Scientists have good news for patients who suffer from currently untreatable dry age-related macular degeneration (dry AMD). In a new study, researchers identified a potential target for future therapies to slow the progression of the blinding condition. Published in Investigative Ophthalmology & Visual Science (IOVS), the findings indicate that treatments currently used for other conditions could also work for dry AMD.
The paper, "Protective Effects of Anti-Placental Growth Factor Antibody Against Light-Induced Retinal Damage in Mice," brings to light the effect of a known protein, placental growth factor (PlGF), on the development of dry AMD. PlGF had previously been implicated in the progression of a related disease known as wet AMD.
"Currently, blocking PlGF in wet AMD has a therapeutic effect," says author Hideaki Hara, PhD, of Gifu Pharmaceutical University, Department of Biofunctional Evaluation. "In our study, we wanted to learn if PlGF could be a useful therapeutic target for dry AMD."
Earlier in vitro studies by the authors showed that injecting PlGF into retinal cells -- the cells at the back of the eye responsible for sight -- reduced light-induced damage. In this work, the authors evaluated how mice retina responded to injection of PlGF before and after exposure to intense light, a procedure that produces dry AMD-like conditions. Surprisingly, the new in vivo mouse studies contradicted the previous results.
"In the present study, we thought that treatment with PlGF would show a protective effect against light-induced retinal degeneration," explains Hara. "Instead, PlGF aggravated the degeneration."
With PlGF seeming to make things worse, the authors then tested anti-PlGF, an antibody that binds PlGF and prevents it from acting. "Anti-PlGF antibody treatment protected against retinal degeneration induced by light exposure. Therefore, our results indicate that an anti-PlGF antibody can become a therapeutic agent in minimizing light-induced degeneration," says Hara.
Fortunately, an existing treatment for wet AMD known as aflibercept already acts as an anti-PlGF antibody. Hara and his team "think there is a very great likelihood that aflibercept shows efficacy in dry AMD." Using an existing drug in clinical trials could shave years off the time needed to determine if an anti-PlGF treatment could address dry AMD, an encouraging prospect for those suffering from the slow, currently untreatable vision loss resulting from the condition.
The ARVO peer-reviewed journal Investigative Ophthalmology & Visual Science (IOVS) publishes results from original hypothesis-based clinical and laboratory research studies, as well as Reviews, Perspectives, and special issues. IOVS ranks No. 1 among 58 ophthalmology journals for number of citations and its 2014 Impact Factor places it at No. 8. The journal is online-only (http://iovs.