Microwave and magnetic (M2) proteomics of a mouse model of mild traumatic brain injury

• M2 proteomics is a rapid method to study mild traumatic brain injury.
• M2 proteomics can reveal changes in CNS-specific protein (CSP) expression.
• CSP expression can be related to long-term effects on motor impairment.

Short-term increases in oxidative stress and decreases in motor function, including debilitating effects on balance and motor control, can occur following primary mild traumatic brain injuries (mTBI). However, the long-term effects on motor unit impairment and integrity as well as the molecular mechanisms underlying secondary injuries are poorly understood. We hypothesized that changes in central nervous system-specific protein (CSP) expression might correlate to these long-term effects. To test our hypothesis, we longitudinally assessed a closed-skull mTBI mouse model, vs. sham control, at 1, 7, 30, and 120 days post-injury. Motor impairment was determined by rotarod and grip strength performance measures, while motor unit integrity was determined using electromyography. Relative protein expression was determined by microwave and magnetic (M2) proteomics of ipsilateral brain tissue, as previously described. Isoprostane measurements were performed to confirm a primary oxidative stress response. Decoding the relative expression of 476 ± 56 top-ranked proteins for each specimen revealed statistically significant changes in the expression of two well-known CSPs at 1, 7 and 30 days post-injury: P < 0.001 for myelin basic protein (MBP) and p < 0.05 for myelin associated glycoprotein (MAG). This was confirmed by Western blot. Moreover, MAG, αII-spectrin (SPNA2) and neurofilament light (NEFL) expression at 30 days post-injury were directly related to grip strength (p < 0.05). While higher-powered studies of larger cohorts merit further investigation, this study supports the proof-of-concept that M2 proteomics is a rapid method to quantify putative protein biomarkers and therapeutic targets of mTBI and suggests the feasibility of CSP expression correlations to long-term effects on motor impairment.

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