Abstract
IntroductionOsteoarthritis (OA) is a whole joint disease, and characterized by progressive degradation of articular cartilage, synovial hyperplasia, bone remodeling and angiogenesis in various joint tissues. Exosomes are a type of microvesicles (MVs) that may play a role in tissue-tissue and cell-cell communication in homeostasis and diseases. We hypothesized that exosomes function in a novel regulatory network that contributes to OA pathogenesis and examined the function of exosomes in communication among joint tissue cells.MethodsHuman synovial fibroblasts (SFB) and articular chondrocytes were obtained from normal knee joints. Exosomes isolated from conditioned medium of SFB were analyzed for size, numbers, markers and function. Normal articular chondrocytes were treated with exosomes from SFB, and Interleukin-1β (IL-1β) stimulated SFB. OA-related genes expression was quantified using real-time PCR. To analyze exosome effects on cartilage tissue, we performed glycosaminoglycan release assay. Angiogenic activity of these exosomes was tested in migration and tube formation assays. Cytokines and miRNAs in exosomes were analyzed by Bio-Plex multiplex assay and NanoString analysis.ResultsExosomes from IL-1β stimulated SFB significantly up-regulated MMP-13 and ADAMTS-5 expression in articular chondrocytes, and down-regulated COL2A1 and ACAN compared with SFB derived exosomes. Migration and tube formation activity were significantly higher in human umbilical vein endothelial cells (HUVECs) treated with the exosomes from IL-1β stimulated SFB, which also induced significantly more proteoglycan release from cartilage explants. Inflammatory cytokines, IL-6, MMP-3 and VEGF in exosomes were only detectable at low level. IL-1β, TNFα MMP-9 and MMP-13 were not detectable in exosomes. NanoString analysis showed that levels of 50 miRNAs were differentially expressed in exosomes from IL-1β stimulated SFB compared to non-stimulated SFB.ConclusionsExosomes from IL-1β stimulated SFB induce OA-like changes both in vitro and in ex vivo models. Exosomes represent a novel mechanism by which pathogenic signals are communicated among different cell types in OA-affected joints.
Highlights
Osteoarthritis (OA) is a whole joint disease, and characterized by progressive degradation of articular cartilage, synovial hyperplasia, bone remodeling and angiogenesis in various joint tissues
In response to IL-1β stimulation, the expression of matrix metalloproteinase (MMP)-3, MMP-13, IL-1β, IL-6, and vascular endothelial growth factor (VEGF) were significantly increased compared with non-stimulated synovial fibroblasts (SFB) (Figure 1)
Exosomes in IL-1β-stimulated SFB-conditioned medium To examine whether the secretion of exosomes from SFB is influenced by the IL-1β treatment, we analyzed the size and the number of isolated nanoparticles including exosomes from conditioned medium by ultracentrifugation
Summary
Osteoarthritis (OA) is a whole joint disease, and characterized by progressive degradation of articular cartilage, synovial hyperplasia, bone remodeling and angiogenesis in various joint tissues. OA risk factors include aging, acute or chronic mechanical stress, joint trauma, and metabolic disorders [1,2]. These factors impair the homeostatic balance between cartilage extracellular matrix (ECM) degradation and repair. Joint inflammation at varying intensity is present and contributes to the chronic joint tissue remodeling process and to pain, the main subjective symptom in OA patients [2,3,4,5,6]. The homeostatic balance of all joint tissues is regulated by intracellular molecules such as kinase cascades, autophagy, and transcription factors, epigenetic mechanisms, including miRNAs and by extracellular stimuli including cytokines, hormones and mechanical stress [7,8]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
