Associations between Polymorphisms in the IL-1 Gene and the Risk of Rheumatoid Arthritis and Systemic Lupus Erythematosus: Evidence from a Meta-Analysis

<b><i>Background:</i></b> Previous studies on polymorphisms in interleukin-1 (<i>IL-1</i>) and the risk of rheumatoid arthritis (RA)/systemic lupus erythematosus (SLE) yielded inconsistent results. <b><i>Objectives:</i></b> The authors performed this meta-analysis to more robustly evaluate associations between polymorphisms in the <i>IL-1</i> gene and the risk of RA/SLE. <b><i>Methods:</i></b> MEDLINE, Embase, Web of Science, Wanfang, VIP, and CNKI were systematically searched for eligible studies, and 34 relevant studies were finally selected to be eligible for inclusion. <b><i>Results:</i></b> We found that <i>IL-1A</i> +4845G/T polymorphism was significantly associated with the risk of RA in the overall population (dominant comparison: <i>p</i> = 0.02; overdominant comparison: <i>p</i> = 0.05; allele comparison: <i>p</i> = 0.04), whereas <i>IL-1B</i> +3954C/T polymorphism was significantly associated with the risk of RA in the overall population (overdominant comparison: <i>p</i> = 0.03; allele comparison: <i>p</i> = 0.01) and Asians (recessive comparison: <i>p</i> = 0.007; allele comparison: <i>p</i> = 0.002). In addition, we found that <i>IL-1A</i> –889C/T polymorphism was significantly associated with the risk of SLE in Caucasians (allele comparison: <i>p</i> = 0.04), <i>IL-1B</i> –31T/C polymorphism was significantly associated with the risk of SLE in the overall population (recessive comparison: <i>p</i> = 0.04), and <i>IL-1B</i> –511C/T polymorphism was significantly associated with the risk of SLE in Asians (recessive comparison: <i>p</i> = 0.01; allele comparison: <i>p</i> = 0.03). <b><i>Conclusions:</i></b> This meta-analysis suggests that <i>IL-1A</i> +4845G/T and <i>IL-1B</i> +3954C/T polymorphisms may influence the risk of RA, whereas <i>IL-1A</i> –889C/T, <i>IL-1B</i> –31T/C, and <i>IL-1B</i> –511C/T polymorphisms may influence the risk of SLE.