Abstracts

Rationale: There are no blood-based molecular biomarkers of temporal lobeepilepsy (TLE) to support clinical diagnosis. MicroRNAs are shortnoncoding RNAs with strong biomarker potential due to their cell-specificexpression, mechanistic links to brain excitability, and stable andreliable detection in biofluids. Altered expression of circulatingmicroRNAs has been reported in human epilepsy, but most studies collectedsamples from one clinical site, relied on a single platform for profilingor conducted minimal validation. Methods: Using a case-control design, wecollected plasma samples from video-electroencephalogram-monitored adultTLE patients at epilepsy specialist centers in two different countries,performed genome-wide PCR-based and RNA sequencing during the discoveryphase and validated signatures in a large cohort of samples (>300samples) that included patients with psychogenic non-epileptic seizures. Results: After profiling, validation of the discovery cohort and validation in thelarger patient groups we identified miR-27a-3p, miR-328-3p and miR-654-3pwith biomarker potential. Plasma levels of these microRNAs were similarlychanged in a mouse model of TLE, and furthermore were not different tohealthy controls in patients with psychogenic non-epileptic seizures. Wereport copy number of the three microRNAs in plasma and demonstrate rapiddetection of all three microRNAs using an electrochemical RNAmicrofluidic disk as a prototype point-of-care device. Investigation ofthe molecular transport mechanism in plasma determined that analysis ofall three microRNAs within the exosome-enriched fraction provided highdiagnostic accuracy while levels of Argonaute-bound miR-328-3pselectively increased in patient samples collected after seizures. Insitu hybridization revealed the presence of miR-27a-3p and miR-328-3pwithin neurons in human brain and bioinformatics analysis predictedtargets linked to growth factor signaling and apoptosis. Conclusions: Taken together,this study demonstrates the biomarker potential of circulating microRNAsfor epilepsy diagnosis and mechanistic links to underlyingpathomechanisms. Funding: None