HLA-DP antigens and HTLV-1 antibody status among Japanese with multiple sclerosis: evidence for an increased frequency of HLA-DPw4

Development of a humanized HLA-A2.1/DP4 transgenic mouse model and the use of this model to map HLA-DP4-restricted epitopes of HBV envelope protein

A new homozygous humanized transgenic mouse strain, HLA-A2.1(+/+)HLA-DP4(+/+) hCD4(+/+)mCD4(-/-)IAβ(-/-)β2m(-/-) (HLA-A2/DP4), was obtained by crossing the previously characterized HLA-A2(+/+)β2m(-/-) (A2) mouse and our previously created HLA-DP4(+/+) hCD4(+/+)mCD4(-/-)IAβ(-/-) (DP4) mouse. We confirmed that the transgenes (HLA-A2, HLA-DP4, hCD4) inherited from the parental A2 and DP4 mice are functional in the HLA-A2/DP4 mice. After immunizing HLA-A2/DP4 mice with a hepatitis B DNA vaccine, hepatitis B virus-specific antibodies, HLA-A2-restricted and HLA-DP4-restricted responses were observed to be similar to those in naturally infected humans. Therefore, the present study demonstrated that HLA-A2/DP4 transgenic mice can faithfully mimic human cellular responses. Furthermore, we reported four new HLA-DP4-restricted epitopes derived from HBsAg that were identified in both vaccinated HLA-A2/DP4 mice and HLA-DP4-positive human individuals. The HLA-A2/DP4 mouse model is a promising preclinical animal model carrying alleles present to more than a quarter of the human population. This model should facilitate the identification of novel HLA-A2- and HLA-DP4-restricted epitopes and vaccine development as well as the characterization of HLA-DP4-restricted responses against infection in humans.

Peptide-based molecular analyses of HLA class II-associated susceptibility to autoimmune diseases

Recent advances in knowledge of crystal structures of MHC class II molecules has advanced understanding of the molecular basis for interactions between peptides and HLA class II molecules. Polymorphism of HLA class II molecules influences structures of peptides bound to HLA class II molecules. To better understand mechanisms related to particular HLA class II alleles and autoimmune diseases, it is important to identify self-peptides presented by disease-susceptible HLA class II molecules and triggering disease-causative autoreactive T cells. Autoimmune diseases occur in Caucasians, Blacks and Asians, albeit with a different incidence. In some autoimmune diseases, disease-susceptible HLA class II alleles are closely related but different, and clinical manifestations of diseases differ among ethnic groups. These phenomena strongly suggest that difference in autoimmune self-peptide(s) in the context of disease-susceptible HLA class II molecules may explain the different clinical manifestations of diseases. Therefore, a comparison among disease-susceptible HLA class II alleles, autoimmune self-peptides and clinical manifestations of autoimmune diseases in different ethnic groups would be instructive. We directed efforts to determining: (1) HLA-class II alleles specific to Asian populations and which are associated with susceptibility to autoimmune diseases, (2) binding-peptide motifs for these HLA class II molecules, and (3) self-peptides presented by susceptible HLA class II molecules to stimulate autoreactive T cells related to the development of autoimmune diseases in Asians. In this review, our related recent investigations are described and the uniqueness of HLA class II-associated autoimmune diseases in Asians is given emphasis.

Molecular analyses of HLA class II-associated susceptibility to subtypes of autoimmune diseases unique to Asians

It is well known that individuals positive for particular HLA-class II alleles show high risks for the development of Takayasu arteritis and other diseases caused by immunological disorders such as autoimmune diseases and allergies. HLA class II molecules present antigenic peptides to CD4+ T cells. Their extensive polymorphism affects the structures of peptides bound to HLA class II molecules to create individual differences in immune responses to antigenic peptides. To better understand the mechanisms for association between HLA class II alleles and susceptibility to autoimmune diseases, it is important to identify self-peptides presented by disease-susceptible HLA class II molecules and triggering disease-causative T cells. Many autoimmune diseases are observed in all ethnic groups, whereas the incidences of diseases, clinical manifestations and disease-susceptible HLA class II alleles are different among various ethnic groups for some autoimmune diseases. These phenomena suggest that differences in autoimmune self-peptide(s) in the context of disease-susceptible HLA class II molecules may cause these differences. Therefore, comparisons among disease-susceptible HLA class II alleles, autoimmune self-peptides and clinical manifestations of autoimmune diseases in different ethnic groups would be helpful in determining the pathogenesis of the diseases. In this paper, we describe our recent findings on: (1) the uniqueness of both clinical manifestations and HLA-linked genetic background of Asian-type (optico-spinal form) multiple sclerosis; (2) the structural characteristics of peptides bound to HLA-DQ molecules susceptible to insulin-dependent diabetes mellitus; (3) the identification of a disease-related autoantigenic peptide presented by disease-susceptible HLA-DQ molecules in Asians-specific infant onset myasthenia gravis; and (4) a manipulation of human T cell response by altered peptide ligands, as a possible candidate for new and antigen-specific immuno-suppressive therapy against autoimmune diseases.

HLA-DP-associated susceptibility to the optico-spinal form of multiple sclerosis in the Japanese

We studied polymorphism of the HLA-DP gene in 46 patients with optico-spinal form (Asian type) multiple sclerosis (MS) showing recurrent opticomyelitis and 46 patients with Western type MS with disseminated central nervous system involvement. We previously reported a significant association between an HLA-DRB1 *1501-DRB5*0101 haplotype and susceptibility to Western type but not Asian type MS. In the present study, we found that the frequencies of DPA1 *0202 and DPB1 *0501 alleles were significantly increased in patients with Asian type MS, as compared with findings in 92 healthy control subjects (91.3% vs 65.2%, P(corr)<0.05 and 89.1% vs 63.0%, P(corr)<0.05 respectively), but not in Western type MS. Our data provide further evidence that Asian and Western type MS are distinct regarding the immunogenetic background.

Identification of multiple sclerosis-associated genes

Multiple sclerosis (MS) is a complex genetic trait. Analyses to identify genetic variants that increase susceptibility to MS have primarily focused on candidate genes, either in family linkage investigations or in association (linkage disequilibrium) studies in sporadic cases and control subjects. Most of the candidate genes considered to date either influence immune function or encode structural myelin proteins. Recently, three preliminary whole genomic surveys were completed, and they reveal multiple loci of possible genetic linkage that are worthy of further study. No convincing evidence for a single strong locus has emerged from analysis of the three studies. Linkage promises to focus the future choice of candidate genes for further investigation.

Western versus Asian types of multiple sclerosis: immunogenetically and clinically distinct disorders

The polymorphism of HLA-DRB1, -DRB3, and -DRB5 genes as well as magnetic resonance images of the brain and spinal cord were studied in 57 Japanese patients with multiple sclerosis (MS). Twenty-three patients clinically displayed selective involvement of the optic nerve and spinal cord and were classified as having Asian-type MS. The other 34 patients had disseminated central nervous system involvement and were classified as having Western-type MS. Patients with Asian-type MS had fewer brain lesions shown by magnetic resonance imaging, but more gadolinium-enhanced spinal cord lesions than did patients with Western-type MS (47% vs 17%). Furthermore, the DR2-associated DRB1*1501 allele and DRB5*0101 allele were associated with Western-type MS (41.2%), but not with either Asian-type MS (0%) or healthy control subjects (14.2%). Heterogeneity in the immunogenetic background and in the magnetic resonance imaging features between the two subtypes of MS thus suggests the presence of two etiologically distinct diseases in Asians.

Absence of strong HLA-DR/DQ-DP linkage disequilibrium in the British and French Canadian Caucasoid populations

HLA-DR/DQ-DP linkage disequilibrium was investigated in healthy, unrelated British (n = 150) and French Canadian (n = 67) Caucasoid subjects. HLA-DR and DQ typing was performed by Taq I DNA-RFLP analysis, while DPB1 typing was performed by PCR-SSOP. chi 2 and Fisher's exact tests were performed for all 2-locus biallelic comparisons and coefficients of linkage disequilibrium determined. In the British population, only one example of linkage disequilibrium, significant at P = 0.05 (after correction for the number of comparisons made) was seen (DPB1*0101-DRB1*0301[17(1)]). Additional associations, significant at P = 0.05 before correction for the number of comparisons were also seen, including DPB1*0401-DRB1*15, DPB1*1101-DRB1*0701(7(1)), DPB1*1701-DRB1*0701/ 2(7(2)), DPB1*0101-DQA1*0501, DPB1*0401-DQA1*0102, DPB1*0501-DQA1*0102, DPB1*0101-DQB1*0201, DPB1*0401-DQB1*0602/0603 and DPB1*1101-DQB1*0201. With one exception (DPB1*1101-DQB1*0201), none of these associations was seen in the French Canadian group. These results indicate that although more frequent than thought hitherto, HLA class II linkage disequilibrium involving DPB1 alleles is generally weak, and can differ even between different caucasoid populations. This may have implications for HLA and disease studies.

Frequency of HLA-DPB1 alleles in multiple sclerosis patients from Northern Ireland

Using sequence-specific oligonucleotide probes, no altered distribution in the frequency of HLA-DPB1 alleles was found in multiple sclerosis patients from Northern Ireland. Although present in the controls, linkage disequilibrium between HLA-DPB1*0101 and HLA-DR17 was not found in multiple sclerosis patients.

HLAs and genes in Japanese patients with multiple sclerosis: evidence for increased frequencies of HLA-Cw3, HLA-DR2, and HLA-DQB1*0602

The distribution of HLA-A, B, C, DR and DRB1, DQB1, DPB1 alleles was studied in 60 Japanese patients with clinically definite multiple sclerosis (MS) using serologic and genomic analysis. We found significant associations with HLA-Cw3 (p = 0.002, pc = 0.012, RR = 3.2), DR2 (p = 0.007, RR = 2.6), and DQB1*0602 (p = 0.04, RR = 4.0) in Japanese patients for the first time. The combined presence of Cw3 and DR2 gave a higher risk than each antigen alone. The reported increase in the frequency of DPw4 in Japanese MS patients [12] could not be confirmed by our genomic study. The frequencies of all of the residues in each variable region of the amino acid sequences of DQ beta and DP beta chains were not different between the MS patients and the controls. These results suggest that MS susceptibility may result from polygenic influences and from the presence of environmental factors.

Novel HLA-DR2-related haplotypes in Hong Kong Chinese implicate the DQB1*0602 allele in susceptibility to multiple sclerosis

Multiple sclerosis (MS) is strongly associated with the HLA-Dw2 haplotype DRw15.DQw6 in Caucasoids, although the relative contributions of DR and DQ loci to disease susceptibility are unknown. The situation is further complicated by the apparent lack of an association between DR2 and MS in Orientals. This study examined 42 DR2-positive chromosomes in healthy Chinese and 12 DR2-positive chromosomes in MS patients from Hong Kong, using oligonucleotide hybridizations of DQA1, DQB1, DRB1, and DRB5 polymerase chain reaction (PCR) products. There was marked heterogeneity in DR2-related haplotypes in controls (ten types), where the most frequent haplotype, confirmed in one family, involved the novel arrangement DRB1*1501, DQB1*0601. Another common haplotype had the unusual combination of DRB1*1602, DRB5*0101 as confirmed by DNA sequencing of the DRB5 allele. In contrast, the most common DR2-related haplotype in MS patients was the 'classical' Dw2 haplotype DRB1*1501, DQB1*0602, with a frequency of 50% compared with 12% in controls (P = 0.01). Novel DR,DQ linkage disequilibrium relationship in Hong Kong Chinese have permitted recognition of DQB1*0602 as a susceptibility allele in DR2-positive MS patients, although a role for the DRB1*1501 allele in MS pathogenesis has not been excluded by this study.

HLA-DPB1 gene polymorphism and multiple sclerosis: a large case-control study in the southwest of France

The polymorphism at the HLA-DPB1 locus has been characterized in a large number of patients with multiple sclerosis (n = 112) and in healthy controls (n = 115). Both patients and controls lived in the southwest of France (in the Pyrénées Atlantiques) and had similar ethnic background. The typing procedure involved the selective amplification of the second exon of the DPB1 locus by polymerase chain reaction, followed by hybridization of the amplified DNA with 14 sequence-specific oligonucleotide probes. Individual alleles were identified by the pattern of hybridization of the different probes. The distribution of the DPB1 alleles was not significantly different in multiple sclerosis patients and controls (p = 0.11). This does not corroborate the reported association of multiple sclerosis with the primed lymphocyte typing (PLT)-defined DPw4 specificity and is not in favour of a role played by polymorphic residues of the DP molecule in susceptibility to multiple sclerosis.

HLA class II-associated genetic susceptibility in multiple sclerosis: a critical evaluation

Multiple sclerosis (MS) has, since the 1970s, been known to be associated with the HLA-Dw2 and -DR2 specificities in Caucasian Europeans and North Americans. By the use of genomic typing techniques, the association has been specified to be with the DRw15,DQw6,Dw2, i.e. the DRB1*1501-DQA1*0102-DQB1*0602 haplotype. A significant DPw4 association in Scandinavian MS patients has been described in one report. However, this association has not been confirmed in several subsequent studies with patients from the same and other ethnic groups. During the last few years several reports, based on serological, RFLP and PCR-SSO data, have suggested that the HLA class II-associated MS susceptibility gene(s) may be more closely associated with the DQ than with the DR subregion. The observations that the HLA-DQB1 genes of MS patients share long stretches of sequence motifs and also carry DQA1 alleles encoding glutamine at position 34 of the DQ alpha chain have received considerable attention. It has been suggested that the susceptibility to develop MS might be determined by the corresponding DQ alpha-beta heterodimers either encoded in cis or in trans. We have investigated these issues in a large group of Swedish MS patients (n = 179). We found that the associations with the suggested DQB1 sequences and position 34 of the DQ alpha chain were due to linkage disequilibrium and secondary to the association with the DRw15,DQw6,Dw2 haplotype (p less than 10(-9) and p less than 10(-8), respectively). No overrepresentation of the implicated DQ alpha-beta heterodimers was observed in DRw15,DQw6,Dw2-negative patients.(ABSTRACT TRUNCATED AT 250 WORDS)

No association between susceptibility to multiple sclerosis and HLA-DPB1 alleles in the French Canadian population

HLA-DPB1 typing was performed using polymerase chain reaction DNA amplification and sequence-specific oligonucleotide probing (PCR-SSOP) which permitted identification of 17 distinct DPB alleles using 15 oligonucleotide probes. The accuracy of this approach was confirmed in an initial study of 26 human B-lymphoblastoid cell lines which demonstrated close agreement between PCR-SSOP and PLT assigned types. A cohort of 47 adult French Canadians was then studied to provide an estimate of DPB1 allelic frequencies in an ethnically homogeneous population. DPB1*0401 was the most frequent phenotype (61.5%) and only DPB1*0101, 0301 and 0402 were also present at frequencies greater than 10%. HLA-DPw4 has been reported to be associated with multiple sclerosis (MS) but our PCR-SSOP analysis of 52 French Canadian MS patients showed no association with either the DPB1*0401 or DPB1*0402 splits of DPw4 or with any other DPB1 allele.