Extracellular Vesicles in Serum and Central Nervous System Tissues Contain microRNA Signatures in Sporadic Amyotrophic Lateral Sclerosis

Abstract

Amyotrophic lateral sclerosis (ALS) is a terminalneurodegenerative disease. Clinical and molecular observations suggest that ALS pathology originates at a single site and spreads in an organized and prion-like manner, possibly driven by extracellular vesicles. Extracellular vesicles (EVs) transfer cargo molecules associated with ALS pathogenesis, such as misfolded and aggregated proteins and dysregulated microRNAs (miRNAs). However, it is poorly understood whether altered levels of circulating extracellular vesicles or their cargo components reflect pathological signatures of the disease. In this study, we used immuno-affinity-based microfluidic technology, electron microscopy, and NanoString miRNA profiling to isolate and characterize extracellular vesicles and their miRNA cargo from frontal cortex, spinal cord, and serum of sporadic ALS (n = 15) and healthy control (n = 16) participants. We found larger extracellular vesicles in ALS spinal cord versus controls and smaller sized vesicles in ALS serum. However, there were no changes in the number of extracellular vesicles between cases and controls across any tissues. Characterization of extracellular vesicle-derived miRNA cargo in ALS compared to controls identified significantly altered miRNA levels in all tissues; miRNAs were reduced in ALS frontal cortex and spinal cord and increased in serum. Two miRNAs were dysregulated in all three tissues: miR-342-3p was increased in ALS, and miR-1254 was reduced in ALS. Additional miRNAs overlapping across two tissues included miR-587, miR-298, miR-4443, and miR-450a-2-3p. Predicted targets and pathways associated with the dysregulated miRNAs across the ALS tissues were associated with common biological pathways altered in neurodegeneration, including axon guidance and long-term potentiation. A predicted target of one identified miRNA (N-deacetylase and N-sulfotransferase 4; NDST4) was likewise dysregulated in an in vitro model of ALS, verifying potential biological relevance. Together, these findings demonstrate that circulating extracellular vesicle miRNA cargo mirror those of the central nervous system disease state in ALS, and thereby offer insight into possible pathogenic factors and diagnostic opportunities.

Small RNA sequencing of circulating small extracellular vesicles microRNAs in patients with amyotrophic lateral sclerosis

“…Although there are many biomarker studies on circulating miRNAs in ALS patients, exosomal miRNAs have been investigated in only a few studies with no overlapped results across studies. Likewise, the two validated miRNAs in present study, miR-192-5p and miR-23c, have not been identified in previous studies 17 – 22 . The inconsistency might be due to a combination of technical and biological factors including different methods for blood sample preparation (serum vs. plasma), EV isolation (precipitation, immuno- or peptide affinity, or a combination of both), miRNA profiling (microarray, RNA sequencing, NanoString), bioinformatic analysis, and biological variability along with disease heterogeneity.…”

Transcriptome-based screening in TARDBP/TDP-43 knock-in motor neurons identifies the NEDD8-activating enzyme inhibitor MLN4924

“…In fact, levels of the 14q32encoded miRNA miR-127-3p were altered in cells of this study as well as in the serum of sporadic and familial ALS patients in two previous studies. 98,99 In addition to biomarkers, miRNAs are also increasingly regarded as potential therapeutic targets, given that miRNAs can modulate hundreds of targets simultaneously. 100 In future work, individual miRNA mimics or synthetic miRNA clusters 101 may be employed to modulate levels of dysregulated miRNAs and their targets to assess phenotypic rescue.…”

Attenuation of amyotrophic lateral sclerosis via stem cell and extracellular vesicle therapy: An updated review

“…miRNAs regulate posttranscriptional processing and may play a central role in regulating the spread of ALS pathology 57 . EVs are an optimal way to quantify miRNAs, as they reflect the state of the source cell from which the EV was derived, protect miRNAs from degradation via their phospholipid bilayer, and can pass through blood–CNS barriers due to their lipophilic nature 53,57,58 . While more research is needed to determine the exact miRNAs altered in ALS, multiple studies have demonstrated upregulated miR‐146a, miR‐151a, and miR‐3919‐3p and downregulated miR‐4454 and miR‐4286 56,57,59,60 .…”