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Biomedical subjects

W Hornebeck

Publications and source records attributed to W Hornebeck.

At least 55 records · Page 3Linked to original sources

Interactions of elastin fibers with fibroblasts a time-lapse cinemicrographic study.

Adhesion of cells to the extracellular matrix is mediated by structural glycoproteins such as fibronectin and laminin, and also elastonectin, whose role is to ensure binding of elastin fibers to cells. Interactions between elastin fibers and human skin fibroblasts cultured in a Rose chamber were investigated by using cinemicrography to observe elastin fiber attachment, detachment, and displacement over a five-day period. Elastin fiber displacement over the cell layer resulted in aggregation, which was measured using morphometry. The total number of isolated elastin fibers or aggregates decreased between 1 h and 8 h and remained stable thereafter. During the same time interval, significant decreases occurred in the numbers of isolated fibers and small aggregates (perimeter < 0.268 mm; surface area < 894 microns 2), whereas larger aggregates were formed. After 15 hours of interaction, none of the aggregates had a perimeter greater than 0.536 mm, consistent with an increase in aggregate compacting. These data demonstrate that elastin-cell interactions do not occur at random. These interactions may play a pivotal role in morphogenesis and in maintaining the integrity of elastic tissues such as the arterial wall, lungs, and skin.

Cells, Cultured↗

Influence of successive and combined ultraviolet A and B irradiations on matrix metalloelastases produced by human dermal fibroblasts in culture.

To study the cumulative influence of UV irradiations on skin matrix alterations, human skin fibroblasts were irradiated successively three-fold, at 24 h intervals, with UVA (3x5J/cm2), UVB (3x8mJ/cm2), UVA plus UVB (3x5J/cm2 and 3x8mJ/cm2) and the levels of 92 kDa gelatinase (pro-MMP9), 72 kDa gelatinase (pro-MMP2) and plasma-membrane elastase type protease were determined, following subsequent 24-h culture in 10% serum-containing medium. UV irradiations had only minor influence (1.4-fold increase for UVB) on secreted levels of pro-MMP2 and decreased the amount of plasma membrane elastase produced by cells. It did however, for UVA and UVB alone, induce a significant increase of 66 kDa activated MMP2 production: 2.5- and 1.7-fold respectively. Such enhancement was not observed when combined irradiations were administered. UV exposure possessed a much higher influence on pro-MMP9 secretion by dermal fibroblast enhancing enzyme levels by 2.5-, 6.5- and 5-fold for UVA, UVB and UVA+UVB, respectively.

Adult↗

The rate of fibrinolysis is increased by free retraction of human gingival fibroblast populated fibrin lattices.

We previously demonstrated that human gingival fibroblasts (HGF), but not their dermal counterparts, when seeded in retracting fibrin lattices induced intense fibrinolysis that was observed at the earliest stages of contraction and led to complete matrix degradation by day 7 of culture. Our aim was to examine the influence of mechanical forces in such fibrinolytic processes. HGF were seeded in retracting (R) e.g. free floating or non retracting (NR) e.g. anchored fibrin lattices (FL). Cultures were analysed from day 1-12 by phase contrast microscopy and scanning electron microscopy (s.e.m.). Levels of fibrin degradation products (FDP) and tissue plasminogen activator (tPA) accumulating in culture media were quantified by ELISA. Urokinase (uPA) and gelatinase A (MMP2) were identified by zymographic techniques. At the s.e.m. level, vacuolization around some HGF was noticed at the earliest stages of culture for RFL and complete degradation of lattices occurred at day 7. Formation of lysed matrix cavity was far less intense in NRFL even after 12 days of culture. FDP amounts at day 4 of culture were equal to 79 +/- 14 and 8.5 +/- 0.6 micrograms/10(5) cells for RFL and NRFL, respectively; tPA levels were equal to 5.8 +/- 0.6 (RFL) and 2.1 +/- 0.3 ng/10(5) cells (NRFL) and differences were still evident at day 7. The kinetics of tPA production were identical in either retracting fibrin or collagen lattices. On the contrary, uPA and proMMP2 productions were similar in RFL and NRFL. Isometric forces, but not the matrix support, were responsible for accelerated tPA production and fibrinolysis in HGF populated lattices.

Biomechanical Phenomena↗

Increased expression of gelatinases A and B by skin explants from patients with anetoderma.

The extent of alterations to the elastic fibre network in lesional skin areas of three patients with anetoderma was assessed by quantitative image analysis of tissue sections and compared with morphometric parameters from unaffected sites of the same individuals. In the anetodermic skins pre-elastic fibres were undetectable or extremely rare: the volume fraction (Vv%) occupied by these pre-elastic fibres was 0-0.3%, while in unaffected skins the Vv% occupied by pre-elastic fibres was 0.5-0.8%. A nearly complete absence of dermal elastic fibres in lesional skins from the three patients was evidenced (Vv% = 0.2-0.3%). Organ cultures were performed using explants from skin with or without anetodermic lesions to quantify the expressions of elastase-type proteinases. All tissues from anetodermic lesions expressed proforms of gelatinases A and B and the activated form of gelatinase A; their levels increased with the culture time. In comparison, enzymatic activities on oligopeptide substrates specific for leucocyte elastase and fibroblast plasma membrane-associated metalloelastase were not detected in the conditioned media of any explants at any time of culture from 1 to 5 days. Increased production of progelatinases A and B and activation of progelatinase A could be mainly responsible for the degradation of skin elastic fibres demonstrated in anetodermic skins.

Adult↗

Active and alpha-1 proteinase inhibitor complexed leukocyte elastase levels in crevicular fluid from patients with periodontal diseases.

Human leukocyte elastase is present in large amounts in the crevicular fluid of patients with periodontal disease and was considered as a putative biological marker of the evolution of such diseases. The aim of this work was to measure spectrophotometrically amounts of active elastase (AE) and elastase complexed to alpha 1 proteinase inhibitor (E-alpha 1-PI) in gingival crevicular fluid obtained, from patients suffering from rapidly progressive periodontitis (RPP group) or adult periodontitis (AP group) with different probing depths (3 to 5 mm and > 6 mm). AE and E-alpha 1-PI concentrations were negligible in healthy individuals. AE, but not E-alpha 1-PI, concentration appears to vary significantly with the probing depth in patients suffering either from rapidly progressive or adult periodontitis. No correlations were found between levels of AE and E-alpha 1-PI in the different groups of patients. AE concentration seems to be a marker of periodontal diseases in relation with probing depth.

Adult↗

Tissue origin and extracellular matrix control neutral proteinase activity in human fibroblast three-dimensional cultures.

Remodeling of the extracellular matrix by fibroblasts is an important step in the process of wound healing and tissue repair. We compared the behavior of fibroblasts from two different tissues, dermis and gingiva, in three-dimensional lattices made of two different extracellular matrix macromolecules, collagen and fibrin. Cells were grown in monolayer cultures from normal skin or gingiva and seeded in three-dimensional lattices made of either collagen of fibrin. Photonic and scanning electron microscopy did not reveal any morphological differences between the two types of fibroblasts in both sets of lattices. Both types of fibroblasts retracted collagen lattices similarly and caused only a slight degradation of the collagen substratum. By contrast, when seeded in fibrin lattices, gingival fibroblasts completely digested their substratum in less than 8 days, whereas only a slight fibrin degradation was observed with dermal fibroblasts. The ability of gingival but not dermal fibroblasts to express high levels of tissue plasminogen activators (tPA) when cultured in fibrin lattices was assessed on an immunological basis. Also, deprivation of plasminogen-contaminating fibrinogen preparations or use of tPA inhibitors markedly inhibited both fibrinolysis and retraction rates of fibrin lattices by gingival fibroblasts. Casein-zymography confirmed the intense proteolytic activity induced by fibrin in gingival fibroblasts. It was inhibited by aprotinin and phenyl methylsulfonyl fluoride (PMSF), two non-specific inhibitors of serine proteinases, and by epsilon-amino-caproic acid (epsilon ACA), an inhibitor of plasminogen activators. Monolayer cultures exhibited only trace amounts of caseinolytic activity. Our results demonstrate that the expression of proteinases by fibroblasts is dependent not only on their tissue origin but also on the surrounding extracellular matrix. The intense fibrinolytic activity of gingival fibroblasts in fibrin lattices may explain partially the high rate of healing clinically observed in gingiva.

Adult↗

FGF protection and inhibition of human neutrophil elastase by carboxymethyl benzylamide sulfonate dextran derivatives.

Several derivatized dextrans (DxD) containing defined percentage of carboxymethyl, carboxymethyl benzylamide and carboxymethyl benzylamide sulfonate groups have been shown to stimulate tissue repair in various in vivo models including skin, bone, muscle and cornea. These selected DxD were also shown to mimic heparin or heparan sulfate by their ability to interact with, stabilise and protect the heparin-binding growth factor of the fibroblast growth factor family against trypsin digestion (Tardieu et al., J. Cell. Physiol. 1992; 150: 94). The wound healing action of these DxD was explained by postulating that the endogenously released heparin-binding growth factors could be protected within the wound. To further understand the action of these DxD on tissue repair, we have studied their effect on the human neutrophil elastase (HNE) activity, one of the proteases involved in wound repair. These DxD inhibited HNE in an hyperbolic non-competitive manner. Extent of HNE inhibition by DxD increased with their molecular weight and benzylamide sulfonate substitution levels. One DxD, RGT11, was the best inhibitor (Ki 40 pM) and efficiently inhibited FGF-2 proteolysis by HNE, restoring its growth-promoting activity towards human skin fibroblasts. The data contribute to a better understanding of the wound-healing property and anti-inflammatory activity of these polymers.

Cell Division↗

Increased expression of the Ed-B-containing fibronectin (an embryonic isoform of fibronectin) in human osteoarthritic cartilage.

Fibronectin is non-collagenous protein which accumulates in osteoarthritic cartilage. The presence of fibronectin and its specific isoform containing the B sequence, Ed-B fibronectin (B.Fn), was studied in normal and osteoarthritic human cartilage using immunohistochemical and biochemical assays, with a specific monoclonal antibody. Results showed substantial amounts of B.Fn in osteoarthritic cartilage, especially in the superficial and middle layers. Western blot analysis confirmed the presence of B.Fn with a molecular mass of 220 and 55 kDa. In contrast, in normal cartilage, expression of B.Fn was extremely low. In conclusion, the expression of a specific isoform of fibronectin during the osteoarthritic process suggests that this isoform might have specific functions in extracellular matrix remodelling.

Aged↗

Inhibition of human leukocyte elastase by mineral dust particles.

After isolation, purification, and radiolabeling of elastin from baboon aorta and lung, the rates of hydrolysis of both 3H-labeled elastins by porcine pancreatic elastase (PPE or by human leukocyte elastase (HLE) were compared. PPE (30 nM) degraded aorta and lung elastins at rates of 40 and 75 micrograms/h, respectively, leading to their complete solubilization. In contrast, the low rate of hydrolysis of lung elastin (10 micrograms/h) by HLE was paradoxically accompanied with a fivefold decrease in the Michaelis constant value and became negligible after 1 h of incubation. Moreover, HLE adsorption isotherms showed that 0.87 nmol HLE was adsorbed on 1 mg of aorta elastin vs. 1.30 nmol/mg lung elastin. Also, increasing ionic strength was found to enhance the elastolytic potential of HLE toward lung elastin. Investigations were carried out to explain why baboon lung elastin exhibited low susceptibility to hydrolysis by HLE. Solubilization of lung elastin with PPE produced a residue that exhibited inhibitory capacity toward HLE when either 3H-labeled aorta elastin or succinyl trialanine nitroanilide was used as a substrate. When analyzed by transmission electron microscopy, this residue was found to consist of several mineral dust particles, mainly kaolinite (53%) of environmental origin. The HLE-inhibitory capacities of various mineral or coal mine dust particles were then analyzed. Mineral aluminium-silicate dusts were found to be potent HLE inhibitors: 5 micrograms of either kaolinite or montmorillonite totally abolished the activity of 0.45 micrograms of HLE. All these results allowed us to propose that HLE inhibition by aluminium-silicate dusts may be of importance in the pathogenesis of industrial pneumoconiosis and in opportunistic lung infections.

Animals↗

Proteolytic activity is involved in changes in intrafollicular insulin-like growth factor-binding protein levels during growth and atresia of ovine ovarian follicles.

In the sheep, follicular growth is characterized by both an increase and a decrease in the level of intrafollicular insulin-like growth factor-binding protein-3 (IGFBP-3) and IGFBPs less than 40 kDa (IGFBP-2, -4, and -5), respectively. In contrast, follicular atresia is associated with a decrease and a large increase in levels of IGFBP-3 and IGFBPs less than 40 kDa, respectively. To assess whether intrafollicular proteases are involved in such changes, follicular fluid from follicles of different sizes and degrees of atresia was incubated alone or with pure human IGFBP-3, -4, or -5 or serum (as a source of exogenous IGFBP-2) for 20 h at 37 C. Samples were then analyzed by Western ligand blotting and by immunoblotting using specific antisera. Ovine follicular fluid from different classes of follicles contained proteolytic activity degrading IGFBP-2, -3, -4, and -5. Degradation of IGFBPs was accompanied by the generation of small proteolytic fragments visualized by immunoblotting or after autoradiography using radiolabeled IGFBP-4. Moreover, follicular growth and atresia were characterized by changes in IGFBP proteolytic activity. Indeed, follicular growth (between 2 and 6 mm in diameter) was characterized by 1) a decrease in IGFBP-3 proteolytic activity and 2) a dramatic increase in proteolytic activity degrading IGFBP-4 and, to a lesser extent, IGFBP-2 and -5. Atresia, in contrast, was associated with a strong increase in IGFBP-3 proteolytic activity in small ( < 3-mm diameter) follicles and a decrease in IGFBP-4 and -5 proteolytic activity in large ( > 5-mm diameter) follicles. Regardless of the follicle class, IGFBP proteolytic activity was strongly inhibited by EDTA and 1,10-phenanthroline, but very slightly or not at all inhibited by tissue inhibitor of matrix metalloprotease-1 and-2 and BB-2116 (natural and synthetic inhibitors of matrix metalloproteases, respectively) as well as cysteine and serine proteases inhibitors, with the exception of phenylmethylsulfonylfluoride (1 mM) in atretic follicles. In addition, IGFBP proteolytic activity was dependent on the presence of zinc and calcium chloride. Zymography experiments showed the presence of 72- and 92- to 96-kDa gelatinases in follicular fluid; their levels were dramatically increased during follicular atresia. These results suggest that 1) changes in intrafollicular IGFBP proteolytic activity could be at least partly responsible for the changes in intrafollicular IGFBP levels that occur during follicular growth and atresia in the sheep; and 2) metalloprotease(s) in healthy and atretic follicles as well as serine protease(s) in atretic follicles are involved in IGFBP degradation.

Animals↗

Presence of ED-A containing fibronectin in human articular cartilage from patients with osteoarthritis and rheumatoid arthritis.

OBJECTIVE: To determine whether normal (fetal and adult) and osteoarthritic (OA) and rheumatoid arthritic (RA) cartilage express a specific isoform of fibronectin, the extra domain A (ED-A) containing fibronectin (EDA+Fn). METHODS: Presence of fibronectin (EDA+Fn and native molecule) in cartilage matrix was studied using immunohistochemical assays with specific monoclonal antibodies. Fibronectins were identified by Western blots, in synovial fluids (SF) and cartilage extracts. RESULTS: EDA+Fn was either moderately present in the surface zone or undetectable in normal cartilage, while it was increased in OA cartilage surface. In one OA cartilage sample, EDA+Fn was localized in the matrix distant from the cartilage surface (patches of staining) and its presence was confirmed by immunoblotting. In RA cartilage EDA+Fn was present in the pericellular areas of the different layers. By Western blots, the presence of EDA+Fn was confirmed in OA SF (2/3) and RA SF (3/3) (with different patterns of fragmentation). CONCLUSION: EDA+Fn generally accumulates in the surface zone of OA cartilage, where it may play a role in extracellular matrix remodelling. Its presence was more abundant in SF and in cartilage from patients with RA.

Aged↗

Uncoordinate expressions of type I and III collagens, collagenase and tissue inhibitor of matrix metalloproteinase 1 along in vitro proliferative life span of human skin fibroblasts. Regulation by all-trans retinoic acid.

In vitro human skin fibroblasts aging was characterized by a continuous increase of collagenase mRNA levels. On the contrary, TIMP-1 mRNA level decreased only at late passages (> 65% of proliferative life span). Type I and III mRNA levels showed a high variability depending on cell strains studied. However, type I and III collagen expressions varied parallely. All-trans retinoic acid (RA) decreased collagenase expression and stimulated TIMP-1 expression. Under RA action, high variability in mRNAs levels encoding type I and III collagens was observed with HSF passages. However, RA tended to correct variations in collagens expressions observed along HSF life span.

Cell Division↗

Inhibition by dextran derivatives of FGF-2 plasmin-mediated degradation.

In previous work we have shown that some new regenerating agents (RGTAs), molecules which correspond to some dextran derivatives (DxD) containing defined amounts of carboxymethyl (CM), benzylamide (B) and benzylamide sulfonate (BS) groups, were able to stimulate tissue repair when applied at the site of injury. Based on in vitro studies showing that these DxD could interact and protect heparin binding growth factors (HBGFs), we postulated that DxD could also act in vivo by protecting endogenously released HBGFs against protease degradation. We now present data demonstrating that human plasmin (HP1), one of the known proteases involved in extracellular matrix remodelling and in the local activation of some growth factors is specifically inhibited by some specific DxD. The most efficient compounds for inhibiting the amidolytic activity were substituted by all functions with IC50 at 0.26 microM for RGTA11 (a DxD obtained from a 40,000 Da dextran containing 110% of CM, 2.5% of B and 36.5% of BS units and with IC50 at 1.1 microM for RGTA10 (derived from 10,000 Da dextran and containing 110% of CM, 0% of B and 27.3% of BS). Compounds which were substituted with only one or two functions were less effective. The degradation of FGF-2 by HP1 was analyzed by SDS-PAGE and by measuring its residual growth promoting activity using a bioassay on human skin fibroblasts. In this assay, RGTA11 at a concentration of 1 microM could inhibit by 80-100% FGF-2 degradation induced by HP1 treatment. In conclusion, the inhibitory activity of some DxD towards HP1 as well as the ability of these DxD to protect FGF-2 against this proteinase could partially explain its beneficial influence on extracellular matrix remodelling following tissue injury.

Adult↗

Histomorphometric parameters and susceptibility to neutrophil elastase degradation of skin elastic fibres from healthy individuals and patients with Marfan syndrome, Ehlers-Danlos type IV, and pseudoxanthoma elasticum.

The morphometric parameters of mid-dermal elastic fibres from the skin of four patients with Marfan syndrome, four patients with Ehlers-Danlos syndrome type IV (EDS IV), and two patients with pseudoxanthoma elasticum (PXE) were determined, and compared with those of healthy individuals of a similar age range. The volume fraction occupied by elastic fibres was significantly reduced in Marfan patients compared with normal controls, and this was independent of age. In contrast, it was significantly increased in PXE patients, whereas the volume fraction occupied by skin elastic fibres varied within the EDS IV group. Dermal elastic fibres from patients with Marfan syndrome, EDS IV and PXE are hydrolysed by human neutrophil elastase in a qualitatively and quantitatively different fashion from those from healthy individuals. Marfan syndrome and EDS IV dermal elastic fibres were found to be more resistant to hydrolysis by human neutrophil elastase, but PXE elastic fibres were hydrolysed at a rate similar to elastic fibres from control skin.

Adolescent↗

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.

Animals↗

Growth stimulation of human skin fibroblasts by elastin-derived peptides.

Elastin-derived peptides (kappa-elastin: kappa E, mean molecular mass: 75 kDa), either coated onto plastic dishes or added to culture media (0.26 to 1.33 nM) stimulated the growth of human skin fibroblasts (HSF) strains obtained from different donors and tested at different cell passages (4 to 12). Coated 44.4 micrograms/cm2 insoluble elastin (iE) exhibited the same action; coated iE or kappa E significantly modifies the HSF morphology: after 5-6 days of culture, HSF are more elongated, and at preconfluence state, formation of HSF clusters surrounding iE were observed. Increased 3H thymidine incorporation and proliferative effect of HSF by kappa E (1.3 to 2.2 fold as compared to control cells) was observed after a lag phase period which raised with initial HSF density. Optimal proliferative effect was obtained at kappa E 8.5 10(-10) M, a value close to the dissociation constant (kD = 2.7 10(-10) M) of kappa E to HSF. Valine-glycine-valine-alanine-proline-glycine (VGVAPG), but not valine-glycine-valine (VGV) or Valine-glycine-valine-valine-glycine-alanine (VGVVGA) also significantly stimulated, optimally at 7.0 10(-10) M, HSF proliferation. It was concluded that the stimulatory influence of elastin derived peptides on HSF proliferation was mediated through a binding to plasmalemmal receptor of HSF.

Adult↗

[Elastase-type endopeptidase of fibroblasts. Effect of metalloprotease inhibitors].

Human skin fibroblasts produce in culture an elastase-type metalloendopeptidase which can hydrolyze synthetic elastase-substrate as Suc ala3 pNA and degrade also elastic fibers when injected in the dermis or deposited on cryostat-skin sections [3-8]. Here we describe further characterization of this enzyme activity using metallo-enzyme inhibitors as well as specific inhibitors of known Zn-endopeptidases such as angiotensin converting enzyme and enkephalinase. Among the metal complexing agents tested only EDTA and o-phenanthrolin could inhibit the elastase-type activity of fibroblasts, other known metal complexing substances capable of reacting with Zn (2,2' dipyridyl, diethyl dithiocarbamate and other metal chelators) were ineffective as was also lisinopril, an ACE-inhibitor [13]. Phosphoramidon and retrothiorphan, specific enkephalinase inhibitors [12] did strongly inhibit the elastase type activity of human skin fibroblasts (IC50 10(-8) M). Ethanol at conc-s used to dissolve organic, water insoluble inhibitors (50-100 microliters/ml) strongly inhibited the enzyme. It appears that the metal prosthetic group of fibroblast elastase (presumably, Zn) is not directly accessible to several of the low M. Wt complexing agents. The efficiency of enkephalinase inhibitors suggest a possible relationship between this enzyme and fibroblast-elastase.

Adult↗

Interaction of tumour cells with elastin and the metastatic phenotype.

It is now well established that the interaction of tumour cells with elastin is important during invasion and metastasis. This is due to the fact that the elastin receptor complex is widely expressed by tumour cells and is overexpressed in highly metastatic variants. There is evidence that the elastin receptor complex is associated with a signal system involving G proteins, phospholipase C, the phosphoinositol cycle and protein kinase C. Therefore, activation of the elastin receptor system results in activation of protein kinase C-dependent cellular processes such as enzyme secretion and migration. Accordingly, soluble elastin can be used in vivo to interfere with tumour cell dissemination into elastin-rich tissues such as lung, skin or blood vessels. The importance of elastin-tumour cell interactions is emphasized by the observation that the 67 kDa receptor for laminin may well be identical to the 67 kDa elastin receptor of the elastin receptor complex. Interference with the function of this receptor system by the use of both laminin peptides and elastin ligands may provide the basis for a novel and more powerful antimetastatic intervention.

Amino Acid Sequence↗