Department of Pharmacy Practice, University of Kansas Medical Center, Kansas City, KS, USA.
Division of Clinical Pharmacology, Toxicology and Therapeutic Innovation, Children's Mercy Kansas City, Kansas City, MO, USA.
Eur J Pharmacol. 2019 Jun 15;853:264-274. doi: 10.1016/j.ejphar.2019.03.052. Epub 2019 Apr 2.
Methotrexate (MTX) efficacy in autoimmune arthritis is variable and unpredictable resulting in the need for the identification of biomarkers to guide drug therapy. This study utilizes the collagen-induced arthritis mouse model to investigate erythrocyte MTX disposition and anti-folate activity as biochemical markers of efficacy in autoimmune arthritis. Following induction of arthritis, DBA/1J mice were treated with once-weekly subcutaneous MTX at varying doses over a period of 40 days. At the completion of the study tissue samples were analyzed for MTX and folate content and assessed for their relationship with MTX efficacy. MTX treatment resulted in a reduction in disease activity that was variable and dose-dependent. Erythrocyte accumulation of MTX and its polyglutamate metabolites were dose proportionate, however, polyglutamate metabolites represented a mean ± S.E.M. of 8.9 ± 0.4% of total erythrocyte MTX, which is markedly lower than previously observed in humans and failed to display any significant association with MTX efficacy. MTX treatment resulted in reductions in erythrocyte 5-methyl-tetrahydrofolate (5mTHF) levels that were similar to those previously observed in human studies. Disease induction was associated with a decrease in liver 5mTHF and increased formyl-tetrahydrofolate (fTHF) that was normalized in MTX treated mice. MTX efficacy was associated with reductions in erythrocyte 5mTHF (P = 0.04) and increases in liver 5mTHF (P = 0.0001). Together, these findings demonstrate a relationship between alterations in tissue folate levels and MTX efficacy, and supports erythrocyte levels of 5mTHF as a marker of MTX efficacy in autoimmune arthritis.
甲氨蝶呤（MTX）在自身免疫性关节炎中的疗效是可变且不可预测的，这导致需要确定生物标志物来指导药物治疗。本研究利用胶原诱导性关节炎小鼠模型来研究红细胞 MTX 分布和抗叶酸活性作为自身免疫性关节炎疗效的生化标志物。在关节炎诱导后，DBA/1J 小鼠接受每周一次皮下 MTX 治疗，剂量不同，持续 40 天。在研究结束时，分析组织样本中的 MTX 和叶酸含量，并评估其与 MTX 疗效的关系。MTX 治疗导致疾病活动度降低，这种降低是可变的且剂量依赖性的。红细胞 MTX 及其聚谷氨酸代谢物的积累与剂量成比例，然而，聚谷氨酸代谢物占红细胞 MTX 总量的平均±S.E.M.为 8.9±0.4%，明显低于之前在人类中观察到的水平，并且与 MTX 疗效没有显示出任何显著关联。MTX 治疗导致红细胞 5-甲基四氢叶酸（5mTHF）水平降低，与之前在人类研究中观察到的相似。疾病诱导与肝脏 5mTHF 降低和甲酰四氢叶酸（fTHF）增加有关，而 MTX 治疗的小鼠中 fTHF 增加得到了正常化。MTX 疗效与红细胞 5mTHF 降低（P=0.04）和肝脏 5mTHF 增加（P=0.0001）相关。这些发现共同表明组织叶酸水平的变化与 MTX 疗效之间存在关系，并支持红细胞 5mTHF 水平作为自身免疫性关节炎中 MTX 疗效的标志物。
