Saadey and Yousif et al. demonstrated that chronic TGFβ1 signaling epigenetically remodeled CD8+ T cells to accelerate and stabilize a terminally dysfunctional CD8+ T cell state upon persistent TCR stimulation. A Bone Morphogenetic Protein agonist (BMPa) limited the exhaustion features and enhanced survival of chronically stimulated CD8+ T cells. Simultaneously blocking TGFβ1 while potentiating BMP signaling rewired transcriptional circuits in terminally dysfunctional CD8+ T cells to restore effector function and memory programs. This enhanced tumor control in mice and boosted exhausted T cell responses to ICB therapy against lifelong chronic LCMV infection.
Contributed by Shishir Pant
ABSTRACT: T cell dysfunctionality prevents the clearance of chronic infections and cancer. Furthermore, epigenetic programming in dysfunctional CD8+ T cells limits their response to immunotherapies, including immune checkpoint blockade (ICB). However, it is unclear which upstream signals drive acquisition of dysfunctional epigenetic programs, and whether therapeutically targeting these signals can remodel terminally dysfunctional T cells to an ICB-responsive state. Here we innovate an in vitro model system of stable human T cell dysfunction and show that chronic TGFβ1 signaling in posteffector CD8+ T cells accelerates their terminal dysfunction through stable epigenetic changes. Conversely, boosting bone morphogenetic protein (BMP) signaling while blocking TGFβ1 preserved effector and memory programs in chronically stimulated human CD8+ T cells, inducing superior responses to tumors and synergizing the ICB responses during chronic viral infection. Thus, rebalancing TGFβ1/BMP signals provides an exciting new approach to unleash dysfunctional CD8+ T cells and enhance T cell immunotherapies.