Cerebrospinal Fluid and Plasma Small Extracellular Vesicles and miRNAs as Biomarkers for Prion Diseases.

Óscar López-Pérez,Adelaida Hernaiz,David Sanz-Rubio,Joaquín Castilla,Pilar Zaragoza,Inmaculada Martín-Burriel,Marina Betancor,Olivier Andréoletti,Juan José Badiola,Alicia Otero,Janne M Toivonen,Rosa Bolea

doi:10.3390/ijms22136822

Abstract

Diagnosis of transmissible spongiform encephalopathies (TSEs), or prion diseases, is based on the detection of proteinase K (PK)-resistant PrPSc in post-mortem tissues as indication of infection and disease. Since PrPSc detection is not considered a reliable method for in vivo diagnosis in most TSEs, it is of crucial importance to identify an alternative source of biomarkers to provide useful alternatives for current diagnostic methodology. Ovine scrapie is the prototype of TSEs and has been known for a long time. Using this natural model of TSE, we investigated the presence of PrPSc in exosomes derived from plasma and cerebrospinal fluid (CSF) by protein misfolding cyclic amplification (PMCA) and the levels of candidate microRNAs (miRNAs) by quantitative PCR (qPCR). Significant scrapie-associated increase was found for miR-21-5p in plasma-derived but not in CSF-derived exosomes. However, miR-342-3p, miR-146a-5p, miR-128-3p and miR-21-5p displayed higher levels in total CSF from scrapie-infected sheep. The analysis of overexpressed miRNAs in this biofluid, together with plasma exosomal miR-21-5p, could help in scrapie diagnosis once the presence of the disease is suspected. In addition, we found the presence of PrPSc in most CSF-derived exosomes from clinically affected sheep, which may facilitate in vivo diagnosis of prion diseases, at least during the clinical stage.

Highlights

Transmissible spongiform encephalopathies (TSEs) are fatal neurodegenerative diseases that affect humans and animals [1]
Using this natural model of transmissible spongiform encephalopathies (TSEs), we investigated the presence of PrPSc in exosomes derived from plasma and cerebrospinal fluid (CSF) by protein misfolding cyclic amplification (PMCA) and the levels of candidate microRNAs by quantitative PCR
As in other TSEs, like bovine spongiform encephalopathy in cattle or variant Creutzfeldt-Jakob disease and Kuru in humans, in natural scrapie, prions enter the body through infection of the gastrointestinal tract, accumulate in the lymphoreticular system and access the enteric nervous system (ENS) that seems to be the entry to neural tissues [4]

Summary

Introduction

Transmissible spongiform encephalopathies (TSEs) are fatal neurodegenerative diseases that affect humans and animals [1]. As in other TSEs, like bovine spongiform encephalopathy in cattle or variant Creutzfeldt-Jakob disease (vCJD) and Kuru in humans, in natural scrapie, prions enter the body through infection of the gastrointestinal tract, accumulate in the lymphoreticular system and access the enteric nervous system (ENS) that seems to be the entry to neural tissues [4]. The use of this protein as an effective diagnostic biomarker is not considered a reliable method for in vivo diagnosis since the presence of PrPSc is minimal in accessible tissues and body fluids such as blood or urine [6]. It is necessary to identify biomarkers other than PrPSc that can be detected from accessible tissues or fluids to provide useful alternatives for current diagnostic methodology

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Results

Conclusion