The TLR8 agonist Selgantolimod regulates Kupffer cell differentiation status and indirectly impairs HBV entry into hepatocytes via an IL-6-dependent mechanism (PHH) [Kupffer cells]

Background & Aims: In spite of universal vaccination programs, HBV remains a global burden due to the limited therapeutic options available. Therefore, achieving the goal of HBV cure will require a continuous effort to develop novel molecules and combination therapies. In this context, the Toll-like receptor 8 (TLR8) agonist selgantolimod (SLGN) has shown promising results during its clinical evaluation. Although the effect of SLGN has been explored in the peripheral immune compartment, little is known regarding its intrahepatic response. Therefore, we characterized the transcriptomic changes and intercellular communication events associated with SLGN in the liver microenvironment. Approach & Results: The analysis of single-cell RNA sequencing (scRNA-seq) data allowed us to identify that hepatic TLR8 expression takes place in the myeloid compartment. Therefore, we stablished a method for the isolation of human Kupffer cells (KCs). We found that in vitro treatment of KCs with SLGN induces the upregulation of monocyte markers (e.g., EREG, S100A12) and the downregulation of genes associated with the KC identity (e.g., SPIC, FOLR2). Moreover, treatment of hepatocytes with SLGN-conditioned media (CM) led to the downregulation of NTCP and impaired HBV entry. Finally, co-treatment with SLGN-CM and an IL-6-inhibitory antibody identified this cytokine as mediating the reduced HBV entry. Conclusions: Our results suggest that in addition to its previously described therapeutic activity against HBV, SLGN also presents a prophylactic effect. Furthermore, our characterization of SLGN sheds light into the transcriptional programs regulating KC activation and underscores the importance of considering cell states when annotating cell populations based on scRNA-seq data. Overall design: RNA-seq profiles from human Kupffer cells (KCs) exposed (24 h) to selgantolimod (SLGN, 150 nM, n=3) or DMSO (n=3).