HBV-driven host chromatin accessibility changes affect liver metabolic pathways, iron homeostasis and promote a preneoplastic phenotype [ATAC-seq]
Background and Aims: Complex host-virus interactions account for HBV-specific T and B cells dysfunction and the persistence of the viral cccDNA mini-chromosome, key features of HBV chronicity and challenges for HBV cure. The extent of HBV impact on liver transcriptome remains controversial. Transcriptional activation in eukaryotic cells has been tightly linked with disruption of nucleosome organization at accessible genomic sites of remodeled chromatin. We used ATAC-seq (Assay for Transposase Accessible Chromatin followed by high throughput sequencing) to detect early changes in chromatin accessibility in HBV-infected Primary Human Hepatocytes (PHHs). Results. ATAC-seq analysis revealed that after HBV infection an increasing number of genomic sites change their chromatin accessibility over time with a prevalent global reduction of accessibility (that is) partially prevented by inhibiting HBV transcription and replication. Motif Enrichment Analysis identified several TF involved in liver cell identity, glucose and lipid metabolism as potential regulators of differentially accessible genes 72h post-infection, when cccDNA transcription and viral replication are established. ATAC-seq and RNA-seq integration confirmed HBV infection impact on liver metabolism, the early establishment of a premalignant phenotype and identified a 39-genes liver iron signature modulated by chromatin accessibility changes. The upregulation of iron uptake genes translates in a significant increase of iron content in HBV-infected PHHs whereas iron chelation results in a drastic inhibition of cccDNA transcription and viral replication. Conclusions. Altogether our results show that HBV infection impacts on host cell chromatin landscape and specific transcriptional programs and that HBV modulates intracellular available iron to boost its replication. Overall design: Primary Human Hepatocytes (PHHs) from 2 donors were infected with HBV, left un-infected (Mock) or infected with HBV and treated with interferon (INF) and cultured for 2h and 72h. Assay for Transposase-Accessible Chromatin (ATAC) was performed and sequenced on a NextSeq 500 Illumina platform.