RESUMEN
OBJECTIVE: Two functional single nucleotide polymorphisms (SNP) in the PTPN22 gene (rs24746601 and rs33996649) have been associated with autoimmunity. The aim of this study was to investigate the role of the R263Q SNP for the first time and to re-evaluate the role of the R620W SNP in the genetic predisposition to systemic sclerosis (SSc) susceptibility and clinical phenotypes. METHODS: 3422 SSc patients (2020 with limited cutaneous SSc and 1208 with diffuse cutaneous SSc) and 3638 healthy controls of Caucasian ancestry from an initial case--control set of Spain and seven additional independent replication cohorts were included in our study. Both rs33996649 and rs2476601 PTPN22 polymorphisms were genotyped by TaqMan allelic discrimination assay. A meta-analysis was performed to test the overall effect of these PTPN22 polymorphisms in SSc. RESULTS: The meta-analysis revealed evidence of association of the rs2476601 T allele with SSc susceptibility (p(FDRcorrected)=0.03 pooled, OR 1.15, 95% CI 1.03 to 1.28). In addition, the rs2476601 T allele was significantly associated with anticentromere-positive status (p(FDRcorrected)=0.02 pooled, OR 1.22, 95% CI 1.05 to 1.42). Although the rs33996649 A allele was significantly associated with SSc in the Spanish population (p(FDRcorrected)=0.04, OR 0.58, 95% CI 0.36 to 0.92), this association was not confirmed in the meta-analysis (p=0.36 pooled, OR 0.89, 95% CI 0.72 to 1.1). CONCLUSION: The study suggests that the PTPN22 R620W polymorphism influences SSc genetic susceptibility but the novel R263Q genetic variant does not. These data strengthen evidence that the R620W mutation is a common risk factor in autoimmune diseases.
Asunto(s)
Polimorfismo de Nucleótido Simple , Proteína Tirosina Fosfatasa no Receptora Tipo 22/genética , Esclerodermia Sistémica/genética , Autoanticuerpos/sangre , Estudios de Casos y Controles , Frecuencia de los Genes , Predisposición Genética a la Enfermedad , Genotipo , Humanos , Esclerodermia Sistémica/inmunologíaRESUMEN
OBJECTIVE: To investigate the possible association of the BANK1 gene with genetic susceptibility to systemic sclerosis (SSc) and its subphenotypes. METHODS: A large multicentre case-control association study including 2380 patients with SSc and 3270 healthy controls from six independent case-control sets of Caucasian ancestry (American, Spanish, Dutch, German, Swedish and Italian) was conducted. Three putative functional BANK1 polymorphisms (rs17266594 T/C, rs10516487 G/A, rs3733197 G/A) were selected as genetic markers and genotyped by Taqman 5 allelic discrimination assay. RESULTS: A significant association of the rs10516487 G and rs17266594 T alleles with SSc susceptibility was observed (pooled OR=1.12, 95% CI 1.03 to 1.22; p=0.01 and pooled OR=1.14, 95% CI 1.05 to 1.25; p=0.003, respectively), whereas the rs3733197 genetic variant showed no statistically significant deviation. Stratification for cutaneous SSc phenotype showed that the BANK1 rs10516487 G, rs17266594 T and rs3733197 G alleles were strongly associated with susceptibility to diffuse SSc (dcSSc) (pooled OR=1.20, 95% CI 1.05 to 1.37, p=0.005; pooled OR=1.23, 95% CI 1.08 to 1.41, p=0.001; pooled OR=1.15, 95% CI 1.02 to 1.31, p=0.02, respectively). Similarly, stratification for specific SSc autoantibodies showed that the association of BANK1 rs10516487, rs17266594 and rs3733197 polymorphisms was restricted to the subgroup of patients carrying anti-topoisomerase I antibodies (pooled OR=1.20, 95% CI 1.02 to 1.41, p=0.03; pooled OR=1.24, 95% CI 1.05 to 1.46, p=0.01; pooled OR=1.26, 95% CI 1.07 to 1.47, p=0.004, respectively). CONCLUSION: The results suggest that the BANK1 gene confers susceptibility to SSc in general, and specifically to the dcSSc and anti-topoisomerase I antibody subsets.
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Proteínas Adaptadoras Transductoras de Señales/genética , Proteínas de la Membrana/genética , Esclerodermia Difusa/genética , Población Blanca/genética , Autoanticuerpos/análisis , Estudios de Casos y Controles , Frecuencia de los Genes , Predisposición Genética a la Enfermedad , Genotipo , Humanos , Polimorfismo de Nucleótido Simple , Esclerodermia Difusa/inmunologíaRESUMEN
OBJECTIVE: To identify genetic associations between allograft inflammatory factor 1 (AIF1) and systemic sclerosis (SSc), or its subsets, using a single nucleotide polymorphism (SNP) in a replicate case-control study. METHODS: The frequencies of alleles and genotypes of an SNP, rs2269475, for the AIF1 gene were examined in two large independent cohorts of SSc patients (n = 1015 total), and compared with two groups of normal controls (n = 893 total). Both cases and controls were stratified by ethnicity (Caucasian, African American and Hispanic) and by autoantibody status [anti-centromere antibodies (ACA) and anti-topoisomerase I antibody (ATA)]. RESULTS: The minor T allele and CT/TT genotype frequencies of the AIF1 SNP were not observed more frequently in SSc patients of the three ethnic groups (individually or combined) when compared with controls. On the other hand, T and CT/TT frequencies were significantly increased in ACA-positive Caucasian SSc patients, and all ACA-positive SSc patients (the three ethnic groups combined), when compared with ACA-negative SSc patients and with normal controls, with odds ratios of approximately 1.5. CONCLUSION: The data demonstrate a genetic association between AIF1 and the ACA-positive subset of SSc. This polymorphism is a non-synonymous substitution and therefore likely to represent an important functional change in AIF1. Since vascular pathology is a prominent feature in ACA-positive SSc patients, the observed association with a vasculotrophic inflammatory gene is biologically plausible and warrants further research.
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Anticuerpos Antinucleares/sangre , Centrómero/inmunología , Proteínas de Unión al ADN/genética , Polimorfismo de Nucleótido Simple , Esclerodermia Sistémica/genética , Proteínas de Unión al Calcio , Métodos Epidemiológicos , Frecuencia de los Genes , Predisposición Genética a la Enfermedad , Humanos , Proteínas de Microfilamentos , Esclerodermia Sistémica/etnología , Esclerodermia Sistémica/inmunología , Estados Unidos/epidemiologíaRESUMEN
OBJECTIVE: To differentiate the effects of inhibition of specific small interfering RNA (siRNA) of SPARC (secreted protein, acidic and rich in cysteine) and siRNA of connective tissue growth factor (CTGF) in cultured human fibroblasts, and to identify potential interrelationships between SPARC and CTGF. METHODS: Fibroblasts from skin biopsy specimens of 2 normal individuals were transfected with siRNA of SPARC and siRNA of CTGF. The fibroblasts were stimulated with or without transforming growth factor beta1 (TGFbeta1) and examined by real-time quantitative reverse transcription-polymerase chain reaction to determine the transcription levels of several extracellular matrix genes. RESULTS: After exogenous TGFbeta1 stimulation, both SPARC siRNA and CTGF siRNA showed a protective role against overexpression of collagen genes. Following TGFbeta1 stimulation, SPARC siRNA-transfected fibroblasts showed a greater reduction in expression of the collagen genes compared with CTGF siRNA-transfected fibroblasts, as well as a significantly decreased expression of CTGF (P < 0.05). Using linear structure equations to quantitatively model a genetic network based on expression levels of each gene, a positive regulatory role of SPARC on CTGF, COL1A2, COL3A1, COL11A1, and TIMP3 was observed. However, the regulatory role of CTGF on SPARC appeared to be negative and very small, while the positive regulatory effects of CTGF on COL1A2, COL3A1, COL11A1, and TIMP3 were less than those of SPARC. CONCLUSION: The results of this quantitative comparison support the hypothesis that in these cultured fibroblasts, the regulatory effects of SPARC on some major extracellular matrix structural components are greater than those of CTGF. In addition, SPARC appears to regulate CTGF in a predominantly positive manner, while CTGF may act as a negative feedback control on SPARC following TGFbeta stimulation.
Asunto(s)
Fibroblastos/efectos de los fármacos , Fibroblastos/metabolismo , Proteínas Inmediatas-Precoces/metabolismo , Péptidos y Proteínas de Señalización Intercelular/metabolismo , Osteonectina/metabolismo , Factor de Crecimiento Transformador beta1/farmacología , Células Cultivadas , Colágeno/genética , Colágeno/metabolismo , Factor de Crecimiento del Tejido Conjuntivo , Dermis/citología , Matriz Extracelular/genética , Matriz Extracelular/metabolismo , Regulación de la Expresión Génica , Humanos , Proteínas Inmediatas-Precoces/genética , Péptidos y Proteínas de Señalización Intercelular/genética , Osteonectina/antagonistas & inhibidores , Osteonectina/genética , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/farmacología , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , TransfecciónRESUMEN
AIM: To ascertain the predictive factors of high levels of disease activity in systemic lupus erythematosus (SLE). PATIENTS AND METHODS: Patients with SLE (American College of Radiology criteria), aged >or=16 years, with disease duration
Asunto(s)
Lupus Eritematoso Sistémico/diagnóstico , Adolescente , Adulto , Negro o Afroamericano , Factores de Edad , Métodos Epidemiológicos , Femenino , Hispánicos o Latinos , Humanos , Lupus Eritematoso Sistémico/etnología , Lupus Eritematoso Sistémico/rehabilitación , Masculino , Pronóstico , Índice de Severidad de la Enfermedad , Rol del Enfermo , Apoyo Social , Factores Socioeconómicos , Población BlancaRESUMEN
Renal involvement in systemic lupus erythematosus (SLE) is more frequent in minorities. We examined whether genetic or socioeconomic status (SES) explain these disparities in a large multiethnic (Hispanics from Texas and Puerto Rico, African Americans and Caucasians) SLE cohort. Renal involvement was defined as WHO Class II-V and/or proteinuria (> 0.5 g/24 h or 3+) attributable to SLE and/or abnormal urinary sediment, proteinuria 2+, elevated serum creatinine/ decreased creatinine clearance twice, 6 months apart present any time over the course of the disease. Ancestry informative markers (AIMS) were used to define the admixture proportions in each patient and group. Logistic regression models were examined to determine the percentage variance (R2) in renal involvement related to ethnicity that is explained by socio-economic status (SES) and admixture (adjusting for age, gender and disease duration, basic model). Four-hundred and fifty-nine (out of 575) patients were included; renal involvement occurred in 44.6% Texas Hispanics, 11.3% Puerto Rico Hispanics, 45.8% African Americans, 18.3% Caucasians. SES accounted for 14.5% of the variance due to ethnicity (after adjusting for basic model variables), admixture 36.8% and both, 12.2%; 45.9% of the variance remained unexplained. Alternative models for decreased glomerula filtration rate and end-stage renal disease were comparable in the distribution of the explanatory variables. Our data indicate that genetic factors appear to be more important than SES in explaining the ethnic disparities in the occurrence of renal involvement.
Asunto(s)
Negro o Afroamericano , Hispánicos o Latinos , Lupus Eritematoso Sistémico/etnología , Proteinuria/etiología , Población Blanca , Adulto , Femenino , Estudios de Seguimiento , Tasa de Filtración Glomerular , Humanos , Lupus Eritematoso Sistémico/complicaciones , Lupus Eritematoso Sistémico/psicología , Masculino , Proteinuria/etnología , Proteinuria/fisiopatología , Factores de Riesgo , Factores Socioeconómicos , Estados Unidos/epidemiologíaRESUMEN
OBJECTIVE: To obtain a global view of the immunological alterations occurring in early systemic sclerosis (SSc) by transcriptional profiling of peripheral blood cells (PBCs). METHODS: Oligonucleotide microarrays were used to compare PBC gene expression profiles in 18 SSc cases (<2 yr duration) and 18 controls matched for race, gender and ethnicity. SSc cases had no prior or current exposure to cytotoxic drugs. PAXgene tubes were used to stabilize RNA during phlebotomy. Changes in gene expression were independently validated by real-time polymerase chain reaction. RESULTS: SSc PBCs demonstrated differential expression of 18 interferon-inducible genes. Six of these genes were identical to the interferon signature genes in lupus peripheral blood mononuclear cells. Notably, SSc PBCs also had increased expression of allograft inflammatory factor (AIF1) and several selectins and integrins involved in cellular adhesion to the endothelium. Global analysis of 284 known biological pathways revealed that 13 were differentially regulated in SSc PBCs, including two pathways (IL2RB and GATA3) that lead to T(H)2 polarization. CONCLUSIONS: Transcriptional profiling reliably discriminates between PBCs from SSc and normal donors despite the fact that they represent a heterogeneous cell population. Multiple biological pathways were differentially regulated in SSc PBCs, but a common thread across these pathways was alterations in protein tyrosine kinase 2beta and mitogen-activated protein kinase signalling. Although the SSc PBC gene expression profile demonstrated some parallels with the lupus interferon gene signature, there was also increased expression of transcripts encoding proteins that target PBCs to the endothelium, which might be relevant to the vasculopathy of SSc.
Asunto(s)
Interferones/genética , Esclerodermia Sistémica/genética , Adulto , Autoinmunidad/genética , Células Sanguíneas/metabolismo , Moléculas de Adhesión Celular/sangre , Moléculas de Adhesión Celular/genética , Endotelio Vascular/metabolismo , Femenino , Perfilación de la Expresión Génica/métodos , Regulación de la Expresión Génica/inmunología , Humanos , Interferones/sangre , Masculino , Persona de Mediana Edad , Familia de Multigenes , Análisis de Secuencia por Matrices de Oligonucleótidos , Reacción en Cadena de la Polimerasa/métodos , Esclerodermia Sistémica/sangre , Esclerodermia Sistémica/inmunología , Transducción de Señal/genéticaRESUMEN
OBJECTIVE: To determine the relationship between the presence of antiphospholipid (aPL) antibodies, hydroxychloroquine use and the occurrence of thrombotic events in patients with systemic lupus erythematosus (SLE). METHODS: Four hundred and forty-two SLE patients from the LUMINA (Lupus in Minorities: Nature vs Nurture) cohort, a multiethnic (Hispanics from Texas, n = 99 and Puerto Rico, n = 36; African Americans, n = 172; and Caucasians, n = 135) cohort, were studied by generalized estimating equation (GEE) to determine the relationship between antiphospholipid (aPL) antibodies (measured as IgG and IgM aPL antibodies and/or the lupus anticoagulant) at enrolment or historically prior to enrolment, hydroxychloroquine use (ever) and the occurrence of thrombotic (central and/or peripheral, arterial and/or venous) events after adjusting for known and possible confounders [socioeconomic-demographic features, smoking, disease activity and damage, serum cholesterol levels, anti-oxidized low-density lipoprotein IgG and IgM antibodies, and high-sensitivity (hs) C-reactive protein]. Postanalysis correlation between aPL and anticardiolipin (aCL) assays was attempted by performing aCL assays on random samples of patients whose aPL status was known. RESULTS: A number of clinical variables were significant in the univariable analyses; however, in the multivariable GEE analyses, only smoking [odds ratio (OR) 2.777, 95% confidence interval (CI) 1.317-5.852] and disease activity as measured by the SLAM (Systemic Lupus Activity Measure) (OR 1.099; 95% CI 1.053-1.147) were significant. In particular, hydroxychloroquine use, which appeared to be protective against thrombotic events in the univariable analyses, was not retained in the multivariable analyses. aPL antibodies were not significant in either analysis. Few additional aPL-positive patients emerged from the validation study. CONCLUSIONS: Smoking and disease activity emerged as important determinants in the occurrence of thrombotic events in our patients. Comprehensive treatment strategies should be directed to both smoking cessation and control of disease activity in patients with SLE.
Asunto(s)
Lupus Eritematoso Sistémico/complicaciones , Trombosis/etiología , Anticuerpos Antifosfolípidos/sangre , Antirreumáticos/uso terapéutico , Métodos Epidemiológicos , Femenino , Humanos , Hidroxicloroquina/uso terapéutico , Lupus Eritematoso Sistémico/tratamiento farmacológico , Lupus Eritematoso Sistémico/etnología , Masculino , Índice de Severidad de la Enfermedad , Fumar/efectos adversos , Trombosis/etnología , Trombosis/inmunologíaRESUMEN
The pathogenesis of systemic sclerosis (SSc) involves complex interactions between activated fibroblasts eventually leading to fibrosis, and impaired immune tolerance characterized by a variety of circulating SSc-specific autoantibodies. The expression of autoantigens in fibroblasts, a key target tissue in SSc, may play an important role in this process. To obtain a global view of this process, we examined gene expression profiles of SSc dermal fibroblasts using cDNA microarrays. The results show that dermal fibroblasts from SSc patients obtained from either affected or unaffected skin displayed a characteristic pattern of increased SSc autoantigen gene expression compared with that from normal controls. In particular, fibrillarin (p = 0.028), centromeric protein B (p = 0.01), centromeric autoantigen P27 (p = 0.042), and RNA polymerase II (220 kDa; p = 0.02) were significantly overexpressed in SSc fibroblasts. Quantitative RT-PCR confirmed overexpression of these autoantigens and also revealed increased levels of DNA topoisomerase I transcripts in SSc fibroblasts compared with normal control fibroblasts (p = 0.0318). The polymyositis/scleroderma autoantigen gene was overexpressed in some SSc patients (p = 0.09). To examine the specificity of these overexpressed autoantigen genes for SSc and its tissue specificity for fibroblasts, cDNA microarrays of dermal fibroblasts from patients with eosinophilic fasciitis and scleromyxedema were studied as well as PBMC and muscle biopsies from SSc patients. None of these tissues showed significant alterations in gene expression of SSc-specific autoantigens. Therefore, SSc-associated autoantigen genes are selectively overexpressed in SSc dermal fibroblasts, a major tissue involved in disease pathogenesis.
Asunto(s)
Autoantígenos/genética , Autoantígenos/metabolismo , Dermis/citología , Fibroblastos/metabolismo , Esclerodermia Sistémica/genética , Esclerodermia Sistémica/inmunología , Enfermedades Autoinmunes/genética , Enfermedades Autoinmunes/inmunología , Células Cultivadas , Perfilación de la Expresión Génica , Humanos , Análisis de Secuencia por Matrices de Oligonucleótidos , ARN Mensajero/biosíntesis , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Activación TranscripcionalRESUMEN
OBJECTIVE: To determine if there are abnormalities in fibrillin 1-containing microfibrils in the extracellular matrix (ECM) of primary dermal fibroblasts explanted from patients with systemic sclerosis (SSc). METHODS: Explanted fibroblasts from unaffected skin of 12 SSc patients were used to examine fibrillin 1-containing microfibrils by immunofluorescence (IF) using a monoclonal antibody (mAb) to fibrillin 1. Metabolic labeling of the fibroblast cultures was used to study the synthesis, secretion, and processing of fibrillin 1, as well as to observe microfibril formation and stability. Microfibrils elaborated by the SSc cells were analyzed by electron microscopy for ultrastructural abnormalities, and the results were confirmed by immunoblotting. RESULTS: Control and SSc fibroblasts displayed a prominent meshwork of fibrillin 1-containing microfibrils when visualized by IF using a fibrillin 1 mAb. Paradoxically, metabolic studies indicated a paucity of fibrillin 1 in the ECM in the majority of the SSc fibroblast strains. Subsequent rotary-shadowed electron microscopy revealed reduced amounts of and ultrastructural abnormalities in the microfibrils elaborated by all strains of SSc cells. Immunoblots confirmed the lack of the high molecular weight form of fibrillin 1 in the SSc fibroblasts of Choctaw American Indians. Finally, in vitro studies indicated that the amount of fibrillin 1 in the ECM of SSc cells diminished at a faster rate than the amount of fibrillin 1 in the ECM of control cells with time. CONCLUSION: Although SSc fibroblasts assemble microfibrils, these microfibrils are unstable, suggesting that an inherent defect of fibrillin 1-containing microfibrils may play a role in the pathogenesis of SSc.
Asunto(s)
Dermis/citología , Fibroblastos/ultraestructura , Microfibrillas/ultraestructura , Proteínas de Microfilamentos/metabolismo , Esclerodermia Sistémica/patología , Adulto , Anciano , Anticuerpos Monoclonales/inmunología , Células Cultivadas , Proteínas de la Matriz Extracelular/inmunología , Proteínas de la Matriz Extracelular/metabolismo , Femenino , Fibrilina-1 , Fibrilinas , Fibroblastos/metabolismo , Técnica del Anticuerpo Fluorescente , Humanos , Cinética , Masculino , Microfibrillas/metabolismo , Proteínas de Microfilamentos/inmunología , Persona de Mediana Edad , Esclerodermia Sistémica/etiología , Esclerodermia Sistémica/metabolismoRESUMEN
Matrix metalloproteinase 1 (MMP-1) is necessary for degradation of interstitial collagen types I, II, and III, which are the major constituents of the extracellular matrix (ECM). Increased expression of MMP-1 has been correlated with invasiveness of certain malignancies and cartilage degradation in rheumatoid arthritis. Increased transcriptional activity of MMP-1 has been reported with a single nucleotide polymorphism (SNP) of the MMP-1 promoter. Systemic sclerosis (SSc) is characterized by increased accumulation and turnover of collagen and other components of ECM. Previous studies have reported increased expression of MMP-1 transcripts in SSc fibroblasts. Therefore, we sought to determine if SSc patients with early disease (< or =5 years) from a multi-ethnic cohort were more or less likely than ethnically-matched normal controls to have an increased frequency of the high promoter activity MMP-1 genotype and whether MMP-1 promoter genotypes correlated with any of the major clinical manifestations of SSc. The results show that the frequency of the high activity promoter genotype in either the heterozygous or homozygous state did not differ significantly between SSc patients and ethnically-matched controls, or between SSc patients with either diffuse or limited scleroderma. Furthermore, MMP-1 promoter genotypes did not significantly correlate with any of the major clinical manifestations of SSc.
Asunto(s)
Metaloproteinasa 1 de la Matriz/genética , Polimorfismo de Nucleótido Simple/genética , Regiones Promotoras Genéticas/genética , Esclerodermia Sistémica/enzimología , Esclerodermia Sistémica/genética , Humanos , Metaloproteinasa 1 de la Matriz/fisiologíaRESUMEN
The glutathione S-transferases (GSTs) are a family of enzymes involved in limiting oxidative damage to tissues. Null alleles for one or more of the GST enzymes, especially GSTM1, reportedly occur more frequently in patients with Sjögren's syndrome and systemic lupus erythematosus who possess certain autoantibodies. Because systemic sclerosis (SSc) is a disease in which oxidative damage has been hypothesized to contribute both to immune dysfunction and tissue damage, we sought to determine if patients from a multi-ethnic cohort of SSc patients with early disease (< or =5 years) were more likely than ethnically-matched normal controls to have null alleles for GSTM1 (M1) and/or GSTT1 (T1), and if the null allele status correlated with any major disease features. The data show that while M1 and T1 null genotypes were not significantly increased in SSc compared to ethnically matched controls, their frequencies (especially T1 nulls) were significantly higher among SSc patients with hypertension and pulmonary involvement. This suggests that GST genotype may be a genetic factor that contributes to clinical disease expression in SSc.
Asunto(s)
Glutatión Transferasa/genética , Lupus Eritematoso Sistémico/enzimología , Síndrome de Sjögren/enzimología , Genotipo , HumanosRESUMEN
Mutations in FBN1 cause the autosomal dominant condition, Marfan syndrome. A single-base mutation that results in a skipping of exon 2 of FBN1 was found in a Marfan patient. By sequencing this proband's entire FBN1 gene and comparing the mutated DNA sequence with proband's unaffected family numbers, we confirmed this alteration was the causative mutation. The skipping of exon 2 creates a frameshift and premature termination codon, and forms a truncated fibrillin-1 composed only of 55 amino acids of N-terminus plus 45 nonsense amino acids. The mRNA transcription levels of the mutated FBN1 allele and the deposition of fibrillin-1 into extracellular matrix in fibroblast cells culture were assessed.
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Empalme Alternativo/genética , Exones , Síndrome de Marfan/genética , Proteínas de Microfilamentos/genética , Adulto , Secuencia de Bases , ADN/química , ADN/genética , Análisis Mutacional de ADN , Salud de la Familia , Femenino , Fibrilina-1 , Fibrilinas , Mutación del Sistema de Lectura , Humanos , Masculino , Síndrome de Marfan/patología , Mutación , LinajeRESUMEN
OBJECTIVE: Previously, we demonstrated with the use of microsatellite markers that a 2-cM haplotype on chromosome 15q containing the fibrillin 1 gene (FBN1) was strongly associated with systemic sclerosis (SSc) in the Choctaw, a population with high SSc prevalence. In this study, all 69 known FBN1 exons were sequenced to ascertain the presence of changes that might show associations with SSc in the Choctaw and Japanese SSc patients and controls. METHODS: Screening of FBN1 exons was accomplished by polymerase chain reaction-based fluorescence sequencing of genomic DNA using single-nucleotide polymorphism (SNP) haplotypes, and their frequencies were determined with a new algorithm that recognizes past recombination events between sites. Haplotype phylogenies were inferred using the median-joining network analysis. RESULTS: Five SNPs were identified in FBN1. They are located in the 5'-untranslated region (SNP-1), exon 15 (SNP-2), intron 17 (SNP-3), exon 27 (SNP-4), and intron 27 (SNP-5). Only SNP-1 (T-->C) demonstrated an association with SSc in the Choctaw. Eleven FBN1 SNP haplotypes were ascertained in the Choctaw population, 2 of which (SNPs 5 and 6) were found only in the SSc patients. These same FBN1 SNP haplotypes were associated with SSc in the Japanese. CONCLUSION: A SNP in the 5'-untranslated region of FBN1 (SNP-1, C allele) was strongly associated with SSc in the Choctaw. Furthermore, this polymorphism is present on 2 unique FBN1 haplotypes found only in Choctaw SSc patients. The same 2 haplotypes demonstrate associations with SSc in the Japanese. These data extend the earlier microsatellite studies and are consistent with the hypothesis that FBN1 or a nearby gene on chromosome 15q is involved in SSc susceptibility in the Choctaw and the Japanese.
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Pueblo Asiatico , Indígenas Norteamericanos , Proteínas de Microfilamentos/genética , Polimorfismo de Nucleótido Simple , Esclerodermia Sistémica/genética , Regiones no Traducidas 5' , ADN/análisis , Cartilla de ADN/química , Exones/genética , Femenino , Fibrilina-1 , Fibrilinas , Frecuencia de los Genes , Haplotipos , Humanos , Japón/epidemiología , Masculino , Datos de Secuencia Molecular , Reacción en Cadena de la Polimerasa , Polimorfismo Conformacional Retorcido-Simple , Esclerodermia Sistémica/etnología , Análisis de Secuencia de ADN , Estados Unidos/epidemiologíaAsunto(s)
Glutatión Transferasa/genética , Lupus Eritematoso Sistémico/genética , Grupos Raciales/genética , Negro o Afroamericano , Alelos , Población Negra/genética , Glutatión Transferasa/deficiencia , Hispánicos o Latinos , Humanos , Lupus Eritematoso Sistémico/etnología , Texas/epidemiología , Población Blanca/genéticaRESUMEN
OBJECTIVE: We previously reported the presence of autoantibodies to the extracellular matrix protein, fibrillin 1, in sera from patients with systemic sclerosis (SSc). These autoantibodies appeared to be highly disease-specific but had significantly different frequencies among ethnic groups. The aims of this study were 3-fold: 1) to determine whether sera from SSc patients of different ethnic backgrounds recognized different antigenic epitopes of fibrillin 1, 2) to determine whether sera from patients with polymyositis/dermatomyositis (PM/DM) with or without interstitial lung disease (ILD) also produced these antibodies, and 3) to determine any correlation of anti-fibrillin 1 antibodies with specific clinical features of SSc, other autoantibodies, or HLA class II alleles in a prospectively studied cohort of SSc patients with early (<5 years' duration) disease (the Genetics versus Environment In Scleroderma Outcome Study [GENISOS] cohort). METHODS: Three recombinant peptides accounting for the N-terminal end, proline-rich C region, and epidermal growth factor-like calcium-binding (EGF-cb) domains of fibrillin 1 were used in a radioimmunoassay to screen sera from a large group of SSc and PM/DM patients and ethnically matched controls. RESULTS: The majority of Choctaw American Indians, Japanese, and African Americans with SSc produced IgM and/or IgG autoantibodies to one or more recombinant fibrillin 1 proteins, while <50% of Caucasians with SSc showed seroreactivity. There were striking ethnic differences in fibrillin 1 antigenic epitope recognition among these ethnic groups. African American SSc sera recognized primarily the N-terminal end, and Caucasian sera mostly recognized the EGF-cb repeats and the proline-rich C region. In contrast, most Choctaw American Indian and Japanese SSc sera appeared to recognize 2 or 3 epitopes, respectively. PM/DM patient sera did not recognize any of the fibrillin 1 epitopes regardless of the presence of ILD. In the prospective, multiethnic GENISOS cohort, the presence of anti-fibrillin 1 antibodies did not correlate with any major clinical manifestations, other autoantibodies, or HLA class II alleles. CONCLUSION: There are striking ethnic differences in antigenic epitope specificity of anti-fibrillin 1 antibodies in patients with SSc, and the majority of SSc patients, except for Caucasians, produce antibodies to fibrillin 1. The antifibrillin response thus far remains specific for scleroderma syndromes, but it does not correlate with any major clinical features, other autoantibodies, or HLA class II alleles.
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Proteínas de Microfilamentos/inmunología , Esclerodermia Sistémica/inmunología , Alelos , Autoanticuerpos/sangre , Estudios de Cohortes , Epítopos/sangre , Fibrilina-1 , Fibrilinas , Antígenos HLA/genética , Humanos , Indígenas Norteamericanos , Japón/etnología , Estudios Prospectivos , Esclerodermia Sistémica/etnología , Esclerodermia Sistémica/genética , Población BlancaRESUMEN
There is increasing evidence that genetic factors play important roles in susceptibility to and expression of systemic sclerosis (SSc), as well as primary Raynaud phenomenon. Familial aggregation for SSc, although infrequent (1.2%-1.5% of SSc families), has now been established, and when compared with population prevalence represents a significant risk factor for the disease and lays a firmer foundation for genetics in etiopathogenesis. Major histocompatibility complex class II alleles increase disease risk in some populations but are more strongly correlated with specific autoantibody profiles. Microchimerism influenced by human leukocyte antigen also remains an intriguing hypothesis. A variety of extracellular matrix genes, including fibrillin-1, have become additional candidates for contributing to what is likely a complex genetic disease. Reviewed here is evidence relating to these concepts, especially new data reported over the last year.
Asunto(s)
Enfermedad de Raynaud/genética , Esclerodermia Sistémica/genética , Predisposición Genética a la Enfermedad , HumanosRESUMEN
OBJECTIVE: Abnormalities of transforming growth factor beta (TGFbeta) and platelet-derived growth factor (PDGF) alpha and beta and/or their receptors have been demonstrated in systemic sclerosis (SSc). This study aimed to determine whether genetic polymorphisms in or near the TGFbeta and PDGF gene families were associated with susceptibility to SSc in a Native American population with a high disease prevalence. METHODS: Genotyping of 5 intragenic polymorphisms within the TGFbeta1 gene and mapping of 35 microsatellites near the genes for TGFbeta1, latent TGFbeta1 binding protein (LTBP1), TGFbeta receptors I and II, PDGFalpha, PDGFbeta, PDGF receptor alpha, and PDGF receptor beta was performed in 19 SSc patients, 76 controls, and 42 family members. Allele distributions and frequencies were examined between SSc patients and controls, and marker haplotypes were examined in families when allele frequencies appeared to be different between patients and controls. RESULTS: Although 1 polymorphism within the TGFbeta1 gene (TGFbeta1) was modestly increased in the SSc patients, this did not maintain statistical significance after correction. Similarly, 1 microsatellite (D9S120) near the TGFbeta receptor I gene (TGFBR1) showed a significant disturbance of allele frequencies between patients and controls; however, it did not form a disease-associated haplotype with other nearby markers. Weak disturbances of markers near PDGFalpha (PDGFA) and PDGFbeta, (PDGFB) also failed to maintain significance after correction. Both PDGF receptor genes (PDGFRA and PDGFRB) also showed no disease associations. CONCLUSION: The results of these preliminary analyses suggest that genetic anomalies of the TGFbeta1 and PDGF gene families are not likely to explain the dysregulation seen in SSc or to account for the susceptibility to SSc in this population.