding site with nKa approximately equal to 10 uM-1. Furthermore, it was found that binding of sodium oleate to FN modulated its susceptibility to degradation by various proteinases. FN saturated with sodium oleate was hydrolysed at a higher rate by trypsin, cathepsin D, thermolysin and pancreatic elastase than native FN. In contrast, sodium oleate inhibits the activity of two human granulocyte proteinases, human leucocyte elastase (HLE) and cathepsin G on either FN or on their respective specific synthetic substrates (at concentrations ranging from 10(-6) mM to 10 mM). Cathepsin G inhibition was non-competitive and gave a Ki in the 10 uM range similar to the previously reported inhibitory constant of oleic acid toward HLE.

Binding Sites↗
PubMed1987

Inhibition by elastase inhibitors of the formyl Met Leu Phe-induced chemotaxis of rat polymorphonuclear leukocytes.

Rat leukocyte elastase has been purified successively by AH-Sepharose Kappa-elastin affinity chromatography and by ion exchange chromatography on a carboxymethyl Sephadex resin. It has great similarities with human leukocyte elastase in its molecular weight, substrate specificity and inhibitory profile. The effect of rat leukocyte elastase inhibitors in influencing the chemotactic response of rat PMN to fMetLeuPhe has been compared to that of other proteinase inhibitors. The results indicated that oleoyl (Ala)2ProValCH2Cl, a specific inhibitor of human and rat leukocyte elastases and Eglin C, which also inhibits human and rat cathepsin G, are among the powerful inhibitors of rat PMN chemotaxis induced by the formyl oligopeptide. This suggests that these neutral proteinases, in addition to their known participation in connective tissue catabolism, could play a role in PMN locomotion and chemotaxis.

Animals↗
PubMed1986

Inducible adhesion of mesenchymal cells to elastic fibers: elastonectin.

The addition of highly purified elastic fibers to confluent human skin fibroblast or porcine aorta smooth muscle cell cultures resulted in a time-dependent, strong adhesion of the fibrils to the cell surface. The kinetics of adhesion was studied by video/time-lapse cinematography. After a 0.5-1 hr lag period, adhesion progressed to a maximum amount in 3-6 hr in the described conditions. Adhesion is strongly accelerated by the prior addition of soluble elastin peptides (kappa-elastin) to the cultures. Cycloheximide inhibits this induced adhesion. Adherent elastic fibers can be detached by treatment with elastase and trypsin but not with collagenase. The radioactive proteins adhering to elastic fibers, after a 6-hr incubation of the induced cultures in presence of [35S]methionine, were extracted and analyzed by NaDodSO4/PAGE. The proteins strongly adhering to the elastic fibers had apparent molecular sizes of about 120, 67, 60, and 45 kDa. Only the 120-kDa protein band showed a significant increase of its associated radioactivity in the induced cultures as compared to the noninduced cultures. We propose that the 120-kDa protein is responsible for the induced adhesion of mesenchymal cells to elastic fibers and designate it "elastonectin."

Animals↗
PubMed1985

Fatty acid peptide derivatives as model compounds to protect elastin against degradation by elastases.

Peptide sequences which fit the extended binding sites of porcine pancreatic elastase and human leukocyte elastase were covalently coupled to oleic acid. These compounds behave as competitive inhibitors towards both elastases. The coupling of fatty acid moiety to the peptide greatly decreases its inhibitor constant (Ki) vs human leukocyte elastase (Ki for Oleoyl(Ala)2ProValine: 3.0 (10(-6)M). It is less active on porcine pancreatic elastase (Ki for Oleoyl(Ala)2ProAlanine: 3.8 10(-4)M). The modifications of the carboxylic end group of the peptide to an aldehyde further greatly enhanced the inhibition capacity of the compound towards leukocyte elastase (Ki for Oleoyl(Ala)2ProAlaninal: 0.7 microM). Oleoyl peptide derivatives were seen to bind in a saturable fashion to purified insoluble elastin, and decreased the susceptibility of the macromolecule to hydrolysis by both pancreatic and leukocyte elastases. As stoichiometric quantities of elastase (vs inhibitor) could not desorb 3H-oleoyl(Ala)2Pro-Val bound to insoluble elastin, it is postulated that oleoyl peptide derivatives may act as bifunctional agents. This contention was further strengthened by the comparison of the adsorption curves of elastase to untreated insoluble elastin and elastin saturated with oleoyl peptide derivatives respectively. It was shown finally that Oleoyl(Ala)2Pro-Valine was also capable of inhibiting elastases in their adsorbed form to insoluble elastin.

Adsorption↗
PubMed1985

On the influence of the substrate (elastin) in elastase-alpha 1 antitrypsin interactions.

Evidence is presented showing that elastin(s) influences the interactions between porcine pancreatic elastase and its main plasma inhibitor alpha 1-proteinase inhibitor (e.g. alpha 1 antitrypsin). The rate constant of association (kon) between the proteinase and alpha 1 antitrypsin is decreased from 2.8 10(5) M-1 sec-1 to 1.24 10(5) M-1 sec-1 in presence of 1 mg/ml of insoluble elastin and 0.83 10(5) M sec-1 in presence of the same concentration of alpha-elastin. With both elastins this kon decrease was found concentration dependent indicating that these compounds compete in a similar fashion with alpha 1 AT for the binding of elastase. Such an effect was not observed when elastin(s) was replaced by bovine serum albumin. Experiments were designed as previously published (B. Robert et al. 1974) in order to evaluate the capacity of alpha 1 AT to inhibit preadsorbed elastase on to insoluble elastin and also diffusible protease molecules. It was found that even at concentrations far exceeding the equivalence with elastase, alpha 1 AT was only partially able to inhibit both preadsorbed enzyme (approximately 50 per cent) and diffusible protease (approximately 90 per cent).

Animals↗
PubMed1984

Evidence by in vivo and in vitro studies that binding of pycnogenols to elastin affects its rate of degradation by elastases.

Procyanidol oligomers and (+) catechin bound to insoluble elastin markedly affect its rate of degradation by elastases. Insoluble elastin pretreated with procyanidol oligomers (PCO) was resistant to the hydrolysis induced by both porcine pancreatic and human leukocyte elastases. The quantitative adsorption of pancreatic elastase was similar on either untreated or PCO-treated elastin suggesting that the binding of this compound to elastin increases the non-productive catalytic sites of elastase molecules. (+) Catechin-insoluble elastin complexes were partially resistant to the degradation induced by human leukocyte elastase but were hydrolysed at the same rate as untreated samples by a constant amount of pancreatic elastase. In addition, the coacervation profile of kappa-elastin peptides as a function of temperature is greatly modified in presence of these flavonoids. We conclusively evidenced that PCOs bind to skin elastic fibres when injected intradermally into young rabbits. As a result, these elastic fibres were found more resistant to the hydrolytic action of porcine pancreatic elastase when injected to the same site. These in vivo studies further emphasized the potential effect of these compounds in preventing elastin degradation by elastase(s) as occurred in inflammatory processes.

Animals↗
PubMed1984

Ultrastructural and biochemical modifications of rabbit arteries induced by immunization with soluble elastin peptides.

Immunization of rabbits with soluble elastin peptides (kappa 1-elastin) in complete Freund's adjuvant resulted in morphological and biochemical modifications in aorta and in lung arterioles. The elastic fibers of both tissues appeared fragmented at the light microscopical and ultrastructural levels. The presence of IgG at the site of lysed elastic fibers could be evidenced by immunological techniques. In agreement with these findings, a significantly increased elastase-type protease activity could be demonstrated in aorta extracts from the immunized animals as compared to those obtained from control animals. The biosynthetic activities of aorta explants of rabbits immunized with kappa 1-elastin maintained in organ culture conditions were considerably reduced, as shown by the decrease of incorporation of [14C]lysine and [14C]glucosamine in aorta macromolecules. These results show that anti-elastin antibodies may well be involved in the pathological modifications of the arterial wall and especially in the triggering of the degradation of elastic lamellae.

Animals↗
PubMed1984

Interaction between elastin and elastases and its role in the aging of the arterial wall, skin and other connective tissues. A review.

Elastic fibers are progressively lysed during maturation and aging and in an accelerated fashion in several aging diseases such as diabetes, arteriosclerosis, emphysema and several skin diseases. Several enzymes (elastase-type proteases) were isolated in recent years in our laboratory which appear to be involved in these processes. A cell membrane bound serine protease was isolated from arterial smooth muscle cells and was shown to increase with in vitro aging of the cells. A metallo-protease was isolated from skin fibroblasts and was shown to be capable of attacking the constituents of elastic fibers, mainly the microfibrillar glycoproteins and also the desmosine cross linked elastin in vivo. This partially purified fibroblast enzyme was shown to attack these elastic fibers when injected into the dermis. A new selective staining procedure was used to visualise and quantitate, by computerized image analysis, the skin elastic fibers in normal and pathological human or animal skin biopsies. This method, combined with the injection of elastase in rabbit skins, alone or together with inhibitors, enables the ex vivo/in vivo study of elastase action (and of its inhibition).

Adult↗
PubMed1984

On the presence of a metalloprotease in human skin fibroblasts that degrades the human skin elastic fiber system.

Succinyl-trialanine paranitroanilide, a specific synthetic substrate of elastases, was shown to be hydrolyzed by Triton X-100 extracts of human skin fibroblasts at near neutral pH. The neutral endopeptidase has been partially purified by ion exchange chromatography (DEAE Sephadex) and affinity chromatography using an AH-Sepharose (Ala)3 column. The enzyme has been purified 85-fold and appears to be a metalloprotease as shown by its inhibitory profile. In its partially purified form, the neutral endopeptidase was found inactive toward benzoyl arginine paranitroanilide, benzoyl tyrosine paranitroanilide, azocasein, type I collagen, and [3H]ligamentum nuchae-insoluble elastin. Structural glycoprotein microfibrils isolated from porcine aorta are extensively degraded by this neutral protease. It could also hydrolyze, but to a lesser extent, insoluble elastin purified from human aortas; it was, however, found inactive toward bovine ligamentum nuchae elastin. Its potentiality to degrade the human skin elastic fiber system (namely elastic fibers, oxytalan, and elaunin fibers) has been assessed by a morphometric analysis of the length of these fibers (on tissue sections appropriately stained to identify the components of the elastic fiber system) prior to and after enzyme action. Analysis of the data obtained by morphometry indicated that this neutral protease attacked rapidly both elaunin and oxytalan fibers of human dermis, but only slowly the mature elastic fibers.

Cells, Cultured↗
PubMed1984

Differentiation of the elastase-type protease of platelets from other elastases.

Elastase activities were determined near neutral pH on several specific substrates using platelet-derived preparations mixed with decreasing amounts of leukocytes. Activities were extrapolated to zero leukocyte content enabling the estimation of intrinsic platelet elastase activity. In contrast to human leukocyte elastase, metal chelating agents inhibited partly the elastase activity of the platelet extract and soybean trypsin inhibitor did not modify its activity. Serine active site titrants (phenylmethane sulfonyl fluoride) as well as acetyl-di-L-alanyl-L-propyl-L-valine chloromethylketone completely abolished the activity of platelet lysates. The platelet protease was purified from Triton X-100 platelet lysates. No cross-reactivity could be demonstrated by immunoelectrophoresis with either porcine pancreatic elastase or human leukocyte elastase using monospecific antisera. Applying gel electrophoresis, most of the elastase activity of the platelet protease migrated towards the anode, whereas the pancreatic and leukocyte elastases migrated towards the cathode. The anionic character of the platelet enzyme might explain its capacity to degrade better elastin treated with cationic detergents in contradistinction to other elastases which act better on anionic detergent-treated elastins.

Animals↗
PubMed1983

Properties and subcellular localization of elastase-like activities of arterial smooth muscle cells in culture.

The properties and subcellular localization of the elastase-like activities of smooth muscle cells cultured from pig aortas have been investigated. Homogenates of the cells hydrolysed N-succinyl-L-alanyl-L-alanyl-L-alanine-p-nitroanilide, a synthetic substrate for elastases, with a distinct pH optimum of 8.2 and hydrolysed insoluble elastin with a distinct pH optimum of 8.5. Both enzyme activities were directly proportional to the concentration of homogenate in the assay mixture. The activities toward both substrates were inhibited by phenylmethylsulphonyl fluoride and were therefore probably due to a serine peptidase(s). The activities were also inhibited by EDTA and, in a dose-related manner, by alpha 1-antiprotease. Pepstatin, which inhibits cathepsin D, and leupeptin, which inhibits cathepsin B, did not significantly inhibit the elastase-like activities in these cells. The cells were homogenized and a post-nuclear supernatant subjected to sucrose density gradient centrifugation. The distribution of elastase-like activity toward both substrates was similar to that of the plasma membrane marker 5'-nucleotidase, and distinct from those of marker enzymes for the other organelles. Cells were also homogenized with digitonin, which selectively increases the equilibrium density of the plasma membrane. The equilibrium densities of both 5'-nucleotidase and of the elastase-like activities were increased considerably, confirming the plasma membrane localization of the elastase-like activities. The subcellular localization of the elastase-like activities of arterial smooth muscle cells is therefore consistent with a role for them in the degradation of elastin in the normal arterial wall and in atherosclerotic lesions.

Animals↗
PubMed1983

Dinitrophenyl-pepstatins as active-site-directed localization reagents for cathepsin D.

1. N-Pepstatinyl-N'-dinitrophenyl-1,6-diaminohexane, a potential active-site-directed localization reagent for cathepsin D, was found to bind non-specifically to immuno-precipitates containing cathepsin D. 2. Three new water-soluble localization reagents were synthesized, by using NN'-bis-(3-aminopropyl)piperazine, 3-oxa-1,5-diamino-pentane or 3,6-dioxa-1,8-diamino-octane, as spacer arms between the pepstatin and dinitrophenyl moieties. 3. The hydrophilic dinitrophenyl-pepstatins were all tight-binding inhibitors of cathepsin D at pH 3.5, but showed little or no binding to immuno-precipitates containing the inactive enzyme at pH 7.4. 4. Gel-chromatographic experiments showed that, at pH 5.0, all the dinitrophenyl-pepstatins were bifunctional reagents able to bind cathepsin D and anti-dinitrophenyl antibody at the same time. Enzyme-inhibitor-antibody complexes were not formed at pH 7.4, thus confirming that the reagents were active-site-directed. 5. Cultured human synovial cells were fixed and incubated with the dinitrophenyl-pepstatins at pH 5.0 or pH 7.4. After washing briefly, the cells were incubated at the appropriate pH value with anti-dinitrophenyl antibody labelled with fluorescein. When examined by fluorescence microscopy the cells stained at pH 5.0 showed fluorescent perinuclear granules, which were not seen in the cells treated at pH 7.4. The distribution of cathepsin D, determined by indirect immuno-fluorescence at pH 7.4, closely resembled that revealed by the dinitrophenyl-pepstatins at pH 5.0. 7. NN'-(3-Pepstatinylaminopropyl-3'-dinitrophenylaminopropyl)piperazine gave the most intense lysosomal staining and showed no non-specific binding. We conclude that this reagent is suitable for the subcellular localization of the active conformation of cathepsin D.

Binding Sites↗