Neidel J, Sova L, Schroers B, Sintermann F, Manzke O, Bohlen H
Division of Orthopaedics, Centre for Rheumatology, Bad Bramstedt, Germany.
Ann Rheum Dis. 1998 Jul;57(7):414-21. doi: 10.1136/ard.57.7.414.
Methotrexate (MTX) has become the disease modifying drug of choice for the treatment of rheumatoid arthritis (RA). Direct effects of MTX on articular cartilage in vivo and in vitro were studied to determine possible adverse effects of the drug.
For in vitro experiments, adult bovine articular cartilage explants were cultured in the presence of MTX (0 to 100 microM), and effects on DNA and matrix metabolism were studied. For in vivo studies, 48 adult female rabbits were treated with MTX (30 mg/kg/week intramuscularly) or placebo, respectively, for up to 12 weeks, and effects on the cartilage of the femoral condyles were assessed.
In vitro, MTX dose dependently increased the uptake of [3H]-thymidine, and decreased incorporation of [3H]-d-uridine into chondrocytes with a half maximal effect at 0.03 microM, suggesting inhibition of thymidylate-synthetase activity by the drug. MTX also dose dependently reduced the proportion of chondrocytes in S-phase, as determined by flow cytometry. MTX did not affect LDH release from chondrocytes or the proportion of viable cells, nor did it change the rate of protein synthesis, proteoglycan synthesis, proteoglycan breakdown, or the hydrodynamic size of newly synthesised proteoglycans. In vivo, MTX did not appreciably affect proteoglycan synthesis of the chondrocytes, proteoglycan content of the cartilage matrix, density of the chondrocyte population, or histological integrity of the cartilage.
The data suggest the absence of major adverse effects by MTX on articular cartilage proteoglycan metabolism. Chondrocyte DNA metabolism seems to be changed by MTX only in concentrations and exposition periods clearly exceeding those found in synovial fluid of RA patients receiving the commonly prescribed doses of the drug.
甲氨蝶呤（MTX）已成为治疗类风湿关节炎（RA）的首选改善病情药物。本研究旨在探讨MTX在体内和体外对关节软骨的直接作用，以确定该药物可能存在的不良反应。
体外实验中，将成年牛关节软骨外植体置于MTX（0至100微摩尔）存在的条件下培养，研究其对DNA和基质代谢的影响。体内研究中，48只成年雌性兔子分别接受MTX（30毫克/千克/周，肌肉注射）或安慰剂治疗，最长治疗12周，评估其对股骨髁软骨的影响。
体外实验中，MTX剂量依赖性地增加了[3H] - 胸腺嘧啶核苷的摄取，并降低了[3H] - d - 尿苷掺入软骨细胞的量，在0.03微摩尔时达到半数最大效应，提示该药物抑制胸苷酸合成酶活性。通过流式细胞术测定，MTX还剂量依赖性地降低了处于S期的软骨细胞比例。MTX不影响软骨细胞释放乳酸脱氢酶或活细胞比例，也不改变蛋白质合成、蛋白聚糖合成、蛋白聚糖分解速率或新合成蛋白聚糖的流体力学大小。体内实验中，MTX对软骨细胞的蛋白聚糖合成、软骨基质的蛋白聚糖含量、软骨细胞群体密度或软骨的组织学完整性没有明显影响。
数据表明MTX对关节软骨蛋白聚糖代谢不存在主要不良反应。只有在浓度和暴露时间明显超过接受常规剂量该药物的RA患者滑液中发现的水平时，MTX才似乎会改变软骨细胞的DNA代谢。
