RESUMEN
Interferons (IFNs) are cytokines that are central to the host defence against viruses and other microorganisms. If not properly regulated, IFNs may contribute to the pathogenesis of inflammatory autoimmune, or infectious diseases. To identify genetic polymorphisms regulating the IFN system we performed an unbiased genome-wide protein-quantitative trait loci (pQTL) mapping of cell-type specific type I and type II IFN receptor levels and their responses in immune cells from 303 healthy individuals. Seven genome-wide significant (p < 5.0E-8) pQTLs were identified. Two independent SNPs that tagged the multiple sclerosis (MS)-protective HLA class I alleles A*02/A*68 and B*44, respectively, were associated with increased levels of IFNAR2 in B and T cells, with the most prominent effect in IgD-CD27+ memory B cells. The increased IFNAR2 levels in B cells were replicated in cells from an independent set of healthy individuals and in MS patients. Despite increased IFNAR2 levels, B and T cells carrying the MS-protective alleles displayed a reduced response to type I IFN stimulation. Expression and methylation-QTL analysis demonstrated increased mRNA expression of the pseudogene HLA-J in B cells carrying the MS-protective class I alleles, possibly driven via methylation-dependent transcriptional regulation. Together these data suggest that the MS-protective effects of HLA class I alleles are unrelated to their antigen-presenting function, and propose a previously unappreciated function of type I IFN signalling in B and T cells in MS immune-pathogenesis.
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Predisposición Genética a la Enfermedad , Antígeno HLA-A2/genética , Esclerosis Múltiple/genética , Sitios de Carácter Cuantitativo/genética , Adulto , Anciano , Anciano de 80 o más Años , Alelos , Linfocitos B/inmunología , Linfocitos B/patología , Femenino , Citometría de Flujo , Antígeno HLA-A2/inmunología , Humanos , Interferón Tipo I/genética , Interferón Tipo I/inmunología , Interferón gamma/genética , Interferón gamma/inmunología , Células Asesinas Naturales/inmunología , Masculino , Persona de Mediana Edad , Esclerosis Múltiple/epidemiología , Esclerosis Múltiple/inmunología , Esclerosis Múltiple/patología , Polimorfismo de Nucleótido Simple/genética , Receptor de Interferón alfa y beta/genética , Receptor de Interferón alfa y beta/inmunología , Receptores de Interferón/genética , Receptores de Interferón/inmunología , Linfocitos T/inmunología , Linfocitos T/patologíaRESUMEN
The genetic background of lupus nephritis (LN) has not been completely elucidated. We performed a case-only study of 2886 SLE patients, including 947 (33%) with LN. Renal biopsies were available from 396 patients. The discovery cohort (Sweden, n = 1091) and replication cohort 1 (US, n = 962) were genotyped on the Immunochip and replication cohort 2 (Denmark/Norway, n = 833) on a custom array. Patients with LN, proliferative nephritis, or LN with end-stage renal disease were compared with SLE without nephritis. Six loci were associated with LN (p < 1 × 10-4, NFKBIA, CACNA1S, ITGA1, BANK1, OR2Y, and ACER3) in the discovery cohort. Variants in BANK1 showed the strongest association with LN in replication cohort 1 (p = 9.5 × 10-4) and proliferative nephritis in a meta-analysis of discovery and replication cohort 1. There was a weak association between BANK1 and LN in replication cohort 2 (p = 0.052), and in the meta-analysis of all three cohorts the association was strengthened (p = 2.2 × 10-7). DNA methylation data in 180 LN patients demonstrated methylation quantitative trait loci (meQTL) effects between a CpG site and BANK1 variants. To conclude, we describe genetic variations in BANK1 associated with LN and evidence for genetic regulation of DNA methylation within the BANK1 locus. This indicates a role for BANK1 in LN pathogenesis.
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Lupus Eritematoso Sistémico , Nefritis Lúpica , Proteínas Adaptadoras Transductoras de Señales/genética , Estudios de Cohortes , Metilación de ADN , Regulación de la Expresión Génica , Genotipo , Humanos , Nefritis Lúpica/genética , Proteínas de la Membrana/genéticaRESUMEN
Primary Sjögren's syndrome (pSS) is considered to be a multifactorial disease, where underlying genetic predisposition, epigenetic mechanisms and environmental factors contribute to disease development. In the last 5 years, the first genome-wide association studies in pSS have been completed. The strongest signal of association lies within the HLA genes, whereas the non-HLA genes IRF5 and STAT4 show consistent associations in multiple ethnicities but with a smaller effect size. The majority of the genetic risk variants are found at intergenic regions and their functional impact has in most cases not been elucidated. Epigenetic mechanisms such as DNA methylation, histone modifications and non-coding RNAs play a role in the pathogenesis of pSS by their modulating effects on gene expression and may constitute a dynamic link between the genome and phenotypic manifestations. This article reviews the hitherto published genetic studies and our current understanding of epigenetic mechanisms in pSS.
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Epigénesis Genética , Predisposición Genética a la Enfermedad , Síndrome de Sjögren/genética , Metilación de ADN , Código de Histonas/genética , HumanosRESUMEN
OBJECTIVES: Clinical presentation of primary Sjögren's syndrome (pSS) varies considerably. A shortage of evidence-based objective markers hinders efficient drug development and most clinical trials have failed to reach primary endpoints. METHODS: We performed a multicentre study to identify patient subgroups based on clinical, immunological and genetic features. Targeted DNA sequencing of 1853 autoimmune-related loci was performed. After quality control, 918 patients with pSS, 1264 controls and 107 045 single nucleotide variants remained for analysis. Replication was performed in 177 patients with pSS and 7672 controls. RESULTS: We found strong signals of association with pSS in the HLA region. Principal component analysis of clinical data distinguished two patient subgroups defined by the presence of SSA/SSB antibodies. We observed an unprecedented high risk of pSS for an association in the HLA-DQA1 locus of odds ratio 6.10 (95% CI: 4.93, 7.54, P=2.2×10-62) in the SSA/SSB-positive subgroup, while absent in the antibody negative group. Three independent signals within the MHC were observed. The two most significant variants in MHC class I and II respectively, identified patients with a higher risk of hypergammaglobulinaemia, leukopenia, anaemia, purpura, major salivary gland swelling and lymphadenopathy. Replication confirmed the association with both MHC class I and II signals confined to SSA/SSB antibody positive pSS. CONCLUSION: Two subgroups of patients with pSS with distinct clinical manifestations can be defined by the presence or absence of SSA/SSB antibodies and genetic markers in the HLA locus. These subgroups should be considered in clinical follow-up, drug development and trial outcomes, for the benefit of both subgroups.
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Autoanticuerpos/sangre , Cadenas alfa de HLA-DQ/genética , Síndrome de Sjögren , Edad de Inicio , Autoinmunidad/genética , Correlación de Datos , Femenino , Marcadores Genéticos/genética , Predisposición Genética a la Enfermedad , Variación Genética , Humanos , Masculino , Persona de Mediana Edad , Noruega/epidemiología , Polimorfismo de Nucleótido Simple , Análisis de Secuencia de ADN/métodos , Síndrome de Sjögren/clasificación , Síndrome de Sjögren/genética , Síndrome de Sjögren/inmunología , Síndrome de Sjögren/fisiopatología , Suecia/epidemiologíaRESUMEN
Primary Sjögren's syndrome (pSS) is a chronic autoimmune rheumatic disease characterized by inflammation of exocrine glands, mainly salivary and lacrimal glands. In addition, pSS may affect multiple other organs resulting in systemic manifestations. Although the precise etiology of pSS remains elusive, pSS is considered to be a multi-factorial disease, where underlying genetic predisposition, environmental factors and epigenetic mechanisms contribute to disease development. Epigenetic mechanisms, such as DNA methylation, histone modifications and non-coding RNAs, may constitute a dynamic link between genome, environment and phenotypic manifestation by their modulating effects on gene expression. A growing body of studies reporting altered epigenetic landscapes in pSS suggests that epigenetic mechanisms play a role in the pathogenesis of pSS, and the reversible nature of epigenetic modifications suggests therapeutic strategies targeting epigenetic dysregulation in pSS. This article reviews our current understanding of epigenetic mechanisms in pSS and discusses implications for novel diagnostic and therapeutic approaches.
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Epigénesis Genética , Síndrome de Sjögren/genética , Metilación de ADN , Código de Histonas , Humanos , Inflamación , ARN no Traducido , Síndrome de Sjögren/inmunologíaRESUMEN
OBJECTIVES: Systemic lupus erythematosus (SLE) is a chronic autoimmune condition with heterogeneous presentation and complex aetiology where DNA methylation changes are emerging as a contributing factor. In order to discover novel epigenetic associations and investigate their relationship to genetic risk for SLE, we analysed DNA methylation profiles in a large collection of patients with SLE and healthy individuals. METHODS: DNA extracted from blood from 548 patients with SLE and 587 healthy controls were analysed on the Illumina HumanMethylation 450 k BeadChip, which targets 485 000 CpG sites across the genome. Single nucleotide polymorphism (SNP) genotype data for 196 524 SNPs on the Illumina ImmunoChip from the same individuals were utilised for methylation quantitative trait loci (cis-meQTLs) analyses. RESULTS: We identified and replicated differentially methylated CpGs (DMCs) in SLE at 7245 CpG sites in the genome. The largest methylation differences were observed at type I interferon-regulated genes which exhibited decreased methylation in SLE. We mapped cis-meQTLs and identified genetic regulation of methylation levels at 466 of the DMCs in SLE. The meQTLs for DMCs in SLE were enriched for genetic association to SLE, and included seven SLE genome-wide association study (GWAS) loci: PTPRC (CD45), MHC-class III, UHRF1BP1, IRF5, IRF7, IKZF3 and UBE2L3. In addition, we observed association between genotype and variance of methylation at 20 DMCs in SLE, including at the HLA-DQB2 locus. CONCLUSIONS: Our results suggest that several of the genetic risk variants for SLE may exert their influence on the phenotype through alteration of DNA methylation levels at regulatory regions of target genes.
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Metilación de ADN/genética , Regulación de la Expresión Génica/genética , Lupus Eritematoso Sistémico/genética , Adulto , Estudios de Casos y Controles , Mapeo Cromosómico , Islas de CpG/genética , Femenino , Predisposición Genética a la Enfermedad , Estudio de Asociación del Genoma Completo , Genotipo , Humanos , Factor 1 Regulador del Interferón/genética , Lupus Eritematoso Sistémico/sangre , Masculino , Persona de Mediana Edad , Polimorfismo de Nucleótido Simple , Sitios de Carácter CuantitativoRESUMEN
OBJECTIVES: Increasing evidence suggests an epigenetic contribution to the pathogenesis of autoimmune diseases, including primary Sjögren's Syndrome (pSS). The aim of this study was to investigate the role of DNA methylation in pSS by analysing multiple tissues from patients and controls. METHODS: Genome-wide DNA methylation profiles were generated using HumanMethylation450K BeadChips for whole blood, CD19+ B cells and minor salivary gland biopsies. Gene expression was analysed in CD19+ B cells by RNA-sequencing. Analysis of genetic regulatory effects on DNA methylation at known pSS risk loci was performed. RESULTS: We identified prominent hypomethylation of interferon (IFN)-regulated genes in whole blood and CD19+ B cells, including at the genes MX1, IFI44L and PARP9, replicating previous reports in pSS, as well as identifying a large number of novel associations. Enrichment for genomic overlap with histone marks for enhancer and promoter regions was observed. We showed for the first time that hypomethylation of IFN-regulated genes in pSS B cells was associated with their increased expression. In minor salivary gland biopsies we observed hypomethylation of the IFN-induced gene OAS2. Pathway and disease analysis resulted in enrichment of antigen presentation, IFN signalling and lymphoproliferative disorders. Evidence for genetic control of methylation levels at known pSS risk loci was observed. CONCLUSIONS: Our study highlights the role of epigenetic regulation of IFN-induced genes in pSS where replication is needed for novel findings. The association with altered gene expression suggests a functional mechanism for differentially methylated CpG sites in pSS aetiology.
Asunto(s)
Metilación de ADN , Epigénesis Genética , Interferones/genética , Síndrome de Sjögren/genética , 2',5'-Oligoadenilato Sintetasa/genética , Adulto , Anciano , Antígenos/genética , Antígenos CD19/genética , Estudios de Casos y Controles , Proteínas del Citoesqueleto/genética , Femenino , Expresión Génica , Estudio de Asociación del Genoma Completo , Humanos , Masculino , Persona de Mediana Edad , Proteínas de Resistencia a Mixovirus/genética , Proteínas de Neoplasias/genética , Poli(ADP-Ribosa) Polimerasas/genética , Glándulas Salivales Menores/patología , Síndrome de Sjögren/sangre , Síndrome de Sjögren/patologíaRESUMEN
OBJECTIVE: Chronic fatigue is a common, disabling and poorly understood phenomenon. Recent studies indicate that epigenetic mechanisms may be involved in the expression of fatigue, a prominent feature of primary SS (pSS). The aim of this study was to investigate whether DNA methylation profiles of whole blood are associated with fatigue in patients with pSS. METHODS: Forty-eight pSS patients with high (n = 24) or low (n = 24) fatigue as measured by a visual analogue scale were included. Genome-wide DNA methylation was investigated using the Illumina HumanMethylation450 BeadChip array. After quality control, a total of 383 358 Cytosine-phosphate-Guanine (CpG) sites remained for further analysis. Age, sex and differential cell count estimates were included as covariates in the association model. A false discovery rate-corrected P < 0.05 was considered significant, and a cut-off of 3% average difference in methylation levels between high- and low-fatigue patients was applied. RESULTS: A total of 251 differentially methylated CpG sites were associated with fatigue. The CpG site with the most pronounced hypomethylation in pSS high fatigue annotated to the SBF2-antisense RNA1 gene. The most distinct hypermethylation was observed at a CpG site annotated to the lymphotoxin alpha gene. Functional pathway analysis of genes with differently methylated CpG sites in subjects with high vs low fatigue revealed enrichment in several pathways associated with innate and adaptive immunity. CONCLUSION: Some genes involved in regulation of the immune system and in inflammation are differently methylated in pSS patients with high vs low fatigue. These findings point to functional networks that may underlie fatigue. Epigenetic changes could constitute a fatigue-regulating mechanism in pSS.
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Metilación de ADN , Epigenómica , Síndrome de Fatiga Crónica/genética , Síndrome de Sjögren/complicaciones , Adulto , Anciano , Nucleótidos de Citosina/genética , Femenino , Estudio de Asociación del Genoma Completo , Humanos , Masculino , Persona de Mediana Edad , Síndrome de Sjögren/genéticaRESUMEN
OBJECTIVE: B cells are important in the pathogenesis of primary Sjögren's syndrome (pSS). Patients positive for Sjögren's syndrome antigen A/Sjögren syndrome antigen B (SSA/SSB) autoantibodies are more prone to systemic disease manifestations and adverse outcomes. We aimed to determine the role of B cell composition, gene expression, and B cell receptor usage in pSS subgroups stratified for SSA/SSB antibodies. METHODS: Over 230,000 B cells were isolated from peripheral blood of patients with pSS (n = 6 SSA-, n = 8 SSA+ single positive and n = 10 SSA/SSB+ double positive) and four healthy controls and processed for single-cell RNA sequencing (scRNA-seq) and single-cell variable, diversity, and joining (VDJ) gene sequencing (scVDJ-seq). RESULTS: We show that SSA/SSB+ patients present the highest and lowest proportion of naïve and memory B cells, respectively, and the highest up-regulation of interferon-induced genes across all B cell subtypes. Differential usage of IGHV showed that IGHV1-69 and IGHV4-30-4 were more often used in all pSS subgroups compared with controls. Memory B cells from SSA/SSB+ patients displayed a higher proportion of cells with unmutated VDJ transcripts compared with other pSS patient groups and controls, indicating altered somatic hypermutation processes. Comparison with previous studies revealed heterogeneous clonotype pools, with little overlap in CDR3 sequences. Joint analysis using scRNA-seq and scVDJ-seq data allowed unsupervised stratification of patients with pSS and identified novel parameters that correlated to disease manifestations and antibody status. CONCLUSION: We describe heterogeneity and molecular characteristics in B cells from patients with pSS, providing clues to intrinsic differences in B cells that affect the phenotype and outcome and allowing stratification of patients with pSS at improved resolution.
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Síndrome de Sjögren , Humanos , Linfocitos B , Autoanticuerpos , FenotipoRESUMEN
Fine mapping and bioinformatic analysis of the DDX6-CXCR5 genetic risk association in Sjögren's Disease (SjD) and Systemic Lupus Erythematosus (SLE) identified five common SNPs with functional evidence in immune cell types: rs4938573, rs57494551, rs4938572, rs4936443, rs7117261. Functional interrogation of nuclear protein binding affinity, enhancer/promoter regulatory activity, and chromatin-chromatin interactions in immune, salivary gland epithelial, and kidney epithelial cells revealed cell type-specific allelic effects for all five SNPs that expanded regulation beyond effects on DDX6 and CXCR5 expression. Mapping the local chromatin regulatory network revealed several additional genes of interest, including lnc-PHLDB1-1. Collectively, functional characterization implicated the risk alleles of these SNPs as modulators of promoter and/or enhancer activities that regulate cell type-specific expression of DDX6, CXCR5, and lnc-PHLDB1-1, among others. Further, these findings emphasize the importance of exploring the functional significance of SNPs in the context of complex chromatin architecture in disease-relevant cell types and tissues.
RESUMEN
AIMS: Activating epidermal growth factor receptor (EGFR) and KRAS mutations characterize molecular subgroups of non-small-cell lung cancer (NSCLC) with a strong predictive value for response to EGFR inhibitor therapy. However, the temporal occurrence and clonal stability of these mutations during the course of cancer progression are debated. The aim of this study was to characterize the presence of EGFR and KRAS mutations in histologically different areas of primary NSCLC lesions. METHODS AND RESULTS: Formalin-fixed paraffin-embedded cancer specimens from six cases with EGFR mutations and five cases with KRAS mutations were selected from a pool of primary resected NSCLC patients. From each tumour, three morphologically distinct areas were manually microdissected and analysed for the presence of mutations. The results demonstrated consistent EGFR and KRAS mutation status in the different histological areas of all primary tumours. CONCLUSION: The results support the concept that activating EGFR and KRAS mutations are oncogenic events that are consistently present throughout the primary tumour independently of histological heterogeneity. Thus, for molecular diagnostics, any part of the tumour is likely to be representative for EGFR and KRAS mutation testing.
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Carcinoma de Pulmón de Células no Pequeñas/genética , Carcinoma de Pulmón de Células no Pequeñas/patología , Receptores ErbB/genética , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/patología , Proteínas Proto-Oncogénicas p21(ras)/genética , Estudios de Cohortes , Análisis Mutacional de ADN , Genes erbB-1 , Humanos , Microdisección , Mutación , Estudios RetrospectivosRESUMEN
OBJECTIVE: Lupus nephritis (LN) is a common and severe manifestation of SLE. The genetic risk for nephritis and progression to end-stage renal disease (ESRD) in patients with LN remains unclear. Herein, we aimed to identify novel genetic associations with LN, focusing on subphenotypes and ESRD. METHODS: We analysed genomic data on 958 patients with SLE (discovery cohort: LN=338) with targeted sequencing data from 1832 immunological pathway genes. We used an independent multiethnic cohort comprising 1226 patients with SLE (LN=603) as a replication dataset. Detailed functional annotation and functional epigenomic enrichment analyses were applied to predict functional effects of the candidate variants. RESULTS: A genetic variant (rs56097910) within the MERTK gene was associated with ESRD in both cohorts, meta-analysis OR=5.4 (2.8 to 10.6); p=1.0×10-6. We observed decreased methylation levels in peripheral blood cells from SLE patients with ESRD, compared with patients without renal SLE (p=2.7×10-4), at one CpG site (cg16333401) in close vicinity to the transcription start site of MERTK and located in a DNAse hypersensitivity region in T and B cells. Rs56097910 is linked to altered MERTK expression in kidney tissue in public eQTL databases. Two loci were replicated for association with proliferative LN: PRDM1 (rs6924535, pmeta=1.6×10-5, OR=0.58) and APOA1BP (NAXE) (rs942960, pmeta=1.2×10-5, OR=2.64). CONCLUSION: We identified a novel genetic risk locus, MERTK, associated with SLE-ESRD using the data from two large SLE cohorts. Through DNA methylation analysis and functional annotation, we showed that the risk could be mediated through regulation of gene expression. Our results suggest that variants in the MERTK gene are important for the risk of developing SLE-ESRD and suggest a role for PRDM1 and APOA1BP in proliferative LN.
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Fallo Renal Crónico , Lupus Eritematoso Sistémico , Nefritis Lúpica , Humanos , Proteínas Tirosina Quinasas , Tirosina Quinasa c-Mer/genética , Lupus Eritematoso Sistémico/complicaciones , Lupus Eritematoso Sistémico/genética , Nefritis Lúpica/complicaciones , Nefritis Lúpica/genética , Fallo Renal Crónico/genéticaRESUMEN
Sjögren's disease is a complex autoimmune disease with twelve established susceptibility loci. This genome-wide association study (GWAS) identifies ten novel genome-wide significant (GWS) regions in Sjögren's cases of European ancestry: CD247, NAB1, PTTG1-MIR146A, PRDM1-ATG5, TNFAIP3, XKR6, MAPT-CRHR1, RPTOR-CHMP6-BAIAP6, TYK2, SYNGR1. Polygenic risk scores yield predictability (AUROC = 0.71) and relative risk of 12.08. Interrogation of bioinformatics databases refine the associations, define local regulatory networks of GWS SNPs from the 95% credible set, and expand the implicated gene list to >40. Many GWS SNPs are eQTLs for genes within topologically associated domains in immune cells and/or eQTLs in the main target tissue, salivary glands.
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Estudio de Asociación del Genoma Completo , Síndrome de Sjögren , Predisposición Genética a la Enfermedad , Humanos , Polimorfismo de Nucleótido Simple , Síndrome de Sjögren/genéticaRESUMEN
Primary Sjögren's syndrome (pSS) is an autoimmune inflammatory disease with profound clinical heterogeneity, where excessive activation of the type I interferon (IFN) system is considered one of the key mechanisms in disease pathogenesis. Here we present a DNA methylation-based IFN system activation score (DNAm IFN score) and investigate its potential associations with sub-phenotypes of pSS. The study comprised 100 Swedish patients with pSS and 587 Swedish controls. For replication, 48 patients with pSS from Stavanger, Norway, were included. IFN scores were calculated from DNA methylation levels at the IFN-induced genes RSAD2, IFIT1 and IFI44L. A high DNAm IFN score, defined as > meancontrols +2SDcontrols (IFN score >4.4), was observed in 59% of pSS patients and in 4% of controls (p=1.3x10-35). Patients with a high DNAm IFN score were on average seven years younger at symptom onset (p=0.017) and at diagnosis (p=3x10-3). The DNAm IFN score levels were significantly higher in pSS positive for both SSA and SSB antibodies compared to SSA/SSB negative patients (pdiscovery=1.9x10-8, preplication=7.8x10-4). In patients positive for both SSA subtypes Ro52 and Ro60, an increased score was identified compared to single positive patients (p=0.022). Analyzing the discovery and replication cohorts together, elevated DNAm IFN scores were observed in pSS with hypergammaglobulinemia (p=2x10-8) and low C4 (p=1.5x10-3) compared to patients without these manifestations. Patients < 70 years with ongoing lymphoma at DNA sampling or lymphoma at follow-up (n=7), presented an increased DNAm IFN score compared to pSS without lymphoma (p=0.025). In conclusion, the DNAm-based IFN score is a promising alternative to mRNA-based scores for identification of patients with activation of the IFN system and may be applied for patient stratification guiding treatment decisions, monitoring and inclusion in clinical trials.
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Metilación de ADN/inmunología , Interferón Tipo I/inmunología , Síndrome de Sjögren/inmunología , Femenino , Humanos , Linfoma/inmunología , Masculino , Persona de Mediana Edad , Fenotipo , ARN Mensajero/inmunologíaRESUMEN
OBJECTIVES: Fatigue is common and severe in primary Sjögren's syndrome (pSS). The aim of this study was to identify genetic determinants of fatigue in pSS through a genome-wide association study. METHODS: Patients with pSS from Norway, Sweden, UK and USA with fatigue and genotype data available were included. After genotype imputation and quality control, 682 patients and 4 966 157 genetic markers were available. Association analysis in each cohort using linear regression with fatigue as a continuous variable and meta-analyses between the cohorts were performed. RESULTS: Meta-analysis of the Norwegian and Swedish cohorts identified five polymorphisms within the same linkage disequilibrium block at the receptor transporter protein 4 (RTP4)/MASP1 locus associated with fatigue with genome-wide significance (GWS) (p<5×10-8). Patients homozygous for the major allele scored 25 mm higher on the fatigue Visual Analogue Scale than patients homozygous for the minor allele. There were no variants associated with fatigue with GWS in meta-analyses of the US/UK cohorts, or all four cohorts. RTP4 expression in pSS B cells was upregulated and positively correlated with the type I interferon score. Expression quantitative trait loci effects in whole blood for fatigue-associated variants at RTP4/MASP1 and levels of RTP4 and MASP1 expression were identified. CONCLUSION: Genetic variations at RTP4/MASP1 are associated with fatigue in Scandinavian pSS patients. RTP4 encodes a Golgi chaperone that influences opioid pain receptor function and MASP1 is involved in complement activation. These results add evidence for genetic influence over fatigue in pSS.
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Síndrome de Sjögren , Alelos , Estudios de Cohortes , Fatiga/epidemiología , Fatiga/genética , Estudio de Asociación del Genoma Completo , Humanos , Serina Proteasas Asociadas a la Proteína de Unión a la Manosa , Síndrome de Sjögren/complicaciones , Síndrome de Sjögren/genéticaRESUMEN
OBJECTIVE: Standard assessment of interferon (IFN) system activity in systemic rheumatic diseases depends on the availability of RNA samples. In this study, we describe and evaluate alternative methods using plasma, serum and DNA samples, exemplified in the IFN-driven disease primary Sjögren's syndrome (pSS). METHODS: Patients with pSS seropositive or negative for anti-SSA/SSB and controls were included. Protein-based IFN (pIFN) scores were calculated from levels of PD-1, CXCL9 and CXCL10. DNA methylation-based (DNAm) IFN scores were calculated from DNAm levels at RSAD2, IFIT1 and IFI44L. Scores were compared with mRNA-based IFN scores measured by quantitative PCR (qPCR), Nanostring or RNA sequencing (RNAseq). RESULTS: mRNA-based IFN scores displayed strong correlations between B cells and monocytes (r=0.93 and 0.95, p<0.0001) and between qPCR and Nanostring measurements (r=0.92 and 0.92, p<0.0001). The pIFN score in plasma and serum was higher in patients compared with controls (p<0.0001) and correlated well with mRNA-based IFN scores (r=0.62-0.79, p<0.0001), as well as with each other (r=0.94, p<0.0001). Concordance of classification as 'high' or 'low' IFN signature between the pIFN score and mRNA-based IFN scores ranged from 79.5% to 88.6%, and the pIFN score was effective at classifying patients and controls (area under the curve, AUC=0.89-0.93, p<0.0001). The DNAm IFN score showed strong correlation to the RNAseq IFN score (r=0.84, p<0.0001) and performed well in classifying patients and controls (AUC=0.96, p<0.0001). CONCLUSIONS: We describe novel methods of assessing IFN system activity in plasma, serum or DNA samples, which may prove particularly valuable in studies where RNA samples are not available.
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Metilación de ADN , Interferón Tipo I/metabolismo , Proteínas/genética , Síndrome de Sjögren/genética , Adulto , Anciano , Biomarcadores/análisis , Estudios de Casos y Controles , Femenino , Humanos , Interferón Tipo I/genética , Masculino , Persona de Mediana Edad , Proteínas/metabolismo , ARN Mensajero/análisis , Reacción en Cadena en Tiempo Real de la Polimerasa , Análisis de Secuencia de ARN , Síndrome de Sjögren/metabolismoRESUMEN
Objectives: To perform a cross-comparative analysis of DNA methylation in patients with systemic lupus erythematosus (SLE), patients with primary Sjögren's syndrome (pSS), and healthy controls addressing the question of epigenetic sharing and aiming to detect disease-specific alterations. Methods: DNA extracted from peripheral blood from 347 cases with SLE, 100 cases with pSS, and 400 healthy controls were analyzed on the Human Methylation 450k array, targeting 485,000 CpG sites across the genome. A linear regression model including age, sex, and blood cell type distribution as covariates was fitted, and association p-values were Bonferroni corrected. A random forest machine learning classifier was designed for prediction of disease status based on DNA methylation data. Results: We established a combined set of 4,945 shared differentially methylated CpG sites (DMCs) in SLE and pSS compared to controls. In pSS, hypomethylation at type I interferon induced genes was mainly driven by patients who were positive for Ro/SSA and/or La/SSB autoantibodies. Analysis of differential methylation between SLE and pSS identified 2,244 DMCs with a majority of sites showing decreased methylation in SLE compared to pSS. The random forest classifier demonstrated good performance in discerning between disease status with an area under the curve (AUC) between 0.83 and 0.96. Conclusions: The majority of differential DNA methylation is shared between SLE and pSS, however, important quantitative differences exist. Our data highlight neutrophil dysregulation as a shared mechanism, emphasizing the role of neutrophils in the pathogenesis of systemic autoimmune diseases. The current study provides evidence for genes and molecular pathways driving common and disease-specific pathogenic mechanisms.
Asunto(s)
Islas de CpG/inmunología , Metilación de ADN/inmunología , Genoma Humano , Lupus Eritematoso Sistémico , Síndrome de Sjögren , Adulto , Anciano , Femenino , Humanos , Lupus Eritematoso Sistémico/genética , Lupus Eritematoso Sistémico/inmunología , Masculino , Persona de Mediana Edad , Síndrome de Sjögren/genética , Síndrome de Sjögren/inmunologíaRESUMEN
Autoimmune diseases (AID) such as systemic lupus erythematosus (SLE), primary Sjögren's syndrome (pSS), and rheumatoid arthritis (RA) are chronic inflammatory diseases in which abnormalities of B cell function play a central role. Although it is widely accepted that autoimmune B cells are hyperactive in vivo, a full understanding of their functional status in AID has not been delineated. Here, we present a detailed analysis of the functional capabilities of AID B cells and dissect the mechanisms underlying altered B cell function. Upon BCR activation, decreased spleen tyrosine kinase (Syk) and Bruton's tyrosine kinase (Btk) phosphorylation was noted in AID memory B cells combined with constitutive co-localization of CD22 and protein tyrosine phosphatase (PTP) non-receptor type 6 (SHP-1) along with hyporesponsiveness to TLR9 signaling, a Syk-dependent response. Similar BCR hyporesponsiveness was also noted specifically in SLE CD27- B cells together with increased PTP activities and increased transcripts for PTPN2, PTPN11, PTPN22, PTPRC, and PTPRO in SLE B cells. Additional studies revealed that repetitive BCR stimulation of normal B cells can induce BCR hyporesponsiveness and that tissue-resident memory B cells from AID patients also exhibited decreased responsiveness immediately ex vivo, suggesting that the hyporesponsive status can be acquired by repeated exposure to autoantigen(s) in vivo. Functional studies to overcome B cell hyporesponsiveness revealed that CD40 co-stimulation increased BCR signaling, induced proliferation, and downregulated PTP expression (PTPN2, PTPN22, and receptor-type PTPs). The data support the conclusion that hyporesponsiveness of AID and especially SLE B cells results from chronic in vivo stimulation through the BCR without T cell help mediated by CD40-CD154 interaction and is manifested by decreased phosphorylation of BCR-related proximal signaling molecules and increased PTPs. The hyporesponsiveness of AID B cells is similar to a form of functional anergy.
Asunto(s)
Enfermedades Autoinmunes/inmunología , Linfocitos B/inmunología , Agammaglobulinemia Tirosina Quinasa/inmunología , Humanos , Proteínas Tirosina Fosfatasas/inmunología , Receptores de Antígenos de Linfocitos B/inmunología , Quinasa Syk/inmunologíaRESUMEN
Genome-wide association studies have identified risk loci for SLE, but a large proportion of the genetic contribution to SLE still remains unexplained. To detect novel risk genes, and to predict an individual's SLE risk we designed a random forest classifier using SNP genotype data generated on the "Immunochip" from 1,160 patients with SLE and 2,711 controls. Using gene importance scores defined by the random forest classifier, we identified 15 potential novel risk genes for SLE. Of them 12 are associated with other autoimmune diseases than SLE, whereas three genes (ZNF804A, CDK1, and MANF) have not previously been associated with autoimmunity. Random forest classification also allowed prediction of patients at risk for lupus nephritis with an area under the curve of 0.94. By allele-specific gene expression analysis we detected cis-regulatory SNPs that affect the expression levels of six of the top 40 genes designed by the random forest analysis, indicating a regulatory role for the identified risk variants. The 40 top genes from the prediction were overrepresented for differential expression in B and T cells according to RNA-sequencing of samples from five healthy donors, with more frequent over-expression in B cells compared to T cells.