{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,3]],"date-time":"2026-09-03T11:22:16Z","timestamp":1788434536100,"version":"build-2803163510"},"reference-count":37,"publisher":"BMJ","issue":"1","license":[{"start":{"date-parts":[[2026,2,20]],"date-time":"2026-02-20T00:00:00Z","timestamp":1771545600000},"content-version":"unspecified","delay-in-days":50,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"funder":[{"name":"Guangzhou Science and Technology Program Key Project","award":["SL2024A04J01618"],"award-info":[{"award-number":["SL2024A04J01618"]}]},{"name":"The Five Five Project of the Third Affiliated Hospital of Sun Yat-sen University","award":["2023ww203"],"award-info":[{"award-number":["2023ww203"]}]},{"name":"Fundamental Research Funds for the Central Universities, Sun Yat-sen University","award":["24qnpy264"],"award-info":[{"award-number":["24qnpy264"]}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"crossref","award":["82271849"],"award-info":[{"award-number":["82271849"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["RMD Open"],"accepted":{"date-parts":[[2026,1,18]]},"published-print":{"date-parts":[[2026,1]]},"abstract":"<jats:sec>\n                    <jats:title>Objective<\/jats:title>\n                    <jats:p>\n                      Anaemia is common in rheumatoid arthritis (RA), but the role of erythroid-lineage cells is unclear. We investigated the function of CD45\n                      <jats:sup>+<\/jats:sup>\n                      erythroid progenitor cells (CD45\n                      <jats:sup>+<\/jats:sup>\n                      EPCs) in RA.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>\n                      We analysed CD45\n                      <jats:sup>+<\/jats:sup>\n                      EPC frequency in patients with RA and mice with collagen-induced arthritis (CIA). Transcriptomics, functional studies and mechanistic assays (Transwell and dual-luciferase reporter assays, chromatin immunoprecipitation followed by quantitative PCR) were used. Therapeutic potential was tested in RA synovial organoids and via splenectomy\/adoptive transfer in mice with CIA.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      CD45\n                      <jats:sup>+<\/jats:sup>\n                      EPCs were expanded in RA circulation and CIA mouse spleens, correlating positively with disease activity and negatively with haemoglobin. They displayed an immunosuppressive transcriptome, enriched for transforming growth factor (TGF)-\u03b2 and chemokine signalling. RA-derived CD45\n                      <jats:sup>+<\/jats:sup>\n                      EPCs showed enhanced proliferation and TGF-\u03b2\/reactive oxygen species production. High C-C Motif Chemokine Receptor 2 (CCR2) expression made them susceptible to recruitment by macrophage-derived C-C Motif Chemokine Ligand 2 (CCL2). In RA synovial organoids, CD45\n                      <jats:sup>+<\/jats:sup>\n                      EPCs suppressed growth and inflammation via TGF-\u03b2, while organoid-conditioned media promoted their migration via CCL2. Recruited CD45\n                      <jats:sup>+<\/jats:sup>\n                      EPCs suppressed M1 and promoted M2-like macrophage polarisation. The transcription factor SPI1 was upregulated in RA CD45\n                      <jats:sup>+<\/jats:sup>\n                      EPCs, bound the\n                      <jats:italic>TGFB1<\/jats:italic>\n                      promoter and drove TGF-\u03b2 production. In vivo, splenectomy worsened CIA, whereas adoptive transfer of CD45\n                      <jats:sup>+<\/jats:sup>\n                      EPCs ameliorated arthritis.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>\n                      We identify CD45\n                      <jats:sup>+<\/jats:sup>\n                      EPCs as a novel, SPI1-driven immunosuppressive population in RA. Recruited via the CCR2-CCL2 axis, they attenuate inflammation by modulating macrophages through SPI1\/TGF-\u03b2 signalling, revealing a new immunoregulatory axis and potential therapeutic targets.\n                    <\/jats:p>\n                  <\/jats:sec>","DOI":"10.1136\/rmdopen-2025-006472","type":"journal-article","created":{"date-parts":[[2026,2,20]],"date-time":"2026-02-20T16:50:24Z","timestamp":1771606224000},"page":"e006472","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":1,"title":["Transcription factor SPI1 drives immunosuppressive CD45\n                    <sup>+<\/sup>\n                    erythroid progenitor cells to ameliorate rheumatoid arthritis"],"prefix":"10.1136","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0009-0008-9373-7349","authenticated-orcid":false,"given":"Wei-Hang","family":"Zhu","sequence":"first","affiliation":[{"name":"Department of Rheumatology and Immunology, Third Affiliated 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Immunology, Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1468-0898","authenticated-orcid":false,"given":"Yan","family":"Liu","sequence":"additional","affiliation":[{"name":"Department of Rheumatology and Immunology, Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7459-4970","authenticated-orcid":false,"given":"Yun-Feng","family":"Pan","sequence":"additional","affiliation":[{"name":"Department of Rheumatology and Immunology, Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"239","published-online":{"date-parts":[[2026,2,20]]},"reference":[{"key":"2026090304053127000_12.1.e006472.1","first-page":"591","article-title":"Global 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