Extracellular vesicles in osteoarthritis synovial fluid contain both transmembrane and intravesical TNF-α
Objective: We previously identified extracellular vesicles (EVs) as a key source of TNF-α in the plasma of both knee osteoarthritis (OA) patients and healthy individuals. Building on these findings, this study aimed to evaluate the presence of surface-bound transmembrane TNF-α (TM-TNF-α) and intrave...
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| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-06-01
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| Series: | Osteoarthritis and Cartilage Open |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2665913125000482 |
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| Summary: | Objective: We previously identified extracellular vesicles (EVs) as a key source of TNF-α in the plasma of both knee osteoarthritis (OA) patients and healthy individuals. Building on these findings, this study aimed to evaluate the presence of surface-bound transmembrane TNF-α (TM-TNF-α) and intravesical TNF-α in EVs from OA synovial fluid (SF). Methods: Using high-resolution flow cytometry, we rigorously quantified the percentages and integrated mean fluorescence intensity (iMFI) of surface-bound, intravesical, and total TNF-α forms in EVs isolated from SF of 25 knee OA patients. CZ CELLxGENE and OA joint tissue-derived single-cell and single-nuclei RNA sequencing data were used to analyze TNF gene expression. Results: TNF is expressed across multiple cell types. In OA joints it is predominantly expressed by synoviocytes, with TNF-α present in the SF EV pool. TM-TNF-α was consistently detected on SF EVs using three distinct TNF-α antibodies, although its frequency and iMFI were significantly lower than the corresponding intravesical TNF-α (Friedman test with Benjamini-Hochberg correction, FDR <0.05). The average percentages (and range) of EVs expressing TNF-α, as detected by the three anti-TNF-α antibodies, were 2.57 % (0.09–37.08 %) for TM-TNF-α+, 8.62 % (0.38–43.64 %) for intravesical TNF-α+, and 14.42 % (0.71–44.32 %) for total EV TNF-α+. Interestingly, TM-TNF-α frequencies on SF EVs were similar to those observed on various immune cell subsets in peripheral blood. Conclusions: While intravesical TNF-α may evade TNF-α inhibitors, TNF-α carried by EVs retains pathogenic potential, either by activating pro-inflammatory pathways via TM-TNF-α receptor engagement on target cells, or through the transfer of TNF-α cargo to recipient cells. |
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| ISSN: | 2665-9131 |