The role of non-HLA single nucleotide polymorphisms in multiple sclerosis susceptibility

Expression Analysis of Long Non-coding RNA Lnc-DC in HLA-DRB1*15:01-Negative Patients with Multiple Sclerosis: A Probable Cause for Gender Differences in Multiple Sclerosis Susceptibility?

Multiple sclerosis is a disease that affects male and female patients differently. Several studies have been performed to explain the gender differences in MS susceptibility, but the genetic causes underlying gender differences remain unknown. The association between multiple sclerosis and the HLA-DRB1*15:01 haplotype has been confirmed to be female-specific. We hypothesized other immunological components such as lnc-DC may be gender-specific among multiple sclerosis patients, especially when MS patients are negative for the HLA-DRB1*15:01 allele. Therefore, the current study, considering the results of previous studies, aimed to evaluate the expression level of the lnc-DC gene in HLA-DRB1*15:01-negative female patients with relapsing remitting MS (RRMS). A total of 50 MS female patients and 50 female healthy controls were enrolled in this observational case-control study. HLA-DRB1*15:01, as a critical risk factor for MS, was ruled out in all patients. The peripheral blood mononuclear cells were obtained from all patients and total RNA was isolated and cDNA synthesis was carried out. The gene expression of lnc-DC was evaluated by real-time quantitative PCR. Our results have shown that lnc-DC expression level was significantly higher in total MS female patients compared with female controls (P = 0.0044). In addition, the correlation between lnc-DC with disease duration, EDSS, and age at onset did not reach a statistical significance in our study (r = 0.0336, P = 0.817; r = 0.0914, P = 0.5278 and r = 0.0743, P = 0.6083, respectively). Our results give further evidence that lnc-DC may play a gender-dependent role in MS pathogenesis.

High-resolution melting curve analysis of polymorphisms within CD58, CD226, HLA-G genes and association with multiple sclerosis susceptibility in a subset of Iranian population: a case-control study

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system with unknown etiology, which typically is manifested in early to middle adulthood. Recently, genome-wide association studies have identified susceptibility of immune-related genes to be involved in MS predisposition. The goal of the current study was to investigate the association of single nucleotide polymorphisms (SNP) with the immunologically related genes responsible for the disease, composed of CD58 (rs2300747 A>G), CD226 (rs763361 C>T), and HLA-G (rs1611715 A>C), with MS susceptibility. In this case-control study, a total of 200 patients suffering from relapsing-remitting multiple sclerosis and 200 healthy individuals were recruited. DNA was extracted from blood and then all subjects were genotyped for the polymorphism within mentioned genes by high-resolution melting (HRM) real-time PCR method. Statistical analyses were performed using SPSS software (version 20; SPSS, Chicago, IL, USA). Our finding showed that there are significant differences in genotype and allele frequencies between two groups regarding rs763361 (P = 0.035, OR 0.64, CI 95% for C allele) and rs1611715 (P = 0.038, OR 1.57, CI 95% for AA genotype) polymorphisms within CD226 and HLA-G genes, respectively. Concerning rs2300747 polymorphism on CD58 gene, no significant differences were found between cases and controls. In general, results from the current study indicate that CD226 and HLA-G, but not CD58 genetic polymorphisms are associated with increased risk of MS in Isfahan population similar to European populations. However, to elucidate how these SNPs contribute to MS pathogenesis, functional studies are needed.

Association of CD58 polymorphism and multiple sclerosis in Malaysia: a pilot study

Background

Multiple sclerosis is an immune mediated disease targeting the central nervous system. Association of non-human leukocyte antigen gene, CD58, with multiple sclerosis has been reported in several populations but is unclear among Southeast Asians. This pilot study was conducted to explore the association between CD58 polymorphism and multiple sclerosis among the Malay population in Malaysia.

Methods

Blood samples were collected from 27 multiple sclerosis patients, and compared with 58 age- and gender matched healthy individuals. All patients were tested negative for anti-aquaporin 4. DNA was extracted from the blood and genotyped for 3 single nucleotide polymorphisms rs12044852, rs2300747 and rs1335532 of gene CD58 by real-time PCR.

Results

The majority of multiple sclerosis patients were female (85.2%). The general mean age of onset was 30.5 years. Genotyping results showed that frequencies of the alleles were between 40 and 50% for MS patients and healthy individuals. Association (allelic model) between multiple sclerosis and CD58 gene polymorphism alleles rs12044852 (p = 0.410), rs2300747 (p = 0.881) and rs1335532 (p = 0.407) were indistinct.

Conclusions

The impact of the CD58 gene polymorphism was not prominent in this pilot study, implying that genetic composition contributing to multiple sclerosis may be different between different populations, thus results in a heterogeneity of disease manifestation and distribution.

Complete sequence analysis of human toll-like receptor 3 gene in natural killer cells of multiple sclerosis patients

BACKGROUND

Multiple sclerosis (MS) is a chronic demyelinating disease of the central nervous system (CNS) where both environmental and genetic risk factors play a role. Among the environmental risk factors, EBV and HSV infections have been suggested as strong candidates contributing to MS pathology/progression. Viral recognition and control is largely tasked to the NK cells via TLR recognition and various cytotoxic and immunoregulatory functions. The present work aimed to characterize NK cells isolated from MS patients for genetic polymorphisms in the gene encoding for TLR3, as TLR3 in NK cells is important in herpesvirus recognition.

METHODS

Highly purified NK cells isolated from peripheral blood of MS patients (n = 27) and healthy controls (n = 30) were used to sequence all five exons of the TLR3 gene using sanger sequencing. Alignment of the obtained sequences with the wild-type TLR3 sequence was used to identify genetic polymorphisms within the TLR3 gene.

RESULTS

The alignment identified multiple substitution mutations across the five exons of the TLR3 gene (rs116729895, rs3775296, rs377529, rs3775290, rs3775291, rs376735334 and rs73873710). A significant difference was observed in the allele distribution of rs3775291 (Leu412Phe) between MS patients and HC, whereby the minor allele was detected in 38.9% of MS patients versus 11% of HC (Fisher's exact test, p = 0.021).

CONCLUSION

There appears to be a possible association between the TLR3 missense mutation rs3775291 and multiple sclerosis, which might be attributed to changes in the TLR3 functional properties.

Do Human Endogenous Retroviruses Contribute to Multiple Sclerosis, and if So, How?

The gammaretroviral human endogenous retrovirus (HERV) families MRSV/HERV-W and HERV-H (including the closely related HERV-Fc1) are associated with an increased risk of multiple sclerosis (MS). Complete HERV sequences betray their endogenous retroviral origin, with open reading frames in gag, pro, pol and env being flanked by two long terminal repeats containing promoter and enhancer sequences with the capacity to regulate HERV transactivation and the activity of host genes in spite of endogenous epigenetic repression mechanisms. HERV virions, RNA, cDNA, Gag and Env, and antibodies to HERV transcriptional products, have variously been found in the blood and/or brain and/or cerebrospinal fluid of MS patients, with the HERV expression level being associated with disease status. Furthermore, some HERV-associated single nucleotide polymorphisms (SNPs), such as rs662139 T/C in a 3-kb region of Xq22.3 containing a HERV-W env locus, and rs391745, upstream of the HERV-Fc1 locus on the X chromosome, are associated with MS susceptibility, while a negative association has been reported with SNPs in the tripartite motif-containing (TRIM) protein-encoding genes TRIM5 and TRIM22. Factors affecting HERV transcription include immune activation and inflammation, since HERV promoter regions possess binding sites for related transcription factors; oxidative stress, with oxidation of guanine to 8-oxoguanine and conversion of cytosine to 5-hydroxymethylcytosine preventing binding of methyl groups transferred by DNA methyltransferases; oxidative stress also inhibits the activity of deacetylases, thereby favouring the acetylation of histone lysine residues favouring gene expression; interferon beta; natalizumab treatment; impaired epigenetic regulation; and the sex of patients.

Analysis of MMP2-1306C/T and TIMP2G-418C polymorphisms with relapsing remitting multiple sclerosis

AIMS

Multiple sclerosis (MS) is an autoimmune, inflammatory disease characterized by loss of myelin forming oligodendrocytes and changes in the blood-brain barrier. Matrix metalloproteinase (MMP) -2 and -9 are known to cause disruption of the blood-brain barrier, remodeling of the basal lamina, regeneration of axons, and remyelination in MS. The imbalance between MMPs and tissue inhibitor metalloproteinases (TIMPs) may lead to the emergence of pathological processes such as MS. The roles of MMP2-1306 C/T and TIMP2-418 G/C genetic variants in MS have not been studied before. We aimed to investigate whether MMP2-1306C/T and TIMP2-418 G/C gene variants are risk factors for patients with relapsing remitting multiple sclerosis (RRMS).

METHODS

The study included 102 RRMS and 102 healthy controls. Genomic DNA was extracted from peripheral leukocytes from ethylenediaminetetraacetic acid anticoagulated blood. Genotyping of the MMP2-1306C/T and TIMP2G-418C polymorphisms was performed using real-time PCR.

RESULTS

There were significant differences in terms of distribution of genotype (MMP2-1306- CT, TT) and T allele frequency between the patients with RRMS and the control group (p<0.0001; p<0.0001). The groups were not different in terms of TIMP2G-418C polymorphisms.

CONCLUSIONS

In the RRMS group, the genotype and allele frequencies of MMP2-1306C/T polymorphism showed significant differences from the controls. These results indicate that MMP2 might play a role in the pathogenesis of MS even during the inflammation stage.

Age- and gender-specific effects on VDR gene polymorphisms and risk of the development of multiple sclerosis in Tunisians: a preliminary study

The vitamin D receptor (VDR) polymorphisms have been reported to be associated with multiple sclerosis (MS); however, evidence remains conflicting. In this report, we investigated the association between two single nucleotide polymorphisms (SNPs) TaqI and ApaI of VDR gene and risk development of MS. TaqI and ApaI SNPs were detected by PCR-RFLP from the DNA of 60 Tunisian patients with MS and 114 healthy controls. Our results show a significant difference of the allelic frequency distribution between the case and control groups for TaqI SNP (P = 0.01), but genotype frequencies were not significantly different (P = 0.07 and 0.23). When adjusting frequency distribution of different alleles and genotypes by age, we found that the difference between the T allele frequencies of this SNP in the group of patients age [15-24] in comparison with the control group of the same age group was statistically significant (P = 0.026). Moreover, frequency of the T allele was significantly higher in male patients compared with controls of the same sex (P = 0.017). However, neither the genotype nor the allele frequency distribution was significantly different between the MS and control populations for the ApaI SNP. Our preliminary results indicate that VDR gene polymorphism could be associated with susceptibility to MS. The role of VDR gene polymorphism should be further studied in other large populations, and the distribution of other polymorphism, such as FokI and BsmI, should be also analysed to confirm another susceptibility polymorphisms gene for MS and to obtain more adequate strategies for treatment of MS.

Cytokine profile in relapsing‑remitting multiple sclerosis patients and the association between progression and activity of the disease

Multiple sclerosis (MS) is a progressive immune‑ mediated disease caused by demyelination of the central nervous system. Cytokines and their receptors have an important role in the evolution of MS lesions, and pro‑ and anti‑inflammatory cytokine levels have been found to correlate with changes in MS disease activity. The aims of the present study were to evaluate the pro‑inflammatory [tumor necrosis factor (TNF)‑α and interleukin (IL) ‑1β, ‑6 and ‑12], T helper (Th) 1 [interferon (IFN)‑γ], Th17 (IL‑17) and Th2 (IL‑4 and ‑10) cytokine serum levels in relapsing‑remitting (RR)‑MS patients and to evaluate the association between the cytokine profile and the progression and activity of the disease. Serum cytokine levels were assessed using enzyme linked‑immunosorbent assays in 169 RR‑MS patients in the remission clinical phase and 132 healthy individuals who were age‑, gender‑, ethnicity‑ and body mass index‑matched. Disability and activity of the disease were evaluated using the Expanded Disability Status Scale and magnetic resonance imaging with gadolinium, respectively. IFN‑γ and IL‑6, ‑12 and ‑4 levels were higher in RR‑MS patients compared to controls (P=0.0009, 0.0114, 0.0297 and 0.0004, respectively). IL‑1 levels were higher in controls compared with RR‑MS patients. IL‑4 levels were higher in RR‑MS patients with mild disability compared to those with moderate and severe disability (P=0.0375). TNF‑α and IL‑10 levels were higher in RR‑MS patients with inactive disease compared with those with active disease. IL‑17 levels showed a trend towards being higher in RR‑MS patients with inactive disease compared to those with active disease (P=0.0631). Low TNF‑α and high IFN‑γ levels were independently associated with RR‑MS (P=0.0078 and 0.0056, respectively) and also with the activity of the disease (P=0.0348 and 0.0133, respectively). Results indicated that RR‑MS patients, even in the remission clinical phase, exhibit a complex system of inflammatory and anti‑inflammatory cytokines that may interact to modulate the progression and activity of the disease.

Polymorphisms in the vitamin D receptor gene and multiple sclerosis risk: a meta-analysis of case-control studies

BACKGROUND

The vitamin D receptor (VDR) polymorphisms have been reported to be associated with multiple sclerosis (MS), however, evidence remains conflicting. A meta-analysis was conducted to investigate this association.

METHODS

We searched Pubmed, Medline and Embase databases for case-control studies evaluating the association between the VDR Apa-I, Bsm-I, Fok-I, Taq-I polymorphisms and MS risk. Data were extracted using standardized forms and odds ratios (OR) with 95% confidence intervals (CI) were calculated.

RESULTS

11 case-control studies involving a total of 2599 cases and 2816 controls were included in this meta-analysis. Available data did not suggest an association between any of the VDR polymorphisms and the risk for MS. For Taq-I, which is the most investigated VDR polymorphism with 8 studies (2472 cases and 2446 controls), the combined OR was 1.12 (95% CI: 1.00-1.26) for the dominant model (tt+Tt vs. TT), 1.03(95% CI: 0.88-1.20) for the recessive model (tt vs. Tt+TT), and 1.04 (95% CI: 0.78-1.38) for the homozygote model (tt vs. TT). ORs for other VDR polymorphisms were similar.

CONCLUSION

The VDR Apa-I, Bsm-I, Fok-I and Taq-I polymorphisms are not associated with MS risk.

Interleukin 2 Receptor α Gene Polymorphism and Risk of Multiple Sclerosis: A Meta-Analysis

This meta-analysis studied the association between interleukin 2 receptor a (IL2RA) gene polymorphisms rs2104286 and rs12722489 and susceptibility to multiple sclerosis (MS). Case-control genetic association studies published before January 2011 were retrieved from the PubMed and EMBASE databases and the Cochrane Library. Eight studies comprising 13 569 patients and 23 435 controls met the selection criteria for meta-analysis of the IL2RA rs2104286 polymorphism. Using a fixed-effects model, the T allele and the TT and TT + TC genotypes of the IL2RA rs2104286 polymorphism were found to be associated with MS. Five studies comprising 5643 patients and 6415 controls met the selection criteria for meta-analysis of the IL2RA rs12722489 polymorphism. Using a fixed-effects model, the C allele and the CC genotype of the IL2RA rs12722489 polymorphism were found to be associated with MS but the CC + CT genotype was not. It was concluded that both of the IL2RA gene polymorphisms, rs2104286 and rs12722489, were associated with increased susceptibility to MS.

Insight from genome-wide association studies in rheumatoid arthritis and multiple sclerosis

Autoimmune diseases are caused by multiple genes and environmental effects. In addition, genetic contributions and the number of associated genes differ among different diseases and ethnic populations. Genome-wide association studies (GWAS) on rheumatoid arthritis (RA) and multiple sclerosis (MS) show that these diseases share many genetic factors. Recently, in addition to the major histocompatibility complex (MHC) gene, other genetic loci have been found to be associated with the risk for autoimmune diseases. This review focuses on the search for genetic variants that influence the susceptibility to RA and MS as typical autoimmune diseases and discusses the future of GWAS.

-308 G > A of TNF-α gene promoter decreases the risk of multiple sclerosis: a meta-analysis

BACKGROUND

Environmental and genetic factors are thought to be involved in the pathogenesis of multiple sclerosis (MS). Polymorphisms of tumor necrosis factor (TNF)-α -308 were implicated in MS risk in several case-control association studies. However, the studies have shown inconsistent results.

OBJECTIVES

To address the association of G/A polymorphisms of TNF-α -308 with MS risk by meta-analysis.

METHODS

Thirteen studies were included. Pooled odds ratios (ORs) together with 95% confidence intervals (CIs) were calculated.

RESULTS

A total of 1870 cases and 2769 controls were included in the meta-analysis. The pooled result indicated that -308 A allele is significantly associated with reduced risk of MS compared with -308 G allele (A vs. G, p=0.022). The same pattern of the result was also obtained in the contrasts of AA+ GA vs. GG (p=0.008) and GA vs. GG (p=0.007). For AA vs. GG or AA vs. GA + GG, no significant association was detected most likely caused by very low frequency or non-availability of homozygote genotype AA for all of the studies.

CONCLUSIONS

TNF-α -308 A allele is associated with reduced risk of MS.