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Expansion of Studies to Develop Tear Biomarkers of Parkinson's Disease

This grant builds upon the research from a prior grant: Identification of Tear Biomarkers for Individuals with Parkinson's Disease

Promising Outcomes of Original Grant:
We previously explored the hypothesis that changes in tear protein content could represent a biomarker -- objective measure -- of Parkinson's disease (PD). Among other changes in the tears of people with PD, we found an increase in oligomeric alpha-synuclein (α-SynOligo) content. Alpha-synuclein is a sticky protein that clumps in the brains of people with Parkinson's; some of it is present in the brain in the form of small clumps called oligomers. The increase in the α-SynOligo content was a highly reliable sign of PD absent in healthy study participants.

Objectives for Supplemental Investigation:
Our initial studies included a small group of individuals with PD. We evaluated tears produced constantly to moisten the eyes (basal) and in response to stimulation (reflex). We also measured levels of six different proteins in tears. In this supplemental study, we will focus only on measurement of α-SynOligo, α-SynTotal (the building block of the oligomeric protein clumps), and on CCL2, another protein of interest that changes in tears during PD. In a larger and more diverse patient cohort, we will collect only reflex tears. Tears will be collected at early, intermediate and late Parkinson's stages to measure tear biomarkers and compare those to tears of healthy people. We will also collect additional information from study participants with PD, which will help us understand other disease features as they relate to production of these proteins in tears.

Importance of This Research for the Development of a New PD Therapy:
Successful completion of this study will support other studies of α-SynOligo and possibly lead to development of other PD biomarkers in tears, confirming their usefulness and also revealing whether these biomarkers can provide information about disease severity. These findings will be critical in advancing the development of tear biomarkers for the use as early diagnostics or even in advancing the development of new therapeutics.


  • Sarah F. Hamm-Alvarez, PhD

    Los Angeles, CA United States

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