[Corneal burns and matrix metalloproteinases (MMP-2 and -9): the effects of human amniotic membrane transplantation]. / Brûlures cornéennes et métalloprotéases: influence des greffes de membranes amniotiques.

PURPOSE: Human amniotic membranes have recently been used in ophthalmology to restore deleted ocular surface after burns. Matrix metalloproteinases-2 and -9 have been implicated in the development of neovascularization. In this study, MMP-2 and MMP-9 expression was analyzed by in situ zymography on rabbit corneal chemical burns with and without human amniotic membrane graft. METHOD: Corneal neovascularization was induced in 10 Fauve de Bourgogne rabbits by means of a heptanol chemical burn on controlled deep keratotomy using a Chiron ALK-E corneal shaper. Half of rabbits received acute amniotic membrane transplantation 30mn after chemical burn; the remaining five rabbits received medical treatment. In situ zymography is a recent nondestructive technique which preserved the fine morphological details of the cornea and showed the active enzyme location in different corneal layers. The MMP-2 and -9 substrate was gelatin, which was detected by fluorescent microscopy. RESULTS: There was an overexpression of MMP-2 and -9 in corneal burns versus control corneas. Expression of MMP-2 and -9 was low in corneal burn without amniotic membrane graft. Following amniotic membrane transplantation, MMP-2 and -9 were strongly expressed and clinical neovascularization and inflammation decreased. Active enzymes were located in epithelium layers in the uncovered group. In the covered group, the active enzymes were located in the anterior and posterior stromal layers. CONCLUSION: The results support a role for MMP-2 and MMP-9 in corneal burn neovascularization. Amniotic membrane transplantation can play a protective role by up-regulation of their biological expression.

Effect of procyanidolic oligomers on the permeability of the blood-brain barrier.

Blood-brain barrier (BBB) is the site of regulatory mechanisms which control the exchange of substances between the brain and the blood through the wall of 'true' brain capillaries with tight junctions between endothelial cells. In some pathological situations the permeability of the BBB is increased because of a partial proteolytic degradation of some constituents of the capillary basement lamina. In such cases it is important to restore normal permeability. The effect of procyanidolic oligomers (PCO) on the BBB was investigated in vivo with quantitative morphologic procedures. We also investigated the action of this drug on collagen and basement lamina constituents (Matrigel) in vitro. Collagenase injected in lateral brain ventricles was shown to increase BBB permeability. Per os administration of PCO to rats greatly increased the resistance of brain capillaries to bacterial collagenase, as shown by the inhibition of the diffusion of fluorescein-isothiocyanate-marked dextran particles from the blood-stream into the brain tissues. Calf skin collagen pretreated in vitro with PCO became more resistant to the hydrolytic action of collagenase. Similar, even more intense protective effect was seen when basal lamina constituents containing type IV collagen was incubated with PCO before exposure to pronase. These in vitro effects may partly explain the in vivo protective effect of PCO against the alteration of brain capillaries by i.v. injected bacterial collagenase.

Human CD38 is an authentic NAD(P)+ glycohydrolase.

The leucoyte surface antigen CD38 has been shown to be an ecto-enzyme with multiple catalytic activities. It is principally a NAD+ glycohydrolase that transforms NAD+ into ADP-ribose and nicotinamide. CD38 is also able to produce small amounts of cyclic ADP-ribose (ADP-ribosyl cyclase activity) and to hydrolyse this cyclic metabolite into ADP-ribose (cyclic ADP-ribose hydrolase activity). To classify CD38 among the enzymes that transfer the ADP-ribosyl moiety of NAD+ to a variety of acceptors, we have investigated its substrate specificity and some characteristics of its kinetic and molecular mechanisms. We find that CD38-catalysed cleavage of the nicotinamide-ribose bond results in the formation of an E.ADP-ribosyl intermediary complex, which is common to all reaction pathways; this intermediate reacts (1) with acceptors such as water (hydrolysis), methanol (methanolysis) or pyridine (transglycosidation), and (2) intramolecularly, yielding cyclic ADP-ribose with a low efficiency. This reaction scheme is also followed when using nicotinamide guanine dinucleotide as an alternative substrate; in this case, however, the cyclization process is highly favoured. The results obtained here are not compatible with the prevailing model for the mode of action of CD38, according to which this enzyme produces first cyclic ADP-ribose which is then immediately hydrolysed into ADP-ribose (i.e. sequential ADP-ribosyl cyclase and cyclic ADP-ribose hydrolase activities). We show instead that the cyclic metabolite was a reaction product of CD38 rather than an obligatory reaction intermediate during the glycohydrolase activity. Altogether our results lead to the conclusion that CD38 is an authentic 'classical' NAD(P)+ glycohydrolase (EC 3.2.2.6).

Coordinated regulation in human T cells of nucleotide-hydrolyzing ecto-enzymatic activities, including CD38 and PC-1. Possible role in the recycling of nicotinamide adenine dinucleotide metabolites.

The human leukocyte surface Ag CD38 was recently identified as a nicotinamide adenine dinucleotide (NAD)(+)-glycohydrolase ecto-enzyme, degrading NAD into nicotinamide and ADP-ribose. We show here that expression of CD38 is increased in the Jurkat T cell line after treatment with agents that augment intracellular cAMP, with the permeant cAMP analogue dibutyryl-cAMP (db-cAMP), and also with PMA, which activates protein kinase C. Treatment of human PBL T cells with db-cAMP or submitogenic doses of PMA also increased CD38 expression. Two other nucleotide-hydrolyzing activities were induced on the T cell surface concomitantly with CD38: the human PC-1 molecule, a nucleotide phosphodiesterase/pyrophosphatase that produces AMP from NAD or ADP-ribose, and a nucleotidase that produces adenosine from AMP, but which may be distinct from the CD73 5'-nucleotidase. All three enzymes were up-regulated after stimulation of human peripheral blood T cells with PHA. The coordinated regulation of these ecto-enzymes suggested that, besides a possible signaling function, they may recycle extracellular NAD by degrading it to adenosine and nicotinamide, which can be taken up by cells. In support of this hypothesis, db-cAMP-treated Jurkat cells could degrade extracellular NAD for de novo synthesis of purines, while untreated cells could not. Activated lymphocytes are often located in tissues in which cell death is common. It is suggested that the coordinated expression of these enzymes may allow activated T cells to re-use NAD and nucleotides from dead cells.

Elastin derived peptides protect elastic fibres degradation by human neutrophil elastase: in vitro and in vivo studies using a mechanically induced rat gingival inflammatory model.

An elastin peptide (kE57) obtained from organoalkaline hydrolysis of calf ligamentum nuchae insoluble elastin, was isolated by gel permeation on Sephadex G150 and high performance liquid chromatography on a TSK G 3000 SW column. It possessed an average Mr = 57,000 and similar amino acids composition as its insoluble counterpart. kE57 behave as a competitive inhibitor of human neutrophil elastase (HNE) with Ki = 1.4 microM; it also inhibited porcine pancreatic elastase (PPE) but less efficiently Ki = 180 microM. Identification of elastic fibres in rat gingiva was ascertained by light and electron microscopic studies. Morphometric studies indicated that rat gingiva contained similar levels of elastic fibres (= 2%) as human skin; elastic fibres networks from both tissues also displayed high structural analogy. Gingival chronic inflammation was induced in rats by mechanical impaction associated with an hyperglucidic diet. After 5 weeks, the levels of rat gingiva elastic fibres, decreased from Vv = 1.94 +/- 0.1% to Vv = 1.02 +/- 0.06%. Local injections of kE57: 100 micrograms per day, 5 days a week for 5 weeks did restore the integrity of the gingiva elastic fibres network: Vv = 1.84 +/- 0.1. Without influencing leucocyte infiltration, it is proposed that elastin-derived peptides, acting as potent competitive inhibitor of neutrophil elastase involved in periodontitis, might be of therapeutic value.

[Inhibition of elastase activity in human gingival extracts by elastin peptides]. / Inhibition de l'activité élastasique d'extraits de gencives humaines par les peptides d'élastine.

Effects of elastin peptides on elastase activity of gingival biopsy specimen extracts were studied in vitro and in vivo. All the extracts from biopsy specimens from 15 patients with a variety of periodontal diseases demonstrated fairly marked elastase activity. In vitro, addition of elastin peptides produced a mean inhibition of 54% +/- 14% with a concentration of 0.25 mg/ml and a mean inhibition of 90% +/- 6% with 2.5 mg/ml. In vivo treatment of gums with a paste containing 1% elastin peptides reduced elastase activity by 47% in 7 of 8 patients. These data suggest that elastin peptides are effective inhibitors of periodontal elastase activity and may be useful in preparations used for the preventive or curative treatment of periodontal diseases with tissue lysis.

Mechanisms of interaction between human skin fibroblasts and elastin: differences between elastin fibres and derived peptides.

3H-Labelled kappa-elastin peptides (kE:75 kDa molecular weight) were shown to bind to confluent human skin fibroblast (HSF) cultures in a time-dependent and saturable manner. Scatchard analysis indicated the presence of high affinity binding sites with kD = 2.7 x 10(-10) M and 19,000 sites per cell. Binding of kE to its receptor on HSF accelerates and intensifies the adhesion of insoluble elastin fibres (iE) to confluent HSF. Optimal effect was attained for a kE concentration of 0.3 x 10(-9) M close to kD. This stimulatory effect of kE on the binding of iE to HSF could be inhibited by neomycin, retinal and pertussis toxin, substances which act at different levels of the transduction mechanism following the activation of the receptor and the subsequent triggering of cell biological events (chemotaxis, modification of calcium fluxes). The stimulation of iE adhesion to HSF induced by kE as well as kE binding to the cells could be inhibited by lactose and laminin but not by Arg-Gly-Asp-Ser(RGDS) peptides. This indicates that the elastin peptide receptor on HSF possesses lectin-like properties and shares homology with the laminin receptor as also shown for other cell types. None of the substances tested, that is inhibitors of the transduction mechanism, lactose, laminin and Arg-Gly-Asp-Ser(RGDS) peptides were shown to interfere significantly with the binding of iE (in the absence of added kE) to confluent HSF. The proteins adhering strongly to elastin fibres were isolated by a sequential extraction procedure and the final hydrochloride guanidinium-DTT extract was analysed by SDS-PAGE under reducing conditions, Western blots using specific antibodies against several connective tissue proteins and affinity for [3H]-kE following nitrocellulose electro-transfer of proteins. Fibronectin, vitronectin, tropoelastin(s), and a 120 kDa cysteine rich glycoprotein previously designated as elastonectin were identified. Among these proteins, [3H]-kE was found to bind exclusively to a 65 kDa protein that could be eluted selectively from elastin fibres with a neutral buffer containing 100 mM lactose. Therefore the elastin peptide receptor on human skin fibroblasts shares properties with the elastin receptor characterized from other cell types. Conformational differences between elastin peptides and elastin fibres could explain the differences in the mechanisms of interactions between elastin fibres and elastin peptides with HSF in culture. The stimulatory effect of elastin-derived peptides on the adhesion of elastin fibres to HSF could have implications in the oriented biosynthesis of elastin fibres.

Interaction between elastin and tumor cell lines with different metastatic potential; in vitro and in vivo studies.

Interactions between the extracellular matrix macromolecules and tumor cells are critical in the process of metastasis formation. We show here that elastins (both mature insoluble elastin and a 75-kDa soluble peptide: K-elastin) adhere rapidly to two cell lines with high metastatic capacities: a metastatic lung carcinoma cell line (3LL-HM) and a human amelanotic melanoma cell line (A-2058); by contrast the low-metastatic Lewis lung carcinoma cell line variant as well as a rhabdomyosarcoma cell line with a low metastatic potential bind to elastins to a much lower extent. 3H-labelled K-elastin was used in order to study elastin--3LL-HM interaction. It was found to be saturable (2 ng 3H-labelled K-elastin/10(6) cells), with one class of high-affinity binding sites having Kd equal to 1.3 nM and 16,000 sites/cell. The binding of K-elastin to 3LL-HM cells at its receptor triggered several cell responses; (a) increase of intracellular Ca2+ concentration; (b) induction of 3LL-HM chemotaxis toward the K-elastin gradient; (c) stimulation of the adherence of mature insoluble elastin. In contrast to non-transformed cells such as fibroblasts and smooth muscle cells, the adhesion kinetics of insoluble elastin to 3LL-HM did not exhibit a lag period; the rapid binding of insoluble elastin to the tumor cells was followed by its slow detachment from the cells, which lasted for 6 h. 3LL-HM cells but not human skin fibroblasts were shown to secrete elastinolytic activity inhibitable by metal-chelating agents. In vivo studies were performed in order to evaluate the influence of K-elastin binding to 3LL-HM cells on their ability to form lung colonies in mice. It was shown that pretreatment of 10(4) 3LL-HM cells with 10 microM K-elastin and the simultaneous i.v. injection into mice of 750 micrograms K-elastin together with the highly metastatic cells was able to reduce the number of lung colonies by more than 70% after 12 days.

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.

Inhibition of leucocyte elastase by heparin and its derivatives.

Leucocyte proteinases, e.g. leucocyte elastase and cathepsin G, are inhibited by heparin. The activities of pig pancreatic and Pseudomonas aeruginosa elastases are unaffected by this polysaccharide. Heparin derivatives of known Mr and degree of sulphation were isolated. The inhibition of leucocyte elastase by these oligosaccharides can be classified as tight-binding hyperbolic non-competitive. Ki values ranged from 40 nM to 100 microM and were found to be inversely correlated with the chain length of the oligosaccharides. Desulphated compounds lacked inhibitory potential towards leucocyte elastase. Over-O-sulphated di- and tetra-saccharides are more potent inhibitors than their over-N-sulphated counterparts. It is proposed that the therapeutic use of heparin and its derivatives could be extended to disease states such as emphysema and rheumatoid arthritis, where the role of leucocyte elastase has been clearly established.

Prevention by calcitonin of the pathological modifications of the rabbit arterial wall induced by immunization with elastin peptides: effect on vascular smooth muscle permeability to ions.

Immunization of rabbits with elastin peptides prepared from purified bovine ligamentum nuchae elastin produces calcified arteriosclerotic lesions and fragmentation of elastic lamellae. Simultaneous administration of porcine calcitonin largely prevents the development of lesions. Experiments were carried out to clarify the mechanisms involved in the development of lesions as well as those involved in the preventive effect of calcitonin. Control experiments were carried out using bovine serum albumin (BSA) as antigen. Circulating antibodies and soluble immune complexes increased steadily in the sera of animals immunized with elastin peptides or BSA. The cellular immune reaction was weak as assessed by [3H]thymidine incorporation into lymphocytes in the presence of antigen or phytohemagglutinin. Arterial lesions appeared only in the animals immunized with elastin peptides, not in those immunized with BSA. Ion flux measurements were also carried out on strips of aorta obtained from immunized and control animals. Immunization with elastin peptides significantly increased the ouabain-insensitive 22Na+ efflux, the 86Rb efflux (indicator of K+ efflux), and the 45Ca2+ influx. Simultaneous calcitonin administration prevented the increase in Ca2+ influx but did enhance passive permeability to Na+ and K+ as well as the sodium pump. When calcitonin was administered without immunization, it decreased arterial smooth muscle permeability to Na+ and K+ and also decreased the basal Ca2+ influx. It is concluded that the pathological modifications of the arterial wall triggered by immunization with elastin peptides is at least partly mediated by the effect of antielastin antibodies and immune complexes on the ion permeability of arterial smooth muscle. Prevention of the increased Ca2+ influx by calcitonin is probably a key effect in the prevention of the development of lesions. The fact that calcitonin alone can modify the ion permeability of arterial smooth muscle suggests that this hormone may play a role in the regulation of vascular homeostasis.

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.

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."

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.

The early arterial effects of renovascular hypertension in rats.

Experimental hypertension in rats increases vascular permeability to tracers such as Trypan blue or colloidal iron. The amount of tracer which enters the tissues examined : brain, skin and aortic wall is proportional to the damage of the vascular wall. The highest permeability increase was seen in the aortic wall, then in the skin. Brain vessels seem to be the most resistant to permeability increase induced by experimental hypertension.

Influence of anthocyanoside treatment on the cholesterol-induced atherosclerosis in the rabbit.

We have studied the effect of treatment with anthocyanosides from Vaccinium myrtillis on cholesterol-induced atheroma of rabbits. We have found that the drug did not modify the serum cholesterol levels, but decreased the proliferation of the intima the extracellular matrix production the calcium and lipid deposition in the aorta, and the DNA and lipid contents. The alterations in the biochemical composition of the isolated brain microvessels were also diminished. The following mechanism may explain the protective action of the treatment: the collagen of the vessel walls participates in the control of vascular permeability. This permeability is increased by a cholesterol-rich diet. The protective drug interacts with collagen, increasing its cross-links, thus diminishing the permeability in small, as well as in large blood vessels.