title: S100A8/A9 as a biomarker for synovial inflammation and joint damage in patients with rheumatoid arthritis.
abstract: S100A8 and S100A9 are major leukocyte proteins, known as damage-associated molecular patterns, found at high concentrations in the synovial fluid of patients with rheumatoid arthritis (RA). A heterodimeric complex of S100A8/A9 is secreted by activated leukocytes and binds to Toll-like receptor 4, which mediates downstream signaling and promotes inflammation and autoimmunity. Serum and synovial fluid levels of S100A8/A9 are markedly higher in patients with RA than in patients with osteoarthritis or miscellaneous inflammatory arthritis. Serum levels of S100A8/A9 are significantly correlated with clinical and laboratory markers of inflammation, such as C-reactive protein, erythrocyte sedimentation rate, rheumatoid factor, and the Disease Activity Score for 28 joints. Significant correlations have also been found between S100A8/A9 and radiographic and clinical assessments of joint damage, such as hand radiographs and the Rheumatoid Arthritis Articular Damage score. In addition, among known inflammatory markers, S100A8/A9 has the strongest correlation with total sum scores of ultrasonography assessment. Furthermore, baseline levels of S100A8/A9 are independently associated with progression of joint destruction in longitudinal studies and are responsive to change during conventional and biologic treatments. These findings suggest S100A8/A9 to be a valuable diagnostic and prognostic biomarker for RA.
authors.affiliation: Division of Rheumatology, Department of Internal Medicine, The Catholic University of Korea College of Medicine, Seoul, Korea. ; Division of Rheumatology, Department of Internal Medicine, Incheon St. Mary's Hospital, The Catholic University of Korea College of Medicine, Incheon, Korea.
authors.forename: Kwi Young
authors.initials: KY
authors.lastname: Kang
authors.affiliation: Department of Convergent Research Consortium for Immunologic Disease, Seoul St. Mary's Hospital, The Catholic University of Korea College of Medicine, Seoul, Korea. ; Business Development, Genexine Inc., Seongnam, Korea.
authors.forename: Jung-Won
authors.initials: JW
authors.lastname: Woo
authors.affiliation: Division of Rheumatology, Department of Internal Medicine, The Catholic University of Korea College of Medicine, Seoul, Korea. ; Department of Convergent Research Consortium for Immunologic Disease, Seoul St. Mary's Hospital, The Catholic University of Korea College of Medicine, Seoul, Korea.
authors.forename: Sung-Hwan
authors.initials: SH
authors.lastname: Park
mesh_terms: D001172:Arthritis, Rheumatoid / Q000097:blood* / Q000000981:diagnostic imaging / Q000473:pathology; D001175:Arthrography; D015415:Biomarkers / Q000097:blood; D040501:Calgranulin A / Q000097:blood*; D040502:Calgranulin B / Q000097:blood*; D006801:Humans; D007596:Joints / Q000473:pathology; D013582:Synovial Fluid / Q000378:metabolism
chemical_list: D015415:Biomarkers; D040501:Calgranulin A; D040502:Calgranulin B
keywords: Arthritis, rheumatoid; Biological markers; S100A8; S100A9