Interleukin-6-174G/C Polymorphism Contributes to Periodontitis Susceptibility: An Updated Meta-Analysis of 21 Case-Control Studies

Abstract

Introduction. Chronic Periodontitis (CP) is suggested to be related to gene variations. Present study aims to quantitatively estimate the association between interleukin-6- (IL-6-) 174G/C polymorphism and CP susceptibility. Materials and Methods. Pubmed, Embase, and Web of Science were searched up to May 2016. The meta-analyses were performed using STATA 12.0. Results. 21 studies were yielded. Significant associations were found under heterozygote comparison and dominant model in studies fulfilling HWE (GC versus GG: OR = 0.690, 95% CI = 0.560–0.849, P = 0.000; CC + GC versus GG: OR = 0.690, 95% CI = 0.568–0.838, P < 0.001); significant associations were found under heterozygote comparison and dominant model in Caucasian studies fulfilling HWE (GC versus GG: OR = 0.752, 95% CI = 0.577–0.980, P = 0.035; CC + GC versus GG: OR = 0.737, 95% CI = 0.576–0.944, P = 0.016); significant associations were found under allele comparison, heterozygote comparison, and dominant model in Brazilian population (C versus G: OR = 0.648, 95% CI = 0.497–0.845, P = 0.001; GC versus GG: OR = 0.621, 95% CI = 0.441–0.876, P = 0.007; CC + GC versus GG: OR = 0.649, 95% CI = 0.470–0.896, P = 0.009). Conclusion. IL-6 174 polymorphism is associated with CP susceptibility. In Brazilian and Caucasian population, IL-6 174 GG genotype plays as a risk factor to CP.

Contribution of Interleukin-10-592 (-590, -597) C>A Polymorphisms to Periodontitis Susceptibility: An Updated Meta-Analysis Based on 18 Case-Control Studies

“…It was demonstrated that the associations between genetic polymorphisms and certain diseases varied with different geographical regions and ethnic groups [ 6 ]. Therefore, we also investigated the contributions of ethnicity to the risk of disease.…”

“…As we know, interstudy heterogeneity and publication bias are main limitations associated with meta-analyses. Heterogeneity can be caused by many factors such as race, sample sizes, smoking habits, and deviations of allele distributions from the HWE [ 6 ]. There was obvious heterogeneity in the overall analysis involving CP individuals.…”

“…Another factor that we considered in our analysis was publication bias. Publication bias stems from the fact that positive results are much more readily published by journals, whereas negative results tend to be poorly received by journals and are collectively known as “grey literature” [ 6 , 14 , 15 ]. In the present study, we used Egger's test to probe the occurrence of publication bias, and the results indicated apparent publication bias in HWE fulfillment, as well as in the Caucasian population subgroup analysis in the CP versus controls allele comparison, which may have distorted our present results.…”

“…The final scores were calculated ranging from 0 to 9. Studies with scores of 0–3, 4–6, and 7–9 points were considered of low, moderate, and high quality, respectively [ 6 , 35 ].…”

Peer Review #1 of "IL-6 and TNF-α salivary levels according to the periodontal status in Portuguese pregnant women (v0.1)"

“…Thus, qualitative changes in the levels of these biomarkers could have diagnostic and therapeutic significance. Interleukin 6 (IL-6) is a pro-inflammatory cytokine associated with the severity of periodontitis contributing to bone resorption (Moreira et al, 2007;Graves, 2008;Jaedicke, Preshaw & Taylor, 2016;Zhu et al, 2016). TNF-α is a proinflammatory cytokine that has an effect in the activation of inflammatory leukocytes, modification of vascular permeability and induction of bone resorption (Assuma et al, 1998;Varghese et al, 2015) and is a main inducer of IL-6 (Katz, Nadiv & Beer, 2001).…”