Abstract: Objective To investigate the expression and clinical significance of ubiquitin C-terminal hydrolase L1(UCH-L1) and neurofilament light chain polypeptide(NF-L) in serum exosomes of patients with acute moderate and severe traumatic brain injury(TBI).
Methods 94 patients with moderate to severe TBI in our Hospital from January 2017 to August 2020 were selected as the observation group,and 52 healthy people in the same period were selected as the control group.At 2 hours,12 hours,24 hours,48 hours and 72 hours after injury,5 ml of peripheral blood was collected to extract exosomes.The concentrations of UCH-L1 and NF-L in exosomes were detected by enzyme-linked immunosorbent assay(ELISA).
Results The concentration of UCH-L1 protein in the peripheral blood of the observation group reached the peak at 12 hours,and then gradually decreased,but it was significantly higher than the corresponding value of the control group at each time point,and the concentration of NF-L protein gradually increased,with significant difference compared with the control group(P<0.05).The protein concentrations of UCH-L1 and NF-L were not correlated with age,gender and whether brain edema was present.UCH-L1 was not correlated with diffuse axonal lesion or focal axonal lesion,but NF-L could well distinguish diffuse axonal lesion from focal axonal lesion(P<0.05).In the patients who died within one week after admission,the concentration of UCH-L1 protein in exosomes increased continuously,and there was a significant difference compared with the patients who did not die(P<0.05).
Conclusion In the early stage of moderate and severe TBI,the levels of UCH-L1 and NF-L in peripheral blood exosomes were significantly increased;NF-L can distinguish diffuse or focal axonal injury,and UCH-L1 can predict the early mortality.The exosomes UCH-L1 and NF-L may be ideal biomarkers for TBI to predict disease severity and prognosis.

Key words: traumatic brain injury, exosome, ubiquitin C-terminal hydrolase L1, neurofilament light chain polypeptide