Genestier L, Paillot R, Fournel S, Ferraro C, Miossec P, Revillard J P
Laboratory of Immunology, Institut National de la Santé et de la Recherche Médicale U80 Claude Bernard University, Hôpital E. Herriot, 69437 Lyon, France.
J Clin Invest. 1998 Jul 15;102(2):322-8. doi: 10.1172/JCI2676.
The folate antagonist methotrexate (MTX) is extensively used in graft-versus-host disease, rheumatoid arthritis, and other chronic inflammatory disorders. In addition to its antiinflammatory activity associated with increased release of adenosine, MTX exerts antiproliferative properties by inhibition of dihydrofolate reductase and other folate-dependent enzymes. However, the mechanisms of immunosuppressive properties associated with low-dose MTX treatments are still elusive. We report here that MTX (0.1-10 microM) induces apoptosis of in vitro activated T cells from human peripheral blood. PBL exposed to MTX for 8 h, then activated in drug-free medium, underwent apoptosis, which was completely abrogated by addition of folinic acid or thymidine. Apoptosis of activated T cells did not require interaction between CD95 (Fas, APO-1) and its ligand, and adenosine release accounted for only a small part of this MTX activity. Apoptosis required progression of activated T cells to the S phase of the cell cycle, as it was prevented by drugs or antibodies that interfere with IL-2 synthesis or signaling pathways. MTX achieved clonal deletion of activated T cells in mixed lymphocyte reactions. Finally, in vitro activation of PBL taken from rheumatoid arthritis patients after MTX injection resulted in apoptosis. Altogether, the data demonstrate that MTX can selectively delete activated peripheral blood T cells by a CD95-independent pathway. This property could be used as a new pharmacological end point to optimize dosage and timing of MTX administration. It may account for the immunosuppressive effects of low-dose MTX treatments.
叶酸拮抗剂甲氨蝶呤（MTX）广泛应用于移植物抗宿主病、类风湿性关节炎及其他慢性炎症性疾病。除了与腺苷释放增加相关的抗炎活性外，MTX还通过抑制二氢叶酸还原酶和其他叶酸依赖性酶发挥抗增殖特性。然而，低剂量MTX治疗相关的免疫抑制特性机制仍不清楚。我们在此报告，MTX（0.1 - 10微摩尔）可诱导人外周血体外活化T细胞凋亡。暴露于MTX 8小时的外周血淋巴细胞（PBL），然后在无药培养基中活化，会发生凋亡，添加亚叶酸或胸腺嘧啶核苷可完全消除这种凋亡。活化T细胞的凋亡不需要CD95（Fas，APO - 1）与其配体之间的相互作用，腺苷释放仅占MTX这种活性的一小部分。凋亡需要活化T细胞进入细胞周期的S期，因为干扰白细胞介素-2合成或信号通路的药物或抗体可阻止凋亡。MTX在混合淋巴细胞反应中实现了活化T细胞的克隆清除。最后，注射MTX后取自类风湿性关节炎患者的PBL体外活化导致凋亡。总之，数据表明MTX可通过不依赖CD95的途径选择性清除活化的外周血T细胞。这一特性可作为优化MTX给药剂量和时间的新药理学终点。它可能解释了低剂量MTX治疗的免疫抑制作用。
