Circulating level of sPD-1 and PD-1 genetic variants are associated with hepatitis B infection and related liver disease progression.

BACKGROUND: Programmed cell death-1 (PD-1) variants and circulating level of soluble PD-1 are associated with susceptibility to malignant and infectious disease. This study aimed to examine the association of PD-1.5 and PD-1.9 variants, and plasma sPD-1 level with hepatitis B virus (HBV) infection and disease progression. METHODS: The study cohort consisted of adults infected with HBV (n=513) - stratified by clinical course, including chronic hepatitis B (CHB, n=173), liver cirrhosis (LC, n=134) and hepatocellular carcinoma (HCC, n=206) - and matched healthy controls (HC, n=196). The PD-1.5 (rs2227981 C/T) and PD-1.9 (rs2227982 C/T) genetic variants were genotyped by Sanger sequencing, and plasma sPD-1 levels were quantified by enzyme immunoassay. RESULTS: Plasma sPD-1 levels were significantly higher among patients infected with HBV. The highest plasma sPD-1 levels were observed in patients with CHB, followed by patients with LC and HCC. In addition, the plasma sPD-1 levels correlated positively with liver inflammation [aspartate transaminase (AST): rho=0.57, P<0.0001; alanine aminotransferase: rho=0.57, P<0.0001], and were positively correlated with liver fibrosis [AST to platelet ratio index score: rho=0.53, P<0.0001). The PD-1.9 TT genotype was less common in patients with CHB compared with patients with LC, HCC, and HCC+LC in both codominant and recessive models (P<0.01), and was found to be a risk factor for HCC predisposition {HCC vs non-HCC: odds ratio (OR) 2.0 [95% confidence interval (CI) 1.13-3.7], Padj=0.017}. The PD-1.5 CT genotype was associated with reduced risk of acquiring HCC [OR 0.6 (95% CI 0.4-0.9), Padj=0.031]. CONCLUSION: sPD-1 level was associated with liver inflammation and progression of liver fibrosis, and the PD-1.5 and PD-1.9 variants were associated with HBV infection and progression of liver disease.

Genetic variants of programmed cell death 1 are associated with HBV infection and liver disease progression.

The inhibitory effects of programmed cell death 1/programmed cell death ligand 1 (PD-1/PD-L1) modulates T-cell depletion. T-cell depletion is one of the key mechanisms of hepatitis B virus (HBV) persistence, in particular liver disease progression and the development of hepatocellular carcinoma (HCC). This case-control study aimed to understand the significance of PD-1 polymorphisms (PD-1.5 and PD-1.9) association with HBV infection risk and HBV-induced liver disease progression. Genotyping of PD-1.5 and PD-1.9 variants was performed by direct Sanger sequencing in 682 HBV-infected patients including chronic hepatitis (CHB, n = 193), liver cirrhosis (LC, n = 183), hepatocellular carcinoma (HCC, n = 306) and 283 healthy controls (HC). To analyze the association of PD-1 variants with liver disease progression, a binary logistic regression, adjusted for age and gender, was performed using different genetic models. The PD-1.9 T allele and PD-1.9 TT genotype are significantly associated with increased risk of LC, HCC, and LC + HCC. The frequencies of PD-1.5 TT genotype and PD-1.5 T allele are significantly higher in HCC compared to LC patients. The haplotype CT (PD-1.5 C and PD-1.9 T) was significantly associated with increased risk of LC, HCC, and LC + HCC. In addition, the TC (PD-1.5 T and PD-1.9 C) haplotype was associated with the risk of HCC compared to non-HCC. The PD-1.5 CC, PD-1.9 TT, genotype, and the CC (PD-1.5 C and PD-1.9) haplotype are associated with unfavorable laboratory parameters in chronic hepatitis B patients. PD-1.5 and PD1.9 are useful prognostic predictors for HBV infection risk and liver disease progression.