Macular degeneration is the leading cause in partial or complete blindness of adults over 60 in the United States. The disease targets the macula in the eyes which in large part is what enables us to perceive the fine detail that allows us do things like reading and driving.
A new study, published in the journal Cell Metabolism on April 2 2013, involved the study of macrophages from old mice and humans with macular degeneration. Macrophages, white blood cells that deconstruct cholesterol, have been found in higher than normal concentration in subjects with macular degeneration. In previous studies, this cellular build up has been shown to possibly cause abnormal blood vessels to grow in the eye resulting in bleeding, scarring and blindness. In the new study, subjects were found to have low levels of a protein that removes cholesterol from cells called ABCA1.
Scientists tested two types of cholesterol regulating drugs via injection and eye drop application with mice. Both the eye drop applied Liver X Receptor (LXR) and the injected microRNA-33 inhibitor increased levels of ABCA1 in the test subjects and improved cholesterol transportation in the macrophages. As a result, new ocular blood vessels were reduced. The less invasive eye drop application showed promise of reduced side effects according to the scientists.
The researchers are optimistic about the early results with mice and believe that the new understanding of cholesterol’s role in causing the growth of ocular blood vessels is a step in the right direction. The findings and future research may allow researchers to modify existing drugs to deliver treatment to the eyes stated Dr. Rajendra Apte, a professor of ophthalmology and visual sciences at the Washington University School of Medicine in St. Louis.
“Clearly this research is still at an early stage but it will be exciting to watch how it progresses and at some point cholesterol-lowering eye drops may become part of a growing army of treatments for sight-threatening eye conditions,” Clara Eaglen, a spokesperson for the U.K. eye charity RNIB.
Study: Impaired Cholesterol Efflux in Senescent Macrophages Promotes Age-Related Macular Degeneration by Sene et. al. Cell Metabolism, Volume 17, Issue 4, 549-561, 2 April 2013 http://www.cell.com/cell-metabolism/abstract/S1550-4131%2813%2900113-7