title: PD-1 marks dysfunctional regulatory T cells in malignant gliomas.
abstract: Immunotherapies targeting the immune checkpoint receptor programmed cell death protein 1 (PD-1) have shown remarkable efficacy in treating cancer. CD4+CD25hiFoxP3+Tregs are critical regulators of immune responses in autoimmunity and malignancies, but the functional status of human Tregs expressing PD-1 remains unclear. We examined functional and molecular features of PD-1hiTregs in healthy subjects and patients with glioblastoma multiforme (GBM), combining functional assays, RNA sequencing, and cytometry by time of flight (CyTOF). In both patients with GBM and healthy subjects, circulating PD-1hiTregs displayed reduced suppression of CD4+effector T cells, production of IFN-γ, and molecular signatures of exhaustion. Transcriptional profiling of tumor-resident Tregs revealed that several genes coexpressed with PD-1 and associated with IFN-γ production and exhaustion as well as enrichment in exhaustion signatures compared with circulating PD-1hiTregs. CyTOF analysis of circulating and tumor-infiltrating Tregs from patients with GBM treated with PD-1-blocking antibodies revealed that treatment shifts the profile of circulating Tregs toward a more exhausted phenotype reminiscent of that of tumor-infiltrating Tregs, further increasing IFN-γ production. Thus, high PD-1 expression on human Tregs identifies dysfunctional, exhausted Tregs secreting IFN-γ that exist in healthy individuals and are enriched in tumor infiltrates, possibly losing function as they attempt to modulate the antitumoral immune responses.
authors.affiliation: Departments of Neurology and Immunobiology, Yale School of Medicine, New Haven, Connecticut, USA.
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Lowther
authors.affiliation: Departments of Biological Engineering and Chemical Engineering, Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
authors.forename: Brittany A
authors.initials: BA
authors.lastname: Goods
authors.affiliation: Departments of Neurology and Immunobiology, Yale School of Medicine, New Haven, Connecticut, USA.
authors.forename: Liliana E
authors.initials: LE
authors.lastname: Lucca
authors.affiliation: Departments of Neurology and Immunobiology, Yale School of Medicine, New Haven, Connecticut, USA.
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Lerner
authors.affiliation: Departments of Neurology and Immunobiology, Yale School of Medicine, New Haven, Connecticut, USA.
authors.forename: Khadir
authors.initials: K
authors.lastname: Raddassi
authors.affiliation: Department of Genetics, Yale School of Medicine, New Haven, Connecticut, USA.
authors.forename: David
authors.initials: D
authors.lastname: van Dijk
authors.affiliation: Departments of Neurology and Immunobiology, Yale School of Medicine, New Haven, Connecticut, USA.
authors.forename: Amanda L
authors.initials: AL
authors.lastname: Hernandez
authors.affiliation: Departments of Neurology and Immunobiology, Yale School of Medicine, New Haven, Connecticut, USA.
authors.forename: Xiangguo
authors.initials: X
authors.lastname: Duan
authors.affiliation: Department of Genetics, Yale School of Medicine, New Haven, Connecticut, USA; Department of Neurosurgery, Yale School of Medicine, New Haven, Connecticut, USA.
authors.forename: Murat
authors.initials: M
authors.lastname: Gunel
authors.affiliation: Bristol-Myers Squibb, Wallingford, Connecticut, USA.
authors.forename: Vlad
authors.initials: V
authors.lastname: Coric
authors.affiliation: Department of Genetics, Yale School of Medicine, New Haven, Connecticut, USA.
authors.forename: Smita
authors.initials: S
authors.lastname: Krishnaswamy
authors.affiliation: Departments of Biological Engineering and Chemical Engineering, Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA; Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA.
authors.forename: J Christopher
authors.initials: JC
authors.lastname: Love
authors.affiliation: Departments of Neurology and Immunobiology, Yale School of Medicine, New Haven, Connecticut, USA; Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Hafler