Expression of beta ig-h3 is lower than normal in keratoconus corneas but increases with scarring

Purpose. Keratoconus is a progressive ectatic disease of the cornea. Despit e extensive clinical and laboratory investigations, its pathogenesis remain s unclear. In this study, we examined the localization of beta ig-h3, a rec ently described extracellular matrix protein in keratoconus corneas both in the absence and presence of subepithelial scarring. Methods. Two normal co rneas and central corneal buttons of 10 patients with keratoconus were exci sed during perforating keratoplasty and examined, including one case with a cute corneal hydrops. In one case, keratoconus was associated with Down syn drome. Immunodetection was done with an antipeptide antibody reacting with the N-terminal part of beta ig-h3. Results. We found decreased beta ig-h3 l evels in the basal epithelial layer and keratocytes of keratoconus corneas. In the scarred corneas, however, beta ig-h3 levels were increased in the b asal epithelial layers and in activated keratocytes at the places of scarri ng. In the cornea of the patient with Down syndrome, we found an additional beta ig-h3-positive zone in the anterior stroma. Conclusions. The decrease d levels of beta ig-h3 corneas seem to be specific for keratoconus. Conside ring the putative role of beta ig-h3 as a cellular-attachment protein, pauc ity of beta ig-h3 in the corneal stroma may lead to decreased mechanical st ability and contribute to the development of keratoconus.