Next-generation RNA-Sequencing of serum small extracellular vesicles discovers potential diagnostic biomarkers for dementia with Lewy bodies

Rajkumar, Anto P.; Hye, Abdul; Lange, Johannes; Rashid Manesh, Yazmin; Ballard, Clive; Fladby, Tormod; Aarsland, Dag

Abstract

Objectives: There is an urgent clinical need for identifying blood-based diagnostic biomarkers for Dementia with Lewy Bodies (DLB). Transcriptomic studies have reported unique RNA changes in post-mortem DLB brains. Small extracellular vesicles (SEV) that transport RNA between brain and peripheral circulation enable identifying molecular changes in living human brain. Hence, we aimed to identify differentially expressed RNA in serum SEVs from people with DLB.

Methods: We investigated serum SEV total RNA profiles in people with DLB (n=10) and age and gender matched comparisons (n=10) using next-generation RNA-sequencing. SEVs were separated by ultracentrifugation with density gradient and were characterized by nanoparticle analysis and western blotting. We verified identified differentially expressed genes (DEG) using high-throughput qPCR. Functional implications of identified DEG were evaluated using Ingenuity pathway analyses.

Results: We identified 846 nominally significant DEG including 30 miRNAs in DLB serum SEVs. We identified significant downregulation of pro-inflammatory genes, IL1B, CXCL8 and IKBKB. Previously reported post-mortem DLB brain DEGs were significantly enriched (χ2=4.99; df=1; p=0.03) among the identified DEGs, and the differential expression of 40 post-mortem DLB brain DEGs could be detected in serum SEVs of people living with DLB. Functional pathway and network analyses highlighted the importance of immunosenescence, ubiquitin proteasome system (UPS) dysfunction, DNA repair and RNA post-transcriptional modification deficits in DLB pathology.

Conclusion: Identified DEGs, especially reduced expression levels of inflammation and UPS associated RNA, may aid diagnosing DLB, and their biomarker potential warrants further investigation in larger clinical cohorts. Our findings corroborate the absence of chronic neuroinflammation in DLB.

• Journal Article Type: Article
• Acceptance Date: Oct 22, 2020
• Online Publication Date: Oct 27, 2020
• Publication Date: 2021-06
• Deposit Date: Oct 28, 2020
• Publicly Available Date: Oct 28, 2021
• Journal: American Journal of Geriatric Psychiatry
• Print ISSN: 1064-7481
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 29
• Issue: 6
• Pages: 573-584
• DOI: https://doi.org/10.1016/j.jagp.2020.10.012
• Keywords: Lewy body dementia; Exosomes; High-Throughput RNA sequencing; Quantitative Real-Time Polymerase Chain Reaction; Biomarkers
• Public URL: https://nottingham-repository.worktribe.com/output/4995569
• Publisher URL: https://www.sciencedirect.com/science/article/abs/pii/S1064748120305327