The plasma miRNAome in ADNI: Signatures to aid the detection of at-risk individuals

Preclinical Alzheimer's disease shows alterations in circulating neuronal-derived extracellular vesicle microRNAs in a multiethnic cohort

INTRODUCTION

Alzheimer's disease (AD) is the leading cause of dementia, affecting around 50 million individuals worldwide. Brain-derived extracellular vesicles (EVs) can cross the blood-brain barrier carrying neuron-specific molecules, such as microRNAs (miRNAs), which have potential as biomarkers of neurodegeneration.

METHODS

We explored the association between neuronal-derived EV miRNAs from serum and AD clinical status by performing a transcriptome-wide association study involving 46 participants with clinical AD, 14 participants with preclinical AD, and 60 neurologically healthy controls.

RESULTS

We identified 14 miRNAs associated with AD risk, with more pronounced transcriptional alterations in preclinical individuals compared to clinical AD individuals. Functional analysis revealed enrichment of miRNA-target genes in neurodegenerative pathways, highlighting synuclein alpha (SNCA), cytochrome c, somatic (CYCS), and microtubule associated protein tau (MAPT) as key targets.

DISCUSSION

Our results highlight the potential role of neuronal-derived EVs in neurodegeneration and suggest avenues for further research into brain-derived biomarkers.

HIGHLIGHTS

Neuronal-derived extracellular vesicles (NDEVs) carry potential brain biomarkers. We tested the association between NDEV microRNAs (miRNAs) and Alzheimer's disease (AD). Fourteen NDEV miRNAs were associated with AD. Preclinical AD displayed more pronounced transcriptional changes than clinical AD. miRNA-target genes were enriched in pathways associated with neurodegeneration.

Plasma miRNAs across the Alzheimer's disease continuum: Relationship to central biomarkers

INTRODUCTION

MicroRNAs (miRNAs) play important roles in gene expression regulation and Alzheimer's disease (AD) pathogenesis.

METHODS

We investigated the association between baseline plasma miRNAs and central AD biomarkers from the Alzheimer's Disease Neuroimaging Initiative (ADNI; N = 803): amyloid, tau, and neurodegeneration (A/T/N). Differentially expressed miRNAs and their targets were identified, followed by pathway enrichment analysis. Machine learning approaches were applied to investigate the role of miRNAs as blood biomarkers.

RESULTS

We identified nine, two, and eight miRNAs significantly associated with A/T/N positivity, respectively. We identified 271 genes targeted by amyloid-related miRNAs with estrogen signaling receptor-mediated signaling among the enriched pathways. Additionally, 220 genes targeted by neurodegeneration-related miRNAs showed enrichment in pathways including the insulin growth factor 1 pathway. The classification performance of demographic information for A/T/N positivity was increased up to 9% with the inclusion of miRNAs.

DISCUSSION

Plasma miRNAs were associated with central A/T/N biomarkers, highlighting their potential as blood biomarkers.

HIGHLIGHTS

We performed association analysis of microRNAs (miRNAs) with amyloid/tau/neurodegeneration (A/T/N) biomarker positivity. We identified dysregulated miRNAs for A/T/N biomarker positivity. We identified Alzheimer's disease biomarker-specific/common pathways related to miRNAs. miRNAs improved the classification for A/T/N positivity by up to 9%. Our study highlights the potential of miRNAs as blood biomarkers.