Early monitoring of infliximab serum trough levels predicts long-term therapy failure in patients with axial spondyloarthritis.

OBJECTIVE: To evaluate whether serum infliximab trough levels (ITL) during the early stages of treatment are predictive of long-term clinical failure in patients with axial spondyloarthritis (axSpA). METHODS: Longitudinal observational study involving 81 patients with axSpA monitored during infliximab therapy. Serum ITL were measured before starting infliximab treatment and at weeks 2 (W2), W6 and W12 of treatment. Disease activity was assessed by Ankylosing Spondylitis Disease Activity Score (ASDAS) at baseline, W24 and W52, and every 6 months thereafter until treatment discontinuation, regardless of the reason. Non-clinically important improvement was defined by ΔASDAS<1.1. The association between serum levels during the early stages and clinical outcomes (non-clinically important improvement at W52, drug survival and drop-out due to secondary inefficacy) was investigated through logistic regression models and Kaplan Meier curves. Receiver operating characteristic (ROC) curves were employed to determine the best cut-off for serum ITL. RESULTS: Out of the 81 patients, 45 (56%) did not achieve clinical improvement at W52. These patients had lower serum ITL at W12 compared to those who improved: ITL [median (IQR)]: 4.1(0.9-8.3) µg/mL vs 7.1 (4.3-11.3) µg/mL, respectively;p = 0.007). ITL<6.7 µg/mL at W12 was significantly associated with: i) not achieving clinical improvement at W52 (OR: 2.3; 95%CI: 1.3-3.9); ii) shorter drug survival (5.0 years (95% CI 3.8-6.2) vs 7.0 years (95% CI 4.8-6.9; p = 0.04), and iii) higher drop-out rates due to secondary inefficacy (OR: 3.5; 95% CI: 1.2-10.2). CONCLUSION: Low serum ITL at W12 were associated with long-term clinical failure in patients with axSpA, due to secondary inefficacy.

Serum tocilizumab trough concentration can be used to monitor systemic IL-6 receptor blockade in patients with rheumatoid arthritis: a prospective observational cohort study.

OBJECTIVES: To investigate the pharmacokinetics (PK) and dynamics of tocilizumab (TCZ) in daily practice. METHOD: An observational study of 66 consecutive RA patients treated with TCZ 8 mg/kg once every 4 weeks intravenously, monitored for 24 weeks. Spearman's rank test was used to investigate the correlation between TCZ concentration and C-reactive protein (CRP). Clinical improvement was assessed at week 24 using the Disease Activity Score in 28 joints (DAS28) compared to baseline, and its relationship with TCZ concentration was investigated using linear regression analyses. TCZ trough concentrations and anti-drug antibodies were measured using an enzyme-linked immunosorbent assay (ELISA) and antigen binding test, respectively. RESULTS: At baseline, 26 patients (39.4%) had a CRP level above 10 mg/L with a median (interquartile range, IQR) of 37.7 (21.9-49.7) mg/L. A TCZ concentration above 1 mg/L was sufficient to normalize CRP levels. Spearman's rank test showed a correlation coefficient of -0.460 (p < 0.0001). The TCZ concentration varied widely, with concentrations < 1 mg/L in 17-31% of patients, depending on the time point of measurement. Anti-TCZ antibodies were detected in one sample. Linear regression analyses showed a coefficient of 0.080 with a 95% confidence interval (CI) of 0.039-0.113 (p < 0.001) for the association between TCZ concentration and ΔDAS28. No confounders were identified. CONCLUSIONS: The TCZ standard regimen results in a wide variety of serum TCZ trough concentrations; this is mostly due to target binding and to a lesser extent to immunogenicity. The majority of patients obtained TCZ concentrations > 1 mg/L, which is sufficient for CRP normalization. Therefore, dose taper strategies might be possible in a substantial proportion of patients.

Replication of PTPRC as genetic biomarker of response to TNF inhibitors in patients with rheumatoid arthritis.

Genetic biomarkers could be useful for orienting treatment of patients with rheumatoid arthritis (RA), but none has been convincingly validated yet. Putative biomarkers include 14 single nucleotide polymorphisms that have shown association with response to TNF inhibitors (TNFi) in candidate gene studies and that we assayed here in 755 RA patients. Three of them, in the PTPRC, IL10 and CHUK genes, were significantly associated with response to TNFi. The most significant result was obtained with rs10919563 in PTPRC, which is a confirmed RA susceptibility locus. Its RA risk allele was associated with improved response (B=0.33, P=0.006). This is the second independent replication of this biomarker (P=9.08 × 10(-8) in the combined 3003 RA patients). In this way, PTPRC has become the most replicated genetic biomarker of response to TNFi. In addition, the positive but weaker replication of IL10 and CHUK should stimulate further validation studies.

The 11q23.3 genomic region-rs964184-is associated with cardiovascular disease in patients with rheumatoid arthritis.

Rheumatoid arthritis (RA) is an inflammatory disease associated with high risk of cardiovascular (CV) events. Recently, the rs964184 polymorphism has been associated with coronary artery disease in nonrheumatic Caucasian individuals. 2160 Spanish RA patients were genotyped for the rs964184 polymorphism. Sex, age at diagnosis and traditional CV risk factors (diabetes mellitus, dyslipidemia and smoking habit) were associated with increased risk of CV events. Interestingly, RA patients carrying the rs964184 GG genotype had significantly higher risk of CV events than those with CC genotype [hazard ratio (HR) = 2.91, 95% confidence interval (CI): 1.36-6.26, P = 0.006] after adjusting the results for sex, age at diagnosis and traditional CV risk factors. Our results indicate that rs964184 polymorphism is associated with CV disease in RA.

Single-nucleotide polymorphisms at the 9p21.3 genomic region not associated with the risk of cardiovascular disease in patients with rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic polygenic inflammatory disease associated with accelerated atherosclerosis and high risk of cardiovascular disease (CVD). In this study, we evaluated the potential association of 9p21.3 single-nucleotide polymorphisms (SNPs) - previously linked to coronary artery disease - and CVD risk in 2001 Spanish RA patients genotyped for 9p21.3 SNPs using TaqMan™ assays. Carotid intima media thickness (cIMT) and presence of carotid plaques were also analyzed. Cox regression model did not disclose significant differences between patients who experienced CVD and those who did not. Neither association was found between cIMT or carotid plaques and SNPs allele distribution. In conclusion, results do not support a role of rs10116277 or rs1537375 SNPs in CVD risk in Spanish RA patients.

The C677T polymorphism in the MTHFR gene is associated with the toxicity of methotrexate in a Spanish rheumatoid arthritis population.

OBJECTIVE: Methotrexate (MTX) is the first-choice drug for the treatment of rheumatoid arthritis (RA) patients. However, 30% of RA patients discontinue therapy within 1 year, usually because of adverse effects. Previous studies have reported conflicting results on the association of polymorphisms in the MTHFR gene with the toxicity of MTX in RA. The aim of this study was to assess the involvement of the C677T and A1298C polymorphisms in the MTHFR gene in the toxicity of MTX in a Spanish RA population. METHODS: The study included retrospectively 468 Spanish RA patients treated with MTX. Single nucleotide polymorphism (SNP) genotyping was performed using the oligonucleotide microarray technique. Allele and genotype association analyses with regard to MTX toxicity and a haplotype association test were also performed. RESULTS: Eighty-four out of the 468 patients (18%) had to discontinue therapy due to adverse effects or MTX toxicity. The C677T polymorphism (rs1801133) was associated with increased MTX toxicity [odds ratio (OR) 1.42, 95% confidence interval (CI) 1.01-1.98, p = 0.0428], and the strongest association was shown in the recessive model (OR 1.95, 95% CI 1.08-3.53, p = 0.0246). The A1298C polymorphism (rs1801131) was not associated with increased MTX toxicity (OR 0.94, 95% CI 0.65-1.38, p = 0.761). A borderline significant risk haplotype was found: 677T-1298A (OR 1.40, 95% CI 1.00-1.96, p = 0.0518). CONCLUSION: These results demonstrate that the C677T polymorphism in the MTHFR gene is associated with MTX toxicity in a Spanish RA population.

Lack of association of IL6R rs2228145 and IL6ST/gp130 rs2228044 gene polymorphisms with cardiovascular disease in patients with rheumatoid arthritis.

Interleukin-6 (IL-6) is a key mediator of inflammation in rheumatoid arthritis (RA) and its actions may be controlled by the IL-6 receptor (IL-6R). IL-6 transducer (IL-6ST/ gp130) is the signal transducing subunit of the IL-6R. We assessed the influence of the IL6R and the IL6ST/gp130 genes in the risk of cardiovascular (CV) disease in RA. For this purpose, 1250 Spanish patients with RA were genotyped for the IL6R rs2228145 and IL6ST/gp130 rs2228044 functional gene polymorphisms. Patients were stratified according to the presence or absence of CV events. Also, a subgroup of patients without CV events was assessed for the presence of subclinical atherosclerosis using two surrogate markers of atherosclerosis (flow-mediated endothelium-dependent vasodilatation and carotid intima-media thickness). No significant differences in the genotype and allele frequencies for both gene polymorphisms between patients with and without CV events were observed. It was also the case when values of surrogate markers of atherosclerosis were compared according to IL6R and IL6ST genotype frequencies. In conclusion, our results do not confirm an association of IL6R rs2228145 and IL6ST/gp130 rs2228044 polymorphisms with CV disease in RA.

Lack of association of PTPN22, STAT4 and TRAF1/C5 gene polymorphisms with cardiovascular risk in rheumatoid arthritis.

OBJECTIVES: To determine whether the PTPN22, STAT4 and TRAF1/C5 gene polymorphisms may be implicated in the development of cardiovascular (CV) events and subclinical atherosclerosis manifested by the presence of endothelial dysfunction or increased carotid intima-media thickness (IMT) in a series of Spanish patients with rheumatoid arthritis (RA). METHODS: Six hundred and twelve patients fulfilling the 1987 American College of Rheumatology classification criteria for RA, seen at the rheumatology outpatient clinics of Hospital Xeral-Calde, Lugo, and Hospital San Carlos, Madrid, were studied. Patients were genotyped using predesigned TaqMan single nucleotide polymorphism genotyping assays. Moreover, between March and December 2007, a subgroup of unselected RA patients with no history of CV events was studied for the presence of subclinical atherosclerosis by the assessment of the endothelial function (n=126) and the carotid artery IMT (n=110) by ultrasonography studies. RESULTS: No significant differences in the allele or genotype frequencies for the PTPN22, STAT4 and TRAF1/C5 gene polymorphisms between RA patients with or without CV events were found. It was also the case when we analysed the potential influence of the genotypes in the presence of endothelial dysfunction or increased carotid artery IMT of patients with RA. CONCLUSIONS: Our results do not show that the PTPN22, STAT4 and TRAF1/C5 gene polymorphisms may confer a direct risk of CV disease in patients with RA.

Association study of ghrelin receptor gene polymorphisms in rheumatoid arthritis.

OBJECTIVES: Ghrelin is a newly characterised growth hormone (GH) releasing peptide widely distributed that may play an important role in the regulation of metabolic balance in inflammatory diseases such as rheumatoid arthritis (RA) by decreasing the pro-inflammatory Th1 responses. In this study we investigated the possible contribution of several polymorphisms in the functional Ghrelin receptor to RA susceptibility. METHODS: A screening of 3 single nucleotide polymorphisms (SNPs) was performed in a total of 950 RA patients and 990 healthy controls of Spanish Caucasian origin. Genotyping of all 3 SNPs was performed by real-time polymerase chain reaction technology, using the TaqMan 5'-allele discrimination assay. RESULTS: We observed no statistically significant deviation between RA patients and controls for the GHSR SNPs analysed. In addition, we performed a haplotype analysis that did not reveal an association with RA susceptibility. The stratification analysis for the presence of shared epitope (SE), rheumatoid factor (RF) or antibodies anti cyclic citrullinated peptide (anti-CCP) did not detect significant association of the GHSR polymorphisms with RA. CONCLUSIONS: These findings suggest that the GHSR gene polymorphisms do not appear to play a major role in RA genetic predisposition in our population.

Genetic variation in the nuclear factor kappaB pathway in relation to susceptibility to rheumatoid arthritis.

OBJECTIVE: To examine genetic association between rheumatoid arthritis (RA) and known polymorphisms in core genes of the nuclear factor (NF)kappaB pathway, the major intracellular pathway in RA pathogenesis. METHODS: Discovery and replication sample sets of Spanish patients with RA and controls were studied. A total of 181 single nucleotide polymorphisms (SNPs) uniformly spaced along the genomic sequences of 17 core genes of the NFkappaB pathway (REL, RELA, RELB, NFKB1, NFKB2, NFKBIA, NFKBIB, NFKBIE, IKBKA, IKBKB, IKBKE, IKBKAP, KBRAS1, KBRAS2, MAP3K1, MAP3K14, TAX1BP1) were studied by mass spectrometry analysis complemented with 5'-nuclease fluorescence assays in the discovery set, 458 patients with RA and 657 controls. SNPs showing nominal significant differences were further investigated in the replication set of 1189 patients with RA and 1092 controls. RESULTS: No clear reproducible association was found, although 12 SNPs in IKBKB, IKBKE and REL genes showed significant association in the discovery set. Interestingly, two of the SNPs in the IKBKE gene, weakly associated in the discovery phase, showed a trend to significant association in the replication phase. Pooling both sample sets together, the association with these two SNPs was significant. CONCLUSION: We did not find any major effect among the explored members of the NFkappaB pathway in RA susceptibility. However, it is possible that variation in the IKBKE gene could have a small effect that requires replication in additional studies.

Replication of the tumor necrosis factor receptor-associated factor 1/complement component 5 region as a susceptibility locus for rheumatoid arthritis in a European family-based study.

OBJECTIVE: We recently showed, using a candidate gene approach in a case-control association study, that a 65-kb block encompassing tumor necrosis factor receptor-associated factor 1 (TRAF1) and C5 is strongly associated with rheumatoid arthritis (RA). Compared with case-control association studies, family-based studies have the added advantage of controlling potential differences in population structure and are not likely to be hampered by variation in population allele frequencies, as is seen for many genetic polymorphisms, including the TRAF1/C5 locus. The aim of this study was to confirm this association in populations of European origin by using a family-based approach. METHODS: A total of 1,356 western European white individuals from 452 "trio" families were genotyped for the rs10818488 polymorphism, using the TaqMan allelic discrimination assay. RESULTS: We observed evidence for association, demonstrating departure from Mendel's law, with an overtransmission of the rs10818488 A allele (A = 55%; P = 0.036). By taking into consideration parental phenotypes, we also observed an increased A allele frequency in affected versus unaffected parents (A = 64%; combined P = 0.015). Individuals carrying the A allele had a 1.2-fold increased risk of developing RA (allelic odds ratio 1.24, 95% confidence interval 1.04-1.50). CONCLUSION: Using a family-based study that is robust against population stratification, we provide evidence for the association of the TRAF1/C5 rs10818488 A allele and RA in populations of European descent, further substantiating our previous findings. Future functional studies should yield insight into the biologic relevance of this locus to the pathways involved in RA.

Auto-antibodies, HLA and PTPN22: susceptibility markers for rheumatoid arthritis.

OBJECTIVE: To analyse the relationship between the presence of auto-antibodies [rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP)], HLA-DRB1 alleles and PTPN22 1858 C/T polymorphism and test the value of their combination as susceptibility markers for rheumatoid arthritis (RA). METHODS: Patients with early arthritis were included. At entry in the cohort or during follow-up, 191 patients fulfilled the criteria for RA and 184 individuals suffered from other arthropathies. RF was measured by nephelometry and anti-CCP antibody by enzyme-linked immunosorbent assay. HLA class II alleles were determined by polymerase chain reaction. Samples were genotyped for PTPN22 1858C/T variants using a TaqMan 5'-allele discrimination assay. RESULTS: The presence of shared epitope (SE) alleles was strongly associated with anti-CCP and RF-positive RA [P = 7.05 x 10(-10), odds ratio (OR) 4.57, 95% confidence interval (CI) 2.76-7.57 and P = 1.68 x 10(-6), OR 2.99, 95% CI 1.89-4.74, respectively). The combination of the PTPN22 1858T variant and anti-CCP antibodies gave a high specificity for the disease, and was significantly associated with RA (P = 8.86 x 10(-5), OR 10.05, 95% CI 1.88-53.73). CONCLUSION: The combination of the T variant of the 1858 polymorphism of the PTPN22 gene in combination with the presence of anti-CCP antibodies, preferentially in a SE-positive individual, is associated with the development of RA.

Asporin repeat polymorphism in rheumatoid arthritis.

BACKGROUND: Asporin belongs to a family of proteins associated with the cartilage matrix. OBJECTIVE: To investigate the role of the functional polymorphism consisting of an aspartic acid (D) repeat polymorphism located in the ASPN gene in the susceptibility to and clinical outcome of rheumatoid arthritis. METHODS: A total of 803 Spanish Caucasian patients with rheumatoid arthritis and 904 controls of the same ethnic origin and matched for age and sex were included in the study. The asporin D repeat polymorphism was genotyped using polymerase chain reaction with a fluorescent primer. RESULTS: No significant differences were detected in the distribution of the 10 alleles found in our population on comparing patients with rheumatoid arthritis with control groups. Nevertheless, individuals bearing D14 produced rheumatoid factor more often than the rest (85.7% v 72.1%, p = 0.006, odds ratio (OR) = 2.35, 95% confidence interval 1.21 to 4.50), and the mean (SD) onset age was higher in the group of individuals bearing D13 (50.09 (13.94)) compared with the rest (47.21 (14.31)), although the difference did not reach significance (p = 0.06). CONCLUSION: The results do not support a major role for asporin D repeat polymorphism in the susceptibility to rheumatoid arthritis. Nevertheless, they support the influence of this gene on the outcome of the disease.

Epistatic interaction between FCRL3 and NFkappaB1 genes in Spanish patients with rheumatoid arthritis.

BACKGROUND: A Japanese study has described a strong association between rheumatoid arthritis and several polymorphisms located in the Fc receptor-like 3 (FCRL3) gene, a member of a family of genes related to Fc receptors located on chromosome 1q21-23. OBJECTIVES: To evaluate the association between rheumatoid arthritis and FCLR3 polymorphisms in a large cohort of Caucasian patients with rheumatoid arthritis and healthy controls of Spanish origin. Owing to the described functional link between the FCRL3 polymorphisms and the transcription factor nuclear factor kappaB (NFkappaB), a functional polymorphism located in the NFkappaB1 gene was included. METHODS: 734 patients with rheumatoid arthritis from Madrid and Granada, Spain, were included in the study, along with 736 healthy controls. Polymorphisms in the FCRL3 gene were studied by TaqMan technology. The -94ins/delATTG NFkappaB1 promoter polymorphism was analysed by fragment analysis after polymerase chain reaction with labelled primers. Genotypes were compared using 3x2 contingency tables and chi2 values. RESULTS: No overall differences were found in any of the FCRL3 polymorphisms and in the NFkappaB1 promoter polymorphism when patients were compared with controls. However, when stratified according to NFkappaB1 genotypes, a susceptibility effect of FCRL3 polymorphisms was observed in patients who were heterozygotes for NFkappaB1 (pc = 0.003). CONCLUSIONS: The FCRL3 polymorphisms associated with rheumatoid arthritis in a Japanese population are not associated per se with rheumatoid arthritis in a Spanish population. A genetic interaction was found between NFkappaB1 and FCRL3 in Spanish patients with rheumatoid arthritis. These findings may provide a general rationale for divergent genetic association results in different populations.

PADI4 polymorphisms are not associated with rheumatoid arthritis in the Spanish population.

OBJECTIVES: The presence of anti-citrullinated peptide antibodies is the most specific serological marker known of rheumatoid arthritis (RA). The PADI4 gene, encoding a haematopoietic isoform of the peptidylarginine deiminase citrullinating enzyme, has recently been associated with susceptibility to RA in the Japanese population. A subsequent UK report could not confirm this association, and a later French study also yielded a negative result. Given this discrepancy and the importance of antibodies against citrullinated peptides in the early course of the disease, we performed a replication study. METHODS: Three hundred and fifty-four Spanish RA patients and 498 Spanish controls were recruited from two Madrid hospitals. The padi4_104 and padi4_94 single-nucleotide polymorphisms (SNP) were analysed by TaqMan assays. RESULTS: Similarly to what was described in the British and French population, the less frequent allele of this SNP was not associated with the disease (genotype TT, 16.1% in RA patients vs 14.3% in controls; P = 0.46, odds ratio 1.15, 95% confidence interval 0.78-1.71). A confirmatory negative result was obtained on analysing another SNP in the same gene, padi4_94, in 248 RA patients and 394 controls. CONCLUSIONS: The results of our group and from the British and French studies strongly suggest that polymorphisms of the PADI4 gene do not play a role in susceptibility to RA in European populations.