Abstract
To analyze the role of Toll-like receptors (TLR) in the pathogenesis of rheumatoid arthritis, we have assessed the effects of stimulation of cultured synovial fibroblasts by the TLR-2 ligand bacterial peptidoglycan. By using high density oligonucleotide microarray analysis we identified 74 genes that were up-regulated >2.5-fold. Fourteen CC and CXC chemokine genes were among the genes with the highest up-regulation. Quantitative real-time PCR analysis confirmed up-regulation of granulocyte chemotactic protein (GCP)-2, RANTES, monocyte chemoattractant protein (MCP)-2, IL-8, growth-related oncogene-2, and to a lesser extent, macrophage-inflammatory protein 1alpha, MCP-1, EXODUS, and CXCL-16. GCP-2, RANTES, and MCP-2 were detected in culture supernatants of synovial fibroblasts stimulated with peptidoglycan. Chemokine secretion induced by stimulation of rheumatoid arthritis synovial fibroblasts via TLR-2 was functionally relevant as demonstrated by chemotaxis assays. GCP-2 and MCP-2 expression, which have not been reported previously in rheumatoid arthritis, was demonstrated in synovial tissue sections of patients diagnosed with rheumatoid arthritis but not in those with osteoarthritis. Correspondingly, synovial fluid levels were significantly higher in patients diagnosed with rheumatoid arthritis as compared with osteoarthritis. Thus, we present evidence for an induction of chemokine secretion by activation of synovial fibroblasts via TLR-2, possibly contributing to the formation of inflammatory infiltrates characteristically found in rheumatoid arthritis joints.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adult
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Aged
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Arthritis, Rheumatoid / immunology*
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Arthritis, Rheumatoid / metabolism
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Arthritis, Rheumatoid / microbiology
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Cells, Cultured
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Chemokine CCL5 / biosynthesis
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Chemokine CCL5 / metabolism
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Chemokine CCL8
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Chemokine CXCL6
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Chemokines / metabolism*
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Chemokines, CXC / biosynthesis
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Chemokines, CXC / metabolism
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Chemotaxis, Leukocyte / immunology
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Fibroblasts / immunology*
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Fibroblasts / metabolism*
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Fibroblasts / pathology
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Gene Expression Profiling
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Humans
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Ligands
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Membrane Glycoproteins / antagonists & inhibitors
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Membrane Glycoproteins / metabolism
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Membrane Glycoproteins / physiology*
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Middle Aged
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Monocyte Chemoattractant Proteins / biosynthesis
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Monocyte Chemoattractant Proteins / metabolism
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NF-kappa B / antagonists & inhibitors
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NF-kappa B / metabolism
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Oligonucleotide Array Sequence Analysis
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Osteoarthritis / immunology
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Osteoarthritis / metabolism
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Peptidoglycan / pharmacology
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Receptors, Cell Surface / antagonists & inhibitors
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Receptors, Cell Surface / metabolism
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Receptors, Cell Surface / physiology*
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Synovial Fluid / immunology
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Synovial Fluid / metabolism
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Synovial Membrane / immunology*
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Synovial Membrane / metabolism*
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Synovial Membrane / pathology
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Toll-Like Receptor 2
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Toll-Like Receptors
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Up-Regulation / immunology
Substances
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CCL8 protein, human
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CXCL6 protein, human
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Chemokine CCL5
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Chemokine CCL8
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Chemokine CXCL6
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Chemokines
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Chemokines, CXC
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Ligands
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Membrane Glycoproteins
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Monocyte Chemoattractant Proteins
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NF-kappa B
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Peptidoglycan
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Receptors, Cell Surface
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TLR2 protein, human
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Toll-Like Receptor 2
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Toll-Like Receptors