Revealing the genetic basis of multiple sclerosis: are we there yet?

Identification of Key Ferroptosis-Related Genes in the Peripheral Blood of Patients with Relapsing-Remitting Multiple Sclerosis and Its Diagnostic Value

Multiple sclerosis (MS) is a neurodegenerative disease with a complex pathogenesis. Re-lapsing-remitting multiple sclerosis (RRMS) is the most common subset of MS, accounting for approximately 85% of cases. Recent studies have shown that ferroptosis may contribute to the progression of RRMS, but the underlying mechanism remains to be elucidated. Herein, this study intended to explore the molecular network of ferroptosis associated with RRMS and establish a predictive model for efficacy diagnosis. Firstly, RRMS-related module genes were identified using weighted gene co-expression network analysis (WGCNA). Secondly, the optimal machine learning model was selected from four options: the generalized linear model (GLM), random forest model (RF), support vector machine model (SVM), and extreme gradient boosting model (XGB). Subsequently, the predictive efficacy of the diagnostic model was evaluated using receiver operator characteristic (ROC) analysis. Finally, a SVM diagnostic model based on five genes (JUN, TXNIP, NCOA4, EIF2AK4, PIK3CA) was established, and it demonstrated good predictive performance in the validation dataset. In summary, our study provides a systematic exploration of the complex relationship between ferroptosis and RRMS, which may contribute to a better understanding of the role of ferroptosis in the pathogenesis of RRMS and provide promising diagnostic strategies for RRMS patients.

Microbiome Methods in Experimental Autoimmune Encephalomyelitis

Microbiome composition studies are increasingly shedding light on animal models of disease. This paper describes a protocol for analyzing the gut microbiome composition prior to and after the induction of mice to experimental autoimmune encephalomyelitis (EAE), the principal animal model of the human neuroinflammatory demyelinating disease multiple sclerosis (MS). We also address and provide data assessing the impact of mice reared in different animal facilities on EAE induction. Furthermore, we discuss potential regulators of the gut-microbiome-brain axis (GMBA) in relation to neuroinflammation and implications on demyelinating disease states. Our results suggest that mice reared in different animal facilities produce different levels of EAE induction. These results highlight the importance of accounting for consistent environmental conditions when inducing EAE and other animal models of disease. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Study of the composition of the gut microbiome in the neuroinflammatory model of experimental autoimmune encephalomyelitis Basic Protocol 2: Experimental procedures for DNA extraction and microbiome analysis.

The trend of incidence, prevalence, and DALY of multiple sclerosis in the Middle East and Northern Africa region compared to global, West Europe and, Iran's corresponding values during 1990-2017: Retrieved from global burden of diseases data

BACKGROUND

Multiple sclerosis (MS) is the most common immune mediated disorder of the central nervous system (CNS). This study compares the worldwide occurrence and epidemiologic burden of MS in the Middle East and Northern Africa (MENA) region and Western Europe from 1990 to 2017.

METHODS

This study used data from the global burden of disease (GBD) studies. Initially, all age and age-specific values were estimated and then, these values were compared among the mentioned areas. In addition, the changes of sex distribution of MS according to incidence, prevalence, and disability-adjusted life years (DALYs) were calculated. The trend of MS incidence was also compared among the MENA region countries.

RESULTS

According to MS incidence per 100,000 populations during 1990 to 2017, the occurrence of new cases has decreased slightly in the world (from 0.7 to 0.65) and Western Europe (from 2.55 to 2.50). Except Iran with a sharp rise of 2 to 2.8, there was a slow increase in the MENA region (from 0.9 to 1). The MS prevalence, between 1990 and 2017, in all ages was stable in the world and the MENA region except a steady increase in Iran and highest value in Western Europe. In this study, we determined the age-specific incidence of MS in all regions from 1990 to 2017. Although data showed a different trend of changes between age groups and regions, the group age 25-29 years had the highest risk of MS incidence. Based on gender, the incidence, prevalence, and DALY of MS in all regions were higher in female.

CONCLUSION

From 1990 to 2017, Western Europe had the highest MS prevalence and the MENA region had a relatively stable trend for MS incidence. In particular, in Iran, the MS incidence has been constantly increasing and has surpassed Western Europe since 2013.

An overview of lipidomic analysis in different human matrices of multiple sclerosis

Multiple sclerosis is a chronic inflammatory and neurodegenerative disease of the central nervous system, and it is one of the most common neurological cause of disability in young adults. It is known that several factors contribute to increase the risk of development and pathogenesis of multiple sclerosis, nonetheless, but the true etiology of this pathology remains unknown. Similar to other inflammatory diseases, oxidative stress and lipid peroxidation are also associated to multiple sclerosis. Alterations in the lipid profile seem to be a hallmark of this pathology which can contribute to the dysregulation of lipid homeostasis and lipid metabolism in multiple sclerosis. Lipidomic studies analysed in this review clearly demonstrate the role of lipids in inflammatory processes, in immunity, and in the onset and development of multiple sclerosis. Several investigations reported alterations of some molecular lipid species, in particular, with decrease of fatty acids (FA) 18:2 and 20:4 and total polyunsaturated FA, with compensatory increases of saturated FA with shorter carbon chains. Oxidized phospholipids were reported in few studies as well. Also, it was shown that clinical lipidomics has potential as a tool to aid both in multiple sclerosis diagnosis and therapeutics by allowing a detailed lipidome profiling of the patients suffering with this disease.

A Network-Based Bioinformatics Approach to Identify Molecular Biomarkers for Type 2 Diabetes that Are Linked to the Progression of Neurological Diseases

Neurological diseases (NDs) are progressive disorders, the progression of which can be significantly affected by a range of common diseases that present as comorbidities. Clinical studies, including epidemiological and neuropathological analyses, indicate that patients with type 2 diabetes (T2D) have worse progression of NDs, suggesting pathogenic links between NDs and T2D. However, finding causal or predisposing factors that link T2D and NDs remains challenging. To address these problems, we developed a high-throughput network-based quantitative pipeline using agnostic approaches to identify genes expressed abnormally in both T2D and NDs, to identify some of the shared molecular pathways that may underpin T2D and ND interaction. We employed gene expression transcriptomic datasets from control and disease-affected individuals and identified differentially expressed genes (DEGs) in tissues of patients with T2D and ND when compared to unaffected control individuals. One hundred and ninety seven DEGs (99 up-regulated and 98 down-regulated in affected individuals) that were common to both the T2D and the ND datasets were identified. Functional annotation of these identified DEGs revealed the involvement of significant cell signaling associated molecular pathways. The overlapping DEGs (i.e., seen in both T2D and ND datasets) were then used to extract the most significant GO terms. We performed validation of these results with gold benchmark databases and literature searching, which identified which genes and pathways had been previously linked to NDs or T2D and which are novel. Hub proteins in the pathways were identified (including DNM2, DNM1, MYH14, PACSIN2, TFRC, PDE4D, ENTPD1, PLK4, CDC20B, and CDC14A) using protein-protein interaction analysis which have not previously been described as playing a role in these diseases. To reveal the transcriptional and post-transcriptional regulators of the DEGs we used transcription factor (TF) interactions analysis and DEG-microRNAs (miRNAs) interaction analysis, respectively. We thus identified the following TFs as important in driving expression of our T2D/ND common genes: FOXC1, GATA2, FOXL1, YY1, E2F1, NFIC, NFYA, USF2, HINFP, MEF2A, SRF, NFKB1, USF2, HINFP, MEF2A, SRF, NFKB1, PDE4D, CREB1, SP1, HOXA5, SREBF1, TFAP2A, STAT3, POU2F2, TP53, PPARG, and JUN. MicroRNAs that affect expression of these genes include mir-335-5p, mir-16-5p, mir-93-5p, mir-17-5p, mir-124-3p. Thus, our transcriptomic data analysis identifies novel potential links between NDs and T2D pathologies that may underlie comorbidity interactions, links that may include potential targets for therapeutic intervention. In sum, our neighborhood-based benchmarking and multilayer network topology methods identified novel putative biomarkers that indicate how type 2 diabetes (T2D) and these neurological diseases interact and pathways that, in the future, may be targeted for treatment.

Epstein Barr virus nuclear antigen 1 (EBNA-1) peptides recognized by adult multiple sclerosis patient sera induce neurologic symptoms in a murine model

Multiple sclerosis (MS) is an autoimmune demyelinating disease with progressive neurodegeneration and complex etiology likely involving genetic and environmental factors. MS has been associated with Epstein Barr virus (EBV) infection, with patients often showing enhanced responses to EBV antigens. To determine whether abnormal EBV nuclear antigen-1 (EBNA-1) humoral immunity can serve as an initiator of autoimmune responses in MS, we investigated the fine specificities of the humoral immune response against EBNA-1 in MS patients using solid phase epitope mapping. Antibodies from MS patients recognized an EBNA-1 epitope spanning amino acids 411-426, previously unknown to be recognized specifically by untreated MS patients. Antibodies against this epitope cross-reacted to myelin basic protein (MBP). Furthermore, animals immunized with this EBNA-1 polypeptide mounted a response against MBP and developed signs of experimental autoimmune encephalitis (EAE). These data support a link between MS and EBV through antibodies that cross-react between EBV proteins and the MBP autoantigen.

Epstein-Barr Virus and miRNAs: Partners in Crime in the Pathogenesis of Multiple Sclerosis?

MicroRNAs (miRNAs) are small non-coding RNAs that modulate gene expression post transcriptionally. In healthy individuals, miRNAs contribute to maintaining gene expression homeostasis. However, the level of miRNAs expressed is markedly altered in different diseases, including multiple sclerosis (MS). The impact of such changes is being investigated, and thought to shape the immune system into the inflammatory autoimmune phenotype. Much is yet to be learned about the contribution of miRNAs in the molecular pathology of MS. Epstein-Barr virus (EBV) infection is a major risk factor for the development of MS. EBV encodes more than 40 miRNAs, most of which have been studied in the context of EBV associated cancers. These viral miRNAs regulate genes involved in cell apoptosis, antigen presentation and recognition, as well as B cell transformation. If EBV infection contributes to the pathology of MS, it is plausible that EBV miRNAs may be involved. Unfortunately, there are limited studies addressing how EBV miRNAs are involved in the pathogenesis of MS. This review summarizes what has been reported regarding cellular and viral miRNA profiles in MS and proposes possible interactions between the two in the development of MS.

Computational modeling of brain pathologies: the case of multiple sclerosis

The central nervous system is the most complex network of the human body. The existence and functionality of a large number of molecular species in human brain are still ambiguous and mostly unknown, thus posing a challenge to Science and Medicine. Neurological diseases inherit the same level of complexity, making effective treatments difficult to be found. Multiple sclerosis (MS) is a major neurological disease that causes severe inabilities and also a significant social burden on health care system: between 2 and 2.5 million people are affected by it, and the cost associated with it is significantly higher as compared with other neurological diseases because of the chronic nature of the disease and to the partial efficacy of current therapies. Despite difficulties in understanding and treating MS, many computational models have been developed to help neurologists. In the present work, we briefly review the main characteristics of MS and present a selection criteria of modeling approaches.

Novel SNARE Complex Polymorphisms Associated with Multiple Sclerosis: Signs of Synaptopathy in Multiple Sclerosis

Background:

It is well known that axonal degeneration plays a role in disability in patients with multiple sclerosis, and synaptopathy has recently become an important issue.

Aims:

To investigate the possible roles of selected synaptic and presynaptic membrane protein genetic polymorphisms (VAMP2, SNAP-25, synaptotagmin, and syntaxin 1A) in patients with multiple sclerosis.

Study Design:

Case-control study.

Methods:

A total of 123 patients with multiple sclerosis and 192 healthy controls were included. The functional polymorphisms of specific SNARE complex proteins (VAMP2, synaptotagmin XI, syntaxin 1A, and SNAP-25) were analyzed by polymerase chain reaction.

Results:

Significant differences were detected in the genotype and allele distribution of 26-bp Ins/Del polymorphisms of VAMP2 between patients with multiple sclerosis and control subjects; Del/Del genotype and Del allele of VAMP2 were more frequent in patients with multiple sclerosis (p=0.011 and p=0.004, respectively). Similarly, Ddel polymorphism of SNAP-25 gene C/C genotype (p=0.059), syntaxin 1A T/C and C/C genotypes (p=0.005), and synaptotagmin XI gene C allele (p=0.001) were observed more frequently in patients with multiple sclerosis. CC, syntaxin rs1569061 1A gene for 33-bp promoter region TC haplotypes, and synaptotagmin XI gene were found to be associated with an increased risk for multiple sclerosis (p=0.012). Similarly, GC haplotype for rs3746544 of SNAP-25 gene and rs1051312 of SNAP-25 gene were associated with an increased risk for multiple sclerosis (p=0.022).

Conclusion:

Genetic polymorphisms of SNARE complex proteins, which have critical roles in synaptic structure and communication, may play a role in the development of multiple sclerosis.

Can the Fact That Myelin Proteins Are Old and Break down Explain the Origin of Multiple Sclerosis in Some People?

Recent discoveries may change the way that multiple sclerosis (MS) is viewed, particularly with regard to the reasons for the untoward immune response. The fact that myelin proteins are long-lived, and that by the time we are adults, they are extensively degraded, alters our perspective on the reasons for the onset of autoimmunity and the origin of MS. For example, myelin basic protein (MBP) from every human brain past the age of 20 years, is so greatly modified, that it is effectively a different protein from the one that was laid down in childhood. Since only a subset of people with such degraded MBP develop MS, a focus on understanding the mechanism of immune responses to central nervous system (CNS) antigens and cerebral immune tolerance appear to be worthwhile avenues to explore. In accord with this, it will be productive to examine why all people, whose brains contain large quantities of a "foreign antigen", do not develop MS. Importantly for the potential causation of MS, MBP from MS patients breaks down differently from the MBP in aged controls. If the novel structures formed in these MS-specific regions are particularly antigenic, it could help explain the origin of MS. If verified, these findings could provide an avenue for the rational synthesis of drugs to prevent and treat MS.

The Non-Obese Diabetic Mouse Strain as a Model to Study CD8(+) T Cell Function in Relapsing and Progressive Multiple Sclerosis

Multiple sclerosis (MS) is a neurodegenerative disease resulting from an autoimmune attack on central nervous system (CNS) myelin. Although CD4⁺ T cell function in MS pathology has been extensively studied, there is also strong evidence that CD8⁺ T lymphocytes play a key role. Intriguingly, CD8⁺ T cells accumulate in great numbers in the CNS in progressive MS, a form of the disease that is refractory to current disease-modifying therapies that target the CD4⁺ T cell response. Here, we discuss the function of CD8⁺ T cells in experimental autoimmune encephalomyelitis (EAE), a mouse model of MS. In particular, we describe EAE in non-obese diabetic (NOD) background mice, which develop a pattern of disease characterized by multiple attacks and remissions followed by a progressively worsening phase. This is highly reminiscent of the pattern of disease observed in nearly half of MS patients. Particular attention is paid to a newly described transgenic mouse strain (1C6) on the NOD background whose CD4⁺ and CD8⁺ T cells are directed against the encephalitogenic peptide MOG_[35–55]. Use of this model will give us a more complete picture of the role(s) played by distinct T cell subsets in CNS autoimmunity.

The POLG Polyglutamine Tract Variants in Iranian Patients with Multiple Sclerosis

OBJECTIVE

Multiple Sclerosis (MS) is a common disease of the central nervous system. The interaction between inflammatory and neurodegenerative processes typically results in irregular neurological disturbances followed by progressive disability. Mitochondrial dysfunction has been implicated in neurodegenerative disorders. The DNA polymerase-gamma (POLG) gene, which encodes the catalytic subunit of enzyme responsible for directing mtDNA replication, contains a poly glutamine tract (poly-Q) in the N-terminal, encoded by a CAG sequence in exon 2.

MATERIALS & METHODS

We analyzed the POLG trinucleotide repeats in 40 Iranian patients with MS (27 females and 13 males with an age range of 18-55); and 47 healthy age, gender, and ethnic matched controls were chosen by PCR-SSCP analysis.

RESULTS

Our results indicated that the most common allele in patients had 10 consecutive CAG repeats (10Q). Other alleles of 11and 12 trinucleotide repeats were detected. We did not find any difference between the CAG repeat length distribution in controls and MS patients.

CONCLUSION

No correlation was observed in the POLG gene CAG repeat with pathogenesis of MS, but it looks that other point mutations in POLG gene may have an important role in the disease's pathogenesis and produced more significant results.

Autoimmune disease prevalence in a multiple sclerosis cohort in Argentina

Background. Comorbid autoimmune diseases in MS patients have been studied extensively with controversial results. Moreover, no such data exists for Latin-American MS patients. Methods. We conducted a case-control study aimed to establish the prevalence of autoimmune disorders in a cohort of Argentinean MS patients. Results. There were no significant differences in autoimmune disease prevalence in MS patients with respect to controls. The presence of one or more autoimmune disorders did not increase risk of MS (OR 0.85, 95% CI 0.6-1.3). Discussion. Our results indicate absence of increased comorbid autoimmune disease prevalence in MS patients, as well as of increased risk of MS in patients suffering from other autoimmune disorders.

Oligodendrogenesis in the normal and pathological central nervous system

Oligodendrocytes (OLGs) are generated late in development and myelination is thus a tardive event in the brain developmental process. It is however maintained whole life long at lower rate, and myelin sheath is crucial for proper signal transmission and neuronal survival. Unfortunately, OLGs present a high susceptibility to oxidative stress, thus demyelination often takes place secondary to diverse brain lesions or pathologies. OLGs can also be the target of immune attacks, leading to primary demyelination lesions. Following oligodendrocytic death, spontaneous remyelination may occur to a certain extent. In this review, we will mainly focus on the adult brain and on the two main sources of progenitor cells that contribute to oligodendrogenesis: parenchymal oligodendrocyte precursor cells (OPCs) and subventricular zone (SVZ)-derived progenitors. We will shortly come back on the main steps of oligodendrogenesis in the postnatal and adult brain, and summarize the key factors involved in the determination of oligodendrocytic fate. We will then shed light on the main causes of demyelination in the adult brain and present the animal models that have been developed to get insight on the demyelination/remyelination process. Finally, we will synthetize the results of studies searching for factors able to modulate spontaneous myelin repair.

Investigation of gene-gene interactions between CD40 and CD40L in Polish multiple sclerosis patients

CD40-CD40L interaction is necessary for the activation of both humoral and cellular immune response and has been suggested to play a role in the pathogenesis of multiple sclerosis (MS). Therefore, we analyzed the combined influence of the CD40 and CD40L variants on MS susceptibility and progression on well-defined Polish population. Our investigation revealed that CT individuals in rs1883832 locus of CD40 possessed almost 1.5-fold higher risk for MS than CC individuals (OR = 1.44; 95%CI = 1.03-2.1; p = 0.032), while this risk for TT individuals was almost 2.5-fold higher (OR = 2.36; 95%CI = 1.19-4.78; p = 0.014). Moreover, for the first time, we observed the association of CD40 gene with MS development and progression. We observed that for the rs1883832CC individuals the age at diagnosis was on average 2 years lower than for the rs1883832CT and rs1883832TT individuals (CI95% = -3.69-(-0.29); p = 0.023). Additionally, we detected that individuals with TT and CT genotypes showed lower risk of developing secondary progressive course in comparison to those with CC genotype. For rs1883832TT individuals this risk was 4-fold lower (HR = 0.24; CI95% = 0.10-0.53; p = 0.00062). Despite the fact that CD40-CD40L pathway plays a key role in development of autoimmune diseases, we were not able to detect gene-gene interactions between CD40 and CD40L polymorphisms associated with multiple sclerosis.

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.

Describing the development of molecular research in the context of nervous system diseases using year-based h-cores

This article introduces year-based h-indices as a tool to produce easy-to-use research overviews. Based on PubMed data, a general framework is constructed to study the development of molecular research in the context of nervous system diseases. It is shown which molecular substances are the centre of attention and which have passed their peak. Year-based h-indices have the following interesting features for representing changes in a field or discipline: flexibility, sensitivity to dynamic changes, fluctuation detection and trend detection.

MAPT gene rs1052553 variant is not associated with the risk for multiple sclerosis

BACKGROUND/OBJECTIVES

Some experimental data suggest a possible role of tau protein in the pathogenesis of multiple sclerosis (MS) and in experimental autoimmune encephalomyelitis. The aim of this study was to investigate a possible influence of the SNP rs1052553 in the MAPT gene in the risk for relapsing bout onset (relapsing-remitting and secondary progressive) MS.

METHODS

We analyzed the allelic and genotype frequency of MAPT rs1052553, which has been associated with some neurodegenerative diseases, in 259 patients with relapsing bout onset MS and 291 healthy controls, using TaqMan Assays.

RESULTS

MAPT rs1052553 allelic and genotype frequencies did not differ significantly between relapsing bout onset MS patients and controls, and were unrelated with the age of onset of MS or gender.

CONCLUSIONS

These results suggest that MAPT rs1052553 polymorphism is not related with the risk for relapsing bout onset MS.

Vitamin D3 receptor ( VDR ) gene rs2228570 (Fok1) and rs731236 (Taq1) variants are not associated with the risk for multiple sclerosis: results of a new study and a meta-analysis

Background

Some epidemiological, genetic, and experimental data suggest a possible role of vitamin D in the pathogenesis of multiple sclerosis (MS) and in experimental autoimmune encephalomyelitis. Data on the possible contribution of several single nucleotide polymorphisms (SNP) in the vitamin D receptor (VDR) gene to the risk for MS are controversial. Several studies suggested an interaction between some SNPs in the VDR gene and HLADRB1*1501 in the risk for MS.

Objectives

The aim of this study was to investigate a possible influence of the SNPs rs2228570 and rs731236 in the VDR gene in the risk for MS. A secondary objective was to address the possible interactions between VDR genes and HLADRB1*1501.

Methods

We analyzed the allelic and genotype frequency of VDR rs2228570, rs731236, and HLADRB1*1501 (rs3135388) in 303 patients with MS and 310 healthy controls, using TaqMan Assays. We also conducted a meta-analysis, that was carried out by using the software Meta-Disc 1.1.1 (http://www.hrc.es/investigacion/metadisc.html; Unit of Clinical Statistics, Hospital Ramón y Cajal, Madrid, Spain). Heterogeneity between studies in terms of degree of association was tested using the Q-statistic.

Results

VDR rs2228570 and rs731236 allelic and genotype frequencies did not differ significantly between MS patients and controls, and were unrelated with the age of onset of MS, gender, and course of MS. HLADRB1*1501 showed a high association with the risk of developing MS 4.76(95% C.I.  = 3.14–7.27; p<0.0001). The meta-analysis, after excluding data of one study that was responsible of heterogeneity for rs731236 polymorphism, showed lack of relation of both SNPs with the risk for MS. HLADRB1*1501 showed lack of interaction with VDR rs2228570 and rs731236 in increasing MS risk.

Conclusions

These results suggest that VDR rs2228570 and rs731236 polymorphisms are not related with the risk for MS, and did not confirm interaction between these VDR SNPs and HLADRB1 in the risk for MS.

LINGO1 rs9652490 and rs11856808 polymorphisms are not associated with risk for multiple sclerosis

BACKGROUND

Some recent experimental data suggest a possible role of LINGO-1 in the pathogenesis of multiple sclerosis (MS). In an attempt to identify genetic biomarkers related to MS susceptibility, we genotyped two common SNPs in the LINGO1 gene which have been associated to other neurological conditions, in patients with MS and in healthy subjects. These SNPs are linked to several SNPs within the LINGO1 gene, especially in individuals of Oriental or Caucasian descent.

METHODS

We analyzed the allelic and genotype frequency of two LINGO1 variants (rs9652490 and rs11856808) in 293 patients with MS and 318 healthy controls, using KASPar assays.

RESULTS

LINGO1 rs9652490 and rs11856808 allelic and genotype frequencies did not differ significantly between MS patients and controls. The minor allele frequencies for rs9652490 were 0.171 (95% CI = 0.140-0.201) and 0.167 (95% CI = 0.138-0.196 for cases and controls respectively (p = 0.853). For rs11856808 the minor allele frequencies were 0.317 (95% CI = 0.280-0.355) and 0.310 (95% CI = 0.274-0.346) for cases and controls, respectively (p = 0.773). Allele and genotype frequencies were unrelated with the age of onset of MS, gender, and clinical course of MS. In addition, haplotype analyses did not reveal any putative risk related to haplotypes.

CONCLUSIONS

These results suggest that LINGO1 rs9652490 and rs11856808 polymorphisms are not related with risk for MS. This study adds to other published evidence indicating that, to date, the LINGO1 SNPs studied here could be useful risk biomarkers of developing essential tremor, but not other movement disorders.

Epigenetic mechanisms in multiple sclerosis: implications for pathogenesis and treatment

Clinical neurologists and scientists who study multiple sclerosis face open questions regarding the integration of epidemiological data with genome-wide association studies and clinical management of patients. It is becoming evident that the interplay of environmental influences and individual genetic susceptibility modulates disease presentation and therapeutic responsiveness. The molecular mechanisms through which environmental signals are translated into changes in gene expression include DNA methylation, post-translational modification of nucleosomal histones, and non-coding RNAs. These mechanisms are regulated by families of specialised enzymes that are tissue selective and cell-type specific. A model of multiple sclerosis pathogenesis should integrate underlying risk related to genetic susceptibility with cell-type specific epigenetic changes occurring in the immune system and in the brain in response to ageing and environmental stimuli.

ALCAM--novel multiple sclerosis locus interfering with HLA-DRB1*1501

Activated leukocyte cell adhesion molecule (ALCAM) is a molecule involved in leukocyte migration across the blood-brain barrier which is a key stage in multiple sclerosis (MS) pathogenesis. The present study is the first to report evidence of the association of rs6437585 ALCAM polymorphism with risk and progression of MS. Our investigation revealed that rs6437585CT individuals had higher risk of MS (OR=2.34; 95%CI=1.22-4.51; P=0.011) and over 2 years earlier age of onset (95%CI=0.16-4.41, P=0.036). Moreover, we demonstrated that two ALCAM polymorphisms, rs11559013 and rs34926152, although not associated with MS itself, modify HLA-DRB1*1501 effect. Results obtained from logistic regression analysis showed five-fold lower risk for MS for both rs11559013GA/HLA-DRB1*1501+ and rs34926152GT/HLA-DRB1*1501+ individuals. This observations may suggest protective role against MS for both rs11559013GA and rs34926152GT genotypes in HLA-DRB1*1501 positive individuals.

Mechanisms and pathophysiology of autoimmune disease

The first textbook on autoimmunity was published by Ian Mackay and McFarland Burnett in 1963. It was the first attempt to summarize existing knowledge on human autoimmunity. Since that time, there have been tens of thousands of experimental papers and numerous textbooks that focus on the diagnosis and treatment of human autoimmunity. There have been at least as many, if not more, directed at similar issues in animal models. Enormous strides have been made not only in diagnosis, but also in the pathophysiology and especially in treatment. We have gone from the era of simple HLA typing to deep sequencing and, more recently, epigenetic analysis. We have gone from the era of white blood cell differentials to detailed lymphoid phenotyping. We have gone from the era of simple antinuclear antibodies to detailed and sophisticated immunodiagnosis with recombinant autoantigens and disease-specific epitopes. We have gone from the era of using only corticosteroids to selective biologic agents. Diseases that were previously considered idiopathic are now very much understood as autoimmune. We are in the era of autoinflammatory reactions and the concept of both innate versus adaptive immunity in mediating immunopathology. In this edition of Clinical Reviews in Allergy and Immunology, we focus on key and cutting-edge issues in the pathophysiology of autoimmunity. The issues are very much oriented and driven by hypothesis, i.e., a prediction of events expected to occur based on observations. It is not meant to be a complete summary of potential mechanisms of autoimmunity, but rather an attempt to accelerate discussion and better understanding. The primary goal is obviously to help our patients with autoimmune disease.

Emerging patterns of genetic overlap across autoimmune disorders

Most of the recently identified autoimmunity loci are shared among multiple autoimmune diseases. The pattern of genetic association with autoimmune phenotypes varies, suggesting that certain subgroups of autoimmune diseases are likely to share etiological similarities and underlying mechanisms of disease. In this review, we summarize the major findings from recent studies that have sought to refine genotype-phenotype associations in autoimmune disease by identifying both shared and distinct autoimmunity loci. More specifically, we focus on information from recent genome-wide association studies of rheumatoid arthritis, ankylosing spondylitis, celiac disease, multiple sclerosis, systemic lupus erythematosus, type 1 diabetes and inflammatory bowel disease. Additional work in this area is warranted given both the opportunity it provides to elucidate pathogenic mechanisms in autoimmunity and its potential to inform the development of improved diagnostic and therapeutic tools for this group on complex human disorders.

HLA-DRB1*15:01 and multiple sclerosis: a female association?

BACKGROUND

The association between multiple sclerosis (MS) and the HLA-DRB1*15:01 haplotype has been proven to be strong, but its molecular basis remains unclear. Vitamin D receptor (VDR) gene variants and sex have been proposed to modulate this association.

OBJECTIVES

1) Test the association of MS with *15:01 and VDR variants; 2) check whether VDR variants and/or sex modulate the risk conferred by *15:01; 3) study whether *15:01, VDR variants and/or sex affect HLA II gene expression.

METHODS

Peripheral blood from 364 MS patients and 513 healthy controls was obtained and DNA and total RNA were extracted from leukocytes. HLA-DRB1, DRB5 and DQA1 gene expression measurements and *15:01 genotyping were performed by qPCR. VDR variants were genotyped by PCR-RFLP.

RESULTS

Our data confirms that the *15:01 haplotype confers a higher risk of suffering from MS (OR = 1.364; 95% CI = 1.107-1.681). No association was found between VDR variants and MS, but they were shown to moderately modulate the risk conferred by *15:01. Sex confers a much stronger modulation and the *15:01-MS association seems to be female specific. A higher *15:01 frequency has been observed in Basques (45.1%). *15:01 positive samples showed a significant overexpression of DRB1 (p < 0.001), DRB5 (p < 0.001) and DQA1 (p = 0.004) in patients. DRB1 (p = 0.004) and DRB5 (p < 0.001) were also overexpressed in *15:01 controls.

CONCLUSIONS

We confirm the *15:01-MS association and support that it is female specific. The relevance of ethnic origin on association studies has also been highlighted. HLA-DRB1*15:01 seems to be a haplotype consistently linked to high HLA II gene expression.