Direct comparison of non-osteoarthritic and osteoarthritic synovial fluid-induced intracellular chondrocyte signaling and phenotype changes
Bas Housmans, Guus van den Akker, M. Neefjes, Ufuk Tan Timur, Andy Cremers, Mandy J. Peffers, Marjolein M. J. Caron, Lodewijk W. van Rhijn, Pieter J. Emans, T.A.E.J. Boymans, Peter Z. Feczkó, P.M. van der Kraan, Tim J. M. Welting
Abstract
OBJECTIVE: Since the joint microenvironment and tissue homeostasis are highly dependent on synovial fluid, we aimed to compare the essential chondrocyte signaling signatures of non-osteoarthritic vs end-stage osteoarthritic knee synovial fluid. Moreover, we determined the phenotypic consequence of the distinct signaling patterns on articular chondrocytes. METHODS: Protein profiling of synovial fluid was performed using antibody arrays. Chondrocyte signaling and phenotypic changes induced by non-osteoarthritic and osteoarthritic synovial fluid were analyzed using a phospho-kinase array, luciferase-based transcription factor activity assays, and RT-qPCR. The origin of osteoarthritic synovial fluid signaling was evaluated by comparing the signaling responses of conditioned media from cartilage, synovium, infrapatellar fat pad and meniscus. Osteoarthritic synovial fluid induced pathway-phenotype relationships were evaluated using pharmacological inhibitors. RESULTS: K/AKT routes, and enabling of chondrocyte proliferation. CONCLUSION: K/AKT as crucial OA-associated intracellular signaling routes.