Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Transplantation. 2013 Feb 15;95(3):434-41. doi: 10.1097/TP.0b013e31827a48f5.
Th17 responses have been suggested to participate in the pathogenesis of acute allograft rejection. RORγt is the master transcription factor that controls Th17 cell differentiation and expansion. However, little is known about the effect that antagonizing RORγt activity may have on acute cardiac allograft rejection.
A model of heterotopic murine cardiac transplantation with total allomismatch (BALB/c to B6 mice) was used. Digoxin, which was recently identified as a specific antagonist of RORγt, was injected intraperitoneally daily (40 μg) starting 1 day after cardiac transplantation. The severity of rejection was determined by histology. The mRNA expression levels of cytokines and transcription factors in the grafts were measured by quantitative real-time PCR. The proportion and number of T-cell subpopulations in the allografts and spleens were analyzed by flow cytometry. In vitro, the effect of digoxin on allogeneic responses and the interleukin (IL)-6-mediated conversion of regulatory T cells (Treg) into Th17 cells were investigated.
Treatment with digoxin significantly prolonged cardiac allograft survival compared with dimethyl sulfoxide treatment (mean survival time, 16.5±2.2 versus 8.1±0.7 days; P<0.01). Treatment with digoxin also markedly suppressed the mRNA expression levels of IL-17A, IL-17F, and granulocyte-macrophage colony-stimulating factor, reduced the number of Th17 cells, and induced Treg expansion in the allografts. In vitro, treatment with digoxin did not inhibit the proliferation of T cells in a mixed lymphocyte reaction, but it did inhibit the IL-6-mediated conversion of Tregs into Th17 cells.
RORγt may be a promising therapeutic target to attenuate acute cardiac allograft rejection. Digoxin therefore provides a molecular basis for the design of novel immunosuppressive agents.
Th17 反应被认为参与了急性同种异体移植物排斥反应的发病机制。RORγt 是控制 Th17 细胞分化和扩增的主转录因子。然而，对于拮抗 RORγt 活性可能对急性心脏同种异体移植排斥反应的影响知之甚少。
使用异基因小鼠心脏移植模型（BALB/c 到 B6 小鼠）。地高辛最近被鉴定为 RORγt 的特异性拮抗剂，从心脏移植后 1 天开始每天腹膜内注射（40μg）。通过组织学确定排斥反应的严重程度。通过定量实时 PCR 测量移植物中细胞因子和转录因子的 mRNA 表达水平。通过流式细胞术分析同种异体移植物和脾脏中 T 细胞亚群的比例和数量。在体外，研究了地高辛对同种异体反应的影响以及白细胞介素 (IL)-6 介导的调节性 T 细胞 (Treg) 向 Th17 细胞的转化。
与二甲基亚砜治疗相比，地高辛治疗显著延长了心脏移植物的存活时间（平均存活时间，16.5±2.2 与 8.1±0.7 天；P<0.01）。地高辛治疗还显著抑制了 IL-17A、IL-17F 和粒细胞-巨噬细胞集落刺激因子的 mRNA 表达水平，减少了 Th17 细胞的数量，并诱导了同种异体移植物中 Treg 的扩增。在体外，地高辛治疗不会抑制混合淋巴细胞反应中 T 细胞的增殖，但会抑制 IL-6 介导的 Treg 向 Th17 细胞的转化。
RORγt 可能是减轻急性心脏同种异体移植排斥反应的有前途的治疗靶点。因此，地高辛为设计新型免疫抑制剂提供了分子基础。
