{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,24]],"date-time":"2026-06-24T05:46:30Z","timestamp":1782279990962,"version":"3.54.5"},"reference-count":37,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,6,24]],"date-time":"2026-06-24T00:00:00Z","timestamp":1782259200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Pediatr."],"abstract":"<jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>\n                      The innate immune system is increasingly recognised as a key driver in the pathogenesis of juvenile idiopathic arthritis (JIA). Extracellular vesicles (EVs) have emerged as important mediators of inflammation, potentially reflecting cellular activation and disease processes\n                      <jats:italic>in vivo<\/jats:italic>\n                      . The aim of this exploratory pilot study was to investigate the presence of neutrophil- and platelet-derived EVs in the plasma and synovial fluid of children with JIA and compare these with plasma levels in healthy controls.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Seven children with active, untreated JIA and ten healthy controls were included. Citrate plasma and synovial fluid were analysed for neutrophil- and platelet-derived EVs using flow cytometry. Disease activity was assessed using the Juvenile Arthritis Disease Activity Score (JADAS27) and functional impairment via the Childhood Health Assessment Questionnaire (CHAQ). Non-parametric tests were used in analyses.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Neutrophil- and platelet-associated EVs were detectable not only in plasma but also in synovial fluid in all children with JIA. Plasma levels of CD41+ EVs and MPO+ EVs were significantly higher in the JIA group compared with controls. Activated platelet EVs (CD41+ and CD41\u2009+\u2009CD62P) were detected predominantly in plasma and only at low levels in synovial fluid. MPO+ and H3Cit+ EVs were present in both compartments, indicating neutrophil activation and NET-related components. No correlations between EV levels and clinical or laboratory variables were found.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>This exploratory pilot study is the first to assess platelet- and neutrophil\/NET-associated EV phenotypes in both plasma and synovial fluid in children with JIA. The results indicate systemic platelet activation and NET-related activity in both circulation and the inflamed joint compartment.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fped.2026.1833576","type":"journal-article","created":{"date-parts":[[2026,6,24]],"date-time":"2026-06-24T04:47:12Z","timestamp":1782276432000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Exploratory analysis of neutrophil extracellular traps in synovial fluid and plasma from children with juvenile idiopathic arthritis"],"prefix":"10.3389","volume":"14","author":[{"given":"Lillemor","family":"Berntson","sequence":"first","affiliation":[{"name":"Department of Women\u2019s and Children\u2019s Health, Uppsala University","place":["Uppsala, Sweden"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Caroline","family":"Sandstr\u00f6m","sequence":"additional","affiliation":[{"name":"Department of Women\u2019s and Children\u2019s Health, Uppsala University","place":["Uppsala, Sweden"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Andreas","family":"Elfving","sequence":"additional","affiliation":[{"name":"Department of Women\u2019s and Children\u2019s Health, Uppsala University","place":["Uppsala, Sweden"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fariborz","family":"Mobarrez","sequence":"additional","affiliation":[{"name":"Department of Medical Sciences, Clinical Chemistry, Uppsala University","place":["Uppsala, Sweden"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,6,24]]},"reference":[{"key":"B1","first-page":"390","article-title":"International league of associations for rheumatology classification of juvenile idiopathic arthritis: second revision, Edmonton, 2001","volume":"31","author":"Petty","year":"2004","journal-title":"J 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