T cell dysfunction in chronic hepatitis B infection and liver cancer: evidence from transcriptome analysis.

Background: T cell dysfunction occurs in many diseases, especially in chronic virus infection and cancers. However, up to now, little is known on the distinctions in T cell exhaustion between cancer and chronic virus infection. The objective of this study is to explore the transcriptional similarities and differences in exhausted CD8 +T cell between chronic hepatitis B virus (HBV) infection and hepatocellular carcinoma (HCC).

Methods: RNA sequencing was performed to compare the transcriptome of CD8 +T cells isolated from healthy donors' blood, tumour tissues of patients with HCC and chronic HBV infected HCC patients' paracancerous tissues. DESeq2 algorithm was used to determine differentially expressed genes. Gene ontology and Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway enrichment analysis was conducted for in-depth analysis of these differentially expressed genes.

Results: A total number of 2109 and 2203 genes were differentially expressed in patients with chronic HBV infection and HCC, respectively. Comparing these two groups of differentially deregulated genes, we found that nearly half of them were shared, and these shared genes were further classified into several functional categories, such as metabolic process, binding and intracellular organelle. KEGG analysis revealed that these shared deregulated genes were involved in many important pathways such as Parkinson's disease, oxidative phosphorylation and messenger RNA surveillance. Interestingly, we reported that chronic HBV infection specific deregulated genes were mainly enriched in graft versus host disease, allograft rejection, phenylalanine, tyrosine and tryptophan biosynthesis pathways. Whereas, HCC-specific deregulated genes were highly enriched in oxidative phosphorylation, thyroid cancer and endometrial cancer pathways.

Conclusion: Our study demonstrated that T cell dysfunction associated with HCC and chronic HBV infection shares high similarities, however, each possesses its own features in terms of specific genes and signalling pathways. Uncovering the differences of T cells dysfunction would facilitate our understanding the diseases pathogenesis and developing innovative therapies in the future.