PROJECT SUMMARY Traumatic brain injury (TBI) is the leading cause of acquired disability in children. The evidence available to guide TBI management is disproportionately low relative to its medical and societal burden. Recovery from TBI is determined by the interaction of a multitude of dynamic biological, psychosocial, and therapeutic factors. DNA methylation (DNAm; the methylome) is a major epigenetic regulator of gene expression that responds dynamically to an individual’s internal (e.g., tissue insult) and external (e.g., psychosocial adversity) environment. Initial preclinical and adult clinical studies show differential DNAm both acutely and months after TBI; however, little is known regarding pediatric TBI. Because the methylome is dynamic over time and responsive to both internal and external factors associated with TBI recovery, we hypothesize that the methylome confers risk or protective effects on long-term neurobehavioral recovery through the regulation of genes involved in the brain’s response to TBI. Therefore, interrogation of the methylome could reveal critical information about the biologic complexity underlying recovery, with significant potential for improving future clinical management of pediatric TBI. To further interrogate the methylome as an untapped source of biologic complexity underlying recovery from pediatric TBI, we will generate methylome-wide DNAm data from an ongoing longitudinal study of children aged 3-18 years with complicated mild to severe TBI or orthopedic injury (OI; comparison group). Our two-tiered analytic approach will involve: Tier 1. Comprehensive examination of brain derived-neurotrophic factor (BDNF) DNAm (~55 DNAm sites), grounded in our strong preliminary data; and Tier 2. Unbiased discovery-based analysis of the entire methylome (>935,000 sites), revealing the most significant methylomic signals for future targeted biomarker research. Both Tiers will be examined within each of the following Specific Aims: (1) Determine the association between pediatric TBI and acute DNAm; (2) Identify associations between acute DNAm and long-term neurobehavioral outcomes; (3) Identify associations between acute DNAm and disparities in neurobehavioral outcomes as a function of psychosocial adversity; and (4) Explore associations between longitudinal DNAm and neurobehavioral recovery. Exemplifying rigor and reproducibility, our approach includes analysis of a discovery cohort (235 TBI, 179 OI) followed by replication in an independent cohort (105 TBI, 105 OI). Finally, we will conduct clinical feasibility testing to ensure that only the most rigorous, reproducible, and clinically translatable findings advance for further scientific inquiry. The overall impact of this work will be to advance the field of pediatric TBI towards precision medicine and health equity through an improved understanding of the biologic complexity underlying recovery and its intersection with psychosocial adversity; revealing biologic signatures of risk for poor recovery; and identification of DNAm sites with potential for clinical translation as methylomic biomarkers that could revolutionize TBI management.

PROJECT NARRATIVE The many biological and environmental factors influencing recovery from pediatric traumatic brain injury (TBI) are poorly understood, resulting in inaccurate prediction of outcomes and few effective treatments. This project will investigate DNA methylation/the “methylome”, a major epigenetic regulator of gene expression, as an untapped source of biologic complexity underlying recovery from pediatric TBI. The overall impact of this work will be to improve our understanding of the biologic complexity underlying pediatric TBI recovery, reveal biologic signatures of risk for poor recovery, and identify potential methylomic biomarkers that could revolutionize TBI management.