Investigation of an interleukin-6 receptor gene polymorphism (rs2228145) as a predictor of cardiovascular mortality in inflammatory polyarthritis: results from the Norfolk Arthritis Register

Relationship Between Interleukin-6 -174G/C Genetic Variant and Efficacy of Methotrexate Treatment in Psoriatic Arthritis Patients

Introduction

The purpose of the study was to investigate whether single-nucleotide polymorphisms (SNPs) IL-6 −174 G/C and IL-6R Asp358Ala are associated with susceptibility to psoriatic arthritis (PsA) or affect response to treatment with methotrexate (MTX).

Patients and Methods

Seventy-four patients diagnosed with PsA and qualified for MTX treatment were enrolled to the study. The control group consisted of 120 healthy individuals. Polymorphisms IL-6 −174 G/C and IL-6R Asp358Ala were genotyped using a polymerase chain reaction (PCR) amplification employing LightSNiP assays.

Results

A significant association between the IL-6 −174 CC genotype and an improved clinical outcome of MTX therapy was observed. A good response was more frequently observed among PsA patients bearing the IL-6 −174 CC genotype than patients with the GC or GG genotypes (P = 0.007). On the other hand, patients carrying the IL-6 −174 GC genotype less frequently responded to MTX treatment as compared to patients with other genotypes (P = 0.006). With respect to the IL-6R Asp358Ala SNP, there were no significant differences in genotype and allelic frequencies in relation to clinical outcome of MTX treatment. No association was found between the IL-6 −174 G/C or IL-6R Asp358Ala SNPs and PsA susceptibility.

Conclusion

Results from this study provide evidence that the IL-6 −174 G/C polymorphism might influence efficacy of MTX treatment.

Sudden cardiac death in patients with rheumatoid arthritis

An increased cardiovascular morbidity and mortality, including the risk of sudden cardiac death (SCD), has been shown in patients with rheumatoid arthritis (RA). Abnormalities in autonomic markers such as heart rate variability and ventricular repolarization parameters, such as QTc interval and QT dispersion, have been associated with sudden death in patients with RA. The interplay between these parameters and inflammation that is known to exist with RA is of growing interest. In this article, we review the prevalence and predictors of SCD in patients with RA and describe the potential underlying mechanisms, which may contribute to this. We also review the impact of biologic agents on arrhythmic risk as well as cardiovascular morbidity and mortality.

The rs2228145 polymorphism in the interleukin-6 receptor and its association with long-term prognosis after myocardial infarction in a pilot study

INTRODUCTION

Interleukin-6 (IL-6) is a cytokine with a complex function that is described as both pro- and anti-inflammatory. One factor that influences its function is the rs2228145 A/C single nucleotide polymorphism (SNP) of the IL-6 receptor (IL6R) gene. C allele carriers have a decreased inflammatory response and decreased prevalence of ischemic heart disease. The aim of the study was to investigate the association of the rs2228145 SNP of the IL6R gene with long-term total mortality in patients with ST-elevation myocardial infarction (STEMI) treated invasively.

MATERIAL AND METHODS

We analyzed the data of consecutive patients with ST elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (PCI). Genotyping was performed with the TaqMan method. The analyzed end-point was total long-term mortality (median: 2875 days).

RESULTS

The registry comprised 553 patients (mean age: 62.4 ±11.9 years; 25.6% females, n = 142; TIMI 3 obtained in 91.7% of patients, n = 507). No significant differences in baseline characteristics were found between the genotypes. During long-term follow-up 171 (30.9%) patients died. There was non-significantly higher mortality in the rs2228145 AA homozygotes compared to C allele carriers (OR = 1.34, 95% CI: 0.93-1.93, p = 0.1).

CONCLUSIONS

The rs2228145 polymorphism of IL6R was not significantly associated with long-term mortality after STEMI. However, AA homozygotes (high-risk genotype for ischemic heart disease) showed a trend towards adverse outcome compared to C allele carriers. The observed trend is promising, but it requires independent replication studies.

Association of HLA-DRB1 haplotypes with rheumatoid arthritis severity, mortality, and treatment response

IMPORTANCE

Advances have been made in identifying genetic susceptibility loci for autoimmune diseases, but evidence is needed regarding their association with prognosis and treatment response.

OBJECTIVE

To assess whether specific HLA-DRB1 haplotypes associated with rheumatoid arthritis (RA) susceptibility are also associated with radiological severity, mortality, and response to tumor necrosis factor (TNF) inhibitor drugs.

DESIGN, SETTING, AND PARTICIPANTS

The Norfolk Arthritis Register (NOAR; 1691 patients and 2811 radiographs; recruitment: 1989-2008; 2008 as final follow-up) was used as a discovery cohort and the Early Rheumatoid Arthritis Study (421 patients and 3758 radiographs; recruitment: 1986-1999; 2005 as final follow-up) as an independent replication cohort for studies of radiographic outcome. Mortality studies were performed in the NOAR cohort (2432 patients; recruitment: 1990-2007; 2011 as final follow-up) and studies of treatment response in the Biologics in Rheumatoid Arthritis Genetics and Genomics Study Syndicate cohort (1846 patients enrolled at initiation of TNF inhibitor; recruitment: 2006-2010; 2011 as final follow-up). Longitudinal statistical modeling was performed to integrate multiple radiograph records per patient over time. All patients were from the United Kingdom and had self-reported white ancestry.

EXPOSURES

Sixteen HLA-DRB1 haplotypes defined by amino acids at positions 11, 71, and 74.

MAIN OUTCOMES AND MEASURES

Radiological outcome using the Larsen score (range: 0 [none] to 200 [severe joint damage]) and erosions of the hands and feet on radiographs, all-cause mortality, and treatment response measured by change in Disease Activity Score based on 28 joint counts and European League Against Rheumatism (EULAR) response.

RESULTS

Patients with RA and valine at position 11 of HLA-DRB1 had the strongest association with radiological damage (OR, 1.75 [95% CI, 1.51-2.05], P = 4.6E-13). By year 5, the percentages of patients with erosions of the hands and feet were 48% of noncarriers (150/314) of valine at position 11, 61% of heterozygote carriers (130/213), and 74% of homozygote carriers (43/58). Valine at position 11 also was associated with higher all-cause mortality in patients with inflammatory polyarthritis (hazard ratio, 1.16 [95% CI, 1.03-1.31], P = .01) (noncarriers: 319 deaths in 1398 patients over 17,196 person-years, mortality rate of 1.9% per year; carriers: 324 deaths in 1116 patients in 13,208 person-years, mortality rate of 2.5% per year) and with better EULAR response to TNF inhibitor therapy (OR, 1.14 [95% CI, 1.01-1.30], P = .04) (noncarriers: 78% [439/561 patients] with moderate or good EULAR response; heterozygote carriers: 81% [698/866]; and homozygote carriers: 86% [277/322]). The risk hierarchy defined by HLA-DRB1 haplotypes was correlated between disease susceptibility, severity, and mortality, but inversely correlated with TNF inhibitor treatment response.

CONCLUSIONS AND RELEVANCE

Among patients with RA, the HLA-DRB1 locus, which is associated with disease susceptibility, was also associated with radiological severity, mortality, and treatment response. Replication of these findings in other cohorts is needed as a next step in evaluating the role of HLA-DRB1 haplotype analysis for management of RA.