RESUMO
Narcolepsy is a rare brain disorder that reflects a selective loss or dysfunction of orexin (also known as hypocretin) neurons of the lateral hypothalamus. Narcolepsy type 1 (NT1) is characterized by excessive daytime sleepiness and cataplexy, accompanied by sleep-wake symptoms, such as hallucinations, sleep paralysis and disturbed sleep. Diagnosis is based on these clinical features and supported by biomarkers: evidence of rapid eye movement sleep periods soon after sleep onset; cerebrospinal fluid orexin deficiency; and positivity for HLA-DQB1*06:02. Symptomatic treatment with stimulant and anticataplectic drugs is usually efficacious. This Review focuses on our current understanding of how genetic, environmental and immune-related factors contribute to a prominent (but not isolated) orexin signalling deficiency in patients with NT1. Data supporting the view of NT1 as a hypothalamic disorder affecting not only sleep-wake but also motor, psychiatric, emotional, cognitive, metabolic and autonomic functions are presented, along with uncertainties concerning the 'narcoleptic borderland', including narcolepsy type 2 (NT2). The limitations of current diagnostic criteria for narcolepsy are discussed, and a possible new classification system incorporating the borderland conditions is presented. Finally, advances and obstacles in the symptomatic and causal treatment of narcolepsy are reviewed.
Assuntos
Encéfalo/fisiopatologia , Narcolepsia , Orexinas/fisiologia , Humanos , Hipotálamo/fisiopatologia , Narcolepsia/diagnóstico , Narcolepsia/etiologia , Narcolepsia/fisiopatologia , Narcolepsia/terapiaRESUMO
OBJECTIVES: To assess whether the discrepancy between the strong antifibrotic effects of tyrosine kinase inhibitors (TKIs) in animal models and the inconsistent results in clinical studies might be related to the activation levels of drug targets. METHODS: Skin sections of bleomycin, TSK1, Fra-2 transgenic mice, SSc patients and controls were analysed by histology and immunohistochemistry. Subgroups of mice were treated with the TKIs nilotinib or imatinib. Differences in the activation levels of the TKI targets p-PDGFRß (platelet derived growth factor ß) and p-c-abl were assessed. RESULTS: In bleomycin and TSK1 mice, expression of activated p-PDGFRß (platelet derived growth factor receptor ß) and p-c-abl was ubiquitous with strong upregulation compared with controls. Treatment with TKIs resulted in successful target inhibition and consequently reduced dermal fibrosis. In the Fra-2 model, the activation levels of p-PDGFRß and p-c-abl were much lower than in the bleomycin and the TSK1 models. Accordingly, nilotinib did not prevent dermal fibrosis and target inhibition was unsuccessful. Notably, in skin biopsies of SSc patients, the mean activation levels of TKI targets were only moderate and in the majority of patients resembled those of the non-responsive Fra-2 model. CONCLUSIONS: Animal models for proof-of-concept studies should be selected based on a similar activation level and expression pattern of drug targets as in human SSc.
Assuntos
Inibidores de Proteínas Quinases/uso terapêutico , Proteínas Tirosina Quinases/antagonistas & inibidores , Escleroderma Sistêmico/tratamento farmacológico , Pele/patologia , Adulto , Animais , Benzamidas/uso terapêutico , Biópsia , Bleomicina , Modelos Animais de Doenças , Avaliação Pré-Clínica de Medicamentos/métodos , Feminino , Fibrose , Antígeno 2 Relacionado a Fos/genética , Humanos , Mesilato de Imatinib , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Pessoa de Meia-Idade , Terapia de Alvo Molecular/métodos , Piperazinas/uso terapêutico , Proteínas Serina-Treonina Quinases/genética , Proteínas Proto-Oncogênicas c-abl/metabolismo , Proteínas Proto-Oncogênicas c-sis/metabolismo , Pirimidinas/uso terapêutico , Escleroderma Sistêmico/metabolismo , Escleroderma Sistêmico/patologia , Pele/metabolismo , Resultado do TratamentoRESUMO
MicroRNA (miRNA) species (miR) regulate mRNA translation and are implicated as mediators of disease pathology via coordinated regulation of molecular effector pathways. Unraveling miR disease-related activities will facilitate future therapeutic interventions. miR-155 recently has been identified with critical immune regulatory functions. Although detected in articular tissues, the functional role of miR-155 in inflammatory arthritis has not been defined. We report here that miR-155 is up-regulated in synovial membrane and synovial fluid (SF) macrophages from patients with rheumatoid arthritis (RA). The increased expression of miR-155 in SF CD14(+) cells was associated with lower expression of the miR-155 target, Src homology 2-containing inositol phosphatase-1 (SHIP-1), an inhibitor of inflammation. Similarly, SHIP-1 expression was decreased in CD68(+) cells in the synovial lining layer in RA patients as compared with osteoarthritis patients. Overexpression of miR-155 in PB CD14(+) cells led to down-regulation of SHIP-1 and an increase in the production of proinflammatory cytokines. Conversely, inhibition of miR-155 in RA synovial CD14(+) cells reduced TNF-α production. Finally, miR-155-deficient mice are resistant to collagen-induced arthritis, with profound suppression of antigen-specific Th17 cell and autoantibody responses and markedly reduced articular inflammation. Our data therefore identify a role of miR-155 in clinical and experimental arthritis and suggest that miR-155 may be an intriguing therapeutic target.
Assuntos
Artrite Experimental/genética , Artrite Experimental/metabolismo , Artrite Reumatoide/genética , Artrite Reumatoide/metabolismo , Mediadores da Inflamação/metabolismo , MicroRNAs/genética , MicroRNAs/metabolismo , Animais , Artrite Experimental/imunologia , Artrite Experimental/patologia , Artrite Reumatoide/imunologia , Artrite Reumatoide/patologia , Sequência de Bases , Estudos de Casos e Controles , Citocinas/biossíntese , Humanos , Inositol Polifosfato 5-Fosfatases , Camundongos , Camundongos Knockout , Osteoartrite/genética , Osteoartrite/imunologia , Osteoartrite/metabolismo , Fosfatidilinositol-3,4,5-Trifosfato 5-Fosfatases , Monoéster Fosfórico Hidrolases/genética , Monoéster Fosfórico Hidrolases/metabolismo , Membrana Sinovial/imunologia , Membrana Sinovial/metabolismo , Membrana Sinovial/patologiaRESUMO
OBJECTIVE: Since transcription factors expressed in osteoclasts are possible targets for regulation of bone destruction in bone disorders, we investigated the expression of the transcription factor FBI-1/OCZF/LRF (in humans, factor that binds to inducer of short transcripts of human immunodeficiency virus type 1; in rats, osteoclast-derived zinc finger; in mice, leukemia/lymphoma-related factor) in patients with rheumatoid arthritis (RA), and assessed its role in osteoclastogenesis in vivo. METHODS: Expression of FBI-1/OCZF was investigated in subchondral osteoclasts in human RA and in rat adjuvant-induced arthritis (AIA) using immunostaining and in situ hybridization, respectively. Transgenic mice overexpressing OCZF (OCZF-Tg) under the control of the cathepsin K promoter were generated, and bone mineral density and bone histomorphometric features were determined by peripheral quantitative computed tomography, calcein double-labeling, and specific staining for osteoclasts and osteoblasts. LRF/OCZF expression and the consequence of LRF inhibition were assessed in vitro with RANKL-induced osteoclast differentiation. RESULTS: FBI-1/OCZF was detected in the nuclei of osteoclasts in rat AIA and human RA. RANKL increased the levels of LRF messenger RNA and nuclear-localized LRF protein in primary macrophages. In OCZF-Tg mice, bone volume was significantly decreased, the number of osteoclasts, but not osteoblasts, was increased in long bones, and osteoclast survival was promoted. Conversely, inhibition of LRF expression suppressed the formation of osteoclasts from macrophages in vitro. CONCLUSION: FBI-1/OCZF/LRF regulates osteoclast formation and apoptosis in vivo, and may become a useful marker and target in treating disorders leading to reduced bone density, including chronic arthritis.
Assuntos
Artrite Experimental/metabolismo , Artrite Reumatoide/metabolismo , Densidade Óssea/fisiologia , Proteínas de Ligação a DNA/metabolismo , Osteoclastos/metabolismo , Ligante RANK/metabolismo , Fatores de Transcrição/metabolismo , Animais , Artrite Experimental/genética , Artrite Reumatoide/genética , Osso e Ossos/metabolismo , Diferenciação Celular , Proteínas de Ligação a DNA/genética , Feminino , Humanos , Macrófagos/metabolismo , Masculino , Camundongos , Camundongos Transgênicos , Osteoblastos/metabolismo , Ligante RANK/genética , Ratos , Fatores de Transcrição/genéticaRESUMO
OBJECTIVE: To evaluate the decrease of cartilage destruction by a novel orally active and specific matrix metalloproteinase 13 (MMP-13) inhibitor in three different animal models of rheumatoid arthritis (RA). MATERIALS AND METHODS: The SCID mouse co-implantation model of RA, the collagen-induced arthritis (CIA) model in mice and the antigen-induced arthritis model (AIA) in rabbits were used. RESULTS: In the SCID mouse co-implantation model, the MMP-13 inhibitor reduced cartilage destruction by 75%. In the CIA model of RA, the MMP-13 inhibitor resulted in a significant and dose-dependent decrease in clinical symptoms as well as of cartilage erosion by 38% (30 mg/kg), 28% (10 mg/kg) and 21% (3 mg/kg). No significant effects were seen in the AIA model. No toxic effects were seen in all three animal models. CONCLUSION: Although several MMPs in concert with other proteinases have a role in the process of cartilage destruction, there is a need for highly selective MMP inhibitors to reduce severe side effects that occur with non-specific inhibitors. Significant inhibition of MMP-13 reduced cartilage erosions in two of three tested animal models of RA. These results strongly support the development of this class of drugs to reduce or halt joint destruction in patients with RA.
Assuntos
Antirreumáticos/uso terapêutico , Artrite Experimental/tratamento farmacológico , Artrite Reumatoide/tratamento farmacológico , Inibidores Enzimáticos/uso terapêutico , Inibidores de Metaloproteinases de Matriz , Administração Oral , Animais , Antirreumáticos/administração & dosagem , Artrite Experimental/enzimologia , Artrite Experimental/patologia , Artrite Reumatoide/enzimologia , Artrite Reumatoide/patologia , Cartilagem Articular/patologia , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Avaliação Pré-Clínica de Medicamentos/métodos , Inibidores Enzimáticos/administração & dosagem , Feminino , Humanos , Masculino , Metaloproteinase 1 da Matriz/metabolismo , Metaloproteinase 13 da Matriz/metabolismo , Camundongos , Camundongos SCID , Coelhos , Membrana Sinovial/enzimologiaRESUMO
The gamma isoform of phosphoinositide 3-kinase (PI3Kgamma) has been viewed as restricted to leukocytes mediating the regulation of chemokine-induced migration and recruitment of neutrophils, monocytes, and macrophages. In line with the observation that PI3Kgamma-deficient mice display defects in adaptive immunity, inhibition of PI3Kgamma reduces synovial inflammation in the collagen-induced arthritis mouse model of inflammatory arthritis [rheumatoid arthritis (RA)], which has been attributed to reduced influx of inflammatory cells. Challenging the concept of leukocyte-restricted PI3Kgamma function, we report here a novel, nonredundant function of PI3Kgamma as an important regulator of fibroblast-induced cartilage destruction during chronic destructive arthritis. We show that in human tumor necrosis factor transgenic mice, the loss of PI3Kgamma leads to a milder inflammatory arthritis. Interestingly, PI3Kgamma deficiency does not alter the recruitment of inflammatory cells, but significantly reduces cartilage damage through reduced expression of matrix metalloproteinases in fibroblasts and chondrocytes. In vitro analyses demonstrate that the decreased invasiveness of fibroblasts is mediated by reduced phosphorylation of Akt and extracellular signal-regulated kinase. Using a PI3Kgamma specific inhibitor, these data are confirmed in human synovial fibroblasts from patients with RA who exhibit a disease-specific up-regulation of PI3Kgamma. Our data indicate that in addition to mediating the recruitment of inflammatory cells, PI3Kgamma is an important regulator of fibroblast-mediated joint destruction in RA and suggest that specific inhibitors of PI3Kgamma will interfere with the activation of RA synovial fibroblasts and reduce cartilage destruction in RA.
Assuntos
Artrite/metabolismo , Cartilagem/patologia , Fosfatidilinositol 3-Quinases/metabolismo , Animais , Artrite/genética , Artrite/patologia , Artrite Reumatoide/metabolismo , Condrócitos/metabolismo , Classe Ib de Fosfatidilinositol 3-Quinase , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Feminino , Fibroblastos/citologia , Fibroblastos/metabolismo , Expressão Gênica/fisiologia , Humanos , Isoenzimas/genética , Isoenzimas/metabolismo , Masculino , Metaloproteases/metabolismo , Camundongos , Camundongos Knockout , Fosfatidilinositol 3-Quinases/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Membrana Sinovial/citologia , Fatores de Tempo , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Advances in the current knowledge of pathogenetic mechanisms of rheumatoid arthritis have contributed to the development of biological therapy, and translated research findings into clinical practice. TNF-alpha (infliximab, etanercept, adalimumab), IL-1 (anakinra) and IL-6 (tocilizumab) inhibitors, a B-cell depleting agent (rituximab) and a drug blocking T-cell costimulation (abatacept) have been approved for rheumatoid arthritis. The progress in manufacturing biotechnology has contributed to the development of several other prospective agents that may form the basis for the therapy of rheumatoid arthritis in the near future. New or modified TNF-alpha inhibitors (golimumab, certolizumab pegol), new monoclonal antibodies against other cytokines (e.g. IL-1, IL-6, IL-12, IL-15, IL-17, IL-23), and other agents targeting B-cell depletion (e.g. ocrelizumab, ofatumumab) are in various stages of development. Many pharmaceutical companies have focused on developing small molecule inhibitors with possible peroral administration, which are considered promising drugs for rheumatoid arthritis. In most cases, these small molecules inhibit cellular kinases (e.g. p38, JAK or Syk) that mediate the signaling and transcription of proinflammatory genes. In this review, we describe the cytokine inhibitors and modulators of the immune response currently in ongoing clinical trials, the results of which may further expand the spectrum of efficient therapies for chronic autoimmune diseases.
Assuntos
Artrite Reumatoide/terapia , Terapia Biológica , Inibidores de Proteínas Quinases/uso terapêutico , Animais , Anticorpos Monoclonais , Antígenos de Diferenciação/imunologia , Artrite Reumatoide/genética , Artrite Reumatoide/imunologia , Terapia Biológica/tendências , Comunicação Celular/efeitos dos fármacos , Comunicação Celular/imunologia , Citocinas/imunologia , Humanos , Depleção Linfocítica , Interferência de RNA , RNA Interferente Pequeno/genética , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/imunologiaRESUMO
Articular adipose tissue is a ubiquitous component of human joints, but its local functions are largely unknown. Because recent studies revealed several links between adipose tissue, adipocytokines, and arthritis, we investigated the expression of the adipocytokine adiponectin and its functional role in articular adipose tissue and synovium of patients with different arthritides. In contrast to its protective role in endocrinological and vascular diseases, adiponectin was found to be involved in key pathways of inflammation and matrix degradation in the human joint. The effects of adiponectin in human synovial fibroblasts appear to be highly selective by inducing only two of the main mediators of rheumatoid arthritis pathophysiology, IL-6 and matrix metalloproteinase-1, via the p38 MAPK pathway. Owing to the observation that these effects could be inhibited by different TNF-alpha inhibitors, adipocytokines such as adiponectin may also be key targets for therapeutic strategies in inflammatory joint diseases. In summary, articular adipose tissue and adipocytokines cannot be regarded as innocent bystanders any more in chronic inflammatory diseases such as arthritis.
Assuntos
Adiponectina/metabolismo , Artrite/metabolismo , Adalimumab , Adiponectina/genética , Tecido Adiposo/irrigação sanguínea , Tecido Adiposo/metabolismo , Anticorpos Monoclonais/farmacologia , Anticorpos Monoclonais Humanizados , Artrite/patologia , Células Cultivadas , Fibroblastos , Regulação da Expressão Gênica/genética , Humanos , Interleucina-6/metabolismo , Metaloproteinases da Matriz/metabolismo , Ligação Proteica , RNA Mensageiro/genética , Receptores de Adiponectina , Receptores de Superfície Celular/genética , Transdução de Sinais/efeitos dos fármacos , Membrana Sinovial/metabolismo , Fator de Necrose Tumoral alfa/antagonistas & inibidoresRESUMO
PURPOSE: To evaluate intravenously administered ultrasmall superparamagnetic iron oxide (USPIO) as a marker of macrophage activity in an experimental rabbit model of antigen-induced arthritis. MATERIALS AND METHODS: Unilateral arthritis was induced by means of intraarticular injection of methylated bovine serum albumin in 10 knees of 10 rabbits that had been presensitized to the same antigen. The contralateral knees in these rabbits, as well as six knees in three other rabbits, served as controls. After onset of arthritis, all knees were imaged prior to and 24 hours after administration of USPIO. The magnetic resonance (MR) imaging protocol included T1-weighted spin-echo, T2-weighted fast spin-echo, T2*-weighted gradient-echo, and short inversion time inversion-recovery sequences. Images were analyzed quantitatively and qualitatively with regard to signal characteristics and pattern. MR findings were correlated with histopathologic findings. Wilcoxon signed rank test was used to compare results of signal-to-noise ratio calculations before and after USPIO administration. RESULTS: All knees with intraarticular injection of antigen suspension developed unilateral arthritis, whereas no signs of arthritis occurred in the control knees. On USPIO-enhanced images obtained 24 hours after contrast agent administration, significant T1 (P =.03) and more predominantly T2* (P =.02) and T2 effects (P =.01) were evident in the synovium of all 10 arthritic knees, which reflected USPIO uptake by macrophages in the synovial tissue. To a lesser extent, T2* effects were present also within the joint effusion (P =.01). No significant changes in signal characteristics were detected in the 10 nonarthritic knees in the antigen-injected group or the six knees in the control group (P =.06-.91). Histologic examination confirmed uptake of iron in the macrophages of arthritic knees. Changes in MR signal characteristics within the arthritic synovium and synovial effusion were visually detectable after intravenous administration of USPIO. CONCLUSION: MR imaging at 1.5 T can depict USPIO uptake in phagocytic-active macrophages in an antigen-induced arthritis animal model.
Assuntos
Artrite Experimental/patologia , Meios de Contraste , Aumento da Imagem/métodos , Ferro , Macrófagos/patologia , Óxidos , Membrana Sinovial/patologia , Adjuvantes Imunológicos/administração & dosagem , Animais , Artrite Experimental/imunologia , Bovinos , Meios de Contraste/administração & dosagem , Dextranos , Modelos Animais de Doenças , Feminino , Óxido Ferroso-Férrico , Injeções Intra-Articulares , Injeções Intravenosas , Ferro/administração & dosagem , Imageamento por Ressonância Magnética , Nanopartículas de Magnetita , Óxidos/administração & dosagem , Fagocitose/fisiologia , Coelhos , Albumina Sérica/administração & dosagem , Albumina Sérica/imunologia , Estatísticas não Paramétricas , Líquido SinovialRESUMO
Evaluation of genes regulated differentially is essential for the development of therapeutic approaches in multifactorial diseases. To characterize gene expression profiles in multifactorial inflammatory and malignant diseases such as rheumatoid arthritis (RA) or colon adenoma (CA), RNA arbitrarily primed PCR (RAP-PCR) combined with cDNA array hybridization were performed and evaluated using an array-specific software.RNA of synovial fibroblasts from patients with RA and osteoarthritis (OA), and laser microdissected normal and colon adenoma tissue was used. RAP-PCR reactions were hybridized to cDNA array membranes. Arrays were analyzed by phosphor imaging, and the AtlasImage 2.0 software with different normalization settings. The AtlasImage 2.0 software was a useful tool to evaluate differentially expressed genes. However, software settings were needed to be optimized for every experimental approach and should be used without changes for all experiments. To compare RA vs. OA synovial fibroblasts and normal vs. CA expression patterns, global normalization using the sum method is recommended.
Assuntos
Artrite/metabolismo , Neoplasias do Colo/metabolismo , Perfilação da Expressão Gênica/métodos , Análise de Sequência com Séries de Oligonucleotídeos/métodos , Reação em Cadeia da Polimerase/métodos , Software , Artrite/genética , Artrite Reumatoide/genética , Artrite Reumatoide/metabolismo , Artrite Reumatoide/patologia , Neoplasias do Colo/genética , Fibroblastos/metabolismo , Fibroblastos/patologia , Humanos , Osteoartrite/genética , Osteoartrite/metabolismo , Osteoartrite/patologia , Membrana Sinovial/patologiaRESUMO
We reported recently that albumin is a suitable drug carrier for targeted delivery of methotrexate (MTX) to tumors. Due to pathophysiological conditions in neoplastic tissue, high amounts of albumin accumulate in tumors and are metabolized by malignant cells. MTX, covalently coupled to human serum albumin (MTX-HSA) for cancer treatment, is currently being evaluated in phase II clinical trials. Because synovium of patients with rheumatoid arthritis (RA) shares various features observed also in tumors, albumin-based drug targeting of inflamed joints might be an attractive therapeutic approach. Therefore, the pharmacokinetics of albumin and MTX in a mouse model of arthritis was examined. Additionally, uptake of albumin by synovial fibroblasts of RA patients and the efficacy of MTX and MTX-HSA in arthritic mice were studied. The results show that when compared with MTX, significantly higher amounts of albumin accumulate in inflamed paws, and significantly lower amounts of albumin are found in the liver and the kidneys. The protein is metabolized by human synovial fibroblasts in vitro and in vivo. MTX-HSA was significantly more effective in suppression of the onset of arthritis in mice than was MTX. In conclusion, albumin appears to be a suitable drug carrier in RA, most likely due to effects on synovial fibroblasts, which might increase therapeutic efficacy and reduce side effects of MTX.
Assuntos
Artrite Reumatoide/tratamento farmacológico , Sistemas de Liberação de Medicamentos/métodos , Metotrexato/administração & dosagem , Ácido Pentético/análogos & derivados , Albumina Sérica/administração & dosagem , Albuminas/farmacocinética , Animais , Artrite Experimental/tratamento farmacológico , Artrite Experimental/metabolismo , Artrite Experimental/patologia , Artrite Reumatoide/metabolismo , Artrite Reumatoide/patologia , Células Cultivadas , Portadores de Fármacos/administração & dosagem , Portadores de Fármacos/farmacocinética , Fibroblastos/metabolismo , Fibroblastos/transplante , Humanos , Lasers , Masculino , Metotrexato/farmacocinética , Camundongos , Camundongos Endogâmicos DBA , Camundongos SCID , Microscopia Confocal , Microscopia de Fluorescência , Óptica e Fotônica , Ácido Pentético/farmacocinética , Albumina Sérica/farmacocinética , Membrana Sinovial/citologia , Membrana Sinovial/metabolismo , Membrana Sinovial/transplanteRESUMO
The aim of this study was to explore the molecular profile of proliferating rheumatoid arthritis synovial fibroblasts (RA-SF). Total RNA was extracted from two cultures of RA-SF (low-density [LD] proliferating cells and high-density [HD] nonproliferating cells) and suppression subtractive hybridization was performed to compare differential gene expression of these two cultures. Subtracted cDNA was subcloned, and nucleotide sequences were analyzed to identify each clone. Differential expression of distinct clones was confirmed by semiquantitative RT-PCR. The expression of certain genes in synovial tissues was examined by in situ hybridization. In both LD and HD cells, 44 clones were upregulated. Of the 88 total clones, 46 were identical to sequences that have previously been characterized. Twenty-nine clones were identical to cDNAs that have been identified, but with unknown functions so far, and 13 clones did not show any significant homology to sequences in GenBank (NCBI). Differential expression of distinct clones was confirmed by RT-PCR. In situ hybridization showed that certain genes, such as S100A4, NFAT5, unr and Fbx3, were also expressed predominantly in synovial tissues from patients with RA but not from normal individuals. The expression of distinct genes in proliferating RA-SF could also be found in RA synovium, suggesting that these molecules are involved in synovial activation in RA. Most importantly, the data indicate that the expression of certain genes in RA-SF depends on the stage of proliferation; therefore, the stage needs to be considered in any analysis of differential gene expression in SF.
Assuntos
Artrite Reumatoide/genética , Fibroblastos/metabolismo , Regulação da Expressão Gênica , Membrana Sinovial/metabolismo , Fatores de Transcrição/genética , Artrite Reumatoide/metabolismo , Artrite Reumatoide/patologia , Divisão Celular , Células Cultivadas , Células Clonais , DNA Complementar/genética , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Fibroblastos/patologia , Humanos , Hibridização In Situ , Fatores de Transcrição NFATC , RNA Mensageiro/genética , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Proteína A4 de Ligação a Cálcio da Família S100 , Proteínas S100/genética , Proteínas S100/metabolismo , Membrana Sinovial/patologia , Fatores de Transcrição/metabolismoRESUMO
Synovial fibroblasts from rheumatoid arthritis patients express elevated levels of the transcription factor Egr-1. The metabolic consequences of Egr-1 overexpression in fibroblasts are not known in detail. Therefore we searched for gene products that are differentially expressed in Egr-1(high) versus Egr-1(low) fibroblasts. Immortalized synovial fibroblasts were transfected with two different Egr-1 expression vectors. Expression of recombinant Egr-1 was confirmed by RT-PCR and immunoblots. Random arbitrarily primed PCR revealed that Egr-1 induces enhanced transcription levels of the alpha1 chain of type I collagen. Increased expression of the alpha2 (I) chain could also be observed. We found enhanced levels of type I collagen propeptide in supernatants and stronger signals of alpha2 (I) protein in extracts of the Egr-1(high) expressing clone versus controls. Additionally, Egr-1 was transiently expressed in fibrosarcoma cells. These cells showed a pronounced elevation of type I collagen (alpha1) transcripts as well. Moreover, we could demonstrate that Egr-1 induces transcription of other genes including type II collagen (alpha1) and plateled-derived growth factor beta1. These data suggest that upregulation of Egr-1 might contribute tofibrosis observed in rheumatoid arthritis synovium by activation of genes encoding the alpha1 and alpha2 chains of type I collagen.