Immunohistochemistry of proteoglycans in human lamina cribrosa

Proteoglycans are macromolecular components of connective tissue, which are believed to have an important role in the organization of other extracellular matrix components and in the hydration and rigidity of tissue. Using antibodies to the heparan sulfate-, dermatan sulfate-, and keratan sulfate-proteoglycans core proteins, we used indirect immunofluorescence to determine the presence of these core proteins and to characterized their distribution in the lamina cribrosa of healthy human eyes of various ages. Findings with heparan sulfate-proteoglycan core proteins support the multilayered organization of basement membranes in the lamina cribrosa as proposed in previous reports. Dermatan sulfate-proteoglycan core protein results indicate colocalization with fibrillar collagen. Application of monoclonal antibodies to the glycosaminoglycan side chain disclosed an increasing predominance of chondroitin-4-sulfate over chondroitin-6-sulfate with age. This may indicate a decreasing water-holding capacity of the cribriform plates and suggest a decreasing ability to withstand pressure. This study attempts to identify the core proteins of proteoglycans in human lamina cribrosa and serves as a basis for study of glaucomatous eyes.