Laminin Heterogeneity around Schlemm’s Canal in Normal Humans and Glaucoma Patients

Abstract

Background: The laminins play an important role in cell attachment to the extracellular matrix. This study was undertaken in order to investigate and to compare the presence of several laminin chains and isoforms in normal and glaucomatous trabecular meshwork. Methods: Fresh-frozen trabeculectomy specimens from glaucoma patients and trabecular meshwork from human donor eyes were included for immunohistochemistry. We used antibodies against laminin 1 (EHS-laminin/α1β1γ1), laminin 2 (merosin/α2β1γ1), the subunits α2 (M laminin), β1 (B1 laminin), γ1 (B2 laminin), β2 (s laminin) and γ2 and the laminin-associated glycoprotein nidogen. Results: For laminin 1, laminin 2, the subunits α2, β1, β2, γ1 and nidogen, the immunoreactivity of the juxtacanalicular zone underneath the inner wall of Schlemm’s canal was always stronger than of the uveal and corneoscleral trabecular meshwork. Staining for laminin chain γ2 could not be demonstrated in the outflow structures. Pattern and intensity of labelling for the laminins were not different between normal and glaucomatous eyes. Discussion: Heterogeneity of the laminins suggests structural complexity of the juxtacanalicular region. However, the presence of laminin around Schlemm’s canal seems to be unaffected by glaucoma and by age. This might indicate maintenance of basement membrane stability in the trabecular meshwork for life.