基质细胞衍生因子-1与趋化因子受体4在大鼠角膜移植排斥反应中的作用

Role of stromal cell-derived factor-1 and CXC chemokine receptor 4 in corneal graft rejection in rats

目的探讨基质细胞衍生因子-1(SDF-1)与基质细胞衍生因子-1(CXCR4)在大鼠角膜组织中的表达及其在角膜移植术后免疫排斥反应中的作用。方法取15只Wistar大鼠作为正常对照组;取22只Wistar大鼠行自体角膜移植术作为自体组;取22只SD大鼠与44只Wistar大鼠,以SD大鼠为供体,Wistar大鼠为受体行穿透性角膜移植,术后随机抽取22只归入典必殊组,术眼滴典必殊眼液(每日2次),剩余22只归入异体组,术眼滴同等量生理盐水,共一个月。参照Larkin法对各组角膜植片进行临床评估;分别于术后第5、9天取术眼角膜植片,行组织病理学观察、免疫组化检查、实时荧光定量PCR检测。结果自体组不发生排斥反应,典必殊组角膜存活时间为24±0.32 d,远高于异体组10±0.36 d(P<0.001)。组织病理学检查发现异体组角膜有大量炎性细胞浸润以及新生血管形成。SDF-1和CXCR4 mRNA在异体组角膜组织中表达水平明显升高(第5天P<0.001,第9天P<0.01),典必殊组较异体组明显降低。免疫组化检查发现SDF-1/CXCR4主要表达在角膜植片的上皮层与基质层,异体组角膜组织SDF-1和CXCR4含量明显升高。结论 SDF-1/CXCR4可能参与了大鼠角膜移植术后早期的排斥反应,其机制可能为SDF-1特异性诱导CXCR4+细胞成熟和朝着排斥部位趋化,并促进角膜新生血管形成。

Objective To examine expression of stromal cell-derived factor-1（SDF-1） and CXC chemokine receptor 4（CXCR4） in rat cornea tissue and their role in corneal allograft rejection. Methods With 15 Wistar rats as the normal control group, 22 Wistar rats received autologous corneal graft transplantation, and 44 Wistar rats received transplantation of corneal graft from SD rats with penetrating keratoplasty. From the rats with allograft transplantation, 22 were selected randomly for treatment with Tobra Dex eye drops for 30 days after the operation（twice a day）, and the remaining 22 rats were treated with normal saline only. Clinical assessment of the corneal grafts was carried out using Larkin＇s method; histopathological observation,immunohistochemistry, and real-time quantitative PCR of the corneal grafts were performed on days 5 and 9 after the transplantation. Results Graft rejection occurred in none of the rats in autograft group. In rats treated with Tobra Dex, the graft survival time was significantly longer than that in rats with saline treatment（24 ± 0.32 vs 10 ± 0.36 days, P〈0.001）, and histopathological examination revealed numerous inflammatory cells and neovascularization in the allografts in the latter group. SDF-1 and CXCR4 mRNA expression in the corneal tissue increased significantly in rats receiving allograft transplantation and saline treatment（P〈0.001 on day 5 and P〈0.01 on day 5）, and their expression was obviously lowered in rats with Tobra Dex treatment. Immunohistochemical examination revealed that the expression of SDF-1 and CXCR4, found mainly in the corneal epithelium and stroma, was significantly increased in the allografts in rats with saline treatment.Conclusion SDF-1/CXCR4 may participate in corneal graft rejection in rats early after transplantation possibly through the mechanism that SDF-1 specifically induces CXCR4＋cell maturation and chemotaxis toward the allograft to promote corneal neovascularization.