Journal Article

Retreatment with HBV siRNA Results in Additional Reduction in HBV Antigenemia and Immune Stimulation in the AAV-HBV Mouse Model

Pierson, Wim, Verschueren, Lore, Krishna, Vinod, Nájera, Isabel, Vleeschouwer, Mara, Van Gulck, Ellen, Aerts, Liese, Pauwels, Frederik, Conceição-Neto, Nádia

2024

Overview

Background and Aims: Treatment with siRNAs that target HBV has demonstrated robust declines in HBV antigens. This effect is also observed in the AAV-HBV mouse model, which was used to investigate if two cycles of GalNAc-HBV-siRNA treatment could induce deeper declines in HBsAg levels or prevent rebound, and to provide insights into the liver immune microenvironment. Methods: C57Bl/6 mice were transduced with one of two different titers of AAV-HBV for 28 days, resulting in stable levels of HBsAg of about 103 or 105 IU/mL. Mice were treated for 12 weeks (four doses q3wk) per cycle with 3 mg/kg of siRNA-targeting HBV or an irrelevant sequence either once (single treatment) or twice (retreatment) with an 8-week treatment pause in between. Blood was collected to evaluate viral parameters. Nine weeks after the last treatment, liver samples were collected to perform phenotyping, bulk RNA-sequencing, and immunohistochemistry. Results: Independent of HBsAg baseline levels, treatment with HBV-siRNA induced a rapid decline in HBsAg levels, which then plateaued before gradually rebounding 12 weeks after treatment stopped. A second cycle of HBV-siRNA treatment induced a further decline in HBsAg levels in serum and the liver, reaching undetectable levels and preventing rebound when baseline levels were 103 IU/mL. This was accompanied with a significant increase in inflammatory macrophages in the liver and significant upregulation of regulatory T-cells and T-cells expressing immune checkpoint receptors. Conclusions: Retreatment induced an additional decline in HBsAg levels, reaching undetectable levels when baseline HBsAg levels were 3log10 or less. This correlated with T-cell activation and upregulation of Trem2.

• Publisher: MDPI AG,MDPI
• Subject: Animals / Antigenemia / Antigens / Antiviral Agents - therapeutic use / blood serum / Care and treatment / Cell activation / decline / Development and progression / DNA, Viral / Ethics / Genomes / Hepatitis associated antigen / Hepatitis B / Hepatitis B surface antigen / Hepatitis B Surface Antigens / Hepatitis B virus - genetics / hepatitis surface antigen / Immune checkpoint / Immunohistochemistry / Immunotherapy / Inflammation / Liver / Liver cancer / Lymphocytes T / Macrophages / Measurement / Membrane Glycoproteins / Mice / Microenvironments / phenotype / Phenotyping / Receptors, Immunologic / Retreatment / RNA, Small Interfering - genetics / sequence analysis / sequencing / siRNA / T-cell exhaustion / T-lymphocytes / Testing / Trem2 / Up-regulation / Veins & arteries