Exosomal microRNA signatures in multiple sclerosis reflect disease status

Abstract

Multiple Sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS). There is currently no single definitive test for MS. Circulating exosomes represent promising candidate biomarkers for a host of human diseases. Exosomes contain RNA, DNA, and proteins, can cross the blood-brain barrier, and are secreted from almost all cell types including cells of the CNS. We hypothesized that serum exosomal miRNAs could present a useful blood-based assay for MS disease detection and monitoring. Exosome-associated microRNAs in serum samples from MS patients (n = 25) and matched healthy controls (n = 11) were profiled using small RNA next generation sequencing. We identified differentially expressed exosomal miRNAs in both relapsing-remitting MS (RRMS) (miR-15b-5p, miR-451a, miR-30b-5p, miR-342-3p) and progressive MS patient sera (miR-127-3p, miR-370-3p, miR-409-3p, miR-432-5p) in relation to controls. Critically, we identified a group of nine miRNAs (miR-15b-5p, miR-23a-3p, miR-223-3p, miR-374a-5p, miR-30b-5p, miR-433-3p, miR-485-3p, miR-342-3p, miR-432-5p) that distinguished relapsing-remitting from progressive disease. Eight out of nine miRNAs were validated in an independent group (n = 11) of progressive MS cases. This is the first demonstration that microRNAs associated with circulating exosomes are informative biomarkers not only for the diagnosis of MS, but in predicting disease subtype with a high degree of accuracy.

Exosomes in Inflammation and Inflammatory Disease

“…Ebrahimkhani et al. conducted a profiling of serum‐derived exosomes from MS patients versus healthy controls and identified panels of miRNAs that could not only be used for the diagnosis of MS, but also to differentiate between relapsing–remitting and progressive subtypes of the disease …”

Deep sequencing of circulating exosomal microRNA allows non-invasive glioblastoma diagnosis

“…Exosomes were isolated from serum as previously described [8] . Briefly, serum (1 mL from each subject) was treated with RNase A (37 °C for 10 min; 100 ng/ml; Qiagen, Australia) before exosome purification by size exclusion chromatography (qEV iZONE Science).…”

“…Ten fractions (500 µL) were eluted in PBS, as per manufacturer's instructions. Fractions 8, 9, and 10 were previously shown to contain purified exosome populations [8] and were collected and stored at −80 °C. Captured exosomes were characterized in accordance with the criteria outlined by the International Society for Extracellular Vesicles (ISEV) [9] .…”

“…1c-2) where certain miRNAs show specific nuclear enrichment [16] . Prior to RNA extraction, serums were treated with RNaseA to remove circulating RNAs that may confound measurements of exosomal RNAs [8] . RNA extracted from each sample yielded profiles typical for exosomes, showing an absence of ribosomal RNA and enrichment of small (<200 nt) RNA species (Fig.…”

“…However, to date no comprehensive analysis of the entire miRNA repertoire of serum exosomes in glioma patients has been performed. Here, we have used unbiased next generation sequencing and an integrative bioinformatics pipeline [8] to assay the complete repertoire of exosomal-associated miRNAs in the serum of patients with glioblastoma, lower grade gliomas, and healthy controls. We describe a novel miRNA signature within serum exosomes that is highly predictive of pre-operative GBM diagnosis.…”