title: GITR pathway activation abrogates tumor immune suppression through loss of regulatory T cell lineage stability.
abstract: Ligation of GITR (glucocorticoid-induced tumor necrosis factor (TNF) receptor-related gene, or TNFRSF18) by agonist antibody has recently entered into early phase clinical trials for the treatment of advanced malignancies. Although the ability of GITR modulation to induce tumor regression is well-documented in preclinical studies, the underlying mechanisms of action, particularly its effects on CD4(+)foxp3(+) regulatory T cells (Treg), have not been fully elucidated. We have previously demonstrated that GITR ligation in vivo by agonist antibody DTA-1 causes a >50% reduction of intra-tumor Treg with down modulation of Foxp3 expression. Here we show that the loss of Foxp3 is tumor-dependent. Adoptively-transferred Foxp3(+)Treg from tumor-bearing animals lose Foxp3 expression in the host when treated with DTA-1, whereas Treg from naïve mice maintain Foxp3 expression. GITR ligation also alters the expression of various transcription factors and cytokines important for Treg function. Complete Foxp3 loss in intra-tumor Treg correlates with a dramatic decrease in Helios expression and is associated with the upregulation of transcription factors T-Bet and Eomes. Changes in Helios correspond with a reduction in IL-10 and an increase in IFNγ expression in DTA-1-treated Treg. Together, these data show that GITR agonist antibody alters Treg lineage stability inducing an inflammatory effector T cell phenotype. The resultant loss of lineage stability causes Treg to lose their intra-tumor immune suppressive function, making the tumor susceptible to killing by tumor-specific effector CD8(+) T cells.
authors.affiliation: Swim Across America & Ludwig Collaborative Lab Laboratory, Immunology Program, Sloan-Kettering Institute for Cancer Research, Memorial Sloan-Kettering Cancer Center, New York, NY.
authors.forename: David A
authors.initials: DA
authors.lastname: Schaer
authors.affiliation: Swim Across America & Ludwig Collaborative Lab Laboratory, Immunology Program, Sloan-Kettering Institute for Cancer Research, Memorial Sloan-Kettering Cancer Center, New York, NY.
authors.forename: Sadna
authors.initials: S
authors.lastname: Budhu
authors.affiliation: Swim Across America & Ludwig Collaborative Lab Laboratory, Immunology Program, Sloan-Kettering Institute for Cancer Research, Memorial Sloan-Kettering Cancer Center, New York, NY.
authors.forename: Cailian
authors.initials: C
authors.lastname: Liu
authors.affiliation: Weill Cornell Medical College, Memorial Sloan-Kettering Cancer Center, New York, NY.
authors.forename: Campbell
authors.initials: C
authors.lastname: Bryson
authors.affiliation: Swim Across America & Ludwig Collaborative Lab Laboratory, Immunology Program, Sloan-Kettering Institute for Cancer Research, Memorial Sloan-Kettering Cancer Center, New York, NY ; Weill Cornell Medical College, Memorial Sloan-Kettering Cancer Center, New York, NY.
authors.forename: Nicole
authors.initials: N
authors.lastname: Malandro
authors.affiliation: Perelman Center for Advanced Medicine, University of Pennsylvania, Philadelphia, PA.
authors.forename: Adam
authors.initials: A
authors.lastname: Cohen
authors.affiliation: Swim Across America & Ludwig Collaborative Lab Laboratory, Immunology Program, Sloan-Kettering Institute for Cancer Research, Memorial Sloan-Kettering Cancer Center, New York, NY.
authors.forename: Hong
authors.initials: H
authors.lastname: Zhong
authors.affiliation: Swim Across America & Ludwig Collaborative Lab Laboratory, Immunology Program, Sloan-Kettering Institute for Cancer Research, Memorial Sloan-Kettering Cancer Center, New York, NY.
authors.forename: Xia
authors.initials: X
authors.lastname: Yang
authors.affiliation: Swim Across America & Ludwig Collaborative Lab Laboratory, Immunology Program, Sloan-Kettering Institute for Cancer Research, Memorial Sloan-Kettering Cancer Center, New York, NY.
authors.forename: Alan N
authors.initials: AN
authors.lastname: Houghton
authors.affiliation: Swim Across America & Ludwig Collaborative Lab Laboratory, Immunology Program, Sloan-Kettering Institute for Cancer Research, Memorial Sloan-Kettering Cancer Center, New York, NY.
authors.forename: Taha
authors.initials: T
authors.lastname: Merghoub
authors.affiliation: Swim Across America & Ludwig Collaborative Lab Laboratory, Immunology Program, Sloan-Kettering Institute for Cancer Research, Memorial Sloan-Kettering Cancer Center, New York, NY ; Weill Cornell Medical College, Memorial Sloan-Kettering Cancer Center, New York, NY ; Ludwig Center for Cancer Immunotherapy at Memorial Sloan-Kettering Cancer Center, New York, NY.
authors.forename: Jedd D
authors.initials: JD
authors.lastname: Wolchok
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D053450:Glucocorticoid-Induced TNFR-Related Protein / Q000819:agonists / Q000276:immunology* / Q000378:metabolism; D007108:Immune Tolerance; D008546:Melanoma, Experimental / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D050378:T-Lymphocytes, Regulatory / Q000276:immunology* / Q000378:metabolism
chemical_list: D053450:Glucocorticoid-Induced TNFR-Related Protein; C106544:Tnfrsf18 protein, mouse
keywords: Foxp3; GITR; Helios; Intra-tumor Immune suppression; Regulatory T cell Lineage Stability