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 secondary to an autoreactive T cell response against intrahepatic small bile ducts. Multiple murine models have demonstrated the critical role of effector CD8+T cells in this response and our work has used IL-12p40-/-IL-2Rα-/- mice (DKO mice) to study this issue. Herein we first demonstrated that use of either a CD8a knock-out or an anti-CD8a antibody prevents/reduces biliary immunopathology. Bulk and single-cell RNA sequencing analysis identifies CD8+ tissue resident memory T cells (Trm) in the liver of DKO mice, which highly express activation and cytotoxicity associated markers and have the ability to induce apoptosis of bile duct epithelial cells. Liver CD8+Trm cells also upregulate expression of several immune checkpoint molecules and in particular we identified PD-1 as a specific liver CD8+Trm cell marker in this model. Based on these data we constructed a novel chimeric antigen receptor containing a PD-L1 extracellular domain to target PD-1-expressing CD8+Trm cells. Importantly, treatment of DKO mice with PD-1 targeting CAR-T cells selectively depleted liver CD8+Trm cells in vivo and alleviated autoimmune cholangitis. To access the efficacy of anti-PD-1 CAR-T treatment, we extracted the total RNA of liver tissues of DKO mice after anti-PD-1 CAR-T or Ctrl-T infusion and their control littermates, , then we build the cDNA library and performed the bulk RNA sequencing.