TLR2在大鼠穿透性角膜移植术后免疫排斥反应中的作用

Role of Toll-like receptor 2 in corneal graft rejection following penetrating keratoplasty

目的通过采用实时荧光定量PCR技术(RT-PCR)动态检测大鼠角膜组织TLR2mRNA的表达,研究TLR2在穿透性角膜移植术后免疫排斥反应中的作用。方法实验分四组:正常对照组(N)、同种同体角膜移植组(A)、同种异体角膜移植组(B)和同种异体角膜移植激素抗排斥组(C),A、B、C三组大鼠给予穿透性角膜移植术,术后裂隙灯下观察角膜透明度、新生血管并用排斥反应指数评分;分别于术后第5、7、9天取材,行组织病理学检查和荧光实时定量PCR检测,动态观察角膜组织TLR2 mRNA的表达。结果术后随时间变化角膜植片均出现不同程度的水肿、混浊、新生血管生长。B组大鼠角膜排斥反应指数平均在术后第7天符合排斥反应的诊断并获病理学支持;A组和C组大鼠角膜的排斥反应指数计分未达到诊断标准。正常的角膜组织可见TLR2 mRNA表达;三个手术干预组TLR2 mRNA表达差异倍数均明显高于正常对照组,同种异体角膜移植组角膜TLR2 mRNA的表达较同种同体角膜移植组显著增加,激素抗排斥组角膜TLR2 mRNA表达较同种异体角膜移植组显著降低(P<0.05)。结论TLR2可能作为天然免疫识别受体识别移植抗原,参与角膜移植术后免疫排斥反应。

Objective To gain insight into the role of Toll-like receptor 2 （TLR2） in graft rejection following penetrating keratoplasty, and investigate the expression of TLR2 mRNA in the corneal graft. Methods Penetrating keratoplasty was performed in 3 groups of rats for orthotopic autologous corneal transplantation （group A）, allograft corneal transplantation （group B）, or allograft corneal transplantation with hormone treatment （C）. The transparency and neovascularization of the cornea were observed using a slit-lamp microscope and scored according to the rejection index, with normal cornea serving as the control The corneal tissues were sampled at 5, 7, and 9 days after the transplantation for histopathological examination and detection of TLR2 mRNA expression using RT-PCR. Results With the passage of time, edema, opacities and neovascularization of the corneal graft occurred after the operation in all the groups. Seven days after the operation, the rejection index of group B, but not that of groups A and C, met the diagnostic criteria for graft rejection with also support by histopathological evidence. The expression of TLR2 mRNA was detected in normal comeas and augmented in the corneal grafts in the 3 transplantation groups. TLR2 mRNA expression in group B was significantly higher than that of group A, and the expression in group C decreased significantly in comparison with that in group B （P〈0.05）. Conclusion As the recognition receptors of native immune system, TLR2 in the rejected corneal grafts may recognize the allograft antigen and play a role in acute graft rejection after penetrating keratoplasty.