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bioRxiv · 10.1101/2023.11.30.569010

The immune landscape of the inflamed joint defined by spectral flow cytometry

Attrill, M. H.·Shinko, D.·Alexiou, V.·Kartawinata, M.·Wedderburn, L. R.·CHARMS study,·JIAP study,·Pesenacker, A. M.
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Abstract

Cellular phenotype and function are altered in different microenvironments. For targeted therapies it is important to understand site-specific cellular adaptations. Juvenile Idiopathic Arthritis (JIA) is characterised by joint inflammation, with frequent inadequate treatment responses. To comprehensively assess the inflammatory immune landscape, we designed a 37-parameter spectral flow cytometry panel delineating mononuclear cells from JIA synovial fluid (SF), compared to JIA and healthy control blood. Synovial monocytes and NK cells lack the Fc-receptor CD16, suggesting antibody-mediated targeting may be ineffective. B cells and DCs, both in small frequencies in SF, undergo maturation with high 4-1BB, CD71, CD39 expression, supporting T cell activation. SF effector and regulatory T cells were highly active with newly described co-receptor combinations that may alter function, and suggestion of metabolic reprogramming via CD71, TNFR2 and PD-1. Most SF effector phenotypes, as well as an identified CD4-Foxp3+ T cell population, were restricted to the inflamed joint, yet specific SF-predominant Treg (CD4+Foxp3+) subpopulations were increased in blood of active but not inactive JIA, suggesting possible recirculation and loss of immunoregulation at distal sites. This first comprehensive dataset of the site-specific inflammatory landscape at protein level will inform functional studies and the development of targeted therapeutics to restore immunoregulatory balance and achieve remission in JIA. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=146 SRC="FIGDIR/small/569010v1_ufig1.gif" ALT="Figure 1"> View larger version (44K): org.highwire.dtl.DTLVardef@66c213org.highwire.dtl.DTLVardef@4f99b5org.highwire.dtl.DTLVardef@1f475bborg.highwire.dtl.DTLVardef@5d533f_HPS_FORMAT_FIGEXP M_FIG C_FIG

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Attrill, M. H., Shinko, D., Alexiou, V., Kartawinata, M., Wedderburn, L. R., CHARMS study,, JIAP study,, Pesenacker, A. M.. 2023-12-04. The immune landscape of the inflamed joint defined by spectral flow cytometry. https://doi.org/10.1101/2023.11.30.569010

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