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Urinary pyridinoline (U-Py) is a useful marker of bone and cartilage loss in rheumatoid arthritis (RA) . The serum pyridinoline (S-Py) concentration instead of U-Py was measured both in rats with adjuvant-induced (AA) and mice with collagen-induced (CIA) arthritis by high perfomance liquid chromatography (HPLC) . On the seventh day after adjuvant innoculation, the AA rats showed a significant increase in S-Py levels. The level of S-Py was gradually increased with the development of AA. Moreover, in CIA mouse, another arthritic model, on sixty days after innoculation of the type II collagen the S-Py level was also significantly higher than that in the normal mice.These findings indicate that the measurement of S-Py instead of U-Py may be useful as marker of bone and cartilage destruction in patients with rheumatoid arthritis.

Effects of anti-rheumatic drugs, gold sodium thiomalate (GST), methotrexate (MTX), D-penicillamine (D-P) and bucillamine (BU), on rhIL-1β-induced nitric oxide (NO) production in rat synovial fibroblast-like cells (SFC) cultured in vitro were investigated. The SFC (passage 4) were cultured for 48hrs in Dulbecco's modified Eagle's medium containing an NO inducer, LPS or rhIL-1β. NO production by SFC was assessed by using Griess reagent. RhIL-1β but not LPS, induced a significant increase in NO production in SFC. The rhIL-1β-induced NO production was inhibited by the presence of GST in a dose dependent manner, whereas MTX (100 ng/ml) had no effect. In contrast, both D-P (10 μg/ml) and BU (3 μg/ml) significantly stimulated rhIL-1β-induced NO production in SFC. This effect of SH-containing antirheumatic drugs was completely abolished by the presence of NO inhibitors, aminoguanidine (AG : 1 mM) and cycloheximide (CH : 2 μM) . AG but not CH, added at a later stage of culture (24-48hrs) abolished rhiL 1β induced NO production, indicating that these SH-compounds stimulate NO synthase activity in SFC.The present study suggests that SH-anti-rheumatic drugs stimulate rhIL-1β-induced NO production in SFC, and that the increase in NO may partly inhibit the bone destruction in rheumatoid arthritis.

Nitric oxide (NO) produced by the inducible NO synthase (iNOS) in the some tissue is associated with acute and chronic inflammatory process. This study is to examine that the effect of methotrexate (MTX) on the NO production from rat peritoneal macrophages by the iNOS. Macrophages from normal rats were cultured in the presence of drug followed by activation with lipopolysaccharide (LPS) . After 24 hrs, NO-2 as a metabolite of NO was measured by Griess reaction. MTX, bucillamine (BU), and indomethacin (IM) did not influence on the NO-2 accumulation with LPS. Aminoguanidine (AG), a preferential inhibitor of iNOS, and dexamethasone (DEXA) abolished NO-2 accumulation with LPS in concentration dependent manner.On the other hand, adjuvant-induced arthritis (AA) was induced in rats by the injection of Mycobacterium tuberculosis into the right hind foot pad. Drugs were administered daily by the oral route from day 1 to day 21. On day 22, macrophages from AA rats had an enhanced capacity to produce NO in vitro. MTX (0.1 mg/kg), DEXA (0.5 mg/kg) and IM (1 mg/kg) reduced the paw swelling and inhibited the increased NO production by macrophages. AG (100 mg/kg) only partly inhibited the increased NO production, while BU (10 mg/kg) did not influence the paw swelling and the increased NO production.Our data revealed that oral administration of MTX to AA rats significantly inhibited ex vivo LPS-induced NO production from peritoneal macrophages in accordance with its in vivo prophylactic effect of arthritis, suggesting that NO blockade might be one of the important mode of action for MTX in animal models of arthritis.