title: Tartrate-resistant acid phosphatase 5b is a potential biomarker for rheumatoid arthritis: a pilot study in Han Chinese.
abstract: BACKGROUND
  Bone damage around the joints is one of the major pathophysiological mechanisms that leads to rheumatoid arthritis (RA) chronic disability. Serum tartrate-resistant acid phosphatase 5b (TRACP-5b) is secreted by osteoclasts, its activity can be used as a clinically relevant bone resorption marker. The aim of this study was to test whether the measurement of serum levels of TRACP-5b in patients with RA would correlate with measures of disease activity and with responses to therapy.
  
  
  METHODS
  Fifty-six patients were randomly assigned to receive recombinant human cytotoxic tlymphocyte-associated antigen-4 immunoglobulin (RhCTLA4-Ig), infliximab or methotrexate (MTX). The clinical and serologic indicators of RA activity were evaluated at baseline and at 24 weeks. Serum TRACP-5b was measured by Enzyme-linked Immunosorbent Assay (ELISA) at 0, 12 and 24 weeks. Hand X-rays were obtained at baseline.
  
  
  RESULTS
  At baseline, the levels of TRACP-5b correlated with the severity of X-ray damage, disease duration (r = 0.332, P = 0.012), and tender joint count (r = 0.408, P = 0.002). The 24 weeks values of TRACP-5b for RhCTLA4-Ig group and infliximab group differed significantly from the baseline values in each group (P < 0.05; P < 0.05), whereas only the value for RhCTLA4-Ig group differed significantly from the 24 weeks value for the MTX group (P < 0.01). Considering the two biologics-treated groups together, the TRACP-5b levels at 24 weeks differed significantly from the baseline values only in those patients who reached an ACR70 level (P < 0.05).
  
  
  CONCLUSIONS
  Measurement of serum TRACP-5b in RA patients reflects clinical and radiological measures of disease activity, treatment with certain biologics, and degree of response to therapy. TRACP-5b should be investigated further as a potential biomarker to predict response to therapy, including slowing of radiographic progression.
authors.affiliation: Department of Rheumatology, First Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215000, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Cheng
authors.affiliation: Department of Rheumatology, First Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215000, China.
authors.forename: Mingjun
authors.initials: M
authors.lastname: Wang
authors.affiliation: Department of Rheumatology, First Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215000, China.
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Department of Rheumatology, University of Pennsylvania, Philadelphia 19104, USA.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Eisenberg
authors.affiliation: Department of Hematology, Subei People's Hospital, Yangzhou, Jiangsu 225001, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Rheumatology, Wuxi First People's Hospital, Wuxi, Jiangsu 214043, China.
authors.forename: Yaohong
authors.initials: Y
authors.lastname: Zou
authors.affiliation: Department of Rheumatology, First Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215000, China.
authors.forename: Yingsu
authors.initials: Y
authors.lastname: Deng
authors.affiliation: School of Public Health, Central South University, Changsha, Hunan 410083, China.
authors.forename: Mian
authors.initials: M
authors.lastname: Wang
authors.affiliation: Department of Nephrology, First Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215000, China. Email: zl66060@163.com.
authors.forename: Ling
authors.initials: L
authors.lastname: Zhou
mesh_terms: D000135:Acid Phosphatase / Q000097:blood*; D000293:Adolescent; D000328:Adult; D000911:Antibodies, Monoclonal / Q000627:therapeutic use; D001172:Arthritis, Rheumatoid / Q000097:blood* / Q000188:drug therapy; D015415:Biomarkers / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D000069285:Infliximab; D007527:Isoenzymes / Q000097:blood*; D008297:Male; D008727:Methotrexate / Q000627:therapeutic use; D008875:Middle Aged; D010010:Osteoclasts / Q000378:metabolism; D010865:Pilot Projects; D000071681:Tartrate-Resistant Acid Phosphatase; D055815:Young Adult
chemical_list: D000911:Antibodies, Monoclonal; D015415:Biomarkers; D007527:Isoenzymes; D000069285:Infliximab; C000605510:ACP5 protein, human; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase; D008727:Methotrexate