Cerebrospinal fluid (CSF) and peripheral blood pleocytosis have been observed after epileptic seizures without any evidence of infections, but no systematic studies on the acute phase reaction in such patients have been performed. We have previously reported increased levels of interleukin-6 (IL-6) in patients with recent tonic--clonic seizures. Because IL-6 is a major inducer of the systemic acute phase reaction, we decided to study various indicators of inflammation in the blood as well as their correlation with plasma and CSF IL-6 levels. CSF and blood samples were studied from 37 patients with previously undiagnosed and untreated tonic-clonic seizures without any clinical evidence of systemic or central nervous system infections as well as from 40 controls. The mean peripheral blood and CSF-leukocyte counts were significantly higher in patients compared with controls ( 7.9 x 10(9)vs. 6.1 x 10(9), P= 0.002 and 1.9 x 10(6)vs. 1.1 x 10(6), P= 0.032, respectively). There was some indication of increased concentration of C-reactive protein (CRP) and no difference in haptoglobin levels. There was a significant correlation between plasma but not CSF IL-6 concentration and those of both B-leukocyte count ( r= 0.051, P= 0.009) and CRP ( r= 0.42, P= 0.009). Epileptic seizures provoke a production of cytokines such as IL-6 that may in turn cause an activation of the acute phase reaction. Thus, CSF pleocytosis and increase in some indicators of inflammation should not automatically be attributed to systemic or CNS infections in patients with acute seizures.

Mitochondria have a complex communication network with the surrounding cell and can alter nuclear DNA methylation (DNAm). Variation in the mitochondrial DNA (mtDNA) has also been linked to differential DNAm. Genome-wide association studies have identified numerous DNAm quantitative trait loci, but these studies have not examined the mitochondrial genome. Herein, we quantified nuclear DNAm from blood and conducted a mitochondrial genome-wide association study of DNAm, with an additional emphasis on sex- and prediabetes-specific heterogeneity. We used the Young Finns Study (n = 926) with sequenced mtDNA genotypes as a discovery sample and sought replication in the Ludwigshafen Risk and Cardiovascular Health study (n = 2317). We identified numerous significant associations in the discovery phase (P < 10−9), but they were not replicated when accounting for multiple testing. In total, 27 associations were nominally replicated with a P < 0.05. The replication analysis presented no evidence of sex- or prediabetes-specific heterogeneity. The 27 associations were included in a joint meta-analysis of the two cohorts, and 19 DNAm sites associated with mtDNA variants, while four other sites showed haplogroup associations. An expression quantitative trait methylation analysis was performed for the identified DNAm sites, pinpointing two statistically significant associations. This study provides evidence of a mitochondrial genetic control of nuclear DNAm with little evidence found for sex- and prediabetes-specific effects. The lack of a comparable mtDNA data set for replication is a limitation in our study and further studies are needed to validate our results.

Background: The effect of mitochondrial DNA variation on peripheral blood transcriptomics in health and disease is not fully known. Sex-specific mitochondrially controlled gene expression patterns have been shown in Drosophila melanogaster but in humans, evidence is lacking. Functional variation in mitochondrial DNA may also have a role in the development of type 2 diabetes and its precursor state, i.e. prediabetes. We examined the associations between mitochondrial SNPs (mtSNPs) and peripheral blood transcriptomics with a focus on sex-and prediabetes-specific effects. Methods: The genome-wide blood cell expression data of 19,637 probes, 199 deep-sequenced mtSNPs, and nine haplogroups of 955 individuals from a population-based Young Finns Study cohort were used. Significant associations were identified with linear regression and analysis of covariance. The effects of sex and prediabetes on the associations between gene expression and mtSNPs were studied using random-effect meta-analysis. Results: Our analysis identified 53 significant expression probe-mtSNP associations after Bonferroni correction, involving 7 genes and 31 mtSNPs. Eight probe-mtSNP signals remained independent after conditional analysis. In addition, five genes showed differential expression between haplogroups. The meta-analysis did not show any significant differences in linear model effect sizes between males and females but identified the association between the OASL gene and mtSNP C16294T to show prediabetes-specific effects. Conclusions: This study pinpoints new independent mtSNPs associated with peripheral blood transcriptomics and replicates six previously reported associations, providing further evidence of the mitochondrial genetic control of blood cell gene expression. In addition, we present evidence that prediabetes might lead to perturbations in mitochondrial control.