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F X Maquart

Publications and source records attributed to F X Maquart.

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↗
PubMed1999

Triterpenes from Centella asiatica stimulate extracellular matrix accumulation in rat experimental wounds.

Titrated Extract from Centella asiatica (TECA) is a drug which has been used for many years in Europe for the treatment of wound healing defects. It is a reconstituted mixture of 3 triterpenes extracted from the plant, asiatic acid, madecassic acid and asiaticoside. In this report, we studied the effects of TECA and its separated components in the wound chamber model described by Schilling et al. Stainless steel wound chambers were surgically inserted under the skin of rats and received serial injections of either TECA or its purified components. Chambers were collected at days 7, 14, 21 or 28 for biochemical analysis or histological examination. TECA-injected wound chambers were characterized by increased dry weight, DNA, total protein, collagen and uronic acid contents. Peptidic hydroproline was also increased, showing an increased remodeling of the collagen matrix in the wound. The 3 purified components of TECA were all able to reproduce the effects of the complete drug, with some differences depending on the product. Asiatic acid and asiaticoside were the most active of the 3 triterpenes. Asiaticoside exerted a preferential stimulation of collagen synthesis and was active at low doses only. In addition to collagen, the 3 components were also able to stimulate glycosaminoglycan synthesis.

Animals↗
PubMed1999

[Regulation of cell activity by the extracellular matrix: the concept of matrikines].

The activity of connective tissue cells is modulated by a number of factors present in their environment. In addition to the soluble factors such as hormones, cytokines or growth factors, cells also receive signals from the surrounding extracellular matrix (ECM) macromolecules. Moreover, they may degrade the ECM proteins and liberate peptides which may by themselves constitute new signals for the surrounding cells. Therefore, an actual regulation loop exists in connective tissue, constituted by peptides generated by ECM degradation and connective tissue cells. The term of "matrikine" has been proposed to designate such ECM-derived peptides able to regulate cell activity. In this review, we summarize some data obtained in our laboratory with two different matrikines: the tripeptide glycyl-histidyl-lysine (GHK) and the heptapeptide cysteinyl-asparaginyl-tyrosyl-tyrosyl-seryl-asparaginyl-serine (CNYYSNS). GHK is a potent activator of ECM synthesis and remodeling, whereas CNYYSNS is able to inhibit polymorphonuclear leukocytes activation and decrease the invasive capacities of cancer cells.

Amino Acid Sequence↗
PubMed1998

Uridine diphosphoglucose dehydrogenase regulates proteoglycan expression: cDNA cloning and antisense study.

Using a reverse-transcriptase-polymerase chain reaction approach human and murine UDPG-dehydrogenase (GDH) was cloned from fibroblast mRNAs. Human enzyme is 97% and 27% identical with its murine and E. coli orthologs. Murine mRNA of 3.1 kb size is expressed in all the tissue studied at a level independent of glyceraldehyde-3-phosphate dehydrogenase (GADPH) mRNA. In human fibroblast in vitro, 2 GDH transcripts were observed. They were expressed proportionally to GAPDH. The simple pattern of human GDH Southern blotting suggests a single copy gene. An antisense oligonucleotide directed to the ATG region of the human enzyme inhibited 35S-sulphate incorporation into extracellular macromolecules, especially proteoglycans. These data indicate that GDH expression may regulate proteoglycan synthesis in the cells.

Amino Acid Sequence↗
PubMed1998

A comparative study of cryogenic lesions in organ-cultured human skin and in reconstituted human skin equivalent.

Cryosurgery is a technique that is widely used in the treatment of cutaneous tumors. However, there are still features of healing in cryosurgery wounds that are incompletely understood and necessitate further study. In the present paper, we describe two in vitro models that were developed to study the initial stages of development of the cryolesion: reconstituted human skin and organ-cultured human skin. Cryolesions were generated in both models by applying a 2-mm-diameter cryoprobe at -196 degrees C for 35 s. Histological features were analyzed at days 0, 3, 5, and 14 following cryotreatment and showed epidermal detachment and keratinocyte necrosis very close to the findings reported in vivo. Results were similar in the two models. Gross alteration of the dermal architecture was noticed beneath the cryolesion, particularly in the reconstituted skin model. Cell proliferation was investigated at days 0, 3, and 5 by [3H]thymidine incorporation and Ki-67 antigen immunolabeling. In the case of organ-cultured skin, a significant increase in keratinocyte and fibroblast proliferation was observed at day 3, compared to the controls. At day 5, a return to the basic level was noticed. This was not observed in the reconstituted skin model at either day 3 or day 5. These data led us to propose that organ-cultured skin may be a useful model for evaluating the response of human skin to freezing; reconstituted skin was not adequate for this purpose.

Cryosurgery↗
PubMed1998

Morphometric studies of collagen and fibrin lattices contracted by human gingival fibroblasts; comparison with dermal fibroblasts.

Cell shape variations and substratum re-organization during contraction of floating collagen and fibrin lattices seeded with human gingival fibroblasts were determined by computerized image analysis of light and scanning electron microscopic images. Data were compared with those obtained with lattices populated with human dermal fibroblasts. The extent of collagen lattice contraction was similar with both cell types, resulting in a two-fold decrease in the area fractions occupied by collagen fibers. Fibroblasts exhibited a rounded shape (form factors equal to 0.8 and 0.7 for gingival and dermal cells, respectively) at day 1 of culture; they possessed a more elongated appearance (with form factors equal to 0.3 and 0.15 for gingival and dermal cells, respectively) at day 7. Continuous (gingival) and discontinuous (dermal) layers of cells were evidenced at the cortex of lattices. Contractions were associated with a significant reduction of the diameters of collagen fibers. Re-organization of substratum, as analyzed by the "Rose of Directions" technique, was evidenced only at the vicinity of filopodia where fibers ran parallel to these protrusions. Several lysed matrix cavities were observed when fibrin lattices were populated with gingival but not dermal fibroblasts at day 5 of culture. Although cells in fibrin lattices exhibited morphometric parameters comparable with those in collagen lattices, no fibroblast layers could be demonstrated at gel peripheries. Fibrin matrices consisted of an isotropic network of entangled fibrin filaments from the start of culture, and only a slight reduction of the diameters of fibrin fibers could be evidenced in dermal fibroblast-populated lattices. Fibrinolysis at the vicinity of gingival fibroblasts led to an entire re-organization of substratum toward the formation of larger fibers. The differential behavior of gingival vs. dermal fibroblasts inside fibrin but not collagen matrices could therefore partly explain the increased rate of remodeling of gingiva as compared with dermis.

Adult↗
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↗
PubMed1997

Antagonistic effects of interferon-gamma and interleukin-4 on fibroblast cultures.

A major characteristic of scleroderma (SSc) fibroblasts is an increased biosynthesis of extracellular matrix macromolecules that could be linked to impaired regulation by cytokines. We investigated the effects of two cytokines from T lymphocytes, interleukin-4 (IL-4) and interferon-gamma (IFN-gamma), on normal and scleroderma fibroblast cultures. In both types of fibroblasts, IL-4 strongly stimulated collagen synthesis, whereas IFN-gamma was a potent inhibitor. The effects of these cytokines were localized at the pre-translational level, and both mRNA steady-state level and protein synthesis were equally affected. SSc fibroblasts responded to IL-4 and IFN-gamma as well as normal fibroblasts. When fibroblasts were incubated with combinations of both cytokines, IFN-gamma completely suppressed the stimulation of collagen gene expression induced by IL-4. Northern blot and western blot analyses demonstrated that IFN-gamma induced a rapid and strong decrease in the expression of the IL-4 receptor-alpha by fibroblasts. This effect might explain the antagonistic effects of IFN-gamma on the IL-4-dependent enhancement of collagen synthesis. Thus, our data suggest that the alteration of collagen production in scleroderma fibroblasts does not depend on an altered sensitivity of these cells to stimulatory or inhibitory cytokines but is more likely the consequence of an imbalance in the local production of autocrine or paracrine regulatory factors.

Cell Division↗
PubMed1996

Modulation of protein synthesis by extracellular matrix: potential involvement of two nucleolar proteins, nucleolin and fibrillarin.

Fibroblasts cultivated in a collagen matrix exhibit a large decrease in the synthesis of most proteins, depending on transcriptional and posttranscriptional controls. We have previously shown that ribosomal RNA content and half-life were decreased in collagen lattice cultures. Here, we cultivated human dermal fibroblasts in monolayers and in lattices and studied by competitive RT-PCR analysis the expression of the nucleolar proteins nucleolin and fibrillarin, two key factors in ribosome processing and association. Nucleolin expression was found increased, and fibrillarin expression decreased, in collagen-lattice vs monolayer-cultured fibroblasts, with some variability according to the strains (+25 to +250% and -40 to -60%, respectively). These data suggest that a possible trouble of the association between neosynthesized rRNA and nucleolar proteins is, at least partly, responsible for the inhibition of protein synthesis induced by the extracellular matrix.

Cells, Cultured↗
PubMed1996

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↗
PubMed1996

Alteration of matrix macromolecule synthesis by fibroblasts from a patient with pachydermoperiostosis.

Pachydermoperiostosis (primary hypertrophic osteoarthropathy) is a very rare genetic disease characterized by pachydermia, periostosis, arthralgia, and finger clubbing. Its pathophysiology is still unclear, but previous studies have reported connective tissue hypertrophy in the skin of these patients. We investigated the synthesis of collagen, fibronectin, and proteoglycans by fibroblasts from affected and unaffected skin from one patient with pachydermoperiostosis and four normal donors. We found that collagen synthesis was largely decreased in fibroblasts from the diseased skin, whereas the synthesis of the small dermatan-sulfate-containing proteoglycan decorin strongly increased. Fibroblasts from the unaffected skin of the patient exhibited syntheses of these macromolecules similar to control fibroblasts from healthy donors. Northern blot and dot blot analyses showed decreased pro alpha 1 (I) collagen in patient's affected and unaffected skin fibroblasts whereas increased decorin mRNA levels were found in fibroblasts from the patient's affected skin. No change in cell proliferation was observed. These data demonstrate an alteration of fibroblast biosynthetic activity in the skin lesions of pachydermoperiostosis, which may be responsible, at least in part, for the patient's phenotype.

Adult↗
PubMed1996

Expression of interleukin-4 in scleroderma skin specimens and scleroderma fibroblast cultures. Potential role in fibrosis.

BACKGROUND: Scleroderma (systemic sclerosis) is a fibrotic disease characterized by an uncontrolled tissular accumulation of collagen. Several cytokines have been implicated in the fibroblast activation leading to fibrosis. For instance, we have previously demonstrated that interleukin-4 (IL-4) is a potent activator of collagen synthesis in fibroblast cultures. In this study, using immunocytochemical methods and in situ hybridization, we investigated the expression of IL-4 in normal and scleroderma skin and fibroblast cultures. OBSERVATIONS: Immunocytochemical studies with anti-IL-4 antibody were performed on biopsy specimens from 9 patients with normal skin and 11 patients with scleroderma. The label was intense or strong in 8 of the 11 scleroderma skin specimens, whereas it was negative or faint in 8 of the 9 normal skin specimens (P < .01). In situ hybridization demonstrated a significant increase of the number of IL-4 messenger RNA grains in scleroderma skin compared with normal skin (3.1 +/- 1.5 [mean +/- SD] vs 0.8 +/- 0.7; P < .001). A strongly positive labeling with the anti-IL-4 antibody was found in the 4 scleroderma fibroblast cultures, whereas it was negative in the 5 fibroblast control cultures (P < .05). CONCLUSIONS: Our results demonstrate that IL-4 is strongly expressed in the dermis of a large majority of patients with scleroderma and might be synthesized by scleroderma fibroblasts. We suggest that IL-4 is one of the cytokines implicated in the early steps of the fibrotic process.

Adult↗
PubMed1995

Stimulation of sulphated glycosaminoglycan and decorin production in adult dermal fibroblasts by recombinant human interleukin-4.

Interleukin-4 (IL-4) is a pleiotropic cytokine expressed by inflammatory cells. Previous work from our laboratory has shown that it stimulates collagen synthesis in fibroblasts. Here we report the effects of recombinant human IL-4 on glycosaminoglycan (GAG) and proteoglycan synthesis in normal dermal fibroblasts from adult donors. IL-4 (10 and 100 units/ml) induced a dose-dependent increase of [3H]glucosamine and [35S]sulphate incorporation into total GAGs. The analysis of the different GAG fractions indicated the enhanced synthesis of dermatan/chondroitin sulphates. IL-4 had no effect on hyaluronan synthesis. The increase of sulphated GAG synthesis was correlated with an increase of proteoglycans in the culture medium. Decorin was identified as the major chondroitin/dermatan sulphate-containing proteoglycan in the culture medium of fibroblasts. Its synthesis was strongly stimulated by IL-4. Both the core-protein synthesis and mRNA expression were enhanced, indicating that the cytokine acted, at least in part, at the pre-translational level. These results indicate that IL-4 is able to modulate not only collagen, but also proteoglycan, production by human fibroblasts. Their implications in physiopathological processes such as wound healing or fibrosis is suggested.

Adult↗
PubMed1994

The effect of different collagens and of proteoglycan on the retraction of collagen lattice.

The effect of various collagens and proteoglycan on the formation and retraction of collagen lattices was tested. The most rapid aggregation of collagen molecules was observed by the use of the least cross-linked collagen fractions (ie pepsin-digested calf skin collagen type I). Lattices formed with more cross-linked collagens (acid soluble collagen-ASC, type III) contracted slowly and less intensively. Unpurified pepsinized cartilage extract containing collagen types II, IX and XI, some glycoproteins and proteoglycans formed lattices rather well. On the contrary, purified collagen type II as well as polymeric collagen (solubilized by denaturing conditions) did not form lattices at all. The lattice formation and retraction was intensified by addition of proteoglycan into the culture medium. The authors suggest that the kinetics of the lattice formation and retraction depends on the amount of collagen cross-links and the concentration of proteoglycan in the culture medium.

Collagen↗
PubMed1994

[Pachydermoperiostosis. An ultrastructural study].

BACKGROUND: Pachydermoperiostosis (PDP) is a rare genetically determined disease belonging to the group of hypertrophic osteoarthropathies. Its aetiopathogenesis remains unclear. Most hypotheses favour an exogenous stimulation of fibroblasts. METHODS: A clinically typical patient with PDP was studied by electron microscopy with particular reference to the dermis and its cellular constituents. Fibroblasts from involved skin were cultured and studied in comparison with control cells. RESULTS: Remarkable modifications of the structure of the dermis were observed, encompassing irregular caliber of collagen fibres, extracellular deposits of microfibrils and of amorphous granular substance corresponding to the Alcian blue positive deposits seen by conventional histochemistry. The in vitro growth of fibroblasts was normal. CONCLUSION: Authors reviewed aetiopathogenic hypotheses. Our data suggest a genetically determined alteration of extracellular matrix production by fibroblasts as a possible explanation for the development of PDP.

Adult↗
PubMed1994

[Interleukin-4: from B-lymphocyte to fibroblast].

Interleukin-4 (IL-4) has been characterized in 1982 by its ability to induce the proliferation of anti-IgM stimulated B-lymphocytes and IgG1 secretion by these same cells after activation by lipopolysaccharide. It's activity on B-cells explain that it received the former names of B-Cell Growth Factor-1 (BCGF-1) or B-Cell Stimulatory Factor-1 (BSF-1). More recent works have shown that IL-4 exerts pleiotropic effects on a large number of cells. Particularly, it is able to activate the production of extracellular matrix components by fibroblasts. The aim of the present paper is to review main data about this cytokine, with a particular emphasis on its role on the regulation of connective tissue cell activities and on its possible implication in pathophysiological events such as fibrosis, wound healing, and tumor invasion.

Arthritis, Rheumatoid↗