Positive correlation between levels of IL-1 or IL-2 and 1,25(OH)2D/25-OH-D ratio in synovial fluid of patients with rheumatoid arthritis.
The present study determined the levels in synovial fluid (SF) of vitamin D metabolites (1,25-dihydroxyvitamin D (1,25(OH)2D), 24,25-dihydroxyvitamin D (24,25(OH)2D) and 25-hydroxyvitamin D (25-OH-D)), and of the cytokines. We evaluated SF from 21 patients with rheumatoid arthritis (RA) and 6 patients with osteoarthritis (OA). The levels of vitamin D metabolites in SF, as determined by two different extraction methods, were significantly correlated (p < 0.05, n=7). The levels of 3 vitamin D metabolites were significantly higher in the RA SF than in OA SF (p < 0.05). The ratio of 1,25(OH)2D/25-OH-D in RA SF, which is presumed to reflect the activity of 25-OH-D-1-hydroxylase (1-OH-ase), was positively correlated with the levels of interleukin-1alpha (IL-1alpha), IL-1beta, and IL-2 in such SF, and was significantly higher than that in sera from RA patients. This suggests an important role for these cytokines in the activation of 1-OH-ase in RA synovium. The ratio of 24,25(OH)2D/25-OH-D, which is presumed to reflect 25-OH-D-24-hydroxylase (24-OH-ase) activity, was significantly correlated with 1,25(OH)2D levels only in RA SF, but not in sera from RA patients, suggesting a local regulation of vitamin D metabolism that 1,25-(OH)2D induces 24-OH-ase as in other target cells. Our observations suggested that 1,25(OH)2D and 24,25(OH)2D are produced locally from 25-OH-D in RA synovium, and that the syntheses of 1,25(OH)2D and 24,25(OH)2D may be affected by IL-1/IL-2 and 1,25(OH)2D in RA SF, respectively.
Inaba
M
M
Second Department of Internal Medicine, Osaka City University Medical School, Osaka, Japan.
Yukioka
K
K
Furumitsu
Y
Y
Murano
M
M
Goto
H
H
Nishizawa
Y
Y
Morii
H
H
D001172:Arthritis, Rheumatoid / Q000378:metabolism*; D006801:Humans; D007375:Interleukin-1 / Q000378:metabolism*; D007376:Interleukin-2 / Q000378:metabolism*; D013582:Synovial Fluid / Q000378:metabolism*; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000378:metabolism
D007375:Interleukin-1; D007376:Interleukin-2; D014807:Vitamin D; C097949:1,25-dihydroxyvitamin D; C104450:25-hydroxyvitamin D