Interleukin-1 promoter region polymorphism role in rheumatoid arthritis: a meta-analysis of IL-1B-511A/G variant reveals association with rheumatoid arthritis

Objectives. IL-1 has a central role mediating inflammation and joint destruction in RA. Single nucleotide polymorphisms (SNPs) and haplotype structure in the promoter region can modulate IL-1 function. This study examined the effects of four common promoter SNPs in the IL-1 region on susceptibility and clinical characteristics of RA in British Caucasian patients and assessed the risk of RA by meta-analysis of published studies. Methods. Using PCR-based methods, 756 RA patients and 625 healthy controls (HCs) were genotyped for IL-1A (889 C/A, rs17561), IL-1B (511 A/G, rs16944), IL-1B (1464 C/G, rs1143623) and IL-1B (3737 G/A, rs4848306) SNPs. Further meta-analysis was performed for IL-1B (511 A/G) incorporating 3712 RA patients and 2331 HC from six association studies. Results. The IL-1B (1464 C/G) G allele was found to be less common in the RA group [P 0.01; odds ratio (OR) 1.24; 95 CI 1.04, 1.48]. There was no association between IL-1 SNPs and the presence of HLA-DRB1 shared epitope, RF or clinical characteristics. Meta-analysis revealed statistically significant association between IL-1B (511 A/G) and RA (P 0.02; pooled OR 1.13; 95 CI 1.02, 1.26). Conclusions. There may be a protective effect in RA from the IL-1B (1464 C/G) G variant. No direct association between the polymorphisms studied and clinical severity characteristics were observed. Further meta-analysis revealed IL-1B (511 A/G) to be associated with increased susceptibility to RA.