The overall goal of this proposal is to better understand impaired phospholipid metabolism in the trabecular meshwork (TM) tissue in glaucoma. The term phospholipid (PL) here refers to primarily three classes of lipids: phosphatidylcholine (PC), phosphatidylserine (PS), phosphatidylethanolamine (PE). A better understanding of PL metabolism in the anterior eye chamber will provide insight into glaucoma pathology and facilitate the development of new, disease-modifying intervention strategies. Our long-term goal is to develop better intervention strategies for glaucoma by understanding the pathological changes in metabolism, and in particular PL metabolism, in the glaucomatous anterior chamber. The absence of a comprehensive knowledge of PL changes in diseased compared to healthy aqueous humor (AH) or TM represents a critical barrier to progress in treating and preventing glaucoma. The proposed research is based on our extensive preliminary studies performed over the past seven years. We discovered a substantial decrease in PS and a general increase in PE lipid species in glaucomatous TM compared to controls. This has followed rigorous analyses of levels and activity of enzymes in a comprehensive and unbiased manner, demonstrating their alteration at critical branch points. Thus, we propose to comprehensively investigate all PL interconversion enzymes in an unbiased manner. We also found vastly different fold changes differing only slightly with respect to acyl-chain length (or structural features) between control and glaucomatous TM or AH suggesting that the functions of transport proteins are potentially aberrant in glaucomatous TM. We propose to investigate selected PL transport proteins in glaucomatous TM tissue. Pathologic TM tissue consistently demonstrates altered biophysical properties, for example an elevated elastic modulus. Our central hypothesis is that phospholipid metabolism is impaired in glaucoma, affecting biophysical properties of the trabecular meshwork and contributing to its pathophysiology.
In Aim 1 we will test whether PL interconversion enzymes are altered in glaucoma, In Aim 2 we will evaluate whether PL transport proteins are altered in glaucoma, and finally in Aim 3 we will determine whether restoring specific PLs that become deficient in the diseased state can improve the biophysical properties of glaucomatous TM. We will also evaluate correlation of biophysical properties with IOP lowering in murine models. We will use routine (Western blot, immunosorbent assays) and innovative methods analytical techniques such as kinetic histochemistry employing imaging mass spectrometry. The proposal also has brought forth a conceptual innovation that is PL metabolism impairment in TM in glaucoma. The expected outcome of the proposed research is the identification of aberrations in specific enzymes of PL metabolizing pathways and in PL molecules that dysregulate biophysical properties of TM. These new insights will have an important impact on developing novel glaucoma therapies.
The goal of this work is to better understand the impaired phospholipid metabolism in the glaucomatous trabecular meshwork (TM) tissue. Proposal will evaluate the enzymatic activities in the phospholipid metabolism pathways. Successful completion of this research will yield new insight into the phospholipid metabolic impairment in the TM and their possible potential modulation in the treatment of glaucoma.
