Association of STAT4 with susceptibility to rheumatoid arthritis and systemic lupus erythematosus in the Japanese population

Rheumatoid arthritis does not share most of the newly identified systemic lupus erythematosus genetic factors

OBJECTIVE

Rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) share some genetic factors such as HLA, PTPN22, STAT4, and 6q23. The aim of this study was to determine whether 9 other SLE genetic factors are also implicated in RA susceptibility.

METHODS

A characteristic single-nucleotide polymorphism (SNP) in each of 9 genetic factors, ITGAM (rs1143679), C8orf13-BLK (rs13277113), TYK2 (rs2304256), 1q25.1 (rs10798269), PXK (rs6445975), KIAA1542 (rs4963128), MECP2 (rs17435), BANK1 (rs17266594), and LY9 (rs509749), was studied in 1,635 patients with RA and 1,906 control subjects from Spain. The rs7574865 SNP in STAT4 was also included. Analyses were conducted globally and after stratification by sex and clinical features (anti-cyclic citrullinated peptide and rheumatoid factor, shared epitope, rheumatoid nodules, radiographic changes, sicca syndrome, and pneumonitis).

RESULTS

No association was observed between RA and any of the 9 newly identified SLE genetic factors. A meta-analysis using previous data was consistent with these results. In addition, there were no significant differences between individuals with and those without each of the clinical features analyzed, except the frequency of the minor allele in the C8orf13-BLK locus that was decreased in patients with sicca syndrome (14.6% versus 22.4% in controls; P = 0.003).

CONCLUSION

None of the 9 recently identified SLE risk factors showed association with RA. Therefore, common genetic factors affecting the pathogenesis of these 2 disorders seem to be limited, revealing that the genetic component contributes to the different expression of these diseases.

The search for lupus biomarkers

Few biomarkers for systemic lupus erythematosus (SLE) have been validated and employed for making clinical decisions. The lack of reliable, specific biomarkers for SLE hampers the proper clinical management of patients with SLE and impedes the development of new lupus therapeutics. This void has led to renewed enthusiasm for identifying biomarkers that precisely and specifically reflect the pathophysiological and clinical changes of SLE. Several laboratory markers have shown early promise as biomarkers for lupus susceptibility, diagnosis and monitoring. These include polymorphisms and copy-number variations of complement C4 and Fcgamma receptor genes (disease susceptibility), cell-bound complement C4d (diagnosis and/or disease activity), CD27(high) plasma cells (disease activity), 'interferon signature' (disease activity) and anti-C1q and anti-NMDA (disease activity and organ involvement). Although these and other promising candidate biomarkers have been identified, they still need to be validated through rigorous, large-scale multicentre studies. This article briefly reviews the historical aspects of lupus biomarkers and summarises current efforts to advance the field.

Variants in TNFAIP3, STAT4, and C12orf30 loci associated with multiple autoimmune diseases are also associated with juvenile idiopathic arthritis

OBJECTIVE

Subtypes of juvenile idiopathic arthritis (JIA) share phenotypic features with other autoimmune disorders. We investigated several genetic variants associated with rheumatoid arthritis (RA) and other autoimmune disorders for association with JIA to test the hypothesis that clinically distinct phenotypes share common genetic susceptibility factors.

METHODS

Cases were 445 children with JIA, and controls were 643 healthy adults. Using the TaqMan assay, subjects were genotyped for 8 single-nucleotide polymorphisms in 7 loci including rs10499194 and rs6920220 in the TNFAIP3 locus, rs6679677 in the RSBN1 locus, rs17696736 in the C12orf30 locus, rs3761847 in the TRAF1/C5 locus, rs2104286 in the IL2RA locus, rs7574865 in the STAT4 locus, and rs2542151 in the PTPN2 locus. Alleles and genotypes were analyzed for association with JIA and JIA subtypes. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated.

RESULTS

The strongest associations with JIA risk or protection were observed for TNFAIP3 variants rs10499194 (OR 0.74 [95% CI 0.61-0.91], P < 0.004) and rs6920220 (OR 1.30 [95% CI 1.05-1.61], P = 0.015). We also observed associations between JIA and both STAT4 (OR 1.24 [95% CI 1.02-1.51], P = 0.029) and C12orf30 (OR 1.20 [95% CI 1.01-1.43], P = 0.041) variants. The PTPN2 variant rs2542151 deviated from Hardy-Weinberg equilibrium and was excluded from analyses. Variants in IL2RA, TRAF1/C5, and RSBN1 were not associated with JIA. After stratification by JIA subtype, the TNFAIP3 and C12orf30 variants were associated with oligoarticular JIA, while the STAT4 variant was associated primarily with polyarticular JIA.

CONCLUSION

We have demonstrated associations between JIA and variants in the TNFAIP3, STAT4, and C12orf30 regions that have previously shown associations with other autoimmune diseases, including RA and systemic lupus erythematosus. Our results suggest that clinically distinct autoimmune phenotypes share common genetic susceptibility factors.

Cigarette Smoking,STAT4andTNFRSF1BPolymorphisms, and Systemic Lupus Erythematosus in a Japanese Population

Objective.

Recent studies have identified signal transducer and activator of transcription 4 (STAT4) as a susceptibility gene for systemic lupus erythematosus (SLE) in different populations. Similarly, tumor necrosis factor receptor superfamily, member 1B (TNFRSF1B) has been reported to be associated with SLE risk in Japanese populations. Along with environmental factors such as smoking, both polymorphisms may modulate an individual’s susceptibility to SLE. We investigated these relationships in a case-control study to evaluate risk factors for SLE among Japanese women.

Methods.

We investigated the relationship of theSTAT4rs7574865 andTNFRSF1Brs1061622 polymorphisms to SLE risk with special reference to their combination and interaction with cigarette smoking among 152 SLE cases and 427 controls.

Results.

The TT genotype ofSTAT4rs7574865 was significantly associated with increased risk of SLE (OR 2.21, 95% CI 1.10–4.68). Subjects with at least one G allele ofTNFRSF1Brs1061622 had an increased risk of SLE (OR 1.56, 95% CI 0.99–2.47). The attributable proportion due to the interaction between theTNFRSF1Brs1061622 genotypes and smoking was estimated to be 0.49 (95% CI 0.07–0.92), indicating that 49% of the excess risk for SLE in smokers with at least one G allele was due to an additive interaction. A lack of significant associations ofSTAT4with smoking was observed. No significant gene-gene interactions were found among polymorphisms ofSTAT4andTNFRSF1B.

Conclusion.

Our findings suggest that the association between cigarette smoking and SLE could be differentiated by theTNFRSF1Brs1061622 T allele among female Japanese subjects. This preliminary exploratory result should be confirmed in a larger study.

Association between the rs7574865 polymorphism of STAT4 and rheumatoid arthritis: a meta-analysis

The aim of this study was to determine whether the rs7574865 polymorphism of STAT4 (signal transducers and activators of transcription 4) confers susceptibility to rheumatoid arthritis (RA) in populations with different ethnicities. A meta-analysis was conducted on the T allele of the STAT4 rs7574865 polymorphism in 15 studies containing 16,088 RA patients and 16,509 normal control subjects. Meta-analysis revealed an association between RA and the STAT4 rs7574865 T allele in all subjects (OR = 1.271, 95% CI = 1.197-1.350, P < 0.001). Furthermore, the STAT4 rs7574865 T allele was found to be significantly associated with RA in Europeans and Asians (OR = 1.300, 95% CI = 1.195-1.414, P < 0.001; OR = 1.216, 95% CI = 1.135-1.303, P < 0.001). Stratification of RA patients according to the presence of anti-CCP antibody revealed a statistically significant association between the T allele and RA in both anti-CCP-positive and -negative RA patients versus controls. Europeans had the lowest (21.4%) and Asians had the highest (32.0%) prevalence of the T allele among the populations studied. In conclusion, this meta-analysis confirms that the STAT4 rs7574865 polymorphism is associated with RA susceptibility in different ethnic groups, and that its prevalence is ethnicity dependent.

Confirmation of STAT4, IL2/IL21, and CTLA4 polymorphisms in rheumatoid arthritis

OBJECTIVE

Recent advances have led to novel identification of genetic polymorphisms that are associated with susceptibility to rheumatoid arthritis (RA). Currently, 5 loci (HLA, PTPN22, TRAF1/C5, TNFAIP3, and STAT4) have been consistently reported, whereas others have been observed less systematically. The aim of the present study was to independently replicate 3 recently described RA susceptibility loci, STAT4, IL2/IL21, and CTLA4, in a large Dutch case-control cohort, and to perform a meta-analysis of all published studies to date and investigate the relevance of the findings in clinically well-defined subgroups of RA patients with or without autoantibodies.

METHODS

The STAT4, IL2/IL21, and CTLA4 gene polymorphisms (rs7574865, rs6822844, and rs3087243, respectively) were genotyped in 877 RA patients and 866 healthy individuals. A meta-analysis of all published studies of disease association with these polymorphisms was performed using the Mantel-Haenszel fixed-effects method.

RESULTS

An association of STAT4, IL2/IL21, and CTLA4 with RA was detected in Dutch patients (odds ratio [OR] 1.19 [P=0.031], OR 0.84 [P=0.051], and OR 0.87 [P=0.041], respectively). Results from the meta-analysis confirmed an association of all 3 polymorphisms with RA in Caucasians (OR 1.24 [P=1.66x10(-11)], OR 0.78 [P=5.6x10(-5)], and OR 0.91 [P=1.8x10(-3)], respectively). The meta-analysis also revealed that STAT4 predisposed to disease development equally in patients with autoantibodies and those without autoantibodies, and that CTLA4 enhanced the development of anti-citrullinated protein antibody (ACPA)-positive RA as compared with ACPA-negative RA.

CONCLUSION

Our results replicate and firmly establish the association of STAT4 and CTLA4 with RA and provide highly suggestive evidence for IL2/IL21 loci as a risk factor for RA. Given the strong statistical power of our meta-analysis to confirm a true-positive association, these findings provide considerable support for the involvement of CTLA4 in distinct subsets of RA patients.

Association of STAT4 polymorphism with rheumatoid arthritis and systemic lupus erythematosus: a meta-analysis

STAT4 is a transcription factor that has been implicated in the pathogenesis of rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Recently, several reports has documented that a STAT4 haplotype is associated with RA, SLE and Sjogren's syndrome. To summarize and review these findings, we conducted a meta-analysis of all relevant reports published before September 2008. Studies on STAT4 rs7574865 single nucleotide polymorphism (SNP) of RA and SLE were identified using PubMed. Meta-analyses were performed for 15,609 patients with RA and 15,793 controls from 14 published studies and for 2,478 patients with SLE and 5,058 controls from 8 published studies. Meta-odds ratios (ORs) and 95% confidence intervals (CIs) based on random effects models were calculated for all available studies. The overall ORs for the minor T allele of STAT4 rs7574865 SNP were 1.27 (95% CI 1.20-1.34) in RA and 1.57 (95% CI 1.44-1.71) in SLE. Asian controls have significantly higher allele frequency (32%) for the minor T allele of STAT4 rs7574865 SNP than population of European origin (22%), however, there was no significant difference of ORs for RA and SLE by ethnicity. No apparent effect of anti-CCP positivity was found in stratified analysis. The risk of STAT4 genotype for SLE was significantly higher than for RA in populations of European origin and Asian. The results of our meta-analysis demonstrated that STAT4 rs7574865 SNP is significantly associated with RA and SLE. In addition to specific alleles of HLA-DRB1, the minor T allele of STAT4 rs7574865 SNP is a common RA risk factor in populations of European origin and Asian.

Unraveling the genetics of complex diseases: susceptibility genes for rheumatoid arthritis and psoriasis

Talk of numerous genetic risk factors for rheumatoid arthritis (RA) and psoriasis has been percolating for years, but with the exception of the human leukocyte antigen (HLA) region, none have been definitively identified. Recently the results of multiple, well powered, genetic case-control studies have begun to appear providing convincing statistical evidence for at least ten non-HLA related risk genes or loci (C5/TRAF1, CD40, CTLA4, KIF5A/PIP4K2C, MMEL1/TNFRSF14, PADI4, PRKCQ, PTPN22, STAT4, and TNFAIP3/OLIG3) for RA and six (IL12B, IL13, IL23R, STAT2/IL23A, TNFAIP3, and TNIP1) for psoriasis. These initial, novel findings are beginning to shed light on the molecular pathways pertinent to the individual diseases and highlight the pleiotropic effects of several risk factors as well as the allelic heterogeneity underlying susceptibility to these and other autoimmune diseases.

Replication of recently identified systemic lupus erythematosus genetic associations: a case-control study

Introduction

We aimed to replicate association of newly identified systemic lupus erythematosus (SLE) loci.

Methods

We selected the most associated SNP in 10 SLE loci. These 10 SNPs were analysed in 1,579 patients with SLE and 1,726 controls of European origin by single-base extension. Comparison of allele frequencies between cases and controls was done with the Mantel–Haenszel approach to account for heterogeneity between sample collections.

Results

A previously controversial association with a SNP in the TYK2 gene was replicated (odds ratio (OR) = 0.79, P = 2.5 × 10-⁵), as well as association with the X chromosome MECP2 gene (OR = 1.26, P = 0.00085 in women), which had only been reported in a single study, and association with four other loci, 1q25.1 (OR = 0.81, P = 0.0001), PXK (OR = 1.19, P = 0.0038), BANK1 (OR = 0.83, P = 0.006) and KIAA1542 (OR = 0.84, P = 0.001), which have been identified in a genome-wide association study, but not found in any other study. All these replications showed the same disease-associated allele as originally reported. No association was found with the LY9 SNP, which had been reported in a single study.

Conclusions

Our results confirm nine SLE loci. For six of them, TYK2, MECP2, 1q25.1, PXK, BANK1 and KIAA1542, this replication is important. The other three loci, ITGAM, STAT4 and C8orf13-BLK, were already clearly confirmed. Our results also suggest that MECP2 association has no influence in the sex bias of SLE, contrary to what has been proposed. In addition, none of the other associations seems important in this respect.

Association of CD40 with rheumatoid arthritis confirmed in a large UK case-control study

OBJECTIVE

A recent meta-analysis of published genome-wide association studies (GWAS) in populations of European descent reported novel associations of markers mapping to the CD40, CCL21 and CDK6 genes with rheumatoid arthritis (RA) susceptibility while a large-scale, case-control association study in a Japanese population identified association with multiple single nucleotide polymorphisms (SNPs) in the CD244 gene. The aim of the current study was to validate these potential RA susceptibility markers in a UK population.

METHODS

A total of 4 SNPs (rs4810485 in CD40, rs2812378 in CCL21, rs42041 in CDK6 and rs6682654 in CD244) were genotyped in a UK cohort comprising 3962 UK patients with RA and 3531 healthy controls using the Sequenom iPlex platform. Genotype counts in patients and controls were analysed with the chi(2) test using Stata.

RESULTS

Association to the CD40 gene was robustly replicated (p=2 x 10(-4), OR 0.86, 95% CI 0.79 to 0.93) and modest evidence was found for association with the CCL21 locus (p=0.04, OR 1.08, 95% CI 1.01 to 1.16). However, there was no evidence for association of rs42041 (CDK6) and rs6682654 (CD244) with RA susceptibility in this UK population. Following a meta-analysis including the original data, association to CD40 was confirmed (p=7.8 x 10(-8), OR 0.87 (95% CI 0.83 to 0.92).

CONCLUSION

In this large UK cohort, strong association of the CD40 gene with susceptibility to RA was found, and weaker evidence for association with RA in the CCL21 locus.

The genetics and epigenetics of autoimmune diseases

Self tolerance loss is fundamental to autoimmunity. While understanding of immune regulation is expanding rapidly, the mechanisms causing loss of tolerance in most autoimmune diseases remain elusive. Autoimmunity is believed to develop when genetically predisposed individuals encounter environmental agents that trigger the disease. Recent advances in the genetic and environmental contributions to autoimmunity suggest that interactions between genetic elements and epigenetic changes caused by environmental agents may be responsible for inducing autoimmune disease. Genetic loci predisposing to autoimmunity are being identified through multi-center consortiums, and the number of validated genes is growing rapidly. Recent reports also indicate that the environment can contribute to autoimmunity by modifying gene expression through epigenetic mechanisms. This article will review current understanding of the genetics and epigenetics of lupus, rheumatoid arthritis, multiple sclerosis and type 1 diabetes, using systemic lupus erythematosus as the primary example. Other autoimmune diseases may have a similar foundation.

Population differences in SLE susceptibility genes: STAT4 and BLK, but not PXK, are associated with systemic lupus erythematosus in Hong Kong Chinese

In this study, we compared the association of several newly discovered susceptibility genes for systemic lupus erythematosus (SLE) between populations of European origin and two Asian populations. Using 910 SLE patients and 1440 healthy controls from Chinese living in Hong Kong, and 278 SLE patients and 383 controls in Thailand, we studied association of STAT4, BLK and PXK with the disease. Our data confirmed association of STAT4 (rs7574865, odds ratio (OR) =1.71, P=3.55 x 10(-23)) and BLK (rs13277113, OR=0.77, P=1.34 x 10(-5)) with SLE. It was showed that rs7574865 of STAT4 is also linked to hematologic disorders and potentially some other subphenotypes of the disease. More than one genetic variant in STAT4 were found to be associated with the disease independently in our populations (rs7601754, OR=0.59, P=1.39 x 10(-9), and P=0.00034 when controlling the effect of rs7574865). With the same set of samples, however, our study did not detect any significant disease association for PXK, a risk factor for populations of European origin (rs6445975, joint P=0.36, OR=1.06, 95% confidence interval: 0.93-1.21). Our study indicates that some of the susceptibility genes for this disease may be population specific.

Recent advances in the genetics of autoimmune disease

Extraordinary technical advances in the field of human genetics over the past few years have catalyzed an explosion of new information about the genetics of human autoimmunity. In particular, the ability to scan the entire genome for common polymorphisms that associate with disease has led to the identification of numerous new risk genes involved in autoimmune phenotypes. Several themes are emerging. Autoimmune disorders have a complex genetic basis; multiple genes contribute to disease risk, each with generally modest effects independently. In addition, it is now clear that common genes underlie multiple autoimmune disorders. There is also heterogeneity among subphenotypes within a disease and across major racial groups. The current crop of genetic associations are only the start of a complete catalog of genetic factors for autoimmunity, and it remains unclear to what extent common variation versus multiple rare variants contribute to disease susceptibility. The current review focuses on recent discoveries within functionally related groups of genes that provide clues to novel pathways of pathogenesis for human autoimmunity.

Analysis of East Asia genetic substructure using genome-wide SNP arrays

Accounting for population genetic substructure is important in reducing type 1 errors in genetic studies of complex disease. As efforts to understand complex genetic disease are expanded to different continental populations the understanding of genetic substructure within these continents will be useful in design and execution of association tests. In this study, population differentiation (Fst) and Principal Components Analyses (PCA) are examined using >200 K genotypes from multiple populations of East Asian ancestry. The population groups included those from the Human Genome Diversity Panel [Cambodian, Yi, Daur, Mongolian, Lahu, Dai, Hezhen, Miaozu, Naxi, Oroqen, She, Tu, Tujia, Naxi, Xibo, and Yakut], HapMap [ Han Chinese (CHB) and Japanese (JPT)], and East Asian or East Asian American subjects of Vietnamese, Korean, Filipino and Chinese ancestry. Paired Fst (Wei and Cockerham) showed close relationships between CHB and several large East Asian population groups (CHB/Korean, 0.0019; CHB/JPT, 00651; CHB/Vietnamese, 0.0065) with larger separation with Filipino (CHB/Filipino, 0.014). Low levels of differentiation were also observed between Dai and Vietnamese (0.0045) and between Vietnamese and Cambodian (0.0062). Similarly, small Fst's were observed among different presumed Han Chinese populations originating in different regions of mainland of China and Taiwan (Fst's <0.0025 with CHB). For PCA, the first two PC's showed a pattern of relationships that closely followed the geographic distribution of the different East Asian populations. PCA showed substructure both between different East Asian groups and within the Han Chinese population. These studies have also identified a subset of East Asian substructure ancestry informative markers (EASTASAIMS) that may be useful for future complex genetic disease association studies in reducing type 1 errors and in identifying homogeneous groups that may increase the power of such studies.

Rheumatoid arthritis: a view of the current genetic landscape

The field of genetics and autoimmune diseases is undergoing a rapid and unprecedented expansion with new genetic findings being reported at an astounding pace. It is now clear that multiple genes contribute to each of the major autoimmune disorders, with significant genetic overlaps among them. Rheumatoid arthritis (RA) is no exception to this, and emerging data are beginning to reveal the outlines of new diagnostic subgroups, complex overlapping relationships with other autoimmune disorders and potential new targets for therapy. This review describes the evolving genetic landscape of RA, with the full knowledge that our current view is far from complete. However, with the first round of genome-wide association scans now completed, it is reasonable to begin to take stock of the direction in which the major common genetic risk factors are leading us.

Role of STAT4 polymorphisms in systemic lupus erythematosus in a Japanese population: a case-control association study of the STAT1-STAT4 region

Introduction

Recent studies identified STAT4 (signal transducers and activators of transcription-4) as a susceptibility gene for systemic lupus erythematosus (SLE). STAT1 is encoded adjacently to STAT4 on 2q32.2-q32.3, upregulated in peripheral blood mononuclear cells from SLE patients, and functionally relevant to SLE. This study was conducted to test whether STAT4 is associated with SLE in a Japanese population also, to identify the risk haplotype, and to examine the potential genetic contribution of STAT1. To accomplish these aims, we carried out a comprehensive association analysis of 52 tag single nucleotide polymorphisms (SNPs) encompassing the STAT1-STAT4 region.

Methods

In the first screening, 52 tag SNPs were selected based on HapMap Phase II JPT (Japanese in Tokyo, Japan) data, and case-control association analysis was carried out on 105 Japanese female patients with SLE and 102 female controls. For associated SNPs, additional cases and controls were genotyped and association was analyzed using 308 SLE patients and 306 controls. Estimation of haplotype frequencies and an association study using the permutation test were performed with Haploview version 4.0 software. Population attributable risk percentage was estimated to compare the epidemiological significance of the risk genotype among populations.

Results

In the first screening, rs7574865, rs11889341, and rs10168266 in STAT4 were most significantly associated (P < 0.01). Significant association was not observed for STAT1. Subsequent association studies of the three SNPs using 308 SLE patients and 306 controls confirmed a strong association of the rs7574865T allele (SLE patients: 46.3%, controls: 33.5%, P = 4.9 × 10^-6, odds ratio 1.71) as well as TTT haplotype (rs10168266/rs11889341/rs7574865) (P = 1.5 × 10^-6). The association was stronger in subgroups of SLE with nephritis and anti-double-stranded DNA antibodies. Population attributable risk percentage was estimated to be higher in the Japanese population (40.2%) than in Americans of European descent (19.5%).

Conclusions

The same STAT4 risk allele is associated with SLE in Caucasian and Japanese populations. Evidence for a role of STAT1 in genetic susceptibility to SLE was not detected. The contribution of STAT4 for the genetic background of SLE may be greater in the Japanese population than in Americans of European descent.

Molecular aspects of rheumatoid arthritis: role of transcription factors

Rheumatoid arthritis is a multifactorial disease characterized by chronic inflammation of the joints. Both genetic and environmental factors are involved in the pathogenesis leading to joint destruction and ultimately disability. In the inflamed RA joint the synovium is highly infiltrated by CD4+ T cells, B cells and macrophages, and the intimal lining becomes hyperplastic owing to the increased number of macrophage-like and fibroblast-like synoviocytes. This hyperplastic intimal synovial lining forms an aggressive front, called pannus, which invades cartilage and bone structures, leading to the destruction and compromised function of affected joints. This process is mediated by a number of cytokines (tumor necrosis factor-alpha, interleukin-1, interleukin-6, interleukin-17 interferon-gamma, etc.), chemokines (monocyte chemoattractant protein-1, monocyte chemoattractant protein-4 CCL18, etc.), cell adhesion molecules (intercellular adhesion molecule-1, vascular cell adhesion molecule-1, etc.) and matrix metalloproteinases. Expression of these molecules is controlled at the transcription level and activation of a limited number of transcription factors is involved in this process.