TLR4 -2604G>A variant confers differential DNA binding capacity to transcription factors of the GATA family and alters gene expression in peripheral blood of atherosclerotic patients.

Aim: Toll-like receptor-4 (TLR4) is a primary receptor of the innate immune reaction and compelling evidence demonstrate its envelopment in the pathogenesis of atherosclerosis. TLR4 is constitutively expressed on monocytes and endothelial cells, and it has been found to be highly expressed in atherosclerotic plaques, and in peripheral blood of patients after ischemic stroke. Polymorphisms in the promoter region of this gene may represent genetic risk factors involved in the predisposition to atherosclerotic disease. In this study we investigated the effect on TLR4 gene expression of three polymorphisms located in the 5’ upstream region of the gene in peripheral blood of atherosclerotic patients. Methods: Polymorphisms -1607T>C (rs10759932) and -2026A>G (rs1927914) were genotyped by PCR-RFLP, and gene expression analysis was performed by Real Time PCR using Sybr Green in 62 atherosclerotic patients. Results: RNA from patients carrying the allele -2604A in homozygosis showed a lower expression of the gene when compared to patients carrying the counterparts GG + GA (P<0.02). EMSA assays demonstrated that allele -2604A confers a higher DNA binding capacity to transcription factors of the GATA family. Conclusions: The presence of allele -2604A is associated to a diminished level of gene expression in peripheral blood of patients with advanced carotid atherosclerotic plaques, possibly by creating a transcription factor binding site for a negative modulator(s) of transcription. Case/control studies in larger populations are worthy to determine if variants of polymorphism -2604A>G of TLR4 might represent a genetic risk factor for susceptibility to atherosclerotic plaque development and progression.