The risk of atopic dermatitis may be affected by IL-1B +3954 C/T and IL-18 -137G/C polymorphisms: evidence from a meta-analysis

Introduction
Whether Th1-related cytokine polymorphisms influence the risk of atopic dermatitis (AD) remain inconclusive

Aim
The authors performed a meta-analysis to robustly explore relationships between Th1-related cytokine polymorphisms and the risk of AD by merging the results of eligible publications.

Material and methods
The authors strictly adhere to the PRISMA guidelines in study design and implementation. A thorough literature search in Medline, Embase, Wanfang, VIP and CNKI was performed by the authors to identify eligible publications. Relationships between TNF-/IL-1/IL-6/IL-18 polymorphisms and the risk of AD were estimated with odds ratio and its 95% confidence interval. The statistically significant p value was set at 0.05. The quality of eligible publications was assessed by the Newcastle-Ottawa scale (NOS).

Results
In total twenty-one publications with a NOS score of 7-8 were selected for merged quantitative analyses. We have noticed that genotypic frequencies of IL-1B +3954 C/T and IL-18 -137G/C polymorphisms among cases with AD and population-based controls differed significantly. Moreover, we have found that genotypic frequency of IL-1B +3954 C/T polymorphism among cases with AD and population-based controls of Caucasian origin differed significantly, and genotypic frequency of IL-18 -137G/C polymorphism among cases with AD and population-based controls of both Caucasian and Asian origins also differed significantly. However, we did not observe such genotypic distribution differences for TNF- -238 G/A, TNF- -308 G/A, IL-1A -889 C/T, IL-1B 511 C/T and IL6 -174 G/C polymorphisms.

Conclusions
The present meta-analysis shows that IL-1B +3954 C/T and IL-18 -137G/C polymorphisms may affect the risk of AD.