Salivary MicroRNAs: Diagnostic Markers of Mild Traumatic Brain Injury in Contact-Sport

Abstract

Concussion is difficult to diagnose, particularly when symptoms are atypical or late in presenting. An accurate and timely initial assessment is crucial for clinical management. Cerebral spinal fluid (CSF) and blood markers of traumatic brain injury show promising results but their clinical applicability in concussion has significant limitations. In the study, we explored saliva as a new source of biomarkers of concussion. Saliva samples of concussed players were collected after 48–72 h from concussion and analyzed by high-throughput technologies. A discovery group of 10 concussed rugby professional and semiprofessional athletes and 10 non-concussed matched controls was used for the analysis of 92 inflammatory proteins by the Proseek-Multiplex-Inflammation technology. In addition, saliva samples of 6 concussed and 6 non-concussed athletes were used to screen 800 human microRNAs (miRNAs) by the Nanostring Technology. The results were then validated by RT-qPCR in an enlarged cohort (validation group) comprising 22 concussed athletes. Results showed, no significant variations of the 65 inflammatory proteins detected in saliva between groups but 5 microRNAs, miR-27b-3p (p = 0.016), let-7i-5p (p = 0.001), miR-142-3p (p = 0.008), miR-107 (p = 0.028), miR-135b-5p (p = 0.017) significantly upregulated in concussed athletes. Univariate ROC curve analysis showed that the differentially expressed miRNAs could be considered good classifiers of concussion. Further analyses showed significant correlation between these microRNAs and Reaction Time component of the ImPACT concussion assessment tool. In addition, biocomputation analysis predicted the involvement of these microRNAs in important biological processes that might be related to trauma, such as response to hypoxia, cell death, neurogenesis, axon repair and myelination. Ease of access and non-invasiveness of saliva samples make these biomarkers particularly suitable for concussion assessment.

Plasma Exosome-derived MicroRNAs as Novel Biomarkers of Traumatic Brain Injury in Rats

“…These altered miRNAs might participate in the progression of TBI. Several previous studies have demonstrated the involvement of various spectrums of miRNAs from different sources in the TBI process, including miRNAs from cerebrospinal fluid (CSF) [22], serum [22], brain tissue [23], and saliva [32]. Compared to these samples, CSF or brain tissue is difficult to obtain in an emergency room (ER), and preparation of serum usually takes hours, while plasma can be acquired relatively easily along with blood tests in ER.…”

Saliva microRNA Biomarkers of Cumulative Concussion

“…Epigenetic mechanisms have the ability to alter cellular function in response to an external insult, and have been implicated in the chronic effects of mild traumatic brain injury [ 25 ]. Microribonucleic acids (miRNAs) are small epitranscriptional molecules that are critical to neuronal function [ 26 ], and regulate gene expression in response to traumatic brain injury [ 27 , 28 ]. Neurons have the ability to package miRNAs within protective exosomes as an intracellular signaling mechanism [ 29 ].…”

Uncharacterized RNAs in Plasma of Alzheimer’s Patients Are Associated with Cognitive Impairment and Show a Potential Diagnostic Power

“…However, several reports showed promising results that have not been confirmed in independent studies [ 7 ]. The application of circulating RNA molecules, including non-coding RNAs (ncRNAs), as biomarkers has been widely explored in the last few decades; miRNAs have been suggested as diagnostic biomarkers for several diseases, including neurodegenerative [ 8 , 9 ], neurodevelopmental [ 10 ], traumatic [ 11 ], neoplastic [ 12 , 13 ], and metabolic conditions [ 14 , 15 ]. Indeed, miRNAs have been detected in all analyzed biological fluids [ 16 , 17 , 18 ], making them useful as disease biomarkers measurable in all body districts.…”