Validation of Retinal Abeta as a Potential Biomarker of Alzheimer's Disease

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PROJECT SUMMARY This application addresses the overarching challenge of detection of the early onset of β-amyloid plaques (Abeta) in Alzheimer's disease (AD). It does so by proposing a novel approach to image retinal Abeta by using signals emitted by curcumin fluorescence (FL). AD is the most common cause of dementia among elderly people. Its pathology is characterized by the presence of extracellular deposits of misfolded and aggregated Abeta peptides, which subsequently spread from the hippocampus to the cerebral cortex causing neuronal death and ultimately loss of memory, logic and the ability to speak. At present, no disease-modifying therapy is effective against AD nor it is possible to diagnose the early onset and/or the progress of the disease. Recent findings indicate that elevated levels of Abeta proteins are associated with dysfunctional neuronal networks both in the brain and eyes. Because AD undergoes a protracted asymptomatic stage before it reaches the advanced stage, a window of opportunity exists for early intervention, and successful detection of the early onset of the disease via routine screening will improve therapeutic outcomes and save lives. In that regard, early detection of Abeta in the eyes at ophthalmology centers, widely available in every health community settings seems ideal in terms of practicality, feasibility, safety and cost. Recently, our group demonstrated a novel approach for delivery of curcumin in vivo via inhalation of the curcumin aerosol. Further, in collaboration with Professor Joanne Matsubara, we recently demonstrated that inhaling curcumin aerosol resulted in significant accumulation of the compound in the retina. Further, we also demonstrated that curcumin binds to Abeta in retinal sublayers. Building on that foundation, we hypothesize that curcumin FL in the eyes can be used as a surrogate biomarker for assessing Abeta levels in the brain. Our long-term objective is to (i) demonstrate the newly synthesized curcumin analogs can be distributed and bind effectively to retinal Abeta; (ii) demonstrate retinal Abeta as a early biomarker of AD. A less well developed, but potentially powerful approach, marrying medicinal chemistry with drug delivery, and targeted molecular imaging, for high sensitivity molecular “fingerprinting” of AD in vivo, is the subject of this high risk-high reward proposal.