Understanding the pathogenesis of immune checkpoint inhibitor-induced hepatitis
File(s)
Author(s)
Gudd, Cathrin Luisa Carolin
Type
Thesis
Abstract
Background: Checkpoint inhibitors (CPIs) targeting cytotoxic T lymphocyte antigen- 4 (CTLA-4) and programmed cell death-1 (PD-1) are a novel class of cancer treatments, which stimulate anti-tumour immune responses. CPI treatment is frequently complicated by immune-related adverse events (irAE), including CPI- induced hepatitis (CPI-Hep), which represents one of the most common toxicities. This is a critical burden to treating malignancies, as CPI-related organ toxicities often require discontinuity of treatment and high-dose immunosuppression. This research aims to give insights into the underlying immunopathology of CPI-Hep and to highlight potential therapeutic pathways using both human samples and experimental models.
Methods: Flow cytometry and gene expression assays were used for in-depth characterisation of phenotype, functionality and transcriptional immune-profile of peripheral monocyte and T cells in patients with CPI-Hep. Intra-hepatic immune cells were assessed by immunohistochemistry. Using C57BL/6 wild-type mice, stimuli of hepatic inflammation [e.g. toll-like receptor ligands (TLR-L)] in combination with CPI treatment were trialled for the induction of experimental CPI-Hep. In vivo mechanistic investigations of CPI-Hep were carried out in Rag2-/- and Ccr2rfp/rfp transgenic mice.
Results: Human CPI-Hep is associated with an activated, tissue homing phenotype of peripheral CCR2highCCR7lowCD163high monocytes and HLA-DRhighICOShighTim- 3highCD8+ effector T cells with enhanced cytotoxicity. Liver biopsies mirrored the peripheral phenotype and revealed inflammatory clusters of CCR2+ macrophages with cytotoxic CD8+ T cells. In mice, co-administration of TLR9-L with CPIs mimicked human disease with mixed cytotoxic CD8+/CCR2+ monocyte/macrophage inflammatory aggregates and hepatocellular injury. In vivo investigation further revealed that CCR2+ monocytes are required for CD8+ T cell liver recruitment, while cytotoxic CD8+ T cells may play a role in mediating hepatocellular injury.
Conclusions: This work provides the first characterisation of the pathogenesis of CPI- Hep and identifies CCR2-driven monocyte recruitment to the liver as potential target for therapeutic intervention to treat liver inflammation in this condition.
Methods: Flow cytometry and gene expression assays were used for in-depth characterisation of phenotype, functionality and transcriptional immune-profile of peripheral monocyte and T cells in patients with CPI-Hep. Intra-hepatic immune cells were assessed by immunohistochemistry. Using C57BL/6 wild-type mice, stimuli of hepatic inflammation [e.g. toll-like receptor ligands (TLR-L)] in combination with CPI treatment were trialled for the induction of experimental CPI-Hep. In vivo mechanistic investigations of CPI-Hep were carried out in Rag2-/- and Ccr2rfp/rfp transgenic mice.
Results: Human CPI-Hep is associated with an activated, tissue homing phenotype of peripheral CCR2highCCR7lowCD163high monocytes and HLA-DRhighICOShighTim- 3highCD8+ effector T cells with enhanced cytotoxicity. Liver biopsies mirrored the peripheral phenotype and revealed inflammatory clusters of CCR2+ macrophages with cytotoxic CD8+ T cells. In mice, co-administration of TLR9-L with CPIs mimicked human disease with mixed cytotoxic CD8+/CCR2+ monocyte/macrophage inflammatory aggregates and hepatocellular injury. In vivo investigation further revealed that CCR2+ monocytes are required for CD8+ T cell liver recruitment, while cytotoxic CD8+ T cells may play a role in mediating hepatocellular injury.
Conclusions: This work provides the first characterisation of the pathogenesis of CPI- Hep and identifies CCR2-driven monocyte recruitment to the liver as potential target for therapeutic intervention to treat liver inflammation in this condition.
Version
Open Access
Date Issued
2020-07
Date Awarded
2020-12
Copyright Statement
Creative Commons Attribution NonCommercial Licence
License URL
Advisor
Possamai, Lucia
Khamri, Wafa
Woollard, Kevin
Goldin, Robert
Sponsor
The Royal Marsden Cancer Charity
Grant Number
A1783
Publisher Department
Department of Metabolism, Digestion and Reproduction
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)