CCN4 induces IL-6 production through αvβ5 receptor, PI3K, Akt, and NF-κB singling pathway in human synovial fibroblasts
Journal
Arthritis Research and Therapy
Journal Volume
15
Journal Issue
1
Date Issued
2013
Author(s)
Abstract
Introduction: Osteoarthritis (OA) is the most common degenerative joint disease that is involved in the degradation of articular cartilage. The exact etiology of OA is not completely understood. CCN4 is related to up-regulation in the cartilage of patients with osteoarthritis. Previous studies have shown that CCN4 might be associated with the pathogenesis of OA, but the exact signaling pathways in CCN4-mediated IL-6 expression in synovial fibroblasts (SF) are largely unknown. Therefore, we explored the intracellular signaling pathway involved in CCN4-induced IL-6 production in human synovial fibroblast cells.Methods: CCN4-induced IL-6 production was assessed with quantitative real-time qPCR and ELISA. The mechanisms of action of CCN4 in different signaling pathways were studied by using Western blotting. Neutralizing antibodies of integrin were used to block the integrin signaling pathway. Luciferase assays were used to study IL-6 and NF-κB promoter activity. Immunocytochemistry was used to examine the translocation activity of p65.Results: Osteoarthritis synovial fibroblasts (OASFs) showed significant expression of CCN4 and the expression was higher than in normal SFs. OASF stimulation with CCN4 induced concentration- and time-dependent increases in IL-6 production. Pretreatment of OASFs with αvβ5 but not α5β1 and αvβ3 integrin antibodies reduced CCN4-induced IL-6 production. CCN4-mediated IL-6 production was attenuated by PI3K inhibitor (LY294002 and Wortmannin), Akt inhibitor (Akti), and NF-κB inhibitor (PDTC and TPCK). Stimulation of cells with CCN4 also increased PI3K, Akt, and NF-κB activation.Conclusions: Our results suggest that CCN4 activates αvβ5 integrin, PI3K, Akt, and NF-κB pathways, leading to up-regulation of IL-6 production. According to our results, CCN4 may be an appropriate target for drug intervention in OA in the future. ? 2013 Hou et al.; licensee BioMed Central Ltd.
SDGs
Other Subjects
alphaVbeta5 integrin; immunoglobulin enhancer binding protein; interleukin 6; neutralizing antibody; phosphatidylinositol 3 kinase; protein kinase B; synaptotagmin I; unclassified drug; wnt inducible signaling pathway protein 1; Wnt protein; alphaVbeta5 integrin; CCN protein; IL6 protein, human; immunoglobulin enhancer binding protein; interleukin 6; oncoprotein; phosphatidylinositol 3 kinase; protein kinase B; vitronectin receptor; WISP1 protein, human; article; controlled study; cytokine production; enzyme linked immunosorbent assay; fibroblast; human; human cell; immunocytochemistry; intracellular signaling; osteoarthritis; real time polymerase chain reaction; upregulation; Western blotting; biosynthesis; cell culture; genetic transfection; immunohistochemistry; immunology; metabolism; signal transduction; synovium; Blotting, Western; CCN Intercellular Signaling Proteins; Cells, Cultured; Fibroblasts; Humans; Immunohistochemistry; Interleukin-6; NF-kappa B; Osteoarthritis; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-akt; Real-Time Polymerase Chain Reaction; Receptors, Vitronectin; Signal Transduction; Synovial Membrane; Transfection
Type
journal article