Hepatitis B & D - Experimental
DIRECT ANTIVIRAL EFFECTS OF VARIOUS PATTERN RECOGNITION RECEPTOR (PRR) AGONISTS IN HBV-REPLICATING HEPATOCYTES
Julie Lucifora1, 2, Sarah Maadadi2, 3, Océane Floriot1, 2, Stephane Daffis4, Simon Fletcher4, Fabien Zoulim1, 2, 5, David Durantel* 1, 2
1U1052, INSERM, 2UCBL, University of Lyon, 3INSERM, U1052, Lyon, France, 4Gilead Sciences, Foster City, United States, 5Liver unit, Hospices Cilvils de Lyon, Lyon, France
Corresponding author’s email: david.***@****
Background and Aims: Current therapies for chronic hepatitis B virus (HBV) infection are effective at suppressing viral replication and improve long-term outcome, but have only low rates of HBsAg loss and anti-HBs seroconversion. There is an urgent need to identify new antiviral therapies to achieve functional cure and so decrease the risk of end-stage liver disease. Studies with the oral TLR7 agonist GS-9620 in animal models of chronic hepatitis B (CHB) have recently highlighted the potential of therapeutic immune modulation by small molecule agonists of innate immunity. To further explore the potential of PRR agonists to induce efficient and durable immune control against HBV, we tested the direct anti-HBV effect of different PRR agonists in cell culture models of natural infection.
Methods: Primary human hepatocytes (PHH) and differentiated HepaRG cells (dHepaRG), which are both innate immune competent cells, were infected with HBV for 7 days, and then treated with various concentrations of different PRR agonists for 7 days. Antiviral activity was evaluated by quantifying HBeAg and HBsAg secretion (ELISA), HBV RNA (qRT-PCR) and total intracellular HBV DNA and cccDNA (qPCR), and toxicity measured by MTS assay and ApoB ELISA. Cytokine production was evaluated by ELISA 24 hours (h) post-stimulation.
Results: The cytokines IP-10 and/or IL-6 were secreted by both PHH and dHepaRG 24h after stimulation with TLR1/2, TLR3, TLR4, TLR5, TLR2/6, RIG-I/MDA5, and AIM2 agonists, which correlated with a strong and dose-dependent antiviral effect in the absence of toxicity. The maximal antiviral effect was induced by Pam3CSK4 (i.e. TLR1/2-L), which induced sustained reduction in all viral parameters, including levels of cccDNA. Stimulation with TLR7, TLR8 and TLR9 agonists did not significantly induce IP-10 or IL-6 production and, with the exception of imiquimod, did not inhibit HBV replication. Interestingly, the antiviral response induced by imiquimod was independent of innate immune activation, suggesting an additional mode of action that should be further investigated.
Conclusions: Our data highlight the potential of direct innate immunity activation in hepatocytes in the control of HBV replication, and support the recent interest in the development of PRR-based antiviral strategies against HBV. In addition, our data suggest that elucidation of the mode of antiviral action of imiquimod may lead to the identification of a novel target for the treatment of CHB.
Disclosure of Interest: J. Lucifora: Grant: Gilead, S. Maadadi: : None Declared, O. Floriot: : None Declared, S. Daffis: Employee: Gilead Sciences, S. Fletcher: Employee: Gilead Sciences, F. Zoulim: Grant: Gilead Sciences, D. Durantel: Grant: Gilead Sciences