Association of interleukin-6 single nucleotide polymorphisms with juvenile idiopathic arthritis

Interleukin-23 receptor gene polymorphisms in Iranian patients with juvenile systemic lupus erythematosus

INTRODUCTION AND OBJECTIVES

Considering the possible roles of interleukin-23 receptor (IL-23R) gene in the pathogenesis of juvenile systemic lupus erythematosus (JSLE), the objective of this study was to elucidate whether polymorphisms of the IL23R are associated with susceptibility to JSLE in an Iranian population.

MATERIALS AND METHODS

A case-control study on 62 patients with JSLE and 78 healthy controls was performed to investigate the associations of four single nucleotide polymorphisms (SNPs) in IL-23R gene, namely, rs7517847, rs10489629, rs11209026, and rs1343151, with susceptibility to JSLE, using real-time polymerase chain reaction Taqman genotyping technique.

RESULTS

Analysis of allele and genotype frequency of four selected SNPs revealed statistically significant positive association between homozygous variant of rs7517847 (TT) (P, 0.02) and T allele at the same position (P, 0.01) with JSLE vulnerability. There was no significant association between other evaluated SNPs and JSLE susceptibility.

CONCLUSION

These findings suggest that particular IL-23R gene variants could affect individual susceptibility to JSLE.

Association between interleukin-1, interleukin-6, and tumor necrosis factor-alpha polymorphisms and juvenile idiopathic arthritis: a meta-analysis

INTRODUCTION

In juvenile idiopathic arthritis (JIA), interleukin (IL)-1, IL-6, and tumor necrosis factor-alpha (TNF-α) are associated with development and progression of JIA. We investigated whether IL-1, IL-6, and TNF-α polymorphisms were associated with susceptibility to JIA.

EVIDENCE ACQUISITION

A meta-analysis was conducted on the associations between IL-1α-899 C/T, IL-1β-511 C/T, IL-6-174 G/C, and TNF-α-308 G/A and -238 G/A polymorphisms, and JIA (PubMed and Embase).

EVIDENCE SYNTHESIS

A total of 27 studies involving 4678 JIA patients and 7634 controls were considered in the meta-analysis. There was no association between the IL-1α-899 C/T, IL-1β-511 C/T, IL-6-174 G/C, and TNF-α-308 G/A and -238 G/A polymorphisms, and JIA in allele contrast or any other genetic models. In subgroup analysis based on subtype, except for the dominant model of TNF-α-238 G/A, systemic JIA was not significantly associated with IL-6 and TNF-α polymorphisms. In Caucasians, the dominant and additive models of IL-1β-511 C/T were significantly associated with JIA (odds ratio [OR] 1.48, 95% confidence interval [CI] 1.09-2.00, P=0.01; OR 1.46, 95% CI 1.05-2.03, P=0.02, respectively).

CONCLUSIONS

This meta-analysis showed no association between IL-1, IL-6, and TNF-α polymorphisms, and JIA, but the TT genotype of IL-1β -511 C/T was associated with higher prevalence of JIA in Caucasians.

Interleukin-6 in juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) is a chronic childhood arthritis. Its pathogenesis is very complicated, with the involvement of not only immune cells but various types of parenchymal cells, and is affected by both genetic and environmental predispositions. The clinical spectrum from inflammation to related conditions is largely mediated by cytokines including interleukin (IL)-6. Fluctuations in IL-6 and its related molecules can modulate the pathogenesis and the clinical presentation positively or negatively. The recent clinical impact of IL-6 blockade on JIA has begun a therapeutic paradigm shift. This review describes the characteristics of JIA, mainly focused on IL-6 with the current therapeutic perspective.

Single nucleotide polymorphism of Methyl-CpG-binding protein 2 gene associates with juvenile idiopathic arthritis

Methyl-CpG-binding protein 2 (MeCP2) is a transcription suppressor or activator, acting through binding to methylated DNA. Numerous investigations have established a role for methylation aberrancies in the pathogenesis of autoimmune disorders. Single nucleotide polymorphisms (SNPs) in MECP2 gene have been implicated with susceptibility to rheumatoid arthritis (RA). Here, the plausible association of MECP2 gene polymorphisms was evaluated with juvenile idiopathic arthritis (JIA) predisposition in Iranian pediatric patients. In this case-control association study, 49 JIA patients and 398 age-, sex-, and ethnicity-matched healthy individuals were included. Genotyping of all samples for MECP2 gene rs1734787, rs1734791, rs1734792, and rs17435 polymorphisms was conducted by real-time allelic discrimination PCR technique. Except the AT genotype of rs17435 SNP, none of the alleles and genotypes of other positions were distributed significantly between JIA cases and controls. AT genotype was less frequent in JIA cases and was found to be protective genotype of JIA proneness (OR = 0.42; CI, 0.19-0.90; P = 0.028). Among the haplotypes, CCAA and TTTT were detected to have significant difference between cases and controls (OR = 1.74; CI, 1.01-2.98; P = 0.042 and OR = 1.82; CI, 1.05-3.13; P = 0.028). All positions were in linkage disequilibrium with each other according to D'. MECP2 gene rs17435 polymorphism was associated with JIA predisposition. Considering the involvement of genetic polymorphisms of MECP2 gene in susceptibility to adult-onset RA, this gene might basically play a role in the initiation of arthritis during early stages of life.