Misc

© 2019, The Author(s), under exclusive licence to Springer Nature Limited. T cells expressing chimeric antigen receptors (CAR T cells) targeting human CD19 (hCD19) have shown clinical efficacy against B cell malignancies 1,2 . CAR T cells have been less effective against solid tumours 3–5 , in part because they enter a hyporesponsive (‘exhausted’ or ‘dysfunctional’) state 6–9 triggered by chronic antigen stimulation and characterized by upregulation of inhibitory receptors and loss of effector function. To investigate the function of CAR T cells in solid tumours, we transferred hCD19-reactive CAR T cells into hCD19 + tumour-bearing mice. CD8 + CAR + tumour-infiltrating lymphocytes and CD8 + endogenous tumour-infiltrating lymphocytes expressing the inhibitory receptors PD-1 and TIM3 exhibited similar profiles of gene expression and chromatin accessibility, associated with secondary activation of nuclear receptor transcription factors NR4A1 (also known as NUR77), NR4A2 (NURR1) and NR4A3 (NOR1) by the initiating transcription factor NFAT (nuclear factor of activated T cells) 10–12 . CD8 + T cells from humans with cancer or chronic viral infections 13–15 expressed high levels of NR4A transcription factors and displayed enrichment of NR4A-binding motifs in accessible chromatin regions. CAR T cells lacking all three NR4A transcription factors (Nr4a triple knockout) promoted tumour regression and prolonged the survival of tumour-bearing mice. Nr4a triple knockout CAR tumour-infiltrating lymphocytes displayed phenotypes and gene expression profiles characteristic of CD8 + effector T cells, and chromatin regions uniquely accessible in Nr4a triple knockout CAR tumour-infiltrating lymphocytes compared to wild type were enriched for binding motifs for NF-κB and AP-1, transcription factors involved in activation of T cells. We identify NR4A transcription factors as having an important role in the cell-intrinsic program of T cell hyporesponsiveness and point to NR4A inhibition as a promising strategy for cancer immunotherapy.

© 2019, Springer Nature Limited. In addition to maintaining immune tolerance, FOXP3 + regulatory T (T reg ) cells perform specialized functions in tissue homeostasis and remodelling 1,2 . However, the characteristics and functions of brain T reg cells are not well understood because there is a low number of T reg cells in the brain under normal conditions. Here we show that there is massive accumulation of T reg cells in the mouse brain after ischaemic stroke, and this potentiates neurological recovery during the chronic phase of ischaemic brain injury. Although brain T reg cells are similar to T reg cells in other tissues such as visceral adipose tissue and muscle 3–5 , they are apparently distinct and express unique genes related to the nervous system including Htr7, which encodes the serotonin receptor 5-HT 7 . The amplification of brain T reg cells is dependent on interleukin (IL)-2, IL-33, serotonin and T cell receptor recognition, and infiltration into the brain is driven by the chemokines CCL1 and CCL20. Brain T reg cells suppress neurotoxic astrogliosis by producing amphiregulin, a low-affinity epidermal growth factor receptor (EGFR) ligand. Stroke is a leading cause of neurological disability, and there are currently few effective recovery methods other than rehabilitation during the chronic phase. Our findings suggest that T reg cells and their products may provide therapeutic opportunities for neuronal protection against stroke and neuroinflammatory diseases.