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 immunohistochemistry 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.