An Engineered DC-Targeting Lentivector Induces Robust T Cell Responses and Inhibits HBV Replication in HBV Transgenic Mice via Upregulating T Cell Autophagy

Abstract

Background/Aims: Developing engineered dendritic cell (DC)-targeting lentivectors (LVs) have been the target of intense research for their potential to create antigen-directed immunotherapeutics which can be safely administered to patients. In this study, we constructed a DC-directed LV (LVDC-UbHBcAg-LIGHT) as a potential vaccine to induce anti-HBV immune responses. Methods: Specificity of LVDC-UbHBcAg-LIGHT for DCs in vivo was confirmed through live animal imaging studies. The levels of cytokine production in T cells were assessed by flow cytometry. The HBcAg-specific cytotoxic T lymphocyte (CTL) responses and antibody responses induced by direct administration of the LVs were detected by LDH release assay and ELISA respectively. The levels of serum HBsAg and HBV DNA were evaluated by Abbott kits and quantitative PCR respectively. The expression levels of HBsAg and HBcAg in liver tissues of HBV transgenic mice were examined by immunohistochemistry. In addition, molecular mechanism underlying the activation of CD8+ T cells was explored. Results: Live animal imaging studies showed that following subcutaneous administration of LVDC-UbHBcAg-LIGHT, no obvious luminescence signal was detected at the injection site. Immunization with LVDC-UbHBcAg-LIGHT elicited potent T cell responses in HBV transgenic mice evidenced by increased percentages of IFN-γ, TNF-α and GzmB producing CD8+ T cells as well as IFN-γ producing CD4+ T cells, improved HBcAg-specific CTL activities and antibody responses. Additionally, vaccination with LVDC-UbHBcAg-LIGHT efficiently reduced serum HBsAg, HBV DNA levels and the expression of HBsAg and HBcAg in liver tissues of HBV transgenic mice. More importantly, autophagy was induced in the activated CD8+ T cells, and the induced autophagy noticeably promoted the proliferation of T cells and decreased the frequencies of apoptotic CD8+ T cells by selectively degrading ubiquitinated apoptosis and cell cycle-associated protein aggregates. Futhermore, we confirmed the interaction between autophagosomes and ubiquitinated aggregates by confocal microscopy and immunoprecipitation analysis. Conclusions: These results demonstrated that LVDC-UbHBcAg-LIGHT provided a simple method of eliciting effective antiviral immune responses in HBV transgenic mice and might potentially be used as a therapeutic strategy to eradicate HBV with more safety and efficiency. Moreover, our results revealed a direct role of autophagy in promoting the survival and proliferation of activated CD8+ T cells.

The microRNA‐155 mediates hepatitis B virus replication by reinforcing SOCS1 signalling–induced autophagy

“…Autophagy was regarded as a remarkable contributor to HBV replication, confirmed via independent studies showing that autophagy inhibition strongly impaired replication of HBV in liver cells . Furthermore, it has been shown that autophagy deficiency noticeably represses HBV replication in transgenic mice and that autophagy was necessary for HBV envelopment, despite being unnecessary for HBV release . Our research shows that miR‐155 positively modulated HBV replication, similar to previous studies.…”

Research Progress on the Mechanism of Persistent Low-Level HBsAg Expression in the Serum of Patients with Chronic HBV Infection

“…As an APC, DCs can absorb and process HBsAg and secrete a variety of cytokines to participate in the regulation of immune tolerance and immune responses in patients with chronic HBV infection [ 77 ]. At the same time, the liver contains different nonparenchymal cell populations, which can also be used as APCs.…”

Interplay between Cellular Autophagy and Hepatitis B Virus Replication: A Systematic Review

“…Autophagy is essential for HBV-specific adaptive immune responses. Ma et al demonstrated the ability of a lentivector-targeting engineered dendritic cell (DC) to induce robust T-cell responses and elicit effective anti-HBV effect in HBV transgenic mice [68,69]. They further revealed that the upregulation of the autophagy of T cells aids in the eradication of HBV by promoting the survival and proliferation of activated CD8 + T cells.…”

“…Ma et al constructed a DC directed against a lentivector (LV) (LVDC-UbHBcAg-LIGHT) for use as a potential vaccine to induce anti-HBV immune responses. They found that the vaccine elicited effective anti-HBV effects in HBV transgenic mice [68,69]. Further study revealed that the increased autophagy of T cells primarily contributed to the elimination of HBVs.…”