Abstract
Abstract: :
Purpose: Endothelin (ET) A and B receptors are targets of ET-1 which is a potent mitogen for endothelial cells and an inducer of angiogenesis. ET-1 has been detected in newly formed pathologic blood vessels in human corneas. We therefore analyzed mRNA and protein expression of ET-A and ET-B receptors in normal non-vascularized and vascularized human corneas. Methods: Using in situ-hybridisation, indirect immunohistochemistry and double immunofluorescence (with antibodies against CD 31), we investigated ET-A and ET-B receptor mRNA and protein expression in normal corneas, in corneas with keratoconus and Fuchs' endothelial dystrophy, and in vascularized corneas secondary to graft rejection, trauma and herpetic keratitis. Results: Normal human corneas displayed ET-A and ET-B receptor mRNA and protein expression in the basal layers of the corneal epithelium and corneal endothelium. Whereas ET-A receptor was found predominantly in the cytoplasm of epithelial cells, keratocytes and endothelial cells, ET-B receptor showed a nuclear staining pattern in epithelial and endothelial cells. The keratocytes showed almost no reactivity for ET-B receptors. Expression of ET-A and ET-B receptor mRNA and protein was more pronounced in the epithelium of vascularized compared to non-vascularized human corneas. The keratocytes of vascularized corneas showed a significantly increased ET-B receptor expression. In addition, ET-A and ET-B receptor mRNA and protein could be localized to endothelial cells of newly formed vessels by double labelling with anti-CD 31 antibodies. Conclusion: Expression of ET-A and ET-B receptors in endothelial cells of newly formed pathologic human corneal blood vessel as well as the upregulation of both receptors in the epithelium and ET-B in stromal keratocytes of vascularized corneas indicate involvement of ET-receptors in human corneal neovascularisation. Thus, ET-A and ET-B receptors may represent additional targets for an angiostatic therapy against corneal neovascularisation using well established receptor antagonists.
Keywords: 434 immunohistochemistry • 371 cornea: endothelium • 372 cornea: epithelium