Abstract: Objective To identify the prognostic serum markers of closed craniocerebral injury,and provide a new basis for early prediction of the prognosis of closed craniocerebral injury.Methods Bioinformatics analysis of the Gene Expression Omnibus(GEO) GSE123336 dataset revealed a potentially valuable miRNA-miR-125b-2-3p.To redict possible dysregulation mechanisms,enrichment analysis and miRNA target gene prediction were performed using the mirPATH database.Quantitative reverse transcription polymerase chain reaction(qRT-PCR) was used to detect the expression of miR-125b-2-3p in the serum samples of patients with closed head injury collected in our hospital.Anlysis of expression of miR-125b-2-3p to verify whether the differential expression exist and relationship with Glasgow coma scale(GCS)/Glasgow Outcome Scale(GOS).Results The top3 differential genes in the GEO GSE123336 database were miR-125b-2-3p,miR-10b-5p,and miR-99b-5p.The enrichment analysis of differential miRNAs suggested that miR-125b-2-3p was closely associated with the MAPK pathway and the sphingolipid signaling pathway.The expression of miR-125b-2-3p increased significantly after head injury(23.79±24.96) than before(5.35±6.28)(P<0.05).The expression of miR-125b-2-3p in samples from our hospital increased with the severity of the brain injury(mild head injury 1.02±0.36,moderate injury 2.23±0.53,severe injury 3.33±0.90,extra severe injury 3.74±1.06),P<0.05.The expression of miR-125b-2-3p is negatively correlated with the patient's Glasgow Coma Scale,and significantly positively correlated with the severity of injury.Further analysis indicated that the serum expression of miR-125b-2-3p was negatively correlated with GOS(Glasgow Outcome Scale)(Ⅰ/Ⅱ 4.12±0.74，Ⅲ 3.45±0.51，Ⅳ 2.40±0.66，Ⅴ 1.34±0.71,P<0.05).Conclusions Serum miR-125b-2-3p is a potential prognostic marker of closed head injury.The high expression of serum miR-125b-2-3p indicates a poor prognosis.

Key words: brain injury, miRNA, miR-125b-2-3p, biomarker, prognosis