TLR2单克隆抗体对大鼠角膜移植术后植片存活的保护作用

Protective role of anti-TLR2 monoclonal antibody to corneal graft survival after allograft corneal transplantation in rats

背景 Toll样受体2（TLR2）在移植免疫相关疾病中的作用越来越受到关注,阻断TLR2对心脏和肾脏移植物的保护作用已有研究报道,但TLR2是否具有抑制角膜移植排斥反应的作用尚未证实.目的 观察TLR2单克隆抗体对同种异体大鼠角膜移植术后植片存活情况的影响.方法 取24只SPF级雌性Wistar大鼠作为受体,12只SPF级SD大鼠作为供体,体质量均为180～220 g.采用同种异体角膜移植的方法在Wistar大鼠右眼实施穿透角膜移植术,制备大鼠角膜移植模型.采用随机数字表法将模型眼分为单纯模型组和TLR2单克隆抗体组,TLR2单克隆抗体组分别于术后0、2、4、6、8d球结膜下注射TLR2单克隆抗体15 μg/30μl,单纯模型组大鼠同法注射等容量生理盐水.术后每日于裂隙灯显微镜下观察各组大鼠角膜植片水肿程度、透明度和新生血管形成情况,参照Holland等的评分标准对排斥反应指数（RI）进行评分;分别于术后第9天、第15天收集各组3只大鼠角膜组织,另取3只正常Wistar大鼠眼球作为正常对照,行常规组织病理学检查.各组取6只大鼠用于生存分析观察.结果 术后1～4 d,裂隙灯显微镜下2个组角膜均轻度水肿,术后9～14d,单纯模型组大鼠角膜植片布满新生血管,可见植片水肿、混浊,而TLR2单克隆抗体组大鼠植片至术后第15天开始混浊.术后5、9、15d,单纯模型组大鼠RI评分均明显高于TLR2单克隆抗体组,差异均有统计学意义（t=4.183、4.954、13.506,均P＜0.05）;TLR2单克隆抗体组角膜植存活时间为15.5d,95％可信区间（CI）为14.9～16.1,单纯模型组角膜植片存活时间为9.5d,95％ CI为8.7～10.3,2个组间差异有统计学意义（Z=12.728,P=0.001）.角膜组织病理学检查显示,单纯模型组大鼠角膜基质层水肿明显,角膜组织中可见大量炎性细胞浸润和新生血管管腔形成,而在TLR2单克隆抗体组中仅见少量炎性细胞和新生血管.结论 TLR2单克隆抗体能减轻角膜移植术后的炎症反应,延长角膜植片的存活时间.

Background The effects of Toll-like receptor 2 （TLR2） in grafting-related immune diseases have attracted more and more attention.Blocking TLR2 signal pathway can extend the survival time of heart and kidney grafts.However, the effects of anti-TLR2 monoclonal antibody on corneal graft have not been confirmed.Objective This study was to investigate the influence of anti-TLR2 monoclonal antibody on corneal graft survival in the rats received penetrating keratoplasty （PKP）.Methods Allograft corneal transplantation was performed on the right eyes of 24 SPF female Wistar rats to establish PKP models,with 12 SD rats as donors.The model eyes were randomized into the TLR2 monoclonal antibody group and the model group.Anti-TLR2 monoclonal antibody of 15 μg/30 μl was subconjunctivally injected on day 0,2,4,6 and 8 following the modeling in the TLR2 monoclonal antibody group,and equal amount of normal saline was injected in the same way in the model group.The edema,transparency and neovascularization were observed under the slit lamp microscope after surgery, and rejection index （RI） was scored based on the criteria of Holland.Corneal tissue sections of the rats were prepared for the histopathological examination on day 9 and 15 after operation.The research protocol was approved by the Southern Medical University Ethics Committee.Results Mild corneal edema was found in the two groups 1-4 days after operation.A lot of new blood vessels, edema and opacification of corneas were seen in the model group 9-14 days after operation,but in the TLR2 monoclonal antibody group,corneal opacification was found 15 days after operation.The RI scores were significantly higher in the model group than those in the TLR2 monoclonal antibody group 5,9,15 days after operation （t=4.183,4.954,13.506;all at P〈0.05）.The survival time in the TLR2 monoclonal antibody group was 15.5 days,with the 95% confidence interval （CI） 14.9-16.1;while that in the model group was 9.5 days,with the 95% CI 8.7-10.3, showing a significant difference between the two groups （Z =12.728,P =0.001）.The corneal histopathological examination revealed that corneal stromal edema,infiltration of inflammatory cells and vascular lumen were more prominent 9 and 15 days after operation in the model group than those in the TLR2 monoclonal antibody group.Conclusions Anti-TLR2 monoclonal antibody can inhibit inflammatory response after allograft corneal transplantation and therefore extend the survival time of graft in rats.