Adoptive cell therapy represents a new paradigm in cancer immunotherapy but can be limited by poor persistence and function of transferred T cells 1. Here, through an in vivo pooled CRISPR-Cas9 mutagenesis screening, we demonstrate that CD8 + T cells are reprogrammed to long-lived effector cells with extensive accumulation, better persistence and robust effector function in tumors by targeting Regnase-1. Regnase-1-deficient CD8 + T cells show markedly improved therapeutic efficacy against mouse melanoma and leukemia. Through a secondary genome-scale CRISPR-Cas9 screening, we identify BATF as the key target of Regnase-1 and a rheostat in shaping antitumor responses. Loss of BATF suppresses the elevated accumulation and mitochondrial fitness of Regnase-1-deficient CD8 + T cells. Conversely, we reveal that targeting additional signaling factors including PTPN2 and SOCS1 improves the therapeutic efficacy of Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:

Regulatory T (T reg ) cells are essential for immune tolerance 1 but also drive immunosuppression in the tumour microenvironment (TME) 2 . Therapeutic targeting of T reg cells in cancer requires the identification of context-specific mechanisms for T reg cell function. Here we demonstrate that inhibition of sterol regulatory element-binding protein (SREBP)-dependent lipid synthesis and metabolic signalling in T reg cells unleashes effective antitumour immune responses without autoimmune toxicity. SREBP activity is upregulated in intratumoural T reg cells, and T reg cell-specific deletion of SCAP, an obligatory factor for SREBP activity, inhibits tumour growth and boosts anti-PD-1 immunotherapy, associated with uncontrolled IFN-γ production and impaired function of intratumoural T reg cells. Mechanistically, SCAP/SREBP signalling coordinates lipid synthetic programs and inhibitory receptor signalling in T reg cells. First, de novo fatty acid synthesis mediated by fatty acid synthase (FASN) contributes to functional maturation of T reg cells, and loss of FASN in T reg cells inhibits tumour growth. Second, T reg cells show enhanced Pdcd1 expression in tumours in a process dependent on SREBP activity that further signals to mevalonate metabolism-driven protein geranylgeranylation, and blocking PD-1 or SREBP signaling results in dysregulated PI3K activation in intratumoural T reg cells. Our findings establish that metabolic reprogramming enforces T reg cell functional specialization in tumours, pointing to new avenues to target T reg cells for cancer therapy.

Regulatory T (Treg) cells derived from the thymus (tTreg) and periphery (pTreg) have central and distinct functions in immunosuppression, but mechanisms for the generation and activation of Treg subsets in vivo are unclear. Here, we show that mechanistic target of rapamycin (mTOR) unexpectedly supports the homeostasis and functional activation of tTreg and pTreg cells. mTOR signaling is crucial for programming activated Treg-cell function to protect immune tolerance and tissue homeostasis. Treg-specific deletion of mTOR drives spontaneous effector T-cell activation and inflammation in barrier tissues and is associated with reduction in both thymic-derived effector Treg (eTreg) and pTreg cells. Mechanistically, mTOR functions downstream of antigenic signals to drive IRF4 expression and mitochondrial metabolism, and accordingly, deletion of mitochondrial transcription factor A (Tfam) severely impairs Treg-cell suppressive function and eTreg-cell generation. Collectively, our results show that mTOR coordinates transcriptional and metabolic programs in activated Treg subsets to mediate tissue homeostasis.

A defining feature of adaptive immunity is the development of long-lived memory T cells to curtail infection. Recent studies have identified a unique stem-like T cell subset in exhausted CD8+ T cells in chronic infection1–3, but it remains unclear whether CD4+ T cell subsets with similar features exist in chronic inflammatory conditions. Among helper T cells, TH17 cells play prominent roles in autoimmunity and tissue inflammation and are characterized by inherent plasticity4–7, although the regulation of plasticity is poorly understood. Here we demonstrate that TH17 cells in autoimmune disease are functionally and metabolically heterogeneous and contain a subset with stemness-associated features but lower anabolic metabolism, and a reciprocal subset with higher metabolic activity that supports the transdifferentiation into TH1 cells. These two TH17 cell subsets are defined by selective expression of transcription factors TCF-1 and T-bet, and discrete CD27 expression levels. Moreover, we identify mTORC1 signaling as a central regulator to orchestrate TH17 cell fates by coordinating metabolic and transcriptional programs. TH17 cells with disrupted mTORC1 or anabolic metabolism fail to induce autoimmune neuroinflammation or develop into TH1-like cells, but instead upregulate TCF-1 expression and activity and acquire stemness-associated features. Single cell RNA-sequencing and experimental validation reveal heterogeneity in fate-mapped TH17 cells, and a developmental arrest in the TH1 transdifferentiation trajectory upon mTORC1 deletion or metabolic perturbation. Our results establish that the dichotomy of stemness and effector function underlies the heterogeneous TH17 responses and autoimmune pathogenesis, and point to previously unappreciated metabolic control of helper T cell plasticity.

Dendritic cells (DCs) orchestrate the crosstalk between innate and adaptive immunity. CD8α+ DCs present antigens to CD8+ T cells and elicit cytotoxic T-cell responses to viruses, bacteria and tumors1. Although lineage-specific transcriptional regulators of CD8α+ DC development have been identified2, the molecular pathways that selectively orchestrate CD8α+ DC function remain elusive. Moreover, metabolic reprogramming is important for DC development and activation3,4, but metabolic dependence and regulation of DC subsets are unknown. Here, we describe a data-driven systems biology algorithm (NetBID) and an unexpected role of Hippo pathway kinases, Mst1 and Mst2 (Mst1/2), in selectively programming CD8α+ DC function and metabolism. Our NetBID analysis reveals a marked enrichment of the activities of Hippo pathway kinases in CD8α+ DCs relative to CD8α− DCs. DC-specific deletion of Mst1/2, but not Lats1/2 or Yap/Taz that mediate canonical Hippo signaling, disrupts homeostasis and function of CD8+ T cells and anti-tumor immunity. Mst1/2-deficient CD8α+ DCs are impaired in presenting extracellular proteins and cognate peptides to prime CD8+ T cells, while CD8α− DCs lacking Mst1/2 have largely normal function. Mechanistically, compared with CD8α− DCs, CD8α+ DCs show much stronger oxidative metabolism and critically depend upon Mst1/2 signaling to maintain bioenergetic activities and mitochondrial dynamics for functional capacities. Further, CD8α+ DCs selectively express IL-12 that depends upon Mst1/2 and the crosstalk with non-canonical NF-κB signaling. Our findings identify Mst1/2 as selective drivers of CD8α+ DC function by integrating metabolic activity and cytokine signaling, and highlight that the interplay between immune signaling and metabolic reprogramming underlies the unique function of DC subsets.