The Preliminary Study Of The Pathogenesis Of Fungal Keratitis In Mice With Different Immunocompetency

Purpose:Preliminary study found that adaptive immune response played an important role in the pathogenensis of fungal keratitis with immunocompetent mice. This study was to further explore the role of the immune response in the pathogenensis of fungal keratitis with the immunodeficient mice.Methods:The normal Balb/c mice, Nude mice (T cell defect) and SCID (T、B cell defect) mice of6-8weeks on Balb/c background were infected with Candida albicans spores or Aspergillus fumigatus spores of1.0μl at a concentration of1×108CFU/ml to induce Candida albicans keratitis (CaK) or Aspergillus fumigatus keratitis (AfK) by cornea intrastromal injection. The disease was continuous monitored using slit lamp, according the depth and the lesions range of corneal disease, and surface regularity to clinically evaluate. At1,3,7and14day of post infection, murine eyes were enucleated for histological examination, and PAS and HE staining were used to observe the growth of fungal hyphae and inflammatory cell infiltration in murine cornea tissue. The number of live-fungi in corneal tissue was detected with CFU. The production of IL17, IFNγ and IL10in plasma and corneal tissue homogenate were evaluated by ELISA. The CD19+-IL10+double positive cells in murine spleen of each group were analyzed using Flow cytometry.Result:Compared to the corneas of normal saline control group in Balb/c mice (Balb/c-Sham) or SCID mice (SCID-Sham) with very mild inflammation, Candida albicans or Aspergillus fumigatus infection to the corneas occurred typical fungal keratitis, both average disease scores reached the peak at5day, then gradually decreased; A large number of fungal hyphae and inflammatory cells infiltration were found in the corneal tissue at1day and3day with histology and CFU examination; at14day there were less fungus in corneal tissue and inflammation tended to heal. Compared to the typical FK in Balb/c mice or SCID mice, under the same condition Nude mice couldn’t induce the typical CaKand AfK; it only showed mild change (similar to the saline control group of normal Balb/c mice), the cornea was restored to normal at7day; the number of live-fungi in its corneal tissue significantly had reduced at1day, at5days there were less fungus in corneal tissue. The IL17and IFNγ in plasma and corneal homogenates of Balb/c-Sham and SCID-Sham maintained at a lower level without marked change; otherwise, The IL17in the infection group of Balb/c mice (Balb/c-CaK/AfK) and SCID mice (SCID-CaK/AfK) increased in the FK early time, and then decreased, while IFNγ increased in the FK midanaphase. Compared to Balb/c-CaK/AfK and SCID-CaK/AfK, IL17and IFNγ in plasma and corneal homogenates of Nude mice infection group (Nude-CaK/AfK) retained at a lower level without significant change; while IL10increased at a high level in the early time, and then decreased, which was secreted by CD19+cells of murine spleen with Flow cytometry analysis; however, in Balb/c-CaK/AfK group IL10increased at a low level in the early time, and then decreased, in SCID-CaK/AfK group IL10didn’t detected.Conclusion:Different cytokines in different anmials induced by FK displayed:IL17produced by innate immune cells plays an important role in the induction of fungal keratitis; IL10secreted by B cells inhibits the induction of fungal keratitis in the early time; IFNγ produced by innate immune cells plays an important role in the turnover of fungal keratitis. The change of key cytokines in the pathogenesis of Candida albicans keratitis or Aspergillus fumigatus keratitis is probably similar.