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Laminin heterogeneity around Schlemm's canal in normal humans and glaucoma patients
T S Dietlein1, P C Jacobi, M Paulsson
1Department of Ophthalmology, Medical Faculty, University of Cologne, Germany.
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/alpha1beta1gamma1), laminin 2 (merosin/alpha2,beta1gamma1), the subunits of alpha2 (M laminin), beta1 B1laminin), gamma1 (beta2laminin) and beta2 (s laminin) and gamma2 and the associated glycoprotein nidogen.
Results:
For laminin 1, laminin 2, the subunits alpha2;, beta1, beta2, gamma1 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 gamma2 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.