Purpose: To examine changes of select reduction-oxidation (redox) sensitive proteins from human donor retinal pigment epithelium (RPE) at four stages of age-related macular degeneration (AMD). Design: Experimental study. Methods: Human donor eyes were obtained from the Minnesota Lions Eye Bank and graded using the Minnesota Grading System (MGS) into four stages that correspond to stages defined by the age-related eye disease study (AREDS). Protein content in RPE homogenates was measured using Western immunoblotting with protein-specific antibodies. Results: The content of several antioxidant enzymes and specific proteins that facilitate refolding or degradation of oxidatively damaged proteins increased significantly in MGS stage 3. These proteins are involved in the primary (copper-zinc superoxide dismutase [CuZnSOD], manganese superoxide dismutase [MnSOD], and catalase) and secondary (heat shock protein [HSP] 27, HSP 90, and proteasome) defense against oxidative damage. Additionally, the insulin pro-survival receptor exhibited disease-related upregulation. Conclusions: The pattern of protein changes identified in human donor tissue graded using the MGS support the role of oxidative mechanisms in the pathogenesis and progression of AMD. The MGS uses nearly identical clinical definitions and grading criteria of AMD that are used in the AREDS, so our results apply to clinical and epidemiologic studies using similar definitions. Results from our protein analysis of human donor tissue helps to explain altered oxidative stress regulation and cell-survival pathways that occur in progressive stages of AMD.
Bibliographical noteFunding Information:
This Study was Supported by the National Institute on Aging Grant No. AG025392 (T.W.O.), National Eye Institute, Grant EY014176, Bethesda, Maryland, (D.A.F.), Minnesota Lions Macular Degeneration Center, Minneapolis, Minnesota and Minnesota Lions Eye Bank, and an unrestricted grant to from Research to Prevent Blindness Foundation, Inc, New York, New York. The authors indicate no financial conflict of interest. Involved in conduct and design of study (A.D., D.A.F., T.W.O.); collection, management, analysis, and interpretation of the data (A.D., C.L.N., X.F., D.A.F., T.W.O.); and preparation, review, or approval of the manuscript (A.D., C.L.N., X.F., D.A.F., T.W.O.).