Abstract: Objective To explore the cellular localization of chemokine (C-X-C motif) ligand 1 (CXCL1) in brain tissue and its expression in brain tissue and blood in patients with severe traumatic brain injury (TBI), as well as its correlation with the injury severity. Methods From September, 2013 to October, 2015, 78 cases of TBI with craniotomy admitted to our hospital were involved as TBI group. A total of 78 peripheral blood samples and 19 brain tissue samples were studied. According to the scores of Glasgow Coma Scale (GCS) at admission, the TBI group was classified as severe TBI group (6~8, n=35) and particularly severe TBI group (3~5, n=43). Ten cases of control brain tissue were taken from patients with cerebral aneurysms or benign tumor and also undergoing craniotomy during the same time. Peripheral blood from ten healthy people were involved as the healthy control group. Immunofluorescent double staining was used to detect the cellular localization of CXCL1 in brain tissues, and ELISA was used to detect the expression of CXCL1 in brain tissue and blood. The relationship between the level of CXCL1 in peripheral blood at different time and the score of Glasgow Outcome Scale (GOS) was analyzed with Spearman correlation analysis. Results In normal brain tissue, CXCL1 mainly localized in astrocytes. For severe TBI, CXCL1 mainly expressed in neurons and astrocytes. The level of CXCL1 was higher in brain tissue in the particularly severe TBI group than in the severe TBI group (t=-12.58, P<0.05). In the severe TBI group, the level of CXCL1 in blood reached a peak before surgery, then gradually decreased, and was still higher than that in the healthy control group 14 days after surgery (P<0.05), however, no significant difference was found 30 days after surgery compared to the healthy control group (P>0.05). In the particularly severe TBI group, the level of CXCL1 in blood reached a peak before and one day after surgery, then gradually decreased, and was still higher than that in the healthy control group 30 days after surgery (P<0.05). The level of CXCL1 in blood was higher in the particularly severe TBI group than in the severe TBI group at all time points (P<0.05), and the level before surgery was negatively correlated with the score of GOS in the particularly severe TBI group (r=-0.351, P<0.05). Conclusion The CXCL1 protein of injury brain tissue was mainly colocalized in neurons and astrocytes in severe TBI patients, and the expression was associated with injury severity and outcome.

Key words: traumatic brain injury, chemokine (C-X-C motif) ligand 1, expression, immunofluorescence staining, correlation analysis