ICOS共刺激通路参与角膜移植免疫排斥反应的研究

目的研究可诱导共刺激分子（ICOS）共刺激通路与角膜移植急性免疫排斥反应的关系。方法建立大鼠同种异体穿透角膜移植模型，分别于术后7d、14d取植片进行病理学观察，采用RT-PCR法检测植片组织ICOS mRNA的表达情况，免疫组织化学法检测植片组织淋巴细胞ICOS蛋白水平；同时采用流式细胞术检测外周血CD3^＋ICOS^＋T／CD3^＋T的表达情况。均以正常大鼠作为正常对照。结果正常大鼠角膜组织未检测到ICOS蛋白及ICOS mRNA的表达，移植术后植片组织可以检测到ICOS蛋白及ICOS mRNA的表达，且术后14d高于术后7d（P=0．000）；与正常大鼠外周血CD3^＋ICOS^＋T／CD3^＋T的表达相比术后表达皆升高（方差齐性，P=0．156），且术后14d外周血CD3^＋ICOS^＋T／CD3^＋T的表达高于术后7d的表达（P=0．000）。结论共刺激分子ICOS与角膜移植急性免疫排斥反应密切相关。

The role of ICOS co-stimulatory passageway on corneal transplantation rejection

Objective Researches demonstrated that inducible co-stimulator （ ICOS）-mediated co-stimulatory passageway plays a critical role during multi-organ transplantation rejection. However, its influence on corneal graft rejection is unclear. Present study was to investigate the expression of ICOS protein and ICOS mRNA in rejected rat corneal allografts and the expression of CD3^＋ ICOS^＋ T/CD3^＋ T in rejected rat peripheral blood and explore the relationship between ICOS co-stimulator passageway and immune rejection. Methods Corneal allograft transplantation was performed orthotopically from 10 Wistar rats to 20 SD rats （ Wistar→ SD ）. Corneal samples were collected on day 7,14 postoperatively. Immunohistochemistry was used to detect the expression and distribution of ICOS protein in corneal grafts. RT-PCR was used for the detection of expression of ICOS mRNA. The expression of CD3^＋ ICOS^＋ T/CD3^＋ T in peripheral blood of SD rats was evaluated using flow cytometry. Ten healthy eyes from 5 normal SD rats were as control group. Results The grafts rejection occurred in postoperative day 14, showing the thickness increase of corneal grafts and infiltration of inflammatory cells. ICOS protein and ICOS mRNA were not detected in normal rat cornea but were expressed on graft tissue from 7 days through 14 days after transplantation and peaked on the 14th day after operation. Compared with the normal rats, CD3^＋ ICOS^＋ T/CD3^＋ T expression in peripheral blood was elevated on the 7th and 14th days after transplantation with the highest level on the 14th day. Conclusion The ICOS mRNA and ICOS protein are overexpressed in graft tissue during the allograft rejection. ICOS co-stimulatory passageway may be associated to the acute immune rejection after penetrating keratoplasty.