Targeting pathogenic CD8+ tissue-resident T cells with chimeric antigen receptor therapy in murine autoimmune cholangitis

Primary biliary cholangitis (PBC) is a cholestatic autoimmune liver disease characterized by autoreactive T cell response against intrahepatic small bile ducts. Here, we use Il12b -/- Il2ra -/- mice (DKO mice) as a model of autoimmune cholangitis and demonstrate that Cd8a knockout or treatment with an anti-CD8α antibody prevents/reduces biliary immunopathology. Using single-cell RNA sequencing analysis, we identified CD8 + tissue-resident memory T (Trm) cells in the livers of DKO mice, which highly express activation- and cytotoxicity-associated markers and induce apoptosis of bile duct epithelial cells. Liver CD8 + Trm cells also upregulate the expression of several immune checkpoint molecules, including PD-1. We describe the development of a chimeric antigen receptor to target PD-1-expressing CD8 + Trm cells. Treatment of DKO mice with PD-1-targeting CAR-T cells selectively depleted liver CD8 + Trm cells and alleviated autoimmune cholangitis. Our work highlights the pathogenic role of CD8 + Trm cells and the potential therapeutic usage of PD-1-targeting CAR-T cells. CD8 + T cells play an important role in primary biliary cholangitis (PBC). In this study, the authors demonstrate that PD-1-expressing CD8+ liver-resident T cells are pathogenic in murine PBC and that targeting these cells using a chimaeric antigen receptor reduces disease severity.