Variants within STAT genes reveal association with anticitrullinated protein antibody-negative rheumatoid arthritis in 2 European populations

ACPA-negative rheumatoid arthritis: From immune mechanisms to clinical translation

The presence of anti-citrullinated protein autoantibodies (ACPA) is a hallmark feature of rheumatoid arthritis (RA), which causes chronic joint destruction and systemic inflammation. Based on ACPA status, RA patients can be sub-grouped into two major subsets: ACPA-positive RA (ACPA⁺ RA) and ACPA-negative RA (ACPA^– RA). Accumulating evidence have suggested that ACPA⁺ RA and ACPA^– RA are two distinct disease entities with different underlying pathophysiology. In contrast to the well-characterized pathogenic mechanisms of ACPA⁺ RA, the etiology of ACPA^– RA remains largely unknown. In this review, we summarized current knowledge about the primary drivers of ACPA^– RA, particularly focusing on the serological, cellular, and molecular aspects of immune mechanisms. A better understanding of the immunopathogenesis in ACPA^– RA will help in designing more precisely targeting strategies, and paving the road to personalized treatment. In addition, identification of novel biomarkers in ACPA^– RA will substantially promote early treatment and improve the outcomes.

Association Between STAT4 rs7574865 Polymorphism and Rheumatoid Arthritis: Debate Unresolved

Background:

STAT4 rs7574865 polymorphism has been evidently associated with susceptibility to Rheumatoid Arthritis (RA) in European and Eastern Asian populations, whereas studies in other countries reported otherwise.

Objective:

We investigated the distribution of STAT4 rs7574865 polymorphism in a group of Syrian RA patients.

Methods:

Eighty-one RA patients and forty healthy controls were enrolled and STAT4 rs7574865 was genotyped by direct sequencing. RA patients were stratified according to Anti-Citrullinated Protein Antibodies (ACPA) status for analysis.

Results:

Minor T allele frequencies were 30.4%, 16.7%, and 23.8% in ACPA-positive RA patients, ACPA-negative RA patients, and healthy controls, respectively. No significant differences in STAT4 rs7574865 allele/genotype frequencies were found between ACPA-positive RA patients, ACPA-negative RA patients, and healthy controls (P>0.05).

Conclusion:

STAT4 rs7574865 TT genotype showed a potential impact on ACPA positivity in Syrian RA patients. However, STAT4 rs7574865 effect on RA onset and severity is minor compared to other genetic factors such as HLA-DRB1 shared epitope alleles.

Lack of significant association between selected STAT3 polymorphisms and rheumatoid arthritis in the Polish population

OBJECTIVES

Rheumatoid arthritis (RA) is the most common systemic inflammatory disease and is of unknown etiology. The altered balance between immunosuppressive and inflammatory T cell subpopulations exerts a huge impact on RA pathogenesis. The STAT3 protein regulates genes involved in the immune responses. It regulates maturation of T and B cells. Its abnormal activity is significantly associated with autoimmune diseases and cancer development. We aimed to evaluate the contribution of three potentially functional single nucleotide polymorphisms (SNPs) within the STAT3 gene to susceptibility and severity of RA in the Polish population.

MATERIAL AND METHODS

A total of 595 patients with RA and 330 healthy individuals were included in the study. DNA from patients and healthy subjects was obtained from peripheral blood using standard DNA isolating methods. The STAT3 rs1053005, rs1026916 and rs2293152 polymorphisms were genotyped using the TaqMan SNP genotyping assay. The accuracy of SNP genotyping was confirmed using direct DNA sequence analysis.

RESULTS

The distribution of STAT3 polymorphisms did not differ significantly between cases and controls. Our results revealed a tendency only, where rs1026916 AA genotype occurred more frequently in RA patients compared to healthy controls, in codominant (p = 0.09), dominant (p = 0.06) and recessive (p = 0.09) models. STAT3 rs2293152 polymorphism was associated with higher DAS28 (p = 0.014 codominant model; p = 0.003 dominant model), increased number of swollen joints (p = 0.02), higher VAS (p = 0.01) and higher HAQ score (p = 0.05).

CONCLUSIONS

We did not observe a significant association between the three studied STAT3 genetic variants and increased susceptibility to or severity of RA. Only the STAT3 rs2293152 polymorphism was associated with parameters that indicate a more severe course of the disease. However, its distribution did not differ between RA and control groups. According to our observations these 3 studied STAT3 SNPs may not be used as risk factors for developing RA.

Tocilizumab treatment leads to improvement in disease activity regardless of CCP status in rheumatoid arthritis

OBJECTIVE

Autoantibodies can be useful in predicting response to certain treatments in rheumatoid arthritis (RA). We aimed to evaluate initial response to tocilizumab (TCZ) by change in physician and patient-reported outcomes and laboratory parameters in a real-world cohort of patients with RA. We analyzed the data by autoantibody status to determine whether patients with seronegative RA had improved response to tocilizumab when compared to their seropositive counterparts.

METHODS

Data from the CORRONA RA registry were analyzed. Patients were included if they were started on TCZ and had data from a follow-up visit 4-8 months after initiation, as well as having information on serologic status. Serologic status was determined by presence of anti-cyclic citrullinated peptide (CCP) antibodies. Changes in disease activity measures from baseline to follow-up visit were evaluated.

RESULTS

Both CCP-negative and -positive groups had statistically significant improvement in physician-reported measurements (physician rating of disease activity and joint counts), patient-reported measures (disease activity, pain, and fatigue), and acute phase reactants after 4-8 months of treatment with tocilizumab. The magnitude of improvement, however, did not differ significantly by CCP status.

CONCLUSION

Tocilizumab led to statistically significant improvement in all patient- and physician-reported measures of disease activity evaluated in this cohort of patient with RA. The response to tocilizumab did not differ by CCP status.

Polymorphisms in STAT-4, IL-10, PSORS1C1, PTPN2 and MIR146A genes are associated differently with prognostic factors in Italian patients affected by rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease resulting in chronic inflammation of the synovium and consequent cartilage and bone erosion. RA is associated strongly with the presence of rheumatoid factor (RF), and consists of clinical subsets of anti-citrullinated protein antibody (ACPA)-positive and -negative patients. This study was designed to evaluate whether relevant single nucleotide polymorphisms (SNPs) associated with RA and other autoimmune disorders are related to RF, ACPA and clinical phenotype in a cohort of biologic drugs naive Italian RA patients; 192 RA patients and 278 age-matched healthy controls were included. Clinical and laboratory data were registered. We analysed a total of 12 single nucleotide polymorphisms (SNPs) in signal transducer and activator of transcription-4 (STAT-4), interleukin (IL)-10, psoriasis susceptibility 1 candidate 1 (PSORS1C1), protein tyrosine phosphatase, non-receptor type 2 (PTPN2), endoplasmic reticulum aminopeptidase 1 (ERAP1), tumour necrosis factor receptor-associated 3 interacting protein 2 (TRAF3IP2) and microRNA 146a (MIR146A) genes by allelic discrimination assays. Case-control association studies and genotype/phenotype correlation analyses were performed. A higher risk to develop RA was observed for rs7574865 in the STAT-4 gene, while the rs1800872 in the IL-10 gene showed a protective effect. The presence of RF was associated significantly with rs1800872 variant in IL-10, while rs2910164 in MIR146A was protective. ACPA were associated significantly with rs7574865 in STAT-4. The SNP rs2233945 in the PSORS1C1 gene was protective regarding the presence of bone erosions, while rs2542151 in PTPN2 gene was associated with joint damage. Our results confirm that polymorphisms in STAT-4 and IL-10 genes confer susceptibility to RA. For the first time, we described that SNPs in PSORS1C1, PTPN2 and MIR146A genes were associated differently with a severe disease phenotype in terms of autoantibody status and radiographic damage in an Italian RA population.

STAT4 rs7574865 G/T polymorphism is associated with rheumatoid arthritis and disease activity, but not with anti-CCP antibody levels in a Mexican population

Rheumatoid arthritis (RA) is a systemic autoimmune disease in whose etiology genetic factors are known to play an important role. Among the genes associated with RA, STAT4 could be an important factor in conducting helper T cells toward the pro-inflammatory Th1 and Th17 lineages. The aim of this study is to determine the association of the STAT4 polymorphism rs7574865 with RA, disease activity, and anti-cyclic citrullinated peptide (CCP) antibody levels in a Mexican population. Genotyping was carried out using the Taqman® system from Applied Biosystems in 140 patients with RA and 150 healthy subjects. Disease activity was evaluated by a rheumatologist using the DAS28 and Spanish-HAQ-DI instruments. Anti-CCP levels were determined by ELISA. Associations of the genotypes of rs7574865 with DAS28, HAQ, and anti-CCP antibody levels with RA were determined. Findings showed that the GT and TT genotypes and the T allele from rs7574865 were all associated as risk factors for RA, independently of their anti-CCP status. An association with moderate-to-high disease activity (DAS28 ≥ 3.2) was also found. Additionally, patients with the GT or TT genotypes showed lower HAQ values than those who carried the GG genotype. No differences in anti-CCP antibody levels or DAS28 and genotypes were found. This work supports the association of the STAT4 rs7574865 polymorphism with RA and disease activity, but not with anti-CCP antibody levels in a Mexican population.

The Ying and Yang of STAT3 in Human Disease

The transcription factor signal transducer and activator of transcription 3 (STAT3) is a critical regulator of multiple, diverse cellular processes. Heterozgyous, germline, loss-of-function mutations in STAT3 lead to the primary immune deficiency Hyper-IgE syndrome. Heterozygous, somatic, gain-of-function mutations in STAT3 have been reported in malignancy. Recently, germline, heterozygous mutations in STAT3 that confer a gain-of-function have been discovered and result in early-onset, multi-organ autoimmunity. This review summarizes what is known about the role of STAT3 in human disease.

Association of PTPN22 rs2476601 and STAT4 rs7574865 polymorphisms with rheumatoid arthritis: A meta-analysis update

BACKGROUND

Rheumatoid arthritis (RA) is a common autoimmune disease with a complex genetic background. The genes encoding protein tyrosine phosphatase non-receptor type 22 (PTPN22) and signal transducer and activator of transcription 4 (STAT4) have been reported to be associated with RA in several ethnic populations.

OBJECTIVES

This work aims to assess the association between PTPN22 rs2476601 and STAT4 rs7574865 polymorphisms with RA susceptibility through an updated meta-analysis of available case-control studies.

METHODS

A literature search of all relevant studies published from January 2007 up to December 2014 was conducted using Pubmed and Science Direct databases. The observed studies that were related to an association between PTPN22 rs2476601 and STAT4 rs7574865 polymorphisms with RA susceptibility were identified. Meta-analysis of the pooled and stratified data was done and assessed using varied genetic models.

RESULTS

Thirty-seven case-control studies with a total of 47 comparisons (29 for PTPN22 rs2476601 polymorphism and 18 for STAT4 rs7574865 polymorphism) met our inclusion criteria. The meta-analysis showed an association between PTPN22 T allele, CT+TT and TT genotypes with RA susceptibility. Furthermore, The meta-analysis showed an association between STAT4 T allele, GT+TT and TT genotypes with RA susceptibility. Stratification of RA patients according to ethnic groups showed that PTPN22 T allele, CT+TT genotypes, STAT4 T allele and STAT4 GT+TT were significantly associated with RA in European, Asian, African subjects, while PTPN22 TT genotype was significantly associated with RA in European but not in Asian and African subjects and STAT4 TT genotype was significantly associated with RA in European and Asian but not in African subject. A subgroup analysis according to the presence or absence of rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) antibodies revealed that the association between PTPN22 rs2476601 and STAT4 rs7574865 polymorphisms with RA susceptibility may not be dependent on RF and anti-CCP antibodies.

CONCLUSIONS

Our meta-analysis demonstrated that PTPN22 rs2476601 and STAT4 rs7574865 polymorphisms confers susceptibility to RA in total subjects and in major ethnic groups. The association may not be dependent on RF and anti-CCP antibodies.

STAT1 single nucleotide polymorphisms and susceptibility to immune thrombocytopenia

Primary immune thrombocytopenia (ITP) is an acquired autoimmune bleeding disorder. One of the key mediators of IFN-γ signaling is the signal transducer and activator of transcription 1 protein (STAT1). We evaluated the relationship between STAT1 gene single nucleotide polymorphisms (SNPs) and the associated risk of ITP in a prospective case-control study. A total of 548 children were recruited: 328 children with ITP and 220 healthy children as sex- and age-matched normal controls. The Sequenom MassArray system (Sequenom, San Diego, CA) was used to detect three SNPs genotypes in the STAT1 gene: rs10208033, rs12693591, and rs1467199. There is a statistically significant difference in STAT1 rs1467199 allele frequencies with comparison of each of the four clinical subgroups of ITP patients to the normal controls (p = 0.0432). Also, newly diagnosed ITP patients and chronic ITP patients demonstrate significant different genotypes (χ(2 )= 8.511, p = 0.0142) and allelic frequency (p = 0.0055). Although a positive STAT1 rs1467199 genotype subgroups to the STAT1 mRNA expression level cannot be established, there is a weak correlation between STAT1 mRNA level and the activity ratio of Type 1 T helper lymphocyte and Type 2 T helper lymphocyte (Th1/Th2 ratio) (p = 0.0544); correlation with IFN-γ alone did not reach statistical significance (p = 0.1715). The findings in our study suggest that STAT1 rs1467199 SNP plays a potential role in the IFN-γ dependent development of autoimmunity in children with ITP. The important clinical implication of STAT1 SNPs testing as a predictor of pediatric chronic ITP will be validated in future molecular and protein functional analysis.

IL-6-driven STAT signalling in circulating CD4+ lymphocytes is a marker for early anticitrullinated peptide antibody-negative rheumatoid arthritis

Objectives

A previously identified signal transduction and activator of transcription-3 (STAT3) target-enriched gene signature in circulating CD4+ T cells of patients with early rheumatoid arthritis (RA) was prominent in autoantibody-negative individuals. Here, interleukin (IL)-6-mediated STAT signalling was investigated in circulating lymphocytes of an independent early arthritis patient cohort, seeking further insight into RA pathogenesis and biomarkers of potential clinical utility.

Methods

Constitutive and IL-6-induced expression of phosphorylated STAT1 (pSTAT1) and pSTAT3 was determined in T and B cells using Phosflow cytometric analysis in patients with RA and controls. Contemporaneous levels of serum cytokines were measured by immunoassay. Induced gene expression was measured in cultured CD4+T cells by quantitative real-time PCR.

Results

Among circulating lymphocytes of 187 patients with early arthritis, constitutive pSTAT3 correlated with serum IL-6 levels maximally in CD4+ T cells. Increased constitutive pSTAT3, but not pSTAT1, was observed in circulating CD4+ T cells of patients with early anticitrullinated peptide autoantibody (ACPA)-negative RA compared with disease controls, and these levels decreased alongside markers of disease activity with IL-6R-targeted treatment. Among patients presenting with seronegative undifferentiated arthritis (UA) the ratio of constitutive pSTAT3:pSTAT1 in CD4+ T cells contributed substantially to an algorithm for predicting progression to classifiable RA during a median of 20 months follow-up (area under receiver operator characteristic curve=0.84; p<0.001).

Conclusions

Our findings support a particular role for IL-6-driven CD4+ T cell activation via STAT3 during the induction of RA, particularly as a feature of ACPA-negative disease. CD4+ T cell pSTAT measurements show promise as biomarkers of UA–RA progression and now require independent validation.

Type I IFNs as biomarkers in rheumatoid arthritis: towards disease profiling and personalized medicine

RA (rheumatoid arthritis) is a chronic rheumatic condition hallmarked by joint inflammation and destruction by self-reactive immune responses. Clinical management of RA patients is often hampered by its heterogeneous nature in both clinical presentation and outcome, thereby highlighting the need for new predictive biomarkers. In this sense, several studies have recently revealed a role for type I IFNs (interferons), mainly IFNα, in the pathogenesis of a subset of RA patients. Genetic variants associated with the type I IFN pathway have been linked with RA development, as well as with clinical features. Moreover, a role for IFNα as a trigger for RA development has also been described. Additionally, a type I IFN signature has been associated with the early diagnosis of RA and clinical outcome prediction in patients undergoing biological drug treatment, two challenging issues for decision-making in the clinical setting. Moreover, these cytokines have been related to endothelial damage and vascular repair failure in different autoimmune disorders. Therefore, together with chronic inflammation and disease features, they could probably account for the increased cardiovascular disease morbidity and mortality of these patients. The main aim of the present review is to provide recent evidence supporting a role for type I IFNs in the immunopathology of RA, as well as to analyse their possible role as biomarkers for disease management.

Seronegative rheumatoid arthritis: pathogenetic and therapeutic aspects

Rheumatoid arthritis (RA) has long been recognised as a highly heterogeneous disease of immune dysregulation. Despite an ever-growing appreciation of the role of circulating autoantibodies in the development of 'seropositive' disease, the pathogenesis of seronegative RA remains poorly understood. Accumulating evidence suggests that RA 'serotypes', in fact, reflect distinct disease entities that, despite their clinical overlap, diverge in respect of genetic architecture, cellular pathology and even therapeutic responsiveness. Focussing on seronegative RA, this review considers these concepts and their implications for the management of patients with this challenging, though sometimes overlooked, condition.

Prognosis of seronegative patients in a large prospective cohort of patients with early inflammatory arthritis

OBJECTIVE

Rheumatoid factor (RF) and anticitrullinated protein antibodies (ACPA) are believed to be associated with more severe rheumatoid arthritis; however, studies in early inflammatory arthritis (EIA) have yielded conflicting results. Our study determined the prognosis of baseline ACPA-negative and RF-negative patients.

METHODS

Patients enrolled in the Canadian Early Arthritis Cohort had IgM RF and IgG anticyclic citrullinated peptide antibodies 2 (anti-CCP2) measured at baseline. Remission was defined as a Disease Activity Score of 28 joints (DAS28) < 2.6 using logistic regression accounting for confounders at 12-month and 24-month followup.

RESULTS

Of the 841 patients, 216 (26%) were negative for both RF and anti-CCP2. Compared to seropositive subjects, seronegative subjects were older (57 ± 15 vs 51 ± 14 yrs), more males proportionately (31% vs 23%), and had shorter length of symptoms (166 ± 87 vs 192 ± 98 days), and at baseline had higher mean swollen joint count (SJC; 8.8 ± 6.8 vs 6.5 ± 5.6), DAS28 (5.0 ± 1.6 vs 4.8 ± 1.5), and erosive disease (32% vs 24%, p < 0.05). Treatment was similar between the 2 groups. At 24-month followup, seronegative compared to seropositive subjects had greater mean change (Δ ± SD) in disease activity measures: ΔSJC counts (-6.9 ± 7.0 vs -5.1 ± 5.9), ΔDAS28 (-2.4 ± 2.0 vs -1.8 ± 1.8), and ΔC-reactive protein (-11.0 ± 17.9 vs -6.4 ± 17.5, p < 0.05). Accounting for confounders, antibody status was not significantly associated with remission. However, at 12-month followup, ACPA-positive subjects were independently more likely to have new erosive disease (OR 2.94, 95% CI 1.45-5.94).

CONCLUSION

Although seronegative subjects with EIA have higher baseline DAS28 compared to seropositive subjects, they have a good response to treatment and are less likely to develop erosive disease during followup.

Activating germline mutations in STAT3 cause early-onset multi-organ autoimmune disease

Monogenic causes of autoimmunity provide key insights into the complex regulation of the immune system. We report a new monogenic cause of autoimmunity resulting from de novo germline activating STAT3 mutations in five individuals with a spectrum of early-onset autoimmune disease, including type 1 diabetes. These findings emphasize the critical role of STAT3 in autoimmune disease and contrast with the germline inactivating STAT3 mutations that result in hyper IgE syndrome.

Genome-wide association studies to advance our understanding of critical cell types and pathways in rheumatoid arthritis: recent findings and challenges

PURPOSE OF REVIEW

A significant number of loci implicated in rheumatoid arthritis (RA) susceptibility have been highlighted by genome-wide association studies (GWAS). Here, we review the recent advances of GWAS in understanding the genetic architecture of RA, and place these findings in the context of RA pathogenesis.

RECENT FINDINGS

Although the interpretation of GWAS findings in the context of the disease biology remains challenging, interesting observations can be highlighted. Integration of GWAS results with cell-type specific gene expression or epigenetic marks have highlighted regulatory T cells and CD4 memory T cells as critical cell types in RA. In addition, many genes in RA loci are involved in the nuclear factor-kappaB signaling pathway or the Janus kinase (JAK)-signal transducers and activators of transcription (STAT) signaling pathway. The observation that these pathways are targeted by several approved drugs used to treat the symptoms of RA highlights the promises of human genetics to provide insights in the disease biology, and help identify new therapeutic targets.

SUMMARY

These findings highlight the promises and need of future studies investigating causal genes and underlined mechanisms in GWAS loci to advance our understanding of RA.

Association between STAT4 gene polymorphisms and autoimmune thyroid diseases in a Chinese population

The STAT4 gene encodes a transcriptional factor that transmits signals induced by several key cytokines which play important roles in the development of autoimmune diseases. The aim of this study was to explore the association of STAT4 polymorphism with Graves’ disease (GD) and Hashimoto’s thyroiditis (HT). A total of 1048 autoimmune thyroid diseases (AITDs) patients (693 with GD and 355 with HT) and 909 age- and gender-matched controls were examined. STAT4 polymorphisms (rs7574865/rs10181656/rs7572482) were genotyped by multiplex polymerase chain reaction (PCR) and ligase detection reaction (LDR). The results indicated that the frequencies of rs7574865 genotypes in patients with GD differed significantly from the controls (p = 0.028), the T allele frequency of GD patients was also significantly higher than the controls (p = 0.020). The genotypes of rs10181656 differed significantly in GD patients from controls (p = 0.012); G allele frequencies were significantly higher in AITD patients than the controls (p = 0.014 and 0.031, respectively). The frequencies of haplotype GC with GD and HT patients were significantly lower than their controls (p = 0.015 and 0.030, respectively). In contrast, the frequencies of haplotype TG with GD and HT patients were significantly higher than their controls (p = 0.016 and 0.048, respectively). These findings strongly suggest that STAT4 rs7574865/rs10181656 polymorphisms increase the risk of AITD in a Chinese population.

HCV infection enhances Th17 commitment, which could affect the pathogenesis of autoimmune diseases

BACKGROUND

Various kinds of autoimmune diseases have been reported to have a significant relationship with persistent hepatitis c virus (HCV) infection and Th17 cells. Previously, our group reported that the existence of HCV in T lymphocytes could affect the development of CD4+ helper T cells and their proliferation, in addition to the induction of immunoglobulin hyper-mutation.

METHODS

Therefore, we analyzed the relationship between persistent infection of HCV and the mechanism of Th17 cell induction ex vivo and in vitro.

RESULTS

The prevalence of autoimmune-related diseases in chronic hepatitis c patients (CH-C) was significantly higher than in other types of chronic hepatitis (hepatitis B and NASH). A significantly higher frequency of IL6 and TGF-β double-high patients was detected in CH-C than in other liver diseases. Moreover, these double-high patients had significantly higher positivity of anti-nuclear antibody, cryoglobulinemia, and lymphotropic HCV and higher amounts of IL1-β, IL21, IL23. In addition to the previously reported lymphotropic SB-HCV strain, we found a novel, genotype 1b lymphotropic HCV (Ly-HCV), by deep sequencing analysis. Lymphotropic-HCV replication could be detected in the lymphoid cells with various kinds of cytokine-conditions including IL1β, IL23, IL6 and TGF-β in vitro. Infection by HCV could significantly enhance the development of Th17 cells. The HCV protein responsible for inducing the Th17 cells was HCV-Core protein, which could enhance the STAT-3 signaling and up-regulate the expression of RORγt as a Th17 master gene.

CONCLUSION

Infection by lymphotropic HCV might enhance the Th17 development and contribute to understanding the pathogenesis of autoimmune-related diseases.

Rs7574865 polymorphism in signal transducers and activators of transcription 4 gene and rheumatoid arthritis: an updated meta-analysis of 28 case-control comparisons

OBJECTIVES

The objective of the present meta-analysis was to investigate whether the combined evidence shows an association between the STAT4 rs7574865 polymorphism and RA.

METHODS

A systematic search of all relevant studies published through April 2013 was conducted using MEDLINE, EMBASE, OVID, and ScienceDirect. The observational studies that were related to an association between the STAT4 rs7574865 polymorphism and RA were identified. The association between the STAT4 rs7574865 polymorphism and RA susceptibility was assessed using genetic models.

RESULTS

Seventeen case-control studies with a total of 28 comparisons (25 300 RA patients and 26 326 controls) met the inclusion criteria. A meta-analysis was conducted for genotype TT versus GT+GG, GT+TT versus GG, TT versus GG and T-allele. The meta-analysis showed an association between RA and the STAT4 rs7574865 TT genotype, GT+TT genotype and T-allele in all subjects. Stratification of RA patients according to ethnic group showed that the TT genotype, GT+TT genotype and T-allele were significantly associated with RA in Europeans, Asians, Africans and Latin Americans. A subgroup analysis according to the absence or presence of rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) antibodies revealed that the association between the STAT4 rs7574865 polymorphism and RA may be independent of the presence of RF and anti-CCP antibodies.

CONCLUSIONS

This meta-analysis demonstrated that the STAT4 rs7574865 polymorphism confers susceptibility to RA in major ethnic groups. The association may not be dependent on the presence of RF and anti-CCP antibodies.

Identification of secreted phosphoprotein 1 gene as a new rheumatoid arthritis susceptibility gene

OBJECTIVE

To evaluate the contribution of the SPP1 rs11439060 and rs9138 polymorphisms, previously reported as autoimmune risk variants, in the rheumatoid arthritis (RA) genetic background according to anti-citrullinated protein antibodies (ACPAs) status of RA individuals.

METHODS

We analysed a total of 11,715 RA cases and 26,493 controls from nine independent cohorts; all individuals were genotyped or had imputed genotypes for SPP1 rs11439060 and rs9138. The effect of the SPP1 rs11439060 and rs9138 risk-allele combination on osteopontin (OPN) expression in macrophages and OPN serum levels was investigated.

RESULTS

We provide evidence for a distinct contribution of SPP1 to RA susceptibility according to ACPA status: the combination of ≥3 SPP1 rs11439060 and rs9138 common alleles was associated mainly with ACPA negativity (p=1.29×10(-5), ORACPA-negative 1.257 (1.135 to 1.394)) and less with ACPA positivity (p=0.0148, ORACPA-positive 1.072 (1.014 to 1.134)). The ORs between these subgroups (ie, ACPA-positive and ACPA-negative) significantly differed (p=7.33×10(-3)). Expression quantitative trait locus analysis revealed an association of the SPP1 risk-allele combination with decreased SPP1 expression in peripheral macrophages from 599 individuals. To corroborate these findings, we found an association of the SPP1 risk-allele combination and low serum level of secreted OPN (p=0.0157), as well as serum level of secreted OPN correlated positively with ACPA production (p=0.005; r=0.483).

CONCLUSIONS

We demonstrate a significant contribution of the combination of SPP1 rs11439060 and rs9138 frequent alleles to risk of RA, the magnitude of the association being greater in patients negative for ACPAs.

Transcription factor STAT1 gene polymorphism is associated with the development of severe forms of periodontal disease

INTRODUCTION

Periodontal disease (PD) is one of the most common inflammatory diseases, affecting about 10 % of the world population. The establishment of PD is influenced by polymorphisms in genes involved with the inflammatory response. Signal Transducer and Activator of Transcription (STAT)-1 is a transcription factor that plays a key role in the intracellular signaling triggered by cytokines and, thus, its activation is critical in inflammatory diseases.

AIM AND METHODS

We aim to evaluate the occurrence of association between STAT-1 (rs3771300) polymorphism and distinct clinical forms and severity of PD; we genotyped 180 subjects using realtime PCR.

RESULTS AND CONCLUSION

We observed that the presence of the G allele for STAT-1 was associated with twice as high of a chance to develop aggressive periodontitis, and the most severe form of the disease.

A systems biology-based investigation into the pharmacological mechanisms of wu tou tang acting on rheumatoid arthritis by integrating network analysis

Aim. To investigate pharmacological mechanisms of Wu Tou Tang acting on rheumatoid arthritis (RA) by integrating network analysis at a system level. Methods and Results. Drug similarity search tool in Therapeutic Targets Database was used to screen 153 drugs with similar structures to compositive compounds of each ingredient in Wu Tou Tang and to identify 56 known targets of these similar drugs as predicted molecules which Wu Tou Tang affects. The recall, precision, accuracy, and F1-score, which were calculated to evaluate the performance of this method, were, respectively, 0.98, 0.61, 59.67%, and 0.76. Then, the predicted effector molecules of Wu Tou Tang were significantly enriched in neuroactive ligand-receptor interaction and calcium signaling pathway. Next, the importance of these predicted effector molecules was evaluated by analyzing their network topological features, such as degree, betweenness, and k-coreness. We further elucidated the biological significance of nine major candidate effector molecules of Wu Tou Tang for RA therapy and validated their associations with compositive compounds in Wu Tou Tang by the molecular docking simulation. Conclusion. Our data suggest the potential pharmacological mechanisms of Wu Tou Tang acting on RA by combining the strategies of systems biology and network pharmacology.

Ultrasonographic assessment of enthesitis in HLA-B27 positive patients with rheumatoid arthritis, a matched case-only study

Introduction

HLA-B27 has a modifier effect on the phenotype of multiple diseases, both associated and non-associated with it. Among these effects, an increased frequency of clinical enthesitis in patients with Rheumatoid Arthritis (RA) has been reported but never explored again. We aimed to replicate this study with a sensitive and quantitative assessment of enthesitis by using standardized ultrasonography (US).

Methods

The Madrid Sonography Enthesitis Index (MASEI) was applied to the US assessment of 41 HLA-B27 positive and 41 matched HLA-B27 negative patients with longstanding RA. Clinical characteristics including explorations aimed to evaluate spondyloarthrtitis and laboratory tests were also done.

Results

A significant degree of abnormalities in the entheses of the patients with RA were found, but the MASEI values, and each of its components including the Doppler signal, were similar in HLA-B27 positive and negative patients. An increase of the MASEI scores with age was identified. Differences in two clinical features were found: a lower prevalence of rheumatoid factor and a more common story of low back pain in the HLA-B27 positive patients than in the negative. The latter was accompanied by radiographic sacroiliitis in two HLA-B27 positive patients. No other differences were detected.

Conclusion

We have found that HLA-B27 positive patients with RA do not have more enthesitis as assessed with US than the patients lacking this HLA allele. However, HLA-B27 could be shaping the RA phenotype towards RF seronegativity and axial involvement.