Associations between Certain Polymorphisms in Proinflammatory Cytokines and Predisposition of Alzheimer’s Disease: A Meta-Analysis

Abstract

<b><i>Background:</i></b> Functional gene polymorphisms of proinflammatory cytokines such as tumor necrosis factor-α (<i>TNF-α</i>), interleukin-6 (<i>IL-6</i>), interleukin-8 (<i>IL-8</i>), and interleukin-18 (<i>IL-18</i>) may contribute to the onset and development of Alzheimer’s disease (AD), but the relationships between these polymorphisms and predisposition of AD remain controversial. <b><i>Objectives:</i></b> This meta-analysis was conducted to more robustly assess relationships between <i>TNF-α/IL-6/IL-8/IL-18</i> polymorphisms and predisposition of AD by pooling the findings of relevant studies. <b><i>Methods:</i></b> A comprehensive literature searching was performed in PubMed, Embase, Web of Science, Wanfang, and CNKI databases, and 63 studies were found to be eligible for quantitative analyses. <b><i>Results:</i></b> The pooled meta-analysis results showed that genotypic frequencies of <i>TNF-α</i> rs1800629, <i>IL-6</i> rs1800795, <i>IL-8</i> rs4073, and <i>IL-18</i> rs187238 polymorphisms among AD cases and controls of Asian ethnicity differed significantly. But, we did not observe such genotypic frequencies differences in Caucasians. <b><i>Conclusions:</i></b> This meta-analysis suggests that <i>TNF-α</i> rs1800629, <i>IL-6</i> rs1800795, <i>IL-8</i> rs4073, and <i>IL-18</i> rs187238 polymorphisms may affect predisposition of AD in Asians, but not in Caucasians.