Biomarker Shows Potential for Early Detection of AMD

A biomarker has been discovered with strong potential for both early detection and preventive treatment of neovascular (or wet-type), age-related macular degeneration (AMD) in humans.

Called CCR3, the marker for AMD was used in animal experiments--quantum dots attached to anti-CCR3 antibodies were injected into the eyes of living mice. They bound to CCR3 on the surface of abnormal vessels making them visible through conventional means, even before they had penetrated the retina.

Neovascular macular degeneration is caused by choroidal neovascularization (CNV)--the invasive growth of new blood vessels in the thin vascular layer that provides nourishment and oxygen to the eye. Central vision loss occurs when these abnormal blood vessels invade the retina, the light-sensitive tissue that lines the inner surface of the eyeball.

CCR3 not only provides a unique genetic signature for CNV, but also it actively promotes the growth of these abnormal blood vessels in the eye. Thus, the same anti-CCR3 antibodies used to detect CNV could be useful as a clinical treatment to prevent macular degeneration.

A team, led by Dr. Jayakrishna Ambati, professor of physiology, professor and vice-chair of ophthalmology and visual sciences at the University of Kentucky (Lexington, KY, USA), discovered the biological marker CCR3A, which is associated with AMD, the leading cause of blindness in older adult men and women. The investigators discovered that CCR3--a molecule also implicated in inflammatory processes--is expressed on the surface of CNV vessels in humans but is absent from normal vascular tissue.

Dr. Ambati commented, "With CCR3, we have for the first time found a unique molecular signature for the disease. This brings us closer than we have ever been to developing a clinical diagnostic tool to discover and treat the disease early, before vision is lost."

The Kentucky University team's work was published in the June 14, 2009 edition of Nature.

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