Do Genetic Susceptibility Variants Associate with Disease Severity in Early Active Rheumatoid Arthritis?

Association between PYTPN22 rs2476601, VEGF rs833070, TNFAIP3 rs6920220 Polymorphisms and Risk for Rheumatoid Arthritis in Early Undifferentiated Arthritis Patients: A Pilot Study

Background and Objectives: About 40% of early undifferentiated arthritis (UA) progresses to rheumatoid (RA) or other chronic arthritis. Novel diagnostic tools predicting the risk for this progression are needed to identify the patients who would benefit from early aggressive treatment. Evidence on the role of single-nucleotide polymorphisms (SNPs) in the development of RA has emerged. The aim of our study was to investigate the association between rs2476601, rs833070, and rs6920220 SNPs and UA progression to RA. Materials and Methods: Ninety-two UA patients were observed for 12 months. At study entry, demographic and clinical characteristics were recorded, musculoskeletal ultrasonography was performed, and blood samples were drawn to investigate levels of inflammatory markers, rheumatoid factor (RF), anti-citrullinated protein antibodies (anti-CCP)detect SNPs. After 12 months, UA outcomes were assessed, and patients were divided into two (RA and non-RA) groups. The association between the risk of progression to chronic inflammatory arthritis and analyzed SNPs was measured by computing odds ratios (OR). Results: After a 12-month follow-up, 27 (29.3%) patients developed RA, and 65 (70.7%) patients were assigned to the non-RA group. The arthritis of 21 patients (22.8%) from the non-RA group resolved completely, while the other 44 (47.2%) patients were diagnosed with another rheumatic inflammatory disease. The patients who developed RA had a significantly greater number of tender and swollen joints (p = 0.010 and p = 0.021 respectively) and were more frequently RF or anti-CCP (p < 0.001), and both RF and anti-CCP positive (p < 0.001) at the baseline as compared with the patients in the non-RA group. No significant association between rs2476601 (OR = 0.99, p = 0.98), rs833070 (OR = 1.0, p = 0.97), and rs6920220 (OR = 0.48, p = 0.13) polymorphisms and the risk of developing RA were found. Conclusions: No association between analyzed SNPs and a greater risk to progress from UA to RA was confirmed, although patients with rs6920220 AA + AG genotypes had fewer tender joints at the disease onset.

Relationship between SHP2 gene polymorphisms and systemic lupus erythematosus risk

OBJECTIVE

Systemic lupus erythematosus (SLE) is a complex autoimmune disorder. SHP2, a non-transmembrane member of the protein tyrosine phosphatase (PTP) family, can be involved in multiple signaling pathways in inflammatory response. To date, it remains to be investigated whether polymorphisms in the SHP2 gene are correlated with SLE in the Chinese Han population.

METHOD

A study comprising 320 SLE patients and 400 healthy individuals was performed. Three single nucleotide polymorphisms (rs4767860, rs7132778, rs7953150) of the SHP2 gene were genotyped using the Kompetitive Allele-Specific Polymerase Chain Reaction method.

RESULTS

Genotypes of rs4767860 (AA, AG + AA) and rs7132778 (AA, AC + AA), and alleles of rs4767860 (A) and rs7132778 (A) were associated with SLE risk. Genotype AA of rs7132778 and allele A of rs7132778 and rs7953150 were associated with oral ulcers in SLE patients. Allele C of rs7132778 and genotype AA and allele A of rs7953150 were associated with pyuria. Patients who carried AA genotype and allele A of rs7953150 are more likely to develop hypocomplementemia. AA and AG genotype frequencies are more raised in patients with SLE with alopecia than in those without alopecia. Patients who carried AA and AG genotypes of rs4767860 had elevated C-reactive protein levels.

CONCLUSION

Gene polymorphisms of SHP2 (rs4767860, rs7132778) are relevant to SLE susceptibility.

Polygenic risk scores are associated with radiographic progression in patients with rheumatoid arthritis

OBJECTIVE

To investigate whether polygenic risk score (PRS) using data from a genome-wide association study (GWAS) for rheumatoid arthritis (RA) susceptibility can be a predictor for radiographic progression.

METHODS

We constructed the PRS using GWAS summary data for disease susceptibility to predict Sharp/van der Heijde score (SHS) changes in first five years from the onset (the top quartile of SHS changes was defined as severe progression and the remaining as non-severe progression). We selected the best model in a training set (n = 500) and validated it in a testing set (n = 740). We evaluated the performance of PRS in univariable and multivariable analyses with other factors to predict severe progression.

RESULTS

PRS constructed of 43,784 SNPs significantly differed between severe and non-severe progression in both training (P = 0.0064) and testing sets (P = 0.017). The patients with the top quintile PRS had a higher risk for severe progression compared to those with the bottom quintile (odds ratio (OR) 1.90, P = 0.0022), which was higher when restricted to younger-onset patients (OR 5.06, P = 0.00038). The top quintile PRS and ACPAs positive groups had significantly higher proportion of patients with severe progression compared to the remaining groups (P = 0.00052, and 0.0022, respectively). Multivariable analysis showed that PRS (P = 0.00019) as well as sex (female) (P = 0.0033), ACPAs (P = 0.0023), and BMI (P = 0.031) were independent risk factors.

CONCLUSION

PRS using GWAS data for RA susceptibility is associated with radiographic progression.

Systematic Review with Meta-analysis: The Impact of Co-occurring Immune-mediated Inflammatory Diseases on the Disease Course of Inflammatory Bowel Diseases

BACKGROUND AND AIMS

Patients with inflammatory bowel diseases (IBDs) are at risk of developing a variety of other immune-mediated inflammatory diseases (IMIDs). The influence of co-occurring IMIDs on the disease course of IBD remains unknown. The aim of this study was therefore to conduct a systematic review and meta-analysis of the impact of IMIDs on phenotypic presentation and outcome in patients with IBD.

METHODS

PubMed and Embase were searched from their earliest records through December 2018 and updated in October 2019 for studies reporting proportions or ratios of IBD-related disease outcomes in patients with and without co-occurring IMIDs. Meta-analyses were performed to estimate summary proportions and risks of the main outcomes. PRISMA guidelines were used, and study quality was assessed according to the Newcastle-Ottawa Scale.

RESULTS

A total of 93 studies were identified, comprising 16,064 IBD patients with co-occurring IMIDs and 3,451,414 IBD patients without IMIDs. Patients with IBD and co-occurring IMIDs were at increased risk of having extensive colitis or pancolitis (risk ratio, 1.38; 95% Cl, 1.25-1.52; P < 0.01, I2 = 86%) and receiving IBD-related surgeries (risk ratio, 1.17; 95% Cl, 1.01-1.36; P = 0.03; I2 = 85%) compared with patients without IMIDs. Co-occurrence of IMIDs other than primary sclerosing cholangitis in patients with IBD was associated with an increased risk of receiving immunomodulators (risk ratio, 1.15; 95% Cl, 1.06-1.24; P < 0.01; I2 = 60%) and biologic therapies (risk ratio, 1.19; 95% Cl, 1.08-1.32; P < 0.01; I2 = 53%).

CONCLUSION

This meta-analysis found that the presence of co-occurring IMIDs influences the disease course of IBD, including an increased risk of surgery and its phenotypical expression.

Development and application of a PCR-HRM molecular diagnostic method of SNPs linked with TNF inhibitor efficacy

Background Clinical evidence indicates that genetic variations may interfere with the mechanism of drug action. Recently, it has been reported that the single nucleotide polymorphisms (SNPs) of STAT4, PTPN2, PSORS1C1 and TRAF3IP2RA genes are associated with the clinical efficacy of tumor necrosis factor (TNF) inhibitors in the treatment of rheumatoid arthritis (RA) patients. Therefore, the detection of the SNPs linked with TNF inhibitor efficacy may provide an important basis for the treatment of RA. This study intended to establish molecular diagnostic methods for genotyping the linked SNPs based on high resolution melting (HRM) curve analysis. Methods The polymerase chain reaction-HRM (PCR-HRM) curve analysis detecting systems were established by designing the primers of the four SNPs, rs7574865G>T, rs7234029A>G, rs2233945C>A and rs33980500C>T, and the performance and clinical applicability of which were evaluated by using the Sanger sequencing method and genotyping test for 208 clinical samples. Results The self-developed molecular diagnostic methods of PCR-HRM were confirmed to be able to correctly genotype the four SNPs, the sensitivity and specificity of which were 100% in this study. The repeatability and reproducibility tests showed that there is little variable in intra-assay and inter-assay (the coefficient of variation ranged from 0.01% to 0.07%). The slight changes of DNA template and primer concentrations, PCR cycle number and reaction system volume had no significant effect on the genotyping performance of the method. The PCR-HRM assays were also applied to other PCR thermocyclers with HRM function and use different saturation fluorescent dyes. Conclusions The PCR-HRM genotyping method established in this study can be applied to the routine molecular diagnosis of rs7574865, rs7234029, rs2233945 and rs33980500.

Steroid hormone-related polymorphisms associate with the development of bone erosions in rheumatoid arthritis and help to predict disease progression: Results from the REPAIR consortium

Here, we assessed whether 41 SNPs within steroid hormone genes associated with erosive disease. The most relevant finding was the rheumatoid factor (RF)-specific effect of the CYP1B1, CYP2C9, ESR2, FcγR3A, and SHBG SNPs to modulate the risk of bone erosions (P = 0.004, 0.0007, 0.0002, 0.013 and 0.015) that was confirmed through meta-analysis of our data with those from the DREAM registry (P = 0.000081, 0.0022, 0.00074, 0.0067 and 0.0087, respectively). Mechanistically, we also found a gender-specific correlation of the CYP2C9_rs1799853T/T genotype with serum vitamin D3 levels (P = 0.00085) and a modest effect on IL1β levels after stimulation of PBMCs or blood with LPS and PHA (P = 0.0057 and P = 0.0058). An overall haplotype analysis also showed an association of 3 ESR1 haplotypes with a reduced risk of erosive arthritis (P = 0.009, P = 0.002, and P = 0.002). Furthermore, we observed that the ESR2, ESR1 and FcγR3A SNPs influenced the immune response after stimulation of PBMCs or macrophages with LPS or Pam3Cys (P = 0.002, 0.0008, 0.0011 and 1.97•10⁻⁷). Finally, we found that a model built with steroid hormone-related SNPs significantly improved the prediction of erosive disease in seropositive patients (P_RF+ = 2.46•10⁻⁸) whereas no prediction was detected in seronegative patients (P_RF− = 0.36). Although the predictive ability of the model was substantially lower in the replication population (P_RF+ = 0.014), we could confirm that CYP1B1 and CYP2C9 SNPs help to predict erosive disease in seropositive patients. These results are the first to suggest a RF-specific association of steroid hormone-related polymorphisms with erosive disease.

Genetic associations with radiological damage in rheumatoid arthritis: Meta-analysis of seven genome-wide association studies of 2,775 cases

BACKGROUND

Previous studies of radiological damage in rheumatoid arthritis (RA) have used candidate-gene approaches, or evaluated single genome-wide association studies (GWAS). We undertook the first meta-analysis of GWAS of RA radiological damage to: (1) identify novel genetic loci for this trait; and (2) test previously validated variants.

METHODS

Seven GWAS (2,775 RA cases, of a range of ancestries) were combined in a meta-analysis. Radiological damage was assessed using modified Larsen scores, Sharp van Der Heijde scores, and erosive status. Single nucleotide polymophsim (SNP) associations with radiological damage were tested at a single time-point using regression models. Primary analyses included age and disease duration as covariates. Secondary analyses also included rheumatoid factor (RF). Meta-analyses were undertaken in trans-ethnic and European-only cases.

RESULTS

In the trans-ethnic primary meta-analysis, one SNP (rs112112734) in close proximity to HLA-DRB1, and strong linkage disequilibrium with the shared-epitope, attained genome-wide significance (P = 4.2x10-8). In the secondary analysis (adjusting for RF) the association was less significant (P = 1.7x10-6). In both trans-ethnic primary and secondary meta-analyses 14 regions contained SNPs with associations reaching P<5x10-6; in the European primary and secondary analyses 13 and 10 regions contained SNPs reaching P<5x10-6, respectively. Of the previously validated SNPs for radiological progression, only rs660895 (tagging HLA-DRB1*04:01) attained significance (P = 1.6x10-5) and had a consistent direction of effect across GWAS.

CONCLUSIONS

Our meta-analysis confirms the known association between the HLA-DRB1 shared epitope and RA radiological damage. The lack of replication of previously validated non-HLA markers highlights a requirement for further research to deliver clinically-useful prognostic genetic markers.

Comparative study for haplotype block partitioning methods - Evidence from chromosome 6 of the North American Rheumatoid Arthritis Consortium (NARAC) dataset

Haplotype-based methods compete with “one-SNP-at-a-time” approaches on being preferred for association studies. Chromosome 6 contains most of the known genetic biomarkers for rheumatoid arthritis (RA) disease. Therefore, chromosome 6 serves as a benchmark for the haplotype methods testing. The aim of this study is to test the North American Rheumatoid Arthritis Consortium (NARAC) dataset to find out if haplotype block methods or single-locus approaches alone can sufficiently provide the significant single nucleotide polymorphisms (SNPs) associated with RA. In addition, could we be satisfied with only one method of the haplotype block methods for partitioning chromosome 6 of the NARAC dataset? In the NARAC dataset, chromosome 6 comprises 35,574 SNPs for 2,062 individuals (868 cases, 1,194 controls). Individual SNP approach and three haplotype block methods were applied to the NARAC dataset to identify the RA biomarkers. We employed three haplotype partitioning methods which are confidence interval test (CIT), four gamete test (FGT), and solid spine of linkage disequilibrium (SSLD). P-values after stringent Bonferroni correction for multiple testing were measured to assess the strength of association between the genetic variants and RA susceptibility. Moreover, the block size (in base pairs (bp) and number of SNPs included), number of blocks, percentage of uncovered SNPs by the block method, percentage of significant blocks from the total number of blocks, number of significant haplotypes and SNPs were used to compare among the three haplotype block methods. Individual SNP, CIT, FGT, and SSLD methods detected 432, 1,086, 1,099, and 1,322 associated SNPs, respectively. Each method identified significant SNPs that were not detected by any other method (Individual SNP: 12, FGT: 37, CIT: 55, and SSLD: 189 SNPs). 916 SNPs were discovered by all the three haplotype block methods. 367 SNPs were discovered by the haplotype block methods and the individual SNP approach. The P-values of these 367 SNPs were lower than those of the SNPs uniquely detected by only one method. The 367 SNPs detected by all the methods represent promising candidates for RA susceptibility. They should be further investigated for the European population. A hybrid technique including the four methods should be applied to detect the significant SNPs associated with RA for chromosome 6 of the NARAC dataset. Moreover, SSLD method may be preferred for its favored benefits in case of selecting only one method.

Future Directions of Genomics Research in Rheumatic Diseases

Recent developments in human genome genotyping and sequencing technologies, such as genome-wide association studies and whole-genome sequencing analyses, have successfully identified several risk genes of rheumatic diseases. Fine-mapping studies using the HLA imputation method revealed that classical and non-classical HLA genes contribute to the risk of rheumatic diseases. Integration of human disease genomics with biological, medical, and clinical databases should contribute to the elucidation of disease pathogenicity and novel drug discovery. Disease risk genes identified by large-scale genetic studies are considered to be promising resources for novel drug discovery, including drug repositioning and biomarker microRNA screening for rheumatoid arthritis.

Genetic and environmental risk factors for rheumatoid arthritis in a UK African ancestry population: the GENRA case-control study

Objectives

To evaluate whether genetic and environmental factors associated with RA in European and Asian ancestry populations are also associated with RA in African ancestry individuals.

Methods

A case-control study was undertaken in 197 RA cases and 868 controls of African ancestry (Black African, Black Caribbean or Black British ethnicity) from South London. Smoking and alcohol consumption data at RA diagnosis was captured. Genotyping was undertaken (Multi-Ethnic Genotyping Array) and human leukocyte antigen (HLA) alleles imputed. The following European/Asian RA susceptibility factors were tested: 99 genome-wide loci combined into a genetic risk score; HLA region [20 haplotypes; shared epitope (SE)]; smoking; and alcohol consumption. The SE was tested for its association with radiological erosions. Logistic regression models were used, including ancestry-informative principal components, to control for admixture.

Results

European/Asian susceptibility loci were associated with RA in African ancestry individuals. The genetic risk score provided an odds ratio (OR) for RA of 1.53 (95% CI: 1.31, 1.79; P = 1.3 × 10 - 7 ). HLA haplotype ORs in European and African ancestry individuals were highly correlated ( r = 0.83, 95% CI: 0.56, 0.94; P = 1.1 × 10 - 4 ). Ever-smoking increased (OR = 2.36, 95% CI: 1.46, 3.82; P = 4.6 × 10 - 4 ) and drinking alcohol reduced (OR = 0.34, 95% CI: 0.20, 0.56; P = 2.7 × 10 - 5 ) RA risk in African ancestry individuals. The SE was associated with erosions (OR = 2.61, 95% CI: 1.36, 5.01; P = 3.9 × 10 - 3 ).

Conclusion

Gene-environment RA risk factors identified in European/Asian ancestry populations are relevant in African ancestry individuals. As modern statistical methods facilitate analysing ancestrally diverse populations, future genetic studies should incorporate African ancestry individuals to ensure their implications for precision medicine are universally applicable.

HLA-DRB1 Amino Acid Positions 11/13, 71, and 74 Are Associated With Inflammation Level, Disease Activity, and the Health Assessment Questionnaire Score in Patients With Inflammatory Polyarthritis

Objective

Rheumatoid arthritis (RA) susceptibility HLA–DRB1 haplotypes based on amino acid positions 11/13, 71, and 74 predict radiographic damage. The mechanism of action is unknown, but it may be mediated by inflammation. We undertook this study to systematically investigate the effect of these amino acids on nonradiographic measures of disease activity/outcomes.

Methods

We tested the association of RA susceptibility HLA–DRB1 amino acids with the C‐reactive protein (CRP) level, the tender joint count (TJC), the swollen joint count (SJC), the Disease Activity Score in 28 joints (DAS28), and the Health Assessment Questionnaire (HAQ) score in the Norfolk Arthritis Register (NOAR) and Early Rheumatoid Arthritis Study (ERAS) cohorts. Longitudinal modeling of disease activity/outcomes was performed using generalized linear latent and mixed models. Mediation analysis was performed using directed acyclic graphs to investigate the paths from genetic factors to outcome.

Results

A total of 2,158 patients were available for analysis in the NOAR cohort. Valine at position 11 showed the strongest association with the CRP level (P = 2.21 × 10⁻⁶), the SJC (P = 7.51 × 10⁻⁶), and the DAS28 (P = 0.002); it was marginally associated with the HAQ score (P = 0.044) but not with the TJC. The same amino acid and haplotype risk hierarchy observed for susceptibility and radiographic severity was observed for the CRP level and nonradiographic measures of disease activity/outcome, apart from the TJC. The results were replicated in the ERAS cohort. The effect of valine at position 11 on the SJC was mainly mediated by anti–citrullinated protein antibody status, the effect of which was mainly mediated by inflammation; however, the effect of valine at position 11 was also independent of the CRP level (P = 1.6 × 10⁻⁴).

Conclusion

Genetic markers of RA susceptibility located within HLA–DRB1 determine the levels of clinical and systemic inflammation independently, and also determine all objective measures of disease activity and outcome.

The Relationship Between Mental Health, Disease Severity, and Genetic Risk for Depression in Early Rheumatoid Arthritis

OBJECTIVE

Reduced mental health (MH) is prevalent in rheumatoid arthritis (RA). Although longitudinal studies are limited, there is evidence that depression is associated with worse disease outcomes. We evaluated reciprocal relationships between MH, RA severity, and genetic risks for depression for 2 years in a well-characterized cohort of RA patients.

METHODS

We evaluated 520 early RA patients previously enrolled to two clinical trials. MH was measured using the short form-36 MH domain and mental component summary scores (MCS). MCS/MH associations over 2 years with disease activity (disease activity score on a 28-joint count), disability (health assessment questionnaire), pain visual analog scale scores, and a weighted genetic risk score for depression were tested using linear mixed-effects and regression models.

RESULTS

Poorer MH was associated with worse RA outcomes. Lower MCS scores (indicating worse MH) were seen in patients with a greater genetic risk for depression (weighted genetic risk score: coefficient = -1.21, p = .013). Lower baseline MCS was associated with lower 2-year improvements in disease activity score on a 28-joint count (coefficient = -0.02, p < .001), pain (coefficient = -0.33, p < .001), and health assessment questionnaire (coefficient = -0.01, p = .006). Baseline MCS was associated with changes in the swollen joint count (coefficient = -0.09, p < .001) and patient global assessment (coefficient = -0.28, p < .001) but not the tender joint count (p = .983) and erythrocyte sedimentation rate (p = .973). Only baseline pain visual analog scale (coefficient = -0.07, p = .002) was associated with 2-year changes in MCS.

CONCLUSIONS

Reduced baseline MH was associated with lower improvements in disease activity, disability, and pain for 2 years, supporting current national guidelines recommending screening for depression in RA. Pain had a bidirectional relationship with MH. Depression genetic risk had a significant association with MH.

Genetics of rheumatoid arthritis susceptibility, severity, and treatment response

A decade after the first genome-wide association study in rheumatoid arthritis (RA), a plethora of genetic association studies have been published on RA and its clinical or serological subtypes. We review the major milestones in the study of the genetic architecture of RA susceptibility, severity, and response to treatment. We set the scientific context necessary for non-geneticists to understand the potential clinical applications of human genetics and its significance for a stratified approach to the management of RA in the future.

Genome-wide association study identifies distinct genetic contributions to prognosis and susceptibility in Crohn's disease

For most immune-mediated diseases, the main determinant of patient well-being is not the diagnosis itself but instead the course that the disease takes over time (prognosis). Prognosis may vary substantially between patients for reasons that are poorly understood. Familial studies support a genetic contribution to prognosis, but little evidence has been found for a proposed association between prognosis and the burden of susceptibility variants. To better characterize how genetic variation influences disease prognosis, we performed a within-cases genome-wide association study in two cohorts of patients with Crohn's disease. We identified four genome-wide significant loci, none of which showed any association with disease susceptibility. Conversely, the aggregated effect of all 170 disease susceptibility loci was not associated with disease prognosis. Together, these data suggest that the genetic contribution to prognosis in Crohn's disease is largely independent of the contribution to disease susceptibility and point to a biology of prognosis that could provide new therapeutic opportunities.

Polymorphisms in STAT4, PTPN2, PSORS1C1 and TRAF3IP2 Genes Are Associated with the Response to TNF Inhibitors in Patients with Rheumatoid Arthritis

Objective

Rheumatoid Arthritis (RA) is a progressive autoimmune disease characterized by chronic joint inflammation and structural damage. Remission or at least low disease activity (LDA) represent potentially desirable goals of RA treatment. Single nucleotide polymorphisms (SNPs) in several genes might be useful for prediction of response to therapy. We aimed at exploring 4 SNPs in candidate genes (STAT4, PTPN2, PSORS1C1 and TRAF3IP2) in order to investigate their potential role in the response to therapy with tumor necrosis factor inhibitors (TNF-i) in RA patients.

Methods

In 171 RA patients we investigated the following SNPs: rs7574865 (STAT4), rs2233945 (PSORS1C1), rs7234029 (PTPN2) and rs33980500 (TRAF3IP2). Remission, LDA, and EULAR response were registered at 6 months and 2 years after initiation of first line TNF-i [Adalimumab (ADA) and Etanercept (ETN)].

Results

STAT4 variant allele was associated with the absence of a good/moderate EULAR response at 2 years of treatment in the whole RA group and in ETN treated patients. The PTPN2 SNP was associated with no good/moderate EULAR response at 6 months in ADA treated patients. Patients carrying PSORS1C1 variant allele did not reach LDA at 6 months in both the whole RA group and ETN treated patients. TRAF3IP2 variant allele was associated with the lack of LDA and remission achievement at 6 months in all RA cohort while an association with no EULAR response at 2 years of treatment occurred only in ETN treated patients.

Conclusions

For the first time, we reported that SNPs in STAT4, PTPN2, PSORS1C1, and TRAF3IP2 are associated with response to TNF-i treatment in RA patients; however, these findings should be validated in a larger population.

Rheumatoid Arthritis and Coronary Artery Disease: Genetic Analyses Do Not Support a Causal Relation

OBJECTIVE

Inflammatory diseases, specifically rheumatoid arthritis (RA), are assumed to increase the risk of coronary artery disease (CAD). More recently, multiple single-nucleotide polymorphisms (SNP) associated with RA risk were identified. If causal mechanisms affecting risks of RA and CAD are overlapping, risk alleles for RA might also increase the risk of CAD.

METHODS

Sixty-one SNP associating with RA in genome-wide significant analyses were tested for association with CAD in CARDIoGRAM (Coronary ARtery DIsease Genome wide Replication and Meta-analysis), a metaanalysis including genome-wide association data (22,233 CAD cases, 64,762 controls). In parallel, a set of SNP being associated with low-density lipoprotein cholesterol (LDL-C) was tested as a positive control.

RESULTS

Twenty-nine RA-associated SNP displayed a directionality-consistent association with CAD (OR range 1.002-1.073), whereas 32 RA-associated SNP were not associated with CAD (OR range 0.96-0.99 per RA risk-increasing allele). The proportion (48%) of directionality-consistent associated SNP equaled the proportion expected by chance (50%, p = 0.09). Of only 5 RA-associated SNP showing p values for CAD < 0.05, 4 loci (C5orf30, IL-6R, PTPN22, and RAD51B) showed directionality-consistent effects on CAD, and 1 (rs10774624, locus SH2B3) reached study-wide significance (p = 7.29E-06). By contrast, and as a proof of concept, 46 (74%) out of 62 LDL-C-associated SNP displayed a directionality-consistent association with CAD, a proportion that was significantly different from 50% (p = 5.9E-05).

CONCLUSION

We found no evidence that RA-associated SNP as a group are associated with CAD. Even though we were not able to study potential effects of all genetic variants individually, shared nongenetic factors may more plausibly explain the observed coincidence of the 2 conditions.

Abnormal PTPN11 enhancer methylation promotes rheumatoid arthritis fibroblast-like synoviocyte aggressiveness and joint inflammation

The PTPN11 gene, encoding the tyrosine phosphatase SHP-2, is overexpressed in rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLS) compared with osteoarthritis (OA) FLS and promotes RA FLS invasiveness. Here, we explored the molecular basis for PTPN11 overexpression in RA FLS and the role of SHP-2 in RA pathogenesis. Using computational methods, we identified a putative enhancer in PTPN11 intron 1, which contained a glucocorticoid receptor- binding (GR-binding) motif. This region displayed enhancer function in RA FLS and contained 2 hypermethylation sites in RA compared with OA FLS. RA FLS stimulation with the glucocorticoid dexamethasone induced GR binding to the enhancer and PTPN11 expression. Glucocorticoid responsiveness of PTPN11 was significantly higher in RA FLS than OA FLS and required the differentially methylated CpGs for full enhancer function. SHP-2 expression was enriched in the RA synovial lining, and heterozygous Ptpn11 deletion in radioresistant or innate immune cells attenuated K/BxN serum transfer arthritis in mice. Treatment with SHP-2 inhibitor 11a-1 reduced RA FLS migration and responsiveness to TNF and IL-1β stimulation and reduced arthritis severity in mice. Our findings demonstrate how abnormal epigenetic regulation of a pathogenic gene determines FLS behavior and demonstrate that targeting SHP-2 or the SHP-2 pathway could be a therapeutic strategy for RA.