Abstract
Purpose: :
To investigate the localization of glycosaminoglycans (GAGs) in the human macula using immunohistochemistry and fluorescence microscopy.
Methods: :
Postmortem human eye tissue was obtained, following removal of the cornea for transplantation, from consenting eye donors. Macular tissue was fixed in 4% paraformaldehyde prior to freezing, and serial sections were cut. These were probed with a series of antibodies raised against GAG chains; primary antibodies were detected using fluorescently labelled secondary antibodies. In some cases, tissue sections were digested with GAG-degrading enzymes prior to application of the primary antibodies.
Results: :
GAG chains demonstrated differential localization within human macular tissue. Within the neurosensory retina, chondroitin sulfate (CS) was seen predominantly in the interphotoreceptor matrix, and dermatan sulfate (DS) mainly in the ganglion cell layer. Heparan sulfate (HS) and hyaluronan (HA) were observed throughout the neurosensory retina, and HS displayed segregation by sulfation pattern. Minimal staining for keratan sulfate (KS) was found in the neurosensory retina. In general, GAGs with low levels of sulfation (including HA) were observed at the internal limiting membrane. HS, DS and KS were present to varying degrees in the retinal pigment epithelium, Bruch's membrane and in the walls of choroidal blood vessels.
Conclusions: :
GAG chains display differential localization in the human macula according to both GAG chain type and degree of sulfation. This has important implications for understanding eye development and disease, and for planning novel therapeutic strategies.
Keywords: immunohistochemistry • proteoglycans/glycosaminoglycans • macula/fovea