Overexpression of inflammatory-related and nitric oxide synthase genes in olfactory bulbs from frontal lobe epilepsy patients.

Neuroinflammation has been shown to constitute a crucial mechanism in the pathophysiology of epileptic brain and several genes of inflammatory mediators have been detected in surgically resected hippocampus tissue but not in non-related seizure brain regions. Interestingly, it has been reported an olfactory dysfunction in frontal lobe epilepsy (FLE). Our aim was to quantify the gene expression of inflammatory-related and nitric oxide synthase genes in olfactory bulbs (OB) tissue from FLE patients. RNA was isolated from OB resection of FLE patients and autopsy subjects without any neurological disease (n = 7, each). After cDNA synthesis, we performed qPCR for interleukin-1ß (IL-1ß), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), nuclear factor κB p65 (RELA), Toll-like receptor 4 (TLR 4), its agonist high mobility group box 1 (HMGB 1) as well nitric oxide synthase isozymes (NOS 1, 2 and 3). We found a significant increase in gene expression of pro-inflammatory cytokines (IL-1ß, IL-6 and TNFα), TLR4 receptor and in its agonist HMGB1 and the downstream transcription factor NFκB p65. Moreover, we observed an increase of both NOS1 and NOS3 and a slightly increase of NOS2; however, it was not significant. Our study describes the overexpression of inflammatory-related genes and NOS isozymes in OB from FLE patients. Even though, the number of patients was limited, our findings could point out that neuroinflammation and nitrosative stress-related genes in the OB could be produced in general manner in all brain regions and thus contribute in part, to the olfactory dysfunction observed in FLE patients.

A transcript coding for a partially duplicated form of α7 nicotinic acetylcholine receptor is absent from the CD4+ T-lymphocytes of patients with autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE).

INTRODUCTION: It has been suggested that the homomer-forming α7 subunit (CHRNA7) of the neuronal nicotinic acetylcholine receptor (nAChR) is involved in the pathogenesis of common idiopathic generalized epilepsies (IGEs), whereas mutations of the gene coding for the α4 nAChR subunit (CHRNA4) are associated with autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE). Several genes encoding nAChR subunits, including a partially duplicated isoform of CHRNA7 (CHRFAM7A), are expressed in peripheral blood lymphocytes (PBLs), and are constituents of peripheral receptors corresponding to nAChRs in the brain. Moreover, a 2-bp deletion polymorphism (c.497-498delTG; rs67158670), resulting in a frame shift and truncation of the protein product of the gene, has been found in the CHRFAM7A gene and is associated with some neurological diseases. AIM OF THE STUDY: CHRFAM7A transcript levels in CD4+ T-lymphocytes were compared between ADNFLE patients harbouring the c.851C>T mutation of the CHRNA4 gene and control healthy individuals in order to determine whether there is any correlation between CHRFAM7A expression in CD4+ T-lymphocytes and the severity of epileptic symptoms. We also tested the hypothesis that the 2-bp deletion polymorphism in the partially duplicated α7 nAChR gene may be related to ADNFLE in these patients. MATERIAL AND METHODS: Peripheral venous blood samples were collected from 3 individuals with ADNFLE and from 10 healthy individuals. From the isolated CD4+ T-lymphocytes, RNA was prepared and the CHRFAM7A transcript level was determined by RT-qPCR. In order to compare the CHRNA7 and CHRFAM7A sequences and genotype the -2bp polymorphism, genomic DNA was prepared from PBLs. RESULTS: It has been demonstrated that CHRFAM7A is expressed in CD4+ T-lymphocytes of healthy individuals, the relative abundance of the transcript being nearly equal (about 100 copies per cell), but it is not expressed in ADNFLE patients. Genotype analysis showed that the -2bp polymorphism was found in all patients as well as in seven healthy individuals. CONCLUSIONS: Our observations confirm the hypothesis that the CHRFAM7A gene is expressed in CD4+ T-lymphocytes of healthy individuals and that this expression is legitimate. The observed lack of CHRFAM7A expression in ADNFLE patients might be an important factor in the pathogenesis of ADNFLE.