Dora Pascual-Salcedo

Influence of immunogenicity on the efficacy of long-term treatment with infliximab in rheumatoid arthritis

OBJECTIVE To analyse the clinical relevance of the production of anti-infliximab antibodies (anti-infliximab Abs) in patients with RA undergoing infliximab treatment over a prolonged period of time. METHODS Clinical characteristics, serum trough infliximab and antibody levels were evaluated in 85 RA patients treated with infliximab for a median of 4.42 (interval 0.4-10.2) years. DAS in 28 joints (DAS-28), EULAR response criteria and survival of treatment were assessed at 3 time points (6 months, 12 months and >4 years). RESULTS Antibodies against infliximab were detected in 28 (32.9%) patients and were present in all EULAR non-responder patients. Antibody levels were higher in EULAR non-responders throughout the study period (P = 0.05 at 6 months, P = 0.02 at 1 year, P = 0.003 at >4 years) compared with EULAR (good and moderate) responders. Nine (10.5%) patients, all of them with high-serum anti-infliximab Ab levels, developed infusion-related reactions. Patients with anti-infliximab Abs more often required increased infliximab doses (51.7%) (P = 0.032) and median survival time on treatment was shorter (4.15 vs 8.89 years) (P = 0.0006). MTX co-therapy was not associated with lower proportion of anti-infliximab Ab-positive patients, but those receiving both infliximab and MTX had lower levels of anti-infliximab Abs (P = 0.073) and longer survival (P = 0.015) on treatment. CONCLUSION The formation of anti-infliximab Abs during treatment with infliximab is associated with a loss of clinical response, the appearance of infusion reactions and discontinuation of treatment.

Protection against anti–citrullinated protein antibody–positive rheumatoid arthritis is predominantly associated with HLA–DRB1*1301: A meta-analysis of HLA–DRB1 associations with anti–citrullinated protein antibody–positive and anti–citrullinated protein antibody–negative rheumatoid arthritis in four European populations

OBJECTIVE The protective effect of HLA-DRB1 alleles on the development of rheumatoid arthritis (RA) is poorly understood. The aim of this study was to perform a meta-analysis of 4 European populations to investigate which HLA-DRB1 alleles are associated with protection in anti-citrullinated protein antibody (ACPA)-positive RA and ACPA-negative RA. METHODS Data for >2,800 patients and >3,000 control subjects for whom information on HLA-DRB1 typing and ACPA status was available were collected from 4 European countries: Norway, Sweden, The Netherlands, and Spain. The odds ratios (ORs) and 95% confidence intervals (95% CIs) associated with the different HLA-DRB1 alleles were analyzed in a combined meta-analysis focused on protective alleles and classifications. The analysis of ACPA-positive RA was stratified for the shared epitope (SE) alleles, to correct for skewing due to this association. RESULTS In ACPA-positive RA, the only alleles that conveyed protection after stratification for SE were HLA-DRB1*13 alleles (OR 0.54 [95% CI 0.38-0.77]). The protective effect of the allele classifications based on the DERAA and D70 sequences was no longer present after exclusion of DRB1*13 (for D70, OR 0.97 [95% CI 0.75-1.25]), indicating that DRB1*13, rather than the DERAA or D70 sequence as such, is associated with protection. Among the DRB1*13 alleles, only DRB1*1301 was associated with protection (OR 0.24 [95% CI 0.09-0.59]). Protection appeared to follow a north-to-south gradient, with the strongest association in northern European countries. In ACPA-negative RA, there were no robust associations with HLA-DRB1 alleles. CONCLUSION Our data do not support any of the classifications of protective alleles and indicate that protection against ACPA-positive RA is predominantly associated with HLA-DRB1*1301.

Linkage proof for PTPN22, a rheumatoid arthritis susceptibility gene and a human autoimmunity gene

The tyrosine phosphatase PTPN22 allele 1858T has been associated with rheumatoid arthritis (RA) and other autoimmune diseases. RA is the most frequent of those multifactorial diseases. The RA association was usually restricted to serum rheumatoid factor positive disease (RF+). No interaction was shown with HLA-DRB1, the first RA gene. Many case-control studies replicated the RA association, showing an allele frequency increase of ≈5% on average and large variations of population allele frequencies (2.1–15.5%). In multifactorial diseases, the final proof for a new susceptibility allele is provided by departure from Mendels law (50% transmission from heterozygous parents). For PTPN22–1858T allele, convincing linkage proof was available only for type 1 diabetes. We aimed at providing this proof for RA. We analyzed 1,395 West European Caucasian individuals from 465 “trio” families. We replicated evidence for linkage, demonstrating departure from Mendels law in this subset of early RA onset patients. We estimated the overtransmission of the 1858T allele in RF+ families: T = 63%, P < 0.0007. The 1858T allele frequency increased from 11.0% in controls to 17.4% in RF+ RA for the French Caucasian population and the susceptibility genotype (1858T/T or T/C) from 20.2% to 31.6% [odds ratio (OR) = 1.8 (1.2–2.8)]. In conclusion, we provided the linkage proof for the PTPN22–1858T allele and RF+ RA. With diabetes and RA, PTPN22 is therefore a “linkage-proven” autoimmunity gene. PTPN22 accounting for ≈1% of the RA familial aggregation, many new genes could be expected that are as many leads to definitive therapy for autoimmune diseases.

Genome‐wide association study of rheumatoid arthritis in the Spanish population: KLF12 as a risk locus for rheumatoid arthritis susceptibility

OBJECTIVE To identify new genes associated with susceptibility to rheumatoid arthritis (RA), using a 2-stage genome-wide association study. METHODS Following a liability-based study design, we analyzed 317,503 single-nucleotide polymorphisms (SNPs) in 400 patients with RA and 400 control subjects. We selected a group of candidate SNPs for replication in an independent group of 410 patients with RA and 394 control subjects. Using data from the 3 previous genome-wide association studies in RA, we also looked for genomic regions showing evidence of common association signals. Finally, we analyzed the presence of genome-wide epistasis using the binary test implemented in the PLINK program. RESULTS We identified several genomic regions showing evidence of genome-wide association (P < 1 x 10(-5)). In the replication analysis, we identified KLF12 SNP rs1324913 as the most strongly associated SNP (P = 0.01). In our study, we observed that this SNP showed higher significance than PTPN22 SNP rs2476601, in both the genome-wide association studies and the replication analyses. Furthermore, the integration of our data with those from previous genome-wide association studies showed that KLF12 and PTPRT are the unique loci that are commonly associated in 3 different studies (P = 0.004 and P = 0.002 for KLF12 in the Wellcome Trust Case Control Consortium study and the Brigham and Womens Rheumatoid Arthritis Sequential Study genome-wide association study, respectively). The genome-wide epistasis analysis identified several SNP pairs close to significance after multiple test correction. CONCLUSION The present genome-wide association study identified KLF12 as a new susceptibility gene for RA. The joint analysis of our results and those from previous genome-wide association studies showed genomic regions with a higher probability of being genuine susceptibility loci for RA.

Primary association of tumor necrosis factor–region genetic markers with susceptibility to rheumatoid arthritis

OBJECTIVE To determine whether tumor necrosis factor (TNF) polymorphisms are associated with susceptibility to rheumatoid arthritis (RA) independently of the HLA-DR shared epitope. METHODS Fifty-two Spanish families with one or more affected members were typed for HLA-DRB1, TNF promoter polymorphisms, and TNFa and TNFb microsatellites. We performed an association analysis comparing transmitted versus not transmitted haplotypes, with or without shared epitope, to determine whether there is an independent effect of TNF genetic markers on RA susceptibility. RESULTS TNFa6,b5 was significantly associated with susceptibility to RA. The haplotypes containing these markers were preferentially transmitted to the affected offspring, even if these haplotypes lacked the HLA-DR shared epitope. TNF promoter polymorphisms were not associated with susceptibility to RA. CONCLUSION The data suggest that TNFa/b is an independent marker of RA susceptibility, pointing to a genetic role of the TNF region in the pathogenesis of RA.

NFKB1-94ATTG ins/del polymorphism (rs28362491) is associated with cardiovascular disease in patients with rheumatoid arthritis

INTRODUCTION Rheumatoid arthritis (RA) is an inflammatory disease associated with increased cardiovascular (CV) mortality. A recent study has disclosed association between NFKB1-94ATTG ins/del polymorphism and higher risk of coronary heart disease in healthy Caucasians. Because of that, we assessed the influence of this polymorphism in the risk of CV disease in RA patients. MATERIAL AND METHODS 1437 Spanish patients with RA were genotyped for the NFKB1-94ATTG ins/del polymorphism. Two hundred and seventy-one of them (18.8%) had experienced CV events. RESULTS After adjusting for sex, age at RA diagnosis and traditional CV risk factors RA patients carrying the NFKB1 del/del genotype had higher risk of CV events than those with ins/ins genotype (Hazard ratio [HR] = 1.76, 95% CI: 1.05-2.97, p = 0.03), while heterozygous patients had an intermediate (but non-significant) risk (HR = 1.31, 95% CI: 0.90-1.92, p = 0.16). CONCLUSION Our results suggest that NFKB1-94ATTG ins/del polymorphism is associated with CV disease in patients with RA.

Genetic polymorphisms in Spanish rheumatoid arthritis patients: an association and linkage study

HLA polymorphism accounts only for approximately one-third of the genetic predisposition to rheumatoid arthritis (RA). To investigate the role of other loci in the susceptibility to RA, we have performed an analysis of several polymorphisms in genes of immune-related function: IL-10 −1082, −819, −592 promoter single nucleotide polymorphisms (SNPs), IL-10G and IL-10R microsatellites, IL-6 −622 promoter SNP, FcγRIIIA Val/Phe-158 polymorphism, IL-1 receptor antagonist VNTR, and the IKBL+738 T/C mutation. The analysis has been performed on a case–control study and also on RA trios. IL-10G12 was found to be associated with RA in the case–control study (18% in RA patients vs 9% in controls: P=0.001; pc<0.05). This allele was also more often transmitted than not transmitted (10 vs 5). No other allele in the present study is found to be associated to RA. Our data suggest that most of the loci studied play no major role in the susceptibility to RA, the IL-10 gene being the sole exception.

Primary association of a MICA allele with protection against rheumatoid arthritis

OBJECTIVE To determine whether major histocompatibility complex class I chain-related gene A (MICA) polymorphisms are associated with susceptibility to rheumatoid arthritis (RA) independently of the HLA-DRB1 shared epitope (SE). METHODS Fifty-four Spanish families with an affected son or daughter and 211 consecutive RA patients were genotyped for HLA-DRB1, tumor necrosis factor a/b microsatellite alleles, and MICA transmembrane polymorphism. We performed a case-control comparison with the consecutive patients and an independent transmission disequilibrium test with the families. RESULTS The frequency of the MICA 6.0 allele was significantly reduced, compared with controls, in the group of SE+ patients (odds ratio 0.39, P = 0.0005). Additionally, the haplotypes containing this allele were preferentially not transmitted to the affected offspring (9 transmitted of 33; P = 0.007), independent of the presence or absence of an SE either in the same haplotype or in the other haplotype in the progenitor. CONCLUSION These data suggest that the MICA 6.0 allele is an independent marker of protection against RA in the SE+ group of 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.

Characterization of VLA-4-dependent myeloma cell adhesion to fibronectin and VCAM-1.

The integrin VLA‐4 mediates attachment of myeloma cells to multiple myeloma (MM) bone marrow stroma. The alternatively‐spliced CS‐1 region of fibronectin (FN) and VCAM‐1 are main ligands for VLA‐4 and are both expressed on MM stroma. The H1 region is present in all FN isoforms and represents an additional binding site for VLA‐4. We employed FN fragments FN‐H89 and FN‐H0, that contain either the CS‐1 and H1, or only the H1 sites, respectively, as well as soluble VCAM‐1 (sVCAM‐1), to characterize VLA‐4‐mediated adhesion pathways used by myeloma cells to attach to MM stroma. CD38highCD45RA− cells from MM bone marrow, and the myeloma‐derived cell lines NCI‐H929, IM‐9 and RPMI 8226, specifically adhered, by different degrees, to FN‐H89, FN‐H0 and sVCAM‐1, and their VLA‐4‐dependent adhesion was substantially up‐regulated by the anti‐β1 antibody TS2/16, which increases the affinity of VLA‐β1 integrins. Furthermore, VLA‐4 function on NCI‐H929 cells was enhanced by TS2/16 during adhesion to MM stroma. The α4β7 integrin mediated a small portion of myeloma cell line adhesion to FN‐H89, mainly upon integrin activation with Mn2+. These results indicate that myeloma cells use VLA‐4 to interact with CS‐1/FN, H1/FN and VCAM‐1 on MM stroma, and that its function can be potentially up‐regulated, enabling higher degrees of cell adhesion to these VLA‐4 ligands, which might influence myeloma cell localization in the bone marrow.