Hospital Universitario de Getafe
Neurology

Author Of 1 Presentation

Genetics and Epigenetics Oral Presentation

PS08.05 - Functional changes associated to the Multiple Sclerosis risk polymorphism in the HHEX gene

Speakers
Presentation Number
PS08.05
Presentation Topic
Genetics and Epigenetics
Lecture Time
13:39 - 13:51

Abstract

Background

Genome-wide association studies (GWAS) identified 233 SNPs (Single Nucleotide Polymorphisms) increasing multiple sclerosis (MS) susceptibility, with a main involvement of immune peripheral cells and microglia. One of these variants, rs7923837, described as eQTL in healthy individuals, is located near the HHEX (Hematopoietically Expressed Homeobox) gene, which encodes a key transcription factor in lymphopoiesis and contributes to metabolism-related traits and diseases.

Objectives

We aimed at understanding the impact of rs7923837 polymorphism located in the 3'UTR (Untranslated Region) of the HHEX gene on MS risk

Methods

The study included 154 MS patients and 117 healthy controls. The SNP rs7923837 was genotyped by TaqMan technology. Levels of expression of the HHEX gene were ascertained by real time PCR and normalized to the GUS housekeeping gene. HHEX nuclear translocation was analyzed by confocal microscopy. Extracellular acidification (ECAR) and oxygen consumption rate (OCR) were measured in peripheral blood mononuclear cells (PBMCs) with and without phytohemagglutinin (PHA) stimulation, in a Seahorse XFp Extracellular Flux Analyzer (Agilent). Mitochondrial mass was measured by FACS in PBMCs with mitotracker florescence probe.

Results

Lower levels of expression of the HHEX gene were detected in MS patients compared to controls (p=0.037). As previously described in whole blood of healthy controls, the risk polymorphism acts as eQTL in PBMCs of MS patients. The AA genotype not only showed reduced levels of mRNA expression in MS patients, but also an increased nuclear localization, in contrast to the lower nuclear localization found in controls with this genotype. In addition, PHA stimulation in PBMCs of AA-homozygotes significantly increased mitochondrial mass in controls compared with MS patients (p=0.009). The influence of genotypes in rs7923837 on the values of ECAR and OCR, indicative of glycolysis and oxidative phosphorylation respectively, were analyzed. Significant differences in ECAR were evidenced by comparison of either homozygous genotype between MS patients and controls. In basal conditions, a consistent trend to higher OCR was observed for MS patients compared with healthy controls. After PHA stimulation, AA-homozygous individuals presented increased mitochondrial maximal respiration and spare respiratory capacity, and AA-homozygous patients showed higher no mitochondrial oxygen consumption.

Conclusions

In MS patients, the homozygous AA genotype of rs7923837 in HHEX determines low levels of mRNA expression and increased nuclear location, presumably altering its function as a transcription factor. Moreover, MS patients display higher values than healthy controls in some parameters of mitochondrial respiration. Those differences are increased in minor allele homozygotes for rs7923837, and reflect a differential coupling between minor and major homozygous genotypes in MS patients.

Collapse

Author Of 1 Presentation

Biomarkers and Bioinformatics Poster Presentation

P0109 - microRNA expression and its association with disability and brain atrophy (ID 1255)

Abstract

Background

MicroRNAs (miRNAs) are endogenous, non coding, small RNAs with post-transcriptional regulating functions. They participate in several cellular processes, including inflammation, neurodegeneration and remyelination

Objectives

To correlate serum miRNAs profile expression with disability, cognitive functioning and brain volume in patients with remitting-relapsing multiple sclerosis (RRMS)

Methods

Cross-sectional study in RRMS patients on stable treatment with glatiramer acetate (GA) during at least 6 months.

We selected the 20 best miRNAs candidates for RRMS and cognitive dysfunction through simple topological analysis (Anaxomics ®). MiRNAs profile was determined with LNA-based PCR (Exiqon). Clinical variables were Expanded Disability Status Scale (EDSS), Symbol Digit Modalities Test (SDMT) and brain volume (whole brain volume, grey matter volume, white matter volume, cerebellum volume, basal ganglia volume and T1 lesion load volume) (automatic software NeuroQuant ®). Correlation was analyzed with Spearman correlation coefficient (r) (p<0,05; software: SPSS)

Results

We included 20 patients (13 women), age 38,2 (29,4, 47,8) years, duration of disease: 5,1 (1,5, 8,5) years, and time on GA 2,1 (0,8, 6) years. We found a pathogenic association between miR.146a.5p and has.mir.9.5p with EDSS (r:0,434, p=0,03; r:0,516, p=0,028); miR.146a.5p with SDMT (r:-0,476, p=0,016); has.mir.9.5p with thalamus (r:-0,545, p=0,036), and miR.200c.3p with pallidum and cerebellum (r:-0,675, p=0,002; r:-0,472, p=0,048).

Conclusions

MiRNAs could be useful biomarkers in multiple sclerosis. We would like to highlight the association of proinflammatory has.mir.9.5p with EDSS and thalamus volume. They are needed more studies to confirm this findings.

Collapse