Experimental Study On The Effect Of NS-398 On Pathogenesis Of Fungal Keratitis

Objective Investigating the expression of COX-2 in fungal keratitis and normal cornea in order to study the lesion mechanisms of COX-2 to cornea and the effect of it's selective inhibitor NS-398 on the expression of MMP-2 in fungal keratitis of New Zealand white rabbit.Materials and methods 50 New Zealand white rabbits were devided into 4 groups at random, including group A ,B,C and D. Group A was control group, including 5 normal corneas. Group B was fungal keratitis group, including 30 corneas. After inoculating, the expression of COX-2 in 30 fungal keratitis (at 6h, 12h, 1d, 2d, 3d, 7d) and 5 normal corneas was detected by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and the corneas were given HE staining and light microscope study. Group C and D were fungal keratitis groups, each including 10 corneas.After inoculating , Group D was dropped with 100umol/L NS-398 at once. The expression of MMP-2 was detected by RT-PCR at 7d and 14d.Results 1. Histopathological examination: Light mictoscope revealed that fungal keratitis was a kind of suppurative inflammation, including the invasion of fungal hyphae and conidia and the infusion of neutrocytes in large quantity . 2. RT-PCR results : (l)There was no expression of COX-2 in normal cornea. 6h after inoculating, COX-2 mRNA was upregulated and up to peak at 3 days. At 7 d, it was about 30% of the 3 d and the difference was significant (P<0.01). (2) After inoculating, the expression of MMP-2 in Group D was lower than that in Group C at 7d and 14d , and the diference was significant (P<0.01). The expression of MMP-2 at 14d was lower than that at 7d, and the diference was significant (P<0.01).Conclusion These results suggest that the abnormal expression of COX-2 plays an important role in the occurrence and development of fungal keratitis. The high level of COX-2 may be an objective evidence of diagnosis. NS-398 can inhibit the expression of MMP-2 in fungal keratitis , which may be the basement of drug therapy and prevention of fungal keratitis.