Salivary miRNA Expression in Children With Persistent Post-concussive Symptoms

Abstract

BackgroundUp to one-third of concussed children develop persistent post-concussive symptoms (PPCS). The identification of biomarkers such as salivary miRNAs that detect concussed children at increased risk of PPCS has received growing attention in recent years. However, whether and how salivary miRNA expression levels differ over time between concussed children with and without PPCS is unknown.AimTo identify salivary MicroRNAs (miRNAs) whose expression levels differ over time post-concussion in children with vs. without PPCS.MethodsWe conducted a prospective cohort study with saliva collection at up to three timepoints: (1) within one week of injury; (2) one to two weeks post-injury; and (3) 4-weeks post-injury. Participants were children (ages 11 to 17 years) with a physician-diagnosed concussion from a single hospital center. We collected participants' daily post-concussion symptom ratings throughout their enrollment using the Post-concussion Symptom Scale, and defined PPCS as a total symptom score of ≥ 5 at 28 days post-concussion. We extracted salivary RNA from the saliva samples and measured expression levels of 827 salivary miRNAs. We then compared the longitudinal expression levels of salivary miRNAs in children with vs. without PPCS using linear models with repeated measures.ResultsA total of 135 saliva samples were collected from 60 children. Of the 827 miRNAs analyzed, 91 had expression levels above the calculated background threshold and were included in the differential gene expression analyses. Of these 91 miRNAs, 13 had expression levels that differed significantly across the three timepoints post-concussion between children with and without PPCS (i.e., hsa-miR-95-3p, hsa-miR-301a-5p, hsa-miR-626, hsa-miR-548y, hsa-miR-203a-5p, hsa-miR-548e-5p, hsa-miR-585-3p, hsa-miR-378h, hsa-miR-1323, hsa-miR-183-5p, hsa-miR-200a-3p, hsa-miR-888-5p, hsa-miR-199a-3p+hsa-miR-199b-3p). Among these 13 miRNAs, one (i.e., hsa-miR-203a-5p) was also identified in a prior study, with significantly different expression levels between children with and without PPCS.ConclusionOur results from the longitudinal assessment of miRNAs indicate that the expression levels of 13 salivary miRNAs differ over time post-injury in concussed children with vs. without PPCS. Salivary miRNAs may be a promising biomarker for PPCS in children, although replication studies are needed.

Non-invasive fluid biomarkers in the diagnosis of mild traumatic brain injury (mTBI): a systematic review

“…Only one study assessed multiple biomarkers 10. The most commonly studied biomarker was salivary microRNA which was examined in 11 studies 11–21. Cortisol was assessed in four studies 10 22–24.…”

“…Five studies specifically the paediatric population (≤18 years old) 10 21 25 27 28. However, 82.8% of studies included paediatric subjects.…”

“…Fedorchak et al 13 demonstrated that an algorithm using 16 high performing ncRNAs and patient age was a better predictor of PCS status after 3 weeks post-mTBI (AUC=0.87) than a clinical assessment with balance and cognition testing (AUC=0.73) 13. Miller et al 21 identified 13 miRNAs that significantly changed throughout salivary sampling from acute to chronic time periods. One of these miRNAs was previously reported in Fedorchak et al 13: hsa-miR−203a-5p (table 1).…”

Review on the Role of Salivary Biomarkers in the Diagnosis of Mild Traumatic Brain Injury and Post-Concussion Syndrome

“…A subset of salivary and serum miRNAs predicted the likelihood of a TBI and demonstrated quantitative associations with head impacts and cognitive and balance measures in a group of twenty-four martial arts fighters, and salivary miRNAs demonstrated far more utility [ 59 ]. Miller et al [ 60 ] identified thirteen salivary miRNAs with significantly various levels in children with a history of mild TBI and with or without PPCS.…”

Confounding Factors Impacting microRNA Expression in Human Saliva: Methodological and Biological Considerations

“…Expression studies of miRNAs from human saliva have been increasing over the past decade, across a number of clinical disciplines. Notably, high powered cohort studies identify predictive miRNAs for of autism spectrum disorder [ 4 , 16 , 17 ], traumatic brain injury [ 18 , 19 , 20 , 21 ] endometriosis [ 22 ], and a variety of cancers [ 23 , 24 , 25 ]. Other recent studies include the prediction of alcohol use disorder [ 26 , 27 ], Parkinson’s Disease [ 28 , 29 ], and malignant pleural effusion [ 30 ].…”