Association of susceptibility to multiple sclerosis in Southern Han Chinese with HLA-DRB1, -DPB1 alleles and DRB1-DPB1 haplotypes: distinct from other populations

Autoreactive lymphocytes in multiple sclerosis: Pathogenesis and treatment target

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) characterized by destruction of the myelin sheath structure. The loss of myelin leads to damage of a neuron’s axon and cell body, which is identified as brain lesions on magnetic resonance image (MRI). The pathogenesis of MS remains largely unknown. However, immune mechanisms, especially those linked to the aberrant lymphocyte activity, are mainly responsible for neuronal damage. Th1 and Th17 populations of lymphocytes were primarily associated with MS pathogenesis. These lymphocytes are essential for differentiation of encephalitogenic CD8⁺ T cell and Th17 lymphocyte crossing the blood brain barrier and targeting myelin sheath in the CNS. B-lymphocytes could also contribute to MS pathogenesis by producing anti-myelin basic protein antibodies. In later studies, aberrant function of Treg and Th9 cells was identified as contributing to MS. This review summarizes the aberrant function and count of lymphocyte, and the contributions of these cell to the mechanisms of MS. Additionally, we have outlined the novel MS therapeutics aimed to amend the aberrant function or counts of these lymphocytes.

HLA-DRB1*16:02 is associated with PEG-asparaginase hypersensitivity

Aim: To evaluate the associations between human leukocyte antigen (HLA)-DRB1 variants and the rs6021191 variant in nuclear factor of activated T cells 2 (NFATC2) with PEG-asparaginase hypersensitivity in children with acute lymphoblastic leukemia (ALL) treated according to the Chinese Children Leukemia Group (CCLG) ALL 2018 protocol. Methods: HLA-DRB1 genotyping was performed using a PCR sequence-based typing (SBT) method. NFATC2 rs6021191 was genotyped applying TaqMan Genotyping Assay. Results: T-ALL and higher risk groups were at higher risk for PEG-asparaginase hypersensitivity. No association was found between NFATC2 rs6021191 and PEG-asparaginase hypersensitivity. HLA-DRB1*16:02 variant was associated with PEG-asparaginase allergy both in univariate and multivariate logistic regression analysis. Conclusion: Our results confirm that variations in HLA-DRB1 might influence the development of asparaginase hypersensitivity.

HLA-DPB1*03 as Risk Allele and HLA-DPB1*04 as Protective Allele for Both Early- and Adult-Onset Multiple Sclerosis in a Hellenic Cohort

Background: Human Leucocyte Antigens (HLA) represent the genetic loci most strongly linked to Multiple Sclerosis (MS). Apart from HLA-DR and HLA–DQ, HLA-DP alleles have been previously studied regarding their role in MS pathogenesis, but to a much lesser extent. Our objective was to investigate the risk/resistance influence of HLA-DPB1 alleles in Hellenic patients with early- and adult-onset MS (EOMS/AOMS), and possible associations with the HLA-DRB1*15:01 risk allele. Methods: One hundred MS-patients (28 EOMS, 72 AOMS) fulfilling the McDonald-2010 criteria were enrolled. HLA genotyping was performed with standard low-resolution Sequence-Specific Oligonucleotide techniques. Demographics, clinical and laboratory data were statistically processed using well-defined parametric and nonparametric methods and the SPSSv22.0 software. Results: No significant HLA-DPB1 differences were found between EOMS and AOMS patients for 23 distinct HLA-DPB1 and 12 HLA-DRB1 alleles. The HLA-DPB1*03 allele frequency was found to be significantly increased, and the HLA-DPB1*02 allele frequency significantly decreased, in AOMS patients compared to controls. The HLA-DPB1*04 allele was to be found significantly decreased in AOMS and EOMS patients compared to controls. Conclusions: Our study supports the previously reported risk susceptibility role of the HLA-DPB1*03 allele in AOMS among Caucasians. Additionally, we report for the first time a protective role of the HLA-DPB1*04 allele among Hellenic patients with both EOMS and AOMS.

Comprehensive meta-analysis reveals an association of the HLA-DRB1*1602 allele with autoimmune diseases mediated predominantly by autoantibodies

The human leukocytes antigen (HLA)-DRB1*16:02 allele has been suggested to be associated with many autoimmune diseases. However, a validation of the results of the different studies by a comprehensive analysis of the corresponding meta data is lacking. In this study, we performed a meta-analysis of the association between HLA-DRB1*16:02 allele with various autoimmune disorders. Our analysis shows that HLA-DRB1*16:02 allele was associated with systemic lupus erythematosus, anti-N-Methyl-d-Aspartate receptor (NMDAR) encephalitis, Graves' disease, myasthenia gravis, neuromyelitis optica and antibody-associated systemic vasculitis with microscopic polyangiitis (AASV-MPA). However, no such association was found for multiple sclerosis, autoimmune hepatitis type 1, rheumatoid arthritis, type 1 diabetes and Vogt-Koyanagi-Harada syndrome. Re-analysis of the studies after their categorization into autoantibody-dependent and T cell-dependent autoimmune diseases revealed that the HLA-DRB1*16:02 allele was strongly associated with disorder predominantly mediated by autoantibodies (OR = 1.93; 95% CI = 1.63-2.28, P = 1.95 × 10^-14) but not with those predominantly mediated by T cells (OR = 1.08; 95% CI = 0.87-1.34, P = .474). In addition, amino acid sequence alignment of common HLA-DRB1 subtypes demonstrated that HLA-DRB1*16:02 carries a unique motif of amino acid residues at position 67-74 which encodes the third hypervariable region. Taken together, the distinct pattern of disease association and the unique amino acid sequence of the third hypervariable region of the HLA-DRB1 provide some hints on how HLA-DRB1*16:02 is involved in the pathogenesis of autoimmune diseases.

Genetic Polymorphisms of rs3077 and rs9277535 in HLA-DP associated with Systemic lupus erythematosus in a Chinese population

Although the SLE risk gene loci of HLA-DR and HLA-DQ within the major histocompatibility complex (MHC) region has been gradually revealed by recent Genome-Wide Association studies (GWAS), the association of HLA-DP polymorphisms with SLE was minimally reported. Considering that the variants in rs3077 and rs9277535 in the HLA-DP region could influence the immune response by affecting antigen presentation of HLA class II molecules to CD4+ T cells, the present study aimed to explore the role of HLA-DP polymorphisms in SLE. In total, samples from 335 SLE patients and 635 healthy controls were collected and genotyped by a polymerase chain reaction-high resolution melting (PCR-HRM) assay. A significant positive correlation was observed between the SNP rs3077, rs9277535 of HLA-DP and SLE susceptibility (rs3077, OR = 0.74, 95%CI = 0.60-0.91, P = 0.004; rs9277535, OR = 0.72, 95%CI = 0.59-0.88, P = 0.001). Rs3077 polymorphism was corelated to IL-17, INF-γ and cutaneous vasculitis (P = 0.037, P = 0.020 and P = 0.006, respectively). Additionally, rs3077 AA genotype carriers showed lower concentration of inflammatory cytokines and lower cutaneous vasculitis incidence than did the other two genotype. No significant association was observed between rs9277535 and cytokines or any clinical features. In conclusion, HLA-DP polymorphisms (rs3077 and rs9277535) were associated with SLE susceptibility and the levels of some inflammatory cytokines in SLE patients.

The immunogenetics of multiple sclerosis. The frequency of HLA-alleles class 1 and 2 is lower in Southern Brazil than in the European population

ABSTRACT Objective To study the HLA of class 1and 2 in a multiple sclerosis (MS) population to verify the susceptibility for the disease in the Southern Brazil. Methods We analyzed patients with MS and controls, by direct sequencing of the genes related to HLA DRB1, DQB1, DPB1, A, B and C alleles with high resolution techniques. Results We found a lower frequency of all HLA alleles class 1 and 2 in MS and controls comparing to the European population. Several alleles had statistical correlation, but after Bonferroni correction, the only allele with significance was the HLA-DQB1*02:03, which has a positive association with MS. Conclusions Our data have different frequency of HLA-alleles than the previous published papers in the Southeast Brazil and European population, possible due to several ethnic backgrounds.

The immunogenetics of multiple sclerosis: A comprehensive review

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system and common cause of non-traumatic neurological disability in young adults. The likelihood for an individual to develop MS is strongly influenced by her or his ethnic background and family history of disease, suggesting that genetic susceptibility is a key determinant of risk. Over 100 loci have been firmly associated with susceptibility, whereas the main signal genome-wide maps to the class II region of the human leukocyte antigen (HLA) gene cluster and explains up to 10.5% of the genetic variance underlying risk. HLA-DRB1*15:01 has the strongest effect with an average odds ratio of 3.08. However, complex allelic hierarchical lineages, cis/trans haplotypic effects, and independent protective signals in the class I region of the locus have been described as well. Despite the remarkable molecular dissection of the HLA region in MS, further studies are needed to generate unifying models to account for the role of the MHC in disease pathogenesis. Driven by the discovery of combinatorial associations of Killer-cell Immunoglobulin-like Receptor (KIR) and HLA alleles with infectious, autoimmune diseases, transplantation outcome and pregnancy, multi-locus immunogenomic research is now thriving. Central to immunity and critically important for human health, KIR molecules and their HLA ligands are encoded by complex genetic systems with extraordinarily high levels of sequence and structural variation and complex expression patterns. However, studies to-date of KIR in MS have been few and limited to very low resolution genotyping. Application of modern sequencing methodologies coupled with state of the art bioinformatics and analytical approaches will permit us to fully appreciate the impact of HLA and KIR variation in MS.

Gender influence in EBV antibody response in multiple sclerosis patients from Kuwait

BACKGROUND

Epstein-Barr virus (EBV) infection is implicated with multiple sclerosis (MS) risk, exacerbation, and progression. The HLA-DRB1*1501 haplotype is a strong MS risk factor consistently documented in MS populations. There are no studies of EBV infections and HLA-DRB1*1501 haplotype associating with MS from Kuwait where MS prevalence has increased significantly.

OBJECTIVES

To determine the association of EBV infection with MS incidence, and to investigate HLA-DRB1*1501 as a potential genetic risk factor for MS in Kuwait.

METHODS

This is a case-control study involving 141 MS patients and 40 healthy controls. Antibody titers against EBV antigens' viral capsid antigen (VCA) and Epstein-Barr nuclear antigen 1 (EBNA1) were measured using enzyme-linked immunosorbent assays. HLA-DRB1*1501 haplotype assessment was done using rs3135005 TaqMan genotyping assay.

RESULTS

Antibody titers against EBV were significantly elevated in MS patients compared to healthy controls (anti-EBNA1, p=0.008; anti-VCA, p=0.028). MS males had higher antibody titers to EBNA1 than healthy male controls (p=0.005) and female MS patients (p=0.03). HLA-DRB1*1501 haplotype genotypes failed to generate a risk association with MS or EBV antibody titers (p=0.6).

CONCLUSION

An increased immune response to EBV infection is associated with MS incidence influenced by the type of antigen and sex. HLA-DRB1*1501 haplotype is not associated with MS risk in our Kuwaiti MS cohort.

HLA-DPB1 and HLA class I confer risk of and protection from narcolepsy

Type 1 narcolepsy, a disorder caused by a lack of hypocretin (orexin), is so strongly associated with human leukocyte antigen (HLA) class II HLA-DQA1(∗)01:02-DQB1(∗)06:02 (DQ0602) that very few non-DQ0602 cases have been reported. A known triggering factor for narcolepsy is pandemic 2009 influenza H1N1, suggesting autoimmunity triggered by upper-airway infections. Additional effects of other HLA-DQ alleles have been reported consistently across multiple ethnic groups. Using over 3,000 case and 10,000 control individuals of European and Chinese background, we examined the effects of other HLA loci. After careful matching of HLA-DR and HLA-DQ in case and control individuals, we found strong protective effects of HLA-DPA1(∗)01:03-DPB1(∗)04:02 (DP0402; odds ratio [OR] = 0.51 [0.38-0.67], p = 1.01 × 10(-6)) and HLA-DPA1(∗)01:03-DPB1(∗)04:01 (DP0401; OR = 0.61 [0.47-0.80], p = 2.07 × 10(-4)) and predisposing effects of HLA-DPB1(∗)05:01 in Asians (OR = 1.76 [1.34-2.31], p = 4.71 × 10(-05)). Similar effects were found by conditional analysis controlling for HLA-DR and HLA-DQ with DP0402 (OR = 0.45 [0.38-0.55] p = 8.99 × 10(-17)) and DP0501 (OR = 1.38 [1.18-1.61], p = 7.11 × 10(-5)). HLA-class-II-independent associations with HLA-A(∗)11:01 (OR = 1.32 [1.13-1.54], p = 4.92 × 10(-4)), HLA-B(∗)35:03 (OR = 1.96 [1.41-2.70], p = 5.14 × 10(-5)), and HLA-B(∗)51:01 (OR = 1.49 [1.25-1.78], p = 1.09 × 10(-5)) were also seen across ethnic groups in the HLA class I region. These effects might reflect modulation of autoimmunity or indirect effects of HLA class I and HLA-DP alleles on response to viral infections such as that of influenza.

The Role of HLA in MS Susceptibility and Phenotype

One of the most consistent findings in multiple sclerosis (MS) is that development of MS is linked with carriage of the class II human leucocyte antigen (HLA) molecule HLA-DRB1*15:01; around 60 % of Caucasian MS patients carry this allele compared to 25-30 % of ethnically matched healthy individuals. However, other HLA molecules have also been linked to the development of MS. In this chapter, the association between different HLA types and susceptibility to MS will be reviewed, and other linkages between the carriage of specific HLA molecules and clinical and experimental findings in MS will be considered.

Myelin oligodendrocyte glycoprotein induces aquaporin-4 autoantibodies in mouse experimental autoimmune encephalomyelitis

To investigate whether AQP4 autoantibodies (AQP4-Ab) are causative for neuromyelitis optica (NMO), the production of AQP4-Ab and clinical experimental autoimmune encephalomyelitis (EAE) was investigated in mice administered with mouse AQP4 antigen or myelin oligodendrocyte glycoprotein (MOG35-55) alone, and in combination. Eight- to twelve-week-old female C57BL/6 mice were randomly immunized with encephalitogenic mixture containing 300 μg of MOG35-55 or AQP4 antigen alone, and in combination in complete Freund's adjuvant supplemented with H37Ra M. tuberculosis. The incidence of EAE, Weaver 15 scores, and body weight was evaluated. ELISA was used to detect serum mouse AQP4-Ab. Mice injected with MOG35-55 and MOG33-35 plus AQP4 antigen began to show EAE symptoms 12 days after immunization. The incidence of EAE was 91.6%, and 62.5%, for MOG35-55 alone and MOG33-35 plus AQP4 antigen groups, respectively, while AQP4 antigen alone didn't develop EAE. In all but the control group, serum AQP4-Ab levels were increased, and correlated positively with Weaver 15 score (rs=0.713, p=0.000) and negatively with body weight changes (rs=-0.415, p=0.011). Injection of human NMO sera positive for AQP4-Ab exacerbated MOG-induced EAE. Our results suggest that AQP4-Ab can be produced in MOG-induced MS model, and itself is not sufficient for the development of EAE, implying that NMO might be a subtype or transition from MS.

Classical HLA-DRB1 and DPB1 alleles account for HLA associations with primary biliary cirrhosis

Susceptibility to primary biliary cirrhosis (PBC) is strongly associated with HLA region polymorphisms. To determine if associations can be explained by classical HLA determinants we studied Italian 676 cases and 1440 controls with genotyped with dense single nucleotide polymorphisms (SNPs) for which classical HLA alleles and amino acids were imputed. Although previous genome-wide association studies and our results show stronger SNP associations near DQB1, we demonstrate that the HLA signals can be attributed to classical DRB1 and DPB1 genes. Strong support for the predominant role of DRB1 is provided by our conditional analyses. We also demonstrate an independent association of DPB1. Specific HLA-DRB1 genes (*08, *11 and *14) account for most of the DRB1 association signal. Consistent with previous studies, DRB1*08 (p = 1.59 × 10⁻¹¹) was the strongest predisposing allele where as DRB1*11 (p = 1.42 × 10⁻¹⁰) was protective. Additionally DRB1*14 and the DPB1 association (DPB1*03:01) (p = 9.18 × 10⁻⁷) were predisposing risk alleles. No signal was observed in the HLA class 1 or class 3 regions. These findings better define the association of PBC with HLA and specifically support the role of classical HLA-DRB1 and DPB1 genes and alleles in susceptibility to PBC.

Transancestral mapping of the MHC region in systemic lupus erythematosus identifies new independent and interacting loci at MSH5, HLA-DPB1 and HLA-G

Objectives

Systemic lupus erythematosus (SLE) is a chronic multisystem genetically complex autoimmune disease characterised by the production of autoantibodies to nuclear and cellular antigens, tissue inflammation and organ damage. Genome-wide association studies have shown that variants within the major histocompatibility complex (MHC) region on chromosome 6 confer the greatest genetic risk for SLE in European and Chinese populations. However, the causal variants remain elusive due to tight linkage disequilibrium across disease-associated MHC haplotypes, the highly polymorphic nature of many MHC genes and the heterogeneity of the SLE phenotype.

Methods

A high-density case-control single nucleotide polymorphism (SNP) study of the MHC region was undertaken in SLE cohorts of Spanish and Filipino ancestry using a custom Illumina chip in order to fine-map association signals in these haplotypically diverse populations. In addition, comparative analyses were performed between these two datasets and a northern European UK SLE cohort. A total of 1433 cases and 1458 matched controls were examined.

Results

Using this transancestral SNP mapping approach, novel independent loci were identified within the MHC region in UK, Spanish and Filipino patients with SLE with some evidence of interaction. These loci include HLA-DPB1, HLA-G and MSH5 which are independent of each other and HLA-DRB1 alleles. Furthermore, the established SLE-associated HLA-DRB1*15 signal was refined to an interval encompassing HLA-DRB1 and HLA-DQA1. Increased frequencies of MHC region risk alleles and haplotypes were found in the Filipino population compared with Europeans, suggesting that the greater disease burden in non-European SLE may be due in part to this phenomenon.

Conclusion

These data highlight the usefulness of mapping disease susceptibility loci using a transancestral approach, particularly in a region as complex as the MHC, and offer a springboard for further fine-mapping, resequencing and transcriptomic analysis.

Relationship between HLA-DRB1 polymorphism and susceptibility or resistance to multiple sclerosis in Caucasians: a meta-analysis of non-family-based studies

OBJECTIVE

To identify the contribution of HLA-DRB1 alleles to susceptibility or resistance to multiple sclerosis (MS) in Caucasians through a meta-analysis of non-family-based studies.

METHODS

A systematic review of case-control studies in Caucasians was performed. Studies examining allele or phenotype frequencies were analyzed separately. Odds ratio (OR) and 95% confidence intervals (CIs) were used. We also used the relatively predispositional effect (RPE) method to analyze several allele frequency studies to avoid skewed results due to some strongly associated alleles.

RESULTS

A total of 5464 cases and 7809 controls from 14 allele frequency studies and a total of 5401 cases and 7538 controls from 23 phenotype frequency studies were analyzed. DRB1*15 was definitely the strongest risk factor for MS (allele group, Pc<0.00013, OR 2.59, 95%CI 2.34-2.87; phenotype group, Pc<0.00013, OR 3.35, 95%CI 2.95-3.80). DRB1*03 frequencies were significantly increased among MS cases in the phenotype group (Pc= 0.0013, OR 1.21, 95%CI 1.09-1.33) but not in the allele group. DRB1*14 and DRB1*07 showed protective effects against MS in both groups (DRB1*14, allele group, Pc<0.00013, OR 0.53, 95%CI 0.42-0.66; phenotype group, Pc<0.00013, OR 0.57, 95%CI 0.45-0.71; DRB1*07, allele group, Pc<0.0026, OR 0.75, 95%CI 0.64-0.87; phenotype group, Pc<0.00013, OR 0.67, 95%CI 0.61-0.73). By RPE method, DRB1*14, and DRB1*07 showed protective effects after excluding DRB1*15 from the analysis. DRB1*03 was significantly higher in MS cases than controls after removing both DRB1*15 and DRB1*14.

CONCLUSIONS

In Caucasians, we highlighted the definite protective role of HLA-DRB1*14 and DRB1*07 for MS. DRB1*03 is probably the only risk factor for MS besides DRB1*15 and a common genetic foundation for autoimmune disease. Targeting to these alleles may have potential values in prevention or therapy for MS in the specific population.

HLA-DR allele polymorphism and multiple sclerosis in Chinese populations: a meta-analysis

BACKGROUND

The association of human leukocyte antigen (HLA) genes and multiple sclerosis (MS) has been extensively investigated in Caucasians, but less so in Oriental races such as Chinese.

OBJECTIVES

To review studies on association of HLA class II alleles with MS in the Chinese population.

METHODS

An extensive search for published studies up to June 2010 was performed in the electronic databases. The meta-analysis facilities in the NCSS statistical package were utilized to analyze the findings in these studies. The odds ratios (ORs) of HLA-DR allele distributions in MS were analyzed against controls.

RESULTS

Eleven case-control studies were identified: nine genotyping and two serotyping studies. Six genotyping studies were suitable for HLA-DRB1 allele meta-analysis, which showed that HLA-DRB1*15 was associated with risk of MS in the combined group (308 cases and 407 controls; OR 1.39) while the HLA-DRB1*09 and HLA-DRB1*0901 alleles were protective. When the equivalent serotypes in these six studies were combined with the results from the two serotyping studies (431 cases and 652 controls) for a meta-analysis of HLA-DR serotypes, HLA-DR2 was a risk factor (OR 1.63) and HLA-DR9 was strongly protective in the combined group (OR 0.64).

CONCLUSIONS

Although limited data are available, our meta-analysis suggests that HLA-DR2/DRB1*15 are also associated with risk of MS in the Chinese population but less strongly so than in Western MS populations, whereas HLA-DR9 alleles appear to confer resistance in this population.

HLA-DPB1 0501 is associated with susceptibility to anti-aquaporin-4 antibodies positive neuromyelitis optica in southern Han Chinese

OBJECTIVES

To analyze the role of HLA-DRB1 and -DPB1 alleles in the pathogenesis of neuromyelitis optica (NMO) and multiple sclerosis in Southern Han Chinese.

METHODS

Thirty serum anti-aquaporin 4 antibodies (AQP4-Ab)-positive NMO patients, 53 conventional multiple sclerosis (C-MS) patients, and 93 controls (CTLs) were enrolled. The HLA-DRB1 and -DPB1 alleles of the subjects were determined by sequencing-based typing (SBT).

RESULTS

The frequency of the DRB1 0901 was lower in NMO patients than in CTLs (P(uncorr)=0.022, OR: 0.194, 95% CI: 0.043-0.876), and DRB1 1602 was higher in NMO patients than in C-MS (P(uncorr)=0.038, OR: 3.491, 95% CI: 1.024-11.896) and CTLs (P(uncorr)=0.051, OR: 2.711, 95% CI: 0.971-7.556). The frequency of DPB1 0501 was significant higher in NMO patients than in C-MS (P(uncorr)=0.018, OR: 4.629, 95% CI: 1.235-17.350) and CTLs (P(uncorr)=0.001, P(corr)=0.022, OR: 7.096, 95% CI: 2.011-25.044).

CONCLUSIONS

DPB1 0501 correlates with risk of AQP4-Ab positive NMO in Southern Han Chinese.

A polymorphism in the HLA-DPB1 gene is associated with susceptibility to multiple sclerosis

We conducted an association study across the human leukocyte antigen (HLA) complex to identify loci associated with multiple sclerosis (MS). Comparing 1927 SNPs in 1618 MS cases and 3413 controls of European ancestry, we identified seven SNPs that were independently associated with MS conditional on the others (each P ≤ 4 x 10(-6)). All associations were significant in an independent replication cohort of 2212 cases and 2251 controls (P ≤ 0.001) and were highly significant in the combined dataset (P ≤ 6 x 10(-8)). The associated SNPs included proxies for HLA-DRB1*15:01 and HLA-DRB1*03:01, and SNPs in moderate linkage disequilibrium (LD) with HLA-A*02:01, HLA-DRB1*04:01 and HLA-DRB1*13:03. We also found a strong association with rs9277535 in the class II gene HLA-DPB1 (discovery set P = 9 x 10(-9), replication set P = 7 x 10(-4), combined P = 2 x 10(-10)). HLA-DPB1 is located centromeric of the more commonly typed class II genes HLA-DRB1, -DQA1 and -DQB1. It is separated from these genes by a recombination hotspot, and the association is not affected by conditioning on genotypes at DRB1, DQA1 and DQB1. Hence rs9277535 represents an independent MS-susceptibility locus of genome-wide significance. It is correlated with the HLA-DPB1*03:01 allele, which has been implicated previously in MS in smaller studies. Further genotyping in large datasets is required to confirm and resolve this association.

Refining the association of MHC with multiple sclerosis in African Americans

Multiple sclerosis (MS) is a common demyelinating disease of the central nervous system mediated by autoimmune and neurodegenerative pathogenic mechanisms. Multiple genes account for its moderate heritability, but the only genetic region shown to have a large replicable effect on MS susceptibility is the major histocompatibility complex (MHC). Strong linkage disequilibrium (LD) across the MHC has made it difficult to fully characterize individual genetic contributions of this region to MS risk in previous studies. African Americans are at a lower risk for MS when compared with northern Europeans and Americans of European descent, but greater haplotypic diversity and distinct patterns of LD suggest that this population may be particularly informative for fine-mapping efforts. To examine the role of the MHC in African American MS, a case-control association study was performed with 499 African American MS patients and 750 African American controls that were genotyped for 6040 MHC region single nucleotide polymorphisms (SNPs). A replication data set consisting of 451 African American patients and 718 African American controls was genotyped for selected SNPs. Two MHC class II SNPs, rs2647040 and rs3135021, were significant in the replication cohort and partially tagged DRB1*15 alleles. Surprisingly, in comparison to similar studies of individuals of European descent, the MHC seems to play a smaller role in MS susceptibility in African Americans, consistent with pervasive genetic heterogeneity across ancestral groups, and may explain the difference in MS susceptibility between African Americans and individuals of European descent.

Prostaglandins in pathogenesis and treatment of multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS) characterized by inflammation, demyelination, axonal loss, and gliosis. The inflammatory lesions are manifested by a large infiltration and a heterogeneous population of cellular and soluble mediators of the immune system, such as T cells, B cells, macrophages, and microglia, as well as a broad range of cytokines, chemokines, antibodies, complement, and other toxic substances. Prostaglandins (PGs) are arachidonic acid-derived autacoids that have a role in the modulation of many physiological systems including the CNS, respiratory, cardiovascular, gastrointestinal, genitourinary, endocrine, and immune systems. PG production is associated with inflammation, a major feature in MS that is characterized by the loss of myelinating oligodendrocytes in the CNS. With respect to the role of PGs in the induction of inflammation, they can be effective mediators in the pathophysiology of MS. Thus use of agonists or antagonists of PG receptors may be considered as a new therapeutic protocol in MS. In this review, we try to clarify the role of PGs in immunopathology and treatment of MS.