Circulating miRNAs Associated With 3-Month Outcome in Patients With Acute Ischemic Stroke.

Background and objectives: Post-ischemic stroke (IS) outcomes vary widely among individuals, independently of clinical factors. This variability could be related to epigenetic mechanisms that regulate biological processes involved in recovery after ischemia. While several microRNAs (miRNAs) and their target genes are implicated in the pathophysiology of IS, their role in functional outcomes remains unclear. Our aim is to identify potential miRNAs associated with the 3-month outcome in patients with IS.

Methods: A discovery study was performed in patients with acute IS assessed at Hospital del Mar of Barcelona from 2009 to 2018. Main inclusion criteria were initial NIH Stroke Scale (NIHSS) score >2, hospital admission within 24 hours of IS onset, and previous functional independence. Poor 3-month outcome was defined as a modified Rankin Scale score >2. We performed miRNA next-generation sequencing on plasma samples obtained within 24 hours and performed a differential expression analysis for 2,083 miRNAs using the DESeq2 package. A replication stage was performed using real time-PCR in another multicenter cohort, with equivalent inclusion criteria and multivariate regression models. We also performed enrichment pathways analyses in both phases.

Results: The discovery cohort included 215 patients with IS (mean age 74.7 ± 10.2 years, 54.9% male). Age, sex, and stroke severity (measured with the 24-hour NIHSS) were associated with the 3-month outcome (p < 0.05). After adjusting for these potential confounders, we found 74 miRNAs significantly associated (Q < 0.05) with the 3-month poor outcome. Pathway analysis revealed significant associations with pathways related to angiogenesis, neuronal morphogenesis, transforming growth factor β (TGF-β), endothelial development, and cognition. The replication included 191 patients (mean age 78.0 ± 6.0 years, 49.7% male). We analyzed 26 miRNAs selected from the discovery stage, and 5 miRNAs replicated their association with poor outcomes (p < 0.05, fold change >1.7): miR-376c-3p, miR-4463, miR-199a-3p, miR-584-5p, and miR-134-5p.

Discussion: We identified 5 miRNAs overexpressed in patients with poor 3-month outcomes after IS, which could be involved in biological processes such as cognition, neuronal morphogenesis, and TGF-β response, suggesting a potential role in brain recovery. These findings were not evaluated in infratentorial and lacunar strokes, which limits generalizability in these particular subtypes. Further investigation is needed to explore potential applicability of these findings.