Taurine, a Component of the Tear Film, Exacerbates the Pathogenic Mechanisms of Acanthamoeba castellanii in the Ex Vivo Amoebic Keratitis Model

Abstract

Acanthamoeba spp. is the etiological agent of amoebic keratitis. In this study, the effect of taurine in physiological concentrations in tears (195 μM) on trophozoites of Acanthamoeba castellanii through the ex vivo amoebic keratitis model was evaluated. Trophozoites were coincubated with the Syrian golden hamster cornea (Mesocricetus auratus) for 3 and 6 h. Group 1: Control (−). Corneas coincubated with amoebic culture medium and taurine. Group 2: Control (+). Corneas coincubated with trophozoites without taurine. Group 3: Corneas coincubated with taurine 15 min before adding trophozoites. Group 4: Trophozoites coincubated 15 min with taurine before placing them on the cornea. Group 5: Corneas coincubated for 15 min with trophozoites; subsequently, taurine was added. Results are similar for both times, as evaluated by scanning electron microscopy. As expected, in the corneas of Group 1, no alterations were observed in the corneal epithelium. In the corneas of Group 2, few adhered trophozoites were observed on the corneal surface initiating migrations through cell junctions as previously described; however, in corneas of Groups 3, 4 and 5, abundant trophozoites were observed, penetrating through different corneal cell areas, emitting food cups and destabilizing corneal surface in areas far from cell junctions. Significant differences were confirmed in trophozoites adherence coincubated with taurine (p < 0.05). Taurine does not prevent the adhesion and invasion of the amoebae, nor does it favor its detachment once these have adhered to the cornea, suggesting that taurine in the physiological concentrations found in tears stimulates pathogenic mechanisms of A. castellanii.

Staurosporine as a potential treatment for Acanthamoeba keratitis using mouse cornea as an ex vivo model

“…In this sense, Omaña-Molina et al, (2013) demonstrated that A. castellanii and A. polyphaga invasion and disruption of corneal epithelium in the hamster model is performed by the penetration of the amoebae through cell junctions either by the action of proteases and/or a mechanical effect exerted by trophozoites, suggesting that the contact-dependent activity is an important pathogenic mechanism of these strains of Acanthamoeba [12]. Moreover, in a previous study Omaña-Molina et al, (2010) cocultivated A. castellanii trophozoites with human corneas and reported mechanisms of pathogenicity of amoebic infections were very similar to the previous study using a hamster model and our ndings using a mouse model, which validate these animal models for the study of the pathogenesis of AK [11,13,31].…”

“…A total of 12 pathogen-free male BALB/c (Mus musculus) mice were used, with an average age of 21 to 28 days and an average body weight of 35 g. Experiments were based on protocol previously described in hamster cornea (Mesocricetus auratus) [11][12][13], and were approved by Research Ethics and Animal Welfare Committee of the University of La Laguna, included in the project known as Evaluation of the in vivo amoebicidal activity of eye drops containing active ingredients administered via the ocular route, with the reference number CEIBA2021-3074.…”

“…Rabbits, hamsters and mice were used as models for in vivo assay of Acanthamoeba Keratitis [8,9]. To the best of our knowledge, only the hamster cornea has been used as an ex vivo model for Acanthamoeba keratitis [10][11][12][13]. The aim of the present study was to evaluate Staurosporine as potential treatment for Acanthamoeba keratitis using mouse cornea as an ex vivo model and to investigate its model of action by comparative proteomic analysis.…”