Proteomic Profiling of Extracellular Vesicles Separated from Plasma of Former National Football League Players at Risk for Chronic Traumatic Encephalopathy.

Annina M Deleo,David Issadore,Harutsugu Tatebe,Kayo Yukawa-Takamatsu,Robert A Stern,Satoshi Muraoka,Seiko Ikezu,Takahiko Tokuda,Tsuneya Ikezu,Zijian Yang

doi:10.14336/ad.2020.0908

Abstract

Chronic Traumatic Encephalopathy (CTE) is a tauopathy that affects individuals with a history of exposure to repetitive head impacts, including National Football League (NFL) players. Extracellular vesicles (EVs) are known to carry tau in Alzheimer’s disease and other tauopathies. We examined protein profiles of EVs separated from the plasma of former NFL players at risk for CTE. EVs were separated from the plasma from former NFL players and age-matched controls using size-exclusion chromatography. Label-free quantitative proteomic analysis identified 675 proteins in plasma EVs, and 17 proteins were significantly differentially expressed between former NFL players and controls. Total tau (t-tau) and tau phosphorylated at threonie181 (p-tau181) in plasma-derived EVs were measured by ultrasensitive immunoassay. Level of t-tau and p-tau181 in EVs were significantly different, and the area under the receiver operating characteristic curve (AUC) of t-tau and p-tau181 showed 0.736 and 0.715, respectively. Machine learning analysis indicated that a combination of collagen type VI alpha 3 and 1 chain (COL6A3 and COL6A1) and reelin (RELN) can distinguish former NFL players from controls with 85% accuracy (AUC = 0.85). Based on the plasma EV proteomics, these data provide protein profiling of plasma EVs for CTE, and indicate combination of COL6A3, RELN and COL6A1 in plasma EVs may serve as the potential diagnostic biomarkers for CTE.

Highlights

Chronic Traumatic Encephalopathy (CTE) is a neurodegenerative tauopathy that is associated with exposure to repetitive head impacts such as those sustained by contact or collision sport athletes, including boxers and American tackle football, soccer, rugby, and ice hockey players [1]
There was statistical difference in body mass index (BMI) between former national football league (NFL) players and control groups but no outlier was detected for Body Mass Index (BMI) in the two groups as determined by Outlier Identifier with ROUT (Q = 1%) (Prism 8, GraphPad)
Extracellular vesicles (EVs) separated from plasma of former NFL players with symptoms consistent with CTE and same-age asymptomatic controls underwent label-free quantitative proteomic profiling by Nano LC-MS/MS

Summary

Introduction

Chronic Traumatic Encephalopathy (CTE) is a neurodegenerative tauopathy that is associated with exposure to repetitive head impacts such as those sustained by contact or collision sport athletes, including boxers and American tackle football, soccer, rugby, and ice hockey players [1]. A recent study provided preliminary support for the use of the positron emission tomography (PET) p-tau ligand flortaucipir to detect CTE in living former national football league (NFL) players [7]. Extracellular vesicles (EV), including exosomes (50150nm), ectosomes/microvesicles (150-1000nm) and apoptotic bodies (1000-5000nm) are released into the extracellular space by almost all cell types in the central nervous system (CNS), including neurons and glia [1315]. These vesicles are found in saliva, Urine, blood and CSF [16,17,18,19]. We provide the first proteomic profiling of EVs separated from former NFL players’ plasma samples

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Conclusion