圆锥角膜中细胞凋亡及Fas-L蛋白的表达

Apoptosis in keratoconus and its relevance to the expression of Fas-L protein

目的探讨凋亡与圆锥角膜发病的关系及凋亡相关蛋白Fas-L的表达。方法对20例圆锥角膜及5例正常角膜用原位末端标记法(TUNEL)检测凋亡,用免疫组织化学SP法检测Fas-L蛋白的表达;透射电镜观察凋亡细胞的形态学变化。结果TUNEL染色示圆锥角膜组中上皮层、基质层及内皮层中细胞凋亡与正常角膜组比较差异均有统计学意义(P<0.05);免疫组织化学示圆锥角膜组与正常角膜组基质层间Fas-L表达比较差异有统计学意义(P<0.05);透射电镜可见圆锥角膜中存在凋亡特征的细胞。结论圆锥角膜中存在凋亡,Fas-L蛋白的表达存在异常,Fas-FasL系统可能在圆锥角膜细胞凋亡中发挥了重要作用。

Objective Keratoconus,a relatively common,bilateral,non-inflammatory corneal ectasia,is a leading indication for corneal transplantation, but its etiology remains unknown. This stady was to investigate the potential role of apoptosis and the expression of Fas-L protein in keratoeonus. Methods Five normal corneas from eyebank of Tongren Hospital and 20 keratoconus corneas obtained from penetrating karatoplasty were used as specimens in the study. Apoptosis was evaluated in the 20 keratoconus and 5 normal corneas using transferase-mediated dUTP-digoxigenin nick and labeting （TUNEL） assay. The feature of cell apoptosls in 4 keratoconus and 2 normal corneas was also revealed under the transmission electron microscope. The expression of Fas-L protein was detected by immunohistochemieal streptavidin-peroxidase （SP） method. Results All 20 keratoconus corneas demonstrated intense TUNEL staining in at least one layer of the cornea including epithelial layer,stromal and endothelial layer. In 20 keratoconus corneas, 19 exhibited staining in epithelial layer, 15 in stromal layer, and 11 in endothelial layer. Two of 5 normal corneas showed few TUNEL-positive staining only in epithelial layer and no staining in the stromal and endothelial layer. The difference in TUNEL-positive cell number between the keratoconus and normal corneas was statistically significant （P 〈 0.05）. Apoptosis of cell were detected under the transmission electron microscope in keratoconus corneas rather than in normal corneas. Fas-L protein was detected only in epithelial and endothelial layers but keratocytes in normal corneas, however, Fas-L protein was expressed in all three layers of cornea in 14 keratoconus corneas. Conclusion Apoptosis may play an important role in the pathogenesis of keratoeonous. The apoptosis induction may be related to Fas-FasL expression.