Damo and Fitzgerald et al. developed an ON/OFF system for inducible neoantigen expression (NINJA) featuring multiple regulators (Cre expression and doxycycline/tamoxifen administration) to avoid leaky antigen expression, which would activate central tolerance. When ON, NINJA-expressing tumors recruited neoantigen-specific T cells and slowed growth. In NINJA knock-in mice, neoantigen-specific T cells escaped tolerance and developed normally. Neoantigen expression could be spatially and temporally initiated to trigger tissue-specific endogenous T cell responses and pathology, or migration of transferred T cells.
Contributed by Alex Najibi
ABSTRACT: Inducible expression of neoantigens in mice would enable the study of endogenous antigen-specific nave T cell responses in disease and infection, but has been difficult to generate because leaky antigen expression in the thymus results in central T cell tolerance. Here we develop inversion-induced joined neoantigen (NINJA), using RNA splicing, DNA recombination and three levels of regulation to prevent leakiness and allow tight control over neoantigen expression. We apply NINJA to create tumor cell lines with inducible neoantigen expression, which could be used to study antitumor immunity. We also show that the genetic regulation in NINJA mice bypasses central and peripheral tolerance mechanisms and allows for robust endogenous CD8 and CD4 T cell responses on neoantigen induction in peripheral tissues. NINJA will enable studies of how T cells respond to defined neoantigens in the context of peripheral tolerance, transplantation, autoimmune diseases and cancer.