Multiple sclerosis and the major histocompatibility complex

Learning epistatic polygenic phenotypes with Boolean interactions

Detecting epistatic drivers of human phenotypes is a considerable challenge. Traditional approaches use regression to sequentially test multiplicative interaction terms involving pairs of genetic variants. For higher-order interactions and genome-wide large-scale data, this strategy is computationally intractable. Moreover, multiplicative terms used in regression modeling may not capture the form of biological interactions. Building on the Predictability, Computability, Stability (PCS) framework, we introduce the epiTree pipeline to extract higher-order interactions from genomic data using tree-based models. The epiTree pipeline first selects a set of variants derived from tissue-specific estimates of gene expression. Next, it uses iterative random forests (iRF) to search training data for candidate Boolean interactions (pairwise and higher-order). We derive significance tests for interactions, based on a stabilized likelihood ratio test, by simulating Boolean tree-structured null (no epistasis) and alternative (epistasis) distributions on hold-out test data. Finally, our pipeline computes PCS epistasis p-values that probabilisticly quantify improvement in prediction accuracy via bootstrap sampling on the test set. We validate the epiTree pipeline in two case studies using data from the UK Biobank: predicting red hair and multiple sclerosis (MS). In the case of predicting red hair, epiTree recovers known epistatic interactions surrounding MC1R and novel interactions, representing non-linearities not captured by logistic regression models. In the case of predicting MS, a more complex phenotype than red hair, epiTree rankings prioritize novel interactions surrounding HLA-DRB1, a variant previously associated with MS in several populations. Taken together, these results highlight the potential for epiTree rankings to help reduce the design space for follow up experiments.

Treatable Ataxias: How to Find the Needle in the Haystack?

Treatable ataxias are a group of ataxic disorders with specific treatments. These disorders include genetic and metabolic disorders, immune-mediated ataxic disorders, and ataxic disorders associated with infectious and parainfectious etiology, vascular causes, toxins and chemicals, and endocrinopathies. This review provides a comprehensive overview of different treatable ataxias. The major metabolic and genetic treatable ataxic disorders include ataxia with vitamin E deficiency, abetalipoproteinemia, cerebrotendinous xanthomatosis, Niemann-Pick disease type C, autosomal recessive cerebellar ataxia due to coenzyme Q10 deficiency, glucose transporter type 1 deficiency, and episodic ataxia type 2. The treatment of these disorders includes the replacement of deficient cofactors and vitamins, dietary modifications, and other specific treatments. Treatable ataxias with immune-mediated etiologies include gluten ataxia, anti-glutamic acid decarboxylase antibody-associated ataxia, steroid-responsive encephalopathy associated with autoimmune thyroiditis, Miller-Fisher syndrome, multiple sclerosis, and paraneoplastic cerebellar degeneration. Although dietary modification with a gluten-free diet is adequate in gluten ataxia, other autoimmune ataxias are managed by short-course steroids, plasma exchange, or immunomodulation. For autoimmune ataxias secondary to malignancy, treatment of tumor can reduce ataxic symptoms. Chronic alcohol consumption, antiepileptics, anticancer drugs, exposure to insecticides, heavy metals, and recreational drugs are potentially avoidable and treatable causes of ataxia. Infective and parainfectious causes of cerebellar ataxias include acute cerebellitis, postinfectious ataxia, Whipple's disease, meningoencephalitis, and progressive multifocal leukoencephalopathy. These disorders are treated with steroids and antibiotics. Recognizing treatable disorders is of paramount importance when dealing with ataxias given that early treatment can prevent permanent neurological sequelae.

p38 MAP Kinase Signaling in Microglia Plays a Sex-Specific Protective Role in CNS Autoimmunity and Regulates Microglial Transcriptional States

Multiple sclerosis (MS) is an autoimmune demyelinating disease of the central nervous system, representing the leading cause of non-traumatic neurologic disease in young adults. This disease is three times more common in women, yet more severe in men, but the mechanisms underlying these sex differences remain largely unknown. MS is initiated by autoreactive T helper cells, but CNS-resident and CNS-infiltrating myeloid cells are the key proximal effector cells regulating disease pathology. We have previously shown that genetic ablation of p38α MAP kinase broadly in the myeloid lineage is protective in the autoimmune model of MS, experimental autoimmune encephalomyelitis (EAE), but only in females, and not males. To precisely define the mechanisms responsible, we used multiple genetic approaches and bone marrow chimeras to ablate p38α in microglial cells, peripheral myeloid cells, or both. Deletion of p38α in both cell types recapitulated the previous sex difference, with reduced EAE severity in females. Unexpectedly, deletion of p38α in the periphery was protective in both sexes. In contrast, deletion of p38α in microglia exacerbated EAE in males only, revealing opposing roles of p38α in microglia vs. periphery. Bulk transcriptional profiling revealed that p38α regulated the expression of distinct gene modules in male vs. female microglia. Single-cell transcriptional analysis of WT and p38α-deficient microglia isolated from the inflamed CNS revealed a diversity of complex microglial states, connected by distinct convergent transcriptional trajectories. In males, microglial p38α deficiency resulted in enhanced transition from homeostatic to disease-associated microglial states, with the downregulation of regulatory genes such as Atf3, Rgs1, Socs3, and Btg2, and increased expression of inflammatory genes such as Cd74, Trem2, and MHC class I and II genes. In females, the effect of p38α deficiency was divergent, exhibiting a unique transcriptional profile that included an upregulation of tissue protective genes, and a small subset of inflammatory genes that were also upregulated in males. Taken together, these results reveal a p38α-dependent sex-specific molecular pathway in microglia that is protective in CNS autoimmunity in males, suggesting that autoimmunity in males and females is driven by distinct cellular and molecular pathways, thus suggesting design of future sex-specific therapeutic approaches.

Multiple sclerosis and immune system biomarkers: Novel comparison in glatiramer acetate and interferon beta-1a-treated patient groups

BACKGROUND

Multiple sclerosis (MS) is a chronic, demyelinating disease of the central nervous system (CNS). T cells and B lymphocytes are involved in the development of this disease.

METHODS

The following biomarkers were determined in peripheral blood in 28 patients treated with glatiramer acetate (GA) and 21 patients treated with interferon beta 1-a (IFN): IL-10, BAFF, Mx1, IgG, IgG1, IgG2, IgG3 and IgG4 (at baseline and after 6 months of treatment). All participants had confirmed MS diagnosis.

OBJECTIVES

The primary objective is to assess a percentual change of biomarkers after 6 months since the first-line treatment initiation with GA or IFN. The secondary objective is to explore correlations between the baseline biomarkers' values (levels).

RESULTS

A positive trend was observed in the increase in IL-10 concentration by 30.33 % (IFN) and by 15.65 % (GA). In the IFN group, we observed a statistically significant increase in the BAFF protein concentration by 29.9% (P < 0.001). We found that Mx1 protein levels did not change with the administration of GA, which can be explained by the different mechanisms of action of GA. The serum levels of IgG immunoglobulins and both IgG1 and IgG4 subclasses in both groups of patients were increased. Thus, our data were in accordance with the generally accepted assumption that both IFN and GA are capable of modulating the B cell system.

CONCLUSIONS

Our results suggest that treatment with IFN and GA has a more pronounced influence on the B cell system of MS.

TRAILR1 (rs20576) and GRIA3 (rs12557782) are not associated with interferon-β response in multiple sclerosis patients

Multiple sclerosis (MS) is an autoimmune-type inflammatory disorder in human central nervous system. Recombinant interferon beta (IFN-β) decreases the number of relapses and postpones disability progression in MS. However, up to 50% of patients treated with interferon beta continue experiencing relapses and/or worsening disability. Single nucleotide polymorphisms in different genes have been known to show significant associations with response to IFN-β in MS patients. In the present work, we examined the potential role of TRAILR1 and GRIA3 genes polymorphisms on response to IFN-β therapy in Iranian MS patients. The DNA was extracted from blood samples by standard procedures from 73 patients diagnosed with Multiple Sclerosis that were either responded to IFN-β or did not. We carried out RFLP -PCR and tetra-primer ARMS-PCR methods to study of rs20576 and rs12557782, respectively. All results were analyzed using the SPSS software. TRAILR1 rs20576 genotype frequencies in responders and non-responders were similar (χ² = 0.26, P = 0.87, Fisher^, s Exact test). Our results showed that response to IFN-β has not association with sex (p = 0.73). Also, genotypic frequencies of GRIA3 rs12557782 had no significant differences between two groups of female population (χ² = 3.75, p = 0.15). Furthermore, it had not been any statistical differences between responder and non-responder males (χ² = 0.7, p = 0.4) related to the SNP. Our results analysis revealed no significant association between the studied SNPs (TRAILR1 rs20576 and GRIA3rs 12,557,782) and response to IFN-β in Iranian MS patients.

Two genetic variants explain the association of European ancestry with multiple sclerosis risk in African-Americans

Epidemiological studies have suggested differences in the rate of multiple sclerosis (MS) in individuals of European ancestry compared to African ancestry, motivating genetic scans to identify variants that could contribute to such patterns. In a whole-genome scan in 899 African-American cases and 1155 African-American controls, we confirm that African-Americans who inherit segments of the genome of European ancestry at a chromosome 1 locus are at increased risk for MS [logarithm of odds (LOD) = 9.8], although the signal weakens when adding an additional 406 cases, reflecting heterogeneity in the two sets of cases [logarithm of odds (LOD) = 2.7]. The association in the 899 individuals can be fully explained by two variants previously associated with MS in European ancestry individuals. These variants tag a MS susceptibility haplotype associated with decreased CD58 gene expression (odds ratio of 1.37; frequency of 84% in Europeans and 22% in West Africans for the tagging variant) as well as another haplotype near the FCRL3 gene (odds ratio of 1.07; frequency of 49% in Europeans and 8% in West Africans). Controlling for all other genetic and environmental factors, the two variants predict a 1.44-fold higher rate of MS in European-Americans compared to African-Americans.

MHC Class II (DRB) Promoter Polymorphism and Its Role in Parasite Control among Malaria Patients

MHC class II (MHCII) molecules are cell surface glycoproteins that play an important role to develop adaptive immune responses. MHCII-disease association is not restricted to structural variation alone but also may extend to genetic variations, which may modulate gene expression. The observed variations in class II gene expression make it possible that the association of MHCII polymorphism with diseases may relate to the level of gene expression in addition to the restriction of response to Ag. Understanding the extent of, and the mechanisms underlying, transcription factor DNA binding variation is therefore key to elucidate the molecular determinants of complex phenotypes. In this study, we investigated whether single nucleotide polymorphisms in MHCII-DRB regulatory gene may be associated with clinical outcomes of malaria in Plasmodium-infected individuals. To this end, we conducted a case-control study to compare patients who had mild malaria with those patients who had asymptomatic Plasmodium infection. It demonstrates that GTAT haplotype exerts an increased DRB transcriptional activity, resulting in higher DRB expression and subsequently perturbed Ag presentation and T cell activation, higher TLR-mediated innate immune gene expression, and Ag clearance, so low parasitemia in comparison with haplotypes other than GTAT (GTAC, GGGT). Hence, we hypothesized that DRB gene promoter polymorphism might lead to altered DRB gene expression, which could possibly affect the TLR-triggered innate immune responses in malaria patients. These genetic findings may contribute to the understanding of the pathogenesis of malaria and will facilitate the rational vaccine design for malaria.

Next-generation sequencing identifies contribution of both class I and II HLA genes on susceptibility of multiple sclerosis in Japanese

Background

The spectrum of classical and non-classical HLA genes related to the risk of multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) in the Japanese population has not been studied in detail. We conducted a case-control analysis of classical and non-classical HLA genes.

Methods

We used next-generation sequencing (NGS)-based HLA genotyping methods for mapping risk for 45 MS patients, 31 NMOSD patients, and 429 healthy controls. We evaluated the association of the HLA variants with the risk of MS and NMOSD using logistic regression analysis and Fisher’s exact test.

Results

We confirmed that HLA-DRB1*15:01 showed the strongest association with MS (P = 2.1 × 10⁻⁵; odds ratio [OR] = 3.44, 95% confidence interval [95% CI] = 1.95–6.07). Stepwise conditional analysis identified HLA-DRB1*04:05, HLA-B*39:01, and HLA-B*15:01 as being associated with independent MS susceptibility (P_Conditional < 8.3 × 10⁻⁴). With respect to amino acid polymorphisms in HLA genes, we found that phenylalanine at HLA-DQβ1 position 9 had the strongest effect on MS susceptibility (P = 3.7 × 10⁻⁸, OR = 3.48, 95% CI = 2.23–5.43). MS risk at HLA-DQβ1 Phe9 was independent of HLA-DRB1*15:01 (P_Conditional = 1.5 × 10⁻⁵, OR = 2.91, 95% CI = 1.79–4.72), while HLA-DRB1*15:01 was just significant when conditioned on HLA-DQβ1 Phe9 (P_Conditional = 0.037). Regarding a case-control analysis for NMOSD, HLA-DQA1*05:03 had a significant association with NMOSD (P = 1.5 × 10⁻⁴, OR = 6.96, 95% CI = 2.55–19.0).

Conclusions

We identified HLA variants associated with the risk of MS and NMOSD. Our study contributes to the understanding of the genetic architecture of MS and NMOSD in the Japanese population.

Electronic supplementary material

The online version of this article (10.1186/s12974-019-1551-z) contains supplementary material, which is available to authorized users.

Investigating multiple sclerosis genetic susceptibility on the founder population of east-central Sardinia via association and linkage analysis of immune-related loci

BACKGROUND

A wealth of single-nucleotide polymorphisms (SNPs) responsible for multiple sclerosis (MS) susceptibility have been identified; however, they explain only a fraction of MS heritability.

OBJECTIVES

We contributed to discovery of new MS susceptibility SNPs by studying a founder population with high MS prevalence.

METHODS

We analyzed ImmunoChip data from 15 multiplex families and 94 unrelated controls from the Nuoro Province, Sardinia, Italy. We tested each SNP for both association and linkage with MS, the linkage being explored in terms of identity-by-descent (IBD) sharing excess and using gene dropping to compute a corresponding empirical p-value. By targeting regions that are both associated and in linkage with MS, we increase chances of identifying interesting genomic regions.

RESULTS

We identified 486 MS-associated (p < 1 × 10-4) and 18,426 MS-linked (p < 0.05) SNPs. A total of 111 loci were both linked and associated with MS, 18 of them pointing to 14 non-major histocompatibility complex (MHC) genes, and 93 of them located in the MHC region.

CONCLUSION

We discovered new suggestive signals and confirmed some previously identified ones. We believe this to represent a significant step toward an understanding of the genetic basis of MS.

Elevated EBNA-1 IgG in MS is associated with genetic MS risk variants

Objective:

To assess whether MS genetic risk polymorphisms (single nucleotide polymorphism [SNP]) contribute to the enhanced humoral immune response against Epstein-Barr virus (EBV) infection in patients with MS.

Methods:

Serum anti-EBV nuclear antigen 1 (EBNA-1) and early antigen D (EA-D) immunoglobulin γ (IgG) levels were quantitatively determined in 668 genotyped patients with MS and 147 healthy controls. Anti–varicella-zoster virus (VZV) IgG levels were used as a highly prevalent, non-MS–associated control herpesvirus. Associations between virus-specific IgG levels and MS risk SNPs were analyzed.

Results:

IgG levels of EBNA-1, but not EA-D and VZV, were increased in patients with MS compared with healthy controls. Increased EBNA-1 IgG levels were significantly associated with risk alleles of SNP rs2744148 (SOX8), rs11154801 (MYB), rs1843938 (CARD11), and rs7200786 (CLEC16A/CIITA) in an interaction model and a trend toward significance for rs3135388 (HLA-DRB1*1501). In addition, risk alleles of rs694739 (PRDX5/BAD) and rs11581062 (VCAM1) were independently associated and interacted with normal EBNA-1 IgG levels. None of these interactions were associated with EA-D and VZV IgG titers.

Conclusions:

Several MS-associated SNPs significantly correlated with differential IgG levels directed to a latent, but not a lytic EBV protein. The data suggest that the aforementioned immune-related genes orchestrate the aberrant EBNA-1 IgG levels.

Genetic risk factors for pediatric-onset multiple sclerosis

BACKGROUND

Strong evidence supports the role of both genetic and environmental factors in pediatric-onset multiple sclerosis (POMS) etiology.

OBJECTIVE

We comprehensively investigated the association between established major histocompatibility complex (MHC) and non-MHC adult multiple sclerosis (MS)-associated variants and susceptibility to POMS.

METHODS

Cases with onset <18 years (n = 569) and controls (n = 16,251) were included from the United States and Sweden. Adjusted logistic regression and meta-analyses were performed for individual risk variants and a weighted genetic risk score (wGRS) for non-MHC variants. Results were compared to adult MS cases (n = 7588).

RESULTS

HLA-DRB1*15:01 was strongly associated with POMS (odds ratio (OR)_meta = 2.95, p < 2.0 × 10^-16). Furthermore, 28 of 104 non-MHC variants studied (23%) were associated (p < 0.05); POMS cases carried, on average, a higher burden of these 28 variants compared to adults (OR_avg = 1.24 vs 1.13, respectively), though the difference was not significant. The wGRS was strongly associated with POMS (OR_meta = 2.77, 95% confidence interval: 2.33, 3.32, p < 2.0 × 10^-16) and higher, on average, when compared to adult cases. Additional class III risk variants in the MHC region associated with POMS were revealed after accounting for HLA-DRB1*15:01 and HLA-A*02.

CONCLUSION

Pediatric and adult MS share many genetic variants suggesting similar biological processes are present. MHC variants beyond HLA-DRB1*15:01 and HLA-A*02 are also associated with POMS.

Pharmacogenetic Biomarkers to Predict Treatment Response in Multiple Sclerosis: Current and Future Perspectives

Disease-modifying therapies (DMTs) have significantly advanced the treatment of relapsing multiple sclerosis (MS), decreasing the frequency of relapses, disability, and magnetic resonance imaging lesion formation. However, patients' responses to and tolerability of DMTs vary considerably, creating an unmet need for biomarkers to identify likely responders and/or those who may have treatment-limiting adverse reactions. Most studies in MS have focused on the identification of pharmacogenetic markers, using either the candidate-gene approach, which requires prior knowledge of the genetic marker and its role in the target disease, or genome-wide association, which examines multiple genetic variants, typically single nucleotide polymorphisms (SNPs). Both approaches have implicated numerous alleles and SNPs in response to selected MS DMTs. None have been validated for use in clinical practice. This review covers pharmacogenetic markers in clinical practice in other diseases and then reviews the current status of MS DMT markers (interferon β, glatiramer acetate, and mitoxantrone). For a complex disease such as MS, multiple biomarkers may need to be evaluated simultaneously to identify potential responders. Efforts to identify relevant biomarkers are underway and will need to be expanded to all MS DMTs. These will require extensive validation in large patient groups before they can be used in clinical practice.

Variants in the IL7RA gene confer susceptibility to multiple sclerosis in Caucasians: evidence based on 9734 cases and 10436 controls

Recently, numerous genome wide association studies (GWAS) and other case-control association studies examining the relationship between interleukin-7 receptor α chain (IL7RA) gene rs3194051, rs987107, rs11567686, and rs11567685 variants and multiple sclerosis (MS) risk have been conducted, but the conclusions have been inconsistent. The main objective of this meta-analysis was to more precisely explore the association of these four IL7RA variants with MS development. Twenty-seven eligible studies involving 9734 cases and 10436 controls were included in the present meta-analysis. Power calculation, publication bias, sensitivity analysis and cumulative meta-analysis were performed to derive a reliable conclusion. Our study indicated three IL7RA loci were significantly associated with increasing MS risk (rs3194051: recessive model: OR = 1.22, 95% CI 1.08–1.38; rs987107: recessive model: OR = 1.44, 95% CI 1.22–1.69; and rs11567686: dominant model: OR = 1.18, 95% CI 1.01–1.37). Additionally, IL7RA rs11567685 variants might not be related to MS development. In all, IL7RA locus polymorphisms could play an important role in the predisposition to MS, which could contribute to a better understanding the pathogenesis of multiple sclerosis.

Clinical Application of Autologous Adipose Stem Cells in Patients with Multiple Sclerosis: Preliminary Results

The clinical outcome of autologous adipose stem cell (ASC) treatment of patients with multiple sclerosis (MS) was investigated following one year of observation. Methods. The clinical and MRI outcomes of 16 ASC-treated patients with RRMS and SPMS are reported after a one-year follow-up period. Results. At 18 months of follow-up, some patients showed “enticing” improvements on some exploratory efficacy measures, although a significant benefit was not observed for any measure across the entire group. Neither the progression of disability nor relapses were observed in any cases. In four patients, we found new gadolinium+ (Gd+) lesions on MRI. Our results indicate that ASC therapy is safe and does not produce any substantial side effects. Disease progression-free survival (PFS) of 18 months was seen in all patients with RRMS and SPMS. In these patients, EDSS scores did not progress above baseline scores. Gd-enhancing lesions were observed in two cases with RRMS, but these patients did not exhibit changes in EDSS score. Conclusion. Intrathecal treatment with ASCs is an attractive form of therapy for patients with MS but should be reserved for cases with aggressive disease progression, for cases that are still in the inflammatory phase, and for the malignant form.

Follicular Helper T (Tfh) Cells in Autoimmune Diseases and Allograft Rejection

Production of high affinity antibodies for antigens is a critical component for the immune system to fight off infectious pathogens. However, it could be detrimental to our body when the antigens that B cells recognize are of self-origin. Follicular helper T, or Tfh, cells are required for the generation of germinal center reactions, where high affinity antibody-producing B cells and memory B cells predominantly develop. As such, Tfh cells are considered as targets to prevent B cells from producing high affinity antibodies against self-antigens, when high affinity autoantibodies are responsible for immunopathologies in autoimmune disorders. This review article provides an overview of current understanding of Tfh cells and discusses it in the context of animal models of autoimmune diseases and allograft rejections for generation of novel therapeutic interventions.

Association of EVI5 rs11808092, CD58 rs2300747, and CIITA rs3087456 polymorphisms with multiple sclerosis risk: A meta-analysis

Purpose

Multiple sclerosis (MS) is a major demyelinating disease of the central nervous system with a strong genetic component. Previous studies have reported that the association of EVI5 rs11808092, CD58 rs2300747, and CIITA rs3087456 polymorphisms with the susceptibility to MS. However, the results were inconsistent. Thus, we conducted this meta-analysis to provide a more accurate estimation of the association between any of these polymorphisms and MS risk.

Methods

The PubMed, Embase, Chinese National Knowledge Infrastructure, Wan Fang databases and MSGene were used to search all potentially relevant studies. The odds ratio (OR) with 95% confidence interval (CI) was used to investigate the associations between these three polymorphisms and MS risk.

Results

16 independent case–control studies from 12 publications were finally included into this meta-analysis. The results showed that EVI5 rs11808092 polymorphism was related with increasing the development of MS under five genetic models (allelic: OR = 1.17, 95% CI = 1.10–1.24, P < 0.01; homozygous: OR = 1.37, 95% CI = 1.18–1.59, P < 0.01; heterozygous: OR = 1.16, 95% CI = 1.07–1.26, P < 0.01; recessive: OR = 1.28, 95% CI = 1.11–1.48, P < 0.01; and dominant: OR = 1.19, 95% CI = 1.11–1.48, P < 0.01). CD58 rs2300747 polymorphism was found to be associated with decreasing MS risk in three genetic models (allelic: OR = 0.86, 95% CI = 0.78–0.94, P < 0.01; heterozygous: OR = 0.85, 95% CI = 0.76–0.94, P < 0.01, and dominant: OR = 0.84, 95% CI = 0.76–0.93, P < 0.01). However, this meta-analysis indicated that CIITA rs3087456 polymorphism was not related to multiple sclerosis.

Conclusions

The mutant alleles of EVI5 rs11808092 polymorphism may increase the susceptibility to MS while those of CD58 rs2300747 polymorphism may decrease MS risk. In addition, CIITA rs3087456 polymorphism might not be associated with MS.

Immunological Functions of the Membrane Proximal Region of MHC Class II Molecules

Major histocompatibility complex (MHC) class II molecules present exogenously derived antigen peptides to CD4 T cells, driving activation of naïve T cells and supporting CD4-driven immune functions. However, MHC class II molecules are not inert protein pedestals that simply bind and present peptides. These molecules also serve as multi-functional signaling molecules delivering activation, differentiation, or death signals (or a combination of these) to B cells, macrophages, as well as MHC class II-expressing T cells and tumor cells. Although multiple proteins are known to associate with MHC class II, interaction with STING (stimulator of interferon genes) and CD79 is essential for signaling. In addition, alternative transmembrane domain pairing between class II α and β chains influences association with membrane lipid sub-domains, impacting both signaling and antigen presentation. In contrast to the membrane-distal region of the class II molecule responsible for peptide binding and T-cell receptor engagement, the membrane-proximal region (composed of the connecting peptide, transmembrane domain, and cytoplasmic tail) mediates these "non-traditional" class II functions. Here, we review the literature on the function of the membrane-proximal region of the MHC class II molecule and discuss the impact of this aspect of class II immunobiology on immune regulation and human disease.

Overall conceptual framework for studying the genetics of autoimmune diseases following vaccination: a regulatory perspective

The US Vaccine Adverse Event Reporting System contains case reports of autoimmune diseases (ADs) occurring following vaccinations. ADs are rare and occur in unvaccinated people, making the potential association between vaccines and ADs challenging to evaluate. Developing mechanistic pathways that link genes, immune mediators, vaccine components and ADs would be helpful for hypothesis generation, enhancing theories of biologic plausibility and grouping rare autoimmune adverse events to increase the ability to detect and evaluate safety signals. Here, we propose a conceptual framework for investigating the genetics of ADs as safety signals following vaccination, potentially contributing to the identification of relevant biomarkers. We also discuss a study design that incorporates genetic information into postmarket clinical evaluation of autoimmune adverse events following vaccination.

Multiple sclerosis-associated CLEC16A controls HLA class II expression via late endosome biogenesis

C-type lectins are key players in immune regulation by driving distinct functions of antigen-presenting cells. The C-type lectin CLEC16A gene is located at 16p13, a susceptibility locus for several autoimmune diseases, including multiple sclerosis. However, the function of this gene and its potential contribution to these diseases in humans are poorly understood. In this study, we found a strong upregulation of CLEC16A expression in the white matter of multiple sclerosis patients (n = 14) compared to non-demented controls (n = 11), mainly in perivascular leukocyte infiltrates. Moreover, CLEC16A levels were significantly enhanced in peripheral blood mononuclear cells of multiple sclerosis patients (n = 69) versus healthy controls (n = 46). In peripheral blood mononuclear cells, CLEC16A was most abundant in monocyte-derived dendritic cells, in which it strongly co-localized with human leukocyte antigen class II. Treatment of these professional antigen-presenting cells with vitamin D, a key protective environmental factor in multiple sclerosis, downmodulated CLEC16A in parallel with human leukocyte antigen class II. Knockdown of CLEC16A in distinct types of model and primary antigen-presenting cells resulted in severely impaired cytoplasmic distribution and formation of human leucocyte antigen class II-positive late endosomes, as determined by immunofluorescence and electron microscopy. Mechanistically, CLEC16A participated in the molecular machinery of human leukocyte antigen class II-positive late endosome formation and trafficking to perinuclear regions, involving the dynein motor complex. By performing co-immunoprecipitations, we found that CLEC16A directly binds to two critical members of this complex, RILP and the HOPS complex. CLEC16A silencing in antigen-presenting cells disturbed RILP-mediated recruitment of human leukocyte antigen class II-positive late endosomes to perinuclear regions. Together, we identify CLEC16A as a pivotal gene in multiple sclerosis that serves as a direct regulator of the human leukocyte antigen class II pathway in antigen-presenting cells. These findings are a first step in coupling multiple sclerosis-associated genes to the regulation of the strongest genetic factor in multiple sclerosis, human leukocyte antigen class II.

The retrovirus/superantigen hypothesis of multiple sclerosis

The pathogenesis of multiple sclerosis (MS) is as yet unknown. Commonly, MS is assumed to be due to an autoimmune inflammation of the central nervous system (CNS). Neurodegeneration is regarded to be a secondary reaction. This concept is increasingly being challenged. Human endogenous retroviruses (HERV) that could be locally activated in the CNS have been proposed as an alternative concept. HERV-encoded envelope proteins (env) can act as strong immune stimulators (superantigens). Thus, slow disease progression following neurodegeneration might be induced by re-activation of HERV expression directly, while relapses in parallel to inflammation might be secondary to the expression of HERV-encoded superantigens. It has been shown previously that T-cell superantigens are capable to induce a cellular inflammatory reaction in the CNS of experimental animals similar to that in MS. Furthermore, B-cell superantigens have been shown to activate blood leucocytes in vitro to produce immunoglobulin in an oligoclonal manner. It remains to be established, whether the outlined hypothesis accords with all known features of MS. Furthermore, anti-HERV agents may be taken into consideration to enrich and improve MS therapy.

Gender and autoimmune comorbidity in multiple sclerosis

BACKGROUND

The female preponderance in incidence of multiple sclerosis (MS) calls for investigations into sex differences in comorbidity with other autoimmune diseases (ADs).

OBJECTIVES

To determine whether male and female patients with MS have a higher frequency of autoimmune comorbidity than controls, and to describe the type and frequency of ADs that are associated with MS.

METHODS

Our database was established by linkage of the Danish MS Registry to The Danish National Patient Register and consisted of 1403 patients of both sexes with clinical onset of MS between 2000 and 2004, and 25 matched controls for every case.

RESULTS

None of the ADs occurred more frequently in female cases than in controls. Male cases were more likely to have Type I diabetes mellitus (odds ratio (OR) = 3.34; 95% CI 1.40 - 7.02; p < 0.008), Crohn's disease (OR = 5.03; 95% CI 1.18 - 16.10; p = 0.03) and systemic lupus erythematosus (OR = 12.55; 95% CI 1.62 - 69.95; p = 0.02) than male controls.

CONCLUSIONS

Autoimmune disorders are rare, but some of them tend to occur together with MS at a higher rate than in controls. Although women are generally more prone to ADs than men, significantly increased occurrence of other ADs were only found in male MS patients.

Antigenic peptide molecular recognition by the DRB1–DQB1 haplotype modulates multiple sclerosis susceptibility

DRB1–DQB1 binding affinities in peptide molecular recognition process. (A) In protective haplotype DRB1 allele displays a preferential affinity for MBP peptide, while (B) in predisposing haplotype DQB1 allele displays a preferential affinity for EBNA1 peptide.

HHV-6 and Multiple Sclerosis

Multiple sclerosis (MS) is an inflammatory demyelinating disease affecting the central nervous system, thought to be an autoimmune disease mediated by autoreactive lymphocytes. The pathogenesis of MS is multifactorial and is thought to be triggered by multiple environmental factors in genetically susceptible individuals. Viruses have long been postulated as potential environmental triggers in MS, and there is increasing evidence of a link between viruses and MS. Some of the most compelling data have been found in human herpesvirus 6 (HHV-6) research. HHV-6 is a ubiquitous, neurotropic herpesvirus; HHV-6 DNA has been found in MS plaques compared to healthy brain tissue. Studies have also shown that MS patients have higher viral titers and higher DNA detection in serum and CSF compared to controls, and that the virus seems to be more actively replicating in MS patients. Potential mechanisms for HHV-6 leading to autoimmunity include molecular mimicry, bystander activation, and epitope spreading, among others.

The association of HLA-DRB1 alleles and drug use with HIV infection in a Chinese Han Cohort

Objective

To investigate the relationship between the polymorphism of human leukocyte antigen (HLA)-DRB1 and the susceptibility and repellency of drug use combined with HIV infection in Chinese.

Methods

A total of 213 unrelated healthy people, 41 HIV-infected drug users, 24 HIV-uninfected drug users, and 64 HIV-infected non-drug users were recruited. Their HLA-DRB1 allele frequencies were analyzed by PCR-SSP and allele distribution was analyzed.

Results

Compared with healthy controls, in drug users, the frequencies of HLA-DRB1 *0401-041, *1001 were significantly higher; in HIV-infected patients, the frequencies of HLA-DRB1 *0101-0103, *0401-0411, *1001 were significantly higher, while the frequencies of DRB1 *1501-1502, *1101-1105, *1301-1302, DRB4, DRB5 were significantly lower; in HIV-infected drug users, the frequencies of HLA-DRB1 *0101-0103, *0401-0411, *0801-0806, *1001, *1401/1404/1405 were significantly higher, while the frequencies of DRB1 *1301/1302, 1501-1502, DRB5 were significantly lower.

Conclusion

There is close relationship between the polymorphism of HLA-DRB1 alleles and drug use with HIV infection, which plays an important role in elucidating the pathogenesis and providing the basis for therapeutics and prophylaxis of patients with drug use and HIV infection.

Fine-mapping the genetic association of the major histocompatibility complex in multiple sclerosis: HLA and non-HLA effects

The major histocompatibility complex (MHC) region is strongly associated with multiple sclerosis (MS) susceptibility. HLA-DRB1*15:01 has the strongest effect, and several other alleles have been reported at different levels of validation. Using SNP data from genome-wide studies, we imputed and tested classical alleles and amino acid polymorphisms in 8 classical human leukocyte antigen (HLA) genes in 5,091 cases and 9,595 controls. We identified 11 statistically independent effects overall: 6 HLA-DRB1 and one DPB1 alleles in class II, one HLA-A and two B alleles in class I, and one signal in a region spanning from MICB to LST1. This genomic segment does not contain any HLA class I or II genes and provides robust evidence for the involvement of a non-HLA risk allele within the MHC. Interestingly, this region contains the TNF gene, the cognate ligand of the well-validated TNFRSF1A MS susceptibility gene. The classical HLA effects can be explained to some extent by polymorphic amino acid positions in the peptide-binding grooves. This study dissects the independent effects in the MHC, a critical region for MS susceptibility that harbors multiple risk alleles.

The emerging role of p38 mitogen-activated protein kinase in multiple sclerosis and its models

Multiple sclerosis (MS), the most common disabling neurologic disease of young adults, is considered a classical T cell-mediated disease and is characterized by demyelination, axonal damage, and progressive neurological dysfunction. The currently available disease-modifying therapies are limited in their efficacy, and improved understanding of new pathways contributing to disease pathogenesis could reveal additional novel therapeutic targets. The p38 mitogen-activated protein kinase (MAPK) signaling pathway is known to be triggered by stress stimuli and to contribute to inflammatory responses. Importantly, a number of recent studies have identified this signaling pathway as a central player in MS and its principal animal model, experimental allergic encephalomyelitis. Here, we review the evidence from mouse and human studies supporting the role of p38 MAPK in regulating key immunopathogenic mechanisms underlying autoimmune inflammatory disease of the central nervous system and the potential of targeting this pathway as a disease-modifying therapy in MS.

Identification of a functional variant in the KIF5A-CYP27B1-METTL1-FAM119B locus associated with multiple sclerosis

Background and aim

Several studies have highlighted the association of the 12q13.3–12q14.1 region with coeliac disease, type 1 diabetes, rheumatoid arthritis and multiple sclerosis (MS); however, the causal variants underlying diseases are still unclear. The authors sought to identify the functional variant of this region associated with MS.

Methods

Tag-single nucleotide polymorphism (SNP) analysis of the associated region encoding 15 genes was performed in 2876 MS patients and 2910 healthy Caucasian controls together with expression regulation analyses.

Results

rs6581155, which tagged 18 variants within a region where 9 genes map, was sufficient to model the association. This SNP was in total linkage disequilibrium (LD) with other polymorphisms that associated with the expression levels of FAM119B, AVIL, TSFM, TSPAN31 and CYP27B1 genes in different expression quantitative trait loci studies. Functional annotations from Encyclopedia of DNA Elements (ENCODE) showed that six out of these rs6581155-tagged-SNPs were located in regions with regulatory potential and only one of them, rs10877013, exhibited allele-dependent (ratio A/G=9.5-fold) and orientation-dependent (forward/reverse=2.7-fold) enhancer activity as determined by luciferase reporter assays. This enhancer is located in a region where a long-range chromatin interaction among the promoters and promoter-enhancer of several genes has been described, possibly affecting their expression simultaneously.

Conclusions

This study determines a functional variant which alters the enhancer activity of a regulatory element in the locus affecting the expression of several genes and explains the association of the 12q13.3–12q14.1 region with MS.

Brain dendritic cells: biology and pathology

Dendritic cells (DC) are the professional antigen-presenting cells of the immune system. In their quiescent and mature form, the presentation of self-antigens by DC leads to tolerance; whereas, antigen presentation by mature DC, after stimulation by pathogen-associated molecular patterns, leads to the onset of antigen-specific immunity. DC have been found in many of the major organs in mammals (e.g. skin, heart, lungs, intestines and spleen); while the brain has long been considered devoid of DC in the absence of neuroinflammation. Consequently, microglia, the resident immune cell of the brain, have been charged with many functional attributes commonly ascribed to DC. Recent evidence has challenged the notion that DC are either absent or minimal players in brain immune surveillance. This review will discuss the recent literature examining DC involvement within both the young and aged steady-state brain. We will also examine DC contributions during various forms of neuroinflammation resulting from neurodegenerative autoimmune disease, injury, and CNS infections. This review also touches upon DC trafficking between the central nervous system and peripheral immune compartments during viral infections, the new molecular technologies that could be employed to enhance our current understanding of brain DC ontogeny, and some potential therapeutic uses of DC within the CNS.

The conundrum of iron in multiple sclerosis--time for an individualised approach

Although the involvement of immune mechanisms in multiple sclerosis (MS) is undisputed, some argue that there is insufficient evidence to support the hypothesis that MS is an autoimmune disease, and that the difference between immune- and autoimmune disease mechanisms has yet to be clearly delineated. Uncertainties surrounding MS disease pathogenesis and the modest efficacy of currently used disease modifying treatments (DMTs) in the prevention of disability, warrant the need to explore other possibilities. It is evident from the literature that people diagnosed with MS differ widely in symptoms and clinical outcome--some patients have a benign disease course over many years without requiring any DMTs. Attempting to include all patients into a single entity is an oversimplification and may obscure important observations with therapeutic consequences. In this review we advocate an individualised approach named Pathology Supported Genetic Testing (PSGT), in which genetic tests are combined with biochemical measurements in order to identify subgroups of patients requiring different treatments. Iron dysregulation in MS is used as an example of how this approach may benefit patients. The theory that iron deposition in the brain contributes to MS pathogenesis has caused uncertainty among patients as to whether they should avoid iron. However, the fact that a subgroup of people diagnosed with MS show clinical improvement when they are on iron supplementation emphasises the importance of individualised therapy, based on genetic and biochemical determinations.

Pathogenic CD8 T cells in multiple sclerosis and its experimental models

A growing body of evidence suggests that autoreactive CD8 T cells contribute to the disease process in multiple sclerosis (MS). Lymphocytes in MS plaques are biased toward the CD8 lineage, and MS patients harbor CD8 T cells specific for multiple central nervous system (CNS) antigens. Currently, there are relatively few experimental model systems available to study these pathogenic CD8 T cells in vivo. However, the few studies that have been done characterizing the mechanisms used by CD8 T cells to induce CNS autoimmunity indicate that several of the paradigms of how CD4 T cells mediate CNS autoimmunity do not hold true for CD8 T cells or for patients with MS. Thus, myelin-specific CD4 T cells are likely to be one of several important mechanisms that drive CNS disease in MS patients. The focus of this review is to highlight the current models of pathogenic CNS-reactive CD8 T cells and the molecular mechanisms these lymphocytes use when causing CNS inflammation and damage. Understanding how CNS-reactive CD8 T cells escape tolerance induction and induce CNS autoimmunity is critical to our ability to propose and test new therapies for MS.

Autoimmune polyendocrine syndrome-3 in a patient with late-onset multiple sclerosis

We present here the rare case of a 73-year-old patient with very late-onset multiple sclerosis who developed autoimmune polyendocrine syndrome (APS)-3. Despite only a few reports describing the association between multiple sclerosis and APS, both of these diseases have been shown to be associated with HLA-DR4. Intriguingly, the HLA genotype profile of this patient included HLA-DR4 which, fine mapped to the DRB1*0405-DQA1*0303-DQB1*0401 extended haplotype, reported to be a susceptibility haplotype for APS-3 in Japan. This unique genetic background might explain the clinical picture of this patient.

Multiple sclerosis risk variant HLA-DRB1*1501 associates with high expression of DRB1 gene in different human populations

The human leukocyte antigen (HLA) DRB1*1501 has been consistently associated with multiple sclerosis (MS) in nearly all populations tested. This points to a specific antigen presentation as the pathogenic mechanism though this does not fully explain the disease association. The identification of expression quantitative trait loci (eQTL) for genes in the HLA locus poses the question of the role of gene expression in MS susceptibility. We analyzed the eQTLs in the HLA region with respect to MS-associated HLA-variants obtained from genome-wide association studies (GWAS). We found that the Tag of DRB1*1501, rs3135388 A allele, correlated with high expression of DRB1, DRB5 and DQB1 genes in a Caucasian population. In quantitative terms, the MS-risk AA genotype carriers of rs3135388 were associated with 15.7-, 5.2- and 8.3-fold higher expression of DQB1, DRB5 and DRB1, respectively, than the non-risk GG carriers. The haplotype analysis of expression-associated variants in a Spanish MS cohort revealed that high expression of DRB1 and DQB1 alone did not contribute to the disease. However, in Caucasian, Asian and African American populations, the DRB1*1501 allele was always highly expressed. In other immune related diseases such as type 1 diabetes, inflammatory bowel disease, ulcerative colitis, asthma and IgA deficiency, the best GWAS-associated HLA SNPs were also eQTLs for different HLA Class II genes. Our data suggest that the DR/DQ expression levels, together with specific structural properties of alleles, seem to be the causal effect in MS and in other immunopathologies rather than specific antigen presentation alone.

Polymorphisms in neuropsychiatric and neuroinflammatory disorders and the role of next generation sequencing in early diagnosis and treatment

A number of polymorphisms have been implicated in different neuropsychiatric and neurological disorders. Polymorphisms in neurological disorders with a central immune component are well described, mainly due to their role in increasing neurodegeneration. For example, the role of polymorphisms in Alzheimer's disease in accumulation of amyloid plaques is now well established. In contrast, polymorphisms resulting in or affecting psychiatric disorders are less well studied and frequently are not replicated by meta-analysis. Furthermore, even if a significant association has been confirmed, the role of the identified polymorphism in causing and/or augmenting the disorder is often difficult to rationalize. Here, we review polymorphisms found associated with different neuroinflammatory and neuropsychiatric disorders and discuss the role of next generation sequencing in early diagnosis and treatment and as a tool in studying their functional consequences.

[New gene map for multiple sclerosis]

BACKGROUND

Multiple sclerosis (MS) is a demyelinating, inflammatory disease of the central nervous system which affects young adults with a relapsing or progressive disease course. The etiology of the disease is unknown, but both environmental and genetic factors contribute to the risk of developing MS.

MATERIAL AND METHODS

We give an overview of new knowledge of the genetic risk factors for MS, based on our own work as well as on literature in this field.

RESULTS

Through genome-wide association studies and subsequent replication studies a series of novel MS genes have recently been identified, in addition to the HLA association previously described. The International MS Genetics Consortium in collaboration with the Wellcome Trust Case Control Consortium recently published a genome-wide study of 9,722 MS patients and 17,376 controls. Genome-wide significant association (p < 10-8) was observed for 29 new as well as 23 previously identified gene regions, in addition to the HLA-DRB1 and -A loci .The majority of these MS-associated regions encode immune-related molecules.

CONCLUSION

Genetic studies of large patient and control samples obtained through international and national collaborations have identified a list of more than 50 MS risk-gene regions, in addition to HLA-DRB1 and -A loci. The risk associated with each of these loci is low, however, they collectively point to the importance of immune-related pathways in the etiology of MS.

Epstein-Barr virus and multiple sclerosis: interaction with HLA

Epstein-Barr virus (EBV) infection, history of infectious mononucleosis (IM) and HLA-A and DRB1 have all been proposed as risk factors for multiple sclerosis (MS). Our aim was to analyse possible interactions between antibodies against Epstein-Barr virus nuclear antigen 1 (EBNA1) or EBNA1 fragments, presence of DRB1*15 and absence of A*02. The study population includes newly diagnosed cases and matched controls. Interaction on the additive scale was calculated using attributable proportion due to interaction (AP), which is the proportion of the incidence among individuals exposed to two interacting factors that is attributable to the interaction per se. IM showed association with MS, odds ratio (OR)=1.89 (1.45-2.48% confidence interval (CI)), as did raised EBNA1 IgG OR=1.74 (1.38-2.18 95%CI). All EBNA1 fragment IgGs were associated with MS risk. However, EBNA1 fragment 385-420 IgG levels were more strongly associated to MS than total EBNA1 IgG, OR=3.60 (2.75-4.72 95%CI), and also interacted with both DRB1*15 and absence of A*02, AP 0.60 (0.45-0.76 95%CI) and AP 0.39 (0.18-0.61 95%CI), respectively. The observed interaction between HLA class I and II genotype and reactivity to EBV-related epitopes suggest that the mechanism through which HLA genes influence the risk of MS may, at least in part, involve the immune control of EBV infection.

TRAIL/TRAIL receptor system and susceptibility to multiple sclerosis

The TNF-related apoptosis inducing ligand (TRAIL)/TRAIL receptor system participates in crucial steps in immune cell activation or differentiation. It is able to inhibit proliferation and activation of T cells and to induce apoptosis of neurons and oligodendrocytes, and seems to be implicated in autoimmune diseases. Thus, TRAIL and TRAIL receptor genes are potential candidates for involvement in susceptibility to multiple sclerosis (MS). To test whether single-nucleotide polymorphisms (SNPs) in the human genes encoding TRAIL, TRAILR-1, TRAILR-2, TRAILR-3 and TRAILR-4 are associated with MS susceptibility, we performed a candidate gene case-control study in the Spanish population. 59 SNPs in the TRAIL and TRAIL receptor genes were analysed in 628 MS patients and 660 controls, and validated in an additional cohort of 295 MS patients and 233 controls. Despite none of the SNPs withstood the highly conservative Bonferroni correction, three SNPs showing uncorrected p values<0.05 were successfully replicated: rs4894559 in TRAIL gene, p = 9.8×10⁻⁴, OR = 1.34; rs4872077, in TRAILR-1 gene, p = 0.005, OR = 1.72; and rs1001793 in TRAILR-2 gene, p = 0.012, OR = 0.84. The combination of the alleles G/T/A in these SNPs appears to be associated with a reduced risk of developing MS (p = 2.12×10⁻⁵, OR = 0.59). These results suggest that genes of the TRAIL/TRAIL receptor system exerts a genetic influence on MS.

The MHC, disease and selection

Given large sample sizes, whole genome screens are now able to identify even quite modest contributions of common human genetic variation to disease. These approaches, made possible by the development of high-throughput, dense SNP genotyping, find few associations stronger than those for the human MHC, in multigenic autoimmune conditions. They confirm earlier findings that the major variants affecting susceptibility and resistance to autoimmunity relate to MHC class I and class II genes. It is generally assumed, although there are few good examples, that selection for resistance to infection drives evolution of MHC variation. Many MHC-associated diseases may be the price paid for an effective immune response. Interestingly, the MHC appears to influence susceptibility to conditions unrelated to immunity, including some neuropathologies. The infectious history of the individual, conditioned by their MHC, may exert an indirect effect on these diseases, although there are hints of more direct involvement of MHC molecules in neuronal systems. Here I survey the variety of conditions associated with the MHC in relation to ideas that selection through disease resistance is dependent upon MHC variation, not only at the level of the individual, but also at the level of the population.

HLA-DRB1: genetic susceptibility and disability progression in a Spanish multiple sclerosis population

BACKGROUND AND OBJECTIVE

The association of HLA-DRB1*15 with susceptibility to multiple sclerosis (MS) has been consistently reported although its effect on the clinical phenotype is still controversial. The objectives of this study are to investigate the influence of the HLA-DRB1 alleles on the genetic susceptibility to MS and to study their impact on disability progression in a Spanish population.

METHODS

HLA-DRB1 typing was performed by PCR-SSP in 380 patients with sporadic MS and 1088 unrelated healthy controls. Allelic frequencies were compared between groups. We studied the correlation between the different alleles and the progression of MS.

RESULTS

The HLA-DRB1*15 allele in patients with MS had a statistically significant higher frequency when compared with controls (18.9% in patients vs. 10.1% in controls, Odds ratio (OR)=2.07, 95% CI=1.64-2.60, P<0.001). In the univariate analysis, the DRB1*01 and DRB1*04 alleles were associated with a worse prognosis when considering the time to reach an EDSS of 6, whereas the DRB1*03 was correlated with a better outcome. In the multivariate analysis, the alleles*01 and *04 were demonstrated to be independent factors to have a worse prognosis.

CONCLUSIONS

HLA-DRB1*15 is associated with MS when comparing patients with unrelated healthy controls in a Spanish population. The HLA-DRB1*01 and HLA-DRB1*04 alleles are related to a worse prognosis when considering the time taken to reach severe disability.

Role of gender in multiple sclerosis: clinical effects and potential molecular mechanisms

Multiple sclerosis (MS) is more prevalent in females than males, and this female predominance is increasing as time goes by. Additionally, gender appears to play critical roles in development, progression and treatment of MS, and is therefore an aspect that should always be considered in the design and interpretation of research and clinical trials for MS. In this review, factors that could potentially explain the gender-biased observations in MS are discussed. These include sex-specific differences between the male and female immune systems and nervous systems, genetic and epigenetic or environmental-related effects, the effects of gonadal hormones, and materno-fetal interactions.

Aggregation of multiple sclerosis genetic risk variants in multiple and single case families

OBJECTIVE

Multiple sclerosis (MS) is a multifactorial neurologic disease characterized by modest but tractable heritability. Genome-wide association studies have identified and/or validated multiple polymorphisms in approximately 16 genes associated with susceptibility. We aimed at investigating the aggregation of genetic MS risk markers in individuals by comparing multiple- and single-case families.

METHODS

A weighted log-additive integrative approach termed MS genetic burden (MSGB) was used to account for the well-established genetic variants from previous association studies and meta-analyses. The corresponding genetic burden and its transmission was analyzed in 1,213 independent MS families (810 sporadic and 403 multicase families).

RESULTS

MSGB analysis demonstrated a higher aggregation of susceptibility variants in multicase compared to sporadic MS families. In addition, the aggregation of non-major histocompatibility complex single nucleotide polymorphisms depended neither on gender nor on the presence or absence of HLA-DRB1*15:01 alleles. Interestingly, although a greater MSGB in siblings of MS patients was associated with an increased risk of MS (odds ratio, 2.1; p = 0.001), receiver operating characteristic curves of MSGB differences between probands and sibs (area under the receiver operator curves, 0.57 [95% confidence interval, 0.53-0.61]) show that case-control status prediction of MS cannot be achieved with the currently available genetic data.

INTERPRETATION

The primary interest in the MSGB concept resides in its capacity to integrate cumulative genetic contributions to MS risk. This analysis underlines the high variability of family load with known common variants. This novel approach can be extended to other genetically complex diseases. Despite the emphasis on assembling large case-control datasets, multigenerational, multiaffected families remain an invaluable resource for advancing the understanding of the genetic architecture of complex traits.

Recent insights into the mechanism of action of glatiramer acetate

Glatiramer acetate (GA, Copaxone®, co-polymer 1) is an immunomodulatory therapy approved in 1996 by the United States Food and Drug Administration for treatment of relapsing-remitting multiple sclerosis. GA has a good safety profile, moderate efficacy, and a unique mode of action. Recent evidence in an animal model of MS, experimental autoimmune encephalomyelitis (EAE), suggests that GA effects on NK cells and B cells may contribute to therapeutic efficacy. We review the mechanism of action of GA, with particular focus on recent data suggesting a role for regulatory B cells.

Biomarkers of inflammatory and auto-immune central nervous system disorders

PURPOSE OF REVIEW

Inflammatory and auto-immune disorders of the central nervous system are a heterogeneous group of disorders. Many of these disorders are potentially treatable with immune therapies that can reduce disability or prevent death. We review the clinical value of biomarkers which can aid in the diagnosis of paediatric inflammatory and auto-immune central nervous system (CNS) disorders.

RECENT FINDINGS

This review will first describe the clinical usefulness of nonspecific biomarkers of CNS inflammation such as cerebrospinal fluid neopterin and oligoclonal bands. Neopterin is produced by immune and neuronal cells after stimulation by interferon species and is increased in a broad range of inflammatory and auto-immune CNS disorders. Oligoclonal bands represent clonal production of immunoglobulin G in the CNS and are present in demyelinating, auto-immune, and infectious CNS disorders. In addition, we will review new advances in the immunogenetic investigation of familial auto-inflammatory disorders such as Aicardi-Goutières syndrome and Chronic Infantile Neurologic Cutaneous Articular syndrome. Finally, we will review the clinical utility of auto-antibodies in CNS disorders, with specific focus on auto-antibodies that bind to cell surface proteins such as N-methyl-D-asparate receptor, voltage-gated potassium channels, myelin oligodendrocyte glycoprotein, and aquaporin-4.

SUMMARY

These biomarkers are increasingly important in the recognition and treatment of inflammatory and auto-immune CNS disorders. Like many biomarkers in paediatric practice, it is essential to interpret the findings in the context of the patient history and examination.

MicroRNAs and Multiple Sclerosis

MicroRNAs (miRNAs) have recently emerged as a new class of modulators of gene expression. miRNAs control protein synthesis by targeting mRNAs for translational repression or degradation at the posttranscriptional level. These noncoding RNAs are endogenous, single-stranded molecules approximately 22 nucleotides in length and have roles in multiple facets of immunity, from regulation of development of key cellular players to activation and function in immune responses. Recent studies have shown that dysregulation of miRNAs involved in immune responses leads to autoimmunity. Multiple sclerosis (MS) serves as an example of a chronic and organ-specific autoimmune disease in which miRNAs modulate immune responses in the peripheral immune compartment and the neuroinflammatory process in the brain. For MS, miRNAs have the potential to serve as modifying drugs. In this review, we summarize current knowledge of miRNA biogenesis and mode of action and the diverse roles of miRNAs in modulating the immune and inflammatory responses. We also review the role of miRNAs in autoimmunity, focusing on emerging data regarding miRNA expression patterns in MS. Finally, we discuss the potential of miRNAs as a disease marker and a novel therapeutic target in MS. Better understanding of the role of miRNAs in MS will improve our knowledge of the pathogenesis of this disease.