Retinal TDP43 pathology in Alzheimer’s disease, Parkinson’s disease and frontotemporal dementia

Abstract

AbstractBackgroundAs an extension of the brain, the retina displays similarities with the brain in terms of anatomy and functionality. The accessibility of the retina provides a ‘window’ to the brain and a great potential for noninvasive imaging of neurodegenerative changes in patients. TAR DNA binding protein 43 (TDP‐43) is one of the main pathological hallmarks found in frontotemporal lobar degeneration (FTLD). Previously, we identified phosphorylated TDP‐43 (pTDP‐43) aggregation in the retina of FTLD cases with underlying TDP43 (FTLD‐TDP) pathology, including donors with C9orf72 and progranulin (GRN) mutations. The aim of this study is to assess the presence of pTDP‐43 in the retina across various neurodegenerative diseases and controls. This will provide insight in whether the presence of TDP43 pathology in the retina is exclusive for cases with FTLD‐TDP and potentially serve as an in‐vivo biomarker.MethodPost‐mortem eyes were collected by the Netherlands Brain Bank from donors with Alzheimer’s disease (AD), Parkinson’s disease (PD), frontotemporal dementia (FTD) and controls (N = 80). Nasal superior‐temporal quadrants were cut in sections of 10 µm. Immunohistochemical stainings were performed for phosphorylated TDP‐43 (pTDP‐43).ResultFTLD‐TDP cases showed pTDP‐43 immunopositive inclusions in the plexiform layers. Additionally, some AD cases showed sparse pTDP‐43 positive inclusions. Data of the other pathological groups will be available within a couple of months.ConclusionpTDP‐43 is abundantly present in the retina of FTLD‐TDP patients, while only sporadically seen in AD patients. With the advances in ocular imaging techniques, these findings provide a patient friendly retinal biomarker to diagnose FTLD‐TDP. This would be the first FTD specific biomarker, since no other pathology specific biomarkers for the various underlying pathological changes that are known to cause FTD (e.g. tau, FUS, etc), are currently available.