Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0039483 (giant cell arteritis)
 3,204 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Molecular techniques have provided new tools to define genetic systems involved in disease susceptibility and to dissect molecular events driving inflammatory reactions. Inflammatory infiltrates in the wall of large and medium-sized arteries, sometimes associated with giant cell formation, are pathognomic for Takayasu's arteritis (TA) and giant cell (cranial) arteritis. Molecular techniques have been used successfully to define genetic host factors involved in disease susceptibility and to dissect the nature of inflammatory cells and mediators in the pathologic lesions. Careful analysis of incidence data for TA suggests that TA is a worldwide disease. Genetic comparison of western and eastern TA, however, raises the possibility of disease heterogeneity. Emerging data indicate that HLA-DRB1 genes represent important risk factors in giant cell arteritis. Whether disease association is related to the role of HLA-DR molecules in presenting a disease-inducing antigen remains to be seen. Analysis of the molecular diversity of tissue-infiltrating T cells indicates that a small proportion of CD4+ T cells proliferate in situ, potentially as a result of antigen recognition. Tissue cytokine profiles reveal functional selection of T cells and are compatible with the model that Th1 cells recognize antigen on the surface of activated macrophages. The presence of T cell-derived cytokines in temporal artery tissue of patients with polymyalgia rheumatica who are lacking microscopic inflammation indicates subclinical vasculitis.
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PMID:Molecular approaches toward pathologic mechanisms in giant cell arteritis and Takayasu's arteritis. 771 19

Leukaemia inhibitory factor (LIF) is a cytokine which possesses a wide range of biological activities including, like IL-6, the capacity to stimulate acute phase protein (APP) synthesis. We have developed a sensitive and specific ELISA for human LIF, and tested the circulating cytokine levels in various disease states, some of which are associated with inflammation. LIF was detected in 11/20 sera from patients with giant cell arteritis (GCA), a vasculitis syndrome affecting particularly the temporal artery, characterized by panarteritis with inflammatory cell infiltration. LIF levels were considerably elevated in some patients who also displayed elevated levels of IL-6 and C-reactive protein (CRP); however, no correlation was observed between the levels of circulating LIF and levels of IL-6 or CRP. Furthermore, LIF levels were not affected by corticosteroid therapy, whereas IL-6 and CRP decreased rapidly, as clinical symptoms resolved. A putative role for LIF in the persistence of histological lesions is discussed. This is the first report of the presence of circulating LIF in sera. These results are in agreement with the complexity of induced inflammatory cytokines and corticoid regulation of APP synthesis observed in vitro and in vivo.
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PMID:High circulating leukaemia inhibitory factor (LIF) in patients with giant cell arteritis: independent regulation of LIF and IL-6 under corticosteroid therapy. 809 3

IL-6 serum levels are increased in patients suffering from GCA, and this cytokine may play a role in the systemic symptoms associated with this disease. We analyzed by in situ hybridization and immunohistochemistry whether IL-6 production originates from arterial granulomas in GCA. Seven arterial biopsy specimens taken from patients with histologically proved GCA were studied. IL-6 production was detected in all cases at both the mRNA and the protein levels. IL-6-producing cells were distributed in the intima, in the media, and in the adventitia. Positive cells were clearly enriched in the media, however, and particularly in contact with the internal elastic lamina. The morphology of the IL-6-producing cells showed that they belonged to several cell populations. In the media, most IL-6-producing cells were macrophages, whereas fibroblasts also produced IL-6 in the intima. Neither endothelial cells nor giant cells were found to express the IL-6 gene. Increased IL-6 serum concentrations returned to normal levels in most patients after administration of corticosteroids, indicating that inhibition of IL-6 production by GCA granuloma cells may be one of the mechanisms of action of corticosteroids in this condition. Production of IL-6 in abnormal arteries may thus participate to the systemic manifestations of GCA.
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PMID:Production of interleukin 6 by granulomas of giant cell arteritis. 818 59

The Gfi-1 proto-oncogene encodes a zinc finger protein with six C2H2-type, C-terminal zinc finger motifs and is activated by provirus integration in T-cell lymphoma lines selected for interleukin-2 independence in culture and in primary retrovirus-induced thymomas. Gfi-1 expression in adult animals is restricted to the thymus, spleen, and testis and is enhanced in mitogen-stimulated splenocytes. In this report, we show that Gfi-1 is a 55-kDa nuclear protein that binds DNA in a sequence-specific manner. The Gfi-1 binding site, TAAATCAC(A/T)GCA, was defined via random oligonucleotide selection utilizing a bacterially expressed glutathione S-transferase-Gfi-1 fusion protein. Binding to this site was confirmed by electrophoretic mobility shift assays and DNase I footprinting. Methylation interference analysis and electrophoretic mobility shift assays with mutant oliginucleotides defined the relative importance of specific bases at the consensus binding site. Deletion of individual zinc fingers demonstrated that only zinc fingers 3, 4, and 5 are required for sequence-specific DNA binding. Potential Gfi-1 binding sites were detected in a large number of eukaryotic promoter-enhancers, including the enhancers of several proto-oncogenes and cytokine genes and the enhancer of the human cytomegalovirus (HCMV) major immediate-early promoter, which contains two such sites. HCMV major immediate-early-chloramphenicol acetyltransferase reporter constructs, transfected into NIH 3T3 fibroblasts, were repressed by Gfi-1, and the repression was abrogated by mutation of critical residues in the two Gfi-1 binding sites. These results suggest that Gfi-1 may play a role in HCMV biology and may contribute to oncogenesis and T-cell activation by repressing the expression of genes that inhibit these processes.
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PMID:Gfi-1 encodes a nuclear zinc finger protein that binds DNA and functions as a transcriptional repressor. 875

Several disease mechanisms have been studied in the model of GCA. GCA patients exhibit a genetic susceptibility which has been mapped to the HLA-DRB1 gene. Polymorphic amino acid residues localized at the floor of the antigen binding site are highly selected in GCA patients suggesting a role for antigen binding and presentation in the disease. This and other genetic risk factors might actually be a surrogate for the distinct geographic distribution of the disease with a marked preference for Northern Europe. Studies on functional aspects of T cells accumulating in the vasculitic foci have demonstrated a strong bias for Th1 helper T cells which locally release IL-2 and IFN-gamma. IFN-gamma appears to be a key cytokine in this vasculitis. IFN-gamma producing T cells represent a minority of the tissue infiltrating cell population suggesting that very few cells have disease relevance and the majority of T cells is recruited as bystanders. IFN-gamma secreting CD4 T cells preferentially localize to the adventitial-medial junction and are thus placed distant from the center of pathology, the intima and internal media. TCRs expressed by T cells accumulated in the affected tissue are not randomly distributed but are biased toward selected specificities. These selected T cells undergo proliferation in the tissue and can be isolated from nonadjacent and independent sites of the vasculitis. This distribution pattern indicates a common driving factor, suspected to be a tissue residing antigen [8]. Further support for an antigen driving this pathological T cell response comes from the finding that temporal artery specimens engrafted into SCID mice continue to show the typical disease process indicating that all components relevant for the disease are contained in the temporal artery wall. So far no shared TCR utilized by different patients has been identified, raising the question whether distinct antigens can elicit GCA as a common pathway of reactivity. Besides its role in investigating pathomechanisms the SCID mouse model of GCA provides the unique opportunity to study the therapeutic effects of established and novel treatments. It can be expected that some of the pathogenic rules established for GCA can be applied to other vasculitic syndromes.
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PMID:The pathogenic role of T lymphocytes in vasculitis. 894 85

Giant cell arteritis (GCA) is a vasculitic syndrome that preferentially affects medium and large-sized arteries. Glucocorticoid therapy resolves clinical symptoms within hours to days, but therapy has to be continued over several years to prevent disease relapses. It is not known whether and how glucocorticoids affect the function of the inflammatory infiltrate or why the disease persists subclinically despite chronic treatment. GCA is self-sustained in temporal arteries engrafted into SCID mice, providing a model in which the mechanisms of action and limitations of glucocorticoid therapy can be examined in vivo. Administration of dexamethasone to temporal artery-SCID chimeras for 1 wk induced a partial suppression of T cell and macrophage function as indicated by the reduced tissue concentrations of IL-2, IL-1beta, and IL-6 mRNA, and by the diminished expression of inducible NO synthase. In contrast, synthesis of IFN-gamma mRNA was only slightly decreased, and expression of TGF-beta1 was unaffected. These findings correlated with activation of the IkappaBalpha gene and blockade of the nuclear translocation of NFkappaB in the xenotransplanted tissue. Dose-response experiments suggested that steroid doses currently used in clinical medicine are suboptimal in repressing NFkappaB-mediated cytokine production in the inflammatory lesions. Chronic steroid therapy was able to deplete the T cell products IL-2 and IFN-gamma, whereas the activation of tissue-infiltrating macrophages was only partially affected. IL-1beta transcription was abrogated; in contrast, TGF-beta1 mRNA synthesis was steroid resistant. The persistence of TGF-beta1-transcribing macrophages, despite paralysis of T cell function, may provide an explanation for the chronicity of the disease, and may identify a novel therapeutic target in this inflammatory vasculopathy.
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PMID:Glucocorticoid-mediated repression of cytokine gene transcription in human arteritis-SCID chimeras. 918 6

Inflammation of the arterial wall in giant cell arteritis induces a series of structural changes, including the formation of new vasa vasorum. To study the regulation of neoangiogenesis in giant cell arteritis, temporal arteries were examined for the extent and localization of microvessel generation and for the production of angiogenic factors. In normal arteries, vasa vasorum were restricted to the adventitia, but in inflamed arteries, capillaries emerged in the media and the intima. These capillaries displayed a distinct topography with a circumferential arrangement in the external one-third of the intima. Neovascularization was closely correlated with the formation of lumen-obstructing intima, the fragmentation of the internal elastic lamina, and the presence of multinucleated giant cells. Comparison of tissue cytokine transcription in temporal arteries of giant cell arteritis patients with and without up-regulated neoangiogenesis identified interferon-gamma and vascular endothelial growth factor but not fibroblast growth factor-2 as mediators associated with vasa vasorum proliferation. Giant cells and CD68-positive macrophages at the media-intima junction were found to be the major cellular sources of vascular endothelial growth factor. These data demonstrate that formation of new vasa vasorum in vasculitis is regulated by inflammatory cells and not by arterial wall cells, raising the possibility that it represents a primary disease mechanism and not a secondary hypoxia-induced event. Increased neovascularization in interferon-gamma-rich arteries suggests that the formation of new vasa vasorum is determined by the nature of the immune response in the arterial wall, possibly resulting from the generation and functional activity of multinucleated giant cells.
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PMID:Formation of new vasa vasorum in vasculitis. Production of angiogenic cytokines by multinucleated giant cells. 1048 34

Giant cell arteritis (GCA) is the commonest primary systemic vasculitis in the United States. Severe outcomes include blindness and stroke, and death may result from aortic dissection. Temporal artery biopsy remains the gold standard for diagnosis. Magnetic resonance imaging (MRI) of involved vessels shows promise as a useful noninvasive method for diagnosis and assessment of disease activity. Corticosteroid therapy is effective but is associated with considerable morbidity. Longitudinal studies with large numbers of patients are required to identify appropriate steroid-sparing agents. New insights into the immunopathogenesis of GCA have allowed us to identify heterogeneous subsets of patients with varying clinical presentations corresponding to specific cytokine profiles. The concept of the involved artery as an active participant in the events leading to luminal obstruction has been realized and provides the opportunity to evaluate novel therapies to modify the course of the disease.
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PMID:Spectrum of giant cell vasculitis. 1112 88

Giant cell arteritis (GCA), the most common form of systemic vasculitis in adults, preferentially involves large and medium-sized arteries in patients over the age of 50. The classic manifestations are headache, jaw claudication, polymyalgia rheumatica (PMR), and visual symptoms, but 40% of patients present with a wide range of occult manifestations. Early diagnosis and treatment with prednisone can prevent blindness, the most feared complication of GCA. The pathogenesis of GCA is T-cell dependent and antigen driven. Clinical subsets of GCA appear to result from variable cytokine expression. The risk of developing thoracic aortic aneurysm is increased more than 17-fold in patients with GCA. GCA can also involve large arteries, especially the subclavian and axillary arteries. Color Doppler ultrasound, magnetic resonance imaging, and positron-emission tomography scanning are providing insights into the extent and pathogenesis of the disease but have not replaced temporal artery biopsy as the gold standard for securing the diagnosis. Two recently completed double-blind, placebo-controlled trials concerning whether methotrexate plus prednisone is more effective than prednisone alone reached conflicting conclusions.
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PMID:Giant cell arteritis. 1179 Sep 89

Cytokines are small proteins that serve as chemical messengers between cells, regulating cell growth and differentiation, tissue repair and remodeling, and many aspects of the immune response. Cytokines are instrumental in determining the nature, magnitude, and duration of inflammatory reactions and, as such, represent ideal targets for interfering with pathogenic processes. In OCA and PMR, cytokines are encountered in two locations, the inflammatory infiltrates accumulating in the arterial wall and in the circulation. IL-6, a cytokine involved in stimulating acute-phase responses, is located upstream of many of the laboratory abnormalities considered helpful in diagnosing and managing GCA/PMR, including elevated ESR and CRP. IL-6 has the potential to be helpful in predicting disease severity and may allow for a tailoring of immunosuppressive therapy. There is evidence suggesting that IL-6 outperforms other chemical markers in detecting disease activity and could, therefore, have a role in monitoring treatment. Interesting pathogenic clues have been derived from studies of cytokines produced in the vascular lesions. IFN-gamma has emerged as a key regulator in determining the nature and direction of the inflammatory response. IFN-gamma appears to be critically involved in modulating the process of intimal hyperplasia, the most destructive consequence of vasculitis, and, as such, emerges as a prime target for novel therapeutic approaches.
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PMID:Cytokines in giant-cell arteritis. 1208 74


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