RISK FOR PNEUMONIA AND TLR2 AND TLR4 GENE POLYMORPHISMS: A META-ANALYSIS

Abstract

Pneumonia is one of the most common infections with high mortality rates. The gene polymorphism of Toll-like 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.

Keywords

• tlr2
• tlr4
• polymorphism
• pneumonia
• meta-analysis