MHC Haplotype Research Articles

Can Genetics Risk-Stratify Patients with Membranous Nephropathy?

Can Genetics Risk-Stratify Patients with Membranous Nephropathy?

AB0586 Role of particular class i mhc genotypes and haplotypes in determining different traits within the psoriatic arthritis phenotypes

BackgroundA rigorously ascertained psoriatic arthritis (PsA) cohort demonstrated considerable genetic heterogeneity and provided preliminary evidence that MHC genes determine quantitative traits within the PsA phenotype with different patterns of MHC...

The peptide motif of the single dominantly expressed class I molecule of the chicken MHC can explain the response to a molecular defined vaccine of infectious bursal disease virus (IBDV)

In contrast to typical mammals, the chicken MHC (the BF-BL region of the B locus) has strong genetic associations with resistance and susceptibility to infectious pathogens as well as responses to vaccines. We have shown that the chicken MHC encodes a single dominantly expressed class I molecule whose peptide-binding motifs can determine resistance to viral pathogens, such as Rous sarcoma virus and Marek’s disease virus. In this report, we examine the response to a molecular defined vaccine, fp-IBD1, which consists of a fowlpox virus vector carrying the VP2 gene of infectious bursal disease virus (IBDV) fused with β-galactosidase. We vaccinated parental lines and two backcross families with fp-IBD1, challenged with the virulent IBDV strain F52/70, and measured damage to the bursa. We found that the MHC haplotype B15 from line 15I confers no protection, whereas B2 from line 61 and B12 from line C determine protection, although another locus from line 61 was also important. Using our peptide motifs, we found that many more peptides from VP2 were predicted to bind to the dominantly expressed class I molecule BF2*1201 than BF2*1501. Moreover, most of the peptides predicted to bind BF2*1201 did in fact bind, while none bound BF2*1501. Using peptide vaccination, we identified one B12 peptide that conferred protection to challenge, as assessed by bursal damage and viremia. Thus, we show the strong genetic association of the chicken MHC to a T cell vaccine can be explained by peptide presentation by the single dominantly expressed class I molecule.

Differential RNA expression of TLR pathway signaling pathways in macrophages from chickens stimulated with Interferon γ in disease resistant B2 haplotypes versus susceptible B19 haplotypes. (P1216)

Abstract MHC has been associated with immunity in several species and studies have demonstrated association of MHC B haplotype in chickens and resistance to a variety of viral pathogens including Marek’s disease virus, avian leucosis virus, Newcastle disease virus and Rous sarcoma virus. Previous studies in our laboratory have shown that chicks with the homozygous B2 MHC haplotypes are more resistant to respiratory illness following avian coronavirus infection, than homozygous B19 chicks. Further studies demonstrated more vigorous responses of B2 macrophages to Poly I:C and IFNγ stimulation than responses of B19 derived macrophages. Macrophages play a critical role in the early innate response and mobilization of the adaptive immune responses. Next Generation Sequencing of IFNγ stimulated macrophages show differential expression of genes of the toll-like receptor signaling pathway. Macrophages were stimulated for 0, 1, 2, 4, 8, 16, 24 and 48 hours. At most time points more genes were stimulated in macrophages of the disease resistant B2 haplotype and quantification of RNA expression (fold-increase) indicates earlier and more robust stimulation of several genes.

Characterization and specification of microsatellite markers in the HLA-DRB1 gene region: A revision to major histocompatibility complex database

Association between HLA-DRB1 and a large number of diseases such as multiple sclerosis, type I diabetes and rheumatoid arthritis has been demonstrated. In the present study, we attempted to identify and characterize potential microsatellites in the HLA-DRB1 gene region to find specific markers for genotyping and linkage analysis of this gene. The microsatellites including M2_3_22, M2_2_36, D6S2878, D6S2805, D6S2879 and D6S2880 were selected from microsatellite resource in the Major Histocompatibility Complex database (dbMHC). In silico analysis showed that only M2_3_22 was specific for HLA-DRB1. Moreover, our findings revealed some more accurate characteristics of the other investigated microsatellites. M2_3_22 existed as a single copy in all the MHC haplotype sequences and was located next to HLA-DRB1. Therefore, a new set of primers compatible with all the last published MHC haplotype sequences were designed and used to amplify M2_3_22 in 164 DNA samples obtained from unrelated Iranian individuals. M2_3_22 was successfully amplified in all DNA samples and three different alleles were identified. This locus was found in the Hardy-Weinberg equilibrium (P>0.05) in the studied population. Together, the findings suggested that M2_3_22 could be introduced as a specific locus in the HLA-DRB1 gene region for linkage analysis and disease association studies.

Barrett associated MHC and FOXF1 variants also increase esophageal carcinoma risk

Barrett's esophagus, with gastroesophageal reflux disease and obesity as risk factors, predisposes to esophageal adenocarcinoma (EAC). Recently a British genome wide association study identified two Barrett's esophagus susceptibility loci mapping within the major histocompatibility complex (MHC; rs9257809) and closely to the Forkhead-F1 (FOXF1; rs9936833) coding gene. An interesting issue is whether polymorphisms associated with Barrett's esophagus, are also implicated in esophageal carcinoma (EC), and more specifically EAC genesis. Assessing the individual genetic susceptibility can help identify high risk patients more prone to benefit from surveillance programs. Our hypothesis: Barrett associated MHC and FOXF1 variants modify EC risk in Caucasians. In a Dutch case-control study, 431 patients with EC and 605 healthy controls were included. Polymorphisms at chromosomes 6p21 (MHC) and 16q24 (FOXF1) were determined by means of real-time polymerase chain reaction (RT-PCR). Logistic regression analysis was used to calculate odds ratios with 95% confidence intervals. The FOXF1 rs9936833 variant C allele was associated with an increased EAC susceptibility; OR, [95% CI]; 1.21, [0.99-1.47]. A sex-stratified analysis revealed a similar association in males; 1.24 [1.00-1.55]. The variant MHC rs9257809 G allele as well as the MHC heterozygous AG genotype significantly increased ESCC risk; 1.76 [1.16-2.66] and 1.74 [1.08-2.80], respectively. Sex-stratification showed that the variant G allele was especially present in female patients; 2.32 [1.04-5.20]. In conclusion, this study provides evidence that MHC rs9257809 and FOXF1 rs9936833 variants, associated with Barrett's esophagus, also increase ESCC and EAC susceptibility in Caucasians. FOX proteins are transcription factors involved in organogenesis of the GI tract, while MHC haplotypes are strongly associated with smoking behavior, a crucial risk factor for ESCC. Assessing the individual genetic susceptibility can help identify high risk patients more prone to benefit from (Barrett) surveillance programs.

Unusual selection and peripheral homeostasis for immunoregulatory CD4− CD8−T cells

Immunoregulatory CD4(-) CD8(-) (double-negative; DN) T cells exhibit a unique antigen-specific mode of suppression, yet the ontogeny of DN T cells remains enigmatic. We have recently shown that 3A9 T-cell receptor (TCR) transgenic mice bear a high proportion of immunoregulatory 3A9 DN T cells, facilitating their study. The 3A9 TCR is positively selected on the H2(k) MHC haplotype, is negatively selected in mice bearing the cognate antigen, namely hen egg lysozyme, and there is absence of positive selection on the H2(b) MHC haplotype. Herein, we take advantage of this well-defined 3A9 TCR transgenic model to assess the thymic differentiation of DN T cells and its impact on determining the proportion of these cells in secondary lymphoid organs. We find that the proportion of DN T cells in the thymus is not dictated by the nature of the MHC-selecting haplotype. By defining DN T-cell differentiation in 3A9 TCR transgenic CD47-deficient mice as well as in mice bearing the NOD.H2(k) genetic background, we further demonstrate that the proportion of 3A9 DN T cells in the spleen is independent of the MHC selecting haplotype. Together, our findings suggest that immunoregulatory DN T cells are subject to rules distinct from those imposed upon CD4 T cells.

LEI0258 Microsatellite Variability in Khorasan, Marandi, and Arian Chickens

Microsatellite LEI0258 is a genetic marker for chicken MHC haplotypes and can be used as an indicator of the influence of population genetics on immune responses. LEI0258 microsatellite variability in three Iranian indigenous chicken populations (Khorasan, Marandi, and Arian) was investigated. In total, 142 Khorasan, 42 Marandi, and 58 Arian chickens were examined. Collectively, 25 different alleles and 79 genotypes could be found. The observed levels of heterozygosity were 81% in Khorasan and Marandi and 34% in Arian chickens. Our results indicate that LEI0258 diversity in Marandi chickens is higher than in the other populations. Allelic diversity in Iranian chickens is relatively higher than in the local chicken breeds reported for Brazil and Vietnam.

Demonstration of the deleterious impact of feto-maternal MHC compatibility on the success of pregnancy in a macaque model

Event Abstract Back to Event Demonstration of the deleterious impact of feto-maternal MHC compatibility on the success of pregnancy in a macaque model Alice Aarnink1, 2, Edward Mee3, Nicolas Savy4, Nicola Rose3 and Antoine Blancher1, 2* 1 Université Paul Sabatier, Toulouse 3, Laboratoire d'immunogénétique moléculaire (EA3034), France 2 CHU de Toulouse, Laboratoire d'Immunologie, France 3 National Institute for Biological Standards and Control, Division of Virology, United Kingdom 4 Université Paul Sabatier, Toulouse 3, Institut de Mathématiques, France The impact of feto-maternal histocompatibility on reproduction has inspired long-lasting debates. However, after the review of numerous articles, the impact of HLA allele sharing within couples on fecundity remains questionable (1). We decided to explore the impact of MHC feto-maternal compatibility on reproduction in a cynomolgus macaque breeding unit composed of animals originating from Mauritius Island. The Mauritian macaque population presents a very restricted MHC polymorphism (only seven founding haplotypes) due to a strong founding bottleneck (2, 3, 4, 5). The MHC polymorphism was investigated in 237 trios (male, female and offspring) using 17 microsatellite markers distributed across the MHC (Figure 1) (6). Haplotypes were confirmed by segregation analysis. We evaluated the relative frequencies of offspring MHC-compatible and MHC-semicompatible with their mother. Among the 237 trios, 106 offsprings were semi-compatible and 47 offsprings were fully compatible with their mother for all MHC markers. This repartition is incompatible with a random distribution with an interval of confidence of 99,9 %. In a second step, we selected 42 trios for which the identity of the father is certain and for which the theoretical probabilities of full compatible and semi-compatible offsprings were equals. We found 11 offsprings fully compatible and 31 offsprings semi-compatible with their respective mother (Figure 2). Again, the observed repartition was clearly outside the interval of confidence of 99 %, and therefore most probably resulted from a selection of the semi-compatible foetuses during pregnancy. We concluded that MHC fully compatible cynomolgus macaque foetuses have a selective survival disadvantage in comparison with foetuses inheriting a paternal MHC haplotype differing from maternal haplotypes. We analysed separately the compatibility of offspring with their mother for MHC class II (5 markers) or MHC class I and III regions (12 markers) in trios for which compatibility and semi-compatibility offspring were equi-probable. For the MHC class II region, among the 87 informative trios, 42 offsprings were full compatible and 45 were semi-compatible with their mother. This repartition does not differ significantly from a random distribution. We deduced that the MHC class II region is not responsible of this selective survival disadvantage of MHC fully compatible foetuses with their mother. For the MHC class I and III region, among the 48 informative trios, only 15 offsprings were full compatible with their mother. This repartition (15-33) is incompatible with a random distribution with an interval of confidence of 98 %. We concluded that the offspring/mother compatibility in the MHC class I and III region, influences the chance of foetus birth. The low density and low polymorphism of markers in MHC class IA, class IB and class III regions did not allow delineating more precisely the most influent region. Figure 1 Figure 2

Immunogenicity of a Recombinant Measles-HIV-1 Clade B Candidate Vaccine

Live attenuated measles virus is one of the most efficient and safest vaccines available, making it an attractive candidate vector for a HIV/AIDS vaccine aimed at eliciting cell-mediated immune responses (CMI). Here we have characterized the potency of CMI responses generated in mice and non-human primates after intramuscular immunisation with a candidate recombinant measles vaccine carrying an HIV-1 insert encoding Clade B Gag, RT and Nef (MV1-F4). Eight Mauritian derived, MHC-typed cynomolgus macaques were immunised with 105 TCID50 of MV1-F4, four of which were boosted 28 days later with the same vaccine. F4 and measles virus (MV)-specific cytokine producing T cell responses were detected in 6 and 7 out of 8 vaccinees, respectively. Vaccinees with either M6 or recombinant MHC haplotypes demonstrated the strongest cytokine responses to F4 peptides. Polyfunctional analysis revealed a pattern of TNFα and IL-2 responses by CD4+ T cells and TNFα and IFNγ responses by CD8+ T cells to F4 peptides. HIV-specific CD4+ and CD8+ T cells expressing cytokines waned in peripheral blood lymphocytes by day 84, but CD8+ T cell responses to F4 peptides could still be detected in lymphoid tissues more than 3 months after vaccination. Anti-F4 and anti-MV antibody responses were detected in 6 and 8 out of 8 vaccinees, respectively. Titres of anti-F4 and MV antibodies were boosted in vaccinees that received a second immunisation. MV1-F4 carrying HIV-1 Clade B inserts induces robust boostable immunity in non-human primates. These results support further exploration of the MV1-F4 vector modality in vaccination strategies that may limit HIV-1 infectivity.

Double Haploidentical Hematopoietic Stem Cell Transplantation (HSCT) Enhances Anti-Tumor Activity After Transplant

Abstract 1897We have previously shown that haploidentical (HI) HSCT with low dose donor T-cell infusion provides a survival advantage in tumor bearing mice when compared to parent F1 or MHC-matched transplant models. We suggest that MHC difference in HI-HSCT generates early T-cell clonal activation against the unshared MHC haplotype, which eliminates residual tumor cells that express the unshared MHC haplotype. However, alteration in MHC antigen expression is a significant contributor to tumor escape from graft-versus-tumor (GVT) activity. Recent haploidentical transplant data revealed that uniparental disomy, the loss of the HLA haplotype, is a clinically relevant mechanism of tumor escape that leads to post-transplant leukemia relapse. Murine renal cell carcinoma, RENCA-TGL, cell line normally expresses only H2Kd as a MHC molecule. Therefore, in our haploidentical transplant model, T cell clonal activity is usually restricted against H2Kd molecule only. For circumventing the single haplotype expression of tumor model, we transfected this cell line with a H2Kb expressing vector, pAcGFP-NeoR-H2Kb, and generated stable clones with G418 selection. The clone that has more than 95% H2Kb expression used for in vivo experiments. Both tumor cell lines, i.e. parental and transfected clone, had similar in vivo tumor growth acceptance and growth rate. We then used two different haploidentical donors that were targeting different MHC haplotypes. Lethally irradiated B6D2F1 (H2Kb/d) mice were transplanted with T cell depleted bone marrow (TCD-BM) from either B6C3F1 (H-2Kb/k) (single haplo-1; SH1), or C3D2F1 (H2Kk/d) (single haplo 2; SH2) or both donor mice with low-dose (1×105) T-cells. In some experiments, animals were also injected either H2Kd or H2Kb/d expressing RENCA-TGL cells for the evaluation of GVT activity.Bone marrow (BM), spleens and thymi were harvested from recipients of single and double HI-HSCT at day 35 and showed similar cellularities. Interestingly, spleen and bone marrow had similar chimerism from both donors in DH-HSCT. There were no early transplant mortality, graft failure, weight loss and GVHD scoring difference among the double or single-haploidentical transplant recipients. In two other sets of experiments, we followed the tumor growth and the survival of tumor bearing mice after transplant. The recipients of DH-HSCT showed a better survival and GVT activity than the recipients of SH-HSCT in RENCA-TGL (H2Kb/d) bearing tumor model. These observations confirmed that MHC targeting plays a prominent role in tumor surveillance, and immune targeting the unshared MHC haplotype with haploidentical transplant induce remarkable survival advantage. Double HI-HSCT provides an unique anti-tumor activity that continues to exert GVT effect, even in case of MHC haplotype loss. Disclosures:No relevant conflicts of interest to declare.

Narrow Groove and Restricted Anchors of MHC Class I Molecule BF2*0401 Plus Peptide Transporter Restriction Can Explain Disease Susceptibility of B4 Chickens

The MHC has genetic associations with many diseases, often due to differences in presentation of antigenic peptides by polymorphic MHC molecules to T lymphocytes of the immune system. In chickens, only a single classical class I molecule in each MHC haplotype is expressed well due to coevolution with the polymorphic TAPs which means that resistance and susceptibility to infectious pathogens are particularly easy to observe. Previously, structures of chicken MHC class I molecule BF2*2101 from B21 haplotype showed an unusually large peptide-binding groove that accommodates a broad spectrum of peptides to present as epitopes to CTLs, explaining the MHC-determined resistance of B21 chickens to Marek's disease. In this study, we report the crystal structure of BF2*0401 from the B4 (also known as B13) haplotype, showing a highly positively charged surface hitherto unobserved in other MHC molecules, as well as a remarkably narrow groove due to the allele-specific residues with bulky side chains. Together, these properties limit the number of epitope peptides that can bind this class I molecule. However, peptide-binding assays show that in vitro, BF2*0401 can bind a wider variety of peptides than are found on the surface of B4 cells. Thus, a combination of the specificities of the polymorphic TAP and the MHC results in a very limited set of BF2*0401 peptides with negatively charged anchors to be presented to T lymphocytes.

Dual signaling by innate and adaptive immune receptors is required for TLR7-induced B-cell–mediated autoimmunity

Toll-like receptor 7 (Tlr7) has been linked to systemic lupus disease incidence in humans and mice, but how TLR7 potentiates autoimmunity is unclear. We used a Tlr7 transgenic (tg) mouse model to investigate the cellular and molecular events required to induce spontaneous autoimmunity through increased TLR7 activity. We determined that Tlr7 exerts B-cell-intrinsic effects in promoting spontaneous germinal center (GC) and plasmablast B-cell development, and that these B-cell subsets are dependent on T-cell-derived signals through CD40L and SLAM-associated protein (SAP), but not IL-17. Antigen specificity also factored into TLR7-induced disease, as both a restricted T cell receptor (TCR) specificity and MHC haplotype H2(k/k) protected Tlr7tg mice from spontaneous lymphocyte activation and autoantibody production. Inflammatory myeloid cell expansion and autoimmunity did not develop in Tlr7tgIgH(-/-) mice, suggesting either that spontaneous TLR7 activation does not occur in dendritic cells, or, if it does occur, cannot drive these events in the absence of B-cell aid. These data indicate that autoimmune disease in Tlr7tg mice is contingent upon B cells receiving stimulation both through innate pathways and T-cell-derived signals and suggest a codependent relationship between B cells and T cells in the development of autoimmunity.

57-OR

Aim Studies demonstrating MHC haplotype matching by linkage between HLA-A, -B and -DRB1 in unrelated Haematopoietic Cell Transplantation (HCT), have demonstrated to reduce acute GVHD but increase the risk of disease recurrence. Thus, knowing the haplotype matching status of HCT donors and recipients may influence the selection of unrelated donors. Currently, there are no efficient ways of determining the degree of MHC haplotype matching, other than inference based on HLA-A, B, C, DRB1 and DQB1. This approach may be unreliable because of the haplotype promiscuity of some of the HLA alleles and the large physical distance between HLA-B/C and HLA-DRB1/DQB1. The aim of this study was to identify new markers to assist with haplotype matching between HCT donors and patients. Methods We sequenced the region within the MHC haplotype block that includes the complement genes (the Gamma block) in homozygous workshop DNA and identified candidate SNP’s using Assign-ATF sequence analysis software. PCR-SSP’s were then developed to type specifically for the candidate SNP’s which were then used for typing on MHC typed sample donors. Results Testing on homozygous DNA and MHC typed sample donors identified SNP’s exclusively specific for 17 common MHC Extended, or Ancestral, Haplotypes and a further 15 SNP’s shared between a small number of haplotypes. Furthermore, testing on HLA identical sample donors has revealed Gamma block mismatching does occur, indicating a high likelihood that the genomic content of a significant portion of the MHC is likely to be mismatched between the donors of these samples. Conclusions We have developed SSP assays, called Gamma-Type™, for MHC haplotype block specific SNPs, located in a critical region of the MHC between HLA-B/C and HLA-DRB1/DQB1. Gamma-Type™ is an important tool for assessing the likelihood of haplotype matching between HCT donors and recipients.

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Aim To determine the nature and frequency of novel HLA Class I alleles characterised by non-coding polymorphisms. Methods Assign-SBT v3.6+ enables the analysis of SBT sequence data against cDNA and genomic libraries from the IMGT/HLA database. We are in the process of analysing SBT sequence trace data from 4 sites in the USA, Australia and Europe from previously typed individuals. Samples with mismatches in non-coding regions of available class I data were recorded for the location and type of sequence mismatch. Results To date, data from 907 samples have been analysed. A total of 118 samples have sequence mismatches, from 1 or more loci, with the IMGT v3.7 allele database. The 118 samples have a total of 21 new alleles with 10 of the 21 alleles (3 × HLA-A alleles, 3 × HLA-B alleles and 4 × HLA-C alleles) being identified in multiple samples across different laboratories. When the new alleles are analysed in conjunction with additional HLA alleles typed in each individual, some of the alleles appear to be unique to specific MHC haplotypes, either as complete extended (or Ancestral) haplotypes or just the HLA-B/C genomic block. The following haplotype specific alleles and predicted haplotypes have been identified to date: A ∗ 25:01:01-B ∗ 18:01:01new-C ∗ 07:01:01-DRB1 ∗ 15:01:01 A ∗ 11:01:01-B ∗ 35:01:01-C ∗ 04:01:01new1-DRB1 ∗ 01:03 B ∗ 15:01:01new-C ∗ 04:01:01 B ∗ 44:02:01new-C ∗ 07:04 B ∗ 44:02:01-C ∗ 05:01:01new (These represent a subset of B ∗ 44:02:01-C ∗ 05:01:01 haplotypes) B ∗ 41:01-C ∗ 17:01:01new. As distinct from the haplotype specific alleles described above at least one allele, an additional novel C ∗ 04:01:01 allele is found on multiple HLA-B/C haplotypes. Conclusions It has been suggested that haplotype matching in HLA matched unrelated bone donor/recipient pairs affects acute GvHD and disease relapse. Matching for the alleles described above provides additional haplotype information. Further studies are required to determine outcomes in donor recipient pairs when the newly described alleles are matched v mismatched.

Ex Vivo SIV-Specific CD8 T Cell Responses in Heterozygous Animals Are Primarily Directed against Peptides Presented by a Single MHC Haplotype

The presence of certain MHC class I alleles is correlated with remarkable control of HIV and SIV, indicating that specific CD8 T cell responses can effectively reduce viral replication. It remains unclear whether epitopic breadth is an important feature of this control. Previous studies have suggested that individuals heterozygous at the MHC class I loci survive longer and/or progress more slowly than those who are homozygous at these loci, perhaps due to increased breadth of the CD8 T cell response. We used Mauritian cynomolgus macaques with defined MHC haplotypes and viral inhibition assays to directly compare CD8 T cell efficacy in MHC-heterozygous and homozygous individuals. Surprisingly, we found that cells from heterozygotes suppress viral replication most effectively on target cells from animals homozygous for only one of two potential haplotypes. The same heterozygous effector cells did not effectively inhibit viral replication as effectively on the target cells homozygous for the other haplotype. These results indicate that the greater potential breadth of CD8 T cell responses present in heterozygous animals does not necessarily lead to greater antiviral efficacy and suggest that SIV-specific CD8 T cell responses in heterozygous animals have a skewed focus toward epitopes restricted by a single haplotype.

Subcongenic Analyses Reveal Complex Interactions between Distal Chromosome 4 Genes Controlling Diabetogenic B Cells and CD4 T Cells in Nonobese Diabetic Mice

Autoimmune type 1 diabetes (T1D) in humans and NOD mice results from interactions between multiple susceptibility genes (termed Idd) located within and outside the MHC. Despite sharing ∼88% of their genome with NOD mice, including the H2(g7) MHC haplotype and other important Idd genes, the closely related nonobese resistant (NOR) strain fails to develop T1D because of resistance alleles in residual genomic regions derived from C57BLKS mice mapping to chromosomes (Chr.) 1, 2, and 4. We previously produced a NOD background strain with a greatly decreased incidence of T1D as the result of a NOR-derived 44.31-Mb congenic region on distal Chr. 4 containing disease-resistance alleles that decrease the pathogenic activity of autoreactive B and CD4 T cells. In this study, a series of subcongenic strains for the NOR-derived Chr. 4 region was used to significantly refine genetic loci regulating diabetogenic B and CD4 T cell activity. Analyses of these subcongenic strains revealed the presence of at least two NOR-origin T1D resistance genes within this region. A 6.22-Mb region between rs13477999 and D4Mit32, not previously known to contain a locus affecting T1D susceptibility and now designated Idd25, was found to contain the main NOR gene(s) dampening diabetogenic B cell activity, with Ephb2 and/or Padi2 being strong candidates as the causal variants. Penetrance of this Idd25 effect was influenced by genes in surrounding regions controlling B cell responsiveness and anergy induction. Conversely, the gene(s) controlling pathogenic CD4 T cell activity was mapped to a more proximal 24.26-Mb region between the rs3674285 and D4Mit203 markers.

Major histocompatibility complex class I chain related gene‐A microsatellite polymorphism shows secondary association with type 1 diabetes and celiac disease in North Indians

Microsatellite polymorphism in exon 5 of major histocompatibility complex class I chain related gene-A (MIC-A) has been implicated in the etiology of autoimmune diseases including type 1 diabetes (T1D) and celiac disease (CD). In this study on North Indian population, the MIC-A5.1 allele, carrying a premature termination codon in transmembrane region, was observed with increased frequency in T1D (29.6%, odds ratio OR = 2.1, P = 0.00017) and CD patients (40.3%, OR = 3.37, P = 1.67E-05) than in controls (16.7%). When the MIC-A5.1 association was adjusted for linkage with human leukocyte antigen (HLA)-DR3, the statistical significance of the association was abolished. This implies that the observed association of MIC-A5.1 is due to its linkage disequilibrium (D' = 0.94) with HLA-B8-DR3-DQ2 haplotype and is secondary to the overall association with DR3 positive MHC haplotypes.

Identification of Quantitative Trait Loci in Experimental Epidermolysis Bullosa Acquisita

Epidermolysis bullosa acquisita (EBA) is a chronic mucocutaneous autoimmune skin blistering disease. Several lines of evidence underscore the contribution of autoantibodies against type VII collagen (COL7) to the pathogenesis of EBA. Furthermore, EBA susceptibility is associated with the MHC haplotype in patients (HLA-DR2) and in immunization-induced EBA in mice (H2s). The latter study indicated an additional contribution of non-MHC genes to disease susceptibility. To identify non-MHC genes controlling EBA susceptibility, we intercrossed EBA-susceptible MRL/MpJ with EBA-resistant NZM2410/J and BXD2/TyJ as well as Cast mice. Mice of the fourth generation of this four-way autoimmune-prone advanced intercross line were immunized with a fragment of murine COL7 to induce EBA. Anti-COL7 autoantibodies were detected in 84% of mice, whereas deposition of complement at the dermal-epidermal junction (DEJ) was observed in 50% of the animals; 33% of immunized mice presented with overt clinical EBA. Onset of clinical disease was associated with several quantitative trait loci (QTLs) located on chromosomes 9, 12, 14, and 19, whereas maximum disease severity was linked to QTLs on chromosomes 1, 15, and 19. This more detailed insight into the pathogenesis of EBA may eventually lead to new treatment strategies for EBA and other autoantibody-mediated diseases.

Insights into MHC evolution provided by interesting genes on Gallus gallus chromosome 16 (167.10)

Abstract The MHC is viewed as ancient and polymorphic as result of enduring selection by diverse pathogens. But even now little is known about MHC polymorphism outside of a few mammalian species. There is little evidence as to how this region contributions in resistance to infectious disease. The MHC of the domesticated chicken (Gallus gallus) has long been observed to influence disease resistance. With a significant portion of the G. gallus MHC sequenced it is now possible to begin to examine individual loci in detail. Our studies have provided evidence for three diverse features contributing to G. gallus MHC diversity and polymorphism: 1) It has become clear that chicken natural killer cells distinguish among different MHC class I isoforms. Natural killing of target cells can be stimulated or inhibited by the expression of different MHC class I alleles. So it seems that innate immunity likely contributes to the long-observed association between chicken MHC haplotype and disease. 2) Expression of BG1, a polymorphic MHC inhibitory receptor contributing in MHC-linked resistance to a herpesvirus-induced lymphoma, is modulated in at least one allele by a retroviral insert targeted by endogenous miRNA. 3) By combining trisomy mapping with array Comparative Genomic Hybridization (aCGH) we have been able to assign to chicken chromosome 16 unmapped genomic sequence contigs containing additional genes long posited to be critical in maintaining pathogen selected MHC diversity.