Patients with any stage of age-related macular degeneration (AMD) carry signs of the disease in their blood that may be found through special laboratory tests, according to a new study led by HMS researchers at Massachusetts Eye and Ear.
The study, published online in Ophthalmology, describes a new technique known as “metabolomics,” which can identify blood profiles associated with AMD—the leading cause of adult blindness in developed countries—and its level of severity.
These potential lipid biomarkers in human blood plasma may lead to earlier diagnosis, better prognostic information and more precise treatment of patients with AMD, as well as possible new targets for AMD treatment.
“With metabolomics, we can identify blood profiles associated with AMD and its severity through laboratory testing,” said co-senior author Joan Miller, the HMS David Glendenning Cogan Professor of Ophthalmology and chief of the Department of Ophthalmology at Mass. Eye and Ear and Massachusetts General Hospital.
“Because the signs and symptoms of early stage AMD are very subtle, with visual symptoms only becoming apparent at more advanced stages of the disease, identification of biomarkers in human blood plasma may allow us to better understand the early to intermediate stages of AMD so we may intervene sooner, and ultimately provide better care,” he said.
AMD is the leading cause of blindness in people over age 50 in developed countries, and its prevalence is expected to increase along with the global aging of populations in these countries.
While AMD has recognized genetic and lifestyle risk factors, including diet and smoking status, the field currently lacks reliable measures to identify patients who may be at risk of developing AMD and those who may progress to the advanced, blinding forms of the disease.
“The study utilized a technique known as metabolomics, or the study of the tiny particles called metabolites, in our body that reflect our genes and environment,” explained first author Ines Lains, HMS research fellow in ophthalmology at Mass. Eye and Ear.
“The metabolome—the set of metabolites present in an individual—is thought to closely represent the true functional state of complex diseases. This is why we used it to test 90 blood samples obtained from study participants with all stages of AMD (30 with early-stage disease, 30 with intermediate-stage and 30 with late-stage) and 30 samples from patients without AMD,” Lains said.
The metabolomics data analysis was performed in collaboration with Jessica Lasky Su, HMS associate professor of medicine at Brigham and Women’s Hospital, and colleagues at the hospital’s Channing Division of Network Medicine.
Their approach revealed 87 metabolites, or small molecules in the blood, that were significantly different in subjects with AMD and in those without.
Furthermore, the team noted varying characteristics between the blood profiles in each stage of disease. This information has the potential to help diagnose the disease earlier, and ultimately may lead to more treatment options, as well as to personalized treatment for earlier stages of the disease.
Of the 87 molecules identified through metabolomics in the study to be associated with AMD, most belonged to the lipid pathway. In fact, six of the seven most significant metabolites identified were lipids.
Previous research has suggested that lipids may be involved in the development of AMD, although the exact role of lipids in the disease process remains unclear.
The results from this study support this suggestion and indicate that metabolomics profiling may provide novel insights into the relationship between lipids and AMD.
“We believe this work will help launch the era of personalized medicine in treatment of AMD,” said co-senior author and retina specialist Deeba Husain, HMS associate professor of ophthalmology and co-director of the AMD Center of Excellence at Mass. Eye and Ear.
“Our work gives us a novel biomarker for early diagnosis, and it gives us clues to differentiate the progressors from non-progressors. This research also gives us insight into the important role of lipids in AMD, which will provide novel targets for treatment in the early stage of disease, thus preserving vision in AMD,” Husain said.
This research study was supported by the Miller Retina Research Fund, the Champalimaud Vision Award, Research to Prevent Blindness and the Portuguese Foundation for Science and Technology/Harvard Medical School-Portugal Program.