RT Journal Article
SR Electronic
T1 Increased Levels of Interleukin 34 in Serum and Synovial Fluid are Associated with Rheumatoid Factor and Anticyclic Citrullinated Peptide Antibody Titers in Patients with Rheumatoid Arthritis
JF The Journal of Rheumatology
JO J Rheumatol
FD The Journal of Rheumatology
SP jrheum.130356
DO 10.3899/jrheum.130356
A1 Su-Jin Moon
A1 Yeon-Sik Hong
A1 Ji Hyeon  Ju
A1 Seung-Ki Kwok
A1 Sung-Hwan Park
A1 Jun-Ki Min
YR 2013
UL http://www.jrheum.org/content/early/2013/08/29/jrheum.130356.abstract
AB Objective Interleukin 34 (IL-34) is a recently discovered cytokine that binds macrophage colony-stimulating factor (M-CSF) receptor. Rheumatoid arthritis (RA) is characterized by increased osteoclastogenesis. To identify the significance of IL-34 in RA, the IL-34 concentration was measured in serum and synovial fluid (SF). Methods IL-34 concentrations were measured in serum from patients with RA (n = 113), patients with osteoarthritis (OA; n = 56), and controls (n = 36), and in SF isolated from patients with RA (n = 36) or OA (n = 24). Correlations between serum IL-34 levels and clinical features in RA were assessed. The levels of IL-1β, IL-6, IL-17α, interferon-γ-induced protein 10, receptor activator of nuclear factor κB ligand (RANKL), and Dickkopf-1 were also measured. Results Patients with RA had a higher mean serum level of IL-34 than did patients with OA and controls (188.0 ± 550.3, 36.6 ± 38.0, and 49.1 ± 78.5 pg/ml, respectively). Similarly, SF IL-34 concentration was higher in patients with RA than in those with OA. IL-34 levels were positively associated with IL-6 levels in serum from patients with RA and OA. SF IL-34 concentration correlated significantly with IL-6 and RANKL levels only in RA. The serum level of IL-34 was not correlated with systemic osteoporosis and radiographic joint damage in RA. IL-34 levels in the serum from patients with RA were positively correlated with rheumatoid factor and anticyclic citrullinated peptide antibody titers (r = 0.282 and 0.491, respectively). Conclusion Circulating IL-34 levels in RA correlated with autoantibody production. Further investigations of localized and systemic effects of IL-34 are warranted to elucidate RA pathogenesis.