Expression and effect of nucleotide oligomerization domain-like receptors in the initial of Aspergillus fumigatus keratitis in rats / 中华实验眼科杂志

ABSTRACT

Background Studies have determined that nucleotide binding oligomerization domain 2 (NOD2) plays a key role in innate immune response.However,whether NOD2 participates in the nature defense of fungal keratitis is unclear.Objective This study was to investigate the expression and significance of NOD2 on cornea in the initial of Aspergillus fumigatus keratitis (AFK) in rats.Methods Seventy-two adult clean Wistar rats were randomized into the normal control group,only corneal epithelial scraped group and AFK model group,and the AFK models were established by incubating Aspergillus fumigatus to cornea after corneal epithelium was scraped.All the operations were performed in the right eyes of rats.Reverse transcription PCR (RT-PCR) was carried out to detect the expression of NOD2 mRNA in corneal epithelium 4,8,16,24 hours after operation.Twenty-four hours after operation,the expression of NOD2 protein in rat corneas was examined by immunochemistry and immnunofluorescence technology.Also,the rat corneas were obtained for regular histopathological examination.The use and care of the animals complied with Institutional Animal Care and Use Committee Guidebook by NIH.Results All the models were made successfully.RT-PCR revealed that a fewer NOD2 mRNA were expressed on cornea in the normal control group,but the expressing levels of NOD2 mRNA were increased in the only corneal epithelial scraped group and AFK model group.Compared with only corneal epithelial scraped group,the elevated values of NOD2 mRNA expression in the AFK model group were statistically significant at 4,8,16 and 24 hours after operation (t =-0.409,-0.439,-0.534,-0.618,all at P=0.000).The histopathological examination displayed that the cornel tissue had intact structure in the normal control group,and partly corneal epithelial deficiency,slight corneal swelling and fewer neutrophil granulocytes were seen in the only corneal epithelial scraped group.However,corneal ulcer,severe corneal edema and a lot of neutrophil granulocytes were exhibited in the AFK model group.Immunochemistry and immnunofluorescence staining evidenced that weaker expression of NOD2 was visualized in the corneal epithelial and endothelial layers,and obviously enhanced staining was seen in the AFK model group.The expressing levels (absorbancy) were 0.045 ± 0.005,0.050 ± 0.005 and 0.092 ± 0.006 in the normal control group,only corneal epithelial scraped group and AFK model group,respectively,showing a significant increase in the AFK model group compared with the only corneal epithelial scraped group (t =0.042,P =0.000).Conclusions Expression of NOD2 is upregulated in the corneas with AFK,suggesting that NOD2 participates the natural defense in the initial of fungal keratitis.NOD2 may play an important role in the process of anti-fungal innate immune response in cornea.