Unknown,Transcriptomics,Genomics,Proteomics

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Regulation of synovial DKK1 expression by local glucocorticoid metabolism in inflammatory arthritis

ABSTRACT: Inflammatory arthritis is associated with bone loss and fractures due to abnormal bone remodelling. Bone remodelling is 'uncoupled' with bone resorption increased and bone formation suppressed. These changes resemble those seen in patients treated with therapeutic glucocorticoids, and in both of these situations, altered wnt signalling is implicated. Recent studies have highlighted the importance of the synovial fibroblast in mediating abnormal bone remodelling during inflammation. The wnt antagonist dickkopf-1 (DKK1) is secreted by synovial fibroblasts in response to inflammation, and this protein has been proposed to be a master regulator of bone remodelling in inflammatory arthritis. Here we show that DKK1 expression by primary human synovial fibroblasts is more potently regulated by glucocorticoids than pro-inflammatory cytokines. Glucocorticoids, but not TNF-alpha, regulated expression of multiple wnt agonists and antagonists in favour of inhibition of wnt signalling. In vitro TNF-alpha and IL1-beta indirectly regulate DKK1 production through increased expression of the glucocorticoid activating enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). These results demonstrate that the links between synovial inflammation, altered wnt signalling and bone remodelling may not be direct but are dependent on local activation of endogenous glucocorticoids. Human fibroblast-like synoviocytes isolated from patients with rheumatoid arthritis treated with either vehicle, TNF or dexamethasone (dex). Gene arrays for control, TNF and dexamethasone treatments were performed on three separate synovial fibroblast cell lines isolated from three rheumatoid arthritis patients. All fold changes displayed are the combined results of the three separate fibroblast lines.

ORGANISM(S): Homo sapiens

SUBMITTER: Rowan Hardy

PROVIDER: E-GEOD-37520 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Synovial DKK1 expression is regulated by local glucocorticoid metabolism in inflammatory arthritis.

Hardy Rowan R Juarez Maria M Naylor Amy A Tu Jinwen J Rabbitt Elizabeth H EH Filer Andrew A Stewart Paul M PM Buckley Christopher D CD Raza Karim K Cooper Mark S MS

Arthritis research & therapy 20121018 5

<h4>Introduction</h4>Inflammatory arthritis is associated with increased bone resorption and suppressed bone formation. The Wnt antagonist dickkopf-1 (DKK1) is secreted by synovial fibroblasts in response to inflammation and this protein has been proposed to be a master regulator of bone remodelling in inflammatory arthritis. Local glucocorticoid production is also significantly increased during joint inflammation. Therefore, we investigated how locally derived glucocorticoids and inflammatory c ...[more]

PMID: 23079210

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Project description:Synovial fibroblasts in persistent inflammatory arthritis have been suggested to have parallels with cancer growth and wound healing, both of which involve a stereotypical serum response program. We tested the hypothesis that a serum response program can be used to classify diseased tissues, and investigated the serum response program in fibroblasts from multiple anatomical sites and two diseases. To test our hypothesis we utilized a bioinformatics approach to explore a publicly available microarray dataset including RA, OA and normal synovial tissue, then extended those findings in a new microarray dataset representing matched synovial, bone marrow and skin fibroblasts cultured from RA and OA patients undergoing arthroplasty. The classical fibroblast serum response program discretely classified RA, OA and normal synovial tissues. Analysis of low and high serum treated fibroblast microarray data revealed a hierarchy of control, with anatomical site the most powerful classifier followed by response to serum and then disease. In contrast to skin and bone marrow fibroblasts, exposure of synovial fibroblasts to serum led to convergence of RA and OA expression profiles. Pathway analysis revealed three inter-linked gene networks characterising OA synovial fibroblasts: Cell remodelling through insulin-like growth factors, differentiation and angiogenesis through ?3 integrin, and regulation of apoptosis through CD44. We have demonstrated that Fibroblast serum response signatures define disease at the tissue level, and that an OA specific, serum dependent repression of genes involved in cell adhesion, extracellular matrix remodelling and apoptosis is a critical discriminator between cultured OA and RA synovial fibroblasts. Fibroblasts were isolated from synovium, bone marrow and skin tissue samples taken at the time of knee or hip replacement surgery from 12 rheumatoid arthritis patients meeting the 1987 ACR criteria and 6 osteoarthritis patients diagnosed on the basis of characteristic x-ray findings and the absence of features suggestive of inflammatory arthritis. Only one hip sample was present in either disease group. Fibroblasts were maintained in fibroblast medium (consisting of 81.3% RPMI 1640, 10% FCS, 0.81x MEM non-essential amino acids, 0.81mM sodium orthopyruvate, 1.62mM glutamine, 810U/ml penicillin and 81?g/ml streptomycin) at 37°C in a humidified 5% CO2 atmosphere.

Dataset Information

Regulation of synovial DKK1 expression by local glucocorticoid metabolism in inflammatory arthritis

Publications

Synovial DKK1 expression is regulated by local glucocorticoid metabolism in inflammatory arthritis.

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