The long-term objectives of this research are to characterize the extracellular matrix (ECM) components of the lamina cribrosa, the unique connective tissue that maintains the exit pathways for the axons of the optic nerve, and to determine the role these components play in the optic nerve degeneration characteristic of primary open-angle glaucoma. This research seeks to gather further evidence of individual, age-related, and/or racial differences in the lamina cribrosa that are relevant to glaucoma development. Optic nerve heads from enucleated, human eyes will be used to pursue the following Specific Aims: (1) Determine if there are differences in the connective tissue area and in the relative composition, distribution, and amount of ECM macromolecular components in the lamina cribrosa of the optic nerve head of normal blacks and whites and age-matched glaucomatous eyes; (2) characterize ultrastructurally and immunocytochemically the elastin and microfibrillar components of ECM in normal, aging, and glaucomatous human lamina cribrosa; (3) using cytochemical and immunocytochemical staining, characterize the proteoglycan composition and distribution in the ECM of the human optic nerve head as a function of age, race, and in glaucoma; (4) determine whether degradative enzymes such as metalloproteases and elastases contribute to normal aging and to the glaucomatous process in the human optic nerve head; (5) using in situ hybridization techniques, determine if the changes in the ECM components of the optic nerve head of normal, aging, and glaucomatous eyes are due to changes in the expression of specific mRNAs for ECM macromolecules and degradative enzymes; (6) and determine if mechanical and hydrostatic forces, applied in vitro to cell cultures from the lamina cribrosa, alter the gene expression, biosynthesis, and degradation of ECM macromolecules. By working on individual optic nerve heads, the normal age-related changes in the connective tissue, will be documented and compared between races, with glaucomatous tissue, and with other optic nerve degenerations. To characterize the composition, distribution, and turnover of ECM macromolecules and associated enzymes, techniques such as immmunocytochemistry, morphometry, electron microscopy, zymography, immunoprecipitation, in situ hybridization, Northern and dot blot analysis, and tissue culture will be used. These studies will lead to an understanding of the lamina cribrosa as a specialized connective tissue, help explain the biomechanical properties of the tissue and how it changes with age, and contribute to knowledge of underlying changes, and perhaps the etiology, of the glaucomatous process in the optic nerve head.
