Anti–PD-L1–IFN-α–adjuvanted HBsAg vaccine overcomes HBV immune tolerance through targeting both DCs and macrophages
Chao-Yang Meng, Yong Liang, Longxin Xu, Hongjia Li, Jingya Guo, Hairong Xu, Fan Wang, Yang-Xin Fu, Hua Peng
Chao-Yang Meng, Yong Liang, Longxin Xu, Hongjia Li, Jingya Guo, Hairong Xu, Fan Wang, Yang-Xin Fu, Hua Peng
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Research Article Hepatology Immunology Virology

Anti–PD-L1–IFN-α–adjuvanted HBsAg vaccine overcomes HBV immune tolerance through targeting both DCs and macrophages

Abstract

Recombinant hepatitis B surface antigen (rHBsAg) vaccine with various adjuvants fails to break T and B cell tolerance in hosts with chronic hepatitis B (CHB). This study aims to explore the mechanisms to break immune tolerance that allows the host to respond to rHBsAg, achieving a cure for CHB. We engineered an anti–PD-L1–IFN-α (aPD-L1–IFN-α) heterodimeric fusion protein to allow rHBsAg to rejuvenate T and B cell responses in hepatitis B virus–tolerant (HBV-tolerant) mice. S.c. coimmunization with aPD-L1–IFN-α and rHBsAg significantly enhanced antigen uptake and maturation of both macrophage and dendritic cell (DC) subsets in draining lymph nodes. Macrophages drove early B cell activation, while cDC1s primed CD8+ T cells, breaking tolerance and leading to both B cell and cytotoxic T lymphocyte (CTL) differentiation. This strategy elicited not only anti-HBsAg neutralizing antibodies but also HBsAg-specific CD8+ T cell responses, achieving a functional cure without systemic toxicity. The efficacy of the aPD-L1–IFN-α adjuvant depended on both PD-L1 cis-targeting and IFN-α receptor signaling in antigen-presenting cells. These findings establish aPD-L1–IFN-α as a translatable adjuvant to break the strong tolerance induced by CHB, providing a dual-pathway strategy to induce HBV-specific T and B cell responses.

Authors

Chao-Yang Meng, Yong Liang, Longxin Xu, Hongjia Li, Jingya Guo, Hairong Xu, Fan Wang, Yang-Xin Fu, Hua Peng

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Figure 3

The coimmunization achieves a functional cure in HBV-tolerant mice.

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The coimmunization achieves a functional cure in HBV-tolerant mice. (A) ...
(A) Time schedule for aPD-L1–IFN-α mixed with rHBsAg as a therapeutic vaccine to treat HBV carrier mice. aPD-L1–IFN-α (2 μg/mouse) was mixed with rHBsAg (1 μg/mouse) (denoted as aPD-L1–IFN-α mix rHBsAg, coimmunization) and injected s.c. into HBV carrier mice. A second immunization with the same mixture was given 7 days after the initial immunization, followed by booster immunizations with rHBsAg alone at 3 and 5 weeks after initial immunization. The control group received rHBsAg (1 μg/mouse) s.c. injection into HBV carrier mice on days 0, 7, 21, and 35. (B and C) Serum levels of ayw subtype–specific anti-HBsAg IgG (B) and HBsAg (C) (n = 5/group) were examined by ELISA. (D) Serum levels of HBV-DNA (n = 5/group) were determined by qPCR. The detection limits in C and D are indicated by dashed lines. (E–G) A total of 1 × 106 splenocytes from each mouse (n = 5/group) were collected on day 132. Specific B cell (E) and T cell (F) responses to HBsAg (subtype ayw) were tested by B cell and T cell ELISpot assays, respectively. ENV190-specific CD8+ T cell responses were tested by a T cell ELISpot assay (G). (H–J) Levels of HBV intermediate products, including HBV 3.5-kb RNA (H), HBV total RNA (I), and HBV DNA (J) in the liver, were measured with real-time PCR at the end of the experiment (n = 5/group). Data are shown as the mean + SEM (B and C) or mean ± SEM (D–J) and are representative of at least 2 independent experiments. An unpaired 2-tailed Student’s t test was applied in D–G. One-way ANOVA followed by Tukey’s test was applied in B and H–J. **P < 0.01; ***P < 0.001; ****P < 0.0001. OD, optical density; s.c., s.c.