Cerebral ischemic stroke has a significant mortality rate and persistent impairment. The initial diagnosis of stroke occurs by magnetic resonance imaging and computed tomography. There is a strong need for more accessible, less expensive, and non-invasive methods besides the neuroimaging methods. MicroRNAs (miRNAs) are critical regulators for ischemic stroke as they are involved in stroke pathophysiology. The goal of the current study was to determine whether microRNA-221 (miR-221) could be used as a diagnostic biomarker for patients with ischemic stroke, and whether it can serve as a promising indicator of the disease severity especially if combined with interleukin-6 (IL-6). The study included 90 subjects, 45 cerebral ischemic stroke patients and 45 controls. MiR-221 was evaluated by quantitative real-time polymerase chain reaction (q-PCR) and IL-6 by enzyme-linked immunosorbent assay (ELISA). Our study results revealed that the serum miR-221 level was significantly reduced in cerebral ischemic stroke patients when compared to the control group (p<0.0001). In addition, serum miR-221 showed a significant negative correlation with cerebral stroke severity (p<0.0001), whereas serum IL-6 showed a significant positive correlation with cerebral stroke severity (p < 0.0001). We also analyzed the receiver operator characteristic (ROC) curve and found that area under the ROC curve (AUC) for severity of ischemic stroke by miR-221 was 0.97 (95% confidence intervall0.93-1, p<0.001). Notably, the combination of serum miR-221 with IL-6 for prediction of ischemic stroke severity showed both increased sensitivity/specificity (AUC=0.99, 95% confidence interval 0.96-1, p<0.001) than miR-221 alone. We concluded that miR-221 constituted a non-invasive, sensitive, and specific biomarker that could be used for diagnosis of ischemic stroke and for prediction of its severity.
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