CXC chemokine CXCL12 is involved in the pathological development of rheumatoid arthritis (RA) through abnormal migration of peripheral immune cells in the joint. Although low dose methotrexate (MTX) is clinically used to treat RA patients, CXCL12 signaling responses to MTX-mediated treatments is still not well understood. In this study, we examined the expression of CXCR4 (cognatic receptor for CXCL12) in peripheral T cells from RA patients and arthritis mice models received from low dose MTX therapies. The effects of low dose MTX on CXCR4 were further determined via both in vitro CD3+ T cells and Cxcr4 conditional knockout (CKO) arthritis mice models. Our clinical data shows that low dose MTX treatment was clinically associated with down-regulated expression of chemokine receptor CXCR4 on patient peripheral T cells. In vitro, low dose MTX significantly decreased cell transmigration through down-regulated CXCR4’s expression in CD3+ T cells. Consistently, CD3+ T cells treated with low dose MTX demonstrated an increased genomic hypermethylation across the promoter region of Cxcr4 gene. Furthermore, our preclinical studies showed that low dose MTX-mediated downregulation of CXCR4 significantly improved the pathological development in mouse arthritis models. Conditional disruption of the Cxcr4 gene in peripheral immune cells potentially alleviated inflammation of joints and lung tissue in the arthritis mice, though genetic modification itself overall did not change their clinical scores of arthritis, except for a significant improvement on day 45 in CXCR4 CKO arthritis mice models during the recovery phase. Our findings suggest that the effect of low dose MTX treatment could serve to eliminate inflammation in RA patients through impairment of immune cell transmigration mediated by CXCR4.

中文翻译：

---

低剂量甲氨蝶呤通过下调类风湿性关节炎 (RA) 中 CXCR4 的表达而损害 T 细胞迁移


CXC趋化因子CXCL12通过关节内外周免疫细胞的异常迁移参与类风湿性关节炎（RA）的病理发展。尽管低剂量甲氨蝶呤（MTX）在临床上用于治疗 RA 患者，但 CXCL12 信号对 MTX 介导的治疗的反应仍不清楚。在这项研究中，我们检测了 RA 患者和接受低剂量 MTX 治疗的关节炎小鼠模型的外周 T 细胞中 CXCR4（CXCL12 的同源受体）的表达。通过体外 CD3+ T 细胞和 Cxcr4 条件敲除 (CKO) 关节炎小鼠模型进一步确定了低剂量 MTX 对 CXCR4 的影响。我们的临床数据表明，低剂量 MTX 治疗在临床上与患者外周 T 细胞上趋化因子受体 CXCR4 表达下调相关。在体外，低剂量 MTX 通过下调 CD3+ T 细胞中 CXCR4 的表达，显着减少细胞迁移。一致地，用低剂量 MTX 处理的 CD3+ T 细胞表现出 Cxcr4 基因启动子区域的基因组高甲基化增加。此外，我们的临床前研究表明，低剂量 MTX 介导的 CXCR4 下调显着改善了小鼠关节炎模型的病理发展。外周免疫细胞中 Cxcr4 基因的条件性破坏可能会减轻关节炎小鼠关节和肺组织的炎症，尽管基因改造本身总体上并没有改变关节炎的临床评分，除了 CXCR4 CKO 关节炎小鼠在第 45 天有显着改善之外恢复阶段的模型。 我们的研究结果表明，低剂量 MTX 治疗的作用可以通过损害 CXCR4 介导的免疫细胞迁移来消除 RA 患者的炎症。