Systematic review and meta-analysis of dysregulated microRNAs derived from liquid biopsies as biomarkers for amyotrophic lateral sclerosis

Abstract

The discovery of disease-specific biomarkers, such as microRNAs (miRNAs), holds the potential to transform the landscape of Amyotrophic Lateral Sclerosis (ALS) by facilitating timely diagnosis, monitoring treatment response, and accelerating drug discovery. Such advancement could ultimately improve the quality of life and survival rates for ALS patients. Despite more than a decade of research, no miRNA biomarker candidate has been translated into clinical practice. We conducted a systematic review and meta-analysis to quantitatively synthesize data from original studies that analyzed miRNA expression from liquid biopsies via PCR and compared them to healthy controls. Our analysis encompasses 807 miRNA observations from 31 studies, stratified according to their source tissue. We identified consistently dysregulated miRNAs in serum (hsa-miR-3665, -4530, -4745-5p, -206); blood (hsa-miR-338-3p, -183-5p); cerebrospinal fluid (hsa-miR-34a-3p); plasma (hsa-miR-206); and neural-enriched extracellular vesicles from plasma (hsa-miR-146a-5p, -151a-5p, -10b-5p, -29b-3p, and -4454). The meta-analyses provided further support for the upregulation of hsa-miR-206, hsa-miR-338-3p, hsa-miR-146a-5p and hsa-miR-151a-5p, and downregulation of hsa-miR-183-5p, hsa-miR-10b-5p, hsa-miR-29b-3p, and hsa-miR-4454 as consistent indicators of ALS across independent studies. Our findings provide valuable insights into the current understanding of miRNAs' dysregulated expression in ALS patients and on the researchers' choices of methodology. This work contributes to the ongoing efforts towards discovering disease-specific biomarkers.

Keywords: ALS; Biomarkers; Dysregulated expression; Liquid biopsies; miRNAs.

Fig. 1

Data workflow and characteristics of ALS patients. (A) Flow diagram following the PRISMA guideline (2020) for the article selection process. The last manual search was conducted on January 30, 2023, which did not yield new records. (B) Summary from Table S1 on the extracted data from the 31 selected articles. Abbreviations: N/I, not informed; ALS-FP, fast-progressing ALS; ALS-SP, slow-progressing ALS; ALSFRS/-R, ALS functional rating scale/-revised; K-ALS, Kii peninsula ALS; EVs, extracellular vesicles; CSF, cerebrospinal fluid; ALS-PDC Kii Med Manual, medical manual for ALS and Parkinsonism-dementia complex of the Kii Peninsula of Japan; ENMG, Electroneuromyography; El-Escorial/-R, -revised.

Fig. 2

Synthesis of screened miRNAs from different tissues. (A) Representation of miRNAs screened in ALS liquid biopsies. (B) Overlap of consistently dysregulated miRNAs, either up- or downregulated, across different tissues. The analysis includes miRNAs with at least two independent datasets. Abbreviations: EVs, extracellular vesicles; CSF, cerebrospinal fluid; NEE, neural-enriched EVs.

Fig. 3

Meta-analysis publication bias and forest plot. (A) The result of p-curve analysis on statistically significant miRNA results reported from all 31 studies, demonstrating low publication bias and high study power. (B) The forest plot of the estimated log₂ fold change for hsa-miR-206 in ALS samples vs healthy control, demonstrating a consistent upregulation despite conservatively high estimates of within-study variance. The last line of the forest plot is our estimated effect size.

Fig. 4

The heatmap illustrates the KEGG pathways associated with the 12 consistently identified miRNAs. The gradient color scheme indicates the strength of association, with closer interactions shown in red (lower p-value).

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