Study of the relationship between TLR4 gene polymorphism and sepsis.

Abstract

Objective To study the 2244G→A, 2299 A→G single nucleotide polymorphism (SNP) in the 5' regulatory regions of Toll-like receptor 4 (TLR4) in patients with Gram negative bacteria infection in Shenzhen locality, and to discuss the occurrence, course and prognosis of patients with sepsis. Method Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used to detect the genotype of TLR4. After the whole blood DNA of patient was extracted and PCR was amplified, the products were 500bp and 599 bp, and were cut by endonuclease Mae Ⅱ and Sph Ⅰ respectively to determine the SNP 2244G→A and 2299 A→G in TLR4. These two kinds of allele frequencies were statistically calculated in all patients. In the meantime, the incidence of septic shock, average hospitalized days, cost and prognosis of all patients were recorded. Statistical analysis was performed with SPSS version 16 software. ANOVA was used for comparison among multiple groups, and t -test and Sighed rank test were used for paired comparison. Results The 2299 and 2244 sites in the 5' regulatory regions of TLR4 gene of patients with Gram negative bacteria infection in Shenzhen locality had various degrees of changes in single nucleotide. Compared with the documented data from Chinese people in general, there was a significant difference in 2299A→G genotype frequency in residents of Shenzhen locality ( P < 0.05). But there were no statistically significant difference in mortality, incidence of septic shock, average days of ICU stay or ICU cost between TLR4 SNP positive and negative groups of patients. Conclusions There is a wide range of genetic variation in the 2299 and 2244 sites in the 5' regulatory regions of TLR4 among citizens of Shenzhen locality with unique distribution. The 2299A→G genotype frequency probably has differences in distribution and population. The pathogenesis and the prognostic factors of sepsis are complicated, whereas the gene polymorphism may be just one of the factors affecting the prognosis of patients with Gram negative bacteria infection. Key words: Toll-like receptor 4 (TLR4); Gene polymorphism; Lipopolysaccharide; Sepsis; Gran negative bacteria infection