Effects of immunocyte on the process of fungal keratitis

Background Infective keratopathy is a key cause of corneal blindness in China,and fungal keratitis is proved to have a higher incidence and bigger threats in infective keratitis.Researches showed that topical immunology plays an important effect during the development of fungal keratitis,but its mechanism is still studying.Objective This experiment was to explore the critical immunocyte during the process of fungal keratitis.Methods Forty-eight SPF 12-week-old male C57BL/6J mice were included and randomized into the control group and model group.The fungal keratitis model closely mimicking human cornea infections was established in the mouse using scratch followed by incubation of fusarium solani on the cornea,and the mice in the control group scratched on the cornea only.Cornea was examined under the slit lamp at 0,6,9,12,24,72 and 120 hours after operation.The severity of keratomycosis was clinically scored based on the literature criteria.The inflammatory cells were identified using immnofluorescence label,and the number of the inflammatory cells was calculated and compared among different groups and time points.This study complied with the Statement of ARVO in the use of experimental animal.Both Experimental Animal Ethic Commission in Zhengzhou University and Life Science Management Commission approved this study proposal.Results After inoculation of fusarium solani,typical fungul keratitis signs were seen on the cornea.Severe corneal opacifieation occurred within 24 hours and peaked at 72 hours.However,only mild edema of cornea was exhibited and gradually recovered normal in the control group within 24 hours.The clinical score of inflammation was higher in the model group in various time points than that in the control group,and it was seen that 24-72 hours after operation,the score attached peak in the model group with a significant difference in comparison with the control group(P＜0.01).In 9,12,24,72 and 120 hours after operation,the number of neutrophil cells was significantly increased in the model group compared with control group (P＜0.05),and that in 12,24,72 hours after operation was significantly higher than the 6 hours(P=0.004,0.000,0.001).However,no significant differences were seen in the number of neutrophil cells between 9 or 120 hours and 6 hours after operation(P=0.772,0.323).The number of T lymphocytes in cornea was significantly increased in 72 and 120 hours in comparison with 6 hours in the model group(P=0.000,0.000),and from 72 to 120 hours after operation,the number of T lymphocytes was significantly higher than that of the contral group (P＜0.01).The neutrophil cell number was positive correlated with the inflammatory score in the early phase (r =0.593,P =0.000).T limphocyte emerged in late phase but no significant correlation with the clinical score (r＝0.315,P=0.062).Conclusions Neutrophil cells play a critical role in the development of fungal keratitis in early stage. Key words: Cornea; Fungi/infection; Immunity/topical; Neutrophil cell; T lymphocyte