Induction of morphological and electrophysiological changes in hamster cornea after in vitro interaction with trophozoites of Acanthamoeba spp.
Acanthamoeba castellani and Acanthamoeba polyphaga are free-living amebae that cause keratitis and granulomatous encephalitis in humans. We have analyzed the early morphological and electrophysiological changes occurring during the in vitro interaction of cultured amebae with intact or physically damaged corneas obtained from hamsters. Both species of Acanthamoeba produced similar cytopathic changes, as seen by light microscopy and scanning electron microscopy. After adhesion to the epithelial surface, trophozoites formed clumps and migrated toward the cell borders, causing the separation of adjacent cells at 1 h of coculture. At later stages (2 to 4 h), some amebae were found under desquamating epithelial cells whereas others were seen associated with damaged cells or forming amebostome-like structures to ingest detached epithelial cells. Control corneas incubated in culture medium conditioned with amebae showed a cytoplasmic vacuolization and blurring of the epithelial-stromal junction. The early stages of corneal epithelial damage caused by amebae were also analyzed by measuring the transepithelial resistance changes in corneas mounted in Ussing chambers. Both species of Acanthamoeba caused a rapid decrease in electrical resistance. The present observations demonstrate that under in vitro conditions, Acanthamoeba trophozoites rapidly cause significant damage to the corneal epithelium. Furthermore, in our experimental model, previous physical damage to the corneas was not a prerequisite for the development of amebic corneal ulcerations.
Omaña-Molina
Maritza
M
Department of Experimental Pathology, Center for Research and Advanced Studies, Mexico City, Mexico.
Navarro-García
Fernando
F
González-Robles
Arturo
A
Serrano-Luna
José de Jesús
Jde J
Campos-Rodríguez
Rafael
R
Martínez-Palomo
Adolfo
A
Tsutsumi
Víctor
V
Shibayama
Mineko
M
D000048:Acanthamoeba / Q000145:classification / Q000254:growth & development / Q000472:pathogenicity*; D015823:Acanthamoeba Keratitis / Q000473:pathology*; D000818:Animals; D003315:Cornea / Q000469:parasitology / Q000473:pathology*; D006224:Cricetinae; D004195:Disease Models, Animal; D004594:Electrophysiology; D019573:Epithelium, Corneal / Q000469:parasitology / Q000473:pathology; D006801:Humans; D008855:Microscopy, Electron, Scanning