Study On The Association Of Toll-like Receptor 9 And Its Signaling Pathway Polymorphisms With The Outcomes Of Hepatitis B Virus Infection

【Objective】Toll-like receptors are the major receptors of host's innate immune response and function like a vinculum between the innate and acquired immunity. Activation of the TLR9 signaling pathway can induce production of lots of cytokines, so it probably plays an important role in defending hepatitis B virus infection. However, few studies have reported whether the TLR9 and its signaling pathway polymorphisms were associated with the clinical outcomes of hepatitis B virus infection. In this study, the SNPs within the TLR9 and myeloid differentiation primary response protein 88(MyD88) genes were analyzed in different groups, then to evaluate their relationship with the clinical outcomes of HBV infection.【Methods】Totally,103 HBV associated acute on chronic liver failure,156 chronic hepatitis B(CHB) patients and 151 cases of HBV spontaneous clearance persons were enrolled in this study. NCBI database of Chinese Han population was used to select the candidate genes' SNPs, which contain three sites within TLR9 gene promoter region including rs352144(A/C),rs187084(T/C),rs5743836(T/C) and two sites within MyD88 gene 3'untranslated region (3'UTR) rs7744(A/G) and rs6853(A/G). PrimerPremier5 and vector NTI 10 software were used to design the primer sequences for PCR. Human genomic DNA was extracted from peripheral blood mononuclear cells. The genotypes were analyzed using real-time fluorescence quantitative polymerase chain reaction(real-time PCR) and then the differences of genotype and allele distributions among groups were compared.【Results】1.The frequency of genotype AC at the position rs352144(A→C) within TLR9 gene in CHB patients was significantly lower than that of HBV spontaneous clearance cases(3.8% VS 11.3%,P<0.05),the frequency of allele C was 1.9% VS 5.6%( P<0.05), the odds ratio(OR) value was 3.042, and the 95% confidence intervals(CI) was 1.183 to 7.824. However, no significant difference was found between acute on chronic liver failure patients and spontaneous clearance cases(P>0.05), the OR value was 1.306, and the 95% CI was 0.57 to 2.989. There were no differences in genotype and allele distributions of rs187084(T→C) neither between acute on chronic liver failure group and HBV spontaneous clearance group, nor between CHB group and HBV spontaneous clearance group, the OR value was 1.175 and 1.114, respectively, and the 95% CI was 0.816 to 1.692 and 0.806 to 1.541,respectively. Similarly, no differences were observed at rs5743836(T→C), the OR value was 0.68 and 1.007, respectively, and the 95%CI was 0.095 to 4.866 and 0.997 to 1.106, respectively. 2.The frequency of genotype GG at the position of rs7744(A→G) within MyD88 gene in acute on chronic liver failure patients was significantly higher than that of HBV spontaneous clearance group (45.6% VS 21.2%, P<0.01), the OR value was 0.555, and the 95%CI was 0.388 to 0.794, but no difference was observed between CHB group and spontaneous clearance group(P>0.05), the OR value was 0.891, and the 95%CI was 0.647 to 1.227. There were no differences in genotype and allele distributions of rs6853(A→G) neither between acute on chronic liver failure group and HBV spontaneous clearance group, nor between CHB group and spontaneous clearance group, the OR value was 1.617 and 0.722, respectively, and the 95% CI was 0.413 to 6.326 and 0.271 to 1.921, respectively.【Conclusion】1. Genotype AC at TLR9 gene rs352144(A→C) site is associated with HBV spontaneous clearance, but not correlated with chronic HBV infection and liver failure. There are no correlation between polymorphisms of SNP rs187084(T→C),rs5743836(T→C) and the clinical outcomes of HBV infection. 2. The rs7744(A→G) single nucleotide polymorphisms within MyD88 gene might play an important role in the pathogenesis of liver failure. The patients who carry GG genotype may develop to acute on chronic liver failure more likely. No correlation is found between polymorphisms of SNP rs6853(A→G) and the clinical outcomes of HBV infection.