Background & aims: Virus-specific T cell dysfunction is a common feature of HBV-related hepatocellular carcinoma (HBV-HCC). Conventional T (ConT) cells can be redirected towards viral antigens in HBV-HCC when they express an HBV-specific receptor; however, their efficacy can be impaired by liver-specific physical and metabolic features. Mucosal-associated invariant T (MAIT) cells are the most abundant innate-like T cells in the liver and can elicit potent intrahepatic effector functions. Here, we engineered ConT and MAIT cells to kill HBV expressing hepatoma cells and compared their functional properties.
Methods: Donor-matched ConT and MAIT cells were engineered to express an HBV-specific T cell receptor (TCR). Cytotoxicity and hepatocyte homing potential were investigated using flow cytometry, real-time killing assays, and confocal microscopy in 2D and 3D HBV-HCC cell models. Major histocompatibility complex (MHC) class I-related molecule (MR1)-dependent and MR1-independent activation was evaluated in an Escherichia coli THP-1 cell model and by IL-12/IL-18 stimulation, respectively.
Results: HBV TCR-MAIT cells demonstrated polyfunctional properties (CD107a, interferon [IFN] γ, tumour necrosis factor [TNF], and IL-17A) with strong HBV target sensitivity and liver-homing chemokine receptor expression when compared with HBV TCR-ConT cells. TCR-mediated lysis of hepatoma cells was comparable between the cell types and augmented in the presence of inflammation. Coculturing with HBV+ target cells in a 3D microdevice mimicking aspects of the liver microenvironment demonstrated that TCR-MAIT cells migrate readily towards hepatoma targets. Expression of an ectopic TCR did not affect the ability of the MAIT cells to be activated via MR1-presented bacterial antigens or IL-12/IL-18 stimulation.
Conclusions: HBV TCR-MAIT cells demonstrate anti-HBV functions without losing their endogenous antimicrobial mechanisms or hepatotropic features. Our results support future exploitations of MAIT cells for liver-directed immunotherapies.
Lay summary: Chronic HBV infection is a leading cause of liver cancer. T cell receptor (TCR)-engineered T cells are patients' immune cells that have been modified to recognise virus-infected and/or cancer cells. Herein, we evaluated whether mucosal-associated invariant T cells, a large population of unconventional T cells in the liver, could recognise and kill HBV infected hepatocytes when engineered with an HBV-specific TCR. We show that their effector functions may exceed those of conventional T cells currently used in the clinic, including antimicrobial properties and chemokine receptor profiles better suited for targeting liver tumours.
Keywords: 5-OP-RU, 5-(2-oxopropylideneamino)-6-d-ribitylaminouracil; APC, allophycocyanin; Adoptive cell transfer; CAR, chimeric antigen receptor; CCR, CC chemokine receptor; CXCL, chemokine (CXC) ligand; CXCR, CXC chemokine receptor; ConT, conventional T; DCI, dead cell index; FMO, fluorescence minus one; FSC, forward scatter; HBV; HCC; HCC, hepatocellular carcinoma; HLA, human leukocyte antigen; IFN, interferon; IR, irrelevant peptide; MAIT cells; MAIT, mucosal-associated invariant T; MFI, mean fluorescence intensity; MHC, major histocompatibility complex; MR1, MHC class I-related molecule; PBMC, peripheral blood mononuclear cell; PE, phycoerythrin; PMA, phorbol myristate acetate; RT, room temperature; SSC, side scatter; TCR, T cell receptor; TCR-T cells; TNF, tumour necrosis function; UMAP, Uniform Manifold Approximation and Projection; VCAM-1, vascular cell adhesion molecule-1; VLA-4, very late antigen-4.
© 2021 The Authors.