目的探讨明胶酶包括基质金属蛋白酶(MMP)2与MMP-9在兔真菌性角膜炎病理改变中的作用。方法80只新西兰白兔随机分为4组,每组20只。其中3组为实验组,兔右眼分别注入100μl茄病镰刀菌、烟曲霉菌及白色念珠菌的悬液;另1组为对照组,兔右眼注入等量生理盐水。免疫组织化学方法观察MMP-2与MMP-9的来源,明胶酶谱法检测其活性。组织病理学方法观察炎性细胞的浸润、角膜细胞外基质(ECMs)的降解以及真菌菌丝在角膜内的生长方式与入侵深度。结果MMP-2主要由角膜基质细胞产生,真菌感染后5d检测出活性,8d活性升高。MMP-9主要来源于嗜中性粒细胞,接种后1d即检测到活性,3d活性升高,之后逐渐下降。茄病镰刀菌感染后3d,角膜内散在嗜中性粒细胞,浅层ECMs被降解,菌丝平行于角膜基质纤维生长。烟曲霉菌和白色念珠菌感染后3d,角膜内可见大量嗜中性粒细胞,周围ECMs降解明显,菌丝表现为垂直生长。接种后8d,茄病镰刀菌和白色念珠菌感染的角膜内炎性细胞和菌丝明显减少,而烟曲霉菌感染的角膜变化不明显。结论茄病镰刀菌、烟曲霉菌及白色念珠菌感染兔角膜后,产生的明胶酶活性明显不同;明胶酶对降解角膜ECMs发挥了重要作用;随着ECMs降解程度的不同,菌丝在角膜内的生长方式、入侵深度等病理改变出现差异。
Objective To study the roles of gelatinases, including matrix metalloproteinase (MMP)-2 and MMP-9, in pathological changes of fungal keratitis in rabbits. Methods Eighty New Zealand albino rabbits were randomly and equally divided into 4 groups, 3 of them were test groups, with Fusarium solani, Aspergillus fumigatus, and Candida albicans inoculated onto the right corneas, respectively. In the other group, sterile saline was injected onto the right corneas and was used as the control group. The source and activity of gelatinases were examined by immunohistochmistry and gelatin zymography, respectively. Hematoxylin-eosin stains was applied for observing infiltration of inflammatory cells and degradation of corneal extracellular matrixes (ECMs). Periodic acid-Schiff stain was used for studying hyphal growth patterns and the invasive depth in the cornea. Results MMP-2 was mainly produced by the keratocytes. Active MMP-2 was detected from day 5 after inoculation and increased greatly on day 8. MMP-9 was mostly produced by neutrophils, and active MMP-9 was detected from day 1 and increased to day 3, then decreased gradually. In A. fumigatus and C. albicans keratitis, the corneal ECMs were degraded obviously, the hyphae grew vertically, and the neutrophils were much more than those in F. solani keratitis whose hyphae grew horizontally and ECMs were degraded slightly. On day 8, the hyphae and neutrophils in F. solani and C. albicans keratitis decreased greatly compared with day 3, but did not change significantly in A. fumigatus keratitis. Conclusions There is significant difference in gelatinase activities in the rabbits' corneas infected by F. solani, A. fumigatus, and C. albicans. Gelatinases play important roles in the degradation of corneal ECMs. Hyphal growth pattern and invasive depth are depended on the difference of degradations of ECMs and show difference in various fungal keratitis.