Elizabeth Brindley, Thomas D.M.Hill, David C.Henshall
Microribonucleic acids (miRNAs) are short noncoding ribonucleic acids (RNAs) that have been proposed as potential biomarkers for epilepsy, acute seizures, and status epilepticus. Various properties support their potential in this regard, including relative stability and amenability to rapid quantitation in biofluids. Several miRNAs are enriched in the brain and within specific cell types. Dysregulation of miRNAs has been reported in brain regions damaged by status epilepticus and in resected brain tissue from patients with drug-resistant epilepsy. Silencing miRNAs using antisense-like oligonucleotides termed antagomirs has been reported to suppress evoked and spontaneous seizures in animal models, indicating therapeutic applications. The prospect of miRNAs as mechanistic biomarkers is supported by recent studies showing blood levels of brain-enriched miRNAs increase after status epilepticus in rodents, and clinical studies have identified miRNAs upregulated in human cerebrospinal fluid after status epilepticus. It remains unproven, however, whether there are miRNAs that uniquely identify acute seizures, chronic epilepsy, or the process of epileptogenesis. Finally, efforts have turned to the challenge of proving that some of the circulating miRNAs actually originate from the brain. New models that feature a biochemically-labeled protein involved in miRNA function and restricted to specific brain cell types offer opportunities to resolve this issue. This review summarizes recent progress on miRNAs as diagnostic biomarkers of status epilepticus and considers some of the unanswered questions and future directions.