{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T22:59:18Z","timestamp":1785452358443,"version":"3.56.0"},"reference-count":16,"publisher":"Wiley","issue":"7","license":[{"start":{"date-parts":[[2026,6,26]],"date-time":"2026-06-26T00:00:00Z","timestamp":1782432000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"},{"start":{"date-parts":[[2026,6,26]],"date-time":"2026-06-26T00:00:00Z","timestamp":1782432000000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"funder":[{"DOI":"10.13039\/501100001691","name":"Japan Society for the Promotion of Science","doi-asserted-by":"publisher","award":["23K07890"],"award-info":[{"award-number":["23K07890"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["acrjournals.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["ACR Open Rheumatology"],"published-print":{"date-parts":[[2026,7]]},"abstract":"<jats:sec>\n                    <jats:title>Objective<\/jats:title>\n                    <jats:p>Late\u2010onset rheumatoid arthritis (LORA) and polymyalgia rheumatica (PMR) can be difficult to distinguish, particularly in anti\u2013citrullinated protein antibody (ACPA)\u2010negative patients. We aimed to characterize synovial fluid immune cell profiles in ACPA\u2010positive LORA, ACPA\u2010negative LORA, and PMR, and to explore biologically informed patient stratification using an unbiased approach.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Synovial fluid was aspirated from inflamed periarticular synovial structures of the shoulder, including the subacromial and subdeltoid bursae and the tendon sheath of the long head of the biceps, in 21 patients with ACPA\u2010positive LORA (n\u00a0=\u00a05), ACPA\u2010negative LORA (n\u00a0=\u00a08), or PMR (n\u00a0=\u00a08). Immune cell composition was analyzed by mass cytometry. Principal component analysis and hierarchical clustering were performed to stratify patients.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>ACPA\u2010positive LORA demonstrated neutrophil predominance compared with PMR. In contrast, PMR demonstrated a neutrophil\u2010poor profile characterized by higher proportions of T cells and natural killer cells. ACPA\u2010negative LORA showed substantial heterogeneity, with individual patients displaying either neutrophil\u2010rich or neutrophil\u2010poor patterns. Unsupervised clustering of mass cytometry data segregated ACPA\u2010positive LORA and PMR into distinct clusters, whereas ACPA\u2010negative LORA cases were distributed across both clusters.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>This exploratory study suggests that late\u2010onset inflammatory arthritis comprises at least two distinct synovial inflammatory phenotypes that may not fully correspond to current clinical diagnoses. ACPA\u2010negative LORA appears to represent a heterogeneous condition encompassing these distinct states of inflammation. Synovial fluid immunophenotyping may complement conventional classification and support biologically informed therapeutic stratification.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1002\/acr2.90086","type":"journal-article","created":{"date-parts":[[2026,6,27]],"date-time":"2026-06-27T02:49:38Z","timestamp":1782528578000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Synovial Fluid Cell Profiling Identifies Distinct Inflammatory Phenotypes in Late\u2010Onset Rheumatoid Arthritis and Polymyalgia Rheumatica"],"prefix":"10.1002","volume":"8","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8466-110X","authenticated-orcid":false,"given":"Shigeru","family":"Tanaka","sequence":"first","affiliation":[{"name":"Department of Allergy and Clinical Immunology, Graduate School of Medicine Chiba University  Chiba 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Allergy and Clinical Immunology, Graduate School of Medicine Chiba University  Chiba Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuki","family":"Hayashi","sequence":"additional","affiliation":[{"name":"Department of Allergy and Clinical Immunology, Graduate School of Medicine Chiba University  Chiba Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tomoaki","family":"Ida","sequence":"additional","affiliation":[{"name":"Department of Allergy and Clinical Immunology, Graduate School of Medicine Chiba University  Chiba Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuhi","family":"Yoshida","sequence":"additional","affiliation":[{"name":"Department of Rheumatology Dokkyo Medical University  Mibu Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Soichiro","family":"Kubota","sequence":"additional","affiliation":[{"name":"Department of Rheumatology University of Yamanashi Hospital  Yamanashi 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