Level Of MiR-142 In Patients With Acute Ischemic Stroke And Role Of MiR-142 In Astrocyte Activation

Objective: Ischemic stroke is a leading cause of morbidity and mortality worldwide,however,lacking clinically-validated treatments and early diagnosis.MicroRNAs(miRNAs),which are endogenous small single-stranded non-coding RNAs and expressed in specific cells,play important roles in the pathological process of ischemic stroke.Astrocyte,the most abundant glial cell in the central nervous system,plays a critical role in the stroke pathological process.Our previous studies found that the expression level of miR-142 significantly decreased in serum of patients with acute ischemic stroke and tMCAO model mice and infarcted tissue of tMCAO model mice.Based on the discoveries above,the study is designed to explore detailed mechanism underlying the role of miR-142 regulating astrocyte activation in the context of stroke,aiming at providing a new insight into the potential diagnosis of ischemic stroke.Methods: Relative serum miR-142 levels between the acute ischemic stroke group and non-stroke group was detected by real-time PCR.ROC carves were generated to discriminate acute ischemic stroke(AIS)patients from non-stroke controls.The correlations between the levels of miR-142 and NIHSS scores,infarct volume and risk factors were examined by Pearson correlation analysis.The effect of tMCAO model and OGD/R on miR-142 expression was evaluated by real-time PCR.The level of miR-142 was detected by fluorescence in situ hybridization in primary mouse astrocytes.The role of miR-142 in astrocytes activation and expression of HMGB1 was validated by lentivirus transfection and western blot assay in vitro.The candidate miR-142 target gene HMGB1 was predicted by TargetScan.The role of HMGB1 in astrocyte activation was illustrated by western blot after lentivirus vector transfection in vitro.Results:1)The level of miR-142 were significantly decreased in the stroke group compared with the control group.2)ROC analyses of miR-142 suggested that miR-142 may be sensitive biomarkers that can identify the AIS patients from non-stroke individuals.3)Significant negative correlation between the serum miR-142 levels and NIHSS scores and infarct volumes.4)The expression level of miR-142 was correlated with stroke risk factors.5)The level of miR-142 in serum and infarcted brain tissue of tMCAO mice and in astrocytes treated with OGD/R was significantly reduced.6)MiR-142 regulated astrocyte activation via downstream target protein HMGB1.Conclusion: In the pathological process of ischemic stroke,the expression of miR-142 is significantly reduced,and miR-142 mediated the expression of its downstream target protein HMGB1,which eventually induced the activation of astrocytes.The expression level of miR-142 was significantly negatively correlated with the degree of brain injury and stroke risk factors,providing a new idea for the accurate and early diagnosis of ischemic stroke.This proof of concept and mechanism study suggested that serum miR-142 was a promising biomarker for diagnosing AIS and evaluating the degree of the damage caused by ischemic injury.