The Key Laboratory of Myocardial Ischemia, Chinese Ministry of Education, Harbin, Heilongjiang Province, China; Department of Cardiology, Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang Province, China.
The Key Laboratory of Myocardial Ischemia, Chinese Ministry of Education, Harbin, Heilongjiang Province, China.
PLoS One. 2014 May 5;9(5):e96138. doi: 10.1371/journal.pone.0096138. eCollection 2014.
The immunosuppressant Protosappanin A (PrA), isolated from the medicinal herb, promotes cardiac allograft survival, diminishes inflammatory cell infiltration, and inhibits interferon γ-induced protein 10 kDa (IP-10) mRNA expression in rats cardiac grafts. Binding of the chemokine IP-10 to its cognate receptor, CXCR3, plays crucial roles in allograft immunity, especially by mediating the recruitment of effector T cells to allografted tissues. In this study, we attempted to determine whether PrA-mediated inhibition of IP-10 contributes to the effect of reduced T cell infiltration into cardiac allograft within a rat model. Administration of PrA (25 mg/kg daily) via oral gavage following heart transplantation significantly reduced the increase of IP-10 mRNA level in allograft and prevented IP-10 secretion by peripheral blood mononuclear cells (PBMC) isolated from recipient rats seven days posttransplantation. Furthermore, in vitro experiments demonstrated that PrA addition to control PBMC prevented IP-10 secretion. Chemotactic migration assays were utilized to evaluate recipient T cell migration towards PBMC supernatant. PrA administration impaired PBMC supernatant-induced T cell migration. Additional in vitro experiments revealed that PrA slightly reduced naïve T cell migration towards chemokines. The presence of IP-10 in PBMC supernatant prevented PrA from reducing T cell migration in PrA-treated recipients. Neither CXCR3 chemokine ligand Mig nor non-CXCR3 chemokine ligand SDF-1 had any effect on T cell migration in PrA-treated recipients. The addition of anti-CXCR3 antibody restored PrA-mediated inhibition of T cell migration. Immunofluorescence microscopy showed that IP-10 was expressed mainly in CD68 positive infiltrating monocytes. Furthermore, PrA consistently reduced CXCR3+T cell infiltration into cardiac allografts. The reduced intensity of CXCR3 staining in PrA-treated allografts contributed to the previously depressed naïve T cell migrating activity induced by PrA. Collectively, these data indicate that PrA inhibition of IP-10 activity reduced recipient T cell migration and infiltration of cardiac allografts, thus partially explaining the immunosuppressive effect of PrA.
从药用植物中分离出的免疫抑制剂Protosappanin A（PrA）可促进心脏移植物的存活，减少炎性细胞浸润，并抑制大鼠心脏移植物中干扰素 γ 诱导的 10 kDa 蛋白（IP-10）mRNA 的表达。趋化因子 IP-10 与其同源受体 CXCR3 的结合在移植物免疫中起着至关重要的作用，特别是通过介导效应 T 细胞向移植物组织的募集。在这项研究中，我们试图确定 PrA 介导的 IP-10 抑制是否有助于减少大鼠心脏移植模型中 T 细胞浸润到心脏移植物中。心脏移植后，通过口服灌胃给予 PrA（每天 25mg/kg）可显著降低移植物中 IP-10 mRNA 水平的升高，并防止受体大鼠移植后 7 天外周血单个核细胞（PBMC）中 IP-10 的分泌。此外，体外实验表明，向对照 PBMC 中添加 PrA 可防止 IP-10 的分泌。趋化迁移实验用于评估受体 T 细胞向 PBMC 上清液的迁移。PrA 给药可损害 PBMC 上清液诱导的 T 细胞迁移。进一步的体外实验表明，PrA 略微减少了幼稚 T 细胞向趋化因子的迁移。PBMC 上清液中 IP-10 的存在阻止了 PrA 降低接受 PrA 治疗的受体中 T 细胞的迁移。CXCR3 趋化因子配体 Mig 和非 CXCR3 趋化因子配体 SDF-1 对接受 PrA 治疗的受体中 T 细胞的迁移均无影响。添加抗 CXCR3 抗体恢复了 PrA 介导的 T 细胞迁移抑制。免疫荧光显微镜显示 IP-10 主要在 CD68 阳性浸润的单核细胞中表达。此外，PrA 一致减少了心脏移植物中 CXCR3+T 细胞的浸润。PrA 处理的移植物中 CXCR3 染色强度降低，导致 PrA 诱导的幼稚 T 细胞迁移活性降低。总的来说，这些数据表明 PrA 抑制 IP-10 活性可减少受体 T 细胞的迁移和心脏移植物的浸润，从而部分解释了 PrA 的免疫抑制作用。
