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Acanthamoebae bind to rabbit corneal epithelium in vitro
1New England Eye Center, Boston, Massachusetts.
Purpose:
Selection of an appropriate animal model is crucial for the investigation of the pathogenesis of Acanthamoeba keratitis. To this end, it has been reported that fluorescein isothiocyanate (FITC)-labeled Acanthamoeba castellanii bind to human, pig, and hamster corneas, but not to rabbit corneas in organ culture. However, 35S-labeled A. polyphaga and A. culbertsoni have been found to bind to rabbit corneal epithelium grown in tissue culture. The purpose of the current study was to establish whether A. castellanii bind to rabbit corneal epithelium in organ culture.
Methods:
Two different adhesion assays were used to determine whether 35S-labeled and FITC-labeled A. castellanii bind to epithelium of corneal buttons in vitro and, if so, whether the binding is temperature-dependent, enhanced by injury, and inhibited by specific saccharides. Ameba binding to rabbit corneal epithelium was also evaluated by scanning electron microscopy. The binding of A. castellanii to corneal epithelium of three different species (human, pig, and rabbit) was compared.
Results:
Both 35S-labeled as well as FITC-labeled parasites were found to bind to epithelium of rabbit corneal buttons in vitro. Although the parasites bound avidly to the corneas at 25 degrees C and 35 degrees C, little binding was observed at 4 degrees C. Injury enhanced the binding. Methyl alpha-D-mannopyranoside, but not other saccharides (alpha-L-fucose and beta-galactose), inhibited binding of the parasites to the epithelium of rabbit corneas. By scanning EM, A. castellanii were found to adhere, invade, and penetrate the epithelium of rabbit corneas. Compared with rabbit corneas, ameba binding to pig, and human corneas was only 1.2 and 1.4 times higher, respectively.
Conclusions:
Rabbit animal model may prove useful for investigation of the molecular mechanisms that mediate adhesion of Acanthamoeba to corneal epithelium.
Insights
Acanthamoeba castellanii binds to rabbit corneas in vitro, suggesting the rabbit model is useful for studying Acanthamoeba keratitis. Binding is temperature-dependent and enhanced by injury.
Area of Science:
- Ophthalmology
- Microbiology
- Cell Biology
Background:
- Investigating Acanthamoeba keratitis pathogenesis requires suitable animal models.
- Previous studies showed conflicting results regarding Acanthamoeba binding to rabbit corneas.
Purpose of the Study:
- To determine if Acanthamoeba castellanii binds to rabbit corneal epithelium in organ culture.
- To assess factors influencing this binding, including temperature, injury, and specific saccharides.
Main Methods:
- Utilized 35S-labeled and FITC-labeled Acanthamoeba castellanii in adhesion assays.
- Evaluated binding to rabbit, pig, and human corneal buttons in vitro.
- Employed scanning electron microscopy and tested inhibition by specific saccharides.
Main Results:
- Acanthamoeba castellanii demonstrated significant binding to rabbit corneal epithelium in vitro.
- Binding was temperature-dependent (optimal at 25°C and 35°C) and enhanced by corneal injury.
- Methyl alpha-D-mannopyranoside inhibited binding, indicating specific molecular interactions.
Conclusions:
- The rabbit animal model is suitable for studying Acanthamoeba adhesion to corneal epithelium.
- Findings support the use of rabbits to investigate the molecular mechanisms of Acanthamoeba keratitis.