Gene expression changes in lymphocytes and monocytes from patients with traumatic brain injury: A prospective case-control study

Background Traumatic brain injury (TBI) can alter various immune functions, including immunosuppression, and constitutes a risk factor for nosocomial infections and organ dysfunction. Although TBI can induce a decline in immune cell function, the detailed mechanisms remains to be elucidated. This study aimed to characterize the mechanism of immunosuppression caused by TBI using a comprehensive transcriptome analysis of immune cells. Methods Six patients with traumatic brain injury and acute subdural hematoma were admitted to our hospital. We focused on three major subsets of immune cells responsible for the immune response: CD4 + T cells, CD8 + T cells, and monocytes. We evaluated the changes in immune function after injury using comprehensive transcriptome analysis. Blood samples were collected immediately after admission and one week later, and the data were compared with those of healthy volunteers. Results CD4 + and CD8 + T cells decreased over seven days following injury, and a decrease in cell adhesion and endoplasmic reticulum function was observed. The results suggested that the process of protein synthesis from RNA was impaired and that overall cell function was reduced. Monocytes also showed a decrease in endoplasmic reticulum function, but classical and nonclassical monocyte subsets showed an increase in functions related to platelet activation and tissue repair. Conclusions Comprehensive transcriptome analysis confirmed a decrease in endoplasmic reticulum function in CD4 + T cells, CD8 + T cells, and monocytes. This study contributes to the further elucidation of the mechanisms of immunosuppression due to trauma.