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BackgroundEpilepsy is one of the most prevalent neurological diseases, a third of patients remain drug-resistant. The exact etiology of drug-resistant epilepsy (DRE) is still unknown. Neural tetraploidy has been associated with neuropathology. The aim of this study was to assess the presence of tetraploid neurons and astrocytes in DRE.Materials & methodsCortex, hippocampus and amygdala samples were obtained from patients subjected to surgical resection of the epileptogenic zone. Postmortem brain tissue of subjects without previous records of neurological, neurodegenerative or psychiatric diseases were used as controls. The percentage of tetraploid cells was measured by immunostaining of neurons (NeuN) or astrocytes (S100β) followed by flow cytometry analysis. Results were confirmed by image cytometry (ImageStream X Amnis System Cytometer) and with an alternative astrocyte biomarker (NDRG2). Statistical comparison was performed using univariate tests.ResultsA total of 22 patients and 10 controls were included. Tetraploid neurons and astrocytes were found both in healthy individuals and DRE patients in the three brain areas analyzed: cortex, hippocampus and amygdala. DRE patients presented a higher number of tetraploid neurons (p=0.020) and astrocytes (p=0.002) in the hippocampus compared to controls. These results were validated by image cytometry.ConclusionWe demonstrated the presence of both tetraploid neurons and astrocytes in healthy subjects and increased levels of both cell types in DRE patients. This is the first time that tetraploid astrocytes are described in healthy subjects. Furthermore, these results provide new insights into epilepsy, opening new avenues for future treatment.

Epigenetic changes such as DNA methylation were observed in drug-resistant temporal lobe epilepsy (DR-TLE), a disease that affects 25-30% of epilepsy patients. The main objective is to simultaneously describe DNA methylation patterns associated with DR-TLE in hippocampus, amygdala, surrounding cortex to the epileptogenic zone (SCEZ), and peripheral blood. An Illumina Infinium MethylationEPIC BeadChip array was performed in 19 DR-TLE patients and 10 postmortem non-epileptic controls. Overall, 32, 59, and 3210 differentially methylated probes (DMPs) were associated with DR-TLE in the hippocampus, amygdala, and SCEZ, respectively. These DMP-affected genes were involved in neurotrophic and calcium signaling in the hippocampus and voltage-gated channels in SCEZ, among others. One of the hippocampus DMPs (cg26834418 (CHORDC1)) showed a strong blood-brain correlation with BECon and IMAGE-CpG, suggesting that it could be a potential surrogate peripheral biomarker of DR-TLE. Moreover, in three of the top SCEZ's DMPs (SHANK3, SBF1, and MCF2L), methylation status was verified with methylation-specific qPCR. The differentially methylated CpGs were classified in DMRs: 2 in the hippocampus, 12 in the amygdala, and 531 in the SCEZ. We identified genes that had not been associated to DR-TLE so far such as TBX5, EXOC7, and WRHN. The area with more DMPs associated with DR-TLE was the SCEZ, some of them related to voltage-gated channels. The DMPs found in the amygdala were involved in inflammatory processes. We also found a potential surrogate peripheral biomarker of DR-TLE. Thus, these results provide new insights into epigenetic modifications involved in DR-TLE.

Epilepsy is a disabling neurological disease that affects 2% of the population. Drug-resistant epilepsy (DRE) affects 25-30% of epilepsy patients. Understanding its underlying mechanisms is key to adequately manage this condition. To analyze the main epigenetic marks of DRE an epigenome-wide association study was carried out including samples from different regions of DRE patients’ brain and peripheral blood. An Illumina Infinium MethylationEPIC BeadChip array including cortex, hippocampus, amygdala, and peripheral blood from DRE subjected to neurosurgical resection of the epileptogenic zone was used. Overall, 32, 59, 3210, and 6 differentially methylated probes (DMPs) associated with DRE were found in the hippocampus, amygdala, cortex, and peripheral blood, respectively. These DMPs harbored 19, 28, 1574, and 7 genes, respectively, which play different roles in processes such as neurotrophic or calcium signaling. Three of the top DMPs observed in cortex were validated with methylation specific qPCR. Moreover, 163 DMPs associated with neurosurgery response at 6 months were found in the hippocampus. Genes located on these DMPs were involved in diverse processes such as synaptic signaling and central nervous system development. Besides 3 DMPs in blood samples were associated with response to neurosurgery at 12 months. In conclusion, the present study reports genome-wide DNA methylation changes across different regions of the DRE brain. These changes could be useful for further studies to disentangle the bases of DRE to search for therapeutic alternatives for this disease. Furthermore, they could also help identify patients likely to respond to neurosurgery.

[Introduction] Epigenetic factors play an important role in psoriasis onset and development. Biological drugs are used to treat moderate-to-severe psoriasis patients resistant to conventional systemic drugs. Although they are safe and effective, some patients do not respond to them. Therefore, it is necessary to find biomarkers that could predict response to these therapies., [Objective] To find epigenetic biomarkers that could predict response to biological drugs (ustekinumab, secukinumab, adalimumab, ixekizumab)., [Materials and methods] Peripheral blood mononuclear cells (PBMCs) were isolated from 39 psoriasis patients treated with biological therapies before and after drug administration and from 42 healthy subjects. Afterwards, histones were extracted from PBMCs. Four histone modifications (H3 and H4 acetylation, H3K4 and H3K27 methylation) were determined by ELISA. Data were analysed by IBM-SPSS v.23., [Results and conclusions] Psoriasis patients presented reduced levels of acetylated H3 and H4 and increased levels of methylated H3K4 compared to controls. Nonsignificant changes were observed after treatment administration in any of the histone modifications analysed. Nevertheless, significant changes in methylated H3K27 were found between responders and non-responders to biological drugs at 3 months. As 28% of these patients also presented psoriatic arthritis (PsA), the former analysis was repeated in the subsets of patients with or without PsA. In patients without PsA, significant changes in methylated H3K4 were found between responders and nonresponders to biological drugs at 3 and 6 months. Although further studies should confirm these results, these findings suggest that H3K27 and H3K4 methylation may contribute to patients’ response to biological drugs in psoriasis., This study was supported by Instituto de Salud Carlos III PI 13/01598, PI 14/01751, PI 17/01972, Fundación Teófilo Hernando, the Ministry of Science and Innovation and the European Regional Development’s funds (FEDER)