Genetic variants in toll-like receptors are not associated with rheumatoid arthritis susceptibility or anti-tumour necrosis factor treatment outcome

Study of gene polymorphisms in Toll-like receptor 2 in patients with acute lymphoblastic leukemia

Objectives

Acute Lymphoblastic Leukemia (ALL) is a multifactorial disease that results from the interaction between multiple genetic factors. ALL is characterized by uncontrolled production of hematopoietic precursor cells of the lymphoid progenitors within the bone marrow. The development of hematological malignancies has been associated with malignant-like cells that express low levels of immunogenic surface molecules, thus, facilitating their escape from cellular antineoplastic immune responses. This risk may be partly influenced by variations in polymorphic genes that control immune function and regulation. Toll-like receptors (TLRs) are well known pattern recognition receptors playing key role in innate immune response. Abnormal expression and dysregulation of TLRs will provide an opportunity for cancer cells to escape from the immune system and enhance their proliferation and angiogenesis. Toll-like receptor 2 (TLR2) play an essential role in innate immunity. Single nucleotide polymorphisms (SNPs) are present in a number of TLR genes and have been associated with various disorders.

Methods

In this study, 265 subjects have been divided into two groups included 150 patients with ALL and115 healthy volunteers. All subjects were genotyped using TaqMan PCR techniques. In total, Five SNPs were statistically evaluated in the TLR2 (rs1898830 A/G, rs3804099 T/C, rs3804100 T/C, rs1339 T/C, and rs1337 C/G), which may influence the susceptibility of ALL. Minor allele frequency and genotype distribution were compared across the study groups, and the relative risk and differences between patients and controls were estimated. Moreover, the mRNA expression level was evaluated in patients with ALL and the matched healthy individuals by Real-Time Quantitative Reverse Transcription PCR (qRT-PCR).

Results

TLR2 rs1898830 A/G; rs3804099 T/C; rs3804100 T/C; rs1339 T/C, were significantly decrease the risk in our population, overall and for certain subtypes and ALL samples exhibited significant increase in the mRNA levels of TLR2.

Conclusions

This study shows that TLR2 could be an independent prognostic factor of ALL risks in the Saudi population. Suggesting that genetic variation in genes associated with an immune response may be important in the etiology of ALL. In addition, the results herein revealed that TLR2 overexpression is associated with ALL and has diverse biological significance in the context of the complex relationship between inflammation and cancer development. Therefore, these data could open further studies to explore the possible clinical relevance of TLRs as pathological markers for Leukemia and enhance the strategies regarding hematological malignancies prevention based on their gene expression.

Toll-Like Receptors Gene Polymorphisms in Autoimmune Disease

Toll-like receptors (TLRs) are important initiators of the immune response, both innate and acquired. Evidence suggests that gene polymorphisms within TLRs cause malfunctions of certain key TLR-related signaling pathways, which subsequently increases the risk of autoimmune diseases. We illustrate and discuss the current findings on the role of Toll-like receptor gene polymorphisms in numerous autoimmune diseases in this review, such as type 1 diabetes mellitus, Graves’ disease, rheumatoid arthritis, systemic lupus erythematosus and multiple sclerosis. The study of genetic variation in TLRs in different populations has shown a complex interaction between immunity and environmental factors. This interaction suggests that TLR polymorphisms affect the susceptibility to autoimmune diseases differently in various populations. The identification of Toll-like receptor gene polymorphisms can expand our understanding of the pathogenesis of autoimmune diseases, which will subsequently guide effective medical management and provide insight into prognosis and advanced treatments.

Machine Learning to Predict Anti-Tumor Necrosis Factor Drug Responses of Rheumatoid Arthritis Patients by Integrating Clinical and Genetic Markers

OBJECTIVE

Accurate prediction of treatment responses in rheumatoid arthritis (RA) patients can provide valuable information on effective drug selection. Anti-tumor necrosis factor (anti-TNF) drugs are an important second-line treatment after methotrexate, the classic first-line treatment for RA. However, patient heterogeneity hinders identification of predictive biomarkers and accurate modeling of anti-TNF drug responses. This study was undertaken to investigate the usefulness of machine learning to assist in developing predictive models for treatment response.

METHODS

Using data on patient demographics, baseline disease assessment, treatment, and single-nucleotide polymorphism (SNP) array from the Dialogue on Reverse Engineering Assessment and Methods (DREAM): Rheumatoid Arthritis Responder Challenge, we created a Gaussian process regression model to predict changes in the Disease Activity Score in 28 joints (DAS28) for the patients and to classify them into either the responder or the nonresponder group. This model was developed and cross-validated using data from 1,892 RA patients. It was evaluated using an independent data set from 680 patients. We examined the effectiveness of the similarity modeling and the contribution of individual features.

RESULTS

In the cross-validation tests, our method predicted changes in DAS28 (ΔDAS28), with a correlation coefficient of 0.405. It correctly classified responses from 78% of patients. In the independent test, this method achieved a Pearson's correlation coefficient of 0.393 in predicting ΔDAS28. Gaussian process regression effectively remapped the feature space and identified subpopulations that do not respond well to anti-TNF treatments. Genetic SNP biomarkers showed small contributions in the prediction when added to the clinical models. This was the best-performing model in the DREAM Challenge.

CONCLUSION

The model described here shows promise in guiding treatment decisions in clinical practice, based primarily on clinical profiles with additional genetic information.

Polymorphisms within Genes Involved in Regulation of the NF-κB Pathway in Patients with Rheumatoid Arthritis

Genes involved in regulation of the nuclear factor-κB (NF-κB)-pathway are suggested to play a role in pathogenesis of rheumatoid arthritis (RA). In the present study, genetic polymorphisms of TLR2, TLR4, TLR9 and NF-κB1 genes were investigated to assess their associations with RA susceptibility, progression and response to anti-TNF-α therapy. A group of 110 RA patients and 126 healthy individuals were genotyped for TLR2 (rs111200466), TLR4 (rs4986790, rs4986791), TLR9 (rs5743836, rs187084) and NF-κB1 (rs28362491) alleles. The presence of the TLR9 -1486 T variant (p < 0.0001) and its homozygosity (p < 0.0001) were found to be associated with disease susceptibility. The TLR9 -1237 C allele was associated with predisposition to RA in females only (p = 0.005). Moreover, the TLR4 rs4986791 G (rs4986790 T) alleles were more frequently detected among patients with the stage IV disease (p = 0.045), and were associated with more effective response to anti-TNF-α therapy (p = 0.012). More efficient response to anti-TNF-α treatment was also observed in patients with del within the NF-κB1 gene (p = 0.047), while for the TLR9 -1486 T homozygotes, the treatment was ineffective (p = 0.018). TLR polymorphisms affect disease susceptibility and response to therapy with TNF-α inhibitors in RA patients of Caucasian origin.

Systematic review and meta-analysis: pharmacogenetics of anti-TNF treatment response in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease that affects ~1% of the Caucasian population. Over the last decades, the availability of biological drugs targeting the proinflammatory cytokine tumour necrosis factor α, anti-TNF drugs, has improved the treatment of patients with RA. However, one-third of the patients do not respond to the treatment. We wanted to evaluate the status of pharmacogenomics of anti-TNF treatment. We performed a PubMed literature search and all studies reporting original data on associations between genetic variants and anti-TNF treatment response in RA patients were included and results evaluated by meta-analysis. In total, 25 single nucleotide polymorphisms were found to be associated with anti-TNF treatment response in RA (19 from genome-wide association studies and 6 from the meta-analyses), and these map to genes involved in T cell function, NFκB and TNF signalling pathways (including CTCN5, TEC, PTPRC, FCGR2A, NFKBIB, FCGR2A, IRAK3). Explorative prediction analyses found that biomarkers for clinical treatment selection are not yet available.

Polymorphism of TLR5 rs5744174 is associated with disease progression in Chinese patients with chronic HBV infection

Toll-like receptors (TLRs) play a crucial role in innate and adaptive immunity, protecting the host from viral pathogens. Studies have implicated that TLR5 is associated with various diseases such as autoimmune and inflammation related diseases. However, little is known about the relationship between TLR5 and hepatitis B virus (HBV) infection. We studied the effect of TLR5 gene polymorphisms on susceptibility to and disease progression of chronic hepatitis B (CHB) infection in Chinese. Blood samples were taken from 636 patients with CHB, HBV-related liver cirrhosis (LC) or hepatocellular carcinoma (HCC) and 273 controls. Polymorphisms of TLR5 (1775A>G rs2072493 and 1846T>C rs5744174) were analyzed by PCR-based sequencing. No difference in genotypic and allelic frequencies of TLR5 rs2072493 and rs5744174 was observed between patients and controls. Significant difference was found in frequency of TLR5 rs5744174 TT genotype between men with CHB and LC (p = 0.035). Frequency of TT genotype of TLR5 rs5744174 in patients positive for HBeAg was increased from 53.2% in patients with CHB to 74.1% in those with HCC (p = 0.024). Our results indicate that in Chinese genetic variation of TLR5 may be not a determinant of susceptibility to HBV-related diseases but may play a role in development of HBV-related severe liver diseases.

A functional variant of TLR10 modifies the activity of NFkB and may help predict a worse prognosis in patients with rheumatoid arthritis

Background

Toll-like receptor (TLR) family members are key players in inflammation. TLR10 has been poorly studied in chronic inflammatory disorders, and its clinical relevance in rheumatoid arthritis (RA) is as yet unknown. We aimed at identifying TLR10 variants within all coding regions of the gene in patients with RA as well as studying their functional and clinical significance.

Methods

TLR10 gene variants were studied by performing sequencing of 66 patients with RA and 30 control subjects. A selected variant, I473T, was then analyzed in 1654 patients and 1702 healthy control subjects. The capacity of this TLR10 variant to modify the transcriptional activity of nuclear factor kappa-light-chain-enhancer of activated B cells (NFkB) was determined by using a luciferase reporter assay and analyzing the expression of NFkB target genes by quantitative polymerase chain reaction. Differences between groups were analyzed by using the Mann-Whitney U test and the unpaired two-tailed Student’s t test.

Results

We detected ten missense variants in the TLR10 gene and focused on the I473T substitution based on allele frequencies and the predicted functional impact. I473T variant is not associated with susceptibility to RA, but it significantly correlates with erosive disease in patients seropositive for antibodies to citrullinated protein antigens (p = 0.017 in the total cohort and p = 0.0049 in female patients) and with a lower response to infliximab treatment as measured by the change in Disease Activity Score in 28 joints (p = 0.012) and by the European League Against Rheumatism criteria (p = 0.049). Functional studies showed that TLR10 reduced activation of the NFkB inflammatory pathway in hematopoietic cells, whereas the I473T variant lacked this inhibitory capacity. Consistently, after exposure to infliximab, cells expressing the I437T variant showed higher NFkB activity than cells carrying wild-type TLR10.

Conclusions

A TLR10 allelic variant, I473T, has impaired NFkB inhibitory activity and is highly associated with disease severity and low response to infliximab in patients with RA.

Microbiota and chronic inflammatory arthritis: an interwoven link

BACKGROUND

Only recently, the scientific community gained insights on the importance of the intestinal resident flora for the host's health and disease. Gut microbiota in fact plays a crucial role in modulating innate and acquired immune responses and thus interferes with the fragile balance inflammation versus tolerance.

MAIN BODY

Correlations between gut bacteria composition and the severity of inflammation have been studied in inflammatory bowel diseases. More recently similar alterations in the gut microbiota have been reported in patients with spondyloarthritis, whereas in rheumatoid arthritis an accumulating body of evidence evokes a pathogenic role for the altered oral microbiota in disease development and course. In the context of dysbiosis it is also important to remember that different environmental factors like stress, smoke and dietary components can induce strong bacterial changes and consequent exposure of the intestinal epithelium to a variety of different metabolites, many of which have an unknown function. In this perspective, and in complex disorders like autoimmune diseases, not only the genetic makeup, sex and immunologic context of the individual but also the structure of his microbial community should be taken into account.

CONCLUSIONS

Here we provide a review of the role of the microbiota in the onset, severity and progression of chronic inflammatory arthritis as well as its impact on the therapeutic management of these patients. Furthermore we point-out the complex interwoven link between gut-joint-brain and immune system by reviewing the most recent data on the literature on the importance of environmental factors such as diet, smoke and stress.

Evaluation of tool-like receptor-2 and 4 and interleukin-6 gene expressions in Turkish rheumatoid arthritis patients

Rheumatoid arthritis (RA) is a progressive inflammatory disease. Although the etiology and pathogenesis of RA are not known well, genetic and environmental factors are proposed to initiate an autoimmune process. We aimed to investigate mRNA expression levels of Toll-like receptor-2 (TLR-2), TLR-4, and interleukin-6 (IL-6) genes in RA disease. This study was conducted with 50 patients who were diagnosed with RA according to the American College of Rheumatology classification criteria for RA and 50 age-matched healthy control individuals who did not have any joint diseases and autoimmune diseases. We collected whole blood from all participants and analyzed expression of TLR-2, TLR-4, and IL-6 genes at mRNA level using real-time qPCR. TLR-2 expression was detected to increase 3.8-fold and IL-6 expression was detected to increase 6.8-fold in RA patients compared to healthy controls. No difference was found between patient and control groups with regard to TLR-4 expression. Overexpression of TLR-2 and IL-6 may be responsible for RA pathogenesis. Inhibition of both TLR and IL signaling pathways may prevent joint inflammation and destruction.

Genetic Variations in Pattern Recognition Receptor Loci Are Associated with Anti-TNF Response in Patients with Rheumatoid Arthritis

OBJECTIVES

To determine whether genetic variation within genes related to the Toll-like receptor, inflammasome and interferon-γ pathways contributes to the differences in treatment response to tumour necrosis factor inhibitors (anti-TNF) in patients with rheumatoid arthritis (RA).

METHODS

In a retrospective case-case study, we assessed 23 functional single nucleotide polymorphisms (SNPs) in 15 genes. We included 538 anti-TNF naïve Danish RA patients from the nationwide DANBIO database. Multivariable logistic regression analyses were performed to detect associations (p-value<0.05) between genotypes and European League Against Rheumatism (EULAR) treatment responses. False Discovery Rate corrections for multiple testing (q-value) and stratified analyses were performed to investigate association with individual therapies and IgM-rheumatoid factor (RF) status.

RESULTS

Six of twenty successfully genotyped polymorphisms were nominally associated with EULAR treatment response. Three of these were in weak to moderate linkage disequilibrium with polymorphisms previously reported associated with anti-TNF treatment response. TLR5(rs5744174) variant allele carriers (odds ratio(OR) = 1.7(1.1-2.5),p = 0.010,q = 0.46) and TLR1(rs4833095) homozygous variant carriers (OR = 2.8(1.1-7.4),p = 0.037,q = 0.46) had higher odds for a positive treatment response. NLRP3(rs10754558) variant allele carriers (odds ratio(OR) = 0.6(0.4-1.0),p = 0.045,q = 0.46) were more likely to have a negative treatment response. The association in TLR5(rs5744174) remained significant after correction for multiple comparisons among patients negative for RF (OR = 6.2(2.4-16.3),p = 0.0002,q = 0.024). No other association withstood correction for multiple testing. Post hoc analyses showed that change in Patient Global score on a visual analogue scale (VAS) and change in pain VAS were the main factors responsible for the association.

CONCLUSIONS

We reproduced previously reported associations between genetic variation in the TLR10/1/6 gene cluster, TLR5, and NLRP3 loci and response to anti-TNF treatment in RA. Changes in VAS pain and patient global scores were the main contributors to the association found for TLR5. Furthermore, we identified other candidate genes that require replication in independent cohorts.

Associations of toll-like receptor (TLR)-4 single nucleotide polymorphisms and rheumatoid arthritis disease progression: an observational cohort study

OBJECTIVE

To examine the associations of toll-like receptor (TLR)-4 single nucleotide polymorphisms (SNPs) with disease progression in rheumatoid arthritis (RA).

METHODS

A total of 1188 RA patients were genotyped for TLR4 SNPs (rs1927911, rs11536878, and rs4986790). Measures of disease activity were examined, including Disease Activity Score-28 (DAS28), Multidimensional Health Assessment Questionnaire (MD-HAQ), Clinical Disease Activity Index (CDAI), and Simplified Disease Activity Index (SDAI). Genetic associations with these longitudinal measures were examined using generalized estimating equations in both univariate and multivariate analyses. Analyses were then stratified by antigen specific anti-citrullinated peptide antibody (ACPA) status including antibody to citrullinated fibrinogen and citrullinated histone H2B.

RESULTS

Disease activity measures progressed less over time in the homozygous minor allele group of rs1927911 including DAS28 (p<0.001), CDAI (p=0.008), and MD-HAQ (p=0.015) in univariate analysis and DAS28, CDAI and SDAI in multivariate analysis. Disease activity progression among those homozygous for the minor allele tended to be lower in the groups with positive ACPA though major differences by autoantibody status were not identified. There were no associations of TLR4 rs11536878 and rs4986790 SNPs with RA disease activity progression.

CONCLUSIONS

In this population, TLR4 rs1927911 genotypes are associated with disease activity independent of other covariates.

Association of Toll like receptor Asp299Gly with rheumatoid arthritis risk: a systematic review of case-control studies and meta-analysis

OBJECTIVE

Rheumatoid arthritis (RA) is thought to be triggered by various genetic and environmental factors. Few human epidemiologic studies demonstrated that single nucleotide polymorphisms (SNPs) in Toll-like receptor (TLR) genes are associated with RA. We aimed to evaluate the effects of TLR polymorphisms on the risk of RA pathogenesis by using a meta-analysis approach.

METHODS

Following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines, a systematic search and meta-analysis of the literature was conducted. We screened the medical literature based on keywords search in MEDLINE and EMBASE 'Toll-like receptor', 'polymorphism', and rheumatoid arthritis. Meta-analyses were performed under the random-effects model by using: (1) recessive, (2) homozygous, (3) dominant, (4) codominant and allele contrast models.

RESULTS

A total of 3086 cases and 3756 controls in nine studies were included in the meta-analysis. Association between TLR4 Asp299Gly and RA risk was marginally significant [OR = 0.856 (95% CI, 0.716-1.022); P = 0.086] in the homozygous model. AA and GG homozygote genotypes tended to be significant protective factors against RA risk.

CONCLUSION

Our overall analyses indicated that TLR4 Asp299Gly polymorphism might contribute to RA pathogenesis.

Anti-TNF treatment response in rheumatoid arthritis patients is associated with genetic variation in the NLRP3-inflammasome

OBJECTIVE

Many patients with rheumatoid arthritis (RA) benefit from tumor necrosis factor-α blocking treatment (anti-TNF), but about one third do not respond. The objective of this study was to replicate and extend previously found associations between anti-TNF treatment response and genetic variation in the TNF-, NF-κB- and pattern recognition receptor signalling pathways.

METHODS

Forty-one single nucleotide polymorphisms (SNPs), including 34 functional, in 28 genes involved in inflammatory pathways were assessed in 538 anti-TNF naive Danish RA patients with clinical data. Multivariable logistic regression analyses were performed to test associations between genotypes and treatment response at 3-6 months using the European League Against Rheumatism (EULAR) response criterion. American College of Rheumatology treatment response (ACR50) and relative change in 28-joint disease activity score (relDAS28) were used as secondary outcomes. Subgroup analyses were stratified according to smoking status, type of anti-TNF drug and IgM-Rheumatoid Factor (IgM-RF) status. False discovery rate (FDR) controlling was used to adjust for multiple testing.

RESULTS

Statistically significant associations with EULAR response were found for two SNPs in NLRP3(rs4612666) (OR (odds ratio) for good/moderate response = 0.64 (95% confidence interval: 0.44-0.95), p = 0.025, q = 0.95) and INFG(rs2430561) (OR = 0.40 (0.21-0.76), p = 0.005, q = 0.18) and among IgM-RF positive patients for TNFRS1A(rs4149570) (0.59 (0.36-0.98), p = 0.040, q = 0.76). Current smokers who carried the NLRP3(rs4612666) variant allele were less likely to benefit from anti-TNF treatment (OR = 0.24 (0.10-0.56), p = 0.001, q = 0.04).

CONCLUSIONS

In a population of Danish RA patients, we confirm the NLRP3 gene as associated with EULAR anti-TNF response as previously reported. The NLRP3 variant (T) allele is associated with lower treatment response, in particular among current smokers. Furthermore, we find that a functional polymorphism in the interferon-γ gene is associated with anti-TNF response. All findings should be tested by replication in independent validation cohorts and augmented by assessing cytokine levels and activities of the relevant gene products.

Emerging role of endosomal toll-like receptors in rheumatoid arthritis

Toll-like receptors (TLRs) and their downstream signaling pathways have been comprehensively characterized in innate immunity. In addition to this function, these receptors have also been suggested to be involved in the pathogenesis of many autoimmune diseases, including rheumatoid arthritis (RA). Murine in vivo models and human in vitro tissue models of RA have provided a wealth of information on the potential activity of TLRs and components of the downstream signaling pathways. Whilst most early work investigated the cell surface TLRs, more recently the focus has moved to the endosomal TLRs 3, 7, 8, and 9. These receptors recognize self and foreign double-stranded RNA and single-stranded RNA and DNA. The development of therapeutics to inhibit the endosomal TLRs or components of their signaling cascades may represent a way to target inflammation upstream of cytokine production. This may allow for greater specificity than existing therapies including cytokine blockade. Here, we review the current information suggesting a role for the endosomal TLRs in RA pathogenesis and the efforts to target these receptors therapeutically.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Association of a functional polymorphism in the promoter region of TLR-3 with osteoarthritis: a two-stage case-control study

Recent studies have suggested that polymorphisms in toll-like receptor 9 (TLR-9), an endosomal TLR, are associated with knee osteoarthritis (OA). TLR-3, -7, and -8 are also found on the surface of endosomes and to investigate whether similar associations exist with polymorphisms in these TLR genes we performed a two-stage case-control study and genotyped 11 TLR single nucleotide polymorphisms (SNPs) in 823 OA cases and 594 healthy controls by polymerase chain reaction restriction fragment length polymorphism assays. Real-time PCR was performed to assess the functional expression of an identified promoter polymorphism in TLR-3 following dexamethasone stimulation of articular chondrocytes. An association between TLR-3 SNPs at rs3775296 and rs3775290 and OA was identified in both populations. In males the allelic frequencies of TLR-7 rs179010 and TLR-8 rs5744080 were significantly different between OA cases and healthy controls. The ATCA, CTCA, and CCTA haplotypes of TLR-3 were associated with OA susceptibility. A significant difference in TLR-3 gene expression following dexamethasone treatment was seen among the various genotypes of rs3775296 (p = 0.004). Our findings indicate that a SNP in the promoter region of TLR-3 is associated with elevated TLR-3 gene expression and susceptibility to knee OA in a Chinese Han population.

Genome-wide association study and gene expression analysis identifies CD84 as a predictor of response to etanercept therapy in rheumatoid arthritis

Anti-tumor necrosis factor alpha (anti-TNF) biologic therapy is a widely used treatment for rheumatoid arthritis (RA). It is unknown why some RA patients fail to respond adequately to anti-TNF therapy, which limits the development of clinical biomarkers to predict response or new drugs to target refractory cases. To understand the biological basis of response to anti-TNF therapy, we conducted a genome-wide association study (GWAS) meta-analysis of more than 2 million common variants in 2,706 RA patients from 13 different collections. Patients were treated with one of three anti-TNF medications: etanercept (n = 733), infliximab (n = 894), or adalimumab (n = 1,071). We identified a SNP (rs6427528) at the 1q23 locus that was associated with change in disease activity score (ΔDAS) in the etanercept subset of patients (P = 8 × 10(-8)), but not in the infliximab or adalimumab subsets (P>0.05). The SNP is predicted to disrupt transcription factor binding site motifs in the 3' UTR of an immune-related gene, CD84, and the allele associated with better response to etanercept was associated with higher CD84 gene expression in peripheral blood mononuclear cells (P = 1 × 10(-11) in 228 non-RA patients and P = 0.004 in 132 RA patients). Consistent with the genetic findings, higher CD84 gene expression correlated with lower cross-sectional DAS (P = 0.02, n = 210) and showed a non-significant trend for better ΔDAS in a subset of RA patients with gene expression data (n = 31, etanercept-treated). A small, multi-ethnic replication showed a non-significant trend towards an association among etanercept-treated RA patients of Portuguese ancestry (n = 139, P = 0.4), but no association among patients of Japanese ancestry (n = 151, P = 0.8). Our study demonstrates that an allele associated with response to etanercept therapy is also associated with CD84 gene expression, and further that CD84 expression correlates with disease activity. These findings support a model in which CD84 genotypes and/or expression may serve as a useful biomarker for response to etanercept treatment in RA patients of European ancestry.

Toll-like receptor polymorphisms and rheumatoid arthritis: a systematic review

The aim of this study was to determine whether toll-like receptor (TLR) polymorphisms confer susceptibility to rheumatoid arthritis (RA) and influence the clinical characteristics of RA. The authors conducted a systematic review on associations between TLR polymorphisms and RA susceptibility and clinical findings. Meta-analysis was performed if at least three comparisons of an issue were available. A total of 14 studies were included in this systematic review, which included European and Asian studies. Meta-analysis of five European studies showed no association between the TLR4 Asp299Gly (rs4986790) polymorphism and RA (OR for the minor allele = 0.907, 95% CI = 0.755-1.088, p = 0.291). Furthermore, none of these studies found any association between the polymorphism and clinical characteristics. A significant difference between TLR9 rs187084 allele frequencies in RA patients and controls was found in one Turkish study (p = 0.003), and a moderate association between RF positivity and TLR8 rs5741883 was found in an European study (p = 0.001). The numbers of guanine-thymine [(GT)n] repeats in intron II of the TLR2 gene were found a significantly higher S-allele frequency in Korean patients with RA than in controls (30.3 vs. 23.0 %, p = 0.03). This meta-analysis shows lack of an association between the TLR4 Asp299Gly polymorphism and RA. However, our finding suggests the possibility that TLR polymorphisms are associated with the development and clinical characteristics of RA. Because of a paucity of data of the TLR polymorphisms, case-control studies are required to determine whether TLR2, 4, 8, 9 polymorphisms contribute to RA susceptibility or severity in more than 2,000 patients and controls.

NF-κB and Rheumatoid Arthritis: Will Understanding Genetic Risk Lead to a Therapeutic Reward?

NF-κB has long been known to play an important role in autoimmune diseases such as rheumatoid arthritis (RA). Indeed, as our understanding of how NF-κB is utilized has increased, we have been hard put to find a process not associated with this transcription factor family in some way. However, new data originating, in part, from genome-wide association studies have demonstrated that very specific alterations in components of the NF-κB pathway are sufficient to confer increased risk of developing disease. Here we review the data which have identified specific components of the NF-κB pathway, and consider what is known of their mechanisms of action and how these mechanisms might play into the disease process. In addition, the use of genetic information to predict RA is considered.

Mavrilimumab, a human monoclonal antibody targeting GM-CSF receptor-α, in subjects with rheumatoid arthritis: a randomised, double-blind, placebo-controlled, phase I, first-in-human study

Objective

To evaluate the safety, tolerability, pharmacokinetic and pharmacodynamic profiles of mavrilimumab, a human monoclonal antibody targeting the granulocyte-macrophage colony-stimulating factor receptor-α, in subjects with rheumatoid arthritis (RA).

Methods

A randomised, double-blind, placebo-controlled, dose-escalating phase I study in subjects with RA who received stable methotrexate treatment for ≥3 months before enrolment. Subjects received single intravenous escalating doses of mavrilimumab (0.01–10.0 mg/kg) or placebo.

Results

32 subjects were enrolled in this study (1 unblinded subject at 0.01 mg/kg and another at 0.03 mg/kg were followed by five sequential double-blinded cohorts, n=6 each, treated with 0.1, 0.3, 1.0, 3.0 and 10.0 mg/kg, respectively). Adverse events were mild or moderate and were reported with similar frequency across all treatment cohorts. One subject (10.0 mg/kg) experienced moderate face and neck urticaria during infusion that resolved with symptomatic treatment. Systemic clearance of mavrilimumab approached that of endogenous IgG at doses >1.0 mg/kg; pharmacodynamic activity was confirmed in the 1.0 and 3.0 mg/kg cohorts by suppression of suppressor of cytokine signalling 3 mRNA transcripts. In exploratory analyses, reductions of acute phase reactants were observed in subjects with elevated C-reactive protein (>5 mg/l) and erythrocyte sedimentation rate (≥20.0 mm/h) at baseline. No significant change in Disease Activity Score 28-joint assessment (DAS28) was seen in any of the cohorts. In mavrilimumab-treated subjects (n=15) with baseline DAS28 >3.2, mean disease activity (DAS28) was significantly reduced at 4 weeks.

Conclusion

In this first-in-human study, mavrilimumab showed preliminary evidence of pharmacodynamic activity. Importantly, the safety and pharmacokinetic profiles of mavrilimumab support further clinical studies in RA.

Trial registration number: NCT00771420.