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Query: UMLS:C0036421 (PSS)
 10,989 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Activation of both cellular and humoral immunity are early events in systemic sclerosis (SSc) that appear to contribute to disease pathogenesis. Recent reports suggest that CD4+ and CD8+ T cells and a subset of gamma delta T cells each may play a role in the disease. Interest in potential profibrotic effects of transforming growth factor-beta in SSc continues. Expression of a variety of adhesion molecules is increased on fibroblasts and endothelial cells in SSc patients, as are circulating levels of the same molecules. Different autoantibody specificities are generated in B cells from tight-skin mice by use of identical VH genes, with similar V kappa genes but different J kappa segments. Centromeric proteins, topoisomerase I, RNA polymerases I, II, and III, fibrillarin, and upstream binding factor may become autoantibody targets in SSc because they are presented to the immune system as part of larger multiunit complexes. Homology between target autoantigens and infectious agents suggests that molecular mimicry initiates some autoantibody responses in SSc patients. Genetic factors influence the pattern of autoantibodies produced in different populations. Exogenous agents can induce autoantibodies in humans and mice that are similar to those seen in spontaneous SSc.
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PMID:Immunologic aspects of scleroderma. 857 76

Connective tissue growth factor (CTGF) is a novel peptide that exhibits platelet-derived growth factor-like activities and is produced by skin fibroblasts after activation with transforming growth factor-beta. Coordinate expression of transforming growth factor-beta followed by CTGF during wound repair suggests a cascade process for control of tissue regeneration. We recently reported a significant correlation between CTGF mRNA expression and histologic sclerosis in systemic sclerosis. To confirm the relation between CTGF and skin fibrosis, we investigated CTGF gene expression in tissue expression in tissue sections from patients with localized scleroderma, keloid, other sclerotic skin disorders using nonradioactive in situ hybridization. In localized scleroderma, the fibroblasts with positive signals for CTGF mRNA were scattered throughout the sclerotic lesions with no preferential distribution around the inflammatory cells or perivascular regions, whereas the adjacent nonaffected dermis was negative for CTGF mRNA. In keloid tissue, the fibroblasts positive for CTGF mRNA were diffusely distributed, especially in the peripheral expanding lesions. In scar tissue, however, the fibroblasts in the fibrotic lesions showed partially positive signals for CTGF mRNA. In eosinophilic fasciitis, nodular fasciitis, and Dupuytren's contracture, CTGF mRNA was also expressed partially in the fibroblasts of the fibrotic lesions. Our findings reinforce a correlation between CTGF gene expression and skin sclerosis and support the hypothesis that transforming growth factor-beta plays an important role in the pathogenesis of fibrosis, as it is the only inducer for CTGF identified to date.
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PMID:Connective tissue growth factor gene expression in tissue sections from localized scleroderma, keloid, and other fibrotic skin disorders. 861 12

Fibrosis is a disorder characterized by a qualitative and quantitative alteration of the deposition of extracellular matrix with accumulation of mesenchymal cells in replacement of normal tissue. The sequence of events leading to fibrosis of an organ involves the subsequent processes of injury with inflammation and disruption of the normal tissue architecture, followed by tissue repair with accumulation of mesenchymal cells in this area. A similar sequence of events occurs in wound healing with formation of normal, limited and transient granulation tissue, while in fibrosis, a maladaptive repair leads to an extensive, exaggerated process with functional impairment. Inflammatory cells (mainly mononuclear phagocytes), platelets, endothelial cells, and type II pneumocytes play a direct and indirect role in tissue injury and repair. The evaluation of several human fibrotic lung diseases, five diffuse (idiopathic pulmonary fibrosis (IPF); adult respiratory distress syndrome (ARDS); coal workers' pneumoconiosis (CWP); Hermansky-Pudlak syndrome (HPS); systemic sclerosis (SS)) and two focal (tumour stroma in lung cancer; and obliterative bronchiolitis (OB) after lung transplantation), has shown that several cytokines participate in the local injury and inflammatory reaction (interleukin-1 (IL-1), interleukin-8 (IL-8), monocyte chemotactic protein-1 (MCP-1), and tumour necrosis factor-alpha (TNF-alpha)), while other cytokines are involved in tissue repair and fibrosis (platelet-derived growth factor (PDGF), insulin-like growth factor-1 (IGF-1), transforming growth factor-beta (TGF-beta), and basic-fibroblast growth factor (b-FGF)). A better understanding of the cytokines and cytokine networks involved in lung fibrosis leads to the possibility of new therapeutic approaches.
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PMID:The role of cytokines in human lung fibrosis. 868 Mar 82

Clinically distinct fibrosing processes affecting the skin, selected internal organs, or both in a characteristic pattern are a common cause of morbidity. In addition to systemic sclerosis, the prototype idiopathic fibrosing disorder, these conditions include the eosinophilia-myalgia syndrome, epidemic toxic oil syndrome, eosinophilic fasciitis, localized forms of scleroderma, keloid, and the newly described entity of fibrosing colonopathy. The pathogenesis of these disorders, although still incompletely understood, appears to share similarities with that of systemic sclerosis. Insights into these diseases have recently emerged from epidemiologic and toxicoepidemiologic investigations, in situ hybridization and polymerase chain reaction amplification of target genomes, and in vivo and in vitro experimental research. Minor contaminants in food supplements, activation and degranulation of eosinophils, altered expression of CD34 antigen on dendritic cells, disordered regulation of fibroblast apoptosis and proliferation, infection with Borrelia organisms, and cytokines such as transforming growth factor-beta, interleukin-4, and connective tissue growth factor are implicated in inducing an accentuated and persistent fibrogenic host response to injury, resulting in tissue fibrosis. In addition, humoral and cellular autoimmunity may also be implicated.
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PMID:Eosinophilia-myalgia syndrome, eosinophilic fasciitis, and related fibrosing disorders. 937 86

Scleroderma fibroblasts exhibit numerous phenotypic differences when compared with healthy skin fibroblasts. Some of these differences, in particular overexpression of collagen type I and other extracellular matrix proteins, parallel the effect of transforming growth factor-beta (TGF-beta) on dermal fibroblasts, suggesting that the scleroderma fibroblast phenotype may result from activation of autocrine TGF-beta signaling. To test this hypothesis we examined the role of TGF-beta Type I and Type II receptors in regulating collagen type I transcription. We have shown that overexpression of either Type I or Type II receptors significantly (3-4-fold) increases alpha2 (I) collagen promoter activity in transient transfection assays in dermal fibroblasts. Addition of anti-TGF-beta antibody abolished, whereas addition of plasmin enhanced, the stimulatory effect of receptor overexpression on collagen promoter activity, suggesting that this effect depends on autocrine TGF-beta. Moreover, these cotransfection experiments indicated that expression levels of TGF-beta receptors is a limiting factor in the autocrine regulation of collagen type I transcription by TGF-beta. Comparison of the TGF-beta receptor Type I and Type II mRA expression levels in scleroderma and normal fibroblasts have indicated elevated expression (2-fold) of both receptor types in scleroderma cells, which correlated with increased binding of TGF-beta. Significantly, elevated TGF-beta receptor levels correlated with elevated alpha2 (I) collagen mRNA levels. These results suggest that the elevated production of collagen type I by scleroderma fibroblasts results from overexpression of TGF-beta receptors.
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PMID:Increased expression of TGF-beta receptors by scleroderma fibroblasts: evidence for contribution of autocrine TGF-beta signaling to scleroderma phenotype. 942 86

Excessive accumulation of fibrillar collagens is a hallmark of the cutaneous fibrosis in both systemic and localized scleroderma. Turnover of the collagenous extracellular matrix is dependent on the balance between collagenolytic matrix metalloproteinases and their specific inhibitors. We have examined the expression of the novel, matrix associated tissue inhibitor of metalloproteinases-3 (TIMP-3) in normal and scleroderma skin fibroblasts in culture and in vivo. The levels of TIMP-3 mRNA were elevated up to 2.5-fold in five of seven systemic sclerosis fibroblast strains, whereas TIMP-1 mRNA expression was elevated up to 1.8-fold in two and TIMP-2 mRNA expression up to 1.8-fold in two systemic sclerosis strains. Using in situ hybridization, TIMP-3 mRNA was detected in seven of 12 localized scleroderma skin samples, specifically in fibroblasts within fibrotic collagen fibers or in the vicinity of inflammatory cells. TIMP-1 mRNA was detected in three of eight scleroderma skin samples in fibroblasts adjacent to inflammatory cells. The expression of TIMP-3 mRNA by systemic sclerosis and normal skin fibroblasts was enhanced to a similar extent (by 8.6- and 8.1-fold, respectively) by transforming growth factor-beta, and suppressed down to 34 and 54%, respectively, by tumor necrosis factor-alpha. Specific activation of TIMP-3 gene expression in scleroderma skin fibroblasts in culture and in vivo suggests a role for TIMP-3 in the pathogenesis of dermal fibrosis via inhibition of turnover of fibrotic dermal extracellular matrix, possibly due to upregulation of TIMP-3 expression by transforming growth factor-beta.
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PMID:Activation of tissue inhibitor of metalloproteinases-3 (TIMP-3) mRNA expression in scleroderma skin fibroblasts. 954 Sep 85

The regulation of matrix biosynthesis in systemic sclerosis has been the focus of many studies, because excessive matrix synthesis causes pathologic changes, and because this would seem to be a good target for therapies aimed at ameliorating the disease. Possible targets for antifibrotic therapies include both matrix gene stimulatory and inhibitory pathways. Much recent progress has been made in understanding the mechanism of action of transforming growth factor-beta (TGF-beta), an important profibrotic cytokine with pleiotropic effects on fibroblasts. It appears that TGF-beta may use multiple signal transduction pathways in fibroblasts and it is possible that defects in any of these pathways may result in an abnormal response to TGF-beta, resulting in fibrosis. Studies on negative regulation of matrix gene expression have singled out the antifibrotic cytokines tumor necrosis factor-alpha and interferon-gamma. Finally, a new approach that compares mRNA expression in normal versus diseased fibroblasts has already lead to the discovery of genes that may play a role in the development of fibrosis. This represents an important advance because genes can be identified that have not previously been implicated in the control of matrix synthesis, and thus might not otherwise have been studied in this context.
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PMID:Regulation of matrix biosynthesis and degradation in systemic sclerosis. 1109 4

Scleroderma is a disorder characterized by fibrosis of the skin and internal organs and autoimmunity. Whereas the cause is unknown, interleukin-4 and transforming growth factor-beta have been postulated to play a major part in the fibrosis. To investigate the part played by these cytokines, we prepared TSK/+ mice with a targeted mutation in the interleukin-4R alpha or transforming growth factor-beta genes. The breeding failed to produce TSK/+ transforming growth factor-beta -/- mice so analysis of the role of transforming growth factor-beta was limited to TSK/+ transforming growth factor-beta +/- mice. We observed that TSK/+ interleukin-4R alpha -/- did not develop dermal thickening, and deletion of one allele of the transforming growth factor-beta gene resulted in diminished dermal thickness compared with TSK/+ mice; however, the deletion of interleukin-4R alpha or transforming growth factor-beta had no effect on lung emphysema, which is another characteristic of TSK syndrome. Electron microscopic analysis of skin showed that the collagen fibrils in TSK/+ interleukin-4R alpha -/- mice exhibit normal periodicity but have a smaller diameter than the fibers found in C57BL/6 mice. Analysis of skin and serum samples showed that the deletion of interleukin-4R alpha or one allele of transforming growth factor-beta prevented the increase of skin thickness paralleled with a decrease in the dermal hydroxyproline content and development of autoantibodies associated with TSK syndrome. These results demonstrate the importance of interleukin-4 and transforming growth factor-beta for the development of cutaneous fibrosis in vivo and suggest an important part for these cytokines in wound healing and connective tissue maintenance in general.
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PMID:Lack of skin fibrosis in tight skin (TSK) mice with targeted mutation in the interleukin-4R alpha and transforming growth factor-beta genes. 1116 9

Systemic sclerosis (SSc) is a connective tissue disease with unknown etiology characterized by excessive deposition of collagen in the skin as well as various internal organs. One of the characteristic histological features is the presence of infiltrating mononuclear cells in the dermis in its early stage. As well as T cells, macrophages are implicated to play an important role in the initial pathologic changes associated with SSc by releasing fibrogenic cytokines, including transforming growth factor-beta or platelet-derived growth factor. However, the precise mechanism for increased monocyte/macrophage recruitment in the lesional skin of SSc is still not completely elucidated. Monocyte chemoattractant protein-1 (MCP-1) is a predominant monocyte chemoattractant secreted by various cells types including mononuclear cells, fibroblasts, smooth muscle cells, endothelial cells, or keratinocytes. In this study, we examined the expression of MCP-1 protein and mRNA in the lesional skin of seven patients with SSc by immunohistochemistry and in situ hybridization. Results of immunohistochemistry showed that MCP-1 was detected on infiltrating mononuclear cells and fibroblastic cells in scleroderma skin, whereas normal skin showed only minimal MCP-1 expression. We demonstrated the expression of MCP-1 mRNA in infiltrating mononuclear cells and keratinocytes in scleroderma and contact dermatitis skin. In addition, signals were also detected in fibroblasts in the lesional skin of scleroderma, whereas fibroblasts in normal skin and contact dermatitis skin did not express MCP-1 mRNA. These findings suggest that MCP-1 plays a role in recruiting monocyte/macrophages in the lesional skin of scleroderma and that activated fibroblasts in scleroderma are involved in this process.
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PMID:Expression of monocyte chemoattractant protein-1 in the lesional skin of systemic sclerosis. 1137 30

Scleroderma is a connective tissue disorder with unknown etiology. Myofibroblasts appear during fibrotic processes such as scleroderma, hypertrophic scarring, and wound healing. We previously established a mouse model for scleroderma by local injections of bleomycin. To determine the phenotype of the fibroblasts in sclerotic skin after bleomycin treatment, we examined the expression of alpha-smooth muscle actin (alpha-SMA), a marker for myofibroblasts, in lesional skin as well as in fibrous lung in this model. Dermal sclerosis was induced by daily local injections of bleomycin (100 microg/ml) for 3 weeks in C3H mice. Immunohistochemical examination showed that alpha-SMA-reactive cells were detectable on fibroblastic cells in bleomycin-injected skin at 1 week. There was a significant increase in the immunoreactive fibroblastic cells for alpha-SMA in lesional skin in parallel with the induction of dermal sclerosis. After 3 weeks' treatment with bleomycin, the number of alpha-SMA-reactive fibroblasts showed an 11-fold increase compared with that in control PBS-treated mice. alpha-SMA-positive cells were also detected in lung parenchyma after bleomycin treatment. Following concomitant treatment with anti-transforming growth factor-beta (TGF-beta) antibody with bleomycin, the number of alpha-SMA-positive fibroblastic cells was significantly reduced up to 50%, along with the reduction of dermal sclerosis. To confirm the protein level of alpha-SMA, immunoblotting was carried out. Results showed an increase of alpha-SMA expression in lesional skin at 3 weeks of bleomycin treatment, which was reduced following anti-TGF-beta antibody treatment. These data suggest that fibroblastic cells are phenotypically altered into myofibroblasts during the fibrotic process in the experimental model of bleomycin-induced scleroderma, which was considered mediated, for the most part, by TGF-beta. Blockade of TGF-beta may be a therapeutic intervention for scleroderma.
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PMID:Animal model of sclerotic skin. V: Increased expression of alpha-smooth muscle actin in fibroblastic cells in bleomycin-induced scleroderma. 1178 Oct 70


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