PADI4 and HLA-DRB1 are genetic risks for radiographic progression in RA patients, independent of ACPA status: results from the IORRA cohort study

Association between COMMD1 gene polymorphism rs11125908 and rheumatoid arthritis in the Cuban population

OBJECTIVE

To evaluate the association of the rs11125908 polymorphism in the COMMD1 gene in the Cuban population with rheumatoid arthritis (RA).

METHODS

In this case-control study, 161 RA patients and 150 control subjects were genotyped for rs11125908 by the allele-specific polymerase chain reaction method. DNA sequencing was used to verify the assignation of the polymorphism. The odds ratios (OR) and their 95% confidence interval were calculated by logistic regression to determine the associations between genotypes and RA using the SNPStats software.

RESULTS

An association of the single nucleotide polymorphism with the disease was found in the overdominant model (p=0.025; OR=1.91) for the AG genotype. Our analyses revealed an association between rs11125908 and the subgroup of patients with swollen joints < median under the codominant model for AG (p=0.034; OR=2.30) and GG genotype (p=0.034; OR=0.82) and with the overdominant model (p=0.01; OR=2.38). The subgroup of patients with an age of onset lower than the mean and AG genotype showed an association in the overdominant model (p=0.027; OR=2.27). Disease activity score 28 with erythrocyte sedimentation rate and disease duration variables were not associated with the rs11125908 polymorphism.

CONCLUSIONS

rs11125908 was associated with RA and with the number of swollen joints and age of onset subgroup analyses. We provide concepts for treatments for RA, based on pharmacological management of COMMD1 expression.

Pathophysiology and stratification of treatment-resistant rheumatoid arthritis

Early diagnosis and timely therapeutic intervention are clinical challenges of rheumatoid arthritis (RA), especially for treatment-resistant or difficult-to-treat patients. Little is known about the immunological mechanisms involved in refractory RA. In this review, we summarize previous research findings on the immunological mechanisms of treatment-resistant RA. Genetic prediction of treatment-resistant RA is challenging. Patients with and without anti-cyclic citrullinated peptide autoantibodies are considered part of distinct subgroups, especially regarding long-term clinical prognosis and treatment responses. B cells, T cells and other immune cells and fibroblasts are of pathophysiological importance and are associated with treatment responses. Finally, we propose a new hypothesis that stratifies patients with RA into two subgroups with distinct immunological pathologies based on our recent immunomics analysis of RA. One RA subgroup with a favorable prognosis is characterized by increased interferon signaling. Another subgroup with a worse prognosis is characterized by enhanced acquired immune responses. Increases in dendritic cell precursors and diversified autoreactive anti-modified protein antibodies may have pathophysiological roles, especially in the latter subgroup. These findings that improve treatment response predictions might contribute to future precision medicine for RA.

Autocitrullination confers monocyte chemotactic properties to peptidylarginine deiminase 4

Peptidylarginine deiminase 4 (PAD4) contributes to the production of citrullinated proteins as autoantigens for anti-citrullinated protein antibodies (ACPAs) in rheumatoid arthritis (RA). PAD4 can also self-deiminate via autocitrullination. However, the role of this process in RA pathogenesis has not been elucidated. This study aimed to clarify PAD4 function before and after autocitrullination and identify citrullinated PAD4 in the synovial fluid of patients with RA. The autocitrullination of recombinant human PAD4 (rhPAD4) was catalyzed in vitro and determined using anti-modified citrulline immunoblotting. Monocyte chemotaxis was evaluated using Boyden chambers, and citrullinated rhPAD4's ability to induce arthritis was assessed in a C57BL/6J mouse model. Citrullinated PAD4 levels were measured in the synovial fluid of patients with RA and osteoarthritis using a novel enzyme-linked immunosorbent assay. Chemotactic findings showed that citrullinated rhPAD4 recruited monocytes in vitro, whereas unmodified rhPAD4 did not. Compared to unmodified rhPAD4, citrullinated rhPAD4 induced greater inflammation in mouse joints through monocyte migration. More citrullinated PAD4 was found in the synovial fluid of patients with RA than in those with osteoarthritis. Citrullinated PAD4 was even detected in ACPA-negative patients with RA. The autocitrullination of PAD4 amplified inflammatory arthritis through monocyte recruitment, suggesting an ACPA-independent role of PAD4 in RA pathogenesis.

Heavy Chain Constant Region Usage in Antibodies to Peptidylarginine Deiminase 4 as a Marker of Disease Subsets in Rheumatoid Arthritis

OBJECTIVE

The study of autoantibody isotypes in autoimmune diseases is useful for identifying clinically relevant endotypes. This study was undertaken to study the prevalence and clinical significance of different isotypes and IgG subclasses of anti-peptidylarginine deiminase 4 (anti-PAD4) autoantibodies in individuals with rheumatoid arthritis (RA).

METHODS

In 196 RA subjects and 64 healthy controls, anti-PAD4 antibody types were determined using enzyme-linked immunosorbent assay. We investigated associations between anti-PAD4 antibodies and clinical outcomes, and relevant features were confirmed in an independent RA cohort.

RESULTS

Anti-PAD4 IgG1, anti-PAD4 IgG2, anti-PAD4 IgG3, anti-PAD4 IgG4, anti-PAD4 IgA, and anti-PAD4 IgE antibodies were more frequent in RA patients than healthy controls (P < 0.001). Anti-PAD4 IgG1, anti-PAD4 IgG3, and anti-PAD4 IgE were associated with distinct clinical features. Anti-PAD4 IgG1 was predictive of progressive radiographic joint damage (odds ratio [OR] 4.88, P = 0.005), especially in RA patients without baseline joint damage (40% versus 0%, P = 0.003) or in those negative for anti-cyclic citrullinated peptide and/or rheumatoid factor (OR 32; P = 0.009). IgG1 was also associated with higher levels of C-reactive protein (P = 0.006) and interleukin-6 (P = 0.021). RA patients with anti-PAD4 IgG3 had higher baseline joint damage scores (median Sharp/van der Heijde score 13 versus 7, P = 0.046), while those with anti-PAD4 IgE had higher Disease Activity Score in 28 joints (median 4.0 versus 3.5, P = 0.025), more frequent rheumatoid nodules (31% versus 16%, P = 0.025), and more frequent interstitial lung disease (ground-glass opacification) (24% versus 9%, P = 0.014). Anti-PAD4 IgG1 antibody associations with joint damage were corroborated in an independent RA cohort.

CONCLUSION

Anti-PAD4 IgG1, anti-PAD4 IgG3, and anti-PAD4 IgE antibodies identify discrete disease subsets in RA, suggesting that heavy chain usage drives distinct effector mechanisms of anti-PAD4 antibodies in RA.

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.

Genetic effects of B3GNT2 on ankylosing spondylitis susceptibility and clinical manifestations in Taiwanese

BACKGROUND/PURPOSE

The intergenic SNP rs10865331 at 2p15 was identified as a major risk factor for ankylosing spondylitis (AS) susceptibility in genome-wide association studies (GWAS). B3GNT2 gene regulates polylactosamine synthesis is potentially functionally relevant to AS disease development. We investigated whether SNP rs10865331 and two B3GNT2 SNPs (rs11900673 and rs1136151) are associated with AS susceptibility and disease severity in Taiwanese.

METHODS

Distributions of genotypes, alleles, and haplotypes of three SNPs were compared between 1,472 AS patients and 2,117 healthy blood donors and among AS patients stratified by clinical characteristics.

RESULTS

The intergenic SNP rs10865331 was significantly associated with AS (P_FDR = 1.02E-05) in Taiwanese. In AS patients stratified by positivity of HLA-B27 and syndesmophyte formation, all three B3GNT2 locus SNPs (rs11900673, rs1136151, and rs10865331) were significantly associated with syndesmophyte formation among HLA-B27 positive AS patients. Haplotype analyses revealed that the "CTA" (rs11900673C/rs1136151T/rs10865331A) haplotype was significantly associated with AS susceptibility (Padj = 0.0177) and syndesmophyte formation (Padj = 0.016) in HLA-B27 positive patients. In contrast, "TCG" (rs11900673T/rs1136151C/rs10865331G) haplotype showed protection against AS development (Padj = 0.0005 for HLA-B27 positive and Padj = 0.004 for HLA-B27 negative, respectively) and syndesmophyte formation (Padj = 0.0017) in HLA-B27 positive patients. Furthermore, B3GNT2 mRNA expressions were negatively associated with erythrocyte sedimentation rate (ESR, P = 0.0103), C-reactive protein (CRP, P = 0.0353), Bath ankylosing spondylitis functional index (BASFI, P = 0.0171), and syndesmophyte formation (P = 0.0148).

CONCLUSION

Our data suggest that B3GNT2 gene may contribute to AS development and affect AS severity by interacting with HLA-B27 in Taiwanese.

Epidemiological Trends of Rheumatoid Arthritis and PADI4, PTPN22, and HLA-DRB9 Genes Distribution in the Kazakhstan Population

BACKGROUND: The prevalence of rheumatoid arthritis (RA) is 1% in the global population. The lack of epidemiological studies in developing countries makes it difficult to obtain a complete global epidemiological picture of RA. RA develops due to the interaction of multiple genetic and environmental factors, though the contribution of these factors to the various disease occurrence seen in different populations is unclear. AIM: The aim of our study was to analyze the dynamics of the general prevalence and incidence of RA among the population of Kazakhstan in 2017–2019 as well as to investigate the three most common single-nucleotide polymorphisms (SNP) of RA in the Kazakhstan population. METHODS: The analysis of statistical data on Form 12 “On the health of the people and the health care system” was carried out. Prevalence and incidence rates were calculated according to generally accepted rules. Demographic data for the Republic of Kazakhstan were obtained from the official website stat.gov.kz. Our study included 70 RA patients and 113 control subjects. Blood samples were collected and genotyped for peptidylarginine deiminase 4 (PADI4), protein tyrosine phosphatase 22, and human leukocyte antigen (HLA)-DRB9 SNPs by reverse transcription polymerase chain reaction. RESULTS: The prevalence of RA in Kazakhstan in 2017–2019 was 0.36–0.38%, with an incidence rate of 0.085–0.087%, which can be comparable to data of other countries in Central Asia. The allele and genotypes frequency analyses were carried out between patients and controls. The HLA-DRB9 showed significant association of the G allele odds ratio (OR) 1.96 (95% confidence interval [CI]: 1.252–3.081), p= 0.0025 and G/G genotype OR = 3.67 (95% CI: 1.58–8.54), p = 0.00162 with RA in our sample. Strong association between anti-citrullinated protein antibody (ACPA) profile and PADI4 (OR 12.19 [95% CI: 2.19–67.94], p = 0.00115) was found. CONCLUSION: There was an increase in RA prevalence with age among females and a higher crude prevalence and incidence of RA in the southern regions of Kazakhstan. HLA-DRB9 prevailed in Kazakhstani patients with RA, PADI4 showed association with ACPA-positive RA. Further studies on larger samples are required to confirm our obtained results.

Identifying and Validating Differentially Methylated Regions in Newly Diagnosed Patients with Graves' Disease

This research used combined bioinformatic methods to identify differentially methylated regions (DMRs) in newly diagnosed patients with Graves' disease (GD). Peripheral blood from six GD patients and controls was collected and methyl-DNA immunoprecipitation (MeDIP), and NimbleGen Human DNA Methylation 3 × 720 K promoter plus CpG island microarrays were further analyzed. DMRs were categorized into low-methylated genes and high-methylated genes, which were mapped into a protein-protein interaction (PPI) network constructed by a dataset. Then, six candidate genes were validated in an expanded population with 32 GD patients and 30 controls using bisulfite amplicon sequencing. Top 10 hub genes revealed by PPI analysis were CRHR1, CAMK2A, SERPINA1, RANBP9, ICAM1, ADRB2, KRTAP13-1, PTPRA, S100A2, and KPRP. Five CpG sites of CDKN2C (51436061), SERPINA1 (94856657), B3GNT2 (62422532 and 62422689), and IRS4 (107979477) were validated, having significantly different methylation levels between GD patients and controls. Based on gender stratification, nine significant CpG sites of CDKN2C (51436061), SERPINA1 (94855831), and B3GNT2 (62422301, 62422327, 62422356, 62422365, 62422374, 62422532, and 62422689) were detected between female GD patients and controls. The methylation level of 62422532 of B3GNT2 was significantly associated with levels of serum TGAb and TRAb. In addition, the methylation level of 62422689 of B3GNT2 showed significant correlation with the age of GD patients. In the analysis of prediction of transcription factor binding at specific CpG sites in B3GNT2 promoter region, paired box protein 5 (Pax-5) and CCAAT/enhancer-binding protein (C/EBP β) might be under the influence of methylation at CpG sites 62422365 and 62422532, respectively. CDKN2C, SERPINA1, IRS4, and especially B3GNT2 were potential aberrantly methylated genes related to GD. These findings might supply the latest information of DNA methylation in the GD disease.

A genome-wide association study identifying the SNPs predictive of rapid joint destruction in patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is a common chronic autoimmune disease leading to joint destruction. The aim of the present study was to identify the genomic factors predictive of susceptibility to joint destruction in patients with RA by performing a genome-wide association study of genetic variants, including single nucleotide polymorphisms (SNPs). The study sample included 228 patients with a diagnosis of RA in the past 5 years. Patients were classified into rapid (total Sharp score/years of RA, ≥50) and slow (total Sharp score/years of RA, <50) joint destruction groups for analysis. The association between the genome-wide SNP analysis and joint destruction was evaluated. The following SNPs were strongly associated with rapid radiographic joint destruction: rs2295926 (P<1x10^-7), belonging to the N-acetylgalactosaminyltransferase 12 (GALNT12) gene and rs11958855 (P<1x10^-6), belonging to the KCNN2 gene (associated with the potassium calcium-activated channel subfamily). The identification of genetic predictors of rapid joint destruction in RA (GALNT12 and KCNN2) may provide information regarding potential therapeutic targets, and this information may be used to assist in the management RA disease progression, thereby improving the functional outcomes for patients.

FEATURE SELECTION FOR GENERALIZED VARYING COEFFICIENT MIXED-EFFECT MODELS WITH APPLICATION TO OBESITY GWAS

Motivated by an empirical analysis of data from a genome-wide association study on obesity, measured by the body mass index (BMI), we propose a two-step gene-detection procedure for generalized varying coefficient mixed-effects models with ultrahigh dimensional covariates. The proposed procedure selects significant single nucleotide polymorphisms (SNPs) impacting the mean BMI trend, some of which have already been biologically proven to be "fat genes." The method also discovers SNPs that significantly influence the age-dependent variability of BMI. The proposed procedure takes into account individual variations of genetic effects and can also be directly applied to longitudinal data with continuous, binary or count responses. We employ Monte Carlo simulation studies to assess the performance of the proposed method and further carry out causal inference for the selected SNPs.

Joint Surgery in Tunisian Rheumatoid Arthritis Patients: Prevalence and Risk Factors

Objectives

This study aims to assess the prevalence of joint surgery in Tunisian patients with rheumatoid arthritis (RA) and to determine the risk factors of surgical treatment.

Patients and methods

This retrospective cross-sectional study was performed over a period of 15 years between January 2000 and December 2014 and included 500 Tunisian patients with RA (78 males, 422 females; mean age 53.4 years; range, 21 to 83 years). The prevalence of joint surgery indication was evaluated. Clinical, paraclinical and therapeutic characteristics of RA were compared according to the need of surgery.

Results

Female to male ratio was 5. The indication of joint surgery was noted in 59 patients (12%). Knee joint surgery was the most performed surgical procedure (56% of surgical treatment). A decrease in surgery prevalence from 30% in 2004 to 4% in 2013 was noted. Statistical study showed that factors associated with joint surgery were: delayed diagnosis (p=0.037), long RA duration (p=0.017), young onset of RA (p<0.001), presence of joint deformities (p=0.034), presence of osteoporosis (p=0.029), presence of antinuclear antibodies (p<0.001), combination therapy of methotrexate with other conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs) (p=0.001), short period of first medical treatment (p=0.012) and high erythrocyte sedimentation rate (ESR) (p=0.027). In multivariate analysis, three factors were independently related to the use of joint surgery: age at disease onset [odds ratio (OR): 2.799 95% confidence interval (CI): 1.49-5.22; p=0.01], high ESR level (OR: 2.807 95% CI: 1.5-5.24; p=0.01) and association of methotrexate with other csDMARDs (OR: 3.500 95% CI: 1.61-7.56; p=0.01).

Conclusion

Twelve percent of RA patients needed joint surgical treatment. Predictive factors of surgery were age at disease onset, high ESR level and association of methotrexate with other csDMARDs.

Cytokines (IL-15, IL-21, and IFN-γ) in rheumatoid arthritis: association with positivity to autoantibodies (RF, anti-CCP, anti-MCV, and anti-PADI4) and clinical activity

INTRODUCTION

Rheumatoid arthritis (RA) is an autoimmune disease characterized by synovial membrane damage and autoantibody production. RA is a heterogeneous disease, where cytokines such as IL-15, IL-21, and IFN-γ have been associated. However, their association with the autoantibodies has not been clearly described. The aim of this study was to evaluate the relationship between the cytokines IL-15, IL-21, and IFN-γ with the autoantibodies (RF, anti-CCP, anti-MCV, and anti-PADI4) in RA and disease activity.

METHODOLOGY

This study included 153 RA patients and 80 control subjects (CS). The levels of IL-15, IL-21, IFN-γ, anti-CCP, anti-MCV, and anti-PADI4 were quantified by ELISA, whereas RF was quantified by turbidimetry. The disease activity was evaluated by the indices disease activity score 28-erythrocyte sedimentation rate (DAS28-ESR), clinical disease activity index (CDAI), and simple disease activity index (SDAI).

RESULTS

The serum levels of IL-15, IL-21, and IFN-γ, and autoantibodies were increased in RA patients, compared with CS (p < 0.05). A correlation was found between IL-21 and anti-CCP and anti-MCV (p < 0.05). According to RA evolution, RF, anti-CCP, and anti-MCV had higher levels in early RA. In addition, increased levels of IL-21 were observed in RA seropositive patients (RF/anti-CCP/anti-MCV). The higher levels of both cytokines and autoantibodies were observed in moderate activity, evaluated by the three indices.

CONCLUSIONS

Our results suggest that the increased soluble levels of IL-15, IL-21, and IFN-γ are involved in the inflammatory network in RA. However, IL-21 serum levels are associated with higher titers of autoantibodies (RF, anti-CCP, and anti-MCV) and IL-15 with moderate activity. Key Points • IL-15, IL-21, and IFN-y are associated with the immunopathology of RA, but not significantly with the evolution of the disease. • RF, anti-CCP, and anti-MCV had higher levels in early than established RA. • IL-21 has an association with RF, anti-CCP, and anti-MCVand, for this reason, could be proposed as a disease biomarker. • Patients with activity moderate of disease showed higher levels of RF, anti-CCP, anti-MCV, and IL-15.

An Autoimmune Disease-Associated Risk Variant in the TNFAIP3 Gene Plays a Protective Role in Brucellosis That Is Mediated by the NF-κB Signaling Pathway

Naturally occurring functional variants (rs148314165 and rs200820567, collectively referred to as TT>A) reduce the expression of the tumor necrosis factor alpha-induced protein 3 (TNFAIP3) gene, a negative regulator of NF-κB signaling, and predispose individuals to autoimmune disease. In this analysis, we conducted a genetic association study of the TT>A variants in 1,209 controls and 150 patients with brucellosis, an infectious disease, and further assessed the role of the variants in brucellosis. Our data demonstrated that the TT>A variants were correlated with cases of brucellosis (P = 0.002; odds ratio [OR] = 0.34) and with individuals who had a positive serum agglutination test (SAT) result (titer of >1/160) (P = 4.2 × 10⁻⁶; OR = 0.23). A functional study demonstrated that brucellosis patients carrying the protective allele (A) showed significantly lower expression levels of the TNFAIP3 gene in their peripheral blood mononuclear cells and showed increased NF-κB signaling. Monocytes from individuals carrying the A allele that were stimulated with Brucella abortus had lower mRNA levels of TNFAIP3 and produced more interleukin-10 (IL-10), IL-6, and IL-1β than those from TT allele carriers. These data showed that autoimmune disease-associated risk variants, TT>A, of the TNFAIP3 locus play a protective role in the pathogenesis of brucellosis. Our findings suggest that a disruption of the normal function of the TNFAIP3 gene might serve as a therapeutic target for the treatment of brucellosis.

Hypoxia‑induced autophagy is inhibited by PADI4 knockdown, which promotes apoptosis of fibroblast‑like synoviocytes in rheumatoid arthritis

Impaired apoptosis of rheumatoid arthritis (RA)-fibroblast-like synoviocytes (FLS) is pivotal in the process of RA. Peptidyl arginine deiminase type IV (PADI4) is associated with autoantibody regulation via histone citrullination in RA. The present study aimed to investigate the role of PADI4 in the apoptosis of RA-FLS. FLS were isolated from patients with RA and a rat model. The effects of PADI4 on RA-FLS were investigated in vitro and in vivo. Hypoxia-induced autophagy was induced by 1% O₂ and was detected by immunohistochemical and immunofluorescence analysis; in addition, apoptosis was detected by flow cytometry. RA-FLS obtained from RA rat model exhibited significant proliferation under severe hypoxia conditions. Hypoxia also significantly induced autophagy and elevated the expression of PADI4. Subsequently, short hairpin RNA-mediated PADI4 knockdown was demonstrated to significantly inhibit hypoxia-induced autophagy and promote apoptosis in RA-FLS. The results of these in vitro and in vivo studies suggested that PADI4 may be closely associated with hypoxia-induced autophagy, and the inhibition of hypoxia-induced autophagy by PADI4 knockdown may contribute to an increase in the apoptosis of RA-FLS.

Joint damage is amplified in rheumatoid arthritis patients with positive thyroid autoantibodies

BACKGROUND

Autoimmune thyroid disease (AITD), which is characterized by an increased presence of thyroid autoantibodies (TAbs), such as antibodies against thyroid peroxidase (TPOAbs) and antibodies against thyroglobulin (TgAbs), has been reported to be associated with rheumatoid arthritis (RA) because AITD and RA both involve autoimmunity. However, few data are available on the incidence of TAbs in Chinese RA patients, and studies on the association between TAbs and joint damage as well as synovitis in RA patients remain sparse. Here, we aimed to evaluate the incidence of TAbs in a consecutive Chinese RA cohort and to investigate whether the elevated presence of TAbs is associated with joint damage and synovitis in RA patients.

METHODS

A total of 125 hospitalized RA patients were consecutively recruited. Clinical data and available synovial tissues were collected at baseline, and TAbs and thyroid function were detected by chemiluminescent immunoassay. Patients who tested positive for TPOAbs or TgAbs were classified as the TAbs-positive group, and patients who tested positive for neither TPOAbs nor TgAbs were recruited as the TAbs-negative group. Disease activity was assessed using DAS28-ESR (the disease activity score in 28 joints and including the erythrocyte sedimentation rate). X-ray assessment of the hand/wrist was performed according to the Sharp/van der Heijde-modified Sharp score (mTSS), and patients with an mTSS score >10 were defined as having radiographic joint damage (RJD). Serial tissue sections were stained immunohistochemically for CD3, CD15, CD20, CD34, CD38, and CD68, and synovitis were assessed according to Krenn's synovitis score.

RESULTS

A total of 44 (35%) patients were positive for either TPOAbs or TgAbs. Importantly, there was a significantly greater percentage of patients with RJD in the TAbs-positive group versus the TAbs-negative group (68% vs. 42%, p = 0.005). Compared with the TAbs-negative group, significantly more CD38-positive plasma cells infiltrated the TAbs-positive synovium, and a higher percentage of patients with high-grade synovitis were observed in the TAbs-positive group (5/8, 63% vs. 5/14, 36%). Moreover, RF positivity and disease activity indicators, including TJC28, DAS28-ESR, and CDAI, were significantly higher in the TAbs-positive group (all p < 0.05). Adjusted logistic regression analysis revealed that positive TAbs (OR 2.999, 95% CI [1.301-6.913]; p = 0.010) and disease duration (OR 1.013, 95% CI [1.006-1.019]; p < 0.001) were independently associated with RJD, and an odds ratio of 2.845 (95% CI [1.062-7.622]) was found for RJD in women with positive TAbs (n = 37) compared with those without TAbs (n = 59) (p = 0.038).

CONCLUSION

Our data showed that joint destruction was amplified in RA patients with an elevated presence of TAbs, which supports the importance and necessity of TAbs and thyroid function screening and monitoring in RA patient management in clinical practice.

Increased autophagy in fibroblast-like synoviocytes leads to immune enhancement potential in rheumatoid arthritis

The incidence of rheumatoid arthritis (RA) has been reported to be correlated with a disorder of immunregulation. Rheumatoid arthritis fibroblast-like synoviocytes (RA-FLSs) play an important role in regulating the local immune microenvironment. However, the potential mechanism of RA-FLS in regulating the immnue response is not clearly understood. In this study, we demonstrated that the expression of HIF-1α was significantly up-regulated in rheumatoid arthritis tissue which indicated that the hypoxia condition in the microenvironment. We also observed that RA-FLSs demonstrated the potential to up-regulate immune activation. Meanwhile, the level of autophagy increased in RA-FLSs compared with control group. Besides that, the expression of IL-6 was up-regulated not only in RA-FLSs but also in the fibroblasts that treated with hypoxia condition. Accordingly, we found that autophagy inhibitiors could effectively inhibit the immune activation function of RA-FLSs medicated by IL-6. Taken together, the results we demonstrated above indicated that the hypoxia microenvironment could effectively induce the incidence of autophagy and then lead to the immune activation function of RA-FLSs medicated by IL-6.

The role of genetic analysis for predicting outcome of rheumatoid arthritis

INTRODUCTION

Rheumatoid Arthritis (RA) varies from a mild to a severe, unremitting illness characterized by uncontrolled inflammation with consequent damage to cartilage and bone of joints. Individualized therapeutic approaches based on likely outcome would facilitate a personalized therapeutic approach. Areas covered: Genetics is known to contribute a significant component of the variability in RA outcome, estimated at 45-60%. A number of candidate gene studies have been associated with variability in radiologically assessed joint damage; however a more comprehensive genome wide analysis is required to more fully characterize the genetic basis of RA severity. Expert commentary: Genetic profiling of patient presenting with RA has the potential to aid stratification based on predicted prognosis, this would inform the clinical development of a personalized therapeutic approach. It will also result in the identification of novel mediators of tissue damage in RA.

Time-averaged disease activity fits better joint destruction in rheumatoid arthritis

Disease activity of rheumatoid arthritis (RA), evaluated as Disease Activity Score (DAS), is associated with joint destruction. Since joint destruction reflects the history of disease activities, we hypothesized that time-averaged disease activity would better correlate with joint destruction than one-time disease activity. We recruited RA patients in IORRA (n = 557) and KURAMA (n = 204) cohorts, and calculated time-averaged DAS28 to model a modified Sharp/van der Heijde score (SHS). We evaluated the fitting of the model using time-averaged DAS28 among 1000 models in which we randomly picked up one-time DAS28. We also used clinical disease activity index (CDAI) or data in the BeSt study (European population). After conditioning on autoantibody and disease duration, time-averaged DAS28 showed significant improvement of model fitting compared with one-time DAS28 in both cohorts (p = 0.001 and 0.034, respectively). Time-averaged CDAI also showed a better fit. Integration of multiple DAS fit SHS better in the BeSt study. A good fit of time-averaged DAS could be observed using five to six time points of DAS. In conclusion, time-averaged disease activity fits the joint destruction model better than one-time disease activity. Usage of time-averaged disease activity as a covariate would increase the power of studies to identify novel correlates of joint destruction.

NLRP1, PTPN22 and PADI4 gene polymorphisms and rheumatoid arthritis in ACPA-positive Singaporean Chinese

Studies have shown that the genetic risk factors for rheumatoid arthritis (RA) differ substantially between Asian and Caucasian populations. Even among Asian populations, the genetic contributions of NLRP1, PTPN22 and PADI4 have been controversial. Consequently, we sought to address these separate findings and determine whether any of these proposed risk variants are associated with RA susceptibility, onset, DAS activity and erosion in a Singaporean Chinese cohort. We genotyped five SNPs within NLRP1 (rs878329 and rs6502867), PTPN22 (rs2488457 and rs6665194), and PADI4 (rs2240340) in 500 anti-cyclic citrullinated peptide antibody-positive (ACPA) patients with RA and 500 healthy controls using TaqMan assays. The CC genotype of NLRP1 rs878329 and TT genotype of PADI4 rs2240340 were associated with RA susceptibility. The risk association of the T allele of PADI4 rs2240340 with RA was confirmed through a meta-analysis based on previous reports in Asian populations. The GG genotype of PTPN22 rs6665194 (-3508A>G) was associated with significantly reduced risk of RA. No significant association was found for NLRP1 rs6502867 T/C and PTPN22 rs2488457 G/C polymorphisms. None of the five SNPs was associated with RA's clinical features. This work supports the association of the T allele of PADI4 rs2240340 with RA in Asians. The roles of NLRP1 rs878329 G/C and PTPN22 rs6665194 A/G polymorphisms were demonstrated for the first time. We also propose rs6665194 to be a promising candidate for RA risk evaluation between ethnicities.

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.

Associations between C677T and A1298C polymorphisms of MTHFR and susceptibility to rheumatoid arthritis: a systematic review and meta-analysis

Methylenetetrahydrofolatereductase (MTHFR) is an important enzyme involved in folate metabolism and DNA synthesis. Although a number of studies have examined the association of the MTHFR C677T and A1298C polymorphisms with susceptibility to rheumatoid arthritis (RA), the conclusions are controversial. A comprehensive literature search using PubMed, Embase, the Cochrane Library, CNKI and Wanfang databases was conducted for relevant studies on the association between MTHFR polymorphisms and RA risk. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using fixed- and random-effect models. In total, 1854 cases and 1689 controls from 12 studies and 1525 cases and 1455 controls from 10 studies were included for the C677T and A1298C polymorphisms, respectively. Pooled results indicated that both C677T and A1298C polymorphisms were associated with RA susceptibility (C677T: TT vs. CC, OR = 1.31, 95% CI = 1.02-1.67, P = 0.032; TC vs. CC, OR = 1.32, 95% CI = 1.02-1.70, P = 0.032; TT + TC vs. CC, OR = 1.38, 95% CI = 1.07-1.78, P = 0.014; T vs. C, OR = 1.29, 95% CI = 1.06-1.57, P = 0.011; A1298C: CC vs. CA + AA: OR = 1.58, 95% CI = 1.20-2.06, P = 0.001). Further stratification based on ethnicity and geographic region indicated an association between the MTHFR C677T SNP and the risk of RA in Caucasian and patients in Africa. However, there is no evidence of significant association between A1298C polymorphism and RA risk in Caucasian or population in Africa. This meta-analysis indicates that MTHFR C677T and A1298C polymorphisms could be predictors of risk of RA and warrants validation in large and well-designed prospective studies.

PAD4: pathophysiology, current therapeutics and future perspective in rheumatoid arthritis

INTRODUCTION

Peptidyl arginine deiminase 4 (PAD4) is an enzyme that plays an important role in gene expression, turning out genetic code into functional products in the body. It is involved in a key post translational modification, which involves the conversion of arginine to citrulline. It regulates various processes such as apoptosis, innate immunity and pluripotency, while its dysregulation has a great impact on the genesis of various diseases. Over the last few years PAD4 has emerged as a potential therapeutic target for the treatment of rheumatoid arthritis (RA). Areas covered: In this review, we discuss the basic structure and function of PAD4, along with the role of altered PAD4 activity in the onset of RA and other maladies. We also elucidate the role of PAD4 variants in etiology of RA among several ethnic groups and the current pre-clinical inhibitors to regulate PAD4. Expert opinion: Citrullination has a crucial role in RA and several other disorders. Since PAD4 is an initiator of the citrullination, it is an important therapeutic target for inflammatory diseases. Therefore, an in depth knowledge of the roles and activity of PAD4 is required to explore more effective ways to conquer PAD4 related ailments, especially RA.

Recent Advances in Defining the Genetic Basis of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is the most common inflammatory arthritis and exhibits genetic overlap with other autoimmune and inflammatory disorders. Although predominant associations with the HLA-DRB1 locus have been known for decades, recent data have revealed additional insight into the likely causative variants within HLA-DRB1 as well as within other HLA loci that contribute to disease risk. In addition, more than 100 common variants in non-HLA loci have been implicated in disease susceptibility. Genetic factors are involved not only in the development of RA, but also with various disease subphenotypes, including production and circulating levels of autoantibodies and joint destruction. The major current challenge is to integrate these new data into a precise understanding of disease pathogenesis, including the critical cell types and molecular networks involved as well as interactions with environmental factors. We predict that delineating the functional effects of genetic variants is likely to drive new diagnostic and therapeutic approaches to the disease.

Decreased severity of experimental autoimmune arthritis in peptidylarginine deiminase type 4 knockout mice

Background

Peptidylarginine deiminase type 4 (PADI4) has been identified as a susceptibility gene for rheumatoid arthritis (RA) by genome-wide association studies. PADI4 is highly expressed in the bone marrow, macrophages, neutrophils, and monocytes. Peptidyl citrulline is an interesting molecule in RA because it is a target antigen for anti-citrullinated peptide antibodies, and only PADs (translated proteins from PADI genes) can provide peptidyl citrulline via the modification of protein substrates. The aim of this study was to evaluate the importance of the PADI4 gene in the progression of RA.

Methods

We generated Padi4 knockout (Padi4^−/−) DBA1J mice. The Padi4^−/− DBA1J and wild-type mice were immunized with bovine type II collagen (CII) to develop collagen-induced arthritis (CIA). The expression of various inflammatory cytokines and Padi genes in immune cells was detected by the real-time TaqMan assay. Cytokine concentrations in sera were measured by enzyme-linked immunosorbent assays. Localization of the PAD4 and PAD2 proteins was indicated by immunohistochemistry.

Results

We demonstrated that the clinical disease score was significantly decreased in the Padi4^−/− mice and Padi4 expression was induced by CII immunization. In the Padi4^−/− mice, serum anti-type II collagen (CII) immunoglobulin M (IgM), IgG, and inflammatory cytokine levels were significantly decreased compared with those in the wild-type mice. Padi2 expression was induced in the immune cells of the Padi4^−/− mice as a compensation for the defect in Padi4.

Conclusions

Padi4 affected disease severity in the CIA mice and was involved in the enhancement of the collagen-initiated inflammatory responses.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-016-1055-2) contains supplementary material, which is available to authorized users.

Rheumatoid Factor Is Associated With the Distribution of Hand Joint Destruction in Rheumatoid Arthritis

OBJECTIVE

Rheumatoid arthritis (RA) is a chronic disease leading to joint destruction. Although many studies have addressed factors potentially correlated with the speed of joint destruction, less attention has been paid to the distribution of joint destruction in patients with RA. In this study, destruction of the hand bones in patients with RA was classified into 2 anatomic subgroups, the fingers and the non-fingers, with the aim of analyzing which factors are associated with destruction of the finger joints.

METHODS

A total of 1,215 Japanese patients with RA were recruited from 2 different populations. The degree of joint destruction was assessed using the total modified Sharp/van der Heijde score (SHS) of radiographic joint damage. The SHS score of joint damage in the finger joints was used as the dependent variable, and the SHS score in the non-finger joints was used as a covariate. Age, sex, disease duration, smoking, C-reactive protein level, treatment for RA, and positivity for and levels of anti-citrullinated protein antibodies and rheumatoid factor (RF) were evaluated as candidate correlates. Overall effect sizes were assessed in a meta-analysis. In addition, associations observed in the Japanese patients were compared to those in a cohort of 157 Dutch RA patients in the BeSt study (a randomized, controlled trial involving 4 different strictly specified treatment strategies for early RA).

RESULTS

Not surprisingly, disease duration in Japanese patients with RA was associated with the finger SHS score (P ≤ 0.00037). Both positivity for and levels of RF showed significant associations with the finger SHS score after adjustment for covariates (P = 0.0022 and P = 8.1 × 10(-7) , respectively). These associations were also true in relation to the time-averaged finger SHS score. An association between RF positivity and the finger SHS score was also observed in Dutch patients with RA in the BeSt study (P = 0.049).

CONCLUSION

Positivity for and levels of RF are associated with finger joint destruction independent of non-finger joint destruction and other covariates. Our findings suggest that there are different mechanisms of joint destruction operating in the finger joints of patients with RA.

Genetic Variants Influencing Joint Damage in Mexican Americans and European Americans With Rheumatoid Arthritis

Joint destruction in rheumatoid arthritis (RA) is heritable, but knowledge on specific genetic determinants of joint damage in RA is limited. We have used the Immunochip array to examine whether genetic variants influence variation in joint damage in a cohort of Mexican Americans (MA) and European Americans (EA) with RA. We studied 720 MA and 424 EA patients with RA. Joint damage was quantified using a radiograph of both hands and wrists, scored using Sharp's technique. We conducted association analyses with the transformed Sharp score and the Immunochip single nucleotide polymorphism (SNP) data using PLINK. In MAs, 15 SNPs from chromosomes 1, 5, 9, 17 and 22 associated with joint damage yielded strong p-values (p < 1 × 10(-4) ). The strongest association with joint damage was observed with rs7216796, an intronic SNP located in the MAP3K14 gene, on chromosome 17 (β ± SE = -0.25 ± 0.05, p = 6.23 × 10(-6) ). In EAs, 28 SNPs from chromosomes 1, 4, 6, 9, and 21 showed associations with joint damage (p-value < 1 × 10(-4) ). The best association was observed on chromosome 9 with rs59902911 (β ± SE = 0.86 ± 0.17, p = 1.01 × 10(-6) ), a synonymous SNP within the CARD9 gene. We also observed suggestive evidence for some loci influencing joint damage in MAs and EAs. We identified two novel independent loci (MAP3K14 and CARD9) strongly associated with joint damage in MAs and EAs and a few shared loci showing suggestive evidence for association.

Peptidylarginine deiminase type 4 deficiency reduced arthritis severity in a glucose-6-phosphate isomerase-induced arthritis model

Peptidyl arginine deiminase 4 (PAD4) is an enzyme that is involved in protein citrullination, and is a target for anti-citrullinated peptide antibodies (ACPAs) in rheumatoid arthritis (RA). Genetic polymorphisms in the PADI4 gene encoding PAD4 are associated with RA susceptibility. We herein analyzed the roles of PADI4 in inflammatory arthritis using a glucose-6-phosphate isomerase (GPI)-induced arthritis (GIA) model in Padi4 knockout (KO) mice. Arthritis severity, serum anti-GPI antibody titers, and IL-6 concentrations were significantly reduced in Padi4 KO mice. The frequency of Th17 cells was decreased in GPI-immunized Padi4 KO mice, whereas WT and Padi4-deficient naïve CD4⁺ T cells displayed the same efficiencies for Th17 cell differentiation in vitro. In addition, the numbers of myeloid lineage cells were reduced with the increased expression of pro-apoptotic genes in GPI-immunized Padi4 KO mice. Furthermore, the survival of Padi4-deficient neutrophils was impaired in vitro. Our results suggest that PADI4 exacerbates arthritis with diverse immunological modifications.

Associations Between PADI4 Gene Polymorphisms and Rheumatoid Arthritis: An Updated Meta-analysis

BACKGROUND AND AIMS

Studies investigating the association between the peptidylarginine deiminase 4 (PADI4) gene polymorphisms and rheumatoid arthritis (RA) reported conflicting results. The aim of this meta-analysis was to assess the association between PADI4 gene polymorphisms and RA.

METHODS

A systematic literature search was conducted to identify relevant studies. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were used to estimate the strength of the association.

RESULTS

A total of 34 studies from 28 articles involving 19859 patients with RA and 25771 healthy controls were included. Significant association of PADI4-94G/A polymorphism and RA was observed (OR = 0.891, 95% CI = 0.833-0.954, p = 0.001) in the overall study population and in the Asian populations (OR = 0.824, 95% CI = 0.759-0.894, p = 0.000) respectively. For the -92C/G polymorphism, a significant association was observed (OR = 1.481, 95% CI = 1.166-1.882, p = 0.001) in Africans. For the -90C/T polymorphism, a significant association was observed (OR = 0.576, 95% CI = 0.381-0.872, p = 0.009) in the Latin American population. The pooled estimates for the other polymorphisms were not statistically significantly associated with RA (PADI4-104C/T, -89A/G, -96T/C).

CONCLUSIONS

This meta-analysis demonstrates that PADI4-94G/A polymorphism is associated with susceptibility to RA in the overall population and in the Asian population. The PADI4 -92C/G polymorphism confers susceptibility to RA in Africans and the PADI4-90C/T polymorphism was associated with RA in the Latin American population.

Genetic studies of rheumatoid arthritis

Rheumatoid arthritis (RA) is a common autoimmune disease that results in significant morbidity. As with other complex disorders, genome-wide association studies (GWASs) have greatly contributed to the current understanding of RA etiology. In this review, we describe the genetic configuration of RA as revealed primarily through GWASs and their meta-analyses. In addition, we discuss the pathologic mechanisms of RA as suggested by the findings of genetic and functional studies of individual RA-associated genes, including HLA-DRB1, PADI4, PTPN22, CCR6 and FCRL3, and the potential use of genetic information for RA treatment in clinical practice.

rs10865331 associated with susceptibility and disease severity of ankylosing spondylitis in a Taiwanese population

Ankylosing spondylitis (AS) is a highly familial rheumatic disorder and is considered as a chronic inflammatory disease. Genetic factors are involved in the pathogenesis of AS. To identify genes which render people susceptible to AS in a Taiwanese population, we selected six single-nucleotide polymorphisms (SNPs) from previous genome-wide association studies (GWASs) which were associated with AS in European descendants and Han Chinese. To assess whether the six SNPs contributed to AS susceptibility and severity in Taiwanese population, 475 AS patients fulfilling the modified New York Criteria and 527 healthy subjects were recruited. We found that rs10865331 was significantly associated with AS susceptibility and with Bath AS Function Index (BASFI). The AA and AG genotypes of rs10865331 were also significantly associated with a higher erythrocyte sedimentation rate. Our findings provided evidence that rs10865331 is associated AS susceptibility and with disease activity (BASFI) in a Taiwanese population.

SH3BP2 gain-of-function mutation exacerbates inflammation and bone loss in a murine collagen-induced arthritis model

Objective

SH3BP2 is a signaling adapter protein which regulates immune and skeletal systems. Gain-of-function mutations in SH3BP2 cause cherubism, characterized by jawbone destruction. This study was aimed to examine the role of SH3BP2 in inflammatory bone loss using a collagen-induced arthritis (CIA) model.

Methods

CIA was induced in wild-type (Sh3bp2^+/+) and heterozygous P416R SH3BP2 cherubism mutant knock-in (Sh3bp2^KI/+) mice, an SH3BP2 gain-of-function model. Severity of the arthritis was determined by assessing the paw swelling and histological analyses of the joints. Micro-CT analysis was used to determine the levels of bone loss. Inflammation and osteoclastogenesis in the joints were evaluated by quantitating the gene expression of inflammatory cytokines and osteoclast markers. Furthermore, involvement of the T- and B-cell responses was determined by draining lymph node cell culture and measurement of the serum anti-mouse type II collagen antibody levels, respectively. Finally, roles of the SH3BP2 mutation in macrophage activation and osteoclastogenesis were determined by evaluating the TNF-α production levels and osteoclast formation in bone marrow-derived M-CSF-dependent macrophage (BMM) cultures.

Results

Sh3bp2^KI/+ mice exhibited more severe inflammation and bone loss, accompanying an increased number of osteoclasts. The mRNA levels for TNF-α and osteoclast marker genes were higher in the joints of Sh3bp2^KI/+ mice. Lymph node cell culture showed that lymphocyte proliferation and IFN-γ and IL-17 production were comparable between Sh3bp2^+/+ and Sh3bp2^KI/+ cells. Serum anti-type II collagen antibody levels were comparable between Sh3bp2^+/+ and Sh3bp2^KI/+ mice. In vitro experiments showed that TNF-α production in Sh3bp2^KI/+ BMMs is elevated compared with Sh3bp2^+/+ BMMs and that RANKL-induced osteoclastogenesis is enhanced in Sh3bp2^KI/+ BMMs associated with increased NFATc1 nuclear localization.

Conclusion

Gain-of-function of SH3BP2 augments inflammation and bone loss in the CIA model through increased macrophage activation and osteoclast formation. Therefore, modulation of the SH3BP2 expression may have therapeutic potential for the treatment of rheumatoid arthritis.

Genetic basis of rheumatoid arthritis: a current review

Rheumatoid arthritis (RA) is one of the most common autoimmune diseases. As with other complex traits, genome-wide association studies (GWASs) have tremendously enhanced our understanding of the complex etiology of RA. In this review, we describe the genetic architecture of RA as determined through GWASs and meta-analyses. In addition, we discuss the pathologic mechanism of the disease by examining the combined findings of genetic and functional studies of individual RA-associated genes, including HLA-DRB1, PADI4, PTPN22, TNFAIP3, STAT4, and CCR6. Moreover, we briefly examine the potential use of genetic data in clinical practice in RA treatment, which represents a challenge in medical genetics in the post-GWAS era.

Peptidylarginine deiminase 4 contributes to tumor necrosis factor α-induced inflammatory arthritis

OBJECTIVE

Peptidylarginine deiminase 4 (PAD4) is a citrullinating enzyme that has multiple associations with inflammation. In rheumatoid arthritis, PAD4 and protein citrullination are increased in inflamed joints, and anti-citrullinated protein antibodies (ACPAs) form against citrullinated antigens are formed. ACPA immune complexes can deposit in the joint and induce the production of tumor necrosis factor α (TNFα), a critical inflammatory cytokine in the pathogenesis of rheumatoid arthritis. Further, in other settings, TNFα has been shown to induce PAD4 activity and modulate antibody formation. We undertook this study to investigate whether TNFα and PAD4 may synergistically exacerbate autoantibody production and inflammatory arthritis.

METHODS

To determine whether TNFα and PAD4 augment autoantibody production and inflammatory arthritis, we first used a multiplex assay to determine whether mice with chronic inflammatory arthritis due to overexpression of TNFα develop autoantibodies against native and citrullinated antigens. With TNF(+) PAD4(+/+) and TNF(+) PAD4(-/-) mice, we then compared serum autoantibody levels by multiplex array, lymphocyte activation by flow cytometry, total serum IgG levels by enzyme-linked immunosorbent assay, arthritis by clinical and histologic scoring, and systemic inflammation using microfluidic devices.

RESULTS

TNFα-overexpressing mice had increased levels of autoantibodies reactive against native and citrullinated antigens. PAD4(-/-) mice with TNFα-induced arthritis had lower levels of autoantibodies reactive against native and citrullinated antigens, decreased T cell activation and total IgG levels, and reduced inflammation and arthritis compared to PAD4(+/+) TNFα-overexpressing mice.

CONCLUSION

PAD4 mediates autoantibody production and inflammatory arthritis downstream of TNFα.

Predictive factors of response to biological disease modifying antirheumatic drugs: towards personalized medicine

Many therapies are now available for patients with rheumatoid arthritis (RA) who have an inadequate response to methotrexate including tumor necrosis factor inhibitors, abatacept, tocilizumab, and rituximab. Clinical response to drugs varies widely between individuals. A part of this variability is due to the characteristics of the patient such as age, gender, concomitant therapies, body mass index, or smoking status. Clinical response also depends on disease characteristics including disease activity and severity and presence of autoantibodies. Genetic background, cytokine levels, and immune cell phenotypes could also influence biological therapy response. This review summarizes the impact of all those parameters on response to biological therapies.

The Concise Guide to PHARMACOLOGY 2013/14: enzymes

The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. Enzymes are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ligand-gated ion channels, ion channels, nuclear hormone receptors, catalytic receptors and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates.