Translationally Controlled Tumour Protein (TCTP) is present in human cornea and increases in herpetic keratitis
BACKGROUND Herpes simplex virus (HSV-1) stromal keratitis is an immune-mediated disease. Recently, it has been shown that infection of cells with HSV-1 induces apoptosis. In this study we investigated the presence of apoptotic cell death in keratectomy specimens from patients with HSV-1 stromal keratitis. PATIENTS AND METHODS Keratectomy specimens from six patients with HSV-1 non-necrotizing stromal keratitis were chosen and compared to healthy corneas. Paraffin sections were analyzed histologically and cryosections were studied by the immunoperoxidase technique for the presence of HSV-1, Fas and FasLigand (FasL) antigens. Apoptosis was assessed by TUNEL assay (TdT-mediated dUTP nick-end labeling). RESULTS In healthy corneas, Fas was detected in the epithelium, keratocytes and endothelium; FasL was present in the epithelium and endothelium; TUNEL-positive cells were only found in the superficial epithelial cells. In contrast, inflammatory cells and scars were found in all HSV-diseased corneas; HSV-1 antigen was detected in only one specimen. Cells within inflammatory infiltrations and epithelium were apoptotic. Fas was detected in all corneal cell layers and inflammatory cells. FasL was restricted to areas of inflammation. CONCLUSIONS The data suggest that apoptosis plays a role in the pathogenesis of HSV keratitis. The Fas-FasL system appears to be involved in the induction of apoptosis. Apoptosis could be involved in the depletion of inflammatory cells in the cornea and may limit the extension of viral replication to the eye.