Prediction of conversion from mild cognitive impairment to dementia with neuronally derived blood exosome protein profile - PubMed (original) (raw)

Prediction of conversion from mild cognitive impairment to dementia with neuronally derived blood exosome protein profile

Charisse N Winston et al. Alzheimers Dement (Amst). 2016.

Abstract

Introduction: Levels of Alzheimer's disease (AD)-related proteins in plasma neuronal derived exosomes (NDEs) were quantified to identify biomarkers for prediction and staging of mild cognitive impairment (MCI) and AD.

Methods: Plasma exosomes were extracted, precipitated, and enriched for neuronal source by anti-L1CAM antibody absorption. NDEs were characterized by size (Nanosight) and shape (TEM) and extracted NDE protein biomarkers were quantified by ELISAs. Plasma NDE cargo was injected into normal mice, and results were characterized by immunohistochemistry to determine pathogenic potential.

Results: Plasma NDE levels of P-T181-tau, P-S396-tau, and Aβ1-42 were significantly higher, whereas those of neurogranin (NRGN) and the repressor element 1-silencing transcription factor (REST) were significantly lower in AD and MCI converting to AD (ADC) patients compared to cognitively normal controls (CNC) subjects and stable MCI patients. Mice injected with plasma NDEs from ADC patients displayed increased P-tau (PHF-1 antibody)-positive cells in the CA1 region of the hippocampus compared to plasma NDEs from CNC and stable MCI patients.

Conclusions: Abnormal plasma NDE levels of P-tau, Aβ1-42, NRGN, and REST accurately predict conversion of MCI to AD dementia. Plasma NDEs from demented patients seeded tau aggregation and induced AD-like neuropathology in normal mouse CNS.

Keywords: Alzheimer's disease; Beta amyloid; Biomarker; Exosomes; Mild cognitive impairment; Neuron; Phospho-tau.

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Figures

Fig. 1

Fig. 1

Plasma NDEs derived from stable MCI and ADC patients are similar in size and shape to previously reported exosome preparations. (A) Representative TEM image of plasma NDEs derived from a stable MCI patient (scale bars 350 nm; 100 nm). NTA detects high concentrations of plasma NDEs (B) with similar size distributions (C) that are not significantly different between the two patient populations. (C) Representative NTA plot of averaged size/concentration for plasma NDEs derived from a MCI and ADC patient (n = 4/group). Abbreviations: NDE, neuronal derived exosome; MCI, mild cognitive impairment; ADC, MCI converting to AD; TEM, transmission electron microscopy; NTA, nanoparticle tracking analysis.

Fig. 2

Fig. 2

Human plasma NDE levels of P-T181-tau, P-S396-tau, Aβ1–42, NRGN, and REST delineate stages of AD. (A) Plasma NDE levels of CD81 were not statistically different among the four clinical cohorts as measured by ELISA. Significantly different levels of (B) Aβ1–42, (C) P-T181-tau, (D) P-S396-tau, (E) NRGN, and (F) REST were detected by ELISAs in the plasmas of CNC (n = 10), stable MCI (n = 20), ADC (n = 20), and AD (n = 10) patients. Plasma NDE levels of P-T181-tau, P-S396-tau, and Aβ1–42 were significantly higher, whereas those of NRGN and REST were significantly lower for ADC and AD patients than CNC subjects and stable MCI patients. The horizontal line in each cluster depicts the mean for that set. * = P < .05, ** = P < .01, *** = P < .0001 versus CNC; ## = P < .01, ### = P < .0001 versus MCI. Abbreviations: NDE, neuronal derived exosome; CNC, cognitively normal controls; MCI, mild cognitive impairment; ADC, MCI converting to AD.

Fig. 3

Fig. 3

ROC curve analyses assess diagnostic accuracy for plasma NDEs levels of P-T181-tau, P-S396-tau, Aβ1–42, NRGN, and REST. ROC curves based on the plasma NDE levels of P-T181-tau, P-S396-tau, Aβ1–42, NRGN, and REST for (A) CNC subjects versus AD patients, (B) CNC subjects versus stable MCI patients, (C) stable MCI versus ADC patients, and (D) stable MCI versus AD patients. Abbreviations: ROC, receiver operating curve; NDE, neuronal derived exosome; CNC, cognitively normal control; MCI, mild cognitive impairment; ADC, MCI converting to AD.

Fig. 4

Fig. 4

Plasma NDEs from stable MCI and AD patients seed tau aggregation in the brains of normal mice. Representative photomicrographs of hippocampal sections obtained from wild-type, C57/Bl6 mice that were injected with plasma NDEs from control, stable MCI, and ADC patients. At 1-month post-injection, mice injected with plasma NDEs from stable MCI patients display modest enhancement of PHF-1 immunoreactivity in the CA1 region of the hippocampus, whereas mice injected with plasma NDEs from ADC patients display a significant increase in PHF-1 immunoreactivity in the CA1. Extensive cellular staining as well as staining within the dendritic processes can be observed in these mice. Mice-injected NDEs from control plasma displayed no PHF-1 immunoreactivity (n = 6/group; scale bars 250 μm; 25 μm). Abbreviations: NDE, neuronal derived exosome; MCI, mild cognitive impairment; ADC, MCI converting to AD.

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