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Updated: Jul 19, 2026

A Pre-Clinical Model of Synovitis Using Ex vivo Human Synovial Tissue with Preserved Function and Architecture
Published on: March 20, 2026
Distinct expression pattern of IFN-alpha and TNF-alpha in juvenile idiopathic arthritis synovial tissue
M Gattorno1, L Chicha, A Gregorio
1Second Division of Pediatrics, G. Gaslini Institute and University of Genoa, Largo G. Gaslini 5, 16147, Genoa, Italy. marcogattorno@ospedale-gaslini.ge.it
Objectives:
Recent laboratory and clinical data suggest that two prototype autoimmune diseases, systemic lupus erythematosus and rheumatoid arthritis are mainly driven by distinct cytokines, interferon (IFN)-alpha and tumour necrosis factor (TNF)-alpha, respectively. We here investigated the presence and characteristics of natural type I IFN-producing cells (IPCs), as well as IFN-alpha and TNF-alpha expression at sites of inflammation in juvenile idiopathic arthritis (JIA).
Methods:
Peripheral blood (PB) and synovial fluid (SF) mononuclear cells (MNCs) (n = 25 each) from JIA patients with active disease were studied. IPCs were identified as BCDA-2(+)CD123(+)HLA-DR(+)CD45RA(+) cells, and dendritic cells (DCs) as CD11c(+)CD14(-/low)lin(-) cells by flow cytometry. IPCs and DCs were analysed for Toll-like receptor-7 and -9 mRNA expression by real-time polymerase chain reaction. IFN-alpha was measured by enzyme-linked immunosorbent assay in serum, SF and in supernatants of influenza virus-infected, cultured IPCs. Synovial tissues of n = 6 additional JIA patients were analysed by immunohistochemistry using mAbs against CD123, IFN-alpha, TNF-alpha, CD3, CD19 and CD138.
Results:
IPCs were enriched in SF MNCs compared with PB MNCs in all JIA patients. Influenza-induced, but no spontaneous IFN-alpha release was detected from SF IPCs, and serum and SF IFN-alpha levels were not elevated. Nonetheless, in synovial tissue IFN-alpha producing cells accumulated at inflammatory lymph-follicular-like structures, while TNF-alpha producing cells were mostly found at the lining and sublining layers.
Conclusions:
These data suggest that besides TNF-alpha-expressing cells, IFN-alpha-producing IPCs are involved in initiation, maintenance or regulation of the inflammatory response in JIA.
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