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

Association between CTLA-4 gene polymorphism and risk of rheumatoid arthritis: a meta-analysis

Cytotoxic T lymphocyte-associated protein 4 (CTLA-4) gene polymorphisms may be involved in the risk of Rheumatoid arthritis (RA). However, evidence for the association remains controversial. Therefore, we performed a meta-analysis to confirm the relationship between CTLA-4 gene polymorphisms and RA. The pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to assess the strength of association. Stratified analysis was conducted by ethnicity. In total, 66 case-control studies including 21681 cases and 23457 controls were obtained. For rs3087243 polymorphism, significant association was detected in Asians (A vs. G: OR=0.77, 95%CI=0.65-0.90, P=0.001; AA vs. GG: OR=0.67, 95%CI=0.48-0.94, P=0.02) and Caucasians (A vs. G: OR=0.89, 95%CI=0.86-0.93, P<0.00001; AA vs. GG: OR=0.81, 95%CI=0.75-0.88, P<0.00001). For rs231775 polymorphism, significant association was observed in the overall (G vs. A: OR =1.16, 95%CI=1.08-1.25, P<0.0001; GG vs. AA: OR=1.29, 95%CI=1.12-1.50, P=0.0006), and in Asians (G vs. A: OR=1.27, 95%CI=1.10-1.47, P=0.001; GG vs. AA: OR=1.58, 95%CI=1.24-2.01, P=0.0002), but not in Caucasians. However, there was no association between rs5742909 polymorphism and RA. This meta-analysis confirmed that rs3087243 and rs231775 polymorphism were associated with the risk of RA in both overall population and ethnic-specific analysis, but there was no association between rs5742909 polymorphism and RA risk.

Advances in the genomics of ANCA-associated vasculitis-a view from East Asia

Recent genome-wide association studies (GWAS) in populations of European ancestry have identified several susceptibility genes to anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). The most significant association was observed in HLA-DP variants in granulomatosis with polyangiitis and proteinase 3 (PR3)-ANCA positive vasculitis, while HLA-DQ variants were strongly associated with microscopic polyangiitis (MPA) and myeloperoxidase (MPO)-ANCA positive vasculitis (MPO-AAV). In non-HLA genes, SERPINA1, PRTN3 and PTPN22 were identified as susceptibility genes to AAV. The observations in GWAS suggested the presence of shared and non-shared susceptibility genes among AAV subsets. Epidemiological features of AAV are strikingly different in the East Asian populations; the proportions of MPO-AAV among total AAV, MPO-ANCA positive patients among GPA, and patients with interstitial lung disease among total AAV are considerably higher in Japan as compared with Europe. Such population differences suggest the critical role for genetic background behind these conditions. Although no GWAS has been reported in the Asian populations so far, the association of HLA-class II alleles with MPA and MPO-AAV was identified. Future genomics studies on AAV, especially from Asian populations, will provide valuable information to elucidate the molecular mechanisms and to identify molecular targets for AAV.

The pre-clinical phase of rheumatoid arthritis: From risk factors to prevention of arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease considered as a multistep process spanning from the interaction of genetic (e.g., shared epitope or non-HLA loci), environmental and behavioral risk factors (e.g., smoking) leading to breaking immune tolerance and autoimmune processes such as the production of autoantibodies (e.g., antibodies against citrullinated proteins ACPA or rheumatoid factors, RF), development of the first symptoms without clinical arthritis, and, finally, the manifestation of arthritis. Despite the typical joint involvement in established RA, the pathogenesis of the disease likely begins far from joint structures: in the lungs or periodontium in association with citrullination, intestinal microbiome, or adipose tissue, which supports normal findings in synovial tissue in ACPA+ patients with arthralgia. The presence of ACPA is detectable even years before the first manifestation of RA. The pre-clinical phase of RA is the period preceding clinically apparent RA with ACPA contributing to the symptoms without subclinical inflammation. While the combination of ACPA and RF increases the risk of progression to RA by up to 10 times, increasing numbers of novel autoantibodies are to be investigated to contribute to the increased risk and pathogenesis of RA. With growing knowledge about the course of RA, new aspiration emerges to cure and even prevent RA, shifting the "window of opportunity" to the pre-clinical phases of RA. The clinical definition of individuals at risk of developing RA (clinically suspect arthralgia, CSA) makes it possible to unify these at-risk individuals' clinical characteristics for "preventive" treatment in ongoing clinical trials using mostly biological or conventional synthetic disease-modifying drugs. However, the combination of symptoms, laboratory, and imaging biomarkers may be the best approach to select the correct target at-risk population. The current review aims to explore different phases of RA and discuss the potential of (non)pharmacological intervention aiming to prevent RA.

Plasma interleukin-21 levels and genetic variants are associated with susceptibility to rheumatoid arthritis

Background

Rheumatoid Arthritis (RA) is a chronic inflammatory condition characterized by autoantibodies development and an elevated spectrum of pro-inflammatory cytokines. Previous reports highlighted a relationship between IL-21and the pathogenesis of RA. Although elevated IL-21 levels have been reported in RA patients, the association of common IL-21 genetic variants with a predisposition to RA development in the Chinese population lacks.

Materials and methods

Five hundred and fourteen Chinese subjects (healthy controls: 303 and rheumatoid arthritis patients: 211) were enrolled in the study. Clinical data of patients were collected from medical records, and patients were treated as per the guidelines. Common single nucleotide polymorphisms in the IL-21 gene (rs907715, rs2221903, rs2055979 and rs6822844) were genotyped by TaqMan SNPs genotyping method. IL-21 level in plasma of RA patients and healthy subjects was measured by ELISA.

Results

The plasma level of IL-21 was significantly higher in subjects with rheumatoid arthritis relative to healthy controls (p < 0.0001). A positive correlation was observed between IL-21 level and DAS28 score, indicating the association of the cytokine with the worsening of the disease (Spearman r = 0.61, p < 0.0001). The prevalence of AA genotype (rs2055979) was significantly higher in RA subjects than in the controls (p < 0.0001, χ2 = 34.73, OR = 4.34, 95% CI = 2.623 to 7.219). Furthermore, elevated plasma IL-21 was observed in the rs2055979-AA genotype compared to CC type (p < 0.0001).

Conclusion

IL-21 plays a crucial function in rheumatoid arthritis pathogenesis. IL-21 rs2055979 polymorphism is associated with IL-21 plasma levels and is predisposed to RA development in the Chinese population.

The Association Between CTLA-4, CD80/86, and CD28 Gene Polymorphisms and Rheumatoid Arthritis: An Original Study and Meta-Analysis

Background: Rheumatoid arthritis (RA) is related to several pivotal susceptibility genes, including cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and costimulatory molecule (CD80/CD86) genes. Although the connection between polymorphisms of CTLA-4 and CD86 genes in different populations of RA have been studied extensively, the results are controversial. Objective: To clarify the correlation in the Chinese Han population between CTLA-4, CD80/86, and CD28 gene polymorphisms, and RA susceptibility. Methods: A case-control study (574 RA patients and 804 controls) was conducted to determine the correlation between CTLA-4 rs231775 and rs16840252 gene polymorphisms, CD86 rs17281995 gene polymorphisms, and the risk of RA for the Chinese Han population. Furthermore, an additional meta-analysis, including three single nucleotide polymorphisms (SNPs) (CTLA-4 rs231775, CTLA-4 rs3087243, and CTLA-4 rs5742909) from 32 citations, including 43 studies, 24,703 cases and 23,825 controls was performed to elucidate the relationship between known SNPs in the CTLA-4 genes and RA for more robust conclusions. Results: The results showed that CTLA-4 rs231775 gene polymorphism decreased the RA risk (GA vs. AA, OR = 0.77, P = 0.025), whereas CTLA-4 rs16840252 and CD86 rs17281995 gene polymorphisms were not related to RA susceptibility. Stratification analyses by RF, ACPA, CRP, ESR, DAS28, and functional class identified significant associations for CTLA-4 rs231775 and rs16840252 gene polymorphisms in the RF-positive and RF-negative groups. A meta-analysis of the literature on CTLA-4 gene polymorphisms and RA risk revealed that the risk of RA was decreased by CTLA-4 rs231775 gene polymorphisms. Conclusions: The CTLA-4 rs231775 gene polymorphism decreased the risk of RA, whereas CTLA-4 rs16840252 and CD86 rs17281995 gene polymorphisms were not related to RA risk. A meta-analysis indicated that CTLA-4 rs231775 and rs3087243 gene polymorphisms decreased the risk of RA. To support these analytical results, additional clinical cases should be investigated in further studies.

IL-21 gene rs6822844 polymorphism and rheumatoid arthritis susceptibility

Interleukin-21 (IL-21) is a cytokine that plays a crucial role in pathogenesis and activity of the rheumatoid arthritis (RA). Meanwhile, genetic polymorphisms in the IL-21 gene may alter its expression. Previous studies have reported conflicting results assessing the association between the IL-21 rs6822844 G/T polymorphism and RA risk. Thus, it's necessary to perform a meta-analysis to definite above relationship. PubMed database was searched for all papers published until October 20, 2019. Nine case-control studies with 9998 cases and 10742 controls were retrieved based on the search criteria at last. Odds ratio (95% confidence interval) was used to calculate the strength of this association. Publication bias was detected using both Begg's and Egger's tests. Overall, the IL-21 rs6822844 G/T polymorphism was found to be significantly associated with decreased RA risk (e.g. T-allele versus G-allele: OR = 0.81, 95% CI = 0.72-0.91, P < 0.001). In addition, decreased RA risk was also detected both in Asians (eg: TT+TG versus GG: OR = 0.42, 95% CI = 0.31-0.56, P < 0.001) and Caucasians (eg: TT+TG versus GG: OR = 0.85, 95% CI = 0.80-0.91, P < 0.001). A similar trend in association was found in the source of the control and genotype method subgroups. Furthermore, subgroup analysis of rheumatoid factor status revealed a protective relationship between the IL-21 rs6822844 G/T polymorphism and RF+/RF- RA risk. A similar relationship was noted in the anti-citrullinated protein antibody status subgroup. The results of the present study suggest that the IL-21 rs6822844 G/T polymorphism was significantly associated with decreased RA susceptibility.

Current and novel therapeutic targets in the treatment of rheumatoid arthritis

Rheumatoid arthritis (RA), a multifactorial disease characterized by synovitis, cartilage destruction, bone erosion, and periarticular decalcification, finally results in impairment of joint function. Both genetic and environmental factors are risk factors in the development of RA. Unwanted side effects accompany most of the current treatment strategies, and around 20-40% of patients with RA do not clinically benefit from these treatments. The unmet need for new treatment options for RA has prompted research in the development of novel agents acting through physiologically and pharmacologically relevant targets. Here we discuss in detail three critical pathways, Janus kinase/signal transducer and activator of transcription (JAK/STAT), Th17, and hypoxia-inducible factor (HIF), and their roles as unique therapeutic targets in the field of RA. Some of the less developed but potential targets like nucleotide-binding and oligomerization domain-like receptor containing protein 3 (NLRP3) inflammasome and histone deacetylase 1 (HDAC1) are also discussed.

IL-17, IL-21 and IL-22 polymorphisms in rheumatoid arthritis: A systematic review and meta-analysis

BACKGROUND

Rheumatoid Arthritis (RA) is an autoimmune systemic disease and in its pathogenesis participate several proinflammatory cytokines, including those produced by Th17 cells. We performed a systematic review aiming to assess the associations between polymorphisms in Th17 cytokines, namely IL-17A, IL-17F, IL-21 and IL-22, and susceptibility to RA.

METHODS

We searched three electronic databases (MEDLINE, Scopus and Web of Science) for observational studies assessing the association between susceptibility to RA (or its clinical presentation) and polymorphisms of the cytokines IL-17A, IL-17F, IL-21 and IL-22. From the selected studies, we extracted information on the studied polymorphisms, assessed outcomes, and demographic characteristics of participants. We performed random effects meta-analyses assessing the associations between susceptibility to RA and different genotypes of the IL-17A rs2275913, IL-17Frs763780 andIL-17Frs2397084polymorphisms. Primary studies' quality was assessed using the Q-Genie tool.

RESULTS

Fifteen studies were included in this systematic review. Five IL-17A polymorphisms were reported to be associated with susceptibility to RA. For the IL-17A rs2275913 polymorphism, our meta-analysis showed the AA genotype to be significantly associated with lower susceptibility to RA(OR = 0.76; 95%CI = 0.61-0.93;p = 0.01), while the opposite was observed for the GG genotype (OR = 1.20; 95%CI = 1.06-1.35;p = 0.01). Concerning IL-17Frs763780 polymorphism, theTT genotype was found to be significantly less frequent in RA patients(OR = 0.49; 95%CI = 0.31-0.77;p = 0.002), while the opposite was observed for the CT genotype (OR = 2.00; 95%CI = 1.03-3.87;p = 0.04). No significant associations were found regarding rs2397084polymorphisms. For IL-21, rs6822844 and rs4505848 were described to have significant associations with susceptibility to RA. No studies were found assessing IL-22 polymorphisms in RA.

CONCLUSIONS

IL-17A rs2275913 and IL-17F rs763780 polymorphisms are significantly associated with susceptibility to RA and with different clinical characteristics of this disease.

Association between interleukin-21 gene rs6822844 polymorphism and rheumatoid arthritis susceptibility

Controversial results concerning the association between a polymorphism rs6822844 in the interleukin (IL) 21 (IL-21) gene and rheumatoid arthritis (RA) have existed. A meta-analysis to confirm above relationships is necessary to be performed immediately. We conducted a search in the PubMed database, covering all papers published up to 20 October 2018. Overall, six case–control studies with 3244 cases and 3431 healthy controls were included. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of this association. Publication bias was assessed with both Egger’s and Begg’s tests. After calculation, we found that IL-21 rs6822844 polymorphism could decrease RA risk in overall genetic models (allelic contrast: OR = 0.77, 95% CI = 0.62–0.97, P=0.024; TG versus GG: OR = 0.68, 95% CI = 0.50–0.92, P=0.013, and dominant genetic model: OR = 0.72, 95% CI = 0.55–0.94, P=0.016). Similarly, stratified analysis by race, source of control, significantly decreased association was found in Asians, Caucasians and hospital-based (HB) control source. Finally, in the subgroup analysis of rheumatoid factor (RF) and anti-citrullinated protein antibody (ACPA) status, poorly decreased relationship was detected between IL-21 rs6822844 polymorphism and RF negative and ACPA positive RA risk, respectively. No obvious evidence of publication bias was detected in overall analysis. In summary, our study indicated that IL-21 rs6822844 polymorphism was significantly associated with decreased RA susceptibility.

Polymorphism in Organic Anion-Transporting Polypeptide Gene Related to Methotrexate Response in Rheumatoid Arthritis Treatment

BACKGROUND

Methotrexate (MTX) is still the first-choice drug for the treatment of rheumatoid arthritis (RA). In Japan, MTX doses of up to 16 mg/week were approved in 2011. In this study, we aimed to identify the gene polymorphisms that can predict therapeutic effects of MTX in Japanese patients in current clinical settings.

METHODS

This study involved 171 patients with RA (all Japanese nationals, age 63.5±10.0 years) who had been administered MTX. The analyzed polymorphisms included 82 single nucleotide polymorphisms (SNPs) involved in the MTX pharmacological pathway or in the pathogenesis of RA. Responders were patients who showed high sustained remission or low disease activity with MTX or conventional disease-modifying anti-rheumatic drugs (DMARDs) treatment beyond 6 months. Non-responders were patients who showed moderate or high disease activity, who were prescribed biological DMARDs. A logistic model was constructed with Responder/Non-responder as the target variable, and minor allele frequency was set as an explanatory variable.

RESULTS

None of the 82 SNPs targeted for analysis met the Bonferroni significance threshold of 6.098×10^-4. However, we identified SLCO1B1 rs11045879 as an SNP that might yield significant results if the number of patients were to be increased (P=0.015).

CONCLUSIONS

The rs11045879 minor allele in the SLCO1B1 gene is a potential predictor of non-responders to MTX treatment among Japanese RA patients. In future collaborative research, we will investigate whether the association with SLCO1B1 polymorphism is significant by performing statistical analysis with a larger study population.

Are genetic variations in IL-21-IL-23R-IL-17A cytokine axis involved in a pathogenic pathway of rheumatoid arthritis? Bayesian hierarchical meta-analysis

Inflammatory cytokines have been established to be involved in the pathogenesis of rheumatoid arthritis (RA). The genetic polymorphisms in the interleukin (IL) 23 receptor (IL23R), IL21, and IL17 have been associated with RA risk. However, there is no conclusive understanding of the genes encoding the immunoinflammatory IL-21-IL-23R-IL-17A pathway in RA aetiopathogenesis. This meta-analysis was conducted to attain this goal. A comprehensive literature search was conducted in Scopus and PubMed to look for the relevant case-control studies up until 2018. A Bayesian hierarchical meta-analysis was carried out to assess the association between the polymorphisms and the risk of RA. The association was estimated by calculating the logarithm of odds ratio (Log OR) and 95% credible interval (95% CI). In this meta-analysis, 37 case-control studies comprising 23,506 RA patients and 25,984 healthy individuals were found for analyzing the IL23R, IL21, and IL1A gene polymorphism and risk of RA. In the IL23R gene rs1343151 SNP, the minor A allele significantly increased the risk of RA (Log OR = 0.085, 95% CI = 0.008, 0.156). Moreover, the minor AA genotype was significantly associated with increased RA risk (Log OR = 0.176, 95% CI = 0.028, 0.321). In addition, the C allele of the IL23R gene rs2201841 SNP significantly decreased the disease risk (Log OR = -0.544, 95% CI = -1.0, -0.065). Since Bayesian meta-analysis is a powerful strategy to pool the data, it can be mentioned that genetic polymorphisms of IL23R, but not IL21 and IL17A, are involved in susceptibility to RA.

Genetic implications in the pathogenesis of rheumatoid arthritis; an updated review

Three important factors, including genetics, environment factors and autoimmunity play a role in the pathogenesis of rheumatoid arthritis (RA). The heritability of RA has been accounted to be 50-60%, while the HLA involvement in heritability of the disease has been accounted to be 10-40%. It has been documented that shared epitope (SE) alleles, such as HLA-DRB1*01 and DRB1*04, some HLA alleles like HLA-DRB1*13 and DRB1*15 are connected to RA susceptibility. An advanced classification of SE categorizes SE alleles into four main groups namely, S1, S2, S3D, and S3P. The S2 and S3P groups have been linked to susceptibility of seropositive RA. Various genome-wide association studies (GWAS) have discovered many susceptibility loci implicated in pathogenesis of RA. Some of the important single nucleotide polymorphisms (SNPs) linked to RA are TRAF1, STAT4, CTLA4, IRF5, CCR6, PTPN22, IL23R, and PADI4. HLA and non-HLA genes may discriminate anti-cyclic citrullinated peptide (anti-CCP) antibody-positive and anti-CCP-negative RA groups. Furthermore, risk of the disease has also been linked to environmental agents, mainly cigarette smoking. Pharmacogenomics has also confirmed SNPs or genetic patterns that might be linked to drugs responses. Different aspects of genetic involvement in the pathogenesis, etiology, and RA complications are reviewed in this article.

The genetic pathogenesis, diagnosis and therapeutic insight of rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease that causes chronic inflammation of the joints. RA is a heterogeneous disorder caused by an abnormal autoimmune response triggered by the complex interactions of genetic and environmental factors that contribute to RA etiology. However, its underlying pathogenic mechanisms are yet to be fully understood. In this review, I provide an overview of the pathogenesis, diagnosis and therapeutic insight in the clinical management of RA in light of the recent updates to classification criteria and recent discoveries of genetic loci associated with susceptibility for RA.

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.

Genetic variants within the TNFRSF1B gene and susceptibility to rheumatoid arthritis and response to anti-TNF drugs: a multicenter study

BACKGROUND

Recent research suggests that genetic variants in the tumor necrosis factor receptor 2 (TNFRSF1B) gene may have an impact on susceptibility to rheumatoid arthritis (RA) and drug response. The present population-based case-control study was carried out to evaluate whether 5 tagging single-nucleotide polymorphisms (SNPs) within the TNFRSF1B gene are associated with the risk of RA and response to antitumor necrosis factor (TNF) drugs.

METHODS

The study population included 1412 RA patients and 1225 healthy controls. A subset of 596 anti-TNF-naive RA patients was selected to assess the association of TNFRSF1B SNPs and drug response according to the EULAR response criteria.

RESULTS

We found that carriers of the TNFRSF1Brs3397C allele had a significantly increased risk of developing RA (P=0.0006). Importantly, this association remained significant after correction for multiple testing. We also confirmed the lack of association of the TNFRSF1Brs1061622 SNP with the risk of RA in the single-SNP analysis (P=0.89), but also through well-powered meta-analyses (PDOM=0.67 and PREC=0.37, respectively). In addition, our study showed that carriers of the TNFRSF1Brs3397C/C, TNFRSF1Brs1061622G/G, and TNFRSF1Brs1061631A/A genotypes had an increased risk of having a worse response to anti-TNF drugs at the level of P less than 0.05 (P=0.014, 0.0085 and 0.028, respectively). We also observed that, according to a log-additive model, carriers of the TNFRSF1Brs3397C or TNFRSF1Brs1061622G alleles showed an increased risk of having worse response to anti-TNF medications (P=0.018 and 0.0059). However, the association of the TNFRSF1Brs1061622 SNP only reached marginal significance after correction for multiple testing according to a log-additive model (P=0.0059) and it was not confirmed through a meta-analysis (PDOM=0.12).

CONCLUSION

Our results suggest that the TNFRSF1Brs3397 variant may play a role in modulating the risk of RA, but does not provide strong evidence of an impact of TNFRSF1B variants in determining response to anti-TNF drugs.

Association of STAT4 rs7574865 and PTPN22 rs2476601 polymorphisms with rheumatoid arthritis and non-systemically reacting antibodies in Egyptian patients

The aim of this study was to investigate association of protein tyrosine phosphatase non-receptor type 22 (PTPN22) rs2476601 and signal transducer and activator of transcription 4 (STAT4) rs7574865 polymorphisms with rheumatoid arthritis (RA) susceptibility and to assess potential association with the status of rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) antibodies, serum neopterin, and disease activity. RF, anti-CCP antibodies, and neopterin were assayed in serum of 100 unrelated RA patients and 114 controls. STAT4 rs7574865 G/T and PTPN22 rs2476601 C/T polymorphisms were genotyped by the TaqMan allelic discrimination method. The frequency of STAT4 variant allele was significantly higher in RA patients than in controls (p = 0.01), while the variant allele of PTPN22 was identified in only two RA patients, in a heterozygous form and in none of control subjects. The frequency of STAT4 variant allele carrier genotypes (GT+TT) was significantly higher among RA patients than in controls (43.7 vs. 10.5%, p = 0.02) and associated with RA under additive and dominant models. The frequency of RF and anti-CCP positivity was significantly higher among RA patients carrying T allele genotypes compared to patients carrying wild genotype (P = 0.02 and 0.04, respectively). No significant associations between STAT4 variant and serum neopterin or disease activity parameters were identified. Our study confirmed the association of STAT4 rs7574865 polymorphism with RA and was the first to indicate an association with RF and anti-CCP antibodies positivity. We also found PTPN22 rs2476601 has no role in susceptibility to RA in Egyptian patients.

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.

Association of rs6822844 within the KIAA1109/TENR/IL2/IL21 locus with rheumatoid arthritis in the Algerian population

Increasing evidence suggests that the rs6822844, within KIAA1109/TENR/IL2/IL21 gene cluster on 4q27, is strongly associated with rheumatoid arthritis (RA) in the Caucasian population. The aim of this study is to investigate the possible association between the SNP rs6822844 and susceptibility to RA in the Algerian Maghreb population, and to explore the association with the clinical and immunological features of RA. The polymorphism rs6822844 was genotyped in 323 RA patients and 323 healthy individuals using the TaqMan assay. A strong association of IL2/IL21 with RA susceptibility was detected in the Algerian population [odds ratio (OR) = 2.57 (95% confidence interval (CI) 1.74-3.83), P = 10(-4) ]. Our results revealed that IL2/IL21 predisposed to disease development in both autoantibody positive and negative disease. Meanwhile, the association was stronger in RA patients with anti-cyclic citrullinated peptides (ACPA) positive than those with ACPA negative [OR = 2.30 (95% CI 1.53-3.51), P = 10(-4) and OR = 1.98 (95% CI 1.01-4.22), P = 0.037, respectively]. Moreover, our findings showed a moderate association of the rs6822844 polymorphism with disease activity (P = 0.014). This study indicates for the first time that there is a strong association between IL2/IL21 rs6822844 variant and susceptibility to RA in the Algerian population, and that this association was independent from the autoantibodies status of RA patients.

Understanding the role of cytokines in the pathogenesis of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic, inflammatory autoimmune disease of unknown etiology. It is characterized by the presence of rheumatoid factor and anti-citrullinated peptide antibodies. Initial phase of RA involves the activation of both T and B cells. Cytokines have a crucial role in the pathophysiology of RA as pro-inflammatory cytokines such as TNFα, IL-1, IL-17 stimulates inflammation and degradation of bone and cartilage. There occurs an imbalance between the pro- and anti-inflammatory cytokine activities which leads to multisystem immune complications. There occurs a decline in the number of Treg cells which may also play an important role in pathophysiology of the disease. In RA patients, serum or plasma level of cytokines may indicate the severity of disease. Cytokine gene polymorphism could be used as markers of susceptibility and severity of RA. Anti-cytokine agents seem to emerge as potent drug molecules to treat RA. Many clinical trials are ongoing and several positive results have been obtained. There is a need to develop potential anti-cytokine agents that target numerous pathways involved in the pathogenesis of RA. This review article describes the effector functions of pro- and anti-inflammatory cytokines and the role of cytokine gene polymorphism in the pathogenesis of RA. Anti-cytokine agents that are currently available and those that are still in clinical trials have also been summarized.

Association of CTLA4 exon-1 polymorphism with the tumor necrosis factor-α in the risk of systemic lupus erythematosus among South Indians

Cytotoxic T lymphocyte associated-antigen (CTLA4) is a potential negative regulatory molecule of T-cells and associated with several autoimmune diseases. Several reports from different ethnic groups showed that the polymorphisms of the CTLA4 gene have been associated with autoimmune diseases including SLE. Therefore, we aimed to investigate the +49 A/G polymorphism in South Indian SLE patients and its association with disease aetiology and serological markers. A total of 534 samples were genotyped for the +49 A/G polymorphism in exon 1 of the CTLA-4 gene through PCR-RFLP method. We found significant association of genotype and allele frequencies with +49 A/G polymorphism in SLE patients. The frequency of the +49 A/G polymorphism rs231775 'GG' genotype was significantly higher in patients with SLE (12.32%) than those in healthy control subjects (4.6%) (OR: 1.797; 95% CI 1.264-2.554; p=0.001). The frequency of mutant allele 'G' also found to be significantly higher in cases (36.01%) than controls (24.92%) (OR: 1.695, 95% CI: 1.298-2.214, p<0.001). We observed significant increase in serum TNF-α, interferon-α, IL-10 and IL-12 in SLE cases compared to controls. We also found a significant association of serum TNF-α, interferon-α, IL-10 and IL-12 with SLE phenotypes. In addition there was a significant increase in serum TNF-α level in "GG" genotype SLE subjects suggesting that it might play a major role in the advancement of SLE disease.

Estimating the Ages of Selection Signals from Different Epochs in Human History

Genetic variation harbors signatures of natural selection driven by selective pressures that are often unknown. Estimating the ages of selection signals may allow reconstructing the history of environmental changes that shaped human phenotypes and diseases. We have developed an approximate Bayesian computation (ABC) approach to estimate allele ages under a model of selection on new mutations and under demographic models appropriate for human populations. We have applied it to two resequencing data sets: An ultra-high depth data set from a relatively small sample of unrelated individuals and a lower depth data set in a larger sample with transmission information. In addition to evaluating the accuracy of our method based on simulations, for each SNP, we assessed the consistency between the posterior probabilities estimated by the ABC approach and the ancient DNA record, finding good agreement between the two types of data and methods. Applying this ABC approach to data for eight single nucleotide polymorphisms (SNPs), we were able to rule out an onset of selection prior to the dispersal out-of-Africa for three of them and more recent than the spread of agriculture for an additional three SNPs.

Study of association of CTLA4 gene variants to non-anterior uveitis

This study was undertaken to investigate the possible genetic association of functional CTLA4 polymorphisms with susceptibility to non-anterior uveitis. Four hundred and seventeen patients with endogenous non-anterior uveitis and 1517 healthy controls of Spanish Caucasian origin were genotyped for the CTLA4 polymorphisms rs733618, rs5742909 and rs231775, using predesigned TaqMan(©) allele discrimination assays. PLINK software was used for the statistical analyses. No significant associations between the CTLA4 polymorphisms and susceptibility to global non-anterior uveitis were found. It was also the case when the potential association of these genetic variants with the anatomical localization of the disease, such as intermediate, posterior or panuveitis, was assessed. Our results do not support a relevant role of these CTLA4 polymorphisms in the non-anterior uveitis genetic predisposition.

Association between KIR gene polymorphisms and rheumatoid arthritis susceptibility: A meta-analysis

OBJECTIVES

The results of studies on association between KIR (killer cell immunoglobulin-like receptors) polymorphisms and susceptibility to RA (rheumatoid arthritis) are inconsistent. To comprehensively evaluate the effect of KIR polymorphisms on the risk of RA, a meta-analysis was carried out.

METHODS

The Web of Science, PubMed, the Chinese Biomedical Database (CBM) and Chinese National Knowledge Infrastructure (CNKI) databases were systematically searched to select studies on the association between KIR polymorphisms and RA. The odds ratio (OR) with 95% confidence interval (95%CI) was obtained.

RESULTS

Nine qualified case-control studies were included in this meta-analysis. The results showed there were two positive associations of 2DL1, 2DS1 (OR2DL1=2.20, 95%CI=1.20-4.01, Praw=0.01, PFDR=0.03; OR2DS1=1.84, 95%CI=1.19-2.85, Praw=0.006, PFDR=0.018) and one negative association of 2DL3 (OR2DL3=0.42, 95%CI=0.22-0.79, Praw=0.006, PFDR=0.018) with susceptibility to RA in East Asians, but not in Caucasians.

CONCLUSION

The current meta-analysis provides evidence that 2DL3 might be a potential protective factor and 2DL1, 2DS1 might be risk factors for RA in East Asians but not in Caucasians.

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.

Association of susceptible genetic markers and autoantibodies in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disorder of unknown aetiology resulting in inflammation of the synovium, cartilage and bone. The disease has a heterogeneous character, consisting of clinical subsets of anti-citrullinated protein antibody (ACPA)-positive and APCA-negative disease. Although, the pathogenesis of RA is incompletely understood, genetic factors play a vital role in susceptibility to RA as the heritability of RA is between 50 and 60%, with the human leukocyte antigen (HLA) locus accounting for at least 30% of overall genetic risk. Non-HLA genes, i.e. tumour necrosis factor-α (TNF-α) within the MHC (major histocompatibility complex) have also been investigated for association with RA. Although, some contradictory results have originated from several studies on TNF-α gene, the data published so far indicate the possible existence of TNF-α gene promoter variants that act as markers for disease severity and response to treatment in RA. The correlation of HLA and non-HLA genes within MHC region is apparently interpreted. A considerable number of confirmed associations with RA and other autoimmune disease susceptibility loci including peptidylarginine deiminase type 4 (PADI4), protein tyrosine phosphatase non-receptor type 22 (PTPN22), signal transducer and activator of transcription (STAT4), cluster of differentiation 244 (CD244) and cytotoxic T lymphocyte-associated antigen 4 (CTLA4), located outside the MHC have been reported recently. In this review, we aim to give an update on recent progress in RA genetics, the importance of the combination of HLA-DRB1 alleles, non-HLA gene polymorphism, its detection and autoantibodies as susceptibility markers for early RA disease.

Identification of rheumatoid arthritis biomarkers based on single nucleotide polymorphisms and haplotype blocks: A systematic review and meta-analysis

Genetics of autoimmune diseases represent a growing domain with surpassing biomarker results with rapid progress. The exact cause of Rheumatoid Arthritis (RA) is unknown, but it is thought to have both a genetic and an environmental bases. Genetic biomarkers are capable of changing the supervision of RA by allowing not only the detection of susceptible individuals, but also early diagnosis, evaluation of disease severity, selection of therapy, and monitoring of response to therapy. This review is concerned with not only the genetic biomarkers of RA but also the methods of identifying them. Many of the identified genetic biomarkers of RA were identified in populations of European and Asian ancestries. The study of additional human populations may yield novel results. Most of the researchers in the field of identifying RA biomarkers use single nucleotide polymorphism (SNP) approaches to express the significance of their results. Although, haplotype block methods are expected to play a complementary role in the future of that field.

Cytotoxic T lymphocyte associated antigen-4 (CTLA-4) +49 A>G gene polymorphism in Egyptian cases with rheumatoid arthritis

BACKGROUND

The gene encoding cytotoxic T lymphocyte associated antigen-4 (CTLA-4) has been reported to be associated with rheumatoid arthritis (RA) in several ethnic populations. The aim of this work is to assess the association of this polymorphism with the susceptibility, activity and functional disability of RA in Egyptian subjects.

SUBJECTS AND METHODS

This study included 112 unrelated RA Egyptian patients who were compared to 122 healthy controls from the same locality. For all subjects, DNA was genotyped for CTLA-4 +49 A>G (rs231775) polymorphism using the PCR-RFLP technique. Antibodies to cyclic citrullinated peptides (anti-CCP) were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The frequency of the CTLA-4 G allele was significantly higher among cases compared to controls (37.1% vs. 23.4%, OR=1.93; 95% CI=1.29-2.89, p=0.002). Also, the frequency of CTLA-4 +49 G allele carriage (AG+GG genotypes) was significantly higher among cases with RA compared to controls (61.6% vs. 41.8%, OR=2.23, 95% CI=1.32-3.77, p=0.003). Logistic regression analysis showed that cases positive to the G allele (GA+GG genotypes) had less frequency of rheumatoid deformities and also a lower DAS28-CRP score, yet with a higher visual analogue scale (VAS) i.e. more functional disability than other cases.

CONCLUSIONS

CTLA-4 +49 G allele carriage was associated with increased susceptibility and functional disability of RA in Egyptian patients.

Interleukins and interleukin receptors in rheumatoid arthritis: Research, diagnostics and clinical implications

Rheumatoid arthritis (RA) is an autoimmune disease, resulting in a chronic, systemic inflammatory disorder. It may affect many tissues and organs, but it primarily affects the flexible joints. In clinical practice patient care generates many questions about diagnosis, prognosis, and treatment. It is challenging for health care specialists to keep up to date with the medical literature. This review summarizes the pathogenesis, the polymorphisms of interleukin and interleukin genes and the standard available and possible future immunologic targets for RA treatment. The identification of disease-associated interleukin and interleukin receptor genes can provide precious insight into the genetic variations prior to disease onset in order to identify the pathways important for RA pathogenesis. The knowledge of the complex genetic background may prove useful for developing novel therapies and making personalized medicine based on the individual’s genetics.

Signal transducer and activator of transcription 4 (STAT4) G>T gene polymorphism in Egyptian cases with rheumatoid arthritis

BACKGROUND

The gene encoding signal transducer and activator of transcription 4 (STAT4) has been reported to be associated with rheumatoid arthritis (RA) in several populations. This work aimed at assessing the association of STAT4 G>T gene polymorphism with the susceptibility, activity and functional disability of RA in Egyptian subjects.

SUBJECTS AND METHODS

This study included 112 unrelated RA Egyptian patients who were compared to 122 healthy unrelated individuals taken from the same locality. For all subjects, DNA was genotyped for STAT4 G>T (rs7574865) polymorphism using the PCR-RFLP technique. Antibodies to cyclic citrullinated peptides (anti-CCP) were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Cases showed a significantly higher frequency of the STAT4 T allele carriage (GT+TT genotypes) compared to controls (51.8% vs. 31.1%, OR = 2.37, 95% CI = 1.39-4.05, p = 0.001). Also the frequency of the STAT4 T allele was significantly higher among cases compared to controls (30.4% vs. 16.8%, OR = 2.16, 95% CI = 1.39-3.35, p = 0.001). Cases positive to the STAT4 T allele (GT+TT genotypes) showed no significant difference compared to those with the GG genotype regarding their clinical and immune parameters. Nonetheless, they showed a more functional disability presented in their significantly higher health assessment questionnaire (HAQ) score (p = 0.02).

CONCLUSIONS

This study gives an extra evidence to the association of the STAT4 T allele with the susceptibility and functional disability of RA.

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.

Cytokine-Mediated Regulation of Plasma Cell Generation: IL-21 Takes Center Stage

During our life, we are surrounded by continuous threats from a diverse range of invading pathogens. Our immune system has evolved multiple mechanisms to efficiently deal with these threats so as to prevent them from causing disease. Terminal differentiation of mature B cells into plasma cells (PC) – the antibody (Ab) secreting cells of the immune system – is critical for the generation of protective and long-lived humoral immune responses. Indeed, efficient production of antigen (Ag)-specific Ab by activated B cells underlies the success of most currently available vaccines. The mature B-cell pool is composed of several subsets, distinguished from one according to size, surface marker expression, location, and Ag exposure, and they all have the capacity to differentiate into PCs. For a B-cell to acquire the capacity to produce Abs, it must undergo an extensive differentiation process driven by changes in gene expression. Two broad categories of Ags exist that cause B-cell activation and differentiation: T cell dependent (TD) or T cell independent (TI). In addition to the B-cell subset and nature of the Ag, it is important to consider the cytokine environment that can also influence how B-cell differentiation is achieved. Thus, while many cytokines can induce Ab-secretion by B cells after activation with mimics of TD and TI stimuli in vitro, they can have different efficacies and specificities, and can often preferentially induce production of one particular Ig isotype over another. Here, we will provide an overview of in vitro studies (mouse and human origin) that evaluated the role of different cytokines in inducing the differentiation of distinct B-cell subsets to the PC lineage. We will place particular emphasis on IL-21, which has emerged as the most potent inducer of terminal B-cell differentiation in humans. We will also focus on the role of IL-21 and defects in B-cell function and how these contribute to human immunopathologies such as primary immunodeficiencies and B-cell mediated autoimmune conditions.

Measles contributes to rheumatoid arthritis: evidence from pathway and network analyses of genome-wide association studies

Growing evidence from epidemiological studies indicates the association between rheumatoid arthritis (RA) and measles. However, the exact mechanism for this association is still unclear now. We consider that the strong association between both diseases may be caused by shared genetic pathways. We performed a pathway analysis of large-scale RA genome-wide association studies (GWAS) dataset with 5,539 cases and 20,169 controls of European descent. Meanwhile, we evaluated our findings using previously identified RA loci, protein-protein interaction network and previous results from pathway analysis of RA and other autoimmune diseases GWAS. We confirmed four pathways including Cytokine-cytokine receptor interaction, Jak-STAT signaling, T cell receptor signaling and Cell adhesion molecules. Meanwhile, we highlighted for the first time the involvement of Measles and Intestinal immune network for IgA production pathways in RA. Our results may explain the strong association between RA and measles, which may be caused by the shared genetic pathway. We believe that our results will be helpful for future genetic studies in RA pathogenesis and may significantly assist in the development of therapeutic strategies.

Genetics in rheumatoid arthritis beyond HLA genes: what meta-analyses have shown?

OBJECTIVE

Rheumatoid arthritis (RA) is a complex disorder with many genetic and environmental factors to account for disease susceptibility. Individual genetic association studies usually suffer from small sample size leading to biased results of polymorphisms association with RA liability. Therefore, meta-analyses seem to resolve this limitation, up to a point, increasing the power of statistical analyses. In this review, we summarize the current knowledge of non-HLA genetic factors contributing to RA predisposition based on meta-analyses.

METHODS

Using the key words: rheumatoid arthritis, meta-analysis, and polymorphism, we searched the PubMed database for the associated articles. Up to the middle of November 2012, seventy-nine articles fulfilled the criteria and highlighted the current findings on the genetic factors contributing to RA susceptibility.

RESULTS

The association with RA was confirmed for 32 gene polymorphisms, being population specific in some cases. However, meta-analyses did not confirm an association in case of 16 gene variants, previously studied in individual studies for their association with RA.

CONCLUSIONS

The use of bioinformatics tools and functional studies of the summarized implicated genes in RA pathogenesis could shed light on the molecular pathways related to the disorder, helping to the development of new drug targets for a better treatment of RA.

Diagnostic value of interleukin 21 and carcinoembryonic antigen levels in malignant pleural effusions

The aim of this study was to evaluate the diagnostic value of interleukin 21 (IL-21) and carcinoembryonic antigen (CEA) in tuberculous pleural effusions (TPEs) and malignant pleural effusions (MPEs). Pleural effusion samples from 103 patients were classified on the basis of diagnosis as TPE (n=51) and MPE (n=52). The concentration of IL-21 was determined by ELISA. Lactate dehydrogenase (LDH), adenosine dehydrogenase (ADA) and CEA levels were also determined in all patients. A significant difference was observed in the levels of ADA and CEA (P<0.01), but not in the levels of LDH (P>0.05) between TPE and MPE. The concentration of IL-21 in MPE was significantly higher compared to TPE (P<0.01). With a threshold value of 4.32 pg/ml, IL-21 had a sensitivity of 76.9% (40/52) and a specificity of 80.4% (41/51). Combined detection of IL-21 and CEA had a sensitivity of 69.2% (36/52) and a specificity of 92.2% (47/51). These two markers can contribute to the differential diagnosis of MPEs.

New insights into the genetics of immune responses in rheumatoid arthritis

Rheumatoid arthritis (RA) is a common autoimmune disease with a strong genetic component. Numerous aberrant immune responses have been described during the evolution of the disease. In later years, the appearance of anti-citrullinated protein antibodies (ACPAs) has become a hallmark for the diagnosis and prognosis of RA. The post-translational transformation of arginine residues of proteins and peptides into citrulline (citrullination) is a natural process in the body, but for unknown reasons autoreactivity towards citrullinated residues may develop in disposed individuals. ACPAs are often found years before clinical manifestations. ACPAs are present in about 70% of RA patients and constitute an important disease marker, distinguishing patient groups with different prognoses and different responses to various treatments. Inside the human leukocyte antigen (HLA) region, some HLA-DRB1 alleles are strongly associated with their production. Genome-wide association studies in large patient cohorts have defined a great number of single nucleotide polymorphisms (SNPs) outside of the HLA region that are associated with ACPA positive (ACPA+) RA. The SNPs are generally located close to or within genes involved in the immune response or signal transduction in immune cells. Some environmental factors such as tobacco smoking are also positively correlated with ACPA production. In this review, we will describe the genes and loci associated with ACPA+ RA or ACPA- RA and attempt to clarify their potential role in the development of the disease.

Meta-analysis reveals an association of STAT4 polymorphisms with systemic autoimmune disorders and anti-dsDNA antibody

Signal transducer and activator of transcription 4 (STAT4) has been recently identified as a susceptibility gene for multiple autoimmune diseases. Here we performed a comprehensive analysis of the association between STAT4 and several different autoimmune disorders to identify potential common inflammatory principles behind this association. Our meta-analysis revealed that the STAT4 rs7574865 polymorphism is associated with four autoimmune diseases with systemic pathology, including systemic lupus erythematosus (OR = 1.52; 95% CI = 1.48 - 1.56, P<1.0 × 10(-16)), rheumatoid arthritis (OR = 1.27; 95% CI = 1.21 - 1.33, P < 1.00 × 10(-16)), systemic sclerosis (OR = 1.38; 95% CI = 1.27 - 1.50, P < 1.44 × 10(-14)), and primary Sjogren's syndrome (OR = 1.32; 95% CI = 1.01 - 1.73, P = 4.40 × 10(-2)), while no association was found with type I diabetes, juvenile idiopathic arthritis, ulcerative colitis and Crohn's disease. Furthermore, the stratified meta-analysis also demonstrate that the STAT4 rs7574865 polymorphism is associated with the presence of autoantibodies with systemic reactivity (anti-ds-DNA antibodies) in SLE patients (OR = 1.37; 95% CI = 1.21 - 1.56, P = 1.12 × 10(-6)). However, no such specific association was seen in RA with regard to the presence of non-systemically reacting antibodies, including rheumatoid factor and anti-cyclic citrullinated peptide antibodies. Taken together, these results suggest that STAT4 polymorphisms are associated with autoimmune diseases which are characterized by a systemic pathology and anti-dsDNA antibody.

The role of miR-155 in regulatory T cells and rheumatoid arthritis

Recently, various micro(mi)RNAs have been found deregulated in the setting of rheumatoid arthritis (RA), but their role in the pathogenesis of this disease remains a matter of debate. In the meanwhile, increasing evidence indicates a defective function of regulatory T cells (Tregs) in RA. This review discusses relevant studies addressing the function of Tregs and Cytotoxic T-Lymphocyte Antigen 4 in RA, provides recent data on the role of miRNAs for Tregs homeostasis, and focuses on the role of miR-155 in Tregs. In a final perspective section we discuss the potential impact of therapeutic miR-155 modulation in RA.

Association between polymorphism in STAT4 gene and risk of rheumatoid arthritis: a meta-analysis

BACKGROUND

Rheumatoid arthritis (RA) is a common chronic inflammatory autoimmune disease, affecting 1% of the population worldwide. Single nucleotide polymorphisms (SNPs) of signal transducer and activator of transcription 4 (STAT4) gene are suspected to have some relationship with the risk of RA. This meta-analysis aimed to evaluate the relationship between the polymorphism rs7574865 in STAT4 gene with RA and also examine whether the associations that have been reported in these studies differ between ethnic groups.

METHODS

We retrieved the relevant articles from PubMed, EMBASE and the China National Knowledge Infrastructure (CNKI) databases. The odds ratios (ORs) and their 95% confidence intervals (95% CIs) associated with the minor T allele of STAT4 rs7574865 SNP were extracted from the published studies and included in the analysis. Meta-analyses were performed on the total data set and separately for the major ethnic groups and RF and anti-CCP status. All analyses were performed using the Stata software.

RESULTS

Twenty-three articles were included in the present analysis. Meta-analysis showed an association between the STAT4 polymorphism and RA in all subjects (OR=1.299, 95%CI=1.230-1.371, P<0.001). Stratified analyses indicated that the STAT4 rs7574865 T allele was significantly associated with RA in both Caucasians and Asians, in both positive and negative RF patients versus controls, also significantly in the presence of anti-CCP, both positive and negative. As for genotypes of rs7574865 polymorphism, all the results were significant, no matter in total subjects or stratified analyses by ethnic groups or by RF and anti-CCP status.

CONCLUSION

Genetic polymorphism rs7574865 in STAT4 gene might be associated with RA susceptibility in total subjects, major ethnic groups and different status of anti-CCP or RF.

Anti-neutrophil cytoplasmic antibodies in rheumatoid arthritis: two case reports and review of literature

Background

Anti-neutrophil cytoplasmic antibodies are typically detected in anti-neutrophil cytoplasmic antibody associated vasculitis, but are also present in a number of chronic inflammatory non-vasculitic conditions like rheumatoid arthritis. Rare cases of granulomatosis with polyangiitis (formerly known as Wegener’s granulomatosis, a vasculitic disorder frequently associated with the presence of anti-neutrophil cytoplasmic antibodies) in patients with rheumatoid arthritis have been described in literature.

Case presentation

We report two middle-aged female patients with rheumatoid arthritis who developed anti-neutrophil cytoplasmic antibodies and symptoms reminiscent of granulomatosis with polyangiitis. Despite the lack of antibodies specific for proteinase 3 and the absence of a classical histology, we report a probable case of granulomatosis with polyangiitis in the first patient, and consider rheumatoid vasculitis in the second patient.

Conclusion

Taken together with previous reports, these cases highlight that anti-neutrophil cytoplasmic antibodies have to be evaluated very carefully in patients with rheumatoid arthritis. In this context, anti-neutrophil cytoplasmic antibodies detected by indirect immunofluorescence appear to have a low diagnostic value for granulomatosis with polyangiitis. Instead they may have prognostic value for assessing the course of rheumatoid arthritis.

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

OBJECTIVE

STAT3 and 4 are, among other factors, critical for the interleukin 12 (IL-12)-mediated Th1 response, for transfer of IL-23 signals, and for survival and expansion of Th17 cells. We investigated the association of STAT3 and STAT4 polymorphisms with serologically distinct subgroups of rheumatoid arthritis (RA).

METHODS

A total of 41 single-nucleotide polymorphisms (SNP) within STAT3 and STAT1-STAT4 loci were investigated in a Swedish cohort of 2043 RA cases and 1115 controls. Nine of the associated SNP were tested in a Spanish cohort of 1223 RA cases and 1090 controls.

RESULTS

Fourteen SNP in the STAT3 and STAT1-STAT4 loci were associated with anticitrullinated protein antibody (ACPA)-negative RA in the Swedish cohort. Three of the SNP in STAT4 and 2 SNP in STAT3 remained associated with ACPA-negative RA after considering the Spanish results. In addition, rs7574865 and rs10181656, in STAT4, were associated with ACPA-positive RA in the Swedish study. One of these SNP, rs7574865, showed a similar pattern of the association in serologically distinct subgroups of RA in a metaanalysis of all 7 published studies.

CONCLUSION

Our findings suggest that variants in STAT genes may contribute differentially to susceptibility to RA in seropositive and in seronegative patients.

Association of STAT4 rs7574865 polymorphism with autoimmune diseases: a meta-analysis

The association between the signal transducer and activator of transcription 4 (STAT4) gene rs7574865 single nucleotide polymorphism and different autoimmune diseases remains controversial and ambiguous. We conducted this study to investigate whether combined evidence shows the association between STAT4 rs7574865 polymorphism and autoimmune diseases. Comprehensive Medline search and review of the references were used to get the relevant reports published before September 2011. Meta-analysis was conducted for genotype T/T (recessive effect), T/T + G/T (dominant effect) and T allele in random effects models. 40 studies with 90 comparisons including 32 systemic lupus erythematosus (SLE), 19 rheumatoid arthritis (RA), 3 type 1 diabetes (T1D), 11 Systemeric Sclerosis (SSc), 4 inflammatory bowed diseases (IBD), 3 Primary Sjogren's syndrome (pSS), 4 juvenile idiopathic arthritis (JIA), 2 Primary antiphospholipid syndrome (APS), 1 Autoimmune thyroid diseases, 1 multiple sclerosis, 1 Psoriasis, 1 Wegener's granulomatosis, 1 Type 2 diabetes, and 1 giant cell arteritis disease were available for this meta-analysis. The overall odds ratios for rs7574865 T-allele significantly increased in SLE, RA, T1D, SSc, JIA, and APS (OR = 1.56, 1.25, 1.13, 1.34, 1.25, and 2.15, respectively, P < 0.00001) and in IBD-UC and pSS (OR = 1.11 and 1.33, respectively, P < 0.05). This meta-analysis demonstrates that the STAT4 rs7574865 T allele confers susceptibility to SLE, RA, T1D, SSc, JIA, APS, IBD-UC, and pSS patients, supporting the hypothesis of association between STAT4 gene polymorphism and subgroup of autoimmune diseases.

Generation and characterization of human anti-human IL-21 neutralizing monoclonal antibodies

Interleukin-21 (IL-21) is a type I four-helical bundle cytokine that exerts a variety of significant effects on many hematopoietic cells, including T and B lymphocytes and natural killer cells. IL-21 is produced predominantly by CD4+ T cells and natural killer T cells and, when aberrantly overexpressed, appears to play important roles in a wide variety of autoimmune disorders. To generate potential therapeutic reagents capable of inhibiting IL-21 for clinical use, we immunized human immunoglobulin transgenic mice with IL-21 and then identified and cloned a panel of human anti-human IL-21 binding monoclonal antibodies. IL-21 neutralizing and IL-21-binding, non-neutralizing antibodies were assigned to distinct epitope "bins" based on surface plasmon resonance competition studies. The most potent neutralizing antibodies had extremely high (sub pM) affinity for IL-21 and were able to block IL-21 activity in various biological assays using either an IL-21R-transfected pre-B-cell line or primary human B cells, and their neutralizing activity was, in some cases, superior to that of a soluble form of the high affinity heterodimeric IL-21 receptor. Characterization of this panel of IL-21 antibodies provided the basis for the selection of a therapeutic candidate antibody capable of inhibiting IL-21 activity for the treatment of autoimmune and inflammatory diseases.

Production of autoantibodies against citrullinated antigens/peptides by human B cells

Autoantibodies against citrullinated protein Ags (ACPA) are associated with the development of rheumatoid arthritis (RA). This immune response against citrullinated protein Ags, which is thought to be facilitated by certain MHC HLA-DR alleles, is highly specific for this disease and has been speculated to be involved in the pathogenesis. We have previously studied cultures of B cells for the production of Abs against HLA Ags. The aim of the current study was to examine the role of B cells in the production of ACPA in patients with RA. Peripheral blood B cells from RA patients and healthy people were cultured with EL4-B5, a murine cell line expressing human CD40L, and with T cell factors to stimulate the in vitro production of Abs by B cells isolated from peripheral blood. ACPA were produced by cultured B cells from RA patients, as determined by reactivity to cyclic citrullinated peptide (CCP). The results showed that 22% of the healthy persons tested also had B cells that could produce ACPA. Patients with HLA-DR alleles carrying the RA-associated shared epitope appeared to have more B cells with autoimmune potential for CCP than those without such HLA alleles (odds ratio 8.1, p = 0.001). In healthy individuals, anti-CCP-producing B cells were also observed more frequently if the RA-associated MHC genes were present (odds ratio 8.0, p = 0.01). Analysis of B cells in cultures may shed light on the interaction of genetic and environmental factors in the development of RA.