title: Comparative study of serum and synovial fluid interleukin-11 levels in patients with various arthritides.
abstract: OBJECTIVE
  To determine the levels of serum and synovial fluid (SF) interleukin (IL)-11 in patients with various arthritides and estimate the contribution of IL-11 to acute phase response (APR).
  
  
  METHODS
  Serum and SF IL-11 were measured by ELISA in patients with rheumatoid arthritis (RA, n = 31), seronegative spondyloarthritis (SSA, n = 23), gout (GT, n = 14) and osteoarthritis (OA, n = 20) and were correlated with ESR and acute phase proteins as well as with cytokines IL-1 alpha, IL-1 beta, IL-6, and TNF alpha.
  
  
  RESULTS
  IL-11 was detected in both serum and SF in each group, with IL-11 being statistically higher in SF than serum in all groups, suggesting reduced catabolism or increased synthesis of IL-11 intra-articularly. Median SF IL-11 levels were higher in OA patients than in other groups and in the treated than in the untreated RA subgroup. Moreover, serum and SF IL-11 were correlated significantly with each other, and moderately with the other cytokines examined in RA, SSA, and GT, but not in OA patients, while a significant negative correlation was found with a few of the inflammatory markers examined in each group.
  
  
  CONCLUSIONS
  Our findings provide evidence of extensive intra-articular expression of IL-11 in arthritides, especially in OA and treated RA patients, suggesting a protective role for IL-11 in joints, probably through the induction of tissue inhibitor of metalloproteinases.
authors.affiliation: Department of Experimental Physiology, Medical School, University of Athens, Greece.
authors.forename: P
authors.initials: P
authors.lastname: Trontzas
authors.forename: E F
authors.initials: EF
authors.lastname: Kamper
authors.forename: A
authors.initials: A
authors.lastname: Potamianou
authors.forename: N C
authors.initials: NC
authors.lastname: Kyriazis
authors.forename: H
authors.initials: H
authors.lastname: Kritikos
authors.forename: J
authors.initials: J
authors.lastname: Stavridis
mesh_terms: D000209:Acute-Phase Proteins / Q000378:metabolism*; D000210:Acute-Phase Reaction / Q000378:metabolism; D001168:Arthritis / Q000378:metabolism*; D001172:Arthritis, Rheumatoid / Q000503:physiopathology; D015415:Biomarkers; D002097:C-Reactive Protein / Q000378:metabolism; D002570:Ceruloplasmin / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005293:Ferritins / Q000378:metabolism; D005340:Fibrinogen / Q000378:metabolism; D006073:Gout / Q000503:physiopathology; D006242:Haptoglobins / Q000378:metabolism; D006801:Humans; D005779:Immunodiffusion; D007375:Interleukin-1 / Q000378:metabolism; D017370:Interleukin-11 / Q000097:blood* / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D009391:Nephelometry and Turbidimetry; D009961:Orosomucoid / Q000378:metabolism; D010003:Osteoarthritis / Q000503:physiopathology; D011228:Prealbumin / Q000378:metabolism; D011446:Prospective Studies; D013223:Statistics as Topic; D018709:Statistics, Nonparametric; D013582:Synovial Fluid / Q000378:metabolism*; D014168:Transferrin / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D000515:alpha 1-Antitrypsin / Q000378:metabolism; D000511:alpha-Macroglobulins / Q000378:metabolism; D001613:beta 2-Microglobulin / Q000378:metabolism
chemical_list: D000209:Acute-Phase Proteins; D015415:Biomarkers; D016207:Cytokines; D006242:Haptoglobins; D007375:Interleukin-1; D017370:Interleukin-11; D015850:Interleukin-6; D009961:Orosomucoid; D011228:Prealbumin; D014168:Transferrin; D014409:Tumor Necrosis Factor-alpha; D000515:alpha 1-Antitrypsin; D000511:alpha-Macroglobulins; D001613:beta 2-Microglobulin; D005340:Fibrinogen; D002097:C-Reactive Protein; D005293:Ferritins; D002570:Ceruloplasmin