The immunogenetics of multiple sclerosis

The Regulatory Role of Reticulons in Neurodegeneration: Insights Underpinning Therapeutic Potential for Neurodegenerative Diseases

In the last few decades, cytoplasmic organellar dysfunction, such as that of the endoplasmic reticulum (ER), has created a new area of research interest towards the development of serious health maladies including neurodegenerative diseases. In this context, the extensively dispersed family of ER-localized proteins, i.e. reticulons (RTNs), is gaining interest because of its regulative control over neural regeneration. As most neurodegenerative diseases are pathologically manifested with the accretion of misfolded proteins with subsequent induction of ER stress, the regulatory role of RTNs in neural dysfunction cannot be ignored. With the limited information available in the literature, delineation of the functional connection between rising consequences of neurodegenerative diseases and RTNs need to be elucidated. In this review, we provide a broad overview on the recently revealed regulatory roles of reticulons in the pathophysiology of several health maladies, with special emphasis on neurodegeneration. Additionally, we have also recapitulated the decisive role of RTN4 in neurite regeneration and highlighted how neurodegeneration and proteinopathies are mechanistically linked with each other through specific RTN paralogues. With the recent findings advocating zebrafish Rtn4b (a mammalian Nogo-A homologue) downregulation following central nervous system (CNS) lesion, RTNs provides new insight into the CNS regeneration. However, there are controversies with respect to the role of Rtn4b in zebrafish CNS regeneration. Given these controversies, the connection between the unique regenerative capabilities of zebrafish CNS by distinct compensatory mechanisms and Rtn4b signalling pathway could shed light on the development of new therapeutic strategies against serious neurodegenerative diseases.

Exome-Wide Search for Genes Associated With Central Nervous System Inflammatory Demyelinating Diseases Following CHIKV Infection: The Tip of the Iceberg

Chikungunya virus (CHIKV) is a re-emergent arbovirus that causes a disease characterized primarily by fever, rash and severe persistent polyarthralgia, although <1% of cases develop severe neurological manifestations such as inflammatory demyelinating diseases (IDD) of the central nervous system (CNS) like acute disseminated encephalomyelitis (ADEM) and extensive transverse myelitis. Genetic factors associated with host response and disease severity are still poorly understood. In this study, we performed whole-exome sequencing (WES) to identify HLA alleles, genes and cellular pathways associated with CNS IDD clinical phenotype outcomes following CHIKV infection. The cohort includes 345 patients of which 160 were confirmed for CHIKV. Six cases presented neurological manifestation mimetizing CNS IDD. WES data analysis was performed for 12 patients, including the CNS IDD cases and 6 CHIKV patients without any neurological manifestation. We identified 29 candidate genes harboring rare, pathogenic, or probably pathogenic variants in all exomes analyzed. HLA alleles were also determined and patients who developed CNS IDD shared a common signature with diseases such as Multiple sclerosis (MS) and Neuromyelitis Optica Spectrum Disorders (NMOSD). When these genes were included in Gene Ontology analyses, pathways associated with CNS IDD syndromes were retrieved, suggesting that CHIKV-induced CNS outcomesmay share a genetic background with other neurological disorders. To our knowledge, this study was the first genome-wide investigation of genetic risk factors for CNS phenotypes in CHIKV infection. Our data suggest that HLA-DRB1 alleles associated with demyelinating diseases may also confer risk of CNS IDD outcomes in patients with CHIKV infection.

Class II HLA (DRB1, & DQB1) alleles and IL7R (rs6897932) variants and the risk for Multiple Sclerosis in Kerala, India

BACKGROUND

Different human leukocyte antigen (HLA) variants are known to modulate the risk of multiple sclerosis. The main objective of this study was to identify HLA-DRB1 and HLA-DQB1 alleles and Non -HLA gene IL7R (rs6897932) variants associated with MS.

METHODS

Patients attending the MS clinic, diagnosed with Multiple Sclerosis as per Mc Donald diagnostic criteria were the subjects in the study. The association of the highly polymorphic HLA-DRB1 and HLA-DQB1 loci was determined by high resolution tissue typing and the genotyping of the IL7R (rs6897932) variants was performed by Sanger sequencing in MS patients (n = 81) and healthy individuals (n = 82).

RESULTS

HLA-DRB1*15:01/15:02 alleles (OR = 3.65; p< 0.0001) and HLA-DQB1*06:02 (OR=4.19, p<0.0001) were found to be positively associated while HLA-DRB1*14:04:01 (OR = 0.21; p = 0.0009) was found to be negatively associated with MS. The most significant predisposing HLA haplotype was found to be DRB1*15:01-DQB1*06:02 (OR=5.69, p<0.0001). Univariate analysis of IL7R SNP (rs6897932) showed no significant association with MS in our population whereas analysis of HLA-DRB1 alleles and IL7R (rs6897932) genotypes showed significant association between the HLA-DRB1*15:01/15:02 and the IL7R (rs6897932) CC genotype (OR = 3.58, p = 0.0002).

CONCLUSION

HLA-DRB1*15:01, 15:02 and DQB1*06:02 are the predisposing alleles while HLA-DRB1*14:04 is the protective allele for MS in our population.

Association between IL7 Receptor Alpha (Il7ra) gene rs6897932 polymorphism and the risk of Multiple Sclerosis: A meta-regression and meta-analysis

BACKGROUND

In this systematic review and meta-analysis, we aimed to find a consistent conclusion for the association between the interleukin 7 receptor alpha (IL7RA) gene rs6897932 single nucleotide polymorphism (SNP) and multiple sclerosis (MS) risk.

METHODS

Here, we performed a comprehensive systematic search in PubMed, Scopus, and Web of Science to find relevant studies published before November 2020 investigating the association between rs6897932 SNP and MS risk. In the pooled analysis, we determined the odds ratio (OR) and the corresponding 95% confidence interval (CI) for the association level between rs6897932 SNP and the risk of MS.

RESULTS

In the current meta-analysis 33 case-control studies (30 articles) containing 19351 patients and 21005 healthy controls certify the inclusion criteria. According to the pooled analysis, a statistically significant association of IL7RA gene rs6897932 SNP with MS risk was found across recessive model (OR= 0.84, 95% CI= 0.77-0.92, P< 0.001, FEM), allelic model (OR= 0.91, 95% CI= 0.85-0.99, P= 0. 02, REM), TT vs. CC model (OR= 0.79, 95% CI= 0.67-0.93, P= 0.005, REM). Moreover, the subgroup analysis based on the ethnicity indicated a negative significant association in Europeans; dominant model (OR= 0.88, 95% CI= 0.78-1.01, P= 0.06, REM), recessive model (OR= 0.79, 95% CI= 0.71-0.88, P< 0.001, REM), allelic model (OR= 0.88, 95% CI= 0.81-0.96, P= 0.003, REM), TT vs. CC model (OR= 0.74, 95% CI= 0.61-0.88, P<0.001, REM) models. Nonetheless, no significant association was detected in Asians and Americans.

CONCLUSIONS

IL7RA gene rs6897932 SNP decreases MS susceptibility in overall population and Europeans.

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.

IL7RA genetic variants differentially affect IL-7Rα expression and alternative splicing: a role in autoimmune and infectious diseases?

Interleukin-7 receptor α chain (IL-7Rα) single nucleotide polymorphisms (SNPs) are associated with susceptibility to immunopathologies like autoimmune and inflammatory diseases. The current hypothesis about underlying mechanisms is based on the regulation of IL-7 availability for self-reactive T cells by influencing the generation of a soluble (s)IL-7Rα variant. This assumption was mainly predicated on the well-defined IL7RA SNP rs6897932, which affects alternative splicing and causes aberrant generation of the sIL-7Rα variant with potential effects on the IL-7 serum reservoir. However, more recent studies shed light on novel functions of autoimmunity risk-associated IL7RA SNPs and characterized the largely neglected effect of rs6897932 on membrane (m)IL-7Rα expression. These findings as well as a described role of impaired mIL-7Rα expression and IL7RA SNP influence on chronic infectious diseases necessitates the reevaluation of previous findings on the role of IL7RA SNPs in immunopathology.

Therapeutic potential of enhancer of zeste homolog 2 in autoimmune diseases

Introduction: Autoimmune diseases (ADs) are idiopathic and heterogeneous disorders with contentious pathophysiology. Great strides have been made in epigenetics and its involvement in ADs. Zeste homolog 2 (EZH2) has sparked extensive interest because of its pleiotropic roles in distinct pathologic contexts.Areas covered: This review summarizes the epigenetic functions and the biological significance of EZH2 in the etiology of rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), type 1 diabetes (T1D), inflammatory bowel disease (IBD), multiple sclerosis (MS), and systemic sclerosis (SSc). A brief recapitulation of the therapeutic potential of EZH2 targeting is provided.Expert opinion: There are questions marks and controversies surrounding the feasibility and safety of EZH2 targeting; it is recommended in RA and SLE, but queried in T1D, IBD, MS, and SSc. Future work should focus on contrast studies, systematic analyses and preclinical studies with optimizing methodologies. Selective research studies conducted in a stage-dependent manner are necessary because of the relapsing-remitting clinical paradigms.

CD4+ T-Cells With High Common γ Chain Expression and Disturbed Cytokine Production Are Enriched in Children With Type-1 Diabetes

The common gamma chain (γ_c) contributes to the formation of different cytokine receptors [e.g., IL-2 receptor (IL-2R), IL-7R, and IL-15R], which are important for generation of self-reactive T-cells in autoimmune diseases, like in type 1 diabetes (T1D). Whereas, the roles of membrane and soluble IL-2Rα and IL-7Rα variants in T1D disease pathogenesis are well-described, effects of γ_c expression and availability for dependent receptors remain elusive. We investigated expression of the γ_c and dependent receptors on T-cells and soluble γ_c concentrations in serum from patients with T1D (n = 34) and healthy controls (n = 27). Effector T-cell cytokines as well as IL-2, IL-7, and IL-15 induced STAT5 phosphorylation were analyzed to determine functional implications of differential γ_c expression of CD4⁺ T-cell subsets classified by t-distributed Stochastic Neighbor Embedding (t-SNE) analyses. We found increased γ_c and IL-7Rα expression of CD4⁺ T-cells from T1D patients as compared to controls. t-SNE analyses assigned differential expression to subsets of memory T-cells co-expressing γ_c and IL-7Rα. Whereas, γ_c expression was positively correlated with IL-2Rα in memory T-cells from healthy controls, no dependency was found for patients with T1D. Similarly, the effector T-cell cytokine, IL-21, correlated inversely with γ_c expression in healthy controls, but not in T1D patients. Finally, T1D patients with high γ_c expression had increased proportions of IL-2 sensitive pSTAT5⁺ effector T-cells. These results indicated aberrantly high γ_c expression of T-cells from T1D patients with implications on dependent cytokine receptor signaling and effector T-cell cytokine production.

Evaluation of the major histocompatibility complex (MHC) class II as a candidate for sudden acquired retinal degeneration syndrome (SARDS) in Dachshunds

Objective

Sudden acquired retinal degeneration syndrome (SARDS) is one of the leading causes of acute blindness in dogs, with an unknown etiology and no effective treatment. Certain breeds such as Dachshunds are overrepresented among SARDS patients, and therefore, the syndrome is suspected to have a genetic component. The objective of this study was to determine if a genetic locus associated with SARDS in Dachshunds could be identified using a genome‐wide association study (GWAS).

Procedures

Genome‐wide association mapping was performed in 15 SARDS‐affected and 16 unaffected Dachshunds. Genotyping of three classical DLA class II genes (DLA‐DRB1, DLA‐DQA1, and DLA‐DQB1) was performed in 34 SARDS‐affected and 66 unaffected Dachshunds to evaluate for an association in this region.

Results

Although no single nucleotide polymorphisms (SNPs) were of genome‐wide statistical significance (P_Bonferroni < 0.05), 5 of the top 9 SNPs were in the major histocompatibility complex (MHC). Using DLA typing, the allele DLA‐DRB1*09401 was identified as a risk factor for the development of SARDS (P = 0.0032, OR = 4.0). The alleles DLA‐DQB1*00101 (P = 0.0050, OR = 0.31), DLA‐DQA1*00901 (P = 0.0087, OR = 0.33), and a previously identified DLA‐DRB1allele described as “DRB1‐T” (P = 0.0284, OR = 0.37) were identified as protective factors.

Conclusions

Although far from definitive, association of SARDS with alleles of immunologic importance further supports the hypothesis that autoimmunity may play a role in the pathogenesis of SARDS.

CHARACTER OF DISTRIBUTION OF HLA II ANTIGENS IN PATIENTS WITH AVERAGE AND SEVERE FORMS OF ACNE

This article presents information about the distribution of antigens of the second class in patients with papulo-pustular and nodulous forms of acne. Class II antigens distribution was estimated as the total Group and groups of patients allocated depending on the severity of the clinical picture. Association revealed the presence of severe acne with antigens of histocompatibility of HLA-complex that confirms the importance of immunogenetic factors in the pathogenesis of this condition.

ATX-MS-1467 Induces Long-Term Tolerance to Myelin Basic Protein in (DR2 × Ob1)F1 Mice by Induction of IL-10-Secreting iTregs

INTRODUCTION

Antigen-specific immunotherapy could provide a targeted approach for the treatment of multiple sclerosis that removes the need for broad-acting immunomodulatory drugs. ATX-MS-1467 is a mixture of four peptides identified as the main immune-dominant disease-associated T-cell epitopes in myelin basic protein (MBP), an autoimmune target for activated autoreactive T cells in multiple sclerosis. Previous animal studies have shown that ATX-MS-1467 treatment prevented the worsening of signs of disease in experimental autoimmune encephalitis (EAE) in the humanized (DR2 × Ob1)F1 mouse in a dose-dependent fashion.

METHODS AND RESULTS

Our study extends these observations to show that subcutaneous treatment with 100 µg of ATX-MS-1467 after induction of EAE in the same mouse model reversed established clinical disability (p < 0.0001) and histological markers of inflammation and demyelination (p < 0.001) compared with vehicle-treated animals; furthermore, in longitudinal magnetic resonance imaging analyses, disruption of blood-brain barrier integrity was reversed, compared with vehicle-treated animals (p < 0.05). Chronic treatment with ATX-MS-1467 was associated with an enduring shift from a pro-inflammatory to a tolerogenic state in the periphery, as shown by an increase in interleukin 10 secretion, relative to interleukin 2, interleukin 17 and interferon γ, a decrease in splenocyte proliferation and an increase in interleukin 10+ Foxp3- T cells in the spleen.

CONCLUSION

Our results suggest that ATX-MS-1467 can induce splenic iTregs and long-term tolerance to MBP with the potential to partially reverse the pathology of multiple sclerosis, particularly during the early stages of the disease.

FUNDING

EMD Serono, Inc., a business of Merck KGaA.

HLA-DRB1*15 association with multiple sclerosis is confirmed in a multigenerational Italian family

Environmental and genetic factors seem to play a pathogenetic role in multiple sclerosis (MS). The genetic component is partly suggested by familial aggregation of cases; however, MS families with affected subjects over different generations have rarely been described. The aim of this study was to report clinical and genetic features of a multigenerational MS family and to perform a review of the literature on this topic. We describe a multigenerational Italian family with six individuals affected by MS, showing different clinical and neuroradiological findings. HLA-DRB1* typing revealed the presence of the DRB1*15:01 allele in all the MS cases and in 4/5 non-affected subjects. Reports on six multigenerational MS families have previously been published, giving similar results. The HLA-DRB1*15:01 allele was confirmed to be linked to MS disease in this family; moreover, its presence in non-affected subjects suggests the involvement of other susceptibility factors in the development and expression of the disease, in accordance with the complex disease model now attributed to MS.

Network-based analysis of differentially expressed genes in cerebrospinal fluid (CSF) and blood reveals new candidate genes for multiple sclerosis

BACKGROUND

The involvement of multiple genes and missing heritability, which are dominant in complex diseases such as multiple sclerosis (MS), entail using network biology to better elucidate their molecular basis and genetic factors. We therefore aimed to integrate interactome (protein-protein interaction (PPI)) and transcriptomes data to construct and analyze PPI networks for MS disease.

METHODS

Gene expression profiles in paired cerebrospinal fluid (CSF) and peripheral blood mononuclear cells (PBMCs) samples from MS patients, sampled in relapse or remission and controls, were analyzed. Differentially expressed genes which determined only in CSF (MS vs. control) and PBMCs (relapse vs. remission) separately integrated with PPI data to construct the Query-Query PPI (QQPPI) networks. The networks were further analyzed to investigate more central genes, functional modules and complexes involved in MS progression.

RESULTS

The networks were analyzed and high centrality genes were identified. Exploration of functional modules and complexes showed that the majority of high centrality genes incorporated in biological pathways driving MS pathogenesis. Proteasome and spliceosome were also noticeable in enriched pathways in PBMCs (relapse vs. remission) which were identified by both modularity and clique analyses. Finally, STK4, RB1, CDKN1A, CDK1, RAC1, EZH2, SDCBP genes in CSF (MS vs. control) and CDC37, MAP3K3, MYC genes in PBMCs (relapse vs. remission) were identified as potential candidate genes for MS, which were the more central genes involved in biological pathways.

DISCUSSION

This study showed that network-based analysis could explicate the complex interplay between biological processes underlying MS. Furthermore, an experimental validation of candidate genes can lead to identification of potential therapeutic targets.

Are human endogenous retroviruses triggers of autoimmune diseases? Unveiling associations of three diseases and viral loci

Autoimmune diseases encompass a plethora of conditions in which the immune system attacks its own tissue, identifying them as foreign. Multiple factors are thought to contribute to the development of immune response to self, including differences in genotypes, hormonal milieu, and environmental factors. Viruses including human endogenous retroviruses have long been linked to the occurrence of autoimmunity, but never proven to be causative factors. Endogenous viruses are retroviral sequences embedded in the host germline DNA and transmitted vertically through successive generations in a Mendelian manner. In this study by means of genetic epidemiology, we have searched for the involvement of endogenous retroviruses in three selected autoimmune diseases: multiple sclerosis, type 1 diabetes mellitus, and rheumatoid arthritis. We found that at least one human endogenous retroviral locus was associated with each of the three diseases. Although there was a significant overlap, most loci only occurred in one of the studied disease. Remarkably, within each disease, there was a statistical interaction (synergy) between two loci. Additional synergy between retroviral loci and human lymphocyte antigens is reported for multiple sclerosis. We speculate the possibility that recombinants or mixed viral particles are formed and that the resulting viruses stimulate the innate immune system, thereby initiating the autoimmune response.

Epidemiology of Multiple Sclerosis

The epidemiology of multiple sclerosis (MS) includes a consideration of genetic and environmental factors. Comparative studies of different populations have revealed prevalence and incidence rates that vary with geography and ethnicity. With a prevalence ranging from 2 per 100,000 in Japan to greater than 100 per 100,000 in Northern Europe and North America, the burden of MS is similarly unevenly influenced by longevity and comorbid disorders. Well-powered genome-wide association studies have investigated the genetic substrate of MS, providing insight into autoimmune mechanisms involved in the etiopathogenesis of MS and elucidating possible avenues of biological treatment.

Basement membranes and autoimmune diseases

Basement membrane components are targets of autoimmune attack in diverse diseases that destroy kidneys, lungs, skin, mucous membranes, joints, and other organs in man. Epitopes on collagen and laminin, in particular, are targeted by autoantibodies and T cells in anti-glomerular basement membrane glomerulonephritis, Goodpasture's disease, rheumatoid arthritis, post-lung transplant bronchiolitis obliterans syndrome, and multiple autoimmune dermatoses. This review examines major diseases linked to basement membrane autoreactivity, with a focus on investigations in patients and animal models that advance our understanding of disease pathogenesis. Autoimmunity to glomerular basement membrane type IV is discussed in depth as a prototypic organ-specific autoimmune disease yielding novel insights into the complexity of anti-basement membrane immunity and the roles of genetic and environmental susceptibility.

The association of IL-18 gene promoter polymorphisms and the levels of serum IL-18 on the risk of multiple sclerosis

OBJECTIVES

Multiple sclerosis is an inflammatory condition of the central nervous system whose etiology is influenced by immunologic, genetic, and environmental factors. Aim of the present study was to determine if any relation exists between IL-18 -137C/G and -607C/A gene promoter polymorphisms on the individual susceptibility of multiple sclerosis and also to investigate the possible effect of IL-18 activity regarding this kind of polymorphism and MS.

PATIENTS AND METHODS

113 patients with clinically definite MS and 135 ethnically-matched controls were participated in this study. IL-18 -137C/G and -607C/A gene promoter polymorphisms were analyzed by Sequence Specific Polymerase Chain Reaction (SS-PCR), while levels of serum IL-18 were measured by Enzyme Linked Immunoassay Assay (ELISA) in patients with MS and healthy controls.

RESULTS

Our results showed that the IL-18 -607AA genotype indicated 6 times higher risk in the development of MS (OR=6.883; 3.17-14.96; p<0.001). According to our findings, smoking seems to be an important confounding factor in MS patients with carrying IL-18 -607 AA and CA+AA genotypes. However, no meaningful association was found with IL-18 -137C/G gene promoter polymorphism.

CONCLUSION

In conclusion, we suggest that IL-18 -607C/A gene promoter polymorphism is a major genetic factor for determining individual susceptibility to MS, where smoking status also increases the risk of MS.

The Possible Future Roles for iPSC-Derived Therapy for Autoimmune Diseases

The ability to generate inducible pluripotent stem cells (iPSCs) and the potential for their use in treatment of human disease is of immense interest. Autoimmune diseases, with their limited treatment choices are a potential target for the clinical application of stem cell and iPSC technology. IPSCs provide three potential ways of treating autoimmune disease; (i) providing pure replacement of lost cells (immuno-reconstitution); (ii) through immune-modulation of the disease process in vivo; and (iii) for the purposes of disease modeling in vitro. In this review, we will use examples of systemic, system-specific and organ-specific autoimmunity to explore the potential applications of iPSCs for treatment of autoimmune diseases and review the evidence of iPSC technology in auto-immunity to date.

Multiple sclerosis and the role of immune cells

Multiple sclerosis (MS) is a complex disease with many different immune cells involved in its pathogenesis, and in particular T cells as the most recognized cell type. Recently, the innate immune system has also been researched for its effect on the disease. Hence, cells of the immune system play vital roles in either ameliorating or exacerbating the disease. The genetic and environmental factors, as well as the etiology and pathogenesis are of utmost importance for the development of MS. An insight into the roles play by T cells, B cells, natural killer cells, and dendritic cells in MS and the animal model experimental autoimmune encephalomyelitis, will be presented. Understanding the mechanisms of action for current therapeutic modalities should help developing new therapeutic tools to treat this disease and other autoimmune diseases.

Multiple sclerosis and psychiatric disorders: Comorbidity and sibling risk in a nationwide Swedish cohort

Background:

Psychiatric disorders are known to be prevalent in multiple sclerosis (MS).

Objective:

The objective of this paper is to study comorbidity between MS and bipolar disorder, schizophrenia and depression in a nationwide cohort and to determine whether shared genetic liability underlies the putative association.

Methods:

We identified ICD-diagnosed patients with MS ( n = 16,467), bipolar disorder ( n = 30,761), schizophrenia ( n = 22,781) and depression ( n = 172,479) in the Swedish National Patient Register and identified their siblings in the Multi-Generation Register. The risk of MS was compared in psychiatric patients and in matched unexposed individuals. Shared familial risk between MS and psychiatric disorders was estimated by sibling comparison.

Results:

The risk of MS was increased in patients with bipolar disorder (hazard ratio (HR) 1.8, 95% confidence interval (CI) 1.6–2.2, p < 0.0001) and depression (HR 1.9, 95% CI 1.7–2.0, p < 0.0001). MS risk in schizophrenia was decreased (HR 0.6, 95% CI 0.4–0.9, p = 0.005). The association between having a sibling with a psychiatric disorder and developing MS was not significant.

Conclusion:

We found a strong positive association between MS and bipolar disorder and depression that could not be explained by genetic liability. The unexpected negative association between MS and schizophrenia might be spurious or indicate possible protective mechanisms that warrant further exploration.

TIRC7 and HLA-DR axis contributes to inflammation in multiple sclerosis

BACKGROUND AND OBJECTIVE

Interactions between TIRC7 (a novel seven-transmembrane receptor on activated lymphocytes) and its ligand HLA-DR might be involved in the inflammatory process in multiple sclerosis (MS).

METHODS

Methods comprised immunohistochemistry and microscopy on archival MS autopsies, proliferation-, cytokine-, and surface-staining assays using peripheral blood lymphocytes (PBLs) from MS patients and an in vitro model.

RESULTS

TIRC7 was expressed in brain-infiltrating lymphocytes and strongly correlated with disease activity in MS. TIRC7 expression was reduced in T cells and induced in B cells in PBLs obtained from MS patients. After ex vivo activation, T cell expression of TIRC7 was restored in patients with active MS disease. The interaction of TIRC7(+) T lymphocytes with cells expressing HLA-DR on their surface led to T cell proliferation and activation whereas an anti-TIRC7 mAb preventing interactions with its ligand inhibited proliferation and Th1 and Th17 cytokine expression in T cells obtained from MS patients and in myelin basic protein-specific T cell clone.

CONCLUSION

Our findings suggest that TIRC7 is involved in inflammation in MS and anti-TIRC7 mAb can prevent immune activation via selective inhibition of Th1- and Th17-associated cytokine expression. This targeting approach may become a novel treatment option for MS.

Endogenous retroviruses and multiple sclerosis-new pieces to the puzzle

The possibility that retroviruses play a role in multiple sclerosis (MS) has long been considered; accumulating findings suggest this to be most likely in the form of human endogenous retroviruses (HERVs). A genetic test series of fifty endogenous retroviral loci for association with MS in Danes showed SNP markers near a specific endogenous retroviral locus, HERV-Fc1 located on the X-chromosome, to be positive. Bout Onset MS was associated with the HERV-Fc1 locus, while a rarer form, Primary Progressive MS, was not. Moreover, HERV-Fc1 Gag RNA in plasma was increased 4-fold in patients with recent history of attacks, relative to patients in a stable state and to healthy controls.

Finally, genetic variations in restriction genes for retroviruses influence the risk of MS, providing further support for a role of retroviral elements in disease.

We speculate that endogenous retroviruses may activate the innate immune system in a variety of ways, involving the host proteins, TRIMs, TLRs, TREXs and STING. Observations in HIV-positive patients suggest that antiretroviral drugs can curb MS. Thus, these new findings regarding the etiology and pathogenesis of MS, suggest alternative ways to challenge autoimmune diseases.

A new look at chronicChlamydiainfections and the role of the MHC/HLA in diseases of the CNS

Chlamydia has attracted increased attention as a possible cause of atheromatous plaques, cerebrovascular diseases, multiple sclerosis, Alzheimer’s disease and schizophrenia. The Chlamydia species are obligate intracellular parasites. The unique biphasic life cycle of Chlamydia permits the parasite to persist in cells for years. Acute Chlamydia infections can be recognized serologically in the peripheral blood through observation of rising antibody titers or molecularly using various PCR methods. However, the identification of chronic Chlamydia infection is hampered by many hurdles. This has initiated controversial discussions about the true involvement of Chlamydia, particularly in the CNS. The aspects of the discussion will be inspected as well as the vulnerability of the neuronal MHC to immune reactions.

CD226 Gly307Ser association with neuromyelitis optica in Southern Han Chinese

BACKGROUND

Neuromyelitis optica (NMO) and multiple sclerosis (MS) are autoimmune diseases of the central nervous system with complex pathogeneses. NMO was once considered to be a severe variant of MS. There has been more evidence that a non-synonymous exchange (rs763361/Gly307Ser) in the gene for CD226 is linked to several autoimmune diseases including multiple sclerosis (MS). However, no studies have investigated the role of rs763361 in the pathogenesis of NMO.

OBJECTIVES

The goal of our study is to evaluate the role of CD226 Gly307Ser in neuromyelitis optica (NMO) in Southern Han Chinese.

METHODS

Eight-nine NMO patients, 93 relapsing-remitting multiple sclerosis (RRMS) patients, and 122 controls (CTLs) were enrolled. The rs763361 alleles of the subjects were determined by sequencing-based typing.

RESULTS

The results strongly support that the TT genotypes are associated with NMO but are not significantly correlated with susceptibility for MS.

CONCLUSIONS

CD226 Gly307Ser may correlate with risk of NMO in Southern Han Chinese.

A model for personalized in vivo analysis of human immune responsiveness

Studies of human immune diseases are generally limited to the analysis of peripheral blood lymphocytes of heterogeneous patient populations. Improved models are needed to allow analysis of fundamental immunologic abnormalities predisposing to disease and in which to assess immunotherapies. Immunodeficient mice receiving human fetal thymus grafts and fetal CD34(+) cells intravenously produce robust human immune systems, allowing analysis of human T cell development and function. However, to use humanized mice to study human immune-mediated disorders, immune systems must be generated from adult hematopoietic cells. Here, we demonstrated robust immune reconstitution in mice with hematopoietic stem cells (HSCs) aspirated from bone marrow of adults with type 1 diabetes (T1D) and healthy control volunteers. In these humanized mice, cryopreservation of human leukocyte antigen allele-matched fetal thymic tissue prevented allogeneic adult HSC rejection. Newly generated T cells, which included regulatory T cells (T(regs)), were functional and self-tolerant and had a diverse repertoire. The immune recognition of these mice mimicked that of the adult CD34(+) cell donor, but the T cell phenotypes were more predominantly "naïve" than those of the adult donors. HSCs from T1D and control donors generated similar numbers of natural T(regs) intrathymically; however, peripheral T cells from T1D subjects showed increased proportions of activated or memory cells compared to controls, suggesting possible HSC-intrinsic differences in T cell homeostasis that might underlie immune pathology in T1D. This "personalized immune" mouse provides a new model for individualized analysis of human immune responses that may provide new insights into not only T1D but also other forms of immune function and dysfunction as well.

Identification of protein networks involved in the disease course of experimental autoimmune encephalomyelitis, an animal model of multiple sclerosis

A more detailed insight into disease mechanisms of multiple sclerosis (MS) is crucial for the development of new and more effective therapies. MS is a chronic inflammatory autoimmune disease of the central nervous system. The aim of this study is to identify novel disease associated proteins involved in the development of inflammatory brain lesions, to help unravel underlying disease processes. Brainstem proteins were obtained from rats with MBP induced acute experimental autoimmune encephalomyelitis (EAE), a well characterized disease model of MS. Samples were collected at different time points: just before onset of symptoms, at the top of the disease and following recovery. To analyze changes in the brainstem proteome during the disease course, a quantitative proteomics study was performed using two-dimensional difference in-gel electrophoresis (2D-DIGE) followed by mass spectrometry. We identified 75 unique proteins in 92 spots with a significant abundance difference between the experimental groups. To find disease-related networks, these regulated proteins were mapped to existing biological networks by Ingenuity Pathway Analysis (IPA). The analysis revealed that 70% of these proteins have been described to take part in neurological disease. Furthermore, some focus networks were created by IPA. These networks suggest an integrated regulation of the identified proteins with the addition of some putative regulators. Post-synaptic density protein 95 (DLG4), a key player in neuronal signalling and calcium-activated potassium channel alpha 1 (KCNMA1), involved in neurotransmitter release, are 2 putative regulators connecting 64% of the identified proteins. Functional blocking of the KCNMA1 in macrophages was able to alter myelin phagocytosis, a disease mechanism highly involved in EAE and MS pathology. Quantitative analysis of differentially expressed brainstem proteins in an animal model of MS is a first step to identify disease-associated proteins and networks that warrant further research to study their actual contribution to disease pathology.

Multiple sclerosis is not a disease of the immune system

Multiple sclerosis is a complex neurodegenerative disease, thought to arise through autoimmunity against antigens of the central nervous system. The autoimmunity hypothesis fails to explain why genetic and environmental risk factors linked to the disease in one population tend to be unimportant in other populations. Despite great advances in documenting the cell and molecular mechanisms underlying MS pathophysiology, the autoimmunity framework has also been unable to develop a comprehensive explanation of the etiology of the disease. I propose a new framework for understanding MS as a dysfunction of the metabolism of lipids. Specifically, the homeostasis of lipid metabolism collapses during acute-phase inflammatory response triggered by a pathogen, trauma, or stress, starting a feedback loop of increased oxidative stress, inflammatory response, and proliferation of cytoxic foam cells that cross the blood brain barrier and both catabolize myelin and prevent remyelination. Understanding MS as a chronic metabolic disorder illuminates four aspects of disease onset and progression: 1) its pathophysiology; 2) genetic susceptibility; 3) environmental and pathogen triggers; and 4) the skewed sex ratio of patients. It also suggests new avenues for treatment.

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.

Expanded dog leukocyte antigen (DLA) single nucleotide polymorphism (SNP) genotyping reveals spurious class II associations

The dog leukocyte antigen (DLA) system contains many of the functional genes of the immune system, thereby making it a candidate region for involvement in immune-mediated disorders. A number of studies have identified associations between specific DLA class II haplotypes and canine immune hemolytic anemia, thyroiditis, immune polyarthritis, type I diabetes mellitus, hypoadrenocorticism, systemic lupus erythematosus-related disease complex, necrotizing meningoencephalitis (NME) and anal furunculosis. These studies have relied on sequencing approximately 300 bases of exon 2 of each of the DLA class II genes: DLA-DRB1, DLA-DQA1 and DLA-DQB1. In the present study, an association (odds ratio=4.29) was identified by this method between Weimaraner dogs with hypertrophic osteodystrophy (HOD) and DLA-DRB1∗01501. To fine map the association with HOD, a genotyping assay of 126 coding single nucleotide polymorphisms (SNPs) from across the entire DLA, spanning a region of 2.5 Mb (3,320,000-5,830,000) on CFA12, was developed and tested on Weimaraners with HOD, as well as two additional breeds with diseases associated with DLA class II: Nova Scotia duck tolling retrievers with hypoadrenocorticism and Pug dogs with NME. No significant associations were found between Weimaraners with HOD or Nova Scotia duck tolling retrievers with hypoadrenocorticism and SNPs spanning the DLA region. In contrast, significant associations were found with NME in Pug dogs, although the associated region extended beyond the class II genes. By including a larger number of genes from a larger genomic region, a SNP genotyping assay was generated that provides coverage of the extended DLA region and may be useful in identifying and fine mapping DLA associations in dogs.

Genomic medicine and neurological disease

"Genomic medicine" refers to the diagnosis, optimized management, and treatment of disease--as well as screening, counseling, and disease gene identification--in the context of information provided by an individual patient's personal genome. Genomic medicine, to some extent synonymous with "personalized medicine," has been made possible by recent advances in genome technologies. Genomic medicine represents a new approach to health care and disease management that attempts to optimize the care of a patient based upon information gleaned from his or her personal genome sequence. In this review, we describe recent progress in genomic medicine as it relates to neurological disease. Many neurological disorders either segregate as Mendelian phenotypes or occur sporadically in association with a new mutation in a single gene. Heritability also contributes to other neurological conditions that appear to exhibit more complex genetics. In addition to discussing current knowledge in this field, we offer suggestions for maximizing the utility of genomic information in clinical practice as the field of genomic medicine unfolds.

Prognostic significance of interleukin-7 receptor-α gene polymorphisms in allogeneic stem-cell transplantation: a confirmatory study

BACKGROUND

Interleukin-7 (IL-7) is a hematopoietic cytokine essential for T-cell development in the thymus and for the maintenance of peripheral T cells. A previous study of single nucleotide polymorphisms in the exons of IL-7 receptor α-chain (IL-7Rα) in a Danish cohort of patients undergoing allogeneic stem-cell transplantation (SCT) identified donor genotype GG at rs1494555 as a risk factor for treatment-related mortality (TRM) after SCT.

METHODS

In this validation study, 116 British and French SCT patients and their donors were investigated by sequence-specific primer polymerase chain reaction.

RESULTS

Both donor rs1494555GG genotype and the tightly coupled rs1494558TT genotype were significantly associated with grade 3 to 4 acute graft versus host disease. Although both genotypes tended to be associated with increased TRM, this did not translate into altered overall survival.

CONCLUSION

The present data indicate that the IL-7 pathway is associated with alloreactivity in SCT, which is in line with the previously observed association between IL-7Rα single nucleotide polymorphisms and TRM.

Comprehensive genotyping in two homogeneous Graves' disease samples reveals major and novel HLA association alleles

BACKGROUND

Graves' disease (GD) is the leading cause of hyperthyroidism and thyroid eye disease inherited as a complex trait. Although geoepidemiology studies showed relatively higher prevalence of GD in Asians than in Caucasians, previous genetic studies were contradictory concerning whether and/or which human leukocyte antigen (HLA) alleles are associated with GD in Asians.

METHODOLOGY/PRINCIPAL FINDINGS

We conducted a case-control association study (499 unrelated GD cases and 504 controls) and a replication in an independent family sample (419 GD individuals and their 282 relatives in 165 families). To minimize genetic and phenotypic heterogeneity, we included only ethnic Chinese Han population in Taiwan and excluded subjects with hypothyroidism. We performed direct and comprehensive genotyping of six classical HLA loci (HLA-A, -B, -C, -DPB1, -DQB1 and -DRB1) to 4-digit resolution. Combining the data of two sample populations, we found that B*46:01 (odds ratio under dominant model [OR]  = 1.33, Bonferroni corrected combined P [P(Bc)]  = 1.17 x 10⁻²), DPB1*05:01 (OR  = 2.34, P(Bc) = 2.58 x 10⁻¹⁰), DQB1*03:02 (OR  = 0.62, P(Bc)  = 1.97 x 10⁻²), DRB1*15:01 (OR  = 1.68, P(Bc) = 1.22 x 10⁻²) and DRB1*16:02 (OR  = 2.63, P(Bc)  = 1.46 x 10⁻⁵) were associated with GD. HLA-DPB1*05:01 is the major gene of GD in our population and singly accounts for 48.4% of population-attributable risk.

CONCLUSIONS/SIGNIFICANCE

These GD-associated alleles we identified in ethnic Chinese Hans, and those identified in other Asian studies, are totally distinct from the known associated alleles in Caucasians. Identification of population-specific association alleles is the critical first step for individualized medicine. Furthermore, comparison between different susceptibility/protective alleles across populations could facilitate generation of novel hypothesis about GD pathophysiology and indicate a new direction for future investigation.

Association between the IL7R T244I polymorphism and multiple sclerosis: a meta-analysis

Previously published analyses of the association between the interleukin 7 receptor (IL7R) T244I polymorphism (rs6897932) and multiple sclerosis (MS) have yielded conflicting results. We performed a meta-analysis to assess whether the combined data showed this association, and to investigate its effect size. We analyzed 10 studies identified from PubMed (12,185 MS patients and 15,855 controls) and calculated the odds ratios (ORs) and 95% confidence intervals (CIs) for the C-allele, the C/C genotype (recessive effect) and the C/C + C/T (dominant effect) genotype. Heterogeneity within and between studies was observed: allele C: Q = 30.86, P = 0.002; genotype C/C: Q = 30.28, P = 0.003. Using a random-effects model, the C-allele and the C/C genotype were associated with MS (OR = 1.11, 95% CI = 1.04-1.19, P = 0.001 for the C-allele; OR = 1.15, 95% CI = 1.06-1.24, P = 0.0009 for the C/C genotype). The C/C + C/T genotype was also associated with MS using a fixed-effects model (OR = 1.15, 95% CI = 1.05-1.26, P = 0.003). There was no significant publication bias among the selected studies according to the funnel plot. We also performed the analysis on a European subgroup. This revealed an association between IL7R T244I and MS (P < 0.00001 for the C-allele and the C/C genotype; P = 0.0004 for the C/C + C/T genotype), no heterogeneity was observed (allele C: P = 0.07; genotype C/C: P = 0.10). In conclusion, the meta-analysis demonstrated that the IL7R T244I polymorphism was associated with susceptibility to MS.

A transcription factor map as revealed by a genome-wide gene expression analysis of whole-blood mRNA transcriptome in multiple sclerosis

Background

Several lines of evidence suggest that transcription factors are involved in the pathogenesis of Multiple Sclerosis (MS) but complete mapping of the whole network has been elusive. One of the reasons is that there are several clinical subtypes of MS and transcription factors that may be involved in one subtype may not be in others. We investigate the possibility that this network could be mapped using microarray technologies and contemporary bioinformatics methods on a dataset derived from whole blood in 99 untreated MS patients (36 Relapse Remitting MS, 43 Primary Progressive MS, and 20 Secondary Progressive MS) and 45 age-matched healthy controls.

Methodology/Principal Findings

We have used two different analytical methodologies: a non-standard differential expression analysis and a differential co-expression analysis, which have converged on a significant number of regulatory motifs that are statistically overrepresented in genes that are either differentially expressed (or differentially co-expressed) in cases and controls (e.g., V$KROX_Q6, p-value <3.31E-6; V$CREBP1_Q2, p-value <9.93E-6, V$YY1_02, p-value <1.65E-5).

Conclusions/Significance

Our analysis uncovered a network of transcription factors that potentially dysregulate several genes in MS or one or more of its disease subtypes. The most significant transcription factor motifs were for the Early Growth Response EGR/KROX family, ATF2, YY1 (Yin and Yang 1), E2F-1/DP-1 and E2F-4/DP-2 heterodimers, SOX5, and CREB and ATF families. These transcription factors are involved in early T-lymphocyte specification and commitment as well as in oligodendrocyte dedifferentiation and development, both pathways that have significant biological plausibility in MS causation.

Transgenic mouse models of multiple sclerosis

Multiple sclerosis (MS) is an inflammatory demyelinating disease affecting the central nervous system (CNS) and a frequent cause of neurological disability in young adults. Multifocal inflammatory lesions in the CNS white matter, demyelination, oligodendrocyte loss, axonal damage, as well as astrogliosis represent the histological hallmarks of the disease. These pathological features of MS can be mimicked, at least in part, using animal models. This review discusses the current concepts of the immune effector mechanisms driving CNS demyelination in murine models. It highlights the fundamental contribution of transgenesis in identifying the mediators and mechanisms involved in the pathophysiology of MS models.

IL-7Rα confers susceptibility to experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is a neurological disorder that causes paralysis in young adults and affects women more frequently than men. The etiology of MS is not known, but it is generally viewed as an autoimmune disease of the central nervous system (CNS), influenced by genetic and environmental factors. Recent studies have identified interleukin-7 receptor α (IL-7Rα) as a risk factor for MS. But the role of IL-7Rα in experimental autoimmune encephalomyelitis (EAE) model of MS is not known. In this study we demonstrate that IL-7Rα-deficient (IL-7Rα(-/-)) mice remain resistant to MOGp35-55-induced EAE. When compared with C57BL/6 wild-type mice, IL-7Rα(-/-) mice showed less severe inflammation and demyelination in the CNS. The attenuation of EAE in IL-7Rα(-/-) mice was associated with a decrease in T-helper (Th) 1 and Th17 responses in the CNS and lymphoid organs. IL-7Rα(-/-) mice also showed an increase in Th2 response and CD4(+)Foxp3(+) regulatory T cells. These findings highlight that IL-7Rα confers susceptibility by influencing autoimmune Th1/Th17 responses in EAE model of MS.

A method for simple and accurate identification of the multiple sclerosis associated allele HLA-DRB1*1501 in neuroscience research laboratories

Research on multiple sclerosis (MS) frequently requires typing for allele HLA-DRB1*1501, which the complexities of the HLA system can restrict to specialised histocompatibility laboratories. To overcome this limitation, we have implemented a simple, robust and highly specific method for DRB1*1501 detection. One single-tube polymerase-chain reaction (PCR) per DNA sample allows for detecting DR2 individuals. The spare PCR products of these are then sequenced to identify allele DRB1*1501 by comparison with the official, publicly accessible HLA database. This approach, much simpler than previously available methods, should facilitate research on MS by making accurate identification of DRB1*1501 accessible to neuroscience laboratories.

The double-edged sword of autoimmunity: lessons from multiple sclerosis

The relationship between immune responses to self-antigens and autoimmune disease is unclear. In contrast to its animal model experimental autoimmune encephalomyelitis (EAE), which is driven by T cell responses to myelin antigens, the target antigen of the intrathecal immune response in multiple sclerosis (MS) has not been identified. Although the immune response in MS contributes significantly to tissue destruction, the action of immunocompetent cells within the central nervous system (CNS) may also hold therapeutic potential. Thus, treatment of MS patients with glatiramer acetate triggers a protective immune response. Here we review the immunopathogenesis of MS and some recent findings on the mechanism of glatiramer acetate (GA).

Necrotizing meningoencephalitis of Pug dogs associates with dog leukocyte antigen class II and resembles acute variant forms of multiple sclerosis

Necrotizing meningoencephalitis (NME) is a disorder of Pug Dogs that appears to have an immune etiology and high heritability based on population studies. The present study was undertaken to identify a genetic basis for the disease. A genome-wide association scan with single tandem repeat (STR) markers showed a single strong association near the dog leukocyte antigen (DLA) complex on CFA12. Fine resolution mapping with 27 STR markers on CFA12 further narrowed association to the region containing DLA-DRB1, -DQA1 and, -DQB1 genes. Sequencing confirmed that affected dogs were more likely to be homozygous for specific alleles at each locus and that these alleles were linked, forming a single high risk haplotype. The strong DLA class II association of NME in Pug Dogs resembles that of human multiple sclerosis (MS). Like MS, NME appears to have an autoimmune basis, involves genetic and nongenetic factors, has a relatively low incidence, is more frequent in females than males, and is associated with a vascularly orientated nonsuppurative inflammation. However, NME of Pug Dogs is more aggressive in disease course than classical human MS, appears to be relatively earlier in onset, and involves necrosis rather than demyelination as the central pathobiologic feature. Thus, Pug Dog encephalitis (PDE) shares clinical features with the less common acute variant forms of MS. Accordingly, NME of Pug Dogs may represent a naturally occurring canine model of certain idiopathic inflammatory disorders of the human central nervous system.

Influence of HLA-DRB1 allele heterogeneity on disease risk and clinical course in a West Australian MS cohort: a high-resolution genotyping study

Background: Previous studies on the influence of HLA-DRB1 alleles on multiple sclerosis (MS) susceptibility and clinical course have mostly employed the 2-point genotyping method.

Objective: To assess the influence of HLA-DRB1 alleles and allele interactions on disease risk and clinical course in a large West Australian MS patient cohort using high-resolution genotyping.

Methods: Four digit HLA-DRB1 genotyping was performed on a group of 466 clinically definite or probable MS patients from the Perth Demyelinating Diseases Database and 189 healthy Caucasian controls from the Busselton Community Health Study.

Results: In addition to the known risk allele HLA-DRB1*1501, evidence of increased susceptibility to MS was found for three additional alleles, DRB1*0405, DRB1*1104 and DRB1*1303, though the power was insufficient to sustain significance for these when crudely Bonferroni corrected over all alleles considered. DRB1*0701 was found to be protective even after correction for multiple comparisons. In addition we found evidence that the DRB1*04 sub-allele HLA-DRB1*0407 and HLA-DRB1*0901 may be protective. Among the diplotypes, the highest estimated risk was in HLA-DRB1*1501/*0801 heterozygotes and DRB1*1501 homozygotes and the lowest in HLA-DRB1*0701/*0101 heterozygotes. There was no significant gender association with HLA-DRB1*1501 overall, but the HLA-DRB1*1501/*1104 risk genotype was significantly associated with female gender. HLA-DRB1*1501 was the strongest risk allele in both primary progressive MS and relapsing—remitting MS.

Conclusion: Our results demonstrate the advantages of high-resolution HLA genotyping in recognizing risk-modifying alleles and allele combinations in this patient cohort and in recognizing the differential effects of HLA-DRB1*04 and DRB1*11 sub-alleles.

The type 1 diabetes - HLA susceptibility interactome--identification of HLA genotype-specific disease genes for type 1 diabetes

Background

The individual contribution of genes in the HLA region to the risk of developing type 1 diabetes (T1D) is confounded by the high linkage disequilibrium (LD) in this region. Using a novel approach we have combined genetic association data with information on functional protein-protein interactions to elucidate risk independent of LD and to place the genetic association into a functional context.

Methodology/Principal Findings

Genetic association data from 2300 single nucleotide polymorphisms (SNPs) in the HLA region was analysed in 2200 T1D family trios divided into six risk groups based on HLA-DRB1 genotypes. The best SNP signal in each gene was mapped to proteins in a human protein interaction network and their significance of clustering in functional network modules was evaluated. The significant network modules identified through this approach differed between the six HLA risk groups, which could be divided into two groups based on carrying the DRB1*0301 or the DRB1*0401 allele. Proteins identified in networks specific for DRB1*0301 carriers were involved in stress response and inflammation whereas in DRB1*0401 carriers the proteins were involved in antigen processing and presentation.

Conclusions/Significance

In this study we were able to hypothesise functional differences between individuals with T1D carrying specific DRB1 alleles. The results point at candidate proteins involved in distinct cellular processes that could not only help the understanding of the pathogenesis of T1D, but also the distinction between individuals at different genetic risk for developing T1D.

Regulation of major histocompatibility complex class II gene expression, genetic variation and disease

Major histocompatibility complex (MHC) class II molecules are central to adaptive immune responses and maintenance of self-tolerance. Since the early 1970s, the MHC class II region at chromosome 6p21 has been shown to be associated with a remarkable number of autoimmune, inflammatory and infectious diseases. Given that a full explanation for most MHC class II disease associations has not been reached through analysis of structural variation alone, in this review we examine the role of genetic variation in modulating gene expression. We describe the intricate architecture of the MHC class II regulatory system, indicating how its unique characteristics may relate to observed associations with disease. There is evidence that haplotype-specific variation involving proximal promoter sequences can alter the level of gene expression, potentially modifying the emergence and expression of key phenotypic traits. Although much emphasis has been placed on cis-regulatory elements, we also examine the role of more distant enhancer elements together with the evidence of dynamic inter- and intra-chromosomal interactions and epigenetic processes. The role of genetic variation in such mechanisms may hold profound implications for susceptibility to common disease.