Costimulation Endows Immunotherapeutic CD8 T Cells with IL-36 Responsiveness during Aerobic Glycolysis

Abstract

CD134 and CD137 primed CD8 T cells mount powerful effector responses upon recall, but even without recall these dual costimulated T cells respond to signal 3 cytokines like IL-12. We searched for alternative signal 3 receptor pathways and found the IL-1 family member IL-36R. While IL-36 alone did not stimulate effector CD8 T cells, in combination with IL-12, or more surprisingly IL-2, induced striking and rapid TCR-independent IFN-γ synthesis. To understand how signal 3 responses functioned in dual costimulated T cells we showed that IL-2 induced IL-36R gene expression in a JAK/STAT dependent manner. These data help delineate a sequential stimulation process where IL-2 conditioning must precede IL-36 for IFN-γ synthesis. Importantly, this responsive state was transient, and functioned only in effector T cells capable of aerobic glycolysis. Specifically, as the effector T cells metabolized glucose and consumed O2, they also retained potential to respond through IL-36R. This suggests that T cells use innate receptor pathways like the IL-36R-axis when programmed for aerobic glycolysis. To explore a function for IL-36R in vivo we showed that dual costimulation therapy reduced B16 melanoma tumor growth while increasing IL-36R gene expression. In sum, cytokine therapy to eliminate tumors may target effector T cells, even outside of TCR specificity, as long as the effectors are in the correct metabolic state.

Cytokines and metabolic factors regulate tumoricidal T-cell function during cancer immunotherapy

“…A notable attribute of dual costimulated CD8 T cells in this regard is their ability to be triggered by cytokines in the absence of TCR stimulation. Specifically, stimulation with either IL-12 or IL-2 followed by either of the IL-1 family members IL-33 or IL-36 induces IFN-γ secretion, subsequent induction of MHC class I and II on tumor cells, and degranulation of the CD8 + CTL [134,135]. The underlying mechanism of this TCR-independent process was further studied with the IL-2 plus IL-36 combination, where it was found that IL-2 activates the JAK-STAT pathway that induces transcription of the Il1rl2 gene that encodes the IL-36 receptor [135].…”

“…Specifically, stimulation with either IL-12 or IL-2 followed by either of the IL-1 family members IL-33 or IL-36 induces IFN-γ secretion, subsequent induction of MHC class I and II on tumor cells, and degranulation of the CD8 + CTL [134,135]. The underlying mechanism of this TCR-independent process was further studied with the IL-2 plus IL-36 combination, where it was found that IL-2 activates the JAK-STAT pathway that induces transcription of the Il1rl2 gene that encodes the IL-36 receptor [135]. CD8 + CTL must actively undergo aerobic glycolysis to secrete IFN-γ because GAPDH binds to the IFN-γ mRNA 3′UTR to block translation when it is not catalyzing glycolysis [54].…”

“…CD8 + CTL must actively undergo aerobic glycolysis to secrete IFN-γ because GAPDH binds to the IFN-γ mRNA 3′UTR to block translation when it is not catalyzing glycolysis [54]. Correspondingly, the ability of dual costimulated CD8 T cells to be triggered by cytokines to secrete IFN-γ tracks with their glycolytic potential that is robust at the early effector stage but later diminishes as they begin transitioning into memory cells [135]. This is critical since TIL must compete with glycolytic tumor cells for limited supplies of glucose [52,53].…”

“…This is critical since TIL must compete with glycolytic tumor cells for limited supplies of glucose [52,53]. Importantly, dual costimulated CD8 + effectors appear to be worthy competitors due to their robust expression of the glucose transporter Glut1 [135].…”

“…IL-33 may play a particularly important role during dual costimulation since it cross-regulates immunity, obesity and cancer [141], and as we propose in In addition to releasing the brakes on tumor-specific T cells [62], PD-1/PD-L1 checkpoint therapy decreases tumor cell glycolysis and glucose consumption, thus increasing glucose availability to tumor infiltrating lymphocyte (TIL) and enabling them to fuel aerobic glycolysis and secrete IFN-γ [52][53][54]67]. (C) Based on their robust glycolytic potential and expression of the glucose transporter Glut1 [135], dual costimulated CD8 T cells should be competitive in the tumor microenvironment. (D) We propose that PD-1/PD-L1 blockade and dual costimulation will be therapeutically synergistic because they confer distinct, complimentary metabolic advantages to the CD8 + TIL.…”