熊果酸对大鼠角膜移植排斥反应的抑制作用

Ursolic acid inhibits corneal graft rejection following orthotopic allograft transplantation in rats

目的探讨熊果酸对大鼠角膜移植排斥反应的治疗效果。方法以SD大鼠为供体,Wistar大鼠为受体,将48只Wistar大鼠随机分为4组。A组为正常角膜对照组,B组为Wistar鼠自体原位角膜移植,C、D组为SD-Wistar大鼠之间进行同种异体角膜移植。术后当天腹腔给药,A、B、C三组分别给予生理盐水作为空白对照,D组给予熊果酸(UA)(20 mg·kg-1·d-1),连续给药12 d。根据Larkin等角膜排斥反应评分系统,判断术后植片排斥情况。比较角膜植片的存活时间和植片存活率。术后14 d检测各组中IL-2、IFN-γ、NF-κBp65、VEGF及ICAM-1的表达含量,并对角膜植片进行组织学检查与Western blot分析。结果 D组角膜植片的存括时间为29.12±9.58 d,与C组9.67±2.16 d相比,两组间差异有显著性意义(P<0.01)。术后14 d D组角膜植片中的IL-2、IFN-γ、NF-κBp65、ICAM-1及VEGF的相对含量明显下降,而IκB-α蛋白含量较高。未见明显淋巴细胞浸润和新生血管形成。结论熊果酸作为NF-κB的核因子抑制剂,可以抑制角膜新生血管的形成与排斥反应,从而显著延长大鼠角膜植片的存活时间。

Objective To investigate the effects of ursolic acid on corneal graft rejection in a rat model of othotopic corneal allograft transplantation. Methods Forty-eight recipient Wistar rats were divided into normal control group with saline treatment （group A）, autograft group with saline treatment （group B）, SD rat allograft group with saline treatment （group C）, and SD rat allograft group with intraperitoneal ursolic acid （UA） treatment group （group D）. The rats received saline or UC （20 mg ·kg-1 · d-1） treatment for 12 days following othotopic graft transplantation. The grafts were evaluated using the Larkin corneal rejection rating system, and the graft survival was assessed with Kaplan-Meier analysis. On day 14, the grafts were harvested for histological examination, Western blotting, and assessment of expressions of interlukin-2 （IL-2）, interferon-γ（IFN-γ）, nuclear transcription factor-κB （NF-κB） p65, vascular endothelial growth factor （VEGF） and intercellular adhesion molecule-1 （ICAM-1）. Results The allograft survival was significantly longer in group D than in group C （29.12±9.58 vs 9.67± 2.16 days, P〈0.05）. UC treatment obviously reduced the expression levels of IL-2, IFN-γ, NF-κBp65, ICAM-1 and VEGF and increased inhibitory kappa B alpha （IκB-α） expression in the grafts, where no obvious inflammatory cell infiltration or corneal neovascularization was found. Conclusion As a NF-κB inhibitor, ursolic acid can prevent corneal neovascularization and corneal allograft rejection to promote graft survival in rats following orthotopic corneal allograft transplantation.