Fc receptor-like 1, 3, and 6 variants are associated with rheumatoid arthritis risk in the Chinese Han population

Background Rheumatoid arthritis (RA) is the most common autoimmune system diseases in our world. More studies in recent years have shown that FCRL gene polymorphisms is closely related to autoimmune diseases. It is suggested that genetic factors play a crucial role in the pathogenesis of this disease. In this study, we aimed to investigate the relationship between FCRL1 rs2050568, FCRL3 rs2317230 and FCRL6 rs58240276 polymorphisms and RA risk in the Chinese Han population. 506 with RA patients and 509 healthy controls were recruited in this study, and the single nucleotide polymorphisms (SNPs) was successfully genotyped using the Agena MassARRAY platform. Odds ratios (ORs) and 95% confidence intervals (95% CIs) after adjusting for age and gender were conducted to assess these SNPs polymorphisms and RA risk. The multifactor dimensionality reduction (MDR) method was conducted to analyze SNP-SNP interaction. Results Our results revealed that there no significant association was observed between the allele and genotype frequencies among these SNPs and RA risk (all p > 0.05). Straified analysis by age and gender, the results confirmed that FCRL1 rs2050568 T/T genotype enhanced the risk of RA in females (p = 0.014). The G/T - T/T genotype of FCRL3 rs2317230 was correlated with a decreased RA risk in males (p = 0.021). We also observed that the C/T-T/T genotype of FCRL6 rs58240276 was increased the risk of RA in the group at age > 54 years (p = 0.016). In addition, FCRL1 rs2050568-TT, FCRL6 rs58240276-TT and FCRL1 rs2050568-TT, FCRL3 rs2317230-TT, FCRL6 rs58240276-TT are the best models for multi-site MDR analysis (p < 0.05), and the two best models mentioned above and classes RA have the most significant correlation. Conclusions Our study demonstrated that FCRL1 rs2050568, FCRL3 rs2317230, and FCRL6 rs58240276 polymorphisms were correlated with RA susceptibility in the Chinese Han population.

The citrullinated/native index of autoantibodies against hnRNP-DL predicts an individual “window of treatment success” in RA patients

Background There is a need for biomarker to identify patients “at risk” for rheumatoid arthritis (risk-RA) and to better predict the therapeutic response and in this study we tested the hypothesis that novel native and citrullinated heterogeneous nuclear ribonucleoprotein (hnRNP)-DL autoantibodies could be possible biomarkers. Methods Using protein macroarray and ELISA, epitope recognition against hnRNP-DL was analysed in sera from different developed RA disease and diagnosed SLE patients. Toll-like receptor (TLR) 7/9 and myeloid differentiation primary response gene 88 (MyD88)-dependency were studied in sera from murine disease models. HnRNP-DL expression in cultivated cells and synovial tissue was analysed by indirect immunofluorescence, immunoblot and immunohistochemistry. Results HnRNP-DL was highly expressed in stress granules, citrullinated in the rheumatoid joint and targeted by autoantibodies either as native or citrullinated proteins in patient subsets with different developed RA disease. Structural citrullination dependent epitopes (SCEs) of hnRNP-DL were detected in 58% of the SLE patients although 98% of these sera were α-CCP-2-negative. To obtain a specific citrullinated signal value, we subtracted the native antibody value from the citrullinated signal. The citrullinated/native index of autoantibodies against hnRNP-DL (CNDL-Index) was identified as a new value for an “individual window of treatment success” in early RA and for the detection of RF IgM/α-CCP-2 seronegative RA patients (24–46%). Negative CNDL-index was found in SLE patients, risk-RA and early RA cohorts such as EIRA where the majority of these patients are DAS28-responders to methotrexate (MTX) treatment (87%). High positive CNDL-values were associated with more severe RA, shared epitope and parenchymal changes in the lung. Specifically, native α-hnRNP-DL is TLR7/9-dependent, associated with pain and ROC analysis revealed an association to initial MTX or etanercept treatment response, especially in seronegative RA patients. Conclusion CNDL-index defines people at risk to develop RA and the “window of treatment success” thereby closing the sensitivity gap in RA.

The impact of education inequality on rheumatoid arthritis risk is mediated by smoking and body mass index: Mendelian randomization study

Objective To estimate the causal relationship between educational attainment—as a proxy for socioeconomic inequality—and risk of RA, and quantify the roles of smoking and BMI as potential mediators. Methods Using the largest genome-wide association studies (GWAS), we performed a two-sample Mendelian randomization (MR) study of genetically predicted educational attainment (instrumented using 1265 variants from 766 345 individuals) and RA (14 361 cases, 43 923 controls). We used two-step MR to quantify the proportion of education’s effect on RA mediated by smoking exposure (as a composite index capturing duration, heaviness and cessation, using 124 variants from 462 690 individuals) and BMI (517 variants, 681 275 individuals), and multivariable MR to estimate proportion mediated by both factors combined. Results Each S.d. increase in educational attainment (4.2 years of schooling) was protective of RA (odds ratio 0.37; 95% CI: 0.31, 0.44). Higher educational attainment was also protective for smoking exposure (β = −0.25 S.d.; 95% CI: −0.26, −0.23) and BMI [β = −0.27 S.d. (∼1.3 kg/m2); 95% CI: −0.31, −0.24]. Smoking mediated 24% (95% CI: 13%, 35%) and BMI 17% (95% CI: 11%, 23%) of the total effect of education on RA. Combined, the two risk factors explained 47% (95% CI: 11%, 82%) of the total effect. Conclusion Higher educational attainment has a protective effect on RA risk. Interventions to reduce smoking and excess adiposity at a population level may reduce this risk, but a large proportion of education’s effect on RA remains unexplained. Further research into other risk factors that act as potentially modifiable mediators are required.

Adiponectin Associates with Rheumatoid Arthritis Risk in Overweight and Obesity Independently of Other Adipokines

We recently reported that increased serum adiponectin was associated with rheumatoid arthritis (RA) risk in subjects with obesity. We hereby aim to determine if other adipokines associate with RA risk and if the association between adiponectin and RA is independent of other adipokines. Two nested-case control studies were performed in two different cohorts: 82 participants of the Swedish Obese Subjects (SOS) study who developed RA during follow-up matched with 410 controls, and 88 matched pairs from the Medical Biobank of Northern Sweden. Baseline levels of circulating adipokines were measured using ELISA. In a multivariable analysis in the SOS cohort, higher adiponectin was associated with an increased risk of RA independently of other adipokines (OR for RA risk: 1.06, 95% CI: 1.01–1.12, p = 0.02). No association between leptin, resistin, and visfatin levels and the risk of RA was detected. In the cohort from the Medical Biobank of Northern Sweden, higher adiponectin was associated with an increased risk of RA only in participants with overweight/obesity (OR: 1.17, 95% CI: 1.01−1.36, p = 0.03), independently of other adipokines. Our results show that in individuals with overweight/obesity, higher circulating levels of adiponectin, but not leptin, resistin, or visfatin, were associated with an increased RA risk.

The CN-index of hnRNP-DL Predicts an Individual “Window of Treatment Success” in RA Patients

BackgroundThere is a need for biomarker to identify patients ‘at risk’ for rheumatoid arthritis (risk-RA) and to better predict the therapeutic response and in this study we tested the hypothesis that novel native and citrullinated heterogeneous nuclear ribonucleoprotein (hnRNP)-DL autoantibodies could be possible biomarkers.MethodsUsing Protein macroarray and ELISA, epitope recognition against hnRNP-DL was analysed in sera from different developed RA disease and diagnosed SLE patients. Toll-like receptor (TLR) 7/9 and myeloid differentiation primary response gene 88 (MyD88)-dependency were studied in sera from murine disease models. HnRNP-DL expression in cultivated cells and synovial tissue was analysed by indirect immunofluorescence, immunoblot and immunohistochemistry. ResultshnRNP-DL was highly expressed in stress granules, citrullinated in the rheumatoid joint and targeted by autoantibodies either as native or citrullinated proteins in patient subsets with different developed RA disease. Structural citrullination dependent epitopes (SCEs) of hnRNP-DL were detected in 58% of the SLE patients although 98% of these sera were α-CCP2-negative. To obtain a specific citrullinated signal value, we subtracted the native antibody value from the citrullinated signal. This CNDL (Citrullinated-Native-hnRNP-DL)-index identified and the bioinformatic value was explored, as a new value for an “individual window of treatment success” in early RA and for the detection of RF-IgM/α-CCP2 seronegative RA patients (24-46%). Negative CNDL-index was found in SLE patients, risk-RA- and early RA-cohorts such as EIRA where the majority of these patients are DAS28-responders to methotrexate (MTX) treatment (87%). High positive CNDL-values were associated with more severe RA, shared epitope and parenchymal changes in the lung. Specifically, native α-hnRNP-DL is TLR7/9-dependent, associated with pain and ROC-analysis revealed an association to initial MTX or etanercept treatment response, especially in seronegative RA patients.ConclusionCNDL-index defines patients is a possible biomarker for develop RA and the “window of treatment success” thereby potentially closing the sensitivity gap.

Characterization of Rheumatoid Arthritis Risk-Associated SNPs and Identification of Novel Therapeutic Sites Using an In-Silico Approach

Single-nucleotide polymorphisms (SNPs) are reported to be associated with many diseases, including autoimmune diseases. In rheumatoid arthritis (RA), about 152 SNPs are reported to account for ~15% of its heritability. These SNPs may result in the alteration of gene expression and may also affect the stability of mRNA, resulting in diseased protein. Therefore, in order to predict the underlying mechanism of these SNPs and identify novel therapeutic sites for the treatment of RA, several bioinformatics tools were used. The damaging effect of 23 non-synonymous SNPs on proteins using different tools suggested four SNPs, including rs2476601 in PTPN22, rs5029941 and rs2230926 in TNFAIP3, and rs34536443 in TYK2, to be the most damaging. In total, 42 of 76 RA-associated intronic SNPs were predicted to create or abolish potential splice sites. Moreover, the analysis of 11 RA-associated UTR SNPs indicated that only one SNP, rs1128334, located in 3′UTR of ETS1, caused functional pattern changes in BRD-BOX. For the identification of novel therapeutics sites to treat RA, extensive gene–gene interaction network interactive pathways were established, with the identification of 13 potential target sites for the development of RA drugs, including three novel target genes. The anticipated effect of these findings on RA pathogenesis may be further validated in both in vivo and in vitro studies.

Tuberculosis in biologic-naïve patients with rheumatoid arthritis - risk factors and tuberculosis characteristics

Objective To investigate risk factors and characteristics of active tuberculosis (TB) in biologics-naïve rheumatoid arthritis (RA) patients. Methods Population-based case-control study using the Swedish Rheumatology Quality Register, the National Patient Register and the Tuberculosis Register to identify RA cases with active TB and matched RA controls without TB 2001-2014. Clinical data were obtained from medical records. TB risk was estimated as adjusted (adj) odds ratios (OR) with 95% confidence intervals (CI) using univariate and multivariable logistic regression analyses. Results After validation of diagnoses, the study included 31 RA cases with TB, and 122 matched RA controls. All except three cases had reactivation of latent TB. Pulmonary TB dominated (84%). Ever use of methotrexate was not associated with increased TB risk (adj OR 0.8; 95% CI 0.3-2.0), whereas ever treatment with leflunomide (adj OR 6.0; 95% CI 1.5-24.6), azathioprine (adj OR 3.8; 95% CI 1.1-13.8) and prednisolone (adj OR 2.4 (95% CI 1.0-5.9) was. There were no significant differences of maximum dose of prednisolone, treatment duration with prednisolone before TB, or cumulative dose of prednisolone the year before TB diagnosis between cases and controls. Obstructive pulmonary disease was associated with an increased TB risk (adj OR 3.9; 95% CI 1.4-10.7). Conclusion Several RA-associated factors may contribute to the increased TB risk in biologics-naïve RA patients, making risk of TB activation difficult to predict in the individual patient. To further decrease TB in RA patients, the results suggest that screening for latent TB should also be considered in biologics-naïve patients.