Enhanced activation of human NK cells by drug-exposed hepatocytes

Frank Fasbender,Carsten Watzl,Martin Obholzer,Jan G Hengstler,Regina Stöber,Sarah Metzler

doi:10.1007/s00204-020-02668-8

Abstract

Drug-induced liver injury (DILI) represents one of the major causes why drugs have to be withdrawn from the market. In this study, we describe a new interaction between drug-exposed hepatocytes and natural killer (NK) cells. In a previous genome-wide expression analysis of primary human hepatocytes that had been exposed to clinically relevant concentrations of 148 drugs, we found that several activating ligands for NK cell receptors were regulated by various drugs (e.g., valproic acid, ketoconazole, promethazine, isoniazid). Especially expression of the activating NKG2D ligands (MICA, MICB and ULBPs) and the NKp30 ligand B7-H6 were upregulated in primary human hepatocytes upon exposure to many different drugs. Using the human hepatocyte cell lines Huh7 and HepG2, we confirmed that protein levels of activating NK cell ligands were elevated after drug exposure. Hepatocyte cell lines or primary human hepatocytes co-cultivated with NK cells caused enhanced NK cell activation after pretreatment with drugs at in vivo relevant concentrations compared to solvent controls. Enhanced NK cell activation was evident by increased cytotoxicity against hepatocytes and interferon (IFN)-γ production. NK cell activation could be blocked by specific antibodies against activating NK cell receptors. These data support the hypothesis that NK cells can modulate drug-induced liver injury by direct interaction with hepatocytes resulting in cytotoxicity and IFN-γ production.

Highlights

Drug-induced liver injury (DILI) is one of the major challenges in drug development. (Godoy et al 2013)
Drug exposure of human hepatocytes induces the expression of activating Natural killer (NK) cell ligands
We found that the expression of several ligands of NK cell receptors is influenced by drug exposure (Supplemental Table 1)

Summary

Introduction

Drug-induced liver injury (DILI) is one of the major challenges in drug development. (Godoy et al 2013). Natural killer (NK) cells are innate lymphocytes that are essential for providing immunity against viral infections and cancer They have the ability to detect transformed or infected cells and to induce apoptosis via the release of perforin- and granzymecontaining granules or via the engagement of death receptors such as Fas or TRAIL (Prager et al 2019). Known ligands for the activating NKp30 receptor include B7-H6 (Brandt et al 2009) and BAT3 (Pogge von Strandmann et al 2007) It is unknown whether the pretreatment of hepatocytes with compounds known to induce immunemediated DILI may influence the activity of NK cells. We show that ligands for the activating NK cell receptors NKp30 and NKG2D are upregulated on hepatocytes upon drug exposure This induces the activation of NK cells resulting in cellular cytotoxicity and the production of IFN-γ

Methods

Results

Discussion

Compliance with ethical standards