Marro et al. prepared exhausted lymphocytic choriomeningitis virus (LCMV)-specific splenic CD8+ T cells that were deficient in IFNγ production following re-stimulation in vitro with LCMV peptides (but rescuable by anti-PDL-1), and utilized these cells in an antigen-dependent assay to screen a drug-repurposing library of 12,000 small molecules for reversal of T cell exhaustion, identifying Ingenol mebutate (IngMb), a diterpene ester targeting protein kinase C (PKC). IngMb induced IFNγ-producing CD8+ T cells that expressed markers of CD8+ T cell memory lineage and effector differentiation, supporting a role for PKC in reversing T cell exhaustion.
Contributed by Samuel Goldman
Inhibitory receptors (IRs) function as critical regulators of immune responses by tempering T cell activity. In humans, several persisting viruses as well as cancers exploit IR signaling by upregulating IR ligands, resulting in suppression of T cell function (i.e., exhaustion). This allows escape from immune surveillance and continuation of disease. Here, we report the design, implementation, and results of a phenotypic high-throughput screen for molecules that modulate CD8(+) T cell activity. We identify 19 compounds from the ReFRAME drug-repurposing collection that restore cytokine production and enhance the proliferation of exhausted T cells. Analysis of our top hit, ingenol mebutate, a protein kinase C (PKC) inducing diterpene ester, reveals a role for this molecule in overriding the suppressive signaling cascade mediated by IR signaling on T cells. Collectively, these results demonstrate a disease-relevant methodology for identifying modulators of T cell function and reveal new targets for immunotherapy.
Author Info: (1) Department of Immunology and Microbial Science, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA. (2) Department of Immunology and Microbi
Author Info: (1) Department of Immunology and Microbial Science, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA. (2) Department of Immunology and Microbial Science, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA. (3) Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA. (4) Department of Immunology and Microbial Science, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA. (5) Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA. (6) Department of Immunology and Microbial Science, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA. Electronic address: mbaobo@scripps.edu.
