Time-Dependent Changes in Serum Level of Protein Biomarkers after Focal Traumatic Brain Injury

Artikel i vetenskaplig tidskrift, 2015

Serum biomarkers could indicate the pathological changes during the secondary injury process after traumatic brain injury (TBI). Furthermore, they could reflect specific pathological processes following different types of TBI. Here we analyzed time-dependent changes of select protein biomarkers in serum samples collected from a rodent model of penetrating type of injury (pen-TBI). The model is a controlled penetration of a 2 mm thick needle-shaped object, which is accelerated into the brain tissue with a bullet from an air gun. The results obtained in the current study were compared to previously reported results of levels of serum biomarker following a rotational acceleration injury that mimics mild TBI. A total of 24 animals were used, grouped in normal controls, sham-operated and injured animals. The rats were sacrificed at day 1, day 3 and day 14 post-injury and serum samples were analyzed for Tau, neurofilament heavy chain (NF-H), myelin basic protein (MBP), N-cadherin and S100B. We found that all markers but MBP showing a bi-phasic response to injury. Their serum levels significantly increased at day 1, dropped at 3 and increased again at day 14 post-injury. This was in contrast to rotational TBI model where the peak of biomarkers was found at day 3. Our study suggests that pen-TBI results in both acute axonal and neuronal damages as well as delayed changes likely part of the ongoing secondary injury process. These findings illustrate the dynamics of the injury process in pen-TBI and underline the importance of monitoring changes in serum biomarker levels for more accurate assessment of injury severity and outcome. In addition, comparison to rotational TBI model revealed distinctive temporal pattern of serum biomarker expression dependent on the type of injury.