Macular degeneration insight identifies promising drugs to prevent vision loss
by David Tenenbaum
In a study published this week in the Proceedings of the National Academy of Sciences, a University of Wisconsin-Madison research team pinpoints how immune abnormalities beneath the retina result in macular degeneration, a common condition that often causes blindness.
Aparna Lakkaraju, an assistant professor of ophthalmology and visual sciences, focused on two protective mechanisms that are compromised during the gradual onset of macular degeneration, which degrades and can destroy the central vision needed to read and recognize faces.
In tests in a mouse model of macular degeneration, drugs that are already on the market prevented damage to the cells that sustain the light-sensitive cells in the eyes.
“These studies raise the possibility of treatments that could slow or prevent macular degeneration,” says Lakkaraju.
Macular degeneration destroys central vision in about 2 million Americans, mainly among the elderly, and is largely untreatable.
Although macular degeneration eventually damages or kills the light-sensitive rods and cones, Lakkaraju explains that it starts with injury to the retinal pigment epithelium (RPE). The RPE, a single layer of cells beneath the rods and cones at the back of the eye, performs many functions essential for healthy vision. The damage starts with a disturbance of immune proteins called complement, which normally kill disease-causing organisms by boring holes in their cell membranes.
“The light-detecting cells in the retina are totally dependent on the RPE for survival,” says Lakkaraju, “but the RPE cells are not replaced through the lifespan. So we asked, ‘What are the innate protective mechanisms that keep the RPE healthy, and how do they go awry in macular degeneration?'”
In a study performed with colleagues Li Xuan Tan and Kimberly Toops, Lakkaraju focused on two protective mechanisms: the protein CD59, which regulates complement activity when attached to the outside of RPE cells; and lysosomes, spherical structures that plug pores created by the complement attack (a function that Lakkaraju’s team first detected in the RPE)…….
Source: Medical Xpress