Immunity may play role in eye disease

Changes in how genes in the immune system function may result in age-related macular degeneration, a leading cause of blindness, U.S. researchers say. Age-related macular degeneration damages the light-sensitive cells of the macula, the central part of the retina that allows us to see fine visual detail. As the disease progresses, patients encounter great difficulty reading, driving, or performing hobbies and tasks that require hand-eye coordination. "Our findings are epigenetic in nature, meaning that the underlying DNA is normal but gene expression has been modified, likely by environmental factors, in an adverse way," Dr. Robert Nussenblatt, chief of the National Eye Institute Laboratory of Immunology, part of the National Institutes of Health, said in a statement. "Environmental factors associated with age-related macular degeneration include smoking, diet, and aging. This is the first epigenetic study revealing the molecular mechanisms for any eye disease." The study by Nussenblatt and colleagues at the National Heart, Lung, and Blood Institute; the National Center for Complementary and Alternative Medicine; the University of Melbourne in Australia; and Oregon Health and Science University, identified decreased levels of DNA methylation, a chemical reaction that switches off genes, on the interleukin-17 receptor C gene. The lack of DNA methylation led to increased gene activity and, in turn, increased levels of interleukin-17 receptor C gene proteins in patients with age-related macular degeneration. Interleukin-17 receptor C gene is a protein that promotes immune responses to infections, such as fungal attacks, the study found. Their findings were to be published in Cell Reports.