Association between IL-4 and IL-4R Polymorphisms and Periodontitis: A Meta-Analysis.

Background. Previous studies have revealed that gene polymorphisms of inflammatory factors may influence the development or progression of periodontitis, a main cause of tooth loss in adults; however, due to limitations of individual studies, inconsistent findings were reported. Objective. To meta-analytically investigate the relationship between periodontitis and the Interleukin-4 (IL-4) and Interleukin-4 receptor (IL-4R) gene polymorphisms. Methods. Databases were searched for relevant case-control studies. After study selection based on the predefined selection criteria, methodological quality assessment and data extraction were conducted independently by two reviewers, before subsequent statistical analyses. Results. 37 studies involving 4,385 patients and 5,168 controls were included. All the studied IL-4 polymorphisms were not significantly associated with periodontitis, except the -33C/T (CT versus CC: OR = 0.50, 95% CI = 0.28-0.88) associated with reduced AgP susceptibility. Positive association was found between IL-4R Q551 polymorphism and periodontitis susceptibility in three genetic models (R versus Q: OR = 1.59, 95% CI = 1.14-2.22; QR versus QQ: OR = 1.84, 95% CI = 1.21-2.80; RR + QR versus QQ: OR = 1.82, 95% CI = 1.22-2.72). Conclusions. A positive association exists between the IL-4R Q551R polymorphism and occurrence of CP. The IL-4 -33 CT genotype is negatively associated with the occurrence of AgP.