Keratocyte loss in corneal infection through apoptosis: a histologic study of 59 casesReportar como inadecuado

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BMC Ophthalmology

, 4:16

First Online: 24 December 2004Received: 26 April 2004Accepted: 24 December 2004


BackgroundKeratocyte loss by apoptosis following epithelial debridement is a well-recognized entity. In a study of corneal buttons obtained from patients of corneal ulcer undergoing therapeutic keratoplasty, we observed loss of keratocytes in the normal appearing corneal stroma, surrounding the zone of inflammation. Based on these observations, we hypothesized that the cell loss in the inflammatory free zone of corneal stroma is by apoptosis that could possibly be a non-specific host response, independent of the nature of infectious agent.

MethodsTo test our hypothesis, in this study, we performed Terminal deoxyribonucleotidyl transferase-mediated d-Uridine 5- triphosphate Nick End Labelling TUNEL staining on 59 corneal buttons from patients diagnosed as bacterial, fungal, viral and Acanthamoeba keratitis. The corneal sections were reviewed for morphologic changes in the epithelium, stroma, type, degree and depth of inflammation, loss of keratocytes in the surrounding stroma posterior or peripheral. TUNEL positivity was evaluated in the corneal sections, both in the zone of inflammation as well as the surrounding stroma. A correlation was attempted between the keratocyte loss, histologic, microbiologic and clinical features.

ResultsThe corneal tissues were from 59 patients aged between 16 years and 85 years mean 46 years and included fungal 22, viral 15, bacterial 14 and Acanthamoeba 8 keratitis. The morphological changes in corneal tissues noted were: epithelial ulceration 52, 88.1%, destruction of Bowman-s layer 58, 99%, mild to moderate 28; 47.5% to severe inflammation 31; 52.5%. Morphologic evidence of disappearance or reduced number of keratocytic nuclei in the corneal stroma was noted in 49 83% cases; while the TUNEL positive brown cells were identified in all cases 53-54 98%, including cases of fungal 19, bacterial 14, viral 13, and Acanthamoeba keratitis. TUNEL staining was located mostly in the deeper stroma and in few cases the peripheral stroma. TUNEL positivity was also noted with the polymorphonuclear infiltrates and in few epithelial cells 10 of 59, 17% cases, more with viral infections 6-10; 60%.

ConclusionsWe report apoptotic cell death of keratocytes in the corneal stroma in infectious keratitis, a phenomenon independent of type of infectious agent. The inflammatory cells in the zone of inflammation also show evidence of apoptotic cell death. It could be speculated that the infective process possibly triggers keratocyte loss of the surrounding stroma by apoptosis, which could possibly be a protective phenomenon. It also suggests that necrotic cell death and apoptotic cell deaths could occur simultaneously in infective conditions of the cornea.

Keywordsinfectious keratitis apoptosis keratocytes TUNEL stain Electronic supplementary materialThe online version of this article doi:10.1186-1471-2415-4-16 contains supplementary material, which is available to authorized users.

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Autor: Geeta K Vemuganti - Kishore Reddy - Ghazala Iftekhar - Prashant Garg - Savitri Sharma


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