Expression of toll-like receptor 4 gene polymorphism and inflammatory factors in peripheral blood on patients with sepsis

Abstract

Objective: To observe the presence of toll-like receptor 4 (TLR4) gene polymorphism in the venous blood in patients with sepsis, meanwhile, to observe the expression and the diagnostic value of TLR4 mRNA, interferon-γ (IFN-γ), interleukin-23 (IL-23), procalcitonin (PCT) and C-reactive protein (CRP) in patients with different degrees of sepsis.

Methods: The peripheral blood samples from the subjects were collected to extract genomic DNA, gene sequencing and enzyme digestion method were applied to the detection of TLR4 Asp299Gly loci polymorphism. The expression of TLR4 mRNA in the peripheral blood was detected by reverse transcriptase polymerase chain reaction (RT-PCR). The expression levels of IFN-γ, IL-23, PCT and CRP were measured by enzyme linked immunosorbent assay (ELISA).

Results: (1) The gene polymorphism was not present in TLR4 Asp299Gly loci; (2) The expression of TLR4 mRNA in the peripheral blood in patients with sepsis: on d1, there were statistically significant differences between the normal group and the group (APACHE II ≤ 20), between the normal group and the group (APACHE II > 20), between the group (APACHE II ≤ 20) and the group (AAPACHE II > 20) (t = 5.741, 14.780 and 10.500, all p < .01). APACHE II stands for Acute Physiology and Chronic Health Evaluation II. On d7, there were statistically significant differences between the normal group and the group (APACHE II ≤ 20), between the normal group and the group (APACHE II > 20), between the group (APACHE II ≤ 20) and the group (APACHE II > 20) (t = 4.186, 13.830 and 9.645, all p < .01); (3) The expression levels of IFN-γ, IL-23, PCT and CRP were obviously upregulated (all p < .01), and TLR4 was positively correlated with IFN-γ and IL-23 (all p < .01); (4) The best cutoff value of TLR4 mRNA at baseline was 891.6 μg/L, with a sensitivity of 100% and a diagnostic specificity of 57%. The best cutoff value of IFN-γ at baseline was 84.5 μg/L, with a sensitivity of 100% and a diagnostic specificity of 57%. The best cutoff value of IL-23 at baseline was 861 μg/L, with a sensitivity of 100% and a diagnostic specificity of 97%.

Conclusions: (1) The Asp299Gly polymorphism is not present in TLR4 gene; (2) The expression levels of TLR4 mRNA, IFN-γ and IL-23 are relatively high in patients with sepsis, and will be higher with the increased severity of sepsis; (3) TLR4 mRNA, IFN-γ and IL-23 can be used as molecular biomarkers for the early diagnosis of sepsis.