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H. Alizadeh, S. Neelam, J. Y. Niederkorn; Role of the Mannose-Induced Acanthamoeba Protein and Acanthamoeba Plasminogen Activator as Immunogen for Mitigating Acanthamoeba Keratitis. Invest. Ophthalmol. Vis. Sci. 2007;48(13):3164.
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The mannose-induced cytopathic protein (MIP-133) and Acanthamoeba plasminogen activator (aPA) play a key role in the pathogenesis of Acanthamoeba keratitis by inducing a cytopathic effect on the corneal epithelium and stromal cells and by production of proteolytic enzymes that facilitate the invasion and penetration of trophozoites through the basement membrane. The goal of the present study was to assess whether oral immunization with MIP-133 and aPA provide protection against Acanthamoeba keratitis in a Chinese hamster animal model.
MIP-133 and aPA were isolated and purified by fast protein liquid chromatography and size exclusion chromatography. The purity of the concentrated MIP-133 and aPA was confirmed by SDS-PAGE and fibrinolytic activity, respectively. The invasiveness of the trophozoites through a synthetic basement membrane (Matrigel) was examined in vitro.
aPA is detectable in 4 pathogenic strains of Acanthamoeba spp., but is absent in 3 nonpathogenic soil isolates of Acanthamoeba spp. Pathogenic strains of Acanthamoeba spp invaded 3 fold faster through matrigel relative to nonpathogenic species. Serine protease inhibitors abrogated invasiveness of trophozoites and blocked the fibrinolytic activity of the aPA protein (P<.005). Chinese hamsters orally immunized with MIP-133 or MIP-133 + aPA displayed > 35% reduction in disease. Immunization with aPA alone did not significantly affect the course of disease. Anti-MIP-133 mucosal antibody preparations significantly inhibited the cytopathic activity of MIP-133 (P<0.05). By contrast, enteric washes from PBS or aPA-immunized animals did not inhibit cytopathic activity at any of the doses tested.
These data suggest that once the trophozoites invade the cornea, MIP-133 production is necessary to initiate corneal disease, and plays an important role in the subsequent steps of the pathogenic cascade of Acanthamoeba keratitis. Furthermore, anti-MIP-133 antibody can reduce the clinical symptoms of disease. Thus, MIP-133 protein may represent an important immunotherapeutic target for the treatment of Acanthamoeba keratitis.
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