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CD8+ cytotoxic T cells (CTLs) orchestrate antitumour immunity and exhibit inherent heterogeneity1,2, with precursor exhausted T (Tpex) cells but not terminally exhausted T (Tex) cells capable of responding to existing immunotherapies3–7. The gene regulatory network that underlies CTL differentiation and whether Tex cell responses can be functionally reinvigorated are incompletely understood. Here we systematically mapped causal gene regulatory networks using single-cell CRISPR screens in vivo and discovered checkpoints for CTL differentiation. First, the exit from quiescence of Tpex cells initiated successive differentiation into intermediate Tex cells. This process is differentially regulated by IKAROS and ETS1, the deficiencies of which dampened and increased mTORC1-associated metabolic activities, respectively. IKAROS-deficient cells accumulated as a metabolically quiescent Tpex cell population with limited differentiation potential following immune checkpoint blockade (ICB). Conversely, targeting ETS1 improved antitumour immunity and ICB efficacy by boosting differentiation of Tpex to intermediate Tex cells and metabolic rewiring. Mechanistically, TCF-1 and BATF are the targets for IKAROS and ETS1, respectively. Second, the RBPJ–IRF1 axis promoted differentiation of intermediate Tex to terminal Tex cells. Accordingly, targeting RBPJ enhanced functional and epigenetic reprogramming of Tex cells towards the proliferative state and improved therapeutic effects and ICB efficacy. Collectively, our study reveals that promoting the exit from quiescence of Tpex cells and enriching the proliferative Tex cell state act as key modalities for antitumour effects and provides a systemic framework to integrate cell fate regulomes and reprogrammable functional determinants for cancer immunity.Analyses of causal gene regulatory networks have identified key checkpoints mediating the progressive differentiation of CD8+ cytotoxic T cells, findings that have implications for anticancer immunotherapies such as adoptive cell therapy and immune checkpoint blockade. [ABSTRACT FROM AUTHOR]

Cancer cells evade T cell-mediated killing through tumour–immune interactions whose mechanisms are not well understood1,2. Dendritic cells (DCs), especially type-1 conventional DCs (cDC1s), mediate T cell priming and therapeutic efficacy against tumours3. DC functions are orchestrated by pattern recognition receptors3–5, although other signals involved remain incompletely defined. Nutrients are emerging mediators of adaptive immunity6–8, but whether nutrients affect DC function or communication between innate and adaptive immune cells is largely unresolved. Here we establish glutamine as an intercellular metabolic checkpoint that dictates tumour–cDC1 crosstalk and licenses cDC1 function in activating cytotoxic T cells. Intratumoral glutamine supplementation inhibits tumour growth by augmenting cDC1-mediated CD8+ T cell immunity, and overcomes therapeutic resistance to checkpoint blockade and T cell-mediated immunotherapies. Mechanistically, tumour cells and cDC1s compete for glutamine uptake via the transporter SLC38A2 to tune anti-tumour immunity. Nutrient screening and integrative analyses show that glutamine is the dominant amino acid in promoting cDC1 function. Further, glutamine signalling via FLCN impinges on TFEB function. Loss of FLCN in DCs selectively impairs cDC1 function in vivo in a TFEB-dependent manner and phenocopies SLC38A2 deficiency by eliminating the anti-tumour therapeutic effect of glutamine supplementation. Our findings establish glutamine-mediated intercellular metabolic crosstalk between tumour cells and cDC1s that underpins tumour immune evasion, and reveal glutamine acquisition and signalling in cDC1s as limiting events for DC activation and putative targets for cancer treatment.Competition for glutamine between type-1 conventional dendritic cells and tumour cells has a central role in tuning the anti-tumour immune response and in immune evasion by cancer cells. [ABSTRACT FROM AUTHOR]

Summary: Dendritic cells (DCs) are innate immune cells that detect and process environmental signals and communicate them with T cells to bridge innate and adaptive immunity. Immune signals and microenvironmental cues shape the function of DC subsets in different contexts, which is associated with reprogramming of cellular metabolic pathways. In addition to integrating these extracellular cues to meet bioenergetic and biosynthetic demands, cellular metabolism interplays with immune signaling to shape DC‐dependent immune responses. Emerging evidence indicates that lipid metabolism serves as a key regulator of DC responses. Here, we summarize the roles of fatty acid and cholesterol metabolism, as well as selective metabolites, in orchestrating the functions of DCs. Specifically, we highlight how different lipid metabolic programs, including de novo fatty acid synthesis, fatty acid β oxidation, lipid storage, and cholesterol efflux, influence DC function in different contexts. Further, we discuss how dysregulation of lipid metabolism shapes DC intracellular signaling and contributes to the impaired DC function in the tumor microenvironment. Finally, we conclude with a discussion on key future directions for the regulation of DC biology by lipid metabolism. Insights into the connections between lipid metabolism and DC functional specialization may facilitate the development of new therapeutic strategies for human diseases. [ABSTRACT FROM AUTHOR]

Many signaling and other genes known as “hidden” drivers may not be genetically or epigenetically altered or differentially expressed at the mRNA or protein levels, but, rather, drive a phenotype such as tumorigenesis via post-translational modification or other mechanisms. However, conventional approaches based on genomics or differential expression are limited in exposing such hidden drivers. Here, we present a comprehensive algorithm and toolkit NetBID2 (data-driven network-based Bayesian inference of drivers, version 2), which reverse-engineers context-specific interactomes and integrates network activity inferred from large-scale multi-omics data, empowering the identification of hidden drivers that could not be detected by traditional analyses. NetBID2 has substantially re-engineered the previous prototype version by providing versatile data visualization and sophisticated statistical analyses, which strongly facilitate researchers for result interpretation through end-to-end multi-omics data analysis. We demonstrate the power of NetBID2 using three hidden driver examples. We deploy NetBID2 Viewer, Runner, and Cloud apps with 145 context-specific gene regulatory and signaling networks across normal tissues and paediatric and adult cancers to facilitate end-to-end analysis, real-time interactive visualization and cloud-based data sharing. NetBID2 is freely available at .It’s challenging to capture “hidden” drivers that may not be genetically-altered or differentially-expressed from omics data. Here the authors developed NetBID2, a comprehensive network-based toolbox with versatile features, enabling the integration of multi-omics data to expose such hidden drivers. [ABSTRACT FROM AUTHOR]

Purpose: Information about dynamic changes occurring in the parameters and morphology of erythrocytes and platelets during the coronavirus disease 2019 (COVID-19) infection and convalescence is scarce. To explore potential associations between dynamic erythrocyte and platelet parameters, morphological changes, and the course or severity of the disease is essential. Patients and Methods: From January 17th, 2020, to February 20th, 2022, we followed up on 35 patients with non-severe and 11 patients with severe COVID-19 following their discharge. We collected clinical features, dynamic complete blood count (CBC), and peripheral blood smears (PBS) and analyzed parameter and morphological changes of erythrocytes and platelets depending on the course or severity of the disease. The course of the disease included four periods, namely onset (T1), discharge (T2), 1-year follow-up (T3), and 2-year follow-up (T4). Results: Red blood cell (RBC) counts and hemoglobin were the lowest in T2, followed by T1, and lower in T1 and T2 than in T3 and T4. Inversely, the red blood cell distribution width (RDW) was the highest in T2, followed by T1, and higher than in T3 and T4. Compared to non-severe patients, the platelet of severe patients was lower in T1 and T2. In contrast, the mean platelet volume (MPV) and platelet distribution width (PDW) tended to be higher in severe patients. Similarly, anisocytosis was more common in peripheral blood smears at early stages and in severe patients. Finally, large platelets were more common in severe patients. Conclusion: Anisocytosis of erythrocytes and large platelets are found in patients with severe COVID-19, these changes may help primary hospitals to identify patients with a high risk of severe COVID-19 at an early stage. [ABSTRACT FROM AUTHOR]

The article explores Thalassemia is an inherited blood disease characterized by an imbalanced synthesis of hemoglobin (Hb) chains, leading to phenotypes ranging from severe anemia to clinically asymptomatic. Thalassemia heterozygotes who harbor one normal β-globin gene (HBB) generally exhibit features of microcytic and hypochromic anemia.

Aims A hallmark of advanced atherosclerosis is inadequate immunosuppression by regulatory T (Treg) cells inside atherosclerotic lesions. Dyslipidemia has been suggested to alter Treg cell migration by affecting the expression of specific membrane proteins, thereby decreasing Treg cell migration towards atherosclerotic lesions. Besides membrane proteins, cellular metabolism has been shown to be a crucial factor in Treg cell migration. We aimed to determine whether dyslipidemia contributes to altered migration of Treg cells, in part, by affecting cellular metabolism. Methods and results Dyslipidemia was induced by feeding Ldlr −/− mice a western-type diet for 16–20 weeks and intrinsic changes in Treg cells affecting their migration and metabolism were examined. Dyslipidemia was associated with altered mTORC2 signalling in Treg cells, decreased expression of membrane proteins involved in migration, including CD62L, CCR7, and S1Pr1, and decreased Treg cell migration towards lymph nodes. Furthermore, we discovered that diet-induced dyslipidemia inhibited mTORC1 signalling, induced PPARδ activation and increased fatty acid (FA) oxidation in Treg cells. Moreover, mass-spectrometry analysis of serum from Ldlr −/− mice with normolipidemia or dyslipidemia showed increases in multiple PPARδ ligands during dyslipidemia. Treatment with a synthetic PPARδ agonist increased the migratory capacity of Treg cells in vitro and in vivo in an FA oxidation-dependent manner. Furthermore, diet-induced dyslipidemia actually enhanced Treg cell migration into the inflamed peritoneum and into atherosclerotic lesions in vitro. Conclusion Altogether, our findings implicate that dyslipidemia does not contribute to atherosclerosis by impairing Treg cell migration as dyslipidemia associated with an effector-like migratory phenotype in Treg cells. [ABSTRACT FROM AUTHOR]

Regulatory T cells (Treg cells) are essential for immune tolerance1, but also drive immunosuppression in the tumour microenvironment2. Therapeutic targeting of Treg cells in cancer will therefore require the identification of context-specific mechanisms that affect their function. Here we show that inhibiting lipid synthesis and metabolic signalling that are dependent on sterol-regulatory-element-binding proteins (SREBPs) in Treg cells unleashes effective antitumour immune responses without autoimmune toxicity. We find that the activity of SREBPs is upregulated in intratumoral Treg cells. Moreover, deletion of SREBP-cleavage-activating protein (SCAP)—a factor required for SREBP activity—in these cells inhibits tumour growth and boosts immunotherapy that is triggered by targeting the immune-checkpoint protein PD-1. These effects of SCAP deletion are associated with uncontrolled production of interferon-γ and impaired function of intratumoral Treg cells. Mechanistically, signalling through SCAP and SREBPs coordinates cellular programs for lipid synthesis and inhibitory receptor signalling in these cells. First, de novo fatty-acid synthesis mediated by fatty-acid synthase (FASN) contributes to functional maturation of Treg cells, and loss of FASN from Treg cells inhibits tumour growth. Second, Treg cells in tumours show enhanced expression of the PD-1 gene, through a process that depends on SREBP activity and signals via mevalonate metabolism to protein geranylgeranylation. Blocking PD-1 or SREBP signalling results in dysregulated activation of phosphatidylinositol-3-kinase in intratumoral Treg cells. Our findings show that metabolic reprogramming enforces the functional specialization of Treg cells in tumours, pointing to new ways of targeting these cells for cancer therapy.Identification of a metabolic checkpoint involving lipid signalling that is specific to regulatory T cells (Treg cells) in the tumour microenvironment raises the possibility of targeting this checkpoint for treatment of cancer. [ABSTRACT FROM AUTHOR]

Objectives: In December 2019, there was an outbreak of coronavirus disease 2019 (COVID-19) in Wuhan, China, and since then, the disease has been increasingly spread throughout the world. Unfortunately, the information about early prediction factors for disease progression is relatively limited. Therefore, there is an urgent need to investigate the risk factors of developing severe disease. The objective of the study was to reveal the risk factors of developing severe disease by comparing the differences in the hemocyte count and dynamic profiles in patients with severe and non-severe COVID-19. Methods: In this retrospectively analyzed cohort, 141 confirmed COVID-19 patients were enrolled in Taizhou Public Health Medical Center, Taizhou Hospital, Zhejiang Province, China, from January 17, 2020 to February 26, 2020. Clinical characteristics and hemocyte counts of severe and non-severe COVID patients were collected. The differences in the hemocyte counts and dynamic profiles in patients with severe and non-severe COVID-19 were compared. Multivariate Cox regression analysis was performed to identify potential biomarkers for predicting disease progression. A concordance index (C-index), calibration curve, decision curve and the clinical impact curve were calculated to assess the predictive accuracy. Results: The data showed that the white blood cell count, neutrophil count and platelet count were normal on the day of hospital admission in most COVID-19 patients (87.9%, 85.1% and 88.7%, respectively). A total of 82.8% of severe patients had lymphopenia after the onset of symptoms, and as the disease progressed, there was marked lymphopenia. Multivariate Cox analysis showed that the neutrophil count (hazard ratio [HR] = 4.441, 95% CI = 1.954–10.090, p = 0.000), lymphocyte count (HR = 0.255, 95% CI = 0.097–0.669, p = 0.006) and platelet count (HR = 0.244, 95% CI = 0.111–0.537, p = 0.000) were independent risk factors for disease progression. The C-index (0.821 [95% CI, 0.746–0.896]), calibration curve, decision curve and the clinical impact curve showed that the nomogram can be used to predict the disease progression in COVID-19 patients accurately. In addition, the data involving the neutrophil count, lymphocyte count and platelet count (NLP score) have something to do with improving risk stratification and management of COVID-19 patients. Conclusions: We designed a clinically predictive tool which is easy to use for assessing the progression risk of COVID-19, and the NLP score could be used to facilitate patient stratification management. [ABSTRACT FROM AUTHOR]

The evolutionarily conserved serine/threonine kinase mTOR (mechanistic target of rapamycin) forms the distinct protein complexes mTORC1 and mTORC2 and integrates signals from the environment to coordinate downstream signaling events and various cellular processes. T cells rely on mTOR activity for their development and to establish their homeostasis and functional fitness. Here, we review recent progress in our understanding of the upstream signaling and downstream targets of mTOR. We also provide an updated overview of the roles of mTOR in T‐cell development, homeostasis, activation, and effector‐cell fate decisions, as well as its important impacts on the suppressive activity of regulatory T cells. Moreover, we summarize the emerging roles of mTOR in T‐cell exhaustion and transdifferentiation. A better understanding of the contribution of mTOR to T‐cell fate decisions will ultimately aid in the therapeutic targeting of mTOR in human disease. [ABSTRACT FROM AUTHOR]

Adoptive cell therapy represents a new paradigm in cancer immunotherapy, but it can be limited by the poor persistence and function of transferred T cells1. Here we use an in vivo pooled CRISPR–Cas9 mutagenesis screening approach to demonstrate that, by targeting REGNASE-1, CD8+ T cells are reprogrammed to long-lived effector cells with extensive accumulation, better persistence and robust effector function in tumours. REGNASE-1-deficient CD8+ T cells show markedly improved therapeutic efficacy against mouse models of melanoma and leukaemia. By using a secondary genome-scale CRISPR–Cas9 screening, we identify BATF as the key target of REGNASE-1 and as a rheostat that shapes antitumour responses. Loss of BATF suppresses the increased accumulation and mitochondrial fitness of REGNASE-1-deficient CD8+ T cells. By contrast, the targeting of additional signalling factors—including PTPN2 and SOCS1—improves the therapeutic efficacy of REGNASE-1-deficient CD8+ T cells. Our findings suggest that T cell persistence and effector function can be coordinated in tumour immunity and point to avenues for improving the efficacy of adoptive cell therapy for cancer. CRISPR–Cas9 mutagenesis screenings reveal that targeting REGNASE-1 leads to improved therapeutic efficacy of CD8+ T cells against mouse models of cancer, and identify BATF as a key target of REGNASE-1. [ABSTRACT FROM AUTHOR]

Regulatory T (Treg) cells are crucial for peripheral immune tolerance and prevention of autoimmunity and tissue damage. Treg cells are inherently defined by the expression of the transcription factor Foxp3, which enforces lineage development and immune suppressive function of these cells. Under various conditions as observed in autoimmunity, cancer and non-lymphoid tissues, a proportion of Treg cells respond to specific environmental signals and display altered stability, plasticity and tissue-specific heterogeneity, which further shape their context-dependent suppressive functions. Recent studies have revealed that metabolic programs play pivotal roles in controlling these processes in Treg cells, thereby considerably expanding our understanding of Treg cell biology. Here we summarize these recent advances that highlight how cell-extrinsic factors, such as nutrients, vitamins and metabolites, and cell-intrinsic metabolic programs, orchestrate Treg cell stability, plasticity, and tissue-specific heterogeneity. Understanding metabolic regulation of Treg cells should provide new insight into immune homeostasis and disease, with important therapeutic implications for autoimmunity, cancer, and other immune-mediated disorders. [ABSTRACT FROM AUTHOR]

The small-molecule modulators (agonists and antagonists) of peroxisome proliferator-activated receptor-γ (PPARγ) have been widely used to treat metabolic, cardiovascular and inflammatory diseases such as Type-2 diabetes and heart failure. Existing PPARγ modulators are all developed to target the ligand-binding site (LBS) in PPARγ ligand-binding domain (LBD) interior, where is spatially separated from the coactivator-interacting site (CIS) on PPARγ LBD surface and can thus only indirectly mediate the binding of NCOA1 coactivator peptide to CIS site. Here, we propose a new therapeutic strategy termed as Type-III PPARγ antagonists, which competitively disrupt the NCOA1 peptide binding by directly targeting PPARγ CIS site. Such antagonists are also known as inverse agonists that can partially or fully repress the basal transcriptional activity of PPARγ. A structure-based stepwise screening is performed against a purchasable biogenic compound library to identify CIS-specific binding competitors. The screening integrates empirical manual exclusion, druglikeness/pharmacokinetic evaluation, chemical similarity analysis and high-throughput molecular docking to rank the relative binding capability for compound candidate lists. The competitive potency of eight promising hits against a truncated version (core binding sequence) of full-length NCOA1 peptide (685ERHKILHRLLQEGSPS700) is tested using fluorescence competition assays. Consequently, two out of the eight tested compounds are determined as potential competitors with NCOA1 peptide for PPARγ CIS site, with CC50 values of 13 ± 1.8 and 54 ± 6.7 μM, respectively. Structural analysis reveals that the two competitor ligands are anchored at the central hole of CIS site through their substituted phenyl moieties, while forming a variety of hydrogen bonds, cation-π stacking and hydrophobic contacts with the regions surrounding the hole, conferring both stability and specificity to the CIS–competitor recognition and interaction. [ABSTRACT FROM AUTHOR]

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 amongst exhausted CD8-positive T cells in chronic infection1-3, but it remains unclear whether CD4-positive T-cell subsets with similar features exist in chronic inflammatory conditions. Amongst helper T cells, TH17 cells have prominent roles in autoimmunity and tissue inflammation and are characterized by inherent plasticity4-7, although how such plasticity is regulated is poorly understood. Here we demonstrate that TH17 cells in a mouse model of autoimmune disease are functionally and metabolically heterogeneous; they contain a subset with stemness-associated features but lower anabolic metabolism, and a reciprocal subset with higher metabolic activity that supports transdifferentiation into TH1-like cells. These two TH17-cell subsets are defined by selective expression of the transcription factors TCF-1 and T-bet, and by discrete levels of CD27 expression. We also identify signalling via the kinase complex mTORC1 as a central regulator of TH17-cell fate decisions by coordinating metabolic and transcriptional programmes. TH17 cells with disrupted mTORC1 signalling or anabolic metabolism fail to induce autoimmune neuroinflammation or to develop into TH1-like cells, but instead upregulate TCF-1 expression 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 loss of mTORC1 activity 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 plasticity in helper T cells. Phenotypically, transcriptionally and metabolically diverse subsets of TH17 cells develop in a chronic autoimmune disease: one subset has inferred stemness features and low anabolic metabolism, while a reciprocal subset has higher metabolic activity that supports transdifferentiation into TH1 cells. [ABSTRACT FROM AUTHOR]

The interaction between extrinsic factors and intrinsic signal strength governs thymocyte development, but the mechanisms linking them remain elusive. We report that mechanistic target of rapamycin complex 1 (mTORC1) couples microenvironmental cues with metabolic programs to orchestrate the reciprocal development of two fundamentally distinct T cell lineages, the αβ and γδ T cells. Developing thymocytes dynamically engage metabolic programs including glycolysis and oxidative phosphorylation, as well as mTORC1 signaling. Loss of RAPTOR-mediated mTORC1 activity impairs the development of αβ T cells but promotes γδ T cell generation, associated with disrupted metabolic remodeling of oxidative and glycolytic metabolism. Mechanistically, we identify mTORC1-dependent control of reactive oxygen species production as a key metabolic signal in mediating αβ and γδ T cell development, and perturbation of redox homeostasis impinges upon thymocyte fate decisions and mTORC1-associated phenotypes. Furthermore, single-cell RNA sequencing and genetic dissection reveal that mTORC1 links developmental signals from T cell receptors and NOTCH to coordinate metabolic activity and signal strength. Our results establish mTORC1-driven metabolic signaling as a decisive factor for reciprocal and αβ T γδ cell development and provide insight into metabolic control of cell signaling and fate decisions. [ABSTRACT FROM AUTHOR]

Dendritic cells orchestrate the crosstalk between innate and adaptive immunity. CD8α+ dendritic cells present antigens to CD8+ T cells and elicit cytotoxic T cell responses to viruses, bacteria and tumours [1]. Although lineage-specific transcriptional regulators of CD8α+ dendritic cell development have been identified [2], the molecular pathways that selectively orchestrate CD8α+ dendritic cell function remain elusive. Moreover, metabolic reprogramming is important for dendritic cell development and activation [3], [4], but metabolic dependence and regulation of dendritic cell subsets are largely uncharacterized. Here we use a data-driven systems biology algorithm (NetBID) to identify a role of the Hippo pathway kinases Mst1 and Mst2 (Mst1/2) in selectively programming CD8α+ dendritic cell function and metabolism. Our NetBID analysis reveals a marked enrichment of the activities of Hippo pathway kinases in CD8α+ dendritic cells relative to CD8α− dendritic cells. Dendritic cell-specific deletion of Mst1/2—but not Lats1 and Lats2 (Lats1/2) or Yap and Taz (Yap/Taz), which mediate canonical Hippo signalling—disrupts homeostasis and function of CD8+ T cells and anti-tumour immunity. Mst1/2-deficient CD8α+ dendritic cells are impaired in presentation of extracellular proteins and cognate peptides to prime CD8+ T cells, while CD8α− dendritic cells that lack Mst1/2 have largely normal function. Mechanistically, compared to CD8α− dendritic cells, CD8α+ dendritic cells exhibit much stronger oxidative metabolism and critically depend on Mst1/2 signalling to maintain bioenergetic activities and mitochondrial dynamics for their functional capacities. Further, selective expression of IL-12 by CD8α+ dendritic cells depends on Mst1/2 and the crosstalk with non-canonical NF-κB signalling. Our findings identify Mst1/2 as selective drivers of CD8α+ dendritic cell function by integrating metabolic activity and cytokine signalling, and highlight that the interplay between immune signalling and metabolic reprogramming underlies the unique functions of dendritic cell subsets. A data-driven analysis helps to identify specific roles of the Hippo signalling kinases Mst1 and Mst2 in integrating metabolic activity and cytokine signalling in dendritic cells, and thereby orchestrating immune cell function. [ABSTRACT FROM AUTHOR]

In order to understand the mode shift behavior of car travelers and relieve traffic congestion, a Stated Preference survey has been conducted in the city of Ji'nan in China to analyze bus choice behavior and the heterogeneity of car travelers. Several discrete choice models, including multinomial logit, mixed logit and latent class model (LCM) are developed based on these survey data. A comparative analysis indicates that the LCM has the highest precision and is more suitable to analyze the heterogeneity of car travelers. The LCM divides car travelers into three classes. Different classes have different sets of influencing factors in the model. Policy recommendations are also proposed for those classes to promote bus shift from car travelers based on the model results. Finally, sensitivity analysis on parking fees and fuel cost is carried out on the LCMs under different bus service levels. Car travelers have different sensitivities to the influencing factors. The conclusions indicate that the LCM can reflect the heterogeneity and preferences of car travelers and can be used to understand how to shift the behavior of car travelers and make more effective traffic policy. [ABSTRACT FROM PUBLISHER]

Regulatory T cells (Treg cells) have a pivotal role in the establishment and maintenance of immunological self-tolerance and homeostasis. Transcriptional programming of regulatory mechanisms facilitates the functional activation of Treg cells in the prevention of diverse types of inflammatory responses. It remains unclear how Treg cells orchestrate their homeostasis and interplay with environmental signals. Here we show that liver kinase B1 (LKB1) programs the metabolic and functional fitness of Treg cells in the control of immune tolerance and homeostasis. Mice with a Treg-specific deletion of LKB1 developed a fatal inflammatory disease characterized by excessive TH2-type-dominant responses. LKB1 deficiency disrupted Treg cell survival and mitochondrial fitness and metabolism, but also induced aberrant expression of immune regulatory molecules including the negative co-receptor PD-1 and the TNF receptor superfamily proteins GITR and OX40. Unexpectedly, LKB1 function in Treg cells was independent of conventional AMPK signalling or the mTORC1-HIF-1α axis, but contributed to the activation of β-catenin signalling for the control of PD-1 and TNF receptor proteins. Blockade of PD-1 activity reinvigorated the ability of LKB1-deficient Treg cells to suppress TH2 responses and the interplay with dendritic cells primed by thymic stromal lymphopoietin. Thus, Treg cells use LKB1 signalling to coordinate their metabolic and immunological homeostasis and to prevent apoptotic and functional exhaustion, thereby orchestrating the balance between immunity and tolerance. [ABSTRACT FROM AUTHOR]

The interplay between effector T cells and regulatory T cells (Treg cells) is crucial for adaptive immunity, but how Treg cells control diverse effector responses is elusive. We found that the phosphatase PTEN links Treg cell stability to repression of type 1 helper T cell (TH1 cell) and follicular helper T cell (TFH cell) responses. Depletion of PTEN in Treg cells resulted in excessive TFH cell and germinal center responses and spontaneous inflammatory disease. These defects were considerably blocked by deletion of interferon-γ, indicating coordinated control of TH1 and TFH responses. Mechanistically, PTEN maintained Treg cell stability and metabolic balance between glycolysis and mitochondrial fitness. Moreover, PTEN deficiency upregulates activity of the metabolic checkpoint kinase complex mTORC2 and the serine-threonine kinase Akt, and loss of this activity restores functioning of PTEN-deficient Treg cells. Our studies establish a PTEN-mTORC2 axis that maintains Treg cell stability and coordinates Treg cell-mediated control of effector responses. [ABSTRACT FROM AUTHOR]

Memory CD8+ T cells are an essential component of protective immunity. Signaling via mechanistic target of rapamycin (mTOR) has been implicated in the regulation of the differentiation of effector and memory T cells. However, little is understood about the mechanisms that control mTOR activity, or the effector pathways regulated by mTOR. We describe here that tuberous sclerosis 1 (Tsc1), a regulator of mTOR signaling, plays a crucial role in promoting the differentiation and function of memory CD8+ T cells in response to Listeria monocytogenes infection. Mice with specific deletion of Tsc1 in antigen-experienced CD8+ T cells evoked normal effector responses, but were markedly impaired in the generation of memory T cells and their recall responses to antigen reexposure in a cell-intrinsic manner. Tsc1 deficiency suppressed the generation of memory-precursor effector cells while promoting short-lived effector cell differentiation. Transcriptome analysis indicated that Tsc1 coordinated gene expression programs underlying immune function, transcriptional regulation, and cell metabolism. Furthermore, Tsc1 deletion led to excessive mTORC1 activity and dysregulated glycolytic and oxidative metabolism in response to IL-15 stimulation. These findings establish a Tsc1-mediated checkpoint in linking immune signaling and cell metabolism to orchestrate memory CD8+ T-cell development and function. [ABSTRACT FROM AUTHOR]

Dendritic cells (DCs) are a heterogeneous cell population of great importance in the immune system. The emergence of new genetic technology utilizing the CD11c promoter and Cre recombinase has facilitated the dissection of functional significance and molecular regulation of DCs in immune responses and homeostasis in vivo. For the first time, this strategy allows observation of the effects of DC-specific gene deletion on immune system function in an intact organism. In this review, we present the latest findings from studies using the Cre recombinase system for cell type-specific deletion of key molecules that mediate DC homeostasis and function. Our focus is on the molecular pathways that orchestrate DC life span, migration, antigen presentation, pattern recognition, and cytokine production and signaling. [ABSTRACT FROM AUTHOR]

Regulatory T cells (Treg cells) express members of the tumor-necrosis factor (TNF) receptor superfamily (TNFRSF), but the role of those receptors in the thymic development of Treg cells is undefined. We found here that Treg cell progenitors had high expression of the TNFRSF members GITR, OX40 and TNFR2. Expression of those receptors correlated directly with the signal strength of the T cell antigen receptor (TCR) and required the coreceptor CD28 and the kinase TAK1. The neutralization of ligands that are members of the TNF superfamily (TNFSF) diminished the development of Treg cells. Conversely, TNFRSF agonists enhanced the differentiation of Treg cell progenitors by augmenting responsiveness of the interleukin 2 receptor (IL-2R) and transcription factor STAT5. Costimulation with the ligand of GITR elicited dose-dependent enrichment for cells of lower TCR affinity in the Treg cell repertoire. In vivo, combined inhibition of GITR, OX40 and TNFR2 abrogated the development of Treg cells. Thus, expression of members of the TNFRSF on Treg cell progenitors translated strong TCR signals into molecular parameters that specifically promoted the development of Treg cells and shaped the Treg cell repertoire. [ABSTRACT FROM AUTHOR]

Highly pathogenic avian influenza viruses pose a continuing global threat. Current vaccines will not protect against newly evolved pandemic viruses. The creation of 'universal' vaccines has been unsuccessful because the immunological mechanisms that promote heterosubtypic immunity are incompletely defined. We found here that rapamycin, an immunosuppressive drug that inhibits the kinase mTOR, promoted cross-strain protection against lethal infection with influenza virus of various subtypes when administered during immunization with influenza virus subtype H3N2. Rapamycin reduced the formation of germinal centers and inhibited class switching in B cells, which yielded a unique repertoire of antibodies that mediated heterosubtypic protection. Our data established a requirement for the mTORC1 complex in B cell class switching and demonstrated that rapamycin skewed the antibody response away from high-affinity variant epitopes and targeted more conserved elements of hemagglutinin. Our findings have implications for the design of a vaccine against influenza virus. [ABSTRACT FROM AUTHOR]

The mechanistic target of rapamycin (mTOR) pathway integrates diverse environmental inputs, including immune signals and metabolic cues, to direct T-cell fate decisions. The activation of mTOR, which is the catalytic subunit of the mTORC1 and mTORC2 complexes, delivers an obligatory signal for the proper activation and differentiation of effector CD4+ T cells, whereas in the regulatory T-cell (Treg) compartment, the Akt-mTOR axis is widely acknowledged as a crucial negative regulator of Treg-cell de novo differentiation and population expansion. However, whether mTOR signalling affects the homeostasis and function of Treg cells remains largely unexplored. Here we show that mTORC1 signalling is a pivotal positive determinant of Treg-cell function in mice. Treg cells have elevated steady-state mTORC1 activity compared to naive T cells. Signals through the T-cell antigen receptor (TCR) and interleukin-2 (IL-2) provide major inputs for mTORC1 activation, which in turn programs the suppressive function of Treg cells. Disruption of mTORC1 through Treg-specific deletion of the essential component raptor leads to a profound loss of Treg-cell suppressive activity in vivo and the development of a fatal early onset inflammatory disorder. Mechanistically, raptor/mTORC1 signalling in Treg cells promotes cholesterol and lipid metabolism, with the mevalonate pathway particularly important for coordinating Treg-cell proliferation and upregulation of the suppressive molecules CTLA4 and ICOS to establish Treg-cell functional competency. By contrast, mTORC1 does not directly affect the expression of Foxp3 or anti- and pro-inflammatory cytokines in Treg cells, suggesting a non-conventional mechanism for Treg-cell functional regulation. Finally, we provide evidence that mTORC1 maintains Treg-cell function partly through inhibiting the mTORC2 pathway. Our results demonstrate that mTORC1 acts as a fundamental 'rheostat' in Treg cells to link immunological signals from TCR and IL-2 to lipogenic pathways and functional fitness, and highlight a central role of metabolic programming of Treg-cell suppressive activity in immune homeostasis and tolerance. [ABSTRACT FROM AUTHOR]

NOD2 receptor and the cytosolic protein kinase RIPK2 regulate NF-κB and MAP kinase signaling during bacterial infections, but the role of this immune axis during viral infections has not been addressed. We demonstrate that Nod2−/− and Ripk2−/− mice are hypersusceptible to infection with influenza A virus. Ripk2−/− cells exhibited defective autophagy of mitochondria (mitophagy), leading to enhanced mitochondrial production of superoxide and accumulation of damaged mitochondria, which resulted in greater activation of the NLRP3 inflammasome and production of IL-18. RIPK2 regulated mitophagy in a kinase-dependent manner by phosphorylating the mitophagy inducer ULK1. Accordingly, Ulk1−/− cells exhibited enhanced mitochondrial production of superoxide and activation of caspase-1. These results demonstrate a role for NOD2-RIPK2 signaling in protection against virally triggered immunopathology by negatively regulating activation of the NLRP3 inflammasome and production of IL-18 via ULK1-dependent mitophagy. [ABSTRACT FROM AUTHOR]

Dendritic cells (DC) are required for priming antigen-specific T cells and acquired immunity to many important human pathogens, including Mycobacteriuim tuberculosis (TB) and influenza. However, inappropriate priming of auto-reactive T cells is linked with autoimmune disease. Understanding the molecular mechanisms that regulate the priming and activation of naïve T cells is critical for development of new improved vaccines and understanding the pathogenesis of autoimmune diseases. The serine/threonine kinase IKKα (CHUK) has previously been shown to have anti-inflammatory activity and inhibit innate immunity. Here, we show that IKKα is required in DC for priming antigen-specific T cells and acquired immunity to the human pathogen Listeria monocytogenes. We describe a new role for IKKα in regulation of IRF3 activity and the functional maturation of DC. This presents a unique role for IKKα in dampening inflammation while simultaneously promoting adaptive immunity that could have important implications for the development of new vaccine adjuvants and treatment of autoimmune diseases. [ABSTRACT FROM AUTHOR]

The article discusses the role of c-Jun NH2 terminal kinase (JNK) signaling pathway that reduces the development of invasive adenocarcinoma in the phosphatase and tensin homolog (Pten) of prostate cancer. It reports that preventing JNK activation in the prostate epithelium causes rapid development of invasive adenocarcinoma. It reports that both JNK and PTEN signaling pathways cooperate to regulate the progression of prostate neoplasia to invasive adenocarcinoma.

The evolutionarily conserved kinase mTOR (mammalian target of rapamycin) couples cell growth and metabolism to environmental inputs in eukaryotes. T cells depend on mTOR signalling to integrate immune signals and metabolic cues for their proper maintenance and activation. Under steady-state conditions, mTOR is actively controlled by multiple inhibitory mechanisms, and this enforces normal T cell homeostasis. Antigen recognition by naive CD4+ and CD8+ T cells triggers mTOR activation, which in turn programmes the differentiation of these cells into functionally distinct lineages. This Review focuses on the signalling mechanisms of mTOR in T cell homeostatic and functional fates, and discusses the therapeutic implications of targeting mTOR in T cells. [ABSTRACT FROM AUTHOR]

Dendritic cells (DCs) bridge innate and adaptive immunity, but how DC-derived signals regulate T cell lineage choices remains unclear. We report here that the mitogen-activated protein kinase p38? programmed DCs to drive the differentiation of the TH17 subset of helper T cells. Deletion of p38? in DCs protected mice from TH17 cell-mediated autoimmune neuroinflammation, but deletion of p38? in macrophages or T cells did not. We also found that p38? orchestrated the expression of cytokines and costimulatory molecules in DCs and further 'imprinted' signaling via the receptor for interleukin 23 (IL-23R) in responding T cells to promote TH17 differentiation. Moreover, p38? was required for tissue-infiltrating DCs to sustain TH17 responses. This activity of p38? was conserved in mouse and human DCs and was dynamically regulated by pattern recognition and fungal infection. Our results identify p38? signaling as a central pathway for the integration of instructive signals in DCs for TH17 differentiation and inflammation. [ABSTRACT FROM AUTHOR]

The mechanisms that regulate T cell quiescence are poorly understood. We report that the tumor suppressor Tsc1 established a quiescence program in naive T cells by controlling cell size, cell cycle entry and responses to stimulation of the T cell antigen receptor. Abrogation of quiescence predisposed Tsc1-deficient T cells to apoptosis that resulted in loss of conventional T cells and invariant natural killer T cells. Loss of Tsc1 function dampened in vivo immune responses to bacterial infection. Tsc1-deficient T cells had more activity of the serine-threonine kinase complex mTORC1 but less mTORC2 activity, and activation of mTORC1 was essential for the disruption of immune homeostasis. Therefore, Tsc1-dependent control of mTOR is crucial in actively maintaining the quiescence of naive T cells to facilitate adaptive immune function. [ABSTRACT FROM AUTHOR]

Naive CD4+ T cells differentiate into diverse effector and regulatory lineages to orchestrate immunity and tolerance. Here we found that the differentiation of proinflammatory T helper type 1 (TH1) cells and anti-inflammatory Foxp3+ regulatory T cells (Treg cells) was reciprocally regulated by S1P1, a receptor for the bioactive lipid sphingosine 1-phosphate (S1P). S1P1 inhibited the generation of extrathymic and natural Treg cells while driving TH1 development in a reciprocal manner and disrupted immune homeostasis. S1P1 signaled through the kinase mTOR and antagonized the function of transforming growth factor-β mainly by attenuating sustained activity of the signal transducer Smad3. S1P1 function was dependent on endogenous sphingosine kinase activity. Notably, two seemingly unrelated immunosuppressants, FTY720 and rapamycin, targeted the same S1P1 and mTOR pathway to regulate the dichotomy between TH1 cells and Treg cells. Our studies establish an S1P1-mTOR axis that controls T cell lineage specification. [ABSTRACT FROM AUTHOR]

Engagement of antigen receptors triggers the proliferation and functional activation of lymphocytes. Here we report that T cell homeostasis and antigen-induced responses require the COP9 signalosome (CSN), a regulator of the ubiquitin-proteasome system. Conditional deletion of the CSN subunit Csn8 in peripheral T lymphocytes disrupted formation of the CSN complex, reduced T cell survival and proliferation in vivo and impaired antigen-induced production of interleukin 2. Moreover, Csn8-deficient T cells showed defective entry into the cell cycle from the G0 quiescent state. This phenotype was associated with a lack of signal-induced expression of cell cycle–related genes, including G1 cyclins and cyclin-dependent kinases, and with excessive induction of p21Cip1. Our data define a CSN-dependent pathway of transcriptional control that is essential for antigen-induced initiation of T cell proliferation. [ABSTRACT FROM AUTHOR]

Innate immune responses mediated by macrophages and dendritic cells through Toll-like receptors (TLRs) play a central role in sensing and eliminating microbial pathogens. However, excessive innate immune responses can result in sepsis, autoimmunity, and chronic inflammation. Cells have evolved multiple mechanisms to prevent deleterious TLR activation, including transcriptional induction of intracellular negative regulators. Mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP-1) is a nuclear-localized dual-specificity phosphatase that is induced by TLR stimulation in macrophages. MKP-1 preferentially dephosphorylates p38 MAPK and c-Jun N-terminal kinase, resulting in the attenuation of TLR-triggered production of pro-inflammatory cytokines and other inflammatory mediators. MKP-1 deficiency in mice leads to a markedly elevated susceptibility to endotoxic shock (a murine model of sepsis) and autoimmune arthritis, highlighting a key role for MKP-1 in regulating innate immunity. Herein we discuss biochemical activities and physiological functions of MKP-1 and the regulation of its expression in TLR-mediated innate immune responses. [ABSTRACT FROM AUTHOR]

The stress-inducible molecules GADD45ß and GADD45? have been implicated in regulating IFN? production in CD4 T cells. However, how GADD45 proteins function has been controversial. MEKK4 is a MAP kinase kinase kinase that interacts with GADD45 in vitro. Here we generated MEKK4-deficient mice to define the function and regulation of this pathway. CD4 T cells from MEKK4-/- mice have reduced p38 activity and defective IFN? synthesis. Expression of GADD45ß or GADD45? promotes IFN? production in MEKK4+/+ T cells, but not in MEKK4-/- cells or in cells treated with a p38 inhibitor. Thus, MEKK4 mediates the action of GADD45ß and GADD45? on p38 activation and IFN? production. During Th1 differentiation, the GADD45ß/GADD45?/MEKK4 pathway appears to integrate upstream signals transduced by both T cell receptor and IL12/STAT4, leading to augmented IFN? production in a process independent of STAT4. [ABSTRACT FROM AUTHOR]

Damaged or foreign DNA stimulates immune responses by inducing the production of interferon proteins. New evidence indicates that this response is mediated by a cytosolic DNA sensor known as DAI. [ABSTRACT FROM AUTHOR]