Association Between Il-4, Il-6, Il-18 Polymorphisms And Atopic Dermatitis Risk: A Meta-Analysis

Background: Atopic dermatitis (AD) is one of common chronic and relapsing inflammatory diseases with a strong genetic predisposition. Abnormal cytokine production might have an effect on the biology of AD development. Objective: The aim of this study was to identify whether polymorphisms of interleukin (IL)-4, IL-6 and IL-18 were associated with AD susceptibility. Methods: Relevant investigations between 2000 and 2015 were searched from online databases. The value of odds ratio (OR) and its 95% confidence interval (CI) were calculated to assess these relationship. Results: A total of 14 papers were finally selected for this study, including 1550 controls and 1021 AD patients. There were seven studies for IL-18, five for IL-4, and four for IL-6 polymorphisms, respectively. Meta-analysis revealed an obvious relationship between IL-18 -137G/C polymorphism and AD under the homozygous model (CC vs. GG: OR= 0.27, 95% CI= 0.13-0.54, P=0.0002) and recessive model (CC vs. GC+GG: OR=0.31, 95% CI= 0.16-0.61, P= 0.0007) in a fixed-effect model. The GA genotype of IL-6 nt565G/A polymorphism in heterozygous model was correlated with increased the risk of AD (GA vs. GG: OR= 0.68, 95% CI= 0.48-0.96, P= 0.03) as well. However, this significant association was not found in other genotypes (all P>0.05). Conclusions: These results indicated that CC genotype of IL-18 -137G/C polymorphism and GA genotype of IL-6 nt565G/A polymorphism were risk factors for AD. Future studies with large population were still needed to further explore these corrections.