Triplet repeat polymorphism in the transmembrane region of the MICA gene in celiac disease

Celiac disease (CD) is characterized by a striking expansion of gamma delta T cells in the intestine. These cells interact with MICA, a cell surface protein encoded by a major histocompatibility complex gene. We investigated whether MICA gene polymorphism could contribute to susceptibility to CD. DNA typing for HLA-DR, DQA1, DQB1, TNF-308, TNFa, TNFb and a triplet repeat polymorphism in the transmembrane region of the MICA gene were carried out. We performed case-control stratified association studies and transmission disequilibrium tests. Our results indicate that although there is no primary association between MICA polymorphism and CD, there is, in addition to HLA-DQ, a second susceptibility locus on the 8.1 ancestral haplotype in strong linkage disequilibrium with MICA A5.1 allele.     

HLA-DRB1基因多态性与克山病及其核心家系的关系研究

目的探讨HLA-DRB1基因多态性在我国北方克山病地区的分布特征及其与克山病核心家系的关联和连锁。方法采用聚合酶链反应-序列特异性寡核苷酸探针(polymerase chain reaction-sequence specific oligonucleotide probing,PCR-SSOP)技术,对118例克山病(Keshan disease,KD)患者HLA-DRB1基因进行分型,其中潜在型KD63例,慢型KD55例,65名正常人为对照;采用单倍型相对风险(haplotype based haplotype relative risk,HHRR)和传递不平衡检验(transmission disequilibrium test,TDT)方法对该基因在18个KD核心家系中的分布进行关联和连锁分析。结果(1)在KD患者和对照人群中,HLA-DRB1位点共检出13种等位基因;(2)DR7等位基因在KD组中的分布频率显著低于对照组(P<0.01,OR=0.1695);(3)DR7等位基因在慢型KD中的分布频率显著低于对照组(P<0.01,OR=0.091),而在潜在型KD中的分布频率与对照组比较差异无统计学意义;(4)DR15等位基因与KD显著关联(χ2=9.32,P<0.01),并与KD易感位点连锁(χ2=7.40,P<0.01)。结论KD可能存在遗传易感性,HLA-DRB1的DR7等位基因可能是KD保护性基因,携带DR7等位基因的KD患者可能不易发展为慢型KD,DR15等位基因可能与KD易感基因连锁。     

Heterogeneity of vitamin D receptor gene association with celiac disease and type 1 diabetes mellitus

Objective: Vitamin D has been shown to exert multiple immunomodulatory effects and is known to suppress T-cell activation by binding to the vitamin D receptor (VDR). To determine whether VDR gene polymorphisms are related to the susceptibility to celiac disease, we investigated its implication as a candidate gene in the Basque population. Because celiac disease and type 1 diabetes share common susceptibility loci, we also analyzed families with type 1 diabetes mellitus.

Methods: A total of 37 families with celiac disease and 64 type 1 diabetic families of Basque origin with at least one affected offspring were genotyped for four VDR restriction-site polymorphisms (Fok I, Bsm I, Apa I and Taq I). The AFBAC approach was used to test for association.

Results: Comparison of VDR genotypes of the patients with those of 88 healthy individuals identified “ff” as a risk genotype for celiac disease [p = 0.01; OR = 3.45 (1.12–10.79)]. On the other hand, a significantly higher frequency of haplotype “fBAt” was observed in the type 1 diabetic group [p_c = 0.02; OR = 4.4 (1.5–15.3)].

Conclusion: Our findings suggest that polymorphisms within the vitamin D receptor gene are markers of susceptibility to or protection from autoimmune diseases, although, at least in the Basque population, association of VDR variants with celiac disease and type 1 diabetes seems to be heterogeneous.     

MHC class I chain-related gene B promoter polymorphisms and celiac disease

The possibility that susceptibility to celiac disease (CD) might be influenced by the MHC class I chain-related gene family, MICA and MICB, has been previously reported. In this study, we analyzed the MICB promoter and examined the association of the polymorphisms found within such in a group of CD patients. To study the MICB promoter we sequenced the 5' flanking region of MICB gene in DNA from homozygous B-lymphoblastoid cell lines corresponding to the most frequent MICB alleles found in our population (MICB*00502, MICB*002, MICB*004, and MICB*008). DNA from a MICB*003 homozygous individual was also analyzed. Sequence analysis revealed six single nucleotide polymorphisms located at positions 45860 C/A, 45862 G/C, 45877 C/G, 46113 A/C, 46219 G/C, and 46286 G/C and an insertion of 2 bp --/AG at position 45944 according to the published genomic sequence. Those polymorphisms were found to be associated in four different haplotypes corresponding to different MICB alleles. Subsequently, 126 CD subjects and 117 healthy controls were typed by polymerase chain reaction using sequence-specific primers for these polymorphisms. MICB promoter polymorphism haplotypes were also found in our population and showed strong linkage disequilibrium with MICB alleles. MICB promoter polymorphism Haplotype 3, included in MICB*002 and MICB*008 alleles, was found to be overrepresented in CD patients (79.4% CD patients vs 45.3% healthy controls; p(c) < 0.0001; OR = 4.64; CI 95% = 2.64-8.16). Both MICB*008 and MICB*002 alleles were found as part of the CD susceptibility extended haplotypes B8/DR3/DQ2, B18/DR3/DQ2, and DR4/DQ8.     

Identification of a new HLA-DRB1*04 allele, DRB1*0437

In this report we describe the identification of a novel DRB1*04 allele, DRB1*0437, found in a Spanish individual. The routine HLA typing, in the context of bone marrow transplantation, by polymerase chain reaction-sequence-based typing (PCR-SBT) made possible the identification of this new allele. This allele is identical to DRB1*0402 except for a single nucleotide substitution at position 286 (A-->C), changing the encoded Isoleucine to a Leucine. The DRB1*0437 allele conserves the same two acidic residues at codons 70 and 71 that confer to DRB1*0402 its association to some autoimmune diseases.     

MHC class I chain-related gene A transmembrane polymorphism in Spanish women with breast cancer

The NKG2D–major histocompatibility complex class I-related chain A (MICA) system plays a key role in the antitumoral immune response. We studied five alleles of a microsatellite in the MICA transmembrane region; one of which ( MICA-A5.1 ) gives rise to a truncated protein. The MICA-A5 allele was reduced in breast cancer patients compared with healthy controls ( P  = 0.04). Given the association between the HLA-B7 allele and the susceptibility to breast cancer in our area, we also analyzed the distribution of the frequency of the MICA alleles in human leukocyte antigen (HLA)-B7 patients compared with patients with the other alleles. The MICA-A5.1 allele was increased in HLA-B7 patients ( P  = 0.0003). These results suggest that the MICA-A5 allele appears to confer protection against human breast cancer and that the MICA-A5.1 appears to increase the susceptibility to breast cancer in HLA-B7 patients in our area.     

HLA-DRB1*0301等位基因与Graves病的关系

目的 探讨HLA-DRB1*0301等位基因在粤西湛江沿海地区Graves病(GD)发病中的作用.方法 选取65例初诊GD病人和正常对照50例并采用多聚酶链反应-序列特异性引物(PCR-SSP)技术检测HLA-DRB1*0301等位基因的表达频率.结果 初诊GD病人HLA-DRBl*0301等位基因的表达频率显著高于正常对照组(P＜0.005).结论 HLA-DRB1*0301等位基因可能是粤西湛江地区GD的易感基因.     

HLA-DRB1*04 and susceptibility to type 1 diabetes mellitus in a German/Belgian family and German case-control study. The Belgian Diabetes Registry

HLA-DR4 is a primary disease association marker in type 1 diabetes mellitus (IDDM). We therefore analyzed the transmission of 228 DR4+ haplotypes in 183 families with an IDDM proband (95 from Germany and 88 from Belgium). In a separate case-control data set, we investigated the HLA-DRB1*04 and DQ allele distribution in 245 IDDM patients and 177 controls from Germany, all DR4 positive. HLA-DRB1 *0401 and *0402 linked to DQB1 *0302 were significantly more often transmitted to patients in the studied families (81% and 89%) in contrast to DRB1 *0401-DQB1 *0301 (33%). The case-control study of HLA-DQB1 *0302+ individuals revealed -DRB1 *0405 to be more frequent in patients with IDDM and HLA-DRB1 *0403 and -DRB1 *0404 to be less frequent. HLA-DQA1 *0102-DQB1 *0602 and -DQA1 *0501-DQB1 *0301 in trans complementation with DRB1 *0401-DQB1 *0302 were also significantly less frequent in IDDM patients (P<3x 10(-7) and P<0.02). In conclusion, HLA-DRB1 *0403 and -DQB1*0301 alleles in cis as well as protective DQ haplotypes in trans, confer dominant protection against IDDM in a German / Belgian population.     

Immobilized MHC class I chain-related protein A synergizes with IL-15 and soluble 4-1BB ligand to expand NK cells with high cytotoxicity ex vivo

Major histocompatibility complex (MHC) class I chain-related protein A (MICA), which is a ligand for human NKG2D, is expressed by a variety of epithelial tumor cells and promotes the activation of natural killer (NK), CD8⁺ and γδ-T cells. Although ectopic expression of MICA on tumor cells elicits anti-tumor responses, soluble MICA downregulates the activities of lymphocytes. In this study, we showed that recombinant, immobilized MICA (iMICA) molecules coated on plastic wells weakly promote peripheral NK cell activation, secretion of interferon (IFN)-γ and degranulation without inducing apoptosis. In addition, iMICA synergized with IL-15 and soluble 4-1BB ligand (s4-1BBL) to expand NK cells 25- to 42-fold in a 13-day culture, whereas NK cells stimulated only with IL-15 and s4-1BBL expanded 10- to 16-fold. In contrast to NK cells expanded by IL-15 and s4-1BBL stimulation, NK cells expanded long term in the presence of iMICA exhibited increased cytotoxicity against leukemia cells. These results suggest that large numbers of NK cells with high cytotoxicity can be generated by stimulation with IL-15 and s4-1BBL in the presence of iMICA and that these cells can be used for adoptive cancer immunotherapy.     

Identification of two new HLA-DRB1 alleles: HLA-DRB1*1350 and DRB1*140502

Two new HLA-DRB1 alleles have been found by using high-resolution sequence-based typing. The two sequences have been officially named DRB1*1350 (HWS10001327-AY048687) and DRB1*140502 (HWS10001790-AY129430). DRB1*1350 differs from DRB1*110101 by two amino acids at positions 37 (Y-->N) and 58 (A-->E). This allele may arise from gene conversion between DRB1*110101 and DRB1*130201 or DRB1*030101, which are commonly found in Taiwan populations. The other allele, DRB1*140502, obtained from a patient with rheumatoid arthritis, differs from DRB1*140501 at codon 58 (GCC-->GCT). However, it causes no change in amino acid sequence and would therefore not have direct clinical implications.     

Suppressed immune profile in children with combined type 1 diabetes and celiac disease

Children diagnosed with a combination of type 1 diabetes (T1D) and celiac disease (CD) show a dysregulated T helper type 1 (Th1)/Th17 response. Besides the cellular involvement, several soluble immune markers are involved in the autoimmune process of both T1D and CD. Only few studies have examined the peripheral pattern of different cytokines, chemokines and acute-phase proteins (APP) in children with combined T1D and CD. To our knowledge, no studies have evaluated the serum levels of adipocytokines and matrix metalloproteinases (MMPs) in this context. The purpose of the present study was to acquire more knowledge and to gain deeper understanding regarding the peripheral immunoregulatory milieu in children with both T1D and CD. The study included children diagnosed with both T1D and CD (n = 18), children with T1D (n = 27) or CD (n = 16) and reference children (n = 42). Sera were collected and analysis of 28 immune markers (cytokines, chemokines, APPs, adipocytokines and MMPs) was performed using the Luminex technique. The major findings showed that children with a double diagnosis had lower serum levels of interleukin (IL)-22, monocyte chemoattractant protein (MIP)-1α, monocyte chemoattractant protein (MCP)-1, procalcitonin, fibrinogen, visfatin and matrix metalloproteinase (MMP)-2. These results indicate a suppressed immune profile in children with combined T1D and CD, including Th17 cytokines, chemokines, APPs, adipocytokines and MMPs. We conclude that, besides cytokines and chemokines, other immune markers, e.g. APPs, adipocytokines and MMPs, are of importance for further investigations to elucidate the heterogeneous immune processes present in patients diagnosed with T1D in combination with CD.     

High frequency of low-risk human leukocyte antigen class II genotypes in latent celiac disease

Human leukocyte antigen (HLA) class II genotypes in latent celiac disease, a clinical variant of celiac disease (CD) have been scarcely studied. The aim of this work was to investigate whether latent CD and CD share similar frequencies of HLA class II genotypes. HLA class II genotypes of CD patients compared with controls were subdivided in the following at-risk groups: DQB1*02/DQB1*02 (43.0%, odds ratio [OR] 8.02, p < 0.0001), DQB1*0302/DQB1*02 (12.2%, OR 2.77, p = 0.0002), DQB1*02/DQB1*X (39.2%, OR 1.23, p = 0.1903), DQB1*0302/DQB1*X (3.4%, OR 0.35, p = 0.0064) and DQB1*X/DQB1*X (0.8%, OR 0.01, p = 0.0001) where X is neither DQB1*0302 nor DQB1*02. Next, HLA class II genotypes of 21 latent CD patients were compared with the above at-risk groups. Only one latent CD patient (4.8%) was found in the high risk DQB1*02/DQB1*02 group, three (14.3%) were DQB1*0302/DQB1*02, one (4.8%) was DQB1*0302/DQB1*X and the remaining 16 (76.2%) showed the DQB1*02/DQB1*X genotype. Noteworthy, the only 1 patient with the DQB1*02/DQB1*02 high risk genotype did not carry the DR3-DQB1*02/DR3-DQB1*02 or the DR3-DQB1*02/DR7-DQB1*02 but the uncommon DR3-DQB1*02/DR4-DQB1*02 genotype. These data suggest that latent CD is prevalently associated with low-risk HLA class II genotypes.     

The functional R620W variant of the PTPN22 gene is associated with celiac disease

The functional (R620W) variant of human PTPN22 (protein tyrosine phosphatase non-receptor 22) gene has been implicated in the risk to several autoimmune disorders, including type 1 diabetes, Graves' disease, rheumatoid arthritis and systemic lupus erythematosus. In an association study of this single nucleotide polymorphism with celiac disease (CD), comparison of 262 young diagnosis patients and 214 adult controls from Spain showed a higher frequency of the minor allele in the CD group (9.7% vs 5.6% in controls; P =  0.018), suggestive of an increased genetic risk to the disease (odds ratio = 1.82; 95% confidence interval 1.1–3.0). These results support the role of PTPN22 as a general autoimmunity locus involved in tolerance induction in the thymus.     

新疆柯尔克孜族HLA-DRB1基因的多态性

目的:旨在研究新疆柯尔克孜族HLA-DRB1位点等位基因的多态性.方法:采用聚合酶链反应-序列特异引物法(PCR-SSP)对新疆地区柯尔克孜族85名健康无关个体进行HLA-DRB1等位基因分型.结果:共检出HLA-DRB1位点等位基因14种,其中高频率的等位基因是HLA-DRB1*03 (0.3769)、 HLA-DRB1*11 (0.1391)、 HLA-DRB1*07 (0.1056),低频率的等位基因是HLA-DRB1*08 (0.0059)、 HLA-DRB1*01 (0.0178)、 HLA-DRB1*1302 (0.0178)、 HLA-DRB1*1401 (0.0118).柯尔克孜族的HLA-DRB1基因频率分布具有中国北方人群的特点,尤其与西北地区汉族和蒙古族人群最为接近(0.156 、 0.237). 结论:提供了新疆地区柯尔克孜族人HLA-DRB1的14种等位基因的基因频率,为该民族的人类学及疾病相关研究提供了参考数据.     

HLA-DRB1等位基因多态性与原因不明习惯性流产相关性研究

目的探讨HLA-DRB1等位基因多态性与原因不明习惯性流产（UHA）相关性。方法采用PCR-SSP方法对36对UHA夫妇（UHA组）进行HLA-DRB1等位基因分型,并与34对正常夫妇（对照组）比较,将结果进行统计学处理。结果HLA-DRB1＊11等位基因在UHA组中的频率分布较对照组明显增高P〈0.05,HLA-DRB1＊04等位基因在UHA组中的频率分布较对照组明显降低P〈0.05;UHA组中妻子HLA-DRB1＊08等位基因频率分布较对照组妻子明显增高P〈0.05,HLA-DRB1＊07等位基因频率分布较对照组妻子明显降低P〈0.05。结论本地区汉族人群HLA-DRB1等位基因与UHA相关,HLA-DRB1＊11等位基因可能是UHA夫妇的易感基因;HLA-DRB1＊08等位基因可能是UHA妻子的易感基因。     

HLA-DRB1* and allergy to Parietaria: linkage and association analyses

In this study, we used the affected sibling-pairs approach to investigate the linkage of HLA (human leukocyte antigen)-DRB1* with phenotypes related to allergy to Parietaria, the most common pollinosis in Mediterranean countries. The study population consisted of 51 nuclear families (235 subjects). Linkage was detected with Parietaria skin test positivity (p < 0.01), presence of IgG and IgE antibodies specific for the major allergen Par o 1 (p < 0.020 and p < 0.025, respectively), and absence of Par o 1-specific IgE (p < 0.020).

High levels of Par o 1-specific IgG were associated with DRB1*1101 and/or DRB1*1104 (p < 0.0001 and p < 0.0119, respectively) in parents and probands. High levels of Par o 1-specific IgE were associated with DRB1*1104 in parents (p < 0.017) and with DRB1*1101 in probands (p < 0.0146). When siblings were categorized according to high/low total IgE levels (125 IU/ml and <125 IU/ml, respectively), high IgE antibody response was associated with DRB1*1104 in siblings with low total IgE (p < 0.034) and with DRB1*1101 in siblings with high total IgE (p < 0.05).

These results demonstrate that HLA-DRB1*, or genes in linkage disequilibrium, contributes to susceptibility to Parietaria allergy and that total IgE levels can discriminate population subsets where different alleles (at the HLA region or at loci in linkage disequilibrium) contribute to control allergen-specific IgE synthesis.     

HLA‐DQB1*02 allele in children with celiac disease: Potential usefulness for screening strategies

Through a retrospective analysis of a real‐life cohort of children with celiac disease (CD), who underwent HLA‐DQ genotyping, we supported our previous findings indicating the presence of HLA‐DQB1*02 allele in at least 90%–95% of pediatric patients. In the present study, reporting the HLA‐DQ analysis from 184 children (age range: 1–16 years) diagnosed with CD in a single centre, we found that 97.29% of all these CD children (n = 179 out of 184 genotyped patients) resulted to be carriers of at least one copy of HLA‐DQB1*02 allele. If a widened screening for CD should result to be appropriate in the pediatric population after further clinical research, this observation might be potentially exploited to consider a two‐step screening strategy, starting with the HLA‐DQB1*02 targeted analysis followed by the specific serology for CD in these predisposed patients only. However, additional and larger studies are needed to support our findings.     

Associations of major histocompatibility complex class I chain-related molecule polymorphisms with Behcet's disease in Caucasian patients

HLA-B*51 is known to be associated with Behcet's disease (BD) in many ethnic groups. The pathogenic gene, however, may lie close to the HLA-B locus and therefore be in linkage disequilibrium with HLA-B*51. On the basis of the proximity of MIC genes to HLA-B, their expression pattern and their affinity for the activating NKG2D receptor on natural killer (NK) cells and gammadelta T cells, these molecules have been postulated as susceptibility factors in BD. DNA from 56 western European Caucasians with BD and 90 Caucasian controls were analysed by polymerase chain reaction using allele-specific primers for MICA and MICB alleles. An increased allele frequency of MICA*009 was found in the BD patient group (25.0%) when compared with the controls (7.2%). This was associated with a corresponding decrease in MICA*008 in the BD patients (36.6%) compared with the controls (46.7%), which was not significant. MICA*009 was strongly associated with the presence of HLA-B*51 in patients and controls. No significant difference in frequency of MICB alleles was found between patients and controls. Both HLA-B*51 and MICA*009 are strongly associated with BD in a pure Caucasian BD patient group, and the two alleles are in linkage disequilibrium. No MICB allele was found to associate significantly with the disease, an unexpected finding considering the close proximity of the MICA and MICB loci. Our results suggest that while MICB does not influence the development of BD, polymorphisms in MICA may be pathogenic, perhaps through the interaction with NK and gammadelta T cells.     

Towards a molecular phototyping system for allelic variants of MICA, encoded by polymorphisms in exons 2, 3 and 4 of MHC class I chain-related genes

In this study we have developed a polymerase chain reaction-sequence-specific primer (PCR-SSP) or phototyping system to analyse the polymorphism of the human MICA gene locus. By scrutinising the reported MICA sequence variations in exons 2, 3 and 4 which encode the extracellular protein domains, we have selected and tested 20 MICA-specific primer mixes that should discriminate between the majority of homozygous and heterozygous combinations of MICA alleles 001-016. We have tested this scheme on DNA prepared from a large number of well-characterised tissue culture cell lines with previously reported MICA nucleotide sequences and found an excellent correlation with the observed PCR-SSP phototypes. We believe that this scheme can also be modified to detect new MICA alleles when they are characterised, as well as be incorporated into standard phototyping protocols to generate allele and haplotype profiles of both classical and non-classical HLA gene loci in test DNA samples.