Biomedical subjects

C Mauch

Publications and source records attributed to C Mauch.

At least 55 records · Page 3Linked to original sources

PubMed1992

Increased adhesion of fibroblasts from patients with scleroderma to extracellular matrix components: in vitro modulation by IFN-gamma but not by TGF-beta.

A characteristic feature of systemic scleroderma is fibrosis of the skin and eventually of internal organs resulting from an overproduction of collagen and other connective tissue components by the resident fibroblasts. The balance between the cells and the amount of the surrounding extracellular matrix is then altered. Because cellular metabolism depends to a large extent on cellular contacts and communications with connective tissue molecules, we have therefore investigated the interactions with extracellular matrix components of fibroblasts obtained from skin of patients affected with scleroderma. In comparison to fibroblasts from healthy skin, all fibroblasts from scleroderma patients had an increased adhesion capacity to collagens I, IV, VI, fibronectin, and laminin. In addition, whereas adhesion of control fibroblasts was stimulated by a pre-treatment with transforming growth factor-beta, adhesion patterns of scleroderma fibroblasts remained unchanged. However, pre-incubation of the cells with interferon-gamma decreased the adhesion of both scleroderma and control fibroblasts.

Cell Adhesion↗

PubMed1992

Altered regulation of collagen metabolism in scleroderma fibroblasts grown within three-dimensional collagen gels.

In systemic scleroderma (SSc) excessive deposition of collagen leads to fibrosis of various tissues including the skin. Previous studies have demonstrated that scleroderma fibroblasts in explant monolayer cultures are heterogeneous with respect to their levels of collagen synthesis. The critical role played by the extracellular matrix (ECM) in the modulation of fibroblast metabolism prompted us to study the regulation of collagen synthesis in scleroderma fibroblasts grown within three-dimensional collagen gels, a culture system representing more physiological conditions than monolayer cultures. Normal fibroblasts grown in this system dramatically reduce their collagen synthesis as compared to monolayer cultures. Quantification of total protein and collagen synthesis showed that scleroderma fibroblasts did not demonstrate the down regulation of collagen synthesis as observed in control fibroblasts, resulting in a much higher collagen synthesis in scleroderma fibroblasts compared to controls. However, also in this system scleroderma fibroblasts were heterogeneous in their response to the collagenous lattice. Ten strains were investigated, of which 3 were indistinguishable from controls, while 7 maintained higher levels of collagen production. In addition, our data showed that the changes in collagen synthesis on the protein level were accompanied by respective up- or downregulation on the mRNA level. These results indicate that an altered response to the surrounding ECM is an important factor in the disturbed regulation of connective tissue synthesis in scleroderma fibroblasts observed in vivo.

Adult↗

PubMed1991

Effect of histamine on collagen and collagen m-RNA production in human skin fibroblasts.

Direct effects of histamine on collagenous and non-collagenous protein synthesis by human skin fibroblasts were studied. Fibroblasts derived from human skin were incubated with various concentrations of histamine. Collagen and non-collagenous protein synthesis were measured by incorporation of 3H-proline. Both collagen synthesis measured as protein-bound hydroxyproline and non-collagenous protein synthesis measured as protein-bound proline increased in the presence of histamine at concentrations of 10(1)-10(2) micrograms/ml. Total RNA was extracted and m-RNA levels of various proteins were estimated by dot blot analysis, and densitometrically quantified. The levels of alpha 1(I) collagen and beta-actin m-RNA were clearly increased at the same concentrations. m-RNA levels of alpha 1(III) collagen were also increased but the rate was lower than that of alpha 1(I) collagen. No alteration of beta-tubulin m-RNA level was observed at the same concentrations. These results demonstrate that stimulation of collagen synthesis by histamine is pretranslationally controlled.

Actins↗

PubMed1991

Integrin alpha 2 beta 1 is upregulated in fibroblasts and highly aggressive melanoma cells in three-dimensional collagen lattices and mediates the reorganization of collagen I fibrils.

The ability of cultured human fibroblasts to reorganize and contract three dimensional collagen I gels is regarded as an in vitro model for the reorganization of connective tissue during wound healing. We investigated whether adhesion receptors of the integrin family are involved. It was found that synthesis and transcription of the alpha 2 beta 1 integrin (but not of alpha 1 beta 1 or alpha 3 beta 1) is selectively upregulated when fibroblasts are seeded into type I collagen gels. Time course experiments revealed that high synthetic levels of alpha 2 beta 1 parallel the gel contraction process and return to "baseline" levels after the contraction has subsided. Furthermore, function-blocking mAbs directed to the alpha 2 and beta 1 chain of integrins inhibited gel contraction. Remodelling of connective tissue can be important for tumor cells during invasion and formation of metastases. Therefore, we tested human melanoma cell lines for this function. Five out of nine melanoma lines contracted collagen gels in vitro. Among these, two highly aggressive melanoma cell lines (MV3 and BLM) most efficiently contracted gels almost reaching the rate of normal adult fibroblasts. In these cells, synthesis of alpha 2 beta 1 was also significantly upregulated when seeded into collagen I gels. Moreover, function blocking anti-alpha 2 in conjunction with anti-beta 1 chain mAbs completely inhibited gel contraction for several days. Other melanoma cells (530) with lower metastatic potential which were not able to contract gels, showed no induction of alpha 2 beta 1 synthesis in gel culture. Our results suggest an important role of integrin alpha 2 beta 1 in the contraction of collagen I by normal diploid fibroblasts during wound healing and in the reorganization of collagen matrices by highly aggressive human melanoma cells.

Adult↗

PubMed1991

Expression of intercellular adhesion molecule-1 (ICAM-1) in the skin of patients with systemic scleroderma.

The expression and tissue distribution of intercellular adhesion molecule-1 (ICAM-1) in skin biopsies from 12 patients with systemic (SSc) and localized (LS) scleroderma was studied and compared to the biopsies from patients with lupus erythematosus (LE) and normal individuals. In normal human skin ICAM-1 expression was restricted to the vascular endothelium, infiltrating mononuclear cells (MNC), and to few individual keratinocytes. In the inflammatory stage of SSc, however, the expression of ICAM-1 was dramatically increased at the site of MNC infiltrates and could also be detected on fibroblast-like cells lying well apart from these infiltrates in the deep dermis. In contrast, in LS ICAM-1 was expressed mainly at the sites of MNC infiltrates. In LE ICAM-1 expression was confined to the keratinocytes, endothelial cells, and mononuclear cells in the upper parts of the dermis. Analysis of serial tissue sections from patients with SSc demonstrated also colocalization of staining of ICAM-1 around blood vessels with LFA-1-positive lymphocytes. Increased expression of ICAM-1 in the dermis of patients with SSc may represent an important mechanism by which MNC become localized and retained at a site of connective tissue inflammation, leading to the activation of fibroblasts.

Adult↗

PubMed1990

Fibroblast-matrix interactions and their role in the pathogenesis of fibrosis.

The extracellular matrix has a complex structure which provides the scaffold of the connective tissue and influences many cellular functions. Fibroblast attachment, chemotaxis, and proliferation depend on the interaction of the cells with different components of the extracellular matrix. In addition, biosynthetic activities including protein and collagen synthesis are regulated by a two- or three-dimensional contact of fibroblasts with the surrounding matrix. Since scleroderma is characterized by an excessive deposition of collagen in the involved organs, many attempts have been made to define the altered cellular metabolism on a molecular level. This review summarized the role of fibroblast matrix interaction for the control of fibroblast functions during physiological processes and their activation in fibrosis.

Animals↗

PubMed1989

Collagenase gene expression in fibroblasts is regulated by a three-dimensional contact with collagen.

Collagenase activity in fibroblasts is regulated by cytokines and the interaction with the extracellular matrix. In this study we demonstrate that fibroblasts cultured within a three-dimensional collagen gel show a strong induction of collagenase gene expression. In addition to increased de novo synthesis most of the secreted enzyme was found to be activated leading to a high collagenolytic activity and complete degradation of collagen matrices after removal of fetal calf serum. Collagen I gene expression was found to be reduced under these conditions. These data suggest a specific modulation of cellular metabolism in response to contact with a three-dimensional collagenous matrix resulting in the divergent regulation of collagen and collagenase.

Adult↗

PubMed1989

Regulation of collagen VI expression in fibroblasts. Effects of cell density, cell-matrix interactions, and chemical transformation.

Collagen VI expression was studied in cultured human skin fibroblasts and mouse 3T3 cells using cDNA probes specific for alpha 1(VI), alpha 2(VI), and alpha 3(VI) chains. A 2-3-fold increase of these mRNAs was observed when fibroblasts were grown at increasing densities while only minimal changes occurred for the mRNA levels of collagens I and III, fibronectin, and beta-actin. Changes in mRNA correlated well with an increased production of corresponding proteins as determined by immunological assays. A comparable increase of alpha 1(VI) and alpha 2(VI) but not of alpha 3(VI) chain mRNAs was found for fibroblasts grown in a three-dimensional collagen gel after gel contraction. These conditions resulted, however, in a decrease of steady-state levels of collagens I and III and actin mRNAs. Transformation of 3T3 cells by phorbol ester did not change collagen VI mRNAs but caused a 3-5-fold reduction in mRNA levels for the other extracellular matrix proteins. These data strongly imply different regulatory mechanisms for the expression of collagen VI compared with collagens I and III and fibronectin. The differences may be correlated to changes in cell shape and reflect the requirement for collagen VI as a cell-binding protein.

Actins↗

PubMed1989

In situ hybridization--a useful tool for studies on collagen gene expression in cell culture as well as in normal and altered tissue.

We report the application of antisense RNA probes for in situ hybridization to identify collagen type I and type III mRNA synthesizing fibroblasts under in vitro and in vivo conditions in normal and wounded human skin. Non-specific hybridization was excluded by specific distribution patterns of alpha 1(I)- and alpha 1(III) probes in mouse fetuses. In addition, the specificity of hybridization was checked by sense probes, radioactively labelled transcripts of Gemini vectors and a keratin probe. In normal skin weakly activated fibroblasts were sparsely scattered within the dermis, while in wound healing processes mRNA both for alpha 1(I) and for alpha 1(III) was dramatically increased, thus suggesting that collagen synthesis is at least partly regulated at a pretranslational level. In addition, the intensity of the labelling, as defined by image analysis and the distribution pattern of collagen mRNA synthesizing cells, provide strong evidence that wound healing by primary intention starts within the deep dermis.

Adult↗

PubMed1989

Synergistic effect of tumor necrosis factor-alpha and interferon-gamma on collagen synthesis of human skin fibroblasts in vitro.

The effect of tumor necrosis factor-alpha (TNF alpha) and interferon-gamma (IFN gamma) on collagen metabolism by human diploid fibroblasts in confluent monolayer culture was examined. Recombinant TNF alpha reduced collagen mRNA levels 2-fold and stimulated collagenase mRNA levels 5-fold, while recombinant IFN gamma affected only collagen mRNA levels. The combination of TNF alpha (10 ng/ml) and IFN gamma (100 ng/ml) resulted in a much stronger (about 30-fold) reduction of collagen mRNA levels indicating that the two cytokines act synergistically. In contrast no such synergism was observed with respect to collagenase mRNA levels. The effect of TNF alpha and IFN gamma on collagen metabolism reported here indicates a complex interaction of different cytokines in the control of tissue remodeling that occurs during inflammation, repair, or atrophy.

Adult↗

PubMed1988

Influence of corticosteroids on chemotactic response and collagen metabolism of human skin fibroblasts.

Following chronic administration of corticosteroids in vivo, a number of complications occur, which mainly involve the metabolism of connective tissue cells. Therefore, several attempts have been made to develop corticosteroids, which show less pronounced side effects. Fibroblasts were kept in monolayer cultures and were exposed to corticosteroids demonstrating similar anti-inflammatory activity (prednicarbate, desoximetasone). Chemotaxis of fibroblasts was studied over 4 hr, protein and collagen synthesis were estimated using proteinchemical methods and also by dot blot hybridization. Corticosteroids used in a high dosage (10 microM) affected all biosynthetic capacities of the investigated fibroblasts. Protein synthesis and production of collagen types I and III were reduced and a similar decrease of mRNA levels for collagen type I could be found indicating an influence on the pretranslational control. In the same concentrations desoximetasone was much more active than prednicarbate. Fibroblast migration was dosage dependently inhibited from 10(-9) M to 10(-5) M for desoximetasone, while incubation with prednicarbate did not cause a reduction of the chemotactic response at concentrations lower than 10(-7) M. These data suggest that modifications of corticosteroids might result in a dissociation of some of their biological activities and can specifically influence their effects on biosynthetic capacities of fibroblasts.

Adrenal Cortex Hormones↗

PubMed1988

Collagen-type synthesis in human-hair papilla cells in culture.

Hair-papilla derived cells were grown in monolayer culture and revealed the typical morphology and growth pattern which was similar but not identical to control fibroblasts. Hair-papilla cells were found to produce considerable amounts of collagen type I and type III and fibronectin. Type IV collagen production could not be detected. The ratio of collagen type III and type I clearly differed from the pattern observed in normal fibroblasts, being much higher in hair-papilla cells, where type III accounted for more than 20% of total collagen synthesis. These data show that hair-papilla derived cells have biosynthetic capacities similar to those of human skin fibroblasts as well as characteristic differences, indicating that they represent a specialized fibroblast subpopulation.

Adult↗

PubMed1988

Regulation of collagen synthesis in fibroblasts within a three-dimensional collagen gel.

Fibroblasts cultivated within a three-dimensional collagen gel display an elongated, spindle-like morphology, reduce their proliferation rate, contact the gel to a very dense tissue, and modify their metabolic activity as compared to monolayer cultures. Collagen synthesis measured as protein-bound hydroxyproline is reduced to 5% of the values found in monolayer culture. The reduction involving type I and type III collagen is due to decreased de novo synthesis and not to enhanced degradation. Dot blot hybridization, Northern blot analysis, and in situ hybridization using collagen I- and III-specific cDNA probes demonstrate that reduced biosynthesis rates are reflected by a marked reduction of pro alpha 1 (I), pro alpha 2 (I), and pro alpha 1 (III) collagen mRNA indicating pretranslational regulation. A similar reduction was observed for actin mRNA whereas levels of tubulin mRNA were similar for fibroblasts in monolayer culture or cultivated within the three-dimensional collagen gels. The data suggest a specific reprogramming of various cellular activities in response to contact with the reconstituted extracellular matrix.

Blotting, Northern↗

PubMed1988

Evidence for LTB4/12-HETE binding sites in a human epidermal cell line.

We identified leukotriene B4 (LTB4)/12-hydroxyeicosatetraenoic acid (12-HETE) binding sites in a squamous cell cancer-derived human epidermal cell line. Analysis of the binding data revealed a single class of binding sites with a dissociation constant of 0.16 microM and a Bmax of 3.8 x 10(6) sites per cell. Competitive binding assays with various eicosanoids at 37 degrees C showed nearly equal binding of 12(S)-HETE, 12(R)-HETE and LTB4. 5(S)-HETE and LTB4-analogs bound with lesser affinity. Specific LTB4 binding at 37 degrees C could also be demonstrated in freshly isolated normal human keratinocytes. Since lipoxygenase-derived eicosanoids are thought to play an important role in hyperproliferative and inflammatory skin diseases, the identification of LTB4/12-HETE binding sites in keratinocytes could have implications for the development of new drugs controlling these disease processes.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗

PubMed1988

A defective cell surface collagen-binding protein in dermatosparactic sheep fibroblasts.

Fibroblasts from dermatosparactic sheep fail to contract collagen gels and show a reduced attachment to collagenous substrates. By comparing collagen-binding membrane proteins of normal (+/+), homozygote (-/-), and heterozygote (+/-) fibroblasts, we present evidence that the interaction of normal fibroblasts with native type I collagen involves a protein of apparent Mr = 34,000 which is absent from dermatosparactic fibroblasts and seems to be related to anchorin CII. This conclusion was reached from the following experiments: (a) On a blot of membrane proteins from normal fibroblasts radioactively labeled type I collagen bound predominantly to a protein band of 34 kD; dermatosparactic membranes revealed only a small amount of binding to a component with a molecular mass of 47 kD. (b) After separation of normal fibroblast membrane proteins on type I collagen-Sepharose, a collagen-binding component of 34 kD was found which was absent from the corresponding fraction of dermatosparactic membranes. (c) Antibodies to anchorin CII stained the surface of normal (+/+), but not of dermatosparactic (-/-) fibroblasts and labeled a 34-kD component after immunoblotting of normal fibroblast membrane proteins. (d) After metabolic labeling of fibroblasts with [35S]methionine and immunoprecipitation with anti-anchorin CII, 40- and 34-kD components were precipitated from extracts of normal fibroblasts, while the latter component was absent from affected cells. Similar differences were found after immunoblotting of membranes from whole normal or affected skin. These data indicate that dermatosparaxis of sheep involves a molecular defect of a collagen-binding protein. Therefore this disease represents a model to study the complex interaction of cells with the extracellular matrix on a molecular level.

Animals↗

PubMed1988

[Pathophysiology of fibroses. Progressive systemic scleroderma as a model disease].

Fibrosis is characterized by excessive deposition of connective tissue in the involved organs. Although the prime event in the pathogenesis is still poorly understood, several mechanisms are discussed, which finally result in the activation of fibroblasts. Recent studies have demonstrated that immunocompetent cells play a crucial role during the initial phases of the development of fibrosis. Therefore, several mediators have been characterized, which are secreted by platelets, lymphocytes and macrophages and which can attract fibroblasts, induce proliferation and collagen synthesis in mesenchymal cells. These include PDGF, EGF, TGF--beta and many others. In addition, gamma-interferon has been shown to inhibit chemotaxis of fibroblasts and to reduce collagen mRNA levels. A controlled interaction of all the different mediators is required to guarantee a normal functioning of connective tissue. Alterations in these regulation steps can result in excessive deposition of connective tissue and the development of fibrotic processes.

Collagen↗

PubMed1986

Defective attachment of dermatosparactic fibroblasts to collagens I and IV.

Attachment of fibroblasts from dermatosparactic sheep and cattle to collagenous substrates (types I and IV) is defective (30-50%) when compared with fibroblasts from normal or heterozygous animals. The difference was independent of the amount of substrate, incubation time and protein synthesis. No differences were observed in the binding to fibronectin or laminin. Reduced attachment to collagen can be partially restored by adding fibronectin. The polygonal morphology of dermatosparactic cells was, however, not altered by attachment and growth on dishes coated with different collagens or fibronectin. Reduced interaction with collagens could be due to changes in specific receptors and may represent a further pathological change in dermatosparactic animals.

Animals↗

PubMed1986

Modulation of collagen type synthesis in organ and cell cultures of fibroblasts.

Fibroblast cultures are widely used to study abnormalities of collagen metabolism in both inborn and acquired diseases. However, there is reason to question the extent to which the experimental information obtained from in vitro culture systems in fact reflects the in vivo situation. In the present study we analyzed the proportions of collagens I and III synthesized by human and mouse skin fibroblasts maintained under various culture conditions. The amount of type III collagen extracted from skin specimens was lower than that which was newly synthesized in organ culture. Cells obtained by enzymatic disintegration of skin specimens synthesized more type III collagen than fibroblasts grown from explants. However, subcultivation of the enzymatically liberated cells resulted in a continuous decline of type III collagen production which eventually reached levels similar to those observed in explant cultures.

Animals↗