miRNAs as biomarkers and modulators in asymptomatic carotid stenosis: diagnosis, prognosis, and plaque vulnerability

ENG-This thesis investigates microRNAs (miRNAs), small RNA molecules involved in gene regulation, as potential non-invasive biomarkers to improve the diagnosis and prognosis of ACAS. Because miRNAs are stable and detectable in blood, they hold promise both for early detection and for better understanding the biological mechanisms that make some plaques more likely to rupture and cause a stroke, what is known as a vulnerable plaque. A key first step in the study was to identify specific combinations of reliable endogenous controls for accurately measuring miRNA levels in plasma and plaque samples. This step is key to obtaining consistent and comparable results, as these controls are used to normalise the results. The study then identified several miRNAs in blood as promising diagnostic markers for severe ACAS. Among them, miR-X32 and miR-X29 showed a strong association with ACAS and, when combined with clinical data, achieved excellent diagnostic performance (AUC = 0.988), improving on standard methods. This suggests that, in the future, blood tests based on miRNAs could be used to identify individuals with ACAS more accurately. For prognosis, the study compared miRNA expression in patients with stable versus progressive ACAS. While no circulating miRNAs were confirmed as prognostic biomarkers, one tissue miRNA, miR-X34, was significantly overexpressed in plaques from patients with progressive disease. Further analysis revealed its potential role in regulating proteins linked to plaque instability, offering insights into atherosclerosis mechanisms and pointing to miR-X34 as a possible therapeutic target. In summary, this thesis advances our understanding of the molecular landscape of ACAS and highlights the potential of miRNAs to improve risk assessment and treatment strategies. While more research is needed to validate these findings in larger populations, they represent a step forward in the development of personalised and non-invasive tools for stroke prevention