Synovial Tissue‐Guided Interleukin‐17A Inhibition for Refractory Arthritis in a Patient With Systemic Juvenile Idiopathic Arthritis
Authors' conclusion
STAT5B haploinsufficiency may contribute to an sJIA phenotype characterized by Th17/IL-17 dysregulation and an altered distribution of Th17 cells outside TLS. Integrated genetic, functional, and spatial tissue analyses may help identify therapeutic targets in refractory pediatric arthritis.
Study context
- Population
- A patient with systemic juvenile idiopathic arthritis (sJIA) carrying a novel heterozygous STAT5B loss-of-function variant (p.Gln139Ter)one patient, controls: healthy donors (n = 5) for blood, oligo/poly JIA (n = 5–6) for synovial fluid, children with oligo/poly JIA (n = 11) for synovial tissue · healthy donors (blood) 5 · oligo/poly JIA (synovial fluid) 5-6 · children with oligo/poly JIA (synovial tissue) 11
- Comparison
- Patient blood vs healthy donors; patient synovial fluid and synovial tissue vs oligo/poly JIA controls
- Outcome
- STAT5 phosphorylation in CD4+ T cells
Methodological detailscomparison with healthy donors and oligo/poly JIA controls, immunoblotting, phospho-flow cytometry, immune cell profiling, Xenium spatial transcriptomics
- Comparison with healthy donors and oligo/poly JIA controls
- Immunoblotting
- Phospho-flow cytometry
- Immune cell profiling
- Xenium spatial transcriptomics
Main finding
As reported in the abstract
Impaired in patient, z score
−11.1
Further findings
IL-17A production by synovial fluid CD4+ T cells
- Markedly increased, z score
- 34.5
FOXP3 expression in regulatory T cells
- Reduced, z score
- −2.25
Distribution of Th17 cells in synovium
- Diffuse in patient vs largely restricted to tertiary lymphoid structures (TLS) in JIA controls, z score
- 3.08
Arthritis after IL-17A inhibition
- Severe arthritis, previously refractory to IL-1 and IL-6 blockade, improved markedly
Original publication
Synovial Tissue‐Guided Interleukin‐17A Inhibition for Refractory Arthritis in a Patient With Systemic Juvenile Idiopathic Arthritis. Arthritis Rheumatol. Published 6 November 2026. doi:10.
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