Differential gene expression in peripheral blood between low viremic inactive carrier and NUC-treated HBV patients irrespective of circulating HBsAg levels

Monocyte Transcriptome in Different Phases of Chronic Hepatitis B Virus Infection Uncovers Potential Functional Roles

The hepatitis B virus (HBV) chronic infection goes through different phases, i.e., immune tolerant (IT), immune clearance (IC), and inactive carrier (IN) resulting from the interplay of viral replication and immune response. Although the adaptive immune response is central to viral control, roles of the innate immune cells are less prominent. We explored monocyte transcriptome in these different phases of HBV infection to understand the nature of its involvement and identify unique differentially expressed genes (DEGs) in each phase. CD14+ peripheral blood monocytes were isolated from patients in the IT, IC, and IN phases and from healthy subjects and their RNA was sequenced. The significant DEGs were studied through gene annotation databases to understand differentially modulated pathways. The DEGs were further validated by qRT-PCR to identify genes that were uniquely expressed in each phase. It was found that TNFRSF12A was upregulated in all the HBV samples. The IN phase had six uniquely upregulated genes, i.e., PI3, EMP1, STX1A, RRAD, SPINK1, and SNORD3B-2. E2F7 was most consistently downregulated in the IT phase, and in the IC phase, IL23A and PI3 were specifically downregulated. Cut-off values were generated by ROC curve analysis to differentiate between the groups based on their expression levels. The monocyte functions are majorly suppressed in the IT and IC phases and are, however, somewhat metabolically active in the IN phase.

Association of HBsAg levels with differential gene expression in NK, CD8 T, and memory B cells in treated patients with chronic HBV

Background & Aims

HBsAg secretion may impact immune responses to chronic HBV infection. Thus, therapeutic approaches to suppress HBsAg production are being investigated. Our study aims to examine the immunomodulatory effects of high and low levels of circulating HBsAg and thereby improve our understanding of anti-HBV immunity.

Methods

An optimized 10x Genomics single-cell RNA sequencing workflow was applied to blood samples and liver fine-needle aspirates from 18 patients undergoing tenofovir/entecavir (NUC) treatment for chronic HBV infection. They were categorized based on their HBsAg levels: high (920-12,447 IU/ml) or low (1-100 IU/ml). Cluster frequencies, differential gene expression, and phenotypes were analyzed.

Results

In the blood of HBV-infected patients on NUC, the proportion of KLRC2+ "adaptive" natural killer (NK) cells was significantly lower in the HBsAg-high group and, remarkably, both KLRC2+ NK and KLRG1+ CD8 T cells display enrichment of lymphocyte activation-associated gene sets in the HBsAg-low group. High levels of HBsAg were associated with mild immune activation in the liver. However, no suppression of liver-resident CXCR6+ NCAM1+ NK or CXCR6+ CD69+ CD8 T cells was detected, while memory B cells showed signs of activation in both the blood and liver.

Conclusions

Among NUC-treated patients, we observed a minimal impact of HBsAg on leukocyte populations in the blood and liver. However, for the first time, we found that HBsAg has distinct effects, restricted to NK-, CD8 T-, and memory B-cell subsets, in the blood and liver. Our findings are highly relevant for current clinical studies evaluating treatment strategies aimed at suppressing HBsAg production and reinvigorating immunity to HBV.

Impact and implications

This study provides unique insight into the impact of HBsAg on gene expression levels of immune cell subsets in the blood and liver, particularly in the context of NUC-treated chronic HBV infection. It holds significant relevance for current and future clinical studies evaluating treatment strategies aimed at suppressing HBsAg production and reinvigorating immunity to HBV. Our findings raise questions about the effectiveness of such treatment strategies and challenge the previously hypothesized immunomodulatory effects of HBsAg on immune responses against HBV.