Abstracts

Rationale: Standard clinical practice for diagnosing recurrent seizures or epilepsy relies primarily on clinical history, EEG or neuroimaging information, but is often inadequate. Peripheral blood biomarkers may offer an accurate, economic, and rapid diagnostic solution to enhance epilepsy diagnosis and management. In this pilot study, we investigated whether plasma microRNAs (miRNA) or inflammatory cytokines could serve as potential peripheral biomarkers by profiling expression differences between patients with cryptogenic focal epilepsy, healthy controls, and a neurological control population with chronic migraine. Methods: Adult subjects with cryptogenic, focal epilepsy without other significant medical history were recruited from the Neurology Clinic at Duke University Hospital. Whole blood stabilized in RNA paxgene tubes and EDTA blood samples for DNA and plasma were collected. Demographic and clinical data including last seizures, imaging, EEG, and medications were also collected. For the neurological control group, similar samples and data were collected from subjects with migraines without other significant medical history. Matched healthy control samples were obtained from previously banked samples. MicroRNA sequencing was performed on the NovaSeq platform (Illumina) on plasma samples. Cytokine assays were conducted using a targeted 30-plex MSD platform. Following normalization and batch correction programs, linear and regularized logistic regression models were used to identify differential expression patterns among the focal epilepsy and control groups.  Results: From the analysis of cell free RNA and adjusted for age and sex, we found 34 differentially expressed miRNAs in epilepsy (n=27) versus migraine (n=13) subjects. For the top 10 miRNA candidates, quantitative RT-PCR is being used to confirm the miRNAs dysregulated in epilepsy patients relative to healthy control subjects. We will then determine the utility of individual or combinations of specific miRNA expression patterns that best distinguish between subjects with epilepsy and healthy controls as well as subjects with epilepsy and migraineurs. The inflammatory cytokine changes were minimal. We found only marginal increased expression of IL-7, IL-1a and Eotaxin 3 in epilepsy vs. healthy samples, but a significant increase of IL-7 in migraine samples.  There were no associations with miRNA or cytokine expression and severity characteristics reflected by seizure frequency or duration, and time to last seizure. Conclusions: While larger cohorts are necessary, the findings of this pilot study indicate that dysregulated miRNAs and cytokines may serve as diagnostic biomarkers specific to epilepsy, distinguishing epilepsy from other neurologic conditions. Funding: Pilot Study funds from the Center for Applied Genomics and Personalized Medicine and the Department of Neurology, Duke University Medical Center.Contribution from Ms. Barbara Rosenblatt.