Zbtb20 Restrains CD8 T Cell Immunometabolism and Restricts Memory Differentiation and Antitumor Immunity.

CD8 T cell differentiation is orchestrated by dynamic metabolic changes that direct activation, proliferation, cytotoxic function, and epigenetic changes. We report that the BTB-ZF family transcriptional repressor Zbtb20 negatively regulates CD8 T cell metabolism and memory differentiation in mice. Effector and memory CD8 T cells with conditional Zbtb20 deficiency displayed enhanced mitochondrial and glycolytic metabolism, and memory CD8 T cells had enhanced spare respiratory capacity. Furthermore, Zbtb20-deficient CD8 T cells displayed increased flexibility in the use of mitochondrial fuel sources. Phenotypic and transcriptional skewing toward the memory fate was observed during the CD8 T cell response to Listeria monocytogenes Memory cells mounted larger secondary responses and conferred better protection following tumor challenge. These data suggest that inactivation of Zbtb20 may offer an approach to enhance metabolic activity and flexibility and improve memory CD8 T cell differentiation, useful attributes for T cells used in adoptive immunotherapy.

Dissociating STAT4 and STAT5 Signaling Inhibitory Functions of SOCS3: Effects on CD8 T Cell Responses.

Cytokines are critical for guiding the differentiation of T lymphocytes to perform specialized tasks in the immune response. Developing strategies to manipulate cytokine-signaling pathways holds promise to program T cell differentiation toward the most therapeutically useful direction. Suppressor of cytokine signaling (SOCS) proteins are attractive targets, as they effectively inhibit undesirable cytokine signaling. However, these proteins target multiple signaling pathways, some of which we may need to remain uninhibited. SOCS3 inhibits IL-12 signaling but also inhibits the IL-2-signaling pathway. In this study, we use computational protein design based on SOCS3 and JAK crystal structures to engineer a mutant SOCS3 with altered specificity. We generated a mutant SOCS3 designed to ablate interactions with JAK1 but maintain interactions with JAK2. We show that this mutant does indeed ablate JAK1 inhibition, although, unexpectedly, it still coimmunoprecipitates with JAK1 and does so to a greater extent than with JAK2. When expressed in CD8 T cells, mutant SOCS3 preserved inhibition of JAK2-dependent STAT4 phosphorylation following IL-12 treatment. However, inhibition of STAT phosphorylation was ablated following stimulation with JAK1-dependent cytokines IL-2, IFN-α, and IL-21. Wild-type SOCS3 inhibited CD8 T cell expansion in vivo and induced a memory precursor phenotype. In vivo T cell expansion was restored by expression of the mutant SOCS3, and this also reverted the phenotype toward effector T cell differentiation. These data show that SOCS proteins can be engineered to fine-tune their specificity, and this can exert important changes to T cell biology.