Risk for pneumonia and TLR2 and TLR4 gene polymorphisms: A meta-analysis

Pneumonia is one of the most common infections with high mortality rates. The gene polymorphism of Tolllike receptors that belong to the first line of defense of the immune system can make a considerable contribution to individual variability due to the risk of pneumonia. Today this issue has not been adequately explored and the data available in the literature are conflicting. Objective: to carry out a meta-analysis of the association between Toll-like receptor gene polymorphic variants and the risk of pneumonias and its coinfections. Methods. A meta-analysis was carried out to detect a possible association of the risk of pneumonia and coinfections with single nucleotide polymorphisms (SNP) in the TLR2 (rs5743708 (2258 G>A; Arg753Gln) and TLR4 (rs4986790 (896A>G; Asp299Gly) genes. The investigation enrolled 2312 (682 patients/1630 control individuals) and 3075 (910/2165) Caucasians for each SNP, respectively. As the rate of minor alleles of both polymorphic variants was less than 5%; the analysis was made only for a dominant genetic model. Results. Analysis of the study group showed that the A allele of TLR2 rs5743708 was associated with the risk of pneumonia (OR = 1.90; 95% CI: 1.02-3.54; P=0.042) while TLR4 rs4986790 was not associated with pneumonia. Analysis of subgroups (children/adults and community-acquired/nosocomial pneumonia) revealed no significant effects. Conclusion. The A allele of TLR2 rs5743708 may be a risk factor for susceptibility to pneumonia. These results have promises for their clinical application; however, due to the high heterogeneity and insufficient sizes of samples, these results need to be confirmed by further investigations. © 2015, V.A. Negovsky Research Institute of General Reanimatology. All rights reserved