An association between single nucleotide polymorphisms within TLR and TREM-1 genes and infective endocarditis

•Immune response gene polymorphisms may be associated with risk of various diseases.•TLR and TREM-1 gene polymorphisms may be associated with IE risk.•TLR6 gene rs3775073 polymorphism may be associated with 2-fold decrease of IE risk.•Other investigated SNPs within TLR and TREM-1 genes are not associated with IE.•There is no age/gender dependence on association of TLR and TREM-1 SNPs with IE.

Infective endocarditis (IE) is an inflammatory condition of the lining of the heart chambers and valves, which is generally caused by bacteria. Toll-like receptors (TLRs) and Triggering receptor expressed on myeloid cells (TREMs) are key effectors of the innate system that play a significant role in the recognition of infectious agents, particularly, bacteria. We hypothesised that inherited variation in TLR and TREM-1 genes may affect individual susceptibility to IE. The distribution of genotypes and alleles of the TLR1 (rs5743551, rs5743611), TLR2 (rs3804099, rs5743708), TLR4 (rs4986790, rs4986791), TLR6 (rs3775073, rs5743810), and TREM-1 (rs1817537, rs3804277, rs6910730, rs7768162, rs2234246, rs4711668, rs9471535, rs2234237) gene polymorphisms was investigated in 110 Caucasian (Russian) subjects with IE and 300 age-, sex-, and ethnicity-matched healthy blood donors. Odds ratios with 95% confidence intervals were calculated. We found that C/C genotype of the rs3775073 polymorphism within TLR6 gene was associated with a decreased risk of IE (OR = 0.51, 95% CI = 0.26-0.97, P = 0.032) according to the recessive model; however, we observed no association between the other investigated SNPs within TLR and TREM-1 genes and IE. Further in-depth investigations in this field are necessary to shed the light on the impact of inherited variation within innate immune response genes on the development of IE.