The active metabolite of leflunomide, A771726, inhibits both the generation of and the bone-resorbing activity of osteoclasts by acting directly on cells of the osteoclast lineage
The active metabolite of leflunomide, A771726, inhibits both the generation of and the bone-resorbing activity of osteoclasts by acting directly on cells of the osteoclast lineage
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DOI：
10.1007/s00774-003-0489-4
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发表时间：
2004-07-01
影响因子：
3.3
通讯作者：
Hakeda, Y
中科院分区：
文献类型：
--
作者：
Kobayashi, Y;Ueyama, S;Hakeda, Y
来氟米特是一种改善疾病的抗风湿药物，可抑制II型胶原诱导的小鼠关节炎的足跖肿胀和关节破坏，并通过阻断其活性代谢物A771726的去novo嘧啶生物合成，抑制T细胞的增殖和细胞因子的产生，从而延缓类风湿性关节炎（RA）患者的疾病进展。然而，来氟米特对类风湿关节炎中负责骨破坏的破骨细胞系的直接作用仍有待澄清。本研究通过体外培养骨髓源性破骨细胞祖细胞和纯化功能成熟的破骨细胞，考察了A771726对破骨细胞形成和骨吸收活性的影响，并阐明了A771726对破骨细胞作用的分子机制。在核因子κ B受体激活剂（nf - κ B）配体（RANKL）存在的情况下，A771726以剂量相关的方式抑制巨噬细胞集落刺激因子（M-CSF）依赖的破骨细胞祖细胞的破骨细胞形成，而不存在任何其他类型的细胞，类似于未分离骨髓细胞培养中的抑制作用。此外，A771726还能抑制成熟破骨细胞的骨吸收。这些结果表明，A771726直接和内在地抑制破骨细胞谱系细胞的分化和功能，而不需要其他细胞的介导。同时加入尿苷不能恢复A771726的抑制作用，可能与阻断NF-kappaB活化和酪氨酸磷酸化无关。因此，来氟米特通过其活性代谢物，有可能通过直接抑制破骨细胞生成和破骨细胞功能来预防骨质流失。这种抑制作用提示来氟米特延缓类风湿性关节炎患者关节破坏的新机制。
Leflunomide is a disease-modifying antirheumatic drug that inhibits paw swelling and joint destruction in type II collagen-induced arthritis in mice and it also delays disease progression in patients with rheumatoid arthritis (RA), through inhibiting proliferation and cytokine production of T cells, via the blocking of de-novo pyrimidine biosynthesis by its active metabolite, A771726. However, the direct action of leflunomide on cells of osteoclast lineage responsible for bone destruction in RA remains to be clarified. In this study, we examined the effect of A771726 on osteoclast formation and bone-resorbing activity in vitro, using cultures of bone marrow-derived osteoclast progenitors and purified functionally mature osteoclasts, and then we elucidated the molecular mechanism of action of the effect of A771726 on osteoclasts. A771726 inhibited osteoclast formation from macrophage colony-stimulating factor (M-CSF)-dependent osteoclast progenitors in the presence of receptor activator of nuclear factor kappa B (NF-kappaB) ligand (RANKL), without any other types of cells present, in a dose-related manner, similar to the inhibition in cultures of unfractionated bone marrow cells. In addition, A771726 suppressed bone resorption by isolated mature osteoclasts. These results indicate that A771726 directly and intrinsically inhibited the differentiation and function of osteoclast lineage cells without any mediation by other cells. The inhibition by A771726 was not restored by the simultaneous addition of uridine, and may be independent of the blockade of NF-kappaB activation and the tyrosine phosphorylation of proteins. Thus, leflunomide, through its active metabolite, has the potential to prevent bone loss by directly inhibiting osteoclastogenesis and osteoclast function. This inhibition suggests a novel mechanism for leflunomide in the retardation of the joint destruction observed in RA patients.