Biomedical subjects

H Emonard

Publications and source records attributed to H Emonard.

At least 37 records · Page 2Linked to original sources

PubMed1999

Expression and activation of matrix metalloproteinases in wounds: modulation by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+.

We investigated the expression and activation of matrix metalloproteinases in a model of experimental wounds in rats, and their modulation by glycyl-L-histidyl-L-lysine-Cu(II), a potent activator of wound repair. Wound chambers were inserted under the skin of Sprague-Dawley rats and received serial injections of either 2 mg glycyl-L-histidyl-L-lysine-Cu(II) or the same volume of saline. The wound fluid and the neosynthetized connective tissue deposited in the chambers were collected and analyzed for matrix metalloproteinase expression and/or activity. Interstitial collagenase increased progressively in the wound fluid throughout the experiment. Glycyl-L-histidyl-L-lysine-Cu(II) treatment did not alter its activity. Matrix metalloproteinase-9 (gelatinase B) and matrix metalloproteinase-2 (gelatinase A) were the two main gelatinolytic activities expressed during the healing process. Pro-matrix metalloproteinase (pro-form of matrix metalloproteinase)-9 was strongly expressed during the early stages of wound healing (day 3). In the wound fluid, it decreased rapidly and disappeared after day 18, whereas in the wound tissue, matrix metalloproteinase-9 expression persisted in the glycyl-L-histidyl-L-lysine-Cu(II) injected chamber until day 22. Pro-matrix metalloproteinase-2 was expressed at low levels at the beginning of the healing process, increased progressively until day 7, then decreased until day 18. Activated matrix metalloproteinase-2 was present in wound fluid and wound tissue. It increased until day 12, then decreased progressively. Glycyl-L-histidyl-L-lysine-Cu(II) injections increased pro-matrix metalloproteinase-2 and activated matrix metalloproteinase-2 during the later stages of healing (days 18 and/or 22). These results demonstrate that various types of matrix metalloproteinases are selectively expressed or activated at the various periods of wound healing. Glycyl-L-histidyl-L-lysine-Cu(II) is able to modulate their expression and might significantly alter wound remodeling.

Animals↗

PubMed1998

Regulation of matrix metalloproteinase-2 (gelatinase A, MMP-2), membrane-type matrix metalloproteinase-1 (MT1-MMP) and tissue inhibitor of metalloproteinases-2 (TIMP-2) expression by elastin-derived peptides in human HT-1080 fibrosarcoma cell line.

Soluble kappa-elastin peptides were shown to stimulate the expression of MMP-2 (but not MMP-9) by human fibrosarcoma HT-1080 cells, both at the protein and mRNA levels; maximal effect being observed at a concentration of 25 microg/ml of kappa-elastin. The stimulatory effect could be reproduced using Val-Gly-Val-Ala-Pro-Gly (VGVAPG) peptide, an elastin-derived hydrophobic hexapeptide which represented the elastin receptor binding sequence of tropoelastin. Furthermore, treatment of cells with lactose (30 mM), which dissociated 67-kDa elastin binding protein (EBP) from cell surfaces, completely abolished this effect, suggesting that the elastin receptor could mediate such a response. Using a specific monoclonal antibody, 67-kDa EBP was detected in HT-1080 membrane preparations by Western immunoblotting. Following treatment with 25 microg/ml kappa-elastin or 200 microg/ml VGVAPG, increased levels of the active 62-kDa form of MMP-2 were found in HT-1080 cell extracts. Stimulation of MT1-MMP mRNA expression by treatment with elastin-derived peptides (EDPs) was shown by competitive polymerase chain reaction (PCR). A reverse zymography analysis revealed that EDPs also stimulated TIMP-2 (but not TIMP-1) production by HT-1080 cells. Competitive PCR confirmed increased TIMP-2 mRNA expression by such treatment. These results suggest that occupancy of the 67-kDa elastin receptor by elastin-derived peptides enhanced both expression and activation of proMMP-2 and consequently, could promote the invasive/metastatic ability of tumor cells expressing this receptor.

Elastin↗

PubMed1997

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↗

PubMed1994

Role of matrix, fibroblasts and type IV collagenases in tumor progression and invasion.

We have studied the role of the extracellular matrix and host cells in tumor progression and tumor invasion. Our results emphasize the importance of tumoral cell-host cell interactions during this process. Addition of human fibroblasts and/or basement membrane components to human mammary adenocarcinoma cells, when injected into athymic nude mice, results in an increase of take and growth rate of the tumors. Peritumoral extracellular matrix is remodeled through multiple mechanisms: overproduction of matrix components by fibroblasts, enhanced fibroblasts proliferation, modulation of interstitial collagenase production by fibroblasts and retraction of the matrix by tumoral cells. The degradation of basement membranes during the metastatic process is often associated with the secretion of proteolytic enzymes. The 72 kDa type IV collagenase, a metalloproteinase, can be produced by some tumoral cells. However, it appears also to be secreted by peritumoral stromal fibroblasts under the influence of tumoral cells. We have demonstrated the existence of a binding site for this enzyme on the membrane of mammary tumoral cells. These results suggest a cooperation between tumor cells and fibroblasts during basement membrane destruction.

Animals↗

PubMed1993

Extensive deposition of basement membrane by tumours: a prognostic factor? A reappraisal.

A loss of the continuous linear deposit of basement membrane around invasive carcinomas has been suggested to correlate with their increased invasiveness. In contrast, extensive basement membrane deposition would represent a more favourable prognosis. The Engelbreth-Holm-Swarm (EHS) tumour, a transplantable neoplasm, is widely used for its ability to synthesize and deposit large amounts of basement membrane components. We have evaluated the metastatic potential of this neoplasm 2 months after subcutaneous inoculation. Histological examination of lung sections revealed the presence of numerous metastatic foci. The metastatic cells retained their organization into clusters surrounded by extracellular matrix. Both the 72 kDa and the 92 kDa type IV collagenases were detected by zymography in Triton or urea extract (matrigel) of primary tumour. These results cast doubt on the hypothesis that the extensiveness of basement membrane deposition might always be of prognostic value by being inversely correlated with the degree of invasiveness of a carcinoma.

Animals↗

PubMed1992

Interleukin-6 does not regulate interstitial collagenase, stromelysin and tissue inhibitor of metalloproteinases synthesis by cultured human fibroblasts.

We have examined the effect of interleukin-6 (IL-6) on the synthesis of matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases (TIMP) by human skin fibroblasts, both at protein and messenger RNA levels. IL-6 did not modulate the production of MMPs and TIMP. Furthermore IL-6 did not modify the stimulatory effect exerted by interleukin-1 (IL-1) on the expression of MMPs and TIMP. These results strongly suggest that IL-6 is not involved in the extracellular matrix breakdown, either directly by acting on cell production of MMPs or TIMP, or indirectly by modulating the effect of IL-1 on the synthesis of MMPs and TIMP.

Cells, Cultured↗

PubMed1991

Tissue hyperfibrils are degraded forms of collagen fibrils. An ultrastructural study employing enzymatic treatments.

To elucidate the origin of collagen hyperfibrils, we have ultrastructurally investigated the development of collagen fibrils after in situ treatment of liver tissue sections by different proteolytic enzymes. After treatment, collagen fibrils were largely disorganized within the same fibril bundle. A wide range in diameters was observed. Hyperfibrils, which correspond to those fibrils with the largest diameters and having a flower-like section, were present. On the basis of these results, we can suggest that hyperfibrils reflect breakdown states of collagen fibrils.

Actin Cytoskeleton↗

PubMed1990

Collagen-mediated dispersion of NBT-II rat bladder carcinoma cells.

During metastatic spread, locomotion mediated by extracellular matrix components of basement membranes and connective tissues has been invoked as a prerequisite to invasion. We studied the interactions of the rat bladder carcinoma cell line NBT-II with fibronectin, laminin, and collagens (types I, III, IV, and V). They all promoted cell attachment and spreading. To analyze their scatter potential, we studied epithelial outgrowth and/or peripheral cell dispersion from tumor aggregates. All matrix components allowed partial collapse of the aggregate and the appearance of a cellular monolayer forming a halo around the aggregate. No peripheral cell dispersion occurred on fibronectin and laminin. Collagens (especially types I and III) promoted the dispersion of peripheral NBT-II cells with various speeds of locomotion, as revealed by time-lapse videomicroscopy. With the exception of cells at the periphery on collagens, cells inside the halo did not exchange neighbors, migrated transiently as an epithelial sheet during halo formation, and finally remained stationary. These effects were reproduced with NBT-II tumor fragments obtained from nude mice. Tumor cells were linked together with desmosomes (as revealed by immunoreactivity against desmoglein). Migration on collagens correlated with the mechanical disruption of intercellular contacts and consequently with the progressive disappearance of desmoglein immunoreactivity. Immunofluorescence studies also revealed a reduced expression of the epithelium-specific cell adhesion molecule liver cell adhesion molecule after contact with collagens. These results suggest that direct interactions with collagens may favor single cell infiltration by bladder carcinoma.

Animals↗

PubMed1990

Reconstituted basement membrane matrix stimulates interstitial procollagenase synthesis by human fibroblasts in culture.

Synthesis of interstitial collagenase by human fibroblasts was compared when cultured on plastic, in the presence or absence of soluble laminin, on a type I collagen gel and on a gel of basement membrane components (matrigel). Fibroblasts cultured on matrigel or on type I collagen gel displayed an increase in the steady-state levels of mRNA for interstitial procollagenase that was proportional to its enzymatic activity. Laminin, the main component of matrigel, had no effect on the interstitial collagenase synthesis by fibroblasts. We suggest that matrigel, which stimulates the interstitial collagenase production at a transcriptional step, could regulate the catabolic potential of fibroblasts.

Basement Membrane↗

PubMed1990

Plasminogen activator activity increases during reversal of hepatic fibrosis in murine schistosomiasis.

After specific chemotherapy, granulomatous fibrosis undergoes a marked reversal in liver of Schistosoma mansoni-infected mice. We have previously shown that this fibrosis reversal was related to a high proportion of the active form of the interstitial collagenase. In vitro, plasmin has been described as a physiological activator of interstitial procollagenase. Moreover, plasmin itself degrades directly matrix components such as proteoglycans and fibronectin. We have thus followed the course of the plasminogen activator, which converts plasminogen zymogen to plasmin, in liver of S. mansoni-infected mice treated with praziquantel, as schistosomicidal drug. It was found that plasminogen activator activity in the liver increases rapidly until 5 days after treatment as compared to nontreated infected mice and then diminishes gradually. Increased plasminogen activator activity appears to be one of initial events leading to this fibrosis reversal.

Animals↗

PubMed1990

Type IV and interstitial collagenolytic activities in normal and malignant trophoblast cells are specifically regulated by the extracellular matrix.

Type IV and interstitial collagenolytic activities were compared in human malignant and normal trophoblast cells cultured on plastic, in presence or absence of laminin in solution, on matrigel (a gel of basement membrane components) and on type I collagen gel. Laminin highly stimulated the type IV collagenolytic activity but not the interstitial collagenolytic activity, in malignant trophoblast cells. This glycoprotein had no effect on the interstitial collagenolytic activity and doubled the type IV collagenolytic activity in normal trophoblast cells. Thus malignant trophoblast cells produce preferentially the enzyme able to degrade basement membrane when in contact with laminin, and the enzyme able to degrade interstitial collagen fibers when cultured on type I collagen. On the contrary, type I collagen gel and matrigel equally increased both type IV and interstitial collagenolytic activities by normal trophoblast cells. Interactions of tumor trophoblast or normal trophoblast cells with the extracellular matrix result thus in distinct stimulations of collagenolytic activities. Increased production of type IV collagenolytic activity upon exposure to laminin appears to be specific of the metastatic phenotype.

Animals↗

PubMed1990

Matrix metalloproteinases. A review.

Matrix metalloproteinases constitute the major proteolytic enzyme group degrading the extracellular matrix components. They are involved in the remodeling of the connective tissue during normal biological processes. Their abnormal expression leads to pathological situations.

Animals↗

PubMed1990

Human liver fibroblast capacity for synthesizing interstitial collagenase in vitro.

si e s------------------------ABSTRACT------------------------- P4 initiates specifically the degradation of interstitial collagen types I-III. This enzyme is thus directly involved in the remodeling of the connective matrix. Fibroblasts are considered as the major source of interstitial collagenase in many tissues. However previous studies shown that liver fibroblasts did not spontaneously produce the enzyme. We have thus measured the steady-state levels of mRNA for interstitial procollagenase and quantified interstitial collagenase activity in cultured human liver fibroblasts, in presence or not of interleukin-1 or tumor necrosis factor. We demonstrate that human liver fibroblasts have the capacity for producing interstitial collagenase and that this production is regulated at a transcriptional step. We suggest that the liver fibroblast could represent a key cell for therapeutic strategies of fibrosis reversal.

Collagenases↗

PubMed1989

Active and latent collagenase activity during reversal of hepatic fibrosis in murine schistosomiasis.

In schistosomiasis mansoni, eggs trapped in portal venules of the liver induce a granulomatous inflammatory reaction and subsequently fibrosis. Upon specific schistosomicidal treatment, however, fibrosis undergoes a marked reversal. The features of this process as regards collagen metabolism were examined in mice using praziquantel as the schistosomicidal drug, which was given 68 days after infection. It was found that collagenase activity in the liver, for both latent and active forms, increases rapidly until 5 days after treatment as compared to nontreated infected mice and then diminishes gradually. The hydroxyproline content in liver and (24-hr) urine are also modified, their values decreasing progressively up to 72 days after treatment without, however, reaching values observed in normal mice. Worm death appears to be the triggering stimulus of these events.

Animals↗

PubMed1989

Interstitial collagenase (MMP-1), gelatinase (MMP-2) and stromelysin (MMP-3) released by human fibroblasts cultured on acellular sarcoid granulomas (sarcoid matrix complex, SMC).

We studied collagenase, gelatinase and stromelysin syntheses by human fibroblasts cultured on three models of tridimensional matrix: native collagen sponge, native collagen complexed with glycosaminoglycans sponge, and acellular sarcoid matrix complex prepared from human sarcoid granulomas. Collagenase and stromelysin biosyntheses were differently stimulated according to culture conditions. Fibroblasts secreted a same amount of collagenase or stromelysin when cultured on collagen and collagen-glycosaminoglycans sponges, while collagenase and stromelysin secretions were widely amplified when cultured on sarcoid matrix complex. In contrast, gelatinase production was equally induced by the three culture conditions. In the different culture conditions on tridimensional matrix, the three matrix metalloproteinases were synthesized in a latent form. Thus, the sarcoid matrix complex stimulated the release of collagenase and stromelysin by fibroblast, but did not stimulate the release of gelatinase. This suggests that collagenase and stromelysin syntheses are co-regulated while gelatinase production is controlled by a distinct mechanism.

Cells, Cultured↗

PubMed1988

Distribution and synthesis of type I and type III collagens in developing mouse molar tooth root.

The distribution and synthesis of type I and type III collagens in the mouse molar tooth root have been investigated by correlating light and electron immunohistochemical data. Purified rabbit antibodies were raised against mouse type I and type III collagens and indirect immunoperoxidase procedures were used. In these conditions, predentin, pre-bone, and pre-acellular cementum were intensely immunostained for type I collagen. Both optic and ultrastructural data confirmed the presence of type I collagen at the epithelio-mesenchymal junction, but Hertwig's basement membranes remained unlabelled. The odontoblasts including the short polarized ones, osteoblasts, some cells of pulp mesenchyme and the perifollicular cells possessed type I collagen immunoreactivity in the rough endoplasmic reticulum (RER), Golgi complex and the secretory vesicles. Type III collagen immunoreactivity was strong in the perifollicular mesenchyme, light in the pulp mesenchyme and absent from the epithelio-mesenchymal junction, the predentin, pre-bone and pre-acellular cementum. Intracellular immunolabelling was detected at the ultrastructural level in the perifollicular cells by a faint homogeneous peroxidase deposit in the RER cisternae. Finally, these results, compared with previous biochemical and morphological data, represent the first dynamic aspect of collagens distribution and synthesis in the mouse molar root development. In terms of cell differentiation, our data also suggest that type III collagen synthesis does not occur during the odontoblast process of differentiation.

Animals↗

PubMed1988

Antagonistic effects of laminin and fibronectin in cell-to-cell and cell-to-matrix interactions in MCF-7 cultures.

During morphogenesis, tumor progression and metastasis, cell adhesion, dissociation, and migration result from a complex balance between cell-to-cell and cell-to-matrix interactions. Two different organization patterns of MCF-7 cells were induced by different extracellular matrix proteins. When plated on plastic or polymeric type I collagen gel used as a model of interstitial matrix, MCF-7 cells spread and grew in monolayer. When cultured on a solid gel of basement membrane (BM) proteins (85% laminin) used as a model of BM, cells formed clusters attached to the matrix. Matrix proteins regulated these two types of cell organization by preferentially promoting cell-to-cell or cell-support interactions. On plastic in the presence of soluble laminin or on laminin-coated dishes, cells also formed clusters. Addition of soluble fibronectin induced spreading of the cells, suggesting that laminin and fibronectin have competitive antagonistic effects on MCF-7 cell morphology. Antilaminin antibodies inhibited cluster formation and attachment, emphasizing the important role of this glycoprotein not only in promoting cluster attachment but also in cell-to-cell contact formation. Such effects of extracellular matrix proteins could play significant roles in tumor progression and metastasis.

Breast Neoplasms↗

PubMed1988

Thymic extracellular matrix in myasthenia gravis. II. Immunohistochemical evidence for increased type I collagen degradation.

By immunohistochemistry, we studied the breakdown of type I collagen in frozen sections of normal and hyperplastic (myasthenia gravis-associated) human thymuses. This analysis was carried out using a specific polyclonal antibody directed against the alpha 2-CB(3,5) peptide, a degradation product of type I collagen. In the normal thymus, virtually no labeling was observed within thymic septae or intralobular regions. In contrast, bright fluorescent staining was consistently detected in myasthenia gravis-associated hyperplastic thymuses. Such immunoreactivity was found not only in septal regions but also in the intralobular connective tissue meshwork that exists in these thymuses. Our results represent further evidence for a defect in extracellular matrix metabolism in hyperplastic thymuses, which may be related to the abnormal intrathymic penetration of B cells, known to occur in this disease.

Adolescent↗