Genetic and phenotypic difference in CD8(+) T cell exhaustion between chronic hepatitis B infection and hepatocellular carcinoma

BACKGROUND: Several recent studies published have suggested that T cell exhaustion exists both in chronic infection and cancer. However, to date, few studies have investigated their differences. Here we designed this study to explore the genetic and phenotypic difference in CD8(+) T cell exhaustion between chronic hepatitis B (CHB) and hepatocellular carcinoma (HCC). METHODS: In this study, we assayed the phenotypes and functional states of CD8(+) T cells separating from human CHB tissues and HCC tissues, and re-analyse the single-cell sequencing data (GSE98638) published previously. Clustering analysis of genes was performed using the T cell exhaustion gene modules (modules 1–4) proposed by Speiseret al. RESULTS: CD8(+) T cells from liver tissues of both CHB and HCC showed high levels of exhaustion markers, DOI: programmed cell death-1 (PD-1), T-cell immunoglobulin and mucin-domain containing-3 (TIM-3), cytotoxic T lymphocyte-associated antigen-4 (CTLA-4), and lymphocyte-activation gene 3 (LAG-3), decreased proliferation (Ki67) and cell activity (CD69), and reduced production of effector cytokines (interferon-γ, interleukin-2 and tumour necrosis factor-α). Compared with CD8(+) T cells from CHB tissues, those from HCC tissue showed higher expression levels of exhaustion markers, lower levels of proliferation, cell activity and the production of effector cytokines. Cluster analysis showed that exhaustion associated genes in CHB and HCC are inclined to distribute into modules 3 while those isolated from HCC into modules 1 and 2. CONCLUSIONS: CD8(+) T cell exhaustion existed both in CHB and HCC, but the phenotypes, functional states and underlying mechanisms are somewhat different between the two.