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

Recent investigations of immunologic events in systemic sclerosis focus on the identification of which immune system cells are participating in the disease process, what antigens are stimulating the T and B cells, which cytokines are involved, and which cell adhesion molecules promote cell-cell and cell-extracellular matrix interactions. Increased numbers of gamma/delta and activated CD4+ T cells are present in involved skin of line-200 chickens, an animal model of systemic sclerosis. CD4+ T cells from patients with systemic sclerosis are stimulated by human type I collagen, and immunoglobulins from some patients with systemic sclerosis bind retroviral proteins, the terminal galactosyl (alpha 1-3)-galactose disaccharide of laminin, or a 138 amino acid region of the PM-Scl antigen. The development of an anticentromere antibody response in patients with systemic sclerosis appears to require the presence of a polar amino acid at position 26 in the antigen-binding cleft of the HLA-DQB1 molecule. Interleukin-2, interleukin-4, interleukin-6, and transforming growth factor-beta have been implicated as cytokines that may be involved in the pathogenesis of systemic sclerosis. Increased expression of intercellular adhesion molecule 1 (ICAM-1) on systemic sclerosis fibroblasts is responsible for increased binding of T cells to those fibroblasts through ICAM-1/lymphocyte function-associated antigen 1 interactions. beta 1 and beta 2 integrins, ICAM-1, and endothelial leukocyte adhesion molecule 1 all may be involved in the homing of lymphocytes to involved skin in patients with systemic sclerosis.
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PMID:Immunologic aspects of scleroderma. 145 82

Scleroderma fibrotic lesions demonstrate vascular disease, mononuclear cell infiltrates, and increased collagen. Fibroblasts in these lesions are activated to synthesize increased extracellular matrix substances, a phenotype that continues when these cells are removed and grown in tissue culture. Levels of messenger RNA for connective-tissue substances, measured directly in biopsies of scleroderma skin, show increased message for type I collagen, but not type III collagen or fibronectin. Increased procollagen type I in scleroderma skin occurs in the papillary dermis, perivascular areas, and deep interstitium, even in skin areas that are not yet fibrotic. Scleroderma fibroblasts express more intercellular adhesion molecule 1 on their surfaces than do normal cells, and this molecule is increased in endothelial cells, mononuclear cells, and fibroblasts. In vitro scleroderma fibroblasts adhere more frequently to extracellular matrix substances and retract collagen lattices to a greater extent. Peripheral blood lymphocytes from scleroderma patients produce excessive amounts of interleukin-2 when incubated with type I collagen, and circulating basophils release more histamine than do normal cells. There is evidence for activated eosinophils both in the dermis and pulmonary lesions in scleroderma, which may play a role in fibrosis. Transforming growth factor-beta is overexpressed by alveolar macrophages from patients with fibrotic pulmonary disease. Scleroderma fibroblasts, when exposed to transforming growth factor-beta, overexpress the alpha-type receptor for platelet-derived growth factor. Scleroderma sera more frequently contain measurable quantities of interleukin-4, interleukin-6, and interleukin-2. Interleukin-4 causes adult dermal fibroblasts to proliferate and to make interleukin-6. Interleukin-6 has been shown to stimulate fibroblast synthesis of collagen and glycosaminoglycans.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Connective tissue metabolism including cytokines in scleroderma. 145 83

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.
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PMID:Increased adhesion of fibroblasts from patients with scleroderma to extracellular matrix components: in vitro modulation by IFN-gamma but not by TGF-beta. 172 42

Fibroblasts within the skin of scleroderma patients constitute a phenotypically heterogeneous population with regard to expression of collagens, cytokines, and cytokine receptors. By in situ hybridization techniques, scleroderma skin is shown to contain a subpopulation of fibroblasts that are stimulated for expression of type VI collagen; the size of this subpopulation is larger than that found in normal skin. The heterogeneity in collagen production among scleroderma fibroblasts can also be demonstrated in vitro following sorting by flow cytometric analysis. An isoform of a cytokine known to be a potent modulator of collagen expression, transforming growth factor-beta 2, is overexpressed in and around inflammatory infiltrates in biopsies of skin from scleroderma patients. Scleroderma fibroblasts grown in culture express slightly elevated levels of transcripts for transforming growth factor-beta 1, demonstrated by Northern analysis. Osteonectin, or SPARC (secreted protein, acidic and rich in cysteine), messenger RNA is also clearly elevated in fibroblasts cultured from the affected skin of scleroderma patients. The affinity of epidermal growth factor receptors on fibroblasts derived from the skin of scleroderma patients is decreased compared with that of receptors on normal fibroblasts. Platelet-derived growth factor-beta receptors were detectable by immunohistochemical staining in dermal vessels and surrounding fibroblasts in 13 of 14 biopsies of skin of scleroderma patients, whereas they were absent in sections of normal skin. These studies completed within the past year allow recognition of the importance of interactions between cell types, and the possible consequences of alterations in cytokine secretory patterns and cell responsiveness.
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PMID:Connective tissue metabolism including cytokines in scleroderma. 177 50

To determine whether enhanced matrix synthesis by systemic sclerosis (SSc) fibroblasts in vitro is due to increased responsiveness to transforming growth factor-beta (TGF-beta), fibronectin release by SSc and normal fibroblasts (7 pairs) was measured at various concentrations of TGF-beta. In the absence of TGF-beta, SSc fibroblasts released 30 +/- 22% more fibronectin than normal fibroblasts. While both SSc and normal fibroblasts increased fibronectin release at all concentrations of TGF-beta tested, the percentage increases were not statistically greater for the SSc fibroblasts even though 4 of the SSc fibroblasts strains were selectively sensitive to low concentrations of TGF-beta. TGF-beta increased cell numbers of both SSc and normal strains equally. Our data confirm abnormal regulation of fibronectin gene expression in SSc fibroblasts and suggest increased sensitivity to TGF-beta by some SSc fibroblast strains.
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PMID:Fibronectin release by systemic sclerosis and normal dermal fibroblasts in response to TGF-beta. 202 18

The cause of systemic sclerosis remains unknown, but cellular and molecular mechanisms possibly responsible for the characteristic clinical manifestations of fibrosis and vascular damage (Raynaud's phenomenon, telangiectasis, digital infection, and renal arteriopathy) are becoming understood in greater detail. One possibly important cytokine is transforming growth factor-beta (TGF-beta); its involvement is reviewed here. With regard to vascular lesions, TGF-beta has variably been shown to inhibit endothelial cell growth in vitro but to promote angiogenesis in vivo, a paradox that remains unresolved. Nonetheless, an injurious activity of TGF-beta on microvascular endothelial cells could help to explain the intimal proliferation and microvascular obliteration seen. Whether as a result of or as a cause of endothelial cell damage, platelet activation has been well documented in systemic sclerosis and the platelet alpha granule pool contains a large quantity of TGF-beta. TGF-beta is also produced by activated macrophages and T cells, both of which are known to occur within systemic sclerosis lesions. An important effect of TGF-beta is its stimulation of fibroblast collagen and fibronectin synthesis and their deposition into the extracellular matrix. Stimulation by TGF-beta may therefore account for the fibrosis seen in the dermis and in the internal organs. Direct evidence of TGF-beta involvement in systemic sclerosis is scanty, and awaits discovery of either an abnormal expression of or response to TGF-beta. The biologic effects of TGF-beta appear to be regulated at the level of activation from a latent polypeptide precursor form. Descriptions of the importance of this cytokine in pathologic conditions will need to account for this activation and its regulation. Nonetheless, the physiologic effects so far attributed to TGF-beta make its involvement in systemic sclerosis an attractive possibility to explain some of the manifestations of this enigmatic disease.
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PMID:A possible role for transforming growth factor-beta in systemic sclerosis. 225 29

The role of some growth factors and cytokines in the pathogenesis of systemic sclerosis (SSc) has been suggested. In particular, the contribution of transforming growth factor beta in the progression of skin sclerosis is suspected. Connective tissue growth factor (CTGF) was originally identified in human umbilical vein endothelial cells, and a recent study has revealed that human skin fibroblasts produce CTGF after stimulation with transforming growth factor beta. In the present study, the distribution of CTGF gene expression in tissue sections from patients with SSc was investigated by digoxigenin-labeled in situ hybridization. Strong CTGF mRNA signals were observed in the fibroblasts in sclerotic lesions, especially in the deep dermis, of the skin specimens from patients with SSc, whereas there was no expression in the skin from normal controls. The number of fibroblasts with positive hybridization signals was more abundant in the dermis from the sclerotic stage than in that from the inflammatory stage. Our findings indicate 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 SSc, because transforming growth factor beta is the only inducer for CTGF identified to date.
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PMID:Significant correlation between connective tissue growth factor gene expression and skin sclerosis in tissue sections from patients with systemic sclerosis. 763 14

Excessive connective tissue deposition in the skin and other organs is the pathologic hallmark of systemic sclerosis (SSc), and fibrosis accounts for much of the chronic morbidity of this disease. Unregulated production of collagen in SSc skin fibroblasts has been demonstrated both in vivo and in vitro, and is considered to be a critical process in the development of fibrosis. In addition to collagen, other components of the extracellular matrix are also overexpressed in SSc fibroblasts, and may be important in the functional alterations of connective tissue. The transcriptional activity of several genes coding for matrix macromolecules is upregulated in SSc fibroblasts. The pleiotropic signaling molecule transforming growth factor-beta (TGF beta) is likely to be intimately involved in initiating and perhaps perpetuating the fibrotic response in SSc. TGF beta, a potent profibrotic cytokine, is highly expressed in endothelial cells, in fibroblasts near blood vessels, and in perivascular inflammatory cells in involved tissues in SSc. The apparent failure of SSc fibroblasts to down-regulate their collagen synthesis when cultured in a three-dimensional matrix suggest an additional mechanism for the maintenance of unregulated collagen production in these cells. Finally, subpopulations of fibroblasts with an activated biosynthetic phenotype may become dominant in SSc. Therefore, persistent elevation of extracellular matrix gene expression in SSc tissues may be the result of a series of events representing the interaction of genetic and hormonal factors. A precise delineation of the mechanisms of fibroblast activation is needed for understanding the pathogenesis of SSc, and for the rational design of therapeutic interventions aimed at interfering with the fibrotic process.
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PMID:Regulation of connective tissue synthesis in systemic sclerosis. 765 Apr 21

Many distinct areas of investigation contribute to the understanding of immune abnormalities in systemic sclerosis. Recent immunohistochemical studies question the causal relationship of increased transforming growth factor-beta expression to dermal fibrosis. RNA polymerase I, II, and III have been identified as autoantigens specific for systemic sclerosis. Anti-RNA polymerase antibodies are directed against both unique and shared subunits of the multiprotein complexes. The targeting of several subunits suggests that the entire complexes are processed and presented by antigen-presenting cells. Genetic studies show that both HLA-DR and HLA-DQ genes control the antitopoisomerase response in Japanese patients. The null allele of the complement component C4 and HLA-DQA2 have been identified as two independent disease susceptibility genes.
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PMID:Immunologic aspects of scleroderma. 786 82

We investigated the expression of transforming growth factor-beta (TGF-beta) isoforms in involved and uninvolved areas of skin from patients with systemic sclerosis (SSc) and normal controls. Paraffin-embedded skin specimens were stained for TGF-beta 1, TGF-beta 2, and TGF-beta 3 using the avidin-biotin-peroxidase technique. TGF-beta 2 was expressed intensely in the extracellular matrix of the skin biopsies obtained from involved areas of patients with SSc, in contrast to the uninvolved areas and normal individuals. TGF-beta 2 was deposited throughout the entire dermis and also in a linear fashion along the dermoepidermal junction and in the perivascular areas of SSc-involved skin. Although infiltrating mononuclear cells were not present in great numbers, they did not stain for TGF-beta 2. TGF-beta 1 and TGF-beta 3 were not expressed in the extracellular space in either patients or normal controls, except in rare cases. The cellular staining which was observed for all three isoforms did not differ between involved and uninvolved skin and normal controls. The finding of increased deposition of TGF-beta 2 in the involved skin of patients with SSc implies that it may be involved in the pathologic fibrotic process.
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PMID:Immunohistological demonstration of transforming growth factor-beta isoforms in the skin of patients with systemic sclerosis. 840 57


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