Circulating microRNAs: A Potential Biomarker in TBI and PTSD War Veterans

Traumatic brain injury (TBI) is a debilitating condition caused by one or more concussive insults to the head and is frequently observed in combat Veterans deployed in support of Operation Enduring Freedom (OEF) or Operation Iraqi Freedom (OIF). TBI is associated with impairment of cognitive function and development of post-traumatic stress disorder (PTSD), a psychiatric disorder. Currently, there are no validated biomarkers that can determine the detection of PTSD/TBI in circulation. In this regard, microRNAs (miRNAs) have emerged as specific and sensitive biomarkers in several central nervous system diseases and TBI. The current study evaluated the role of miRNA in circulation TBI and PTSD of OEF and OEF Veterans. While analyzed the expression profile of miRNAs in peripheral blood mononuclear cells (PBMCs) from an OEF/OIF veteran study cohort using a miRNA array and identified several miRNAs in PBMCs of TBI/PTSD compared with control subjects. We confirmed eight selective dysregulated miRNAs by independent quantitative real-time polymerase chain reaction (qRT-PCR) assays. Using bioinformatic tools, we further analyzed target gene function and enrichment analyses using Kyoto Encyclopedia of Genes and Genomes and gene ontology platforms. Based on unsupervised clustering analysis, we validated two miRNAs, miR-142-5p and miR-155-5p with their target genes like BDNF, Nrg1, and NR3C2 by qRT-PCR analyses. Our data suggested a potential link between these two miRNAs and their target genes.