Impact of Age on Plasma Inflammatory Biomarkers in the 6 Months Following Mild Traumatic Brain Injury.

Abstract

To compare plasma inflammatory biomarker concentrations to 6 months in young and older adults with and without mild traumatic brain injury (TBI). Level 1 trauma center. Younger (21-54 years) and older (55+) adults diagnosed with mild TBI along with age-/sex-matched noninjured controls (n = 313). Prospective cohort study. Multiplex assays were used to quantify concentrations of selected plasma inflammatory markers at day 0, months 1 and 6. Persistent aging-related differences were found between control groups in concentrations of 4 cytokines up to 6 months. At day 0, interleukin-6 (IL-6), IL-8, and fractalkine were higher in the older TBI compared with older control as well as the younger TBI groups, while IL-10 was higher in older TBI compared with controls. At month 1, significantly higher concentrations of IL-8, fractalkine, and tumor necrosis factor-α (TNF-α) were seen. At 6 months postinjury, significantly higher concentrations of IL-6 and IL-8 were seen, while a lower concentration of IL-7 was found in older versus younger TBI groups. The neuroinflammatory signature that accompanies mild TBI in older adults differs from that of younger adults. The differences seen are notable for their roles in neutrophil attraction (IL-8), neuronal-microglial-immune cell interactions (fractalkine), and chronic inflammation (IL-6).