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Biomedical subjects

G Gabbiani

Publications and source records attributed to G Gabbiani.

At least 109 records · Page 6Linked to original sources
PubMed1994

Morphological and immunochemical differences between keloid and hypertrophic scar.

There are two types of excessive scarring, keloid and hypertrophic scar. Contrary to hypertrophic scars, keloids do not regress with time, are difficult to revise surgically, and do not provoke scar contractures. These two lesions require different therapeutic approaches but are often confused because of an apparent lack of morphological differences. We have investigated the collagen organization and the possible presence of alpha-smooth muscle (SM) actin-expressing myofibroblasts in these conditions. Keloids contain large, thick collagen fibers composed of numerous fibrils closely packed together. In contrast hypertrophic scars exhibit modular structures in which fibroblastic cells, small vessels, and fine, randomly organized collagen fibers are present. We confirm that such nodular structures are always present in hypertrophic scar and rarely in keloid. Furthermore, only nodules of hypertrophic scars contain alpha-SM actin-expressing myofibroblasts. Electron microscopic examination supports the above-mentioned differences in collagen organization and in fibroblastic features and shows the presence of an amorphous extracellular material surrounding fibroblastic cells in keloid. The presence in hypertrophic scar myofibroblasts of alpha-SM actin, the actin isoform typical of vascular SM cells, may represent an important element in the pathogenesis of contraction. Interestingly, when placed in culture fibroblasts from hypertrophic scars and keloid express similar amounts of alpha-SM actin, suggesting that local microenvironmental factors influence in vivo the expression of this protein. Thus several morphological and immunohistochemical differences exist between hypertrophic scar and keloid that are useful for the biological and pathological characterization of the two lesions.

Actins↗
PubMed1994

Heterogeneity of rat aortic smooth muscle cell replication during development: correlation with replicative activity after experimental endothelial denudation in adults.

Proliferation of smooth muscle cells (SMCs) is a major event in vascular development and atheromatous plaque formation. In order to characterize SMC replicative potential, newborn rats have been injected with 3H-thymidine (3H-TdR) during their first week of life when most of SMCs were proliferating; then, 3H-TdR labelling was evaluated in adult rats. Depending on the number of mitosis that SMCs had accomplished after the first week of life, four different SMC subpopulations could be defined indicating that rat aortic SMCs are heterogeneous in their replicative activity. 5-Bromo-2'-deoxyuridine (BrdU) incorporation after balloon induced endothelial denudation of rat aorta in adult rats showed that SMCs entering into the cell cycle were mainly devoid of 3H-TdR labelling. This category could derive from two distinct SMC subpopulations: SMCs which were arrested in their proliferation before or just after birth or SMCs which had actively replicated during development. Thus, one (or two) subpopulation(s) of rat aortic SMCs, characterized by a particular replicative activity during development, is (are) selectively activated after balloon induced endothelial denudation.

Animals↗
PubMed1994

All histological types of primary human rhabdomyosarcoma express alpha-cardiac and not alpha-skeletal actin messenger RNA.

Eleven human primary rhabdomyosarcomas (RMSs), including all histological variants, were analyzed morphologically, immunohistochemically for intermediate filament proteins and actin isoforms, and by means of Northern blots with probes specific for total actin, alpha-skeletal (SK), alpha-cardiac (CARD), and alpha-smooth muscle actin messenger (m)RNAs. All tumors disclosed ultrastructural evidence of skeletal muscle features with terminal differentiation in three cases. The RMSs contained immunohistochemically the intermediate filament proteins vimentin and desmin and reacted positively with the alpha-sarcomeric actin antibody, which recognizes alpha-SK and alpha-CARD actin isoforms. All RMSs reacted with the total actin probe, recognizing at 2.1 kb cytoplasmic actin mRNAs and at 1.7 kb alpha-actin mRNAs. With the specific probes, all RMSs expressed alpha-CARD actin mRNA, four neoplasms expressed also alpha-smooth muscle actin mRNA, whereas the probe for alpha-SK actin mRNA never produced a signal except in one case, in which the tumor masses were intermingled with non-neoplastic preexistent striated muscle fibers. Because alpha-CARD and alpha-smooth muscle actins are transiently expressed during normal skeletal muscle development, RMSs seem to follow normal skeletal myogenesis without completing the final step, consisting of alpha-SK actin mRNA expression. The use of Northern blots for alpha-CARD actin as an adjunct to conventional techniques may be helpful for the precise identification of primary RMSs compared to other soft tissue neoplasms.

Actins↗
PubMed1993

Modulation of perisinusoidal cell cytoskeletal features during experimental hepatic fibrosis.

Hepatic perisinusoidal cells (PSCs) proliferate and are thought to be the principal source of extracellular matrix proteins during the development of liver fibrosis. We have studied the classical model of carbon tetrachloride induced liver fibrosis in order to evaluate the possible modulation of PSCs into a synthetically active and contractile cell: the myofibroblast (MF). At the ultrastructural level, this modulation was characterized by reduction of lipid vacuoles and appearance of a developed rough endoplasmic reticulum as well as of microfilament bundles. On investigating the cytoskeletal equipment of PSCs and MFs using light and electron microscopic immunohistochemistry, we found a heterogeneity of phenotypic features. While typical PSCs in normal and fibrotic livers always contained desmin, MFs expressed alpha-smooth muscle (SM) actin in areas of tissue injury and active fibrogenesis. Cells co-expressing alpha-SM actin and desmin were most prominent in the prevenular zone of the lobule (known to be vulnerable to carbon tetrachloride toxicity) and in developing fibrous septa. As demonstrated by immunogold electron microscopy, labelling of microfilament bundles by alpha-SM actin antibody was noted in PSCs containing lipid droplets in early stages of fibrosis; here MFs gradually accumulated and showed alpha-SM actin containing microfilament bundles. In scar tissue, alpha-SM actin expression decreased in both PSCs and myofibroblasts. Our observations support the concept of phenotypic plasticity of PSCs and confirm, at the ultrastructural level, previous suggestions of modulation of these cells into MFs in the course of liver fibrosis.

Actin Cytoskeleton↗
PubMed1993

Alpha-smooth muscle actin and other stromal markers in endometrial mucosa.

Stromal-epithelial interactions as expressed by alpha-smooth muscle actin (alpha-SM actin) collagen type IV, fibronectin, laminin and tenascin were studied in normal and pathological endometrial mucosa. There was complete or incomplete cuffing of scattered endometrial glands by alpha-SM actin mostly in the basal layer of endometrial mucosa and in dilated or cystic glands. Individual adenocarcinomatous glands were not encircled by alpha-SM actin-positive cells. Collagen type IV and laminin were found surrounding all glands irrespective of the presence of periglandular alpha-SM actin. Fibronectin was diffusely present in the stroma. Tenascin was identified, albeit not exclusively, in a periglandular location similar to that of alpha-SM actin. We conclude that the periglandular cells staining for alpha-SM actin, which were negative for cytokeratins, are probably myofibroblasts (MFs). Since this phenomenon was most commonly observed in dilated and cystic glands, we suggest that stromal cells immediately surrounding these glands may be subjected to mechanical or other stress resulting, as in other situations of tissue remodelling, in the development of MFs. This may also explain the appearance of tenascin in the same location. Thus, our finding may represent a further example of the local modulation of stromal cell phenotype, possibly under the action of micro-environmental factors.

Actins↗
PubMed1993

GM-CSF-induced granulation tissue formation: relationships between macrophage and myofibroblast accumulation.

We have studied the formation of granulation tissue around osmotic minipumps delivering granulocyte macrophage-colony stimulating factor (GM-CSF) chronologically in the rat using electron microscopy and immunohistochemistry at the light and electron microscopic levels, with specific antibodies against alpha-smooth muscle (SM) actin and rat macrophages. At 2 and 3 days after pump implantation, GM-CSF application produced an extensive inflammatory reaction characterized by edema and the accumulation of polymorphonuclear cells and macrophages. Gradually, polymorphonuclear cells decreased in number and macrophages became arranged in large clusters. The expression of alpha-SM actin in fibroblastic cells of the granulation tissue started from the 4th day after pump implantation and progressed up to the 7th day. Double immunofluorescence staining showed macrophage clusters in relation to alpha-SM actin-rich fibroblastic cells. Electron microscopic examination confirmed that the fibroblasts containing alpha-SM actin-positive stress fibers were found initially in close proximity to clustered macrophages. The delivery of platelet-derived growth factor (PDGF) and tumor necrosis factor-alpha (TNF-alpha) by the osmotic minipump induced an accumulation of macrophages, but in a much smaller number compared with those seen after GM-CSF application; these macrophages were never assembled in clusters and, furthermore, TNF-alpha and PDGF did not stimulate alpha-SM actin expression in fibroblastic cells. Our results suggest that after GM-CSF administration, the cluster-like accumulation of macrophages plays an important role in stimulating alpha-SM actin expression in myofibroblasts. Our results may be relevant to the understanding of the processes leading to granulation tissue formation in this and other experimental models.

Actins↗
PubMed1993

Relationship between mevalonate pathway and arterial myocyte proliferation: in vitro studies with inhibitors of HMG-CoA reductase.

The role of mevalonate and its products (isoprenoids) in the control of cellular proliferation was examined by investigating the effect of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (vastatins) on growth and on cholesterol biosynthesis of cultured arterial myocytes (SMC). Simvastatin (S) and fluvastatin (F), but not pravastatin (P), decreased the rate of growth of rat vascular SMC. The inhibition, evaluated as cell number, was dose-dependent with IC50 values of 2.8 and 2.2 microM for S and F, respectively; P (1-500 microM) was inactive. The inhibition of cell growth induced by 3.5 microM S (70% decrease) was prevented completely by the addition of 100 microM mevalonate, partially (70-85%) by the addition of 10 microM geraniol, 10 microM farnesol and 5 microM geranylgeraniol, but not by the addition of squalene, confirming the specific role of isoprenoid metabolites in regulating cell proliferation. All the tested vastatins inhibited the incorporation of [14C]acetate into cholesterol but P had 800 times lower potency than S and F. Similar results were obtained in SMC from human femoral artery. At least 80% inhibition of cholesterol synthesis was necessary to induce a decrease in SMC proliferation. To further investigate the relationship between cholesterol synthesis and cell growth, two enantiomers of F were investigated. The enantiomer more active on HMG-CoA reductase was 70- and 1.6-fold more potent on arterial myocyte proliferation than its antipode and the racemic mixture, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Acyclic Monoterpenes↗
PubMed1993

Transforming growth factor-beta 1 induces alpha-smooth muscle actin expression in granulation tissue myofibroblasts and in quiescent and growing cultured fibroblasts.

Granulation tissue fibroblasts (myofibroblasts) develop several ultrastructural and biochemical features of smooth muscle (SM) cells, including the presence of microfilament bundles and the expression of alpha-SM actin, the actin isoform typical of vascular SM cells. Myofibroblasts have been proposed to play a role in wound contraction and in retractile phenomena observed during fibrotic diseases. We show here that the subcutaneous administration of transforming growth factor-beta 1 (TGF beta 1) to rats results in the formation of a granulation tissue in which alpha-SM actin expressing myofibroblasts are particularly abundant. Other cytokines and growth factors, such as platelet-derived growth factor and tumor necrosis factor-alpha, despite their profibrotic activity, do not induce alpha-SM actin in myofibroblasts. In situ hybridization with an alpha-SM actin probe shows a high level of alpha-SM actin mRNA expression in myofibroblasts of TGF beta 1-induced granulation tissue. Moreover, TGF beta 1 induces alpha-SM actin protein and mRNA expression in growing and quiescent cultured fibroblasts and preincubation of culture medium containing whole blood serum with neutralizing antibodies to TGF beta 1 results in a decrease of alpha-SM actin expression by fibroblasts in replicative and non-replicative conditions. These results suggest that TGF beta 1 plays an important role in myofibroblast differentiation during wound healing and fibrocontractive diseases by regulating the expression of alpha-SM actin in these cells.

Actins↗
PubMed1993

A quantitative study of the differential expression of alpha-smooth muscle actin in cell populations of follicular and non-follicular origin.

Alpha-smooth muscle actin (ASMA) is an actin isoform present in the filaments of smooth muscle cells, myofibroblasts, and a specific region of hair follicle dermal sheath in vivo. We employed double immunofluorescence, two-dimensional electrophoresis, Western blots and DNA, protein, and actin isoform determinations to quantify the relative levels of ASMA in four populations of cultured hair follicle dermal cells, and fibroblasts derived from three regions of adult and comparable areas of 4-d rat skin. Although follicle sheath populations were morphologically similar, they contained variable proportions of cells that expressed ASMA. Tissue from the most positive region in situ, the lower/mid sheath, also gave rise to the most positive cells in culture (98%), followed by the end bulb (85%) and then upper sheath (50%). The follicle dermal cells (including papilla 81%) displayed and maintained levels of expression well above those obtained for adult (below 10%) or 4-d (9-40%) fibroblasts, and even cultured smooth muscle cells. It was also confirmed that levels of expression in adult fibroblasts could be positively correlated with hair follicle density in the biopsies from which they were initiated. Differential expression of ASMA in follicle subpopulations provides an insight into how their behavior may be linked to their specialized functions, for example, their likely involvement in the mechanics of the hair cycle. Moreover, the proposition that hair follicle dermal cells represent unappreciated constituents of general skin fibroblast cultures has substantial implications.

Actins↗
PubMed1993

Parathyroid hormone-related protein increases cAMP production in mammary epithelial cells.

Parathyroid hormone-related protein (PTHrP) is a major cause of malignant hypercalcemia but has been found in many nontumoral tissues as well. Thus it is produced by the mammary gland during lactation and released into milk. Whether PTHrP directly affects breast tissue is however not known. We investigated the effects of PTHrP on adenosine 3',5'-cyclic monophosphate (cAMP) production in primary cultures of mammary epithelial cells isolated from lactating rats. On the 7th day in culture, synthetic PTHrP-(1-34), recombinant (r) PTHrP-(1-108), and rPTHrP-(1-141) stimulated cAMP production in a concentration-dependent manner. Thus PTHrP-(1-34) induced a 1.92 +/- 0.04-fold stimulation of cAMP production (mean +/- SE, n = 5 separate experiments, P < 0.001). At the time of maximal responsiveness to PTHrP, a significant proportion of the cells was characterized by an elongated shape and a positive immunofluorescent staining for both prekeratin and alpha-smooth muscle actin 1, compatible with a myoepithelial phenotype. It therefore appears that PTHrP can stimulate the production of cAMP in mammary cells, suggesting a possible autocrine/paracrine regulatory function for PTHrP in breast tissue.

Animals↗
PubMed1993

Age influences the replicative activity and the differentiation features of cultured rat aortic smooth muscle cell populations and clones.

The replicative activity and the differentiation features of aortic smooth muscle cells (SMCs) cultured as whole populations or clones from newborn (4-day-old), young adult (6-week-old), and old (18-month-old) rats were studied by means of cell counting, [3H]thymidine incorporation, and measurement of the expression of cytoskeletal proteins and mRNAs. In whole populations at the fifth passage, replicative activity increased and differentiation features (ie, expression of alpha-smooth muscle actin, desmin, and smooth muscle myosin heavy chains) decreased with increasing age of the donor animal. SMC clones derived from newborn or young adult rats showed more differentiated cytoskeletal features than their parental populations; however, most SMC clones from old rats showed dedifferentiated features similar to those observed in their parental populations. Our results suggest that (1) SMCs of the rat aortic media behave as a heterogeneous population; (2) cultured whole SMC populations behave differently from clones as far as their replicative activity and differentiation features are concerned; and (3) SMCs derived from old rats, whether grown as whole populations or as clones, dedifferentiate more substantially and replicate more actively than corresponding cultures from newborn or young adult rats when submitted to the same amount of serum growth factors; these differences may play a role in arterial development as well as in the formation and evolution of the atheromatous plaque.

Actins↗
PubMed1993

Age-related changes in sarcoplasmic reticulum Ca(2+)-ATPase and alpha-smooth muscle actin gene expression in aortas of normotensive and spontaneously hypertensive rats.

The expression of the sarcoplasmic reticulum (SR) Ca(2+)-ATPase gene and the SR Ca2+ pump function were investigated in thoracic aortas of 5- and 17-week-old normotensive Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHRs). The relative level of the two isoforms of SR Ca(2+)-ATPase mRNA expressed in the aorta (i.e., SERCA 2a and SERCA 2b) was determined by quantitative S1 nuclease protection analysis and normalized to the level of alpha-smooth muscle (alpha-Sm) actin mRNA. The level of alpha-Sm actin mRNA itself was normalized to the level of 18S ribosomal RNA using slot-blot hybridization assays. Total SR Ca2+ pump activity was estimated by measuring the rate of oxalate-supported Ca2+ uptake in homogenates. At 5 weeks, the amount of SERCA 2a and SERCA 2b mRNA, normalized to 18S ribosomal RNA, and the ratio of alpha-Sm actin mRNA to 18S RNA were identical in SHR and WKY rats. The Ca2+ pump activity was similar in the two strains of rats at 5 weeks. From 5 to 17 weeks, the amount of SERCA 2a mRNA increased in both strains while the level of SERCA 2b mRNA remained constant. The Ca2+ pump activity was unchanged in SHRs and tended to decrease in WKY rats. Accordingly, the change in the ratio of the SR Ca(2+)-ATPase mRNA isoforms does not appear to influence SR function. The level of alpha-Sm actin mRNA and SERCA 2a mRNA increased in parallel from 5 to 17 weeks in both strains.(ABSTRACT TRUNCATED AT 250 WORDS)

Actins↗
PubMed1993

Rat alveolar myofibroblasts acquire alpha-smooth muscle actin expression during bleomycin-induced pulmonary fibrosis.

The majority of fibroblasts in alveolar septa are characterized by the presence of cytoplasmic bundles of microfilaments that contain cytoplasmic actin isoforms; these cells have been named contractile interstitial cells or V-type myofibroblasts. In the rat, they express desmin as intermediate filament protein. In this study, we explored the possibility that modulation and replication of such septal fibroblasts result in the appearance of alpha-smooth muscle (alpha-SM) actin-positive myofibroblasts, typical of lung fibrosis. Experimental pulmonary fibrosis was produced by a unique intratracheal instillation of bleomycin to 28 rats. Eight additional rats used as controls received the equivalent volume of saline. Paraffin and frozen sections of lungs were examined at days 1, 3, 5 and 7 after treatment. Microfilaments and intermediate filaments were stained using antibodies against total actin, alpha-SM actin, desmin, vimentin, keratin, and SM myosin. Electron microscopic labeling of desmin and alpha-SM actin using immunogold technique was done on Lowicryl K4M resin-embedded specimens. alpha-SM actin appeared in desmin-positive alveolar fibroblasts as early as 24 hours after intratracheal bleomycin instillation; the modulation of alpha-SM actin in these cells was preceded by a lymphomonocytic infiltration of alveolar septa. Twenty-four hours to 3 days after bleomycin administration, a proliferation of alveolar myofibroblasts occurred. Fibrosis with laying down of collagen fibers took place after the above mentioned cellular modifications. Our results support the view that septal fibroblastic cells can modulate into typical alpha-SM actin-containing myofibroblasts during experimental bleomycin-induced pulmonary fibrosis. In such a modulation a possible role of cytokines, particularly of transforming growth factor-beta, is considered.

Actin Cytoskeleton↗
PubMed1992

O-acylated heparin derivatives with low anticoagulant activity decrease proliferation and increase alpha-smooth muscle actin expression in cultured arterial smooth muscle cells.

Selectively O-acylated derivatives of various glycosaminoglycans were prepared and tested in vitro for their anticoagulant activity and their antiproliferative effect on rat and rabbit smooth muscle cells. When O-acylation (butyrylation or hexanoylation) had been performed on periodate-depolymerized heparin fragments having very low anticoagulant activity, the antiproliferative potency was markedly increased (IC50 = 2 and 1 micrograms/ml respectively, versus 31 micrograms/ml for starting compound) without an increase in anticoagulant activity. The antiproliferative activity was related to the degree of acylation. The O-acylated derivatives of heparin fragments were also very active in reversing the de-differentiation of smooth muscle cell in culture, as estimated by the increase in the expression of alpha-smooth muscle actin and alpha-smooth muscle actin mRNA.

Actins↗
PubMed1992

Inhibition of rat hepatic lipocyte activation in culture by interferon-gamma.

Hepatic lipocytes (perisinusoidal, Ito cells) are the primary matrix-producing cells in liver fibrosis. During liver injury they undergo activation, a process characterized by cell proliferation and increased fibrogenesis. We and others have established a culture model in which in vivo features of lipocyte activation can be mimicked by cells grown on plastic. Additionally, we recently showed that activation is associated with new expression of smooth muscle-specific alpha-actin both in vivo and in culture. Although interferon-gamma is known to inhibit collagen production in some systems, its action as a general modulator of lipocyte activation has not been examined; this issue forms the basis for our study. In culture-activated lipocytes, interferon-gamma (1,000 U/ml) significantly inhibited lipocyte proliferation as assessed by [3H]thymidine incorporation assay and nuclear autoradiography. In time-course studies of activation, it also markedly reduced expression of smooth muscle-specific alpha-actin and its messenger RNA. In dose-response experiments, maximal inhibitory effects on smooth muscle-specific alpha-actin mRNA gene expression were achieved with as little as 10 U interferon-gamma/ml. Inhibition of cellular activation was reversible; after interferon-gamma withdrawal, messenger RNA levels of smooth muscle-specific alpha-actin returned to untreated control levels. The effect of interferon-gamma extended to extracellular matrix gene expression, with reduction of type I collagen, type IV collagen and total fibronectin messenger RNAs to 3%, 24% and 15% of untreated control levels, respectively. In contrast to the marked effects on smooth muscle-specific alpha-actin and extracellular matrix gene expression, interferon-gamma reduced total protein synthesis by only 17.7%.(ABSTRACT TRUNCATED AT 250 WORDS)

Actins↗
PubMed1992

Two cloned cerebral endothelial cell phenotypes: an in vitro model for angiogenesis?

Expression of smooth muscle alpha-actin and migratory behaviour of cloned cerebral endothelial cells (cEC) which exhibited two distinct phenotypes (type I, type II) were studied. Removal of mitogenic factors (alpha ECGF, ECGS) and heparin from the culture medium resulted in a smooth muscle-like appearance (type II) of the cells, expression of smooth muscle alpha-actin protein and smooth muscle actin mRNA and in an increased migratory activity. In contrast, addition of growth factors and heparin led to a cobblestone-like phenotype (type I) which lacked the expression of smooth muscle alpha-actin but expressed other proteins as determined by 2-D-gel electrophoresis.

Actins↗
PubMed1992

Alpha-smooth muscle actin is expressed in a subpopulation of cultured and cloned fibroblasts and is modulated by gamma-interferon.

Clinical and experimental investigations have shown that, during wound healing and fibrocontractive diseases, fibroblasts acquire, more or less permanently according to the situation, morphological and biochemical features of smooth muscle (SM) cells including the expression of alpha-SM actin. Primary and passaged cultures of rat and human fibroblasts contain a subpopulation of cells expressing alpha-SM actin. These cells could derive from SM cells and/or pericytes present in the tissue from which cultures have been produced or represent bona fide fibroblasts. We have investigated the presence of alpha-SM actin in fibroblast cultures, clones, and subclones. In all cases the fibroblastic populations studied showed a proportion of alpha-SM actin expressing cells. Even after cloning, we never obtained populations negative for alpha-SM actin. We conclude that alpha-SM actin expression in fibroblastic cultures is not due to contaminant cells but is a feature of fibroblasts themselves. Our results support the view that fibroblastic cells are a heterogeneous population. It has been previously shown that gamma-interferon (gamma-IFN) decreases alpha-SM actin expression in SM cells. In rat and human fibroblasts, gamma-IFN decreases alpha-SM actin protein and mRNA expression as well as proliferation. The properties of this cytokine make it a good candidate for exerting an anti-fibrotic activity in vivo.

Actins↗