Researchers in the Retinal Biology Program in Neuroscience of the Wayne State University Department of Neurology have developed a novel biomarker for Parkinson's disease.
Using three dimensional optical-coherence tomography, or OCT, Omar Khan, M.D., professor and chair of Neurology, published "Characterization of Retinal Architecture in Parkinson's Disease" in the May issue of the Journal of the Neurological Sciences.
"Optical coherence tomography provides a unique opportunity to investigate retinal morphology relevant to neuronal function and synaptic transmission," Dr. Khan said. "Advances in intra-retinal segmentation have created opportunities for investigating neurodegenerative disorders, including Parkinson's disease, with the potential to develop biomarkers."
The aggregation of alpha-synuclein, a presynaptic neuronal protein linked genetically and neuropathologically to Parkinson's disease, plays a central role in the etiology of the condition and forms aggregates in Lewy bodies in the brain and retina, Dr. Khan explained. Lewy bodies are abnormal aggregates of protein that develop inside nerve cells in Parkinson's disease and some dementia disorders. Compared to age-matched healthy controls, patients with Parkinson's disease demonstrated thickening of the layer know as outer plexiform layer, a layer of neuronal synapses contained in the retina. Human autopsy studies, as well as tissue mRNA studies, have localized alpha-synuclein in the deeper layers of retina, including the outer plexiform layer.
"This is the first study in Parkinson's disease that shows that enlargement of the outer plexiform layer may represent a potential biomarker of a-synuclein aggregation. This may have significant clinical implications on diagnosing and monitoring disease progression in Parkinson's disease," Dr. Khan said.
Several clinical approaches based on vaccinating against alpha-synuclein aggregation are under way. "Our novel biomarker discovery of alpha-synuclein detection in the retina in Parkinson's disease provides an easy and reliable method to monitor response to alpha-synuclein vaccination therapeutic strategy is Parkinson's disease, Dr. Khan said.
Commenting on the study, Dr. Edwin George, Director of the Movement Disorders Center, Department of Neurology, said,
"Our findings warrant larger prospective studies that include clinical and other investigations of the anterior visual pathway in Parkinson's disease," said Edwin George, M.D., Ph.D., assistant professor of Neurology and director of the department's Movement Disorders Center. "In particular, we are intrigued by the in-vivo detection of alpha-synuclein, which opens the door for this unique biomarker development in Parkinson's disease."
The study exemplifies the translational research conducted by the Retinal Biology Program in Neuroscience in the Department of Neurology. "This was a team effort and several researchers contributed to the success of the study, including collaborators from Duke University and University of Texas Southwestern," Dr. Khan said. "Our Retinal Biology Program, led by research investigator Jessica Chorostecki, the lead author of the study, is now poised to conduct cutting-edge translational research leading to biomarker and therapeutic development using retinal characterization of neurodegenerative diseases."
Dr. Khan, who also is director of the Sastry Foundation Advanced Imaging Laboratory, thanked the Sastry family for its generosity.
"In the two years since the program was established, we have embarked on an ambitious and successful program investigating Parkinson's disease using both brain magnetic resonance imaging and retinal imaging. This has also opened the door to investigate neurodegenerative disorders, including Alzheimer's disease and Huntington's disease," said Navid Seraji-Bozorgzad, M.D., assistant professor of Neurology and associate director of the Sastry Foundation Advanced Imaging Laboratory.