Toll-like receptor-9 in Spanish multiple sclerosis patients: an association with the gender

BACKGROUND AND PURPOSE

Toll-like receptor-9 (TLR9) is a potent inducer of innate immune system triggered by infection with viruses, some of them previously related to multiple sclerosis (MS). The aim of this study was to analyze the possible association of two TLR9 single nucleotide polymorphisms (SNPs; rs352162 and rs187084) with susceptibility to MS.

METHODS

Two independent cohorts of MS patients and controls were included: 574 clinically definite relapsing-remitting MS patients (367 females) and 807 healthy controls (418 females) for the first cohort; and 366 relapsing-remitting MS patients (238 females) and 224 healthy controls (160 females) for the second cohort. Genotyping was performed by TaqMan assays.

RESULTS

The AT haplotype was found to be significantly higher in women than in men (P = 0.013 and P = 0.044).

CONCLUSIONS

Here two possible genetic markers are proposed that could be also associated with the differences observed in the clinical course of MS in both genders. Further studies with larger cohorts should be performed to confirm these results.

Expression of human endogenous retrovirus HERV-K18 is associated with clinical severity in osteoarthritis patients

OBJECTIVES

The aim of this study was to evaluate the involvement of human endogenous retrovirus K18 (HERV-K18) in osteoarthritis (OA), by genotyping the HERV-K18 env locus in OA patients and controls, and analysing HERV-K18 RNA expression and its association with OA risk and clinical variables.

METHOD

We recruited 558 patients with symptomatic OA and 600 controls. We performed the genotyping by TaqMan assays and the analysis of expression by quantitative real-time polymerase chain reaction (qRT-PCR). Scores on the Western Ontario and McMasters Universities Osteoarthritis Index (WOMAC), the Lequesne index, and the Stanford Health Assessment Questionnaire (HAQ) were analysed with regard to the expression levels of HERV-K18.

RESULTS

The 18.3 haplotype tended towards an association with OA risk and concordantly this haplotype was associated with a higher HERV-K18 expression (p = 0.05). We found statistically significant differences when we compared the scores on the WOMAC, the Lequesne index for knee and hip, and the HAQ between OA patients with higher expression [normalization ratio (NR) > 10] and OA patients without HERV-K18 expression (p = 0.0003, 0.0005, 0.002, and 0.05, respectively), and also when the comparison was made between OA patients with higher expression (NR > 10) and OA patients with low expression of HERV-K18 (NR = 1) for the WOMAC and the Lequesne index for knee and hip (p = 0.002, 0.013, and 0.006, respectively).

CONCLUSIONS

We found an association between health status measurement systems and severity index for OA and the levels of expression of HERV-K18. These results suggest the possible involvement of HERV-K18 in the aetiopathogenesis of the disease.

Molecular characteristics of Human Endogenous Retrovirus type-W in schizophrenia and bipolar disorder

Epidemiological and genome-wide association studies of severe psychiatric disorders such as schizophrenia (SZ) and bipolar disorder (BD), suggest complex interactions between multiple genetic elements and environmental factors. The involvement of genetic elements such as Human Endogenous Retroviruses type 'W' family (HERV-W) has consistently been associated with SZ. HERV-W envelope gene (env) is activated by environmental factors and encodes a protein displaying inflammation and neurotoxicity. The present study addressed the molecular characteristics of HERV-W env in SZ and BD. Hundred and thirty-six patients, 91 with BD, 45 with SZ and 73 healthy controls (HC) were included. HERV-W env transcription was found to be elevated in BD (P<10-4) and in SZ (P=0.012) as compared with HC, but with higher values in BD than in SZ group (P<0.01). The corresponding DNA copy number was paradoxically lower in the genome of patients with BD (P=0.0016) or SZ (P<0.0003) than in HC. Differences in nucleotide sequence of HERV-W env were found between patients with SZ and BD as compared with HC, as well as between SZ and BD. The molecular characteristics of HERV-W env also differ from what was observed in Multiple Sclerosis (MS) and may represent distinct features of the genome of patients with BD and SZ. The seroprevalence for Toxoplasma gondii yielded low but significant association with HERV-W transcriptional level in a subgroup of BD and SZ, suggesting a potential role in particular patients. A global hypothesis of mechanisms inducing such major psychoses is discussed, placing HERV-W at the crossroads between environmental, genetic and immunological factors. Thus, particular infections would act as activators of HERV-W elements in earliest life, resulting in the production of an HERV-W envelope protein, which then stimulates pro-inflammatory and neurotoxic cascades. This hypothesis needs to be further explored as it may yield major changes in our understanding and treatment of severe psychotic disorders.

Influence of metyrapone treatment during pregnancy on the development and maturation of brain monoaminergic systems in the rat

AIM

This study examines the effect of reducing the corticosterone levels of gestating rat dams on the postnatal development and maturation of monoaminergic systems in their offspring's brains.

METHODS

Metyrapone, an inhibitor of CORT synthesis, was administered to pregnant rats from E0 to E17 of gestation. Monoamine concentrations were determined in male and female offspring at postnatal days (PN) 23 and 90 in the hippocampus, hypothalamus and striatum.

RESULTS

Reducing maternal corticosterone (mCORT) during gestation led to alterations in dopamine and serotonin levels in all three brain areas studied at PN 23. Alterations persisted until at least PN 90 in the serotonergic systems; the dopamine content of the hippocampus also remained modified. Reduced mCORT during gestation also led to alterations in the development and maturation of the hypothalamic noradrenergic systems. Sexually dimorphic responses were observed in all these monoaminergic systems at different times.

CONCLUSION

These results suggest that while they are still developing, brain monoaminergic systems are particularly sensitive to epigenetic influences. An adequate foetal level of CORT is required for the normal ontogeny of brain monoaminergic systems. The present data also provide that during the critical period of brain development, maternal CORT plays an important role in the sexual differentiation of monoaminergic systems, with particular influence on brain serotonergic neurones.

CD46 expression and HHV-6 infection in patients with multiple sclerosis

OBJECTIVES

The aim of this study was to investigate the possible association between the levels of the CD46 expression, and the presence and viral load of HHV-6 in patients with multiple sclerosis (MS).

METHODS

We collected blood and serum samples of 103 patients with MS and the same number of healthy blood donors (HBD); total DNA and RNA was extracted from peripheral blood mononuclear cells (PBMCs) and serum, and then analyzed using quantitative real-time PCR for the detection of CD46 transcripts and HHV-6 genomes; the expression of rRNA18s was used for the calculation of the relative expression of CD46.

RESULTS

Almost 80% of patients with MS had increased levels of CD46 in comparison with HBD, and a positive correlation was also found between the over-expression of CD46 in patients with MS and the HHV-6 DNA prevalence and viral load in the blood and serum.

DISCUSSION

Therefore, the up-regulation of CD46 expression in patients with MS with HHV-6 infection could constitute an immunopathogenic factor that should be further investigated to elucidate its role in MS.

MHC2TA rs4774C and HHV-6A active replication in multiple sclerosis patients

BACKGROUND AND PURPOSE

In a previous report, a strong gene-environment interaction between human herpesvirus 6A (HHV6A) active replication and MHC2TA rs4774C was demonstrated. The objectives of this study were: (i) to reappraise the association that was found in the previous study; (ii) to evaluate if MS patients with minor allele C and HHV-6A active infection had different clinical behavior; and (iii) to analyze the possible association of MHC2TA rs4774C with Epstein-Barr virus (EBV).

METHODS

A total of 149 MS patients were analyzed both at the MHC2TA locus and by HHV-6A status in serum. We studied a G/C polymorphism (rs4774) by a TaqMan Assay-on-Demand. HHV-6A genomes in serum were evaluated by quantitative PCR. A control group of 562 healthy Spanish individuals was included for comparative purposes in the genetic analyses. A battery of clinical data was collected for all the MS patients included in the study.

RESULTS

(i) MHC2TA/HHV-6A interaction: we found the same strong association of the rs4774C allele with HHV-6A active replication than in the previous study (P = 0.0001). (ii)

CLINICAL DATA

the two main statistical significant differences for MS patients with HHV-6A active infection and minor allele C were: (a) a significant number of them were not free of progression (EDSS = 0) 2 years after the diagnosis (P = 0.01); (b) only a third of them responded to interferon beta treatment (P = 0.05).

CONCLUSIONS

This study has verified previous results about the strong gene-environment interaction between HHV6A active replication and MHC2TA rs4774C. Furthermore, a different clinical behavior for MS patients with HHV-6A active infection and minor allele C was found.