No abstract

Oxygenation levels are a determinative factor in T cell function. Here we describe that the oxygen tensions sensed by mouse and human T cells at the moment of activation act to persistently modulate both differentiation and function. We found that in a protocol of CAR-T cell generation, 24 hours of low oxygen levels during initial CD8+ T cell priming is sufficient to enhance antitumour cytotoxicity in a preclinical model. This is the case even when CAR-T cells are subsequently cultured under high oxygen tensions prior to adoptive transfer. Increased hypoxia inducible transcription factor (HIF) expression was able to alter T cell fate in a similar manner to exposure to low oxygen tensions; however, only a controlled or temporary increase in HIF signalling was able to consistently improve cytotoxic function of T cells. These data show that oxygenation levels during and immediately after T cell activation play an essential role in regulating T cell function.

T cell function is influenced by several metabolites; some acting through enzymatic inhibition of α-KG-dependent dioxygenases (αKGDDs), others, through post-translational modification of lysines in important targets. We show here that glutarate, a product of amino acid catabolism, has the capacity to do both, with effects on T cell function and differentiation. Glutarate exerts those effects through αKGDD inhibition and through direct regulation of T cell metabolism via post-translational modification of the pyruvate dehydrogenase E2 subunit. Diethyl-glutarate, a cell-permeable form of glutarate, alters CD8+T cell differentiation and increases cytotoxicity against target cells.In vivoadministration of the compound reduces tumor growth and is correlated with increased levels of both peripheral and intratumoral cytotoxic CD8+T cells. These results demonstrate that glutarate regulates both T cell metabolism and differentiation, with a potential role in the improvement of T cell immunotherapy.

SummaryOxygenation levels are a determinative factor in T cell function. Here we describe that the oxygen tensions sensed by T cells at the moment of activation act to persistently modulate both differentiation and function. We found that in a protocol of CAR-T cell generation, 24 hours of low oxygen levels during initial CD8+T cell priming is sufficient to enhance antitumour cytotoxicity in a preclinical model. This is the case even when CAR-T cells are subsequently cultured under high oxygen tensions prior to adoptive transfer. Increased hypoxia inducible transcription factor (HIF) expression was able to alter T cell fate in a similar manner to exposure to low oxygen tensions; however, only a controlled or temporary increase in HIF signalling was able to consistently improve cytotoxic function of T cells. These data show that oxygenation levels during and immediately after T cell activation play an essential role in regulating T cell function.

Nitric oxide (NO) is a signaling molecule produced by NO synthases (NOS1-3) to control processes such as neurotransmission, vascular permeability, and immune function. Although myeloid cell-derived NO has been shown to suppress T-cell responses, the role of NO synthesis in T cells themselves is not well understood. Here, we showed that significant amounts of NO were synthesized in human and murine CD8+ T cells following activation. Tumor growth was significantly accelerated in a T cell-specific, Nos2-null mouse model. Genetic deletion of Nos2 expression in murine T cells altered effector differentiation, reduced tumor infiltration, and inhibited recall responses and adoptive cell transfer function. These data show that endogenous NO production plays a critical role in T cell-mediated tumor immunity.