RESUMO
Central B cell tolerance, the process restricting the development of many newly generated autoreactive B cells, has been intensely investigated in mouse cells while studies in humans have been hampered by the inability to phenotypically distinguish autoreactive and nonautoreactive immature B cell clones and the difficulty in accessing fresh human bone marrow samples. Using a human immune system mouse model in which all human Igκ+ B cells undergo central tolerance, we discovered that human autoreactive immature B cells exhibit a distinctive phenotype that includes lower activation of ERK and differential expression of CD69, CD81, CXCR4, and other glycoproteins. Human B cells exhibiting these characteristics were observed in fresh human bone marrow tissue biopsy specimens, although differences in marker expression were smaller than in the humanized mouse model. Furthermore, the expression of these markers was slightly altered in autoreactive B cells of humanized mice engrafted with some human immune systems genetically predisposed to autoimmunity. Finally, by treating mice and human immune system mice with a pharmacologic antagonist, we show that signaling by CXCR4 is necessary to prevent both human and mouse autoreactive B cell clones from egressing the bone marrow, indicating that CXCR4 functionally contributes to central B cell tolerance.
Assuntos
Tolerância Central/fisiologia , Células Precursoras de Linfócitos B/metabolismo , Receptores CXCR4/metabolismo , Animais , Autoanticorpos/metabolismo , Autoantígenos/imunologia , Autoimunidade/imunologia , Linfócitos B/imunologia , Medula Óssea/metabolismo , Células da Medula Óssea/citologia , Células da Medula Óssea/metabolismo , Diferenciação Celular/genética , Tolerância Central/imunologia , Feminino , Humanos , Tolerância Imunológica/genética , Recém-Nascido , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Transgênicos , Fenótipo , Células Precursoras de Linfócitos B/fisiologia , Receptores de Antígenos de Linfócitos B/metabolismo , Receptores CXCR4/imunologia , Receptores CXCR4/fisiologia , Transdução de Sinais/genéticaRESUMO
Systemic lupus erythematosus (SLE or lupus) (OMIM: 152700) is a chronic autoimmune disease with debilitating inflammation that affects multiple organ systems. The STAT1-STAT4 locus is one of the first and most highly replicated genetic loci associated with lupus risk. We performed a fine-mapping study to identify plausible causal variants within the STAT1-STAT4 locus associated with increased lupus disease risk. Using complementary frequentist and Bayesian approaches in trans-ancestral Discovery and Replication cohorts, we found one variant whose association with lupus risk is supported across ancestries in both the Discovery and Replication cohorts: rs11889341. In B cell lines from patients with lupus and healthy controls, the lupus risk allele of rs11889341 was associated with increased STAT1 expression. We demonstrated that the transcription factor HMGA1, a member of the HMG transcription factor family with an AT-hook DNA-binding domain, has enriched binding to the risk allele compared with the non-risk allele of rs11889341. We identified a genotype-dependent repressive element in the DNA within the intron of STAT4 surrounding rs11889341. Consistent with expression quantitative trait locus (eQTL) analysis, the lupus risk allele of rs11889341 decreased the activity of this putative repressor. Altogether, we present a plausible molecular mechanism for increased lupus risk at the STAT1-STAT4 locus in which the risk allele of rs11889341, the most probable causal variant, leads to elevated STAT1 expression in B cells due to decreased repressor activity mediated by increased binding of HMGA1.
Assuntos
Alelos , Lúpus Eritematoso Sistêmico/genética , Polimorfismo Genético , Locos de Características Quantitativas , Fator de Transcrição STAT1/genética , Fator de Transcrição STAT4/genética , Feminino , Humanos , Lúpus Eritematoso Sistêmico/epidemiologia , Masculino , Fatores de RiscoRESUMO
Genetic variants at chromosomal region 11q23.3, near the gene ETS1, have been associated with systemic lupus erythematosus (SLE), or lupus, in independent cohorts of Asian ancestry. Several recent studies have implicated ETS1 as a critical driver of immune cell function and differentiation, and mice deficient in ETS1 develop an SLE-like autoimmunity. We performed a fine-mapping study of 14,551 subjects from multi-ancestral cohorts by starting with genotyped variants and imputing to all common variants spanning ETS1. By constructing genetic models via frequentist and Bayesian association methods, we identified 16 variants that are statistically likely to be causal. We functionally assessed each of these variants on the basis of their likelihood of affecting transcription factor binding, miRNA binding, or chromatin state. Of the four variants that we experimentally examined, only rs6590330 differentially binds lysate from B cells. Using mass spectrometry, we found more binding of the transcription factor signal transducer and activator of transcription 1 (STAT1) to DNA near the risk allele of rs6590330 than near the non-risk allele. Immunoblot analysis and chromatin immunoprecipitation of pSTAT1 in B cells heterozygous for rs6590330 confirmed that the risk allele increased binding to the active form of STAT1. Analysis with expression quantitative trait loci indicated that the risk allele of rs6590330 is associated with decreased ETS1 expression in Han Chinese, but not other ancestral cohorts. We propose a model in which the risk allele of rs6590330 is associated with decreased ETS1 expression and increases SLE risk by enhancing the binding of pSTAT1.
Assuntos
Predisposição Genética para Doença , Lúpus Eritematoso Sistêmico/genética , Proteína Proto-Oncogênica c-ets-1/genética , Fator de Transcrição STAT1/genética , Alelos , Animais , Povo Asiático , Teorema de Bayes , Genótipo , Haplótipos , Humanos , Camundongos , Ligação Proteica , Proteína Proto-Oncogênica c-ets-1/metabolismo , Fator de Transcrição STAT1/metabolismoRESUMO
Efforts to identify lupus-associated causal variants in the FAM167A/BLK locus on 8p21 are hampered by highly associated noncausal variants. In this report, we used a trans-population mapping and sequencing strategy to identify a common variant (rs922483) in the proximal BLK promoter and a tri-allelic variant (rs1382568) in the upstream alternative BLK promoter as putative causal variants for association with systemic lupus erythematosus. The risk allele (T) at rs922483 reduced proximal promoter activity and modulated alternative promoter usage. Allelic differences at rs1382568 resulted in altered promoter activity in B progenitor cell lines. Thus, our results demonstrated that both lupus-associated functional variants contribute to the autoimmune disease association by modulating transcription of BLK in B cells and thus potentially altering immune responses.
Assuntos
Lúpus Eritematoso Sistêmico/genética , Regiões Promotoras Genéticas , Transcrição Gênica , Quinases da Família src/genética , Alelos , Cromossomos Humanos Par 8 , Ensaio de Desvio de Mobilidade Eletroforética , Feminino , Predisposição Genética para Doença , Haplótipos , Humanos , Masculino , Polimorfismo de Nucleotídeo ÚnicoRESUMO
OBJECTIVES: Systemic lupus erythematosus (SLE; OMIM 152700) is characterised by the production of antibodies to nuclear antigens. We previously identified variants in complement receptor 2 (CR2/CD21) that were associated with decreased risk of SLE. This study aimed to identify the causal variant for this association. METHODS: Genotyped and imputed genetic variants spanning CR2 were assessed for association with SLE in 15 750 case-control subjects from four ancestral groups. Allele-specific functional effects of associated variants were determined using quantitative real-time PCR, quantitative flow cytometry, electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP)-PCR. RESULTS: The strongest association signal was detected at rs1876453 in intron 1 of CR2 (pmeta=4.2×10(-4), OR 0.85), specifically when subjects were stratified based on the presence of dsDNA autoantibodies (case-control pmeta=7.6×10(-7), OR 0.71; case-only pmeta=1.9×10(-4), OR 0.75). Although allele-specific effects on B cell CR2 mRNA or protein levels were not identified, levels of complement receptor 1 (CR1/CD35) mRNA and protein were significantly higher on B cells of subjects harbouring the minor allele (p=0.0248 and p=0.0006, respectively). The minor allele altered the formation of several DNA protein complexes by EMSA, including one containing CCCTC-binding factor (CTCF), an effect that was confirmed by ChIP-PCR. CONCLUSIONS: These data suggest that rs1876453 in CR2 has long-range effects on gene regulation that decrease susceptibility to lupus. Since the minor allele at rs1876453 is preferentially associated with reduced risk of the highly specific dsDNA autoantibodies that are present in preclinical, active and severe lupus, understanding its mechanisms will have important therapeutic implications.
Assuntos
Anticorpos Antinucleares/sangue , Lúpus Eritematoso Sistêmico/genética , Receptores de Complemento 3d/genética , Adolescente , Adulto , Subpopulações de Linfócitos B/imunologia , Estudos de Casos e Controles , DNA/imunologia , Predisposição Genética para Doença , Variação Genética , Genótipo , Haplótipos , Humanos , Lúpus Eritematoso Sistêmico/imunologia , Pessoa de Meia-Idade , Fenótipo , Polimorfismo de Nucleotídeo Único , Receptores de Complemento 3b/biossíntese , Medição de Risco/métodos , Fatores de Transcrição/metabolismo , Adulto JovemRESUMO
OBJECTIVES: Following up the systemic lupus erythematosus (SLE) genome-wide association studies (GWAS) identification of NMNAT2 at rs2022013, we fine-mapped its 150â kb flanking regions containing NMNAT2 and SMG7 in a 15â 292 case-control multi-ancestry population and tested functions of identified variants. METHODS: We performed genotyping using custom array, imputation by IMPUTE 2.1.2 and allele specific functions using quantitative real-time PCR and luciferase reporter transfections. SLE peripheral blood mononuclear cells (PBMCs) were cultured with small interfering RNAs to measure antinuclear antibody (ANA) and cyto/chemokine levels in supernatants using ELISA. RESULTS: We confirmed association at NMNAT2 in European American (EA) and Amerindian/Hispanic ancestries, and identified independent signal at SMG7 tagged by rs2702178 in EA only (p=2.4×10-8, OR=1.23 (95% CI 1.14 to 1.32)). In complete linkage disequilibrium with rs2702178, rs2275675 in the promoter region robustly associated with SMG7 mRNA levels in multiple expression quantitative trait locus (eQTL) datasets. Its risk allele was dose-dependently associated with decreased SMG7 mRNA levels in PBMCs of 86 patients with SLE and 119 controls (p=1.1×10-3 and 6.8×10-8, respectively) and conferred reduced transcription activity in transfected HEK-293 (human embryonic kidney cell line) and Raji cells (p=0.0035 and 0.0037, respectively). As a critical component in the nonsense-mediated mRNA decay pathway, SMG7 could regulate autoantigens including ribonucleoprotein (RNP) and Smith (Sm). We showed SMG7 mRNA levels in PBMCs correlated inversely with ANA titres of patients with SLE (r=-0.31, p=0.01), and SMG7 knockdown increased levels of ANA IgG and chemokine (C-C motif) ligand 19 in SLE PBMCs (p=2.0×10-5 and 2.0×10-4, respectively). CONCLUSION: We confirmed NMNAT2 and identified independent SMG7 association with SLE. The inverse relationship between levels of the risk allele-associated SMG7 mRNAs and ANA suggested the novel contribution of mRNA surveillance pathway to SLE pathogenesis.
Assuntos
Anticorpos Antinucleares/metabolismo , Proteínas de Transporte/genética , Leucócitos Mononucleares/imunologia , Lúpus Eritematoso Sistêmico/genética , Nicotinamida-Nucleotídeo Adenililtransferase/genética , Alelos , Indígena Americano ou Nativo do Alasca/genética , Feminino , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Técnicas de Genotipagem , Células HEK293 , Hispânico ou Latino/genética , Humanos , Desequilíbrio de Ligação , Lúpus Eritematoso Sistêmico/imunologia , Masculino , Linhagem , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Fatores de Risco , População Branca/genéticaRESUMO
We previously reported that the G allele of rs3853839 at 3'untranslated region (UTR) of Toll-like receptor 7 (TLR7) was associated with elevated transcript expression and increased risk for systemic lupus erythematosus (SLE) in 9,274 Eastern Asians [Pâ=â6.5×10(-10), odds ratio (OR) (95%CI)â=â1.27 (1.17-1.36)]. Here, we conducted trans-ancestral fine-mapping in 13,339 subjects including European Americans, African Americans, and Amerindian/Hispanics and confirmed rs3853839 as the only variant within the TLR7-TLR8 region exhibiting consistent and independent association with SLE (Pmetaâ=â7.5×10(-11), ORâ=â1.24 [1.18-1.34]). The risk G allele was associated with significantly increased levels of TLR7 mRNA and protein in peripheral blood mononuclear cells (PBMCs) and elevated luciferase activity of reporter gene in transfected cells. TLR7 3'UTR sequence bearing the non-risk C allele of rs3853839 matches a predicted binding site of microRNA-3148 (miR-3148), suggesting that this microRNA may regulate TLR7 expression. Indeed, miR-3148 levels were inversely correlated with TLR7 transcript levels in PBMCs from SLE patients and controls (R(2)â=â0.255, Pâ=â0.001). Overexpression of miR-3148 in HEK-293 cells led to significant dose-dependent decrease in luciferase activity for construct driven by TLR7 3'UTR segment bearing the C allele (Pâ=â0.0003). Compared with the G-allele construct, the C-allele construct showed greater than two-fold reduction of luciferase activity in the presence of miR-3148. Reduced modulation by miR-3148 conferred slower degradation of the risk G-allele containing TLR7 transcripts, resulting in elevated levels of gene products. These data establish rs3853839 of TLR7 as a shared risk variant of SLE in 22,613 subjects of Asian, EA, AA, and Amerindian/Hispanic ancestries (Pmeta â=â2.0×10(-19), ORâ=â1.25 [1.20-1.32]), which confers allelic effect on transcript turnover via differential binding to the epigenetic factor miR-3148.
Assuntos
Predisposição Genética para Doença , Lúpus Eritematoso Sistêmico/genética , MicroRNAs/genética , Receptor 7 Toll-Like , Regiões 3' não Traduzidas , Negro ou Afro-Americano/genética , Alelos , Povo Asiático/genética , Regulação da Expressão Gênica/genética , Células HEK293 , Hispânico ou Latino/genética , Humanos , Lúpus Eritematoso Sistêmico/metabolismo , Polimorfismo de Nucleotídeo Único , Receptor 7 Toll-Like/genética , Receptor 7 Toll-Like/metabolismo , População BrancaRESUMO
We previously established an 80 kb haplotype upstream of TNFSF4 as a susceptibility locus in the autoimmune disease SLE. SLE-associated alleles at this locus are associated with inflammatory disorders, including atherosclerosis and ischaemic stroke. In Europeans, the TNFSF4 causal variants have remained elusive due to strong linkage disequilibrium exhibited by alleles spanning the region. Using a trans-ancestral approach to fine-map the locus, utilising 17,900 SLE and control subjects including Amerindian/Hispanics (1348 cases, 717 controls), African-Americans (AA) (1529, 2048) and better powered cohorts of Europeans and East Asians, we find strong association of risk alleles in all ethnicities; the AA association replicates in African-American Gullah (152,122). The best evidence of association comes from two adjacent markers: rs2205960-T (P=1.71 × 10(-34) , OR=1.43[1.26-1.60]) and rs1234317-T (P=1.16 × 10(-28) , OR=1.38[1.24-1.54]). Inference of fine-scale recombination rates for all populations tested finds the 80 kb risk and non-risk haplotypes in all except African-Americans. In this population the decay of recombination equates to an 11 kb risk haplotype, anchored in the 5' region proximal to TNFSF4 and tagged by rs2205960-T after 1000 Genomes phase 1 (v3) imputation. Conditional regression analyses delineate the 5' risk signal to rs2205960-T and the independent non-risk signal to rs1234314-C. Our case-only and SLE-control cohorts demonstrate robust association of rs2205960-T with autoantibody production. The rs2205960-T is predicted to form part of a decameric motif which binds NF-κBp65 with increased affinity compared to rs2205960-G. ChIP-seq data also indicate NF-κB interaction with the DNA sequence at this position in LCL cells. Our research suggests association of rs2205960-T with SLE across multiple groups and an independent non-risk signal at rs1234314-C. rs2205960-T is associated with autoantibody production and lymphopenia. Our data confirm a global signal at TNFSF4 and a role for the expressed product at multiple stages of lymphocyte dysregulation during SLE pathogenesis. We confirm the validity of trans-ancestral mapping in a complex trait.
Assuntos
Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Lúpus Eritematoso Sistêmico/genética , Ligante OX40/genética , Negro ou Afro-Americano/genética , Alelos , Povo Asiático/genética , Mapeamento Cromossômico , Feminino , Genótipo , Haplótipos , Hispânico ou Latino/genética , Humanos , Desequilíbrio de Ligação , Lúpus Eritematoso Sistêmico/patologia , Linfócitos/patologia , Masculino , NF-kappa B/genética , Polimorfismo de Nucleotídeo Único , População Branca/genéticaRESUMO
Immunoregulatory cytokine interleukin-10 (IL-10) is elevated in sera from patients with systemic lupus erythematosus (SLE) correlating with disease activity. The established association of IL10 with SLE and other autoimmune diseases led us to fine map causal variant(s) and to explore underlying mechanisms. We assessed 19 tag SNPs, covering the IL10 gene cluster including IL19, IL20 and IL24, for association with SLE in 15,533 case and control subjects from four ancestries. The previously reported IL10 variant, rs3024505 located at 1 kb downstream of IL10, exhibited the strongest association signal and was confirmed for association with SLE in European American (EA) (Pâ=â2.7×10â»8, ORâ=â1.30), but not in non-EA ancestries. SNP imputation conducted in EA dataset identified three additional SLE-associated SNPs tagged by rs3024505 (rs3122605, rs3024493 and rs3024495 located at 9.2 kb upstream, intron 3 and 4 of IL10, respectively), and SLE-risk alleles of these SNPs were dose-dependently associated with elevated levels of IL10 mRNA in PBMCs and circulating IL-10 protein in SLE patients and controls. Using nuclear extracts of peripheral blood cells from SLE patients for electrophoretic mobility shift assays, we identified specific binding of transcription factor Elk-1 to oligodeoxynucleotides containing the risk (G) allele of rs3122605, suggesting rs3122605 as the most likely causal variant regulating IL10 expression. Elk-1 is known to be activated by phosphorylation and nuclear localization to induce transcription. Of interest, phosphorylated Elk-1 (p-Elk-1) detected only in nuclear extracts of SLE PBMCs appeared to increase with disease activity. Co-expression levels of p-Elk-1 and IL-10 were elevated in SLE T, B cells and monocytes, associated with increased disease activity in SLE B cells, and were best downregulated by ERK inhibitor. Taken together, our data suggest that preferential binding of activated Elk-1 to the IL10 rs3122605-G allele upregulates IL10 expression and confers increased risk for SLE in European Americans.
Assuntos
Predisposição Genética para Doença , Interleucina-10/genética , Lúpus Eritematoso Sistêmico/genética , Proteínas Elk-1 do Domínio ets/genética , Alelos , Povo Asiático , Regulação da Expressão Gênica , Estudo de Associação Genômica Ampla , Genótipo , Haplótipos , Hispânico ou Latino , Humanos , Interleucina-10/biossíntese , Íntrons , Lúpus Eritematoso Sistêmico/patologia , Polimorfismo de Nucleotídeo Único , Ligação Proteica , Regulação para Cima , População Branca/genética , Proteínas Elk-1 do Domínio ets/biossínteseRESUMO
Leptin is abnormally elevated in the plasma of patients with systemic lupus erythematosus (SLE), where it is thought to promote and/or sustain pro-inflammatory responses. Whether this association could reflect an increased genetic susceptibility to develop SLE is not known, and studies of genetic associations with leptin-related polymorphisms in SLE patients have been so far inconclusive. Here we genotyped DNA samples from 15,706 SLE patients and healthy matched controls from four different ancestral groups, to correlate polymorphisms of genes of the leptin pathway to risk for SLE. It was found that although several SNPs showed weak associations, those associations did not remain significant after correction for multiple testing. These data do not support associations between defined leptin-related polymorphisms and increased susceptibility to develop SLE.
Assuntos
Predisposição Genética para Doença/genética , Leptina/genética , Lúpus Eritematoso Sistêmico/genética , Polimorfismo de Nucleotídeo Único/genética , Estudos de Casos e Controles , Genótipo , HumanosRESUMO
Systemic lupus erythematosus (SLE) is a chronic heterogeneous autoimmune disorder characterized by the loss of tolerance to self-antigens and dysregulated interferon responses. The etiology of SLE is complex, involving both heritable and environmental factors. Candidate-gene studies and genome-wide association (GWA) scans have been successful in identifying new loci that contribute to disease susceptibility; however, much of the heritable risk has yet to be identified. In this study, we sought to replicate 1,580 variants showing suggestive association with SLE in a previously published GWA scan of European Americans; we tested a multiethnic population consisting of 7,998 SLE cases and 7,492 controls of European, African American, Asian, Hispanic, Gullah, and Amerindian ancestry to find association with the disease. Several genes relevant to immunological pathways showed association with SLE. Three loci exceeded the genome-wide significance threshold: interferon regulatory factor 8 (IRF8; rs11644034; p(meta-Euro) = 2.08 × 10(-10)), transmembrane protein 39A (TMEM39A; rs1132200; p(meta-all) = 8.62 × 10(-9)), and 17q21 (rs1453560; p(meta-all) = 3.48 × 10(-10)) between IKAROS family of zinc finger 3 (AIOLOS; IKZF3) and zona pellucida binding protein 2 (ZPBP2). Fine mapping, resequencing, imputation, and haplotype analysis of IRF8 indicated that three independent effects tagged by rs8046526, rs450443, and rs4843869, respectively, were required for risk in individuals of European ancestry. Eleven additional replicated effects (5 × 10(-8) < p(meta-Euro) < 9.99 × 10(-5)) were observed with CFHR1, CADM2, LOC730109/IL12A, LPP, LOC63920, SLU7, ADAMTSL1, C10orf64, OR8D4, FAM19A2, and STXBP6. The results of this study increase the number of confirmed SLE risk loci and identify others warranting further investigation.
Assuntos
Proteínas do Ovo/genética , Predisposição Genética para Doença , Fator de Transcrição Ikaros/genética , Fatores Reguladores de Interferon/genética , Lúpus Eritematoso Sistêmico/genética , Proteínas de Membrana/genética , Povo Asiático/genética , População Negra/genética , Mapeamento Cromossômico , Feminino , Haplótipos/genética , Hispânico ou Latino/genética , Humanos , Indígenas Norte-Americanos/genética , Lúpus Eritematoso Sistêmico/etnologia , Masculino , Polimorfismo de Nucleotídeo Único/genética , Análise de Sequência de DNA , População Branca/genéticaRESUMO
Systemic lupus erythematosus (SLE) is considered to be the prototypic autoimmune disease, with a complex genetic architecture influenced by environmental factors. We sought to replicate a putative association at 11p13 not yet exceeding genome-wide significance (p < 5 × 10(-8)) identified in a genome-wide association study (GWAS). Our GWA scan identified two intergenic SNPs located between PDHX and CD44 showing suggestive evidence of association with SLE in cases of European descent (rs2732552, p = 0.004, odds ratio [OR] = 0.78; rs387619, p = 0.003, OR = 0.78). The replication cohort consisted of >15,000 subjects, including 3562 SLE cases and 3491 controls of European ancestry, 1527 cases and 1811 controls of African American (AA) descent, and 1265 cases and 1260 controls of Asian origin. We observed robust association at both rs2732552 (p = 9.03 × 10(-8), OR = 0.83) and rs387619 (p = 7.7 × 10(-7), OR = 0.83) in the European samples with p(meta) = 1.82 × 10(-9) for rs2732552. The AA and Asian SLE cases also demonstrated association at rs2732552 (p = 5 × 10(-3), OR = 0.81 and p = 4.3 × 10(-4), OR = 0.80, respectively). A meta-analysis of rs2732552 for all racial and ethnic groups studied produced p(meta) = 2.36 × 10(-13). This locus contains multiple regulatory sites that could potentially affect expression and functions of CD44, a cell-surface glycoprotein influencing immunologic, inflammatory, and oncologic phenotypes, or PDHX, a subunit of the pyruvate dehydrogenase complex.
Assuntos
Cromossomos Humanos Par 11/genética , Loci Gênicos , Predisposição Genética para Doença , Receptores de Hialuronatos/genética , Lúpus Eritematoso Sistêmico/genética , Complexo Piruvato Desidrogenase/genética , Negro ou Afro-Americano/genética , Indígena Americano ou Nativo do Alasca/genética , Povo Asiático/genética , Estudos de Coortes , Feminino , Haplótipos , Hispânico ou Latino/genética , Humanos , Desequilíbrio de Ligação , Lúpus Eritematoso Sistêmico/etnologia , Masculino , Polimorfismo de Nucleotídeo Único , População Branca/genéticaRESUMO
Systemic lupus erythematosus (SLE), a complex polygenic autoimmune disease, is associated with increased complement activation. Variants of genes encoding complement regulator factor H (CFH) and five CFH-related proteins (CFHR1-CFHR5) within the chromosome 1q32 locus linked to SLE, have been associated with multiple human diseases and may contribute to dysregulated complement activation predisposing to SLE. We assessed 60 SNPs covering the CFH-CFHRs region for association with SLE in 15,864 case-control subjects derived from four ethnic groups. Significant allelic associations with SLE were detected in European Americans (EA) and African Americans (AA), which could be attributed to an intronic CFH SNP (rs6677604, in intron 11, P(meta)â=â6.6×10(-8), ORâ=â1.18) and an intergenic SNP between CFHR1 and CFHR4 (rs16840639, P(meta)â=â2.9×10(-7), ORâ=â1.17) rather than to previously identified disease-associated CFH exonic SNPs, including I62V, Y402H, A474A, and D936E. In addition, allelic association of rs6677604 with SLE was subsequently confirmed in Asians (AS). Haplotype analysis revealed that the underlying causal variant, tagged by rs6677604 and rs16840639, was localized to a ~146 kb block extending from intron 9 of CFH to downstream of CFHR1. Within this block, the deletion of CFHR3 and CFHR1 (CFHR3-1Δ), a likely causal variant measured using multiplex ligation-dependent probe amplification, was tagged by rs6677604 in EA and AS and rs16840639 in AA, respectively. Deduced from genotypic associations of tag SNPs in EA, AA, and AS, homozygous deletion of CFHR3-1Δ (P(meta)â=â3.2×10(-7), ORâ=â1.47) conferred a higher risk of SLE than heterozygous deletion (P(meta)â=â3.5×10(-4), ORâ=â1.14). These results suggested that the CFHR3-1Δ deletion within the SLE-associated block, but not the previously described exonic SNPs of CFH, might contribute to the development of SLE in EA, AA, and AS, providing new insights into the role of complement regulators in the pathogenesis of SLE.
Assuntos
Antígenos de Neoplasias/genética , Biomarcadores Tumorais/genética , Fator H do Complemento/genética , Predisposição Genética para Doença , Lúpus Eritematoso Sistêmico/genética , Polimorfismo de Nucleotídeo Único , Negro ou Afro-Americano/genética , Alelos , Povo Asiático/genética , Estudos de Casos e Controles , Cromossomos Humanos Par 1/genética , Deleção de Genes , Frequência do Gene , Genótipo , Hispânico ou Latino/genética , Humanos , Íntrons , Lúpus Eritematoso Sistêmico/etnologia , População Branca/genéticaRESUMO
The genetic factors underlying the pathogenesis of lupus nephritis associated with systemic lupus erythematosus are largely unknown, although animal studies indicate that nuclear factor (NF)-κB is involved. We reported previously that a knockin mouse expressing an inactive form of ABIN1 (ABIN1[D485N]) develops lupus-like autoimmune disease and demonstrates enhanced activation of NF-κB and mitogen-activated protein kinases in immune cells after toll-like receptor stimulation. In the current study, we show that ABIN1[D485N] mice develop progressive GN similar to class III and IV lupus nephritis in humans. To investigate the clinical relevance of ABIN1 dysfunction, we genotyped five single-nucleotide polymorphisms in the gene encoding ABIN1, TNIP1, in samples from European-American, African American, Asian, Gullah, and Hispanic participants in the Large Lupus Association Study 2. Comparing cases of systemic lupus erythematosus with nephritis and cases of systemic lupus erythematosus without nephritis revealed strong associations with lupus nephritis at rs7708392 in European Americans and rs4958881 in African Americans. Comparing cases of systemic lupus erythematosus with nephritis and healthy controls revealed a stronger association at rs7708392 in European Americans but not at rs4958881 in African Americans. Our data suggest that variants in the TNIP1 gene are associated with the risk for lupus nephritis and could be mechanistically involved in disease development via aberrant regulation of NF-κB and mitogen-activated protein kinase activity.
Assuntos
Proteínas de Ligação a DNA/fisiologia , Nefrite Lúpica/genética , Animais , Proteínas de Ligação a DNA/genética , Imunofluorescência , Humanos , Rim/patologia , Rim/fisiopatologia , Nefrite Lúpica/etiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , NF-kappa B/fisiologia , Polimorfismo de Nucleotídeo ÚnicoRESUMO
BACKGROUND: Circulating, extracellular RNA is the primary trigger of type I interferon in systemic lupus erythematosus (SLE), and interferon is known to play a central pathogenic role in the disease. RSLV-132 is a catalytically active human RNase molecule fused to human IgG1 Fc designed to digest RNA and thereby decrease the chronic inflammation associated with SLE. The drug was evaluated in a cohort of patients with SLE with moderate-severe cutaneous disease activity and the presence of RNA immune complexes. The primary objective of the study was the assessment of the impact of 13 doses of 10 mg/kg RSLV-132 over 6 months on the mean Cutaneous Lupus Erythematosus Disease Area and Severity Index (CLASI) score. METHODS: Sixty-five patients meeting the entry criteria of a baseline CLASI score of 10 or greater and positivity of at least one of five autoantibodies to RNA-binding proteins (SM/RNP, SSA/Ro, SSB/La, Sm, RNP) were randomly assigned (2:1) to receive 13 doses of RSLV-132 10 mg/kg or placebo, respectively. Participants received study drug for 24 weeks on days 1, 8, 15, 29, 43, 57, 71, 85, 99, 113, 127, 141 and 155 with an end-of-treatment visit on day 169 and a follow-up visit at the end of the study on day 215. The primary objective was assessed on days 85 and 169. Secondary objectives included assessment of systemic disease activity using the Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K), the British Isles Lupus Assessment Group 2004 Index and the Physician's Global Assessment. Data from these instruments were used to calculate the SLE Responder Index 4 (SRI-4) and the British Isles Lupus Assessment Group-based Composite Lupus Assessment (BICLA) scores. RESULTS: The mean CLASI score change from baseline at day 169 was -5.7 (±7.0) in the placebo group and -6.2 (±8.5) in the RSLV-132 group. A subgroup of participants with moderate-severe systemic disease activity and high baseline SLEDAI scores (≥9) were analysed with respect to BICLA and SRI-4 responses. The RSLV-132 treated participants in the high SLEDAI subgroup had a greater percentage of BICLA responses (62% vs 44%) and SRI-4 responses (23% vs 11%) as compared with placebo. A second subgroup of participants with high baseline CLASI scores (≥21) were analysed with respect to BICLA and SRI-4 responses. The RSLV-132 treated participants in the high CLASI subgroup had a greater percentage of BICLA responses (28% vs 8%) and SRI-4 responses (39% vs 8%) as compared with placebo. CONCLUSIONS: Six months of RSLV-132 therapy consisting of a weekly loading dose of RSLV-132 for 1 month, followed by 5 months of biweekly administrations did not significantly improve the mean CLASI score relative to placebo in this cohort of patients with SLE. The study entry criteria selected patients with moderate-severe cutaneous disease activity and no minimum SLEDAI score, which resulted in a wide range of systemic disease activity from inactive to severe as measured by SLEDAI. When the participants with higher SLEDAI and CLASI scores were analysed, a trend towards clinical improvement favouring RSLV-132 was observed. The results warrant further evaluation of RSLV-132 in SLE and suggest that patients with more active systemic disease are most likely to benefit from RNase therapy.
Assuntos
Lúpus Eritematoso Discoide , Lúpus Eritematoso Sistêmico , Proteínas Recombinantes de Fusão , Humanos , Anticorpos Monoclonais Humanizados/uso terapêutico , Resultado do Tratamento , Ribonucleases/uso terapêutico , Imunoglobulina G/uso terapêutico , Lúpus Eritematoso Discoide/induzido quimicamente , Lúpus Eritematoso Discoide/tratamento farmacológico , RNA/uso terapêuticoRESUMO
PURPOSE OF REVIEW: The purpose of this review is to highlight recent progress in defining the effects of variation in the germline DNA sequence on the susceptibility to systemic lupus erythematosus. RECENT FINDINGS: The genetic contributions to lupus susceptibility have been increasingly defined in recent years, although a large proportion of the genetic heritability of this disease remains undiscovered. Various approaches have been taken to determine this 'missing heritability' and to further characterize the known genetic effects in order to more fully elucidate the cause and pathogenesis of this complex and heterogenous disease. SUMMARY: Characterizing the genetic contributions to lupus and their functional effects will advance our understanding of the biology of this disease and aid in the development of new therapeutics.
Assuntos
Lúpus Eritematoso Sistêmico/genética , Doenças Autoimunes/genética , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , HumanosRESUMO
OBJECTIVES: The Xq28 region containing IRAK1 and MECP2 has been identified as a risk locus for systemic lupus erythematosus (SLE) in previous genetic association studies. However, due to the strong linkage disequilibrium between IRAK1 and MECP2, it remains unclear which gene is affected by the underlying causal variant(s) conferring risk of SLE. METHODS: We fine-mapped ≥136 SNPs in a â¼227 kb region on Xq28, containing IRAK1, MECP2 and seven adjacent genes (L1CAM, AVPR2, ARHGAP4, NAA10, RENBP, HCFC1 and TMEM187), for association with SLE in 15 783 case-control subjects derived from four different ancestral groups. RESULTS: Multiple SNPs showed strong association with SLE in European Americans, Asians and Hispanics at p<5×10(-8) with consistent association in subjects with African ancestry. Of these, six SNPs located in the TMEM187-IRAK1-MECP2 region captured the underlying causal variant(s) residing in a common risk haplotype shared by all four ancestral groups. Among them, rs1059702 best explained the Xq28 association signals in conditional testings and exhibited the strongest p value in transancestral meta-analysis (p(meta )= 1.3×10(-27), OR=1.43), and thus was considered to be the most likely causal variant. The risk allele of rs1059702 results in the amino acid substitution S196F in IRAK1 and had previously been shown to increase NF-κB activity in vitro. We also found that the homozygous risk genotype of rs1059702 was associated with lower mRNA levels of MECP2, but not IRAK1, in SLE patients (p=0.0012) and healthy controls (p=0.0064). CONCLUSIONS: These data suggest contributions of both IRAK1 and MECP2 to SLE susceptibility.
Assuntos
Cromossomos Humanos X/genética , Quinases Associadas a Receptores de Interleucina-1/genética , Lúpus Eritematoso Sistêmico/genética , Proteína 2 de Ligação a Metil-CpG/genética , Grupos Raciais/genética , Sequência de Bases , Mapeamento Cromossômico , Predisposição Genética para Doença/genética , Genótipo , Haplótipos , Humanos , Dados de Sequência Molecular , Polimorfismo de Nucleotídeo Único , Reação em Cadeia da Polimerase em Tempo Real , Fatores de RiscoRESUMO
OBJECTIVE: Several confirmed genetic susceptibility loci for lupus have been described. To date, no clear evidence for genetic epistasis in lupus has been established. The aim of this study was to test for gene-gene interactions in a number of known lupus susceptibility loci. METHODS: Eighteen single-nucleotide polymorphisms tagging independent and confirmed lupus susceptibility loci were genotyped in a set of 4,248 patients with lupus and 3,818 normal healthy control subjects of European descent. Epistasis was tested by a 2-step approach using both parametric and nonparametric methods. The false discovery rate (FDR) method was used to correct for multiple testing. RESULTS: We detected and confirmed gene-gene interactions between the HLA region and CTLA4, IRF5, and ITGAM and between PDCD1 and IL21 in patients with lupus. The most significant interaction detected by parametric analysis was between rs3131379 in the HLA region and rs231775 in CTLA4 (interaction odds ratio 1.19, Z = 3.95, P = 7.8 × 10(-5) [FDR ≤0.05], P for multifactor dimensionality reduction = 5.9 × 10(-45)). Importantly, our data suggest that in patients with lupus, the presence of the HLA lupus risk alleles in rs1270942 and rs3131379 increases the odds of also carrying the lupus risk allele in IRF5 (rs2070197) by 17% and 16%, respectively (P = 0.0028 and P = 0.0047, respectively). CONCLUSION: We provide evidence for gene-gene epistasis in systemic lupus erythematosus. These findings support a role for genetic interaction contributing to the complexity of lupus heritability.
Assuntos
Epistasia Genética , Loci Gênicos , Predisposição Genética para Doença , Lúpus Eritematoso Sistêmico/genética , Adulto , Alelos , Feminino , Genótipo , Humanos , Masculino , Polimorfismo de Nucleotídeo ÚnicoRESUMO
OBJECTIVE: Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune disease with significant immune system aberrations resulting from complex heritable genetics as well as environmental factors. We undertook to study the role of TRAF6 as a candidate gene for SLE, since it plays a major role in several signaling pathways that are important for immunity and organ development. METHODS: Fifteen single-nucleotide polymorphisms (SNPs) across TRAF6 were evaluated in 7,490 SLE patients and 6,780 control subjects from different ancestries. Population-based case-control association analyses and meta-analyses were performed. P values, false discovery rate q values, and odds ratios (ORs) with 95% confidence intervals (95% CIs) were calculated. RESULTS: Evidence of associations was detected in multiple SNPs. The best overall P values were obtained for SNPs rs5030437 and rs4755453 (P = 7.85 × 10(-5) and P = 4.73 × 10(-5) , respectively) without significant heterogeneity among populations (P = 0.67 and P = 0.50, respectively, in Q statistic). In addition, SNP rs540386, which was previously reported to be associated with rheumatoid arthritis (RA), was found to be in linkage disequilibrium with these 2 SNPs (r(2) = 0.95) and demonstrated evidence of association with SLE in the same direction (meta-analysis P = 9.15 × 10(-4) , OR 0.89 [95% CI 0.83-0.95]). The presence of thrombocytopenia improved the overall results in different populations (meta-analysis P = 1.99 × 10(-6) , OR 0.57 [95% CI 0.45-0.72], for rs5030470). Finally, evidence of family-based association in 34 African American pedigrees with the presence of thrombocytopenia was detected in 1 available SNP (rs5030437) with a Z score magnitude of 2.28 (P = 0.02) under a dominant model. CONCLUSION: Our data indicate the presence of association of TRAF6 with SLE, consistent with the previous report of association with RA. These data provide further support for the involvement of TRAF6 in the pathogenesis of autoimmunity.
Assuntos
Lúpus Eritematoso Sistêmico/genética , Polimorfismo de Nucleotídeo Único , Fator 6 Associado a Receptor de TNF/genética , Alelos , Estudos de Casos e Controles , Estudos de Coortes , Feminino , Frequência do Gene , Estudos de Associação Genética , Predisposição Genética para Doença , Genótipo , Haplótipos , Humanos , MasculinoRESUMO
OBJECTIVE: American Indian-Europeans, Asians, and African Americans have an excess morbidity from systemic lupus erythematosus (SLE) and a higher prevalence of lupus nephritis than do Caucasians. The aim of this study was to analyze the relationship between genetic ancestry and sociodemographic characteristics and clinical features in a large cohort of American Indian-European SLE patients. METHODS: A total of 2,116 SLE patients of American Indian-European origin and 4,001 SLE patients of European descent for whom we had clinical data were included in the study. Genotyping of 253 continental ancestry-informative markers was performed on the Illumina platform. Structure and Admixture software were used to determine genetic ancestry proportions of each individual. Logistic regression was used to test the association between genetic ancestry and sociodemographic and clinical characteristics. Odds ratios (ORs) were calculated with 95% confidence intervals (95% CIs). RESULTS: The average American Indian genetic ancestry of 2,116 SLE patients was 40.7%. American Indian genetic ancestry conferred increased risks of renal involvement (P < 0.0001, OR 3.50 [95% CI 2.63- 4.63]) and early age at onset (P < 0.0001). American Indian ancestry protected against photosensitivity (P < 0.0001, OR 0.58 [95% CI 0.44-0.76]), oral ulcers (P < 0.0001, OR 0.55 [95% CI 0.42-0.72]), and serositis (P < 0.0001, OR 0.56 [95% CI 0.41-0.75]) after adjustment for age, sex, and age at onset. However, age and sex had stronger effects than genetic ancestry on malar rash, discoid rash, arthritis, and neurologic involvement. CONCLUSION: In general, American Indian genetic ancestry correlates with lower sociodemographic status and increases the risk of developing renal involvement and SLE at an earlier age.