Disturbed mitochondrial dynamics in CD8+ TILs reinforce T cell exhaustion

Stem-like T cells in cancer and autoimmunity

Stem-like T cells are characterized by their ability to self-renew, survive long-term, and give rise to a heterogeneous pool of effector and memory T cells. Recent advances in single-cell RNA-sequencing (scRNA-seq) and lineage tracing technologies revealed an important role for stem-like T cells in both autoimmunity and cancer. In cancer, stem-like T cells constitute an important arm of the anti-tumor immune response by giving rise to effector T cells that mediate tumor control. In contrast, in autoimmunity stem-like T cells perform an unfavorable role by forming a reservoir of long-lived autoreactive cells that replenish the pathogenic, effector T-cell pool and thereby driving disease pathology. This review provides background on the discovery of stem-like T cells and their function in cancer and autoimmunity. Moreover, the influence of the microbiota and metabolism on the stem-like T-cell pool is summarized. Lastly, the implications of our knowledge about stem-like T cells for clinical treatment strategies for cancer and autoimmunity will be discussed.

Selective refueling of CAR T cells using ADA1 and CD26 boosts antitumor immunity

Chimeric antigen receptor (CAR) T cell therapy is hindered in solid tumor treatment due to the immunosuppressive tumor microenvironment and suboptimal T cell persistence. Current strategies do not address nutrient competition in the microenvironment. Hence, we present a metabolic refueling approach using inosine as an alternative fuel. CAR T cells were engineered to express membrane-bound CD26 and cytoplasmic adenosine deaminase 1 (ADA1), converting adenosine to inosine. Autocrine secretion of ADA1 upon CD3/CD26 stimulation activates CAR T cells, improving migration and resistance to transforming growth factor β1 suppression. Fusion of ADA1 with anti-CD3 scFv further boosts inosine production and minimizes tumor cell feeding. In mouse models of hepatocellular carcinoma and non-small cell lung cancer, metabolically refueled CAR T cells exhibit superior tumor reduction compared to unmodified CAR T cells. Overall, our study highlights the potential of selective inosine refueling to enhance CAR T therapy efficacy against solid tumors.

Altered cancer metabolism and implications for next-generation CAR T-cell therapies

This review critically examines the evolving landscape of chimeric antigen receptor (CAR) T-cell therapy in treating solid tumors, with a particular focus on the metabolic challenges within the tumor microenvironment. CAR T-cell therapy has demonstrated remarkable success in hematologic malignancies, yet its efficacy in solid tumors remains limited. A significant barrier is the hostile milieu of the tumor microenvironment, which impairs CAR T-cell survival and function. This review delves into the metabolic adaptations of cancer cells and their impact on immune cells, highlighting the competition for nutrients and the accumulation of immunosuppressive metabolites. It also explores emerging strategies to enhance CAR T-cell metabolic fitness and persistence, including genetic engineering and metabolic reprogramming. An integrated approach, combining metabolic interventions with CAR T-cell therapy, has the potential to overcome these constraints and improve therapeutic outcomes in solid tumors.

Metabolic rewiring and communication in cancer immunity

The immune system shapes tumor development and progression. Although immunotherapy has transformed cancer treatment, its overall efficacy remains limited, underscoring the need to uncover mechanisms to improve therapeutic effects. Metabolism-associated processes, including intracellular metabolic reprogramming and intercellular metabolic crosstalk, are emerging as instructive signals for anti-tumor immunity. Here, we first summarize the roles of intracellular metabolic pathways in controlling immune cell function in the tumor microenvironment. How intercellular metabolic communication regulates anti-tumor immunity, and the impact of metabolites or nutrients on signaling events, are also discussed. We then describe how targeting metabolic pathways in tumor cells or intratumoral immune cells or via nutrient-based interventions may boost cancer immunotherapies. Finally, we conclude with discussions on profiling and functional perturbation methods of metabolic activity in intratumoral immune cells, and perspectives on future directions. Uncovering the mechanisms for metabolic rewiring and communication in the tumor microenvironment may enable development of novel cancer immunotherapies.

Targeting squalene epoxidase restores anti-PD-1 efficacy in metabolic dysfunction-associated steatohepatitis-induced hepatocellular carcinoma

OBJECTIVE

Squalene epoxidase (SQLE) promotes metabolic dysfunction-associated steatohepatitis-associated hepatocellular carcinoma (MASH-HCC), but its role in modulating the tumour immune microenvironment in MASH-HCC remains unclear.

DESIGN

We established hepatocyte-specific Sqle transgenic (tg) and knockout mice, which were subjected to a choline-deficient high-fat diet plus diethylnitrosamine to induce MASH-HCC. SQLE function was also determined in orthotopic and humanised mice. Immune landscape alterations of MASH-HCC mediated by SQLE were profiled by single-cell RNA sequencing and flow cytometry.

RESULTS

Hepatocyte-specific Sqle tg mice exhibited a marked increase in MASH-HCC burden compared with wild-type littermates, together with decreased tumour-infiltrating functional IFN-γ+ and Granzyme B+ CD8+ T cells while enriching Arg-1+ myeloid-derived suppressor cells (MDSCs). Conversely, hepatocyte-specific Sqle knockout suppressed tumour growth with increased cytotoxic CD8+ T cells and reduced Arg-1+ MDSCs, inferring that SQLE promotes immunosuppression in MASH-HCC. Mechanistically, SQLE-driven cholesterol accumulation in tumour microenvironment underlies its effect on CD8+ T cells and MDSCs. SQLE and its metabolite, cholesterol, impaired CD8+ T cell activity by inducing mitochondrial dysfunction. Cholesterol depletion in vitro abolished the effect of SQLE-overexpressing MASH-HCC cell supernatant on CD8+ T cell suppression and MDSC activation, whereas cholesterol supplementation had contrasting functions on CD8+ T cells and MDSCs treated with SQLE-knockout supernatant. Targeting SQLE with genetic ablation or pharmacological inhibitor, terbinafine, rescued the efficacy of anti-PD-1 treatment in MASH-HCC models.

CONCLUSION

SQLE induces an impaired antitumour response in MASH-HCC via attenuating CD8+ T cell function and augmenting immunosuppressive MDSCs. SQLE is a promising target in boosting anti-PD-1 immunotherapy for MASH-HCC.

Impact of Drp1-regulated changes in T cell activity on the combined antitumor effects of PARPi and PD-1 inhibitors

This study aimed to investigate the influence of dynamin-related protein 1 (Drp1)-regulated T cells on the antitumor effects of poly (ADP-ribose) polymerase inhibitors (PARPi) combined with programmed cell death protein 1 (PD-1) inhibitors to identify potential targets for enhancing immunotherapy efficacy. We found that T cells with high expression of Drp1 promoted the inhibitory and killing effects of the PARPi and PD-1 inhibitor combination on lung cancer cells in vivo and in vitro. This synergistic mechanism involves Drp1-regulated promotion of activation, migration, and intratumor infiltration of effector T cells; inhibition of negative immunomodulatory cells in the tumor microenvironment; and suppression of PARPi-induced upregulation of PD-L1 expression in tumor cells. These findings suggest that Drp1 could serve as a new target for comprehensively improving the tumor microenvironment, enhancing immunotherapy efficacy, and reversing immunotherapy resistance.

Urolithin-A Promotes CD8+ T Cell-mediated Cancer Immunosurveillance via FOXO1 Activation

Naïve T cells are key players in cancer immunosurveillance, even though their function declines during tumor progression. Thus, interventions capable of sustaining the quality and function of naïve T cells are needed to improve cancer immunoprevention.In this context, we studied the capacity of Urolithin-A (UroA), a potent mitophagy inducer, to enhance T cell-mediated cancer immunosurveillance.We discovered that UroA improved the cancer immune response by activating the transcription factor FOXO1 in CD8+ T cell. Sustained FOXO1 activation promoted the expression of the adhesion molecule L-selectin (CD62L) resulting in the expansion of the naïve T cells population. We found that UroA reduces FOXO1 phosphorylation favoring its nuclear localization and transcriptional activity. Overall, our findings determine FOXO1 as a novel molecular target of UroA in CD8+ T cells and indicate UroA as promising immunomodulator to improve cancer immunosurveillance.

SIGNIFICANCE

Urolithin-A, a potent mitophagy inducer, emerges as a promising tool to enhance cancer immunosurveillance by activating the FOXO1 transcription factor in CD8+ T cells. This activation promotes the expansion of naïve T cells, offering a novel avenue for improving cancer immune response and highlighting UroA as a potential immunomodulator for bolstering our body's defenses against cancer.

PGE2 inhibits TIL expansion by disrupting IL-2 signalling and mitochondrial function

Expansion of antigen-experienced CD8+ T cells is critical for the success of tumour-infiltrating lymphocyte (TIL)-adoptive cell therapy (ACT) in patients with cancer1. Interleukin-2 (IL-2) acts as a key regulator of CD8+ cytotoxic T lymphocyte functions by promoting expansion and cytotoxic capability2,3. Therefore, it is essential to comprehend mechanistic barriers to IL-2 sensing in the tumour microenvironment to implement strategies to reinvigorate IL-2 responsiveness and T cell antitumour responses. Here we report that prostaglandin E2 (PGE2), a known negative regulator of immune response in the tumour microenvironment4,5, is present at high concentrations in tumour tissue from patients and leads to impaired IL-2 sensing in human CD8+ TILs via the PGE2 receptors EP2 and EP4. Mechanistically, PGE2 inhibits IL-2 sensing in TILs by downregulating the IL-2Rγc chain, resulting in defective assembly of IL-2Rβ-IL2Rγc membrane dimers. This results in impaired IL-2-mTOR adaptation and PGC1α transcriptional repression, causing oxidative stress and ferroptotic cell death in tumour-reactive TILs. Inhibition of PGE2 signalling to EP2 and EP4 during TIL expansion for ACT resulted in increased IL-2 sensing, leading to enhanced proliferation of tumour-reactive TILs and enhanced tumour control once the cells were transferred in vivo. Our study reveals fundamental features that underlie impairment of human TILs mediated by PGE2 in the tumour microenvironment. These findings have therapeutic implications for cancer immunotherapy and cell therapy, and enable the development of targeted strategies to enhance IL-2 sensing and amplify the IL-2 response in TILs, thereby promoting the expansion of effector T cells with enhanced therapeutic potential.

Immunometabolism of CD8+ T cell differentiation in cancer

CD8+ cytotoxic T lymphocytes (CTLs) are central mediators of tumor immunity and immunotherapies. Upon tumor antigen recognition, CTLs differentiate from naive/memory-like toward terminally exhausted populations with more limited function against tumors. Such differentiation is regulated by both immune signals, including T cell receptors (TCRs), co-stimulation, and cytokines, and metabolism-associated processes. These immune signals shape the metabolic landscape via signaling, transcriptional and post-transcriptional mechanisms, while metabolic processes in turn exert spatiotemporal effects to modulate the strength and duration of immune signaling. Here, we review the bidirectional regulation between immune signals and metabolic processes, including nutrient uptake and intracellular metabolic pathways, in shaping CTL differentiation and exhaustion. We also discuss the mechanisms underlying how specific nutrient sources and metabolite-mediated signaling events orchestrate CTL biology. Understanding how metabolic programs and their interplay with immune signals instruct CTL differentiation and exhaustion is crucial to uncover tumor-immune interactions and design novel immunotherapies.

Principles and therapeutic applications of adaptive immunity

Adaptive immunity provides protection against infectious and malignant diseases. These effects are mediated by lymphocytes that sense and respond with targeted precision to perturbations induced by pathogens and tissue damage. Here, we review key principles underlying adaptive immunity orchestrated by distinct T cell and B cell populations and their extensions to disease therapies. We discuss the intracellular and intercellular processes shaping antigen specificity and recognition in immune activation and lymphocyte functions in mediating effector and memory responses. We also describe how lymphocytes balance protective immunity against autoimmunity and immunopathology, including during immune tolerance, response to chronic antigen stimulation, and adaptation to non-lymphoid tissues in coordinating tissue immunity and homeostasis. Finally, we discuss extracellular signals and cell-intrinsic programs underpinning adaptive immunity and conclude by summarizing key advances in vaccination and engineering adaptive immune responses for therapeutic interventions. A deeper understanding of these principles holds promise for uncovering new means to improve human health.

The potential role of CMC1 as an immunometabolic checkpoint in T cell immunity

T cell immunity is critical for human defensive immune response. Exploring the key molecules during the process provides new targets for T cell-based immunotherapies. CMC1 is a mitochondrial electron transport chain (ETC) complex IV chaperon protein. By establishing in-vitro cell culture system and Cmc1 gene knock out mice, we evaluated the role of CMC1 in T cell activation and differentiation. The B16-OVA tumor model was used to test the possibility of targeting CMC1 for improving T cell anti-tumor immunity. We identified CMC1 as a positive regulator in CD8+T cells activation and terminal differentiation. Meanwhile, we found that CMC1 increasingly expressed in exhausted T (Tex) cells. Genetic lost of Cmc1 inhibits the development of CD8+T cell exhaustion in mice. Instead, deletion of Cmc1 in T cells prompts cells to differentiate into metabolically and functionally quiescent cells with increased memory-like features and tolerance to cell death upon repetitive or prolonged T cell receptor (TCR) stimulation. Further, the in-vitro mechanistic study revealed that environmental lactate enhances CMC1 expression by inducing USP7, mediated stabilization and de-ubiquitination of CMC1 protein, in which a mechanism we propose here that the lactate-enriched tumor microenvironment (TME) drives CD8+TILs dysfunction through CMC1 regulatory effects on T cells. Taken together, our study unraveled the novel role of CMC1 as a T cell regulator and its possibility to be utilized for anti-tumor immunotherapy.

Signaling by Type I Interferons in Immune Cells: Disease Consequences

This review addresses interferon (IFN) signaling in immune cells and the tumor microenvironment (TME) and examines how this affects cancer progression. The data reveal that IFNs exert dual roles in cancers, dependent on the TME, exhibiting both anti-tumor activity and promoting cancer progression. We discuss the abnormal IFN signaling induced by cancerous cells that alters immune responses to permit their survival and proliferation.

Identification and validation of a lactate metabolism-related six-gene prognostic signature in intrahepatic cholangiocarcinoma

PURPOSE

Intrahepatic cholangiocarcinoma (iCCA) is a highly malignant and fatal liver tumor with increasing incidence worldwide. Lactate metabolism has been recently reported as a crucial contributor to tumor progression and immune regulation in the tumor microenvironment. However, it remains poorly identified about the biological functions of lactate metabolism in iCCA, which hinders the development of prognostic tools and therapeutic interventions.

METHODS

The univariate Cox regression analysis and Boruta algorithm were utilized to identify key lactate metabolism-related genes (LMRGs), and a prognostic signature was constructed based on LMRG scores. Genomic variations and immune cell infiltration were evaluated in the high and low LMRG score groups. Finally, the biological functions of key LMRGs were verified with in vitro and in vivo experiments.

RESULTS

Patients in the high LMRG score group exhibit a poor prognosis compared to those in the low LMRG score group, with a high frequency of TP53 and KRAS mutations. Moreover, the infiltration and function of NK cells were compromised in the high LMRG score group, consistent with the results from two independent single-cell RNA sequencing datasets and immunohistochemistry of tissue microarrays. Experimental data revealed that lactate dehydrogenase A (LDHA) knockdown inhibited proliferation and migration in iCCA cell lines and tumor growth in immunocompetent mice.

CONCLUSION

Our study revealed the biological roles of LDHA in iCCA and developed a reliable lactate metabolism-related prognostic signature for iCCA, offering promising therapeutic targets for iCCA in the clinic.

Metabolic plasticity of T cell fate decision

ABSTRACT

The efficacy of adaptive immune responses in cancer treatment relies heavily on the state of the T cells. Upon antigen exposure, T cells undergo metabolic reprogramming, leading to the development of functional effectors or memory populations. However, within the tumor microenvironment (TME), metabolic stress impairs CD8 + T cell anti-tumor immunity, resulting in exhausted differentiation. Recent studies suggested that targeting T cell metabolism could offer promising therapeutic opportunities to enhance T cell immunotherapy. In this review, we provide a comprehensive summary of the intrinsic and extrinsic factors necessary for metabolic reprogramming during the development of effector and memory T cells in response to acute and chronic inflammatory conditions. Furthermore, we delved into the different metabolic switches that occur during T cell exhaustion, exploring how prolonged metabolic stress within the TME triggers alterations in cellular metabolism and the epigenetic landscape that contribute to T cell exhaustion, ultimately leading to a persistently exhausted state. Understanding the intricate relationship between T cell metabolism and cancer immunotherapy can lead to the development of novel approaches to improve the efficacy of T cell-based treatments against cancer.

Unlocking potential: the role of the electron transport chain in immunometabolism

The electron transport chain (ETC) couples electron transfer with proton pumping to generate ATP and it also regulates particular innate and adaptive immune cell function. While NLRP3 inflammasome activation was initially linked to reactive oxygen species (ROS) produced from Complexes I and III, recent research suggests that an intact ETC fueling ATP is needed. Complex II may be responsible for Th1 cell proliferation and in some cases, effector cytokine production. Complex III is required for regulatory T (Treg) cell function, while oxidative phosphorylation (OXPHOS) and Complexes I, IV, and V sustain proliferation and antibody production in B lymphocytes, with OXPHOS also being required for B regulatory (Breg) cell function. Despite challenges, the ETC shows therapeutic targeting potential for immune-related diseases and in immuno-oncology.

Targeting NAD+ Metabolism to Modulate Autoimmunity and Inflammation

NAD+ biology is involved in controlling redox balance, functioning as a coenzyme in numerous enzymatic reactions, and is a cofactor for Sirtuin enzymes and a substrate for multiple regulatory enzyme reactions within and outside the cell. At the same time, NAD+ levels are diminished with aging and are consumed during the development of inflammatory and autoimmune diseases linked to aberrant immune activation. Direct NAD+ augmentation via the NAD+ salvage and Priess-Handler pathways is being investigated as a putative therapeutic intervention to improve the healthspan in inflammation-linked diseases. In this review, we survey NAD+ biology and its pivotal roles in the regulation of immunity and inflammation. Furthermore, we discuss emerging studies evaluate NAD+ boosting in murine models and in human diseases, and we highlight areas of research that remain unresolved in understanding the mechanisms of action of these nutritional supplementation strategies.

Bioorthogonal photocatalytic proximity labeling in primary living samples

In situ profiling of subcellular proteomics in primary living systems, such as native tissues or clinic samples, is crucial for understanding life processes and diseases, yet challenging due to methodological obstacles. Here we report CAT-S, a bioorthogonal photocatalytic chemistry-enabled proximity labeling method, that expands proximity labeling to a wide range of primary living samples for in situ profiling of mitochondrial proteomes. Powered by our thioQM labeling warhead development and targeted bioorthogonal photocatalytic chemistry, CAT-S enables the labeling of mitochondrial proteins in living cells with high efficiency and specificity. We apply CAT-S to diverse cell cultures, dissociated mouse tissues as well as primary T cells from human blood, portraying the native-state mitochondrial proteomic characteristics, and unveiled hidden mitochondrial proteins (PTPN1, SLC35A4 uORF, and TRABD). Furthermore, CAT-S allows quantification of proteomic perturbations on dysfunctional tissues, exampled by diabetic mouse kidneys, revealing the alterations of lipid metabolism that may drive disease progression. Given the advantages of non-genetic operation, generality, and spatiotemporal resolution, CAT-S may open exciting avenues for subcellular proteomic investigations of primary samples that are otherwise inaccessible.

GSNOR overexpression enhances CAR-T cell stemness and anti-tumor function by enforcing mitochondrial fitness

Chimeric antigen receptor-T (CAR-T) cell has been developed as a promising agent for patients with refractory or relapsed lymphoma and leukemia, but not all the recipients could achieve a long-lasting remission. The limited capacity of in vivo expansion and memory differentiation post activation is one of the major reasons for suboptimal CAR-T therapeutic efficiency. Nitric oxide (NO) plays multifaceted roles in mitochondrial dynamics and T cell activation, but its function on CAR-T cell persistence and anti-tumor efficacy remains unknown. Herein, we found the continuous signaling from CAR not only promotes excessive NO production, but also suppressed S-nitrosoglutathione reductase (GSNOR) expression in T cells, which collectively led to increased protein S-nitrosylation, resulting in impaired mitochondrial fitness and deficiency of T cell stemness. Intriguingly, enforced expression of GSNOR promoted memory differentiation of CAR-T cell after immune activation, rendered CAR-T better resistance to mitochondrial dysfunction, further enhanced CAR-T cell expansion and anti-tumor capacity in vitro and in a mouse tumor model. Thus, we revealed a critical role of NO in restricting CAR-T cell persistence and functionality, and defined that GSNOR overexpression may provide a solution to combat NO stress and render patients with more durable protection from CAR-T therapy.

Disrupting CD38-driven T cell dysfunction restores sensitivity to cancer immunotherapy

A central problem in cancer immunotherapy with immune checkpoint blockade (ICB) is the development of resistance, which affects 50% of patients with metastatic melanoma1,2. T cell exhaustion, resulting from chronic antigen exposure in the tumour microenvironment, is a major driver of ICB resistance3. Here, we show that CD38, an ecto-enzyme involved in nicotinamide adenine dinucleotide (NAD+) catabolism, is highly expressed in exhausted CD8+ T cells in melanoma and is associated with ICB resistance. Tumour-derived CD38hiCD8+ T cells are dysfunctional, characterised by impaired proliferative capacity, effector function, and dysregulated mitochondrial bioenergetics. Genetic and pharmacological blockade of CD38 in murine and patient-derived organotypic tumour models (MDOTS/PDOTS) enhanced tumour immunity and overcame ICB resistance. Mechanistically, disrupting CD38 activity in T cells restored cellular NAD+ pools, improved mitochondrial function, increased proliferation, augmented effector function, and restored ICB sensitivity. Taken together, these data demonstrate a role for the CD38-NAD+ axis in promoting T cell exhaustion and ICB resistance, and establish the efficacy of CD38 directed therapeutic strategies to overcome ICB resistance using clinically relevant, patient-derived 3D tumour models.

Ex vivo activation of the GCN2 pathway metabolically reprograms T cells, leading to enhanced adoptive cell therapy

The manipulation of T cell metabolism to enhance anti-tumor activity is an area of active investigation. Here, we report that activating the amino acid starvation response in effector CD8+ T cells ex vivo using the general control non-depressible 2 (GCN2) agonist halofuginone (halo) enhances oxidative metabolism and effector function. Mechanistically, we identified autophagy coupled with the CD98-mTOR axis as key downstream mediators of the phenotype induced by halo treatment. The adoptive transfer of halo-treated CD8+ T cells into tumor-bearing mice led to robust tumor control and curative responses. Halo-treated T cells synergized in vivo with a 4-1BB agonistic antibody to control tumor growth in a mouse model resistant to immunotherapy. Importantly, treatment of human CD8+ T cells with halo resulted in similar metabolic and functional reprogramming. These findings demonstrate that activating the amino acid starvation response with the GCN2 agonist halo can enhance T cell metabolism and anti-tumor activity.

The nutrient-sensing Rag-GTPase complex in B cells controls humoral immunity via TFEB/TFE3-dependent mitochondrial fitness

During the humoral immune response, B cells undergo rapid metabolic reprogramming with a high demand for nutrients, which are vital to sustain the formation of the germinal centers (GCs). Rag-GTPases sense amino acid availability to modulate the mechanistic target of rapamycin complex 1 (mTORC1) pathway and suppress transcription factor EB (TFEB) and transcription factor enhancer 3 (TFE3), members of the microphthalmia (MiT/TFE) family of HLH-leucine zipper transcription factors. However, how Rag-GTPases coordinate amino acid sensing, mTORC1 activation, and TFEB/TFE3 activity in humoral immunity remains undefined. Here, we show that B cell-intrinsic Rag-GTPases are critical for the development and activation of B cells. RagA/RagB deficient B cells fail to form GCs, produce antibodies, and generate plasmablasts in both T-dependent (TD) and T-independent (TI) humoral immune responses. Deletion of RagA/RagB in GC B cells leads to abnormal dark zone (DZ) to light zone (LZ) ratio and reduced affinity maturation. Mechanistically, the Rag-GTPase complex constrains TFEB/TFE3 activity to prevent mitophagy dysregulation and maintain mitochondrial fitness in B cells, which are independent of canonical mTORC1 activation. TFEB/TFE3 deletion restores B cell development, GC formation in Peyer's patches and TI humoral immunity, but not TD humoral immunity in the absence of Rag-GTPases. Collectively, our data establish Rag-GTPase-TFEB/TFE3 pathway as an mTORC1 independent mechanism to coordinating nutrient sensing and mitochondrial metabolism in B cells.

Cytotoxic response of tumor-infiltrating lymphocytes of head and neck cancer slice cultures under mitochondrial dysfunction

Background

Head and neck squamous cell carcinomas (HNSCC) are highly heterogeneous tumors. In the harsh tumor microenvironment (TME), metabolic reprogramming and mitochondrial dysfunction may lead to immunosuppressive phenotypes. Aerobic glycolysis is needed for the activation of cytotoxic T-cells and the absence of glucose may hamper the full effector functions of cytotoxic T-cells. To test the effect of mitochondrial dysfunction on cytotoxic T cell function, slice cultures (SC) of HNSCC cancer were cultivated under different metabolic conditions.

Methods

Tumor samples from 21 patients with HNSCC were collected, from which, SC were established and cultivated under six different conditions. These conditions included high glucose, T cell stimulation, and temporarily induced mitochondrial dysfunction (MitoDys) using FCCP and oligomycin A with or without additional T cell stimulation, high glucose and finally, a control medium. Over three days of cultivation, sequential T cell stimulation and MitoDys treatments were performed. Supernatant was collected, and SC were fixed and embedded. Granzyme B was measured in the supernatant and in the SC via immunohistochemistry (IHC). Staining of PD1, CD8/Ki67, and cleaved-caspase-3 (CC3) were performed in SC.

Results

Hematoxylin eosin stains showed that overall SC quality remained stable over 3 days of cultivation. T cell stimulation, both alone and combined with MitoDys, led to significantly increased granzyme levels in SC and in supernatant. Apoptosis following T cell stimulation was observed in tumor and stroma. Mitochondrial dysfunction alone increased apoptosis in tumor cell aggregates. High glucose concentration alone had no impact on T cell activity and apoptosis. Apoptosis rates were significantly lower under conditions with high glucose and MitoDys (p=0.03).

Conclusion

Stimulation of tumor-infiltrating lymphocytes in SC was feasible, which led to increased apoptosis in tumor cells. Induced mitochondrial dysfunction did not play a significant role in the activation and function of TILs in SC of HNSCC. Moreover, high glucose concentration did not promote cytotoxic T cell activity in HNSCC SC.

Advances in reprogramming of energy metabolism in tumor T cells

Cancer is a leading cause of human death worldwide, and the modulation of the metabolic properties of T cells employed in cancer immunotherapy holds great promise for combating cancer. As a crucial factor, energy metabolism influences the activation, proliferation, and function of T cells, and thus metabolic reprogramming of T cells is a unique research perspective in cancer immunology. Special conditions within the tumor microenvironment and high-energy demands lead to alterations in the energy metabolism of T cells. In-depth research on the reprogramming of energy metabolism in T cells can reveal the mechanisms underlying tumor immune tolerance and provide important clues for the development of new tumor immunotherapy strategies as well. Therefore, the study of T cell energy metabolism has important clinical significance and potential applications. In the study, the current achievements in the reprogramming of T cell energy metabolism were reviewed. Then, the influencing factors associated with T cell energy metabolism were introduced. In addition, T cell energy metabolism in cancer immunotherapy was summarized, which highlighted its potential significance in enhancing T cell function and therapeutic outcomes. In summary, energy exhaustion of T cells leads to functional exhaustion, thus resulting in immune evasion by cancer cells. A better understanding of reprogramming of T cell energy metabolism may enable immunotherapy to combat cancer and holds promise for optimizing and enhancing existing therapeutic approaches.

Enhanced T cell immune activity mediated by Drp1 promotes the efficacy of PD-1 inhibitors in treating lung cancer

BACKGROUND

Dynamin-related protein 1 (Drp1)-mediated mitochondrial fission plays important roles in the activation, proliferation, and migration of T cells.

METHODS

We investigated the synergistic effect of Drp1-mediated T cell antitumor activities and programmed cell death protein 1 (PD-1) blockade for treating lung cancer through in vitro co-culture experiments and an in vivo nude mouse xenograft model.

RESULTS

High expression levels of Drp1 positively regulated T cell activation, enhanced T cell-induced suppression of lung cancer cells, promoted CD8+ T cell infiltration in the tumor and spleen, and significantly enhanced the antitumor immune response of the PD-1 inhibitor pembrolizumab. The mechanism of this synergistic antitumor effect involved the secretion of immune killing-related cytokines and the regulation of the PD-1-ERK/Drp1 pathway in T cells.

CONCLUSIONS

Our findings suggest that modifying Drp1 expression in T cells could serve as a potential therapeutic target for enhancing the antitumor immune response in future immunotherapies.

1-Pyrroline-5-carboxylate inhibit T cell glycolysis in prostate cancer microenvironment by SHP1/PKM2/LDHB axis

BACKGROUND

Our previous studies demonstrated that 1-Pyrroline-5-carboxylate (P5C) released by prostate cancer cells inhibits T cell proliferation and function by increasing SHP1 expression. We designed this study to further explore the influence of P5C on T cell metabolism, and produced an antibody for targeting P5C to restore the functions of T cells.

METHOD

We co-immunoprecipated SHP1 from T cells and analyzed the proteins that were bound to it using liquid chromatography mass spectrometry (LC/MS-MS). The influence of P5C on T cells metabolism was also detected by LC/MS-MS. Seahorse XF96 analyzer was further used to identify the effect of P5C on T cells glycolysis. We subsequently designed and produced an antibody for targeting P5C by monoclonal technique and verified its effectiveness to restore the function of T cells in vitro and in vivo.

RESULT

PKM2 and LDHB bind SHP1 in T cells, and P5C could increase the levels of p-PKM2 while having no effect on the levels of PKM2 and LDHB. We further found that P5C influences T cell energy metabolism and carbohydrate metabolism. P5C also inhibits the activity of PKM2 and decreases the content of intracellular lactic acid while increasing the activity of LDH. Using seahorse XF96 analyzer, we confirmed that P5C remarkably inhibits glycolysis in T cells. We produced an antibody for targeting P5C by monoclonal technique and verified that the antibody could oppose the influence of P5C to restore the process of glycolysis and function in T cells. Meanwhile, the antibody also inhibits the growth of prostate tumors in an animal model.

CONCLUSION

Our study revealed that P5C inhibits the process of glycolysis in T cells by targeting SHP1/PKM2/LDHB complexes. Moreover, it is important that the antibody for targeting P5C could restore the function of T cells and inhibit the growth of prostate tumors.

Metabolic reprogramming in the tumor microenvironment of liver cancer

The liver is essential for metabolic homeostasis. The onset of liver cancer is often accompanied by dysregulated liver function, leading to metabolic rearrangements. Overwhelming evidence has illustrated that dysregulated cellular metabolism can, in turn, promote anabolic growth and tumor propagation in a hostile microenvironment. In addition to supporting continuous tumor growth and survival, disrupted metabolic process also creates obstacles for the anticancer immune response and restrains durable clinical remission following immunotherapy. In this review, we elucidate the metabolic communication between liver cancer cells and their surrounding immune cells and discuss how metabolic reprogramming of liver cancer impacts the immune microenvironment and the efficacy of anticancer immunotherapy. We also describe the crucial role of the gut-liver axis in remodeling the metabolic crosstalk of immune surveillance and escape, highlighting novel therapeutic opportunities.

Examining Chronic Inflammation, Immune Metabolism, and T Cell Dysfunction in HIV Infection

Chronic Human Immunodeficiency Virus (HIV) infection remains a significant challenge to global public health. Despite advances in antiretroviral therapy (ART), which has transformed HIV infection from a fatal disease into a manageable chronic condition, a definitive cure remains elusive. One of the key features of HIV infection is chronic immune activation and inflammation, which are strongly associated with, and predictive of, HIV disease progression, even in patients successfully treated with suppressive ART. Chronic inflammation is characterized by persistent inflammation, immune cell metabolic dysregulation, and cellular exhaustion and dysfunction. This review aims to summarize current knowledge of the interplay between chronic inflammation, immune metabolism, and T cell dysfunction in HIV infection, and also discusses the use of humanized mice models to study HIV immune pathogenesis and develop novel therapeutic strategies.

PA suppresses antitumor immunity of T cells by disturbing mitochondrial activity through Akt/mTOR-mediated Ca2+ flux

Deciphering the mechanisms behind how T cells become exhausted and regulatory T cells (Tregs) differentiate in a tumor microenvironment (TME) will significantly benefit cancer immunotherapy. A common metabolic alteration feature in TME is lipid accumulation, associated with T cell exhaustion and Treg differentiation. However, the regulatory role of free fatty acids (FFA) on T cell antitumor immunity has yet to be clearly illustrated. Our study observed that palmitic acid (PA), the most abundant saturated FFA in mouse plasma, enhanced T cell exhaustion and Tregs population in TME and increased tumor growth. In contrast, oleic acid (OA), a monounsaturated FFA, rescued PA-induced T cell exhaustion, decreased Treg population, and ameliorated T cell antitumor immunity in an obese mouse model. Mechanistically, mitochondrial metabolic activity is critical in maintaining T cell function, which PA attenuated. PA-induced T cell exhaustion and Treg formation depended on CD36 and Akt/mTOR-mediated calcium signaling. The study described a new mechanism of PA-induced downregulation of antitumor immunity of T cells and the therapeutic potential behind its restoration by targeting PA.

Mitochondrial Transplantation promotes protective effector and memory CD4+ T cell response during Mycobacterium tuberculosis infection and diminishes exhaustion and senescence in elderly CD4+ T cells

Tuberculosis (TB), caused by the bacterium Mycobacterium tuberculosis (M.tb), remains a significant health concern worldwide, especially in populations with weakened or compromised immune systems, such as the elderly. Proper adaptive immune function, particularly a CD4+ T cell response, is central to host immunity against M.tb. Chronic infections, such as M.tb, as well as aging promote T cell exhaustion and senescence, which can impair immune control and promote progression to TB disease. Mitochondrial dysfunction contributes to T cell dysfunction, both in aging and chronic infections and diseases. Mitochondrial perturbations can disrupt cellular metabolism, enhance oxidative stress, and impair T-cell signaling and effector functions. This study examined the impact of mitochondrial transplantation (mito-transfer) on CD4+ T cell differentiation and function using aged mouse models and human CD4+ T cells from elderly individuals. Our study revealed that mito-transfer in naïve CD4+ T cells promoted the generation of protective effector and memory CD4+ T cells during M.tb infection in mice. Further, mito-transfer enhanced the function of elderly human T cells by increasing their mitochondrial mass and modulating cytokine production, which in turn reduced exhaustion and senescence cell markers. Our results suggest that mito-transfer could be a novel strategy to reestablish aged CD4+ T cell function, potentially improving immune responses in the elderly and chronic TB patients, with a broader implication for other diseases where mitochondrial dysfunction is linked to T cell exhaustion and senescence.

Radiotherapy-Triggered In Situ Tumor Vaccination Boosts Checkpoint Blockaded Immune Response via Antigen-Capturing Nanoadjuvants

In situ vaccination (ISV) formed with the aid of intratumorally injected adjuvants has shed bright light on enhancing the abscopal therapeutic effects of radiotherapy. However, the limited availability of antigens resulting from the radiotherapy-induced immunogenic cell death largely hampers the clinical outcome of ISV. To maximally utilize the radiotherapy-induced antigen, we herein developed a strategy by capturing the radiotherapy-induced antigen in situ with a nanoadjuvant comprised of CpG-loaded Fe3O4 nanoparticles. The highly efficient click reaction between the maleimide residue on the nanoadjuvant and sulfhydryl group on the antigen maximized the bioavailability of autoantigens and CpG adjuvant in vivo. Importantly, combined immune checkpoint blockade can reverse T cell exhaustion after treatment with radiotherapy-induced ISV, thereby largely suppressing the treated and distant tumor. Mechanistically, metabolomics reveals the intratumorally injected nanoadjuvants disrupt redox homeostasis in the tumor microenvironment, further inducing tumor ferroptosis after radiotherapy. Overall, the current study highlights the immense potential of the innovative antigen-capturing nanoadjuvants for synergistically enhancing the antitumor effect.

IL-10-expressing CAR T cells resist dysfunction and mediate durable clearance of solid tumors and metastases

The success of chimeric antigen receptor (CAR) T cell therapy in treating several hematopoietic malignancies has been difficult to replicate in solid tumors, in part because of T cell exhaustion and eventually dysfunction. To counter T cell dysfunction in the tumor microenvironment, we metabolically armored CAR T cells by engineering them to secrete interleukin-10 (IL-10). We show that IL-10 CAR T cells preserve intact mitochondrial structure and function in the tumor microenvironment and increase oxidative phosphorylation in a mitochondrial pyruvate carrier-dependent manner. IL-10 secretion promoted proliferation and effector function of CAR T cells, leading to complete regression of established solid tumors and metastatic cancers across several cancer types in syngeneic and xenograft mouse models, including colon cancer, breast cancer, melanoma and pancreatic cancer. IL-10 CAR T cells also induced stem cell-like memory responses in lymphoid organs that imparted durable protection against tumor rechallenge. Our results establish a generalizable approach to counter CAR T cell dysfunction through metabolic armoring, leading to solid tumor eradication and long-lasting immune protection.

Overexpression of AMPKγ2 increases AMPK signaling to augment human T cell metabolism and function

Cellular therapies are currently employed to treat a variety of disease processes. For T cell-based therapies, success often relies on the metabolic fitness of the T cell product, where cells with enhanced metabolic capacity demonstrate improved in vivo efficacy. AMP-activated protein kinase (AMPK) is a cellular energy sensor which combines environmental signals with cellular energy status to enforce efficient and flexible metabolic programming. We hypothesized that increasing AMPK activity in human T cells would augment their oxidative capacity, creating an ideal product for adoptive cellular therapies. Lentiviral transduction of the regulatory AMPKγ2 subunit stably enhanced intrinsic AMPK signaling and promoted mitochondrial respiration with increased basal oxygen consumption rates, higher maximal oxygen consumption rate, and augmented spare respiratory capacity. These changes were accompanied by increased proliferation and inflammatory cytokine production, particularly within restricted glucose environments. Introduction of AMPKγ2 into bulk CD4 T cells decreased RNA expression of canonical Th2 genes, including the cytokines interleukin (IL)-4 and IL-5, while introduction of AMPKγ2 into individual Th subsets universally favored proinflammatory cytokine production and a downregulation of IL-4 production in Th2 cells. When AMPKγ2 was overexpressed in regulatory T cells, both in vitro proliferation and suppressive capacity increased. Together, these data suggest that augmenting intrinsic AMPK signaling via overexpression of AMPKγ2 can improve the expansion and functional potential of human T cells for use in a variety of adoptive cellular therapies.

Hurdle or thruster: Glucose metabolism of T cells in anti-tumour immunity

Glucose metabolism is essential for the activation, differentiation and function of T cells and proper glucose metabolism is required to maintain effective T cell immunity. Dysregulation of glucose metabolism is a hallmark of cancer, and the tumour microenvironment (TME2) can create metabolic barriers in T cells that inhibit their anti-tumour immune function. Targeting glucose metabolism is a promising approach to improve the capacity of T cells in the TME. The efficacy of common immunotherapies, such as immune checkpoint inhibitors (ICIs3) and adoptive cell transfer (ACT4), can be limited by T-cell function, and the treatment itself can affect T-cell metabolism. Therefore, understanding the relationship between immunotherapy and T cell glucose metabolism helps to achieve more effective anti-tumour therapy. In this review, we provide an overview of T cell glucose metabolism and how T cell metabolic reprogramming in the TME regulates anti-tumour responses, briefly describe the metabolic patterns of T cells during ICI and ACT therapies, which suggest possible synergistic strategies.

De novo NAD+ synthesis contributes to CD8+ T cell metabolic fitness and antitumor function

The dysfunction and clonal constriction of tumor-infiltrating CD8+ T cells are accompanied by alterations in cellular metabolism; however, how the cell-intrinsic metabolic pathway specifies intratumoral CD8+ T cell features remains elusive. Here, we show that cell-autonomous generation of nicotinamide adenine dinucleotide (NAD+) via the kynurenine pathway (KP) contributes to the maintenance of intratumoral CD8+ T cell metabolic and functional fitness. De novo NAD+ synthesis is involved in CD8+ T cell metabolism and antitumor function. KP-derived NAD+ promotes PTEN deacetylation, thereby facilitating PTEN degradation and preventing PTEN-dependent metabolic defects. Importantly, impaired cell-autonomous NAD+ synthesis limits CD8+ T cell responses in human colorectal cancer samples. Our results reveal that KP-derived NAD+ regulates the CD8+ T cell metabolic and functional state by restricting PTEN activity and suggest that modulation of de novo NAD+ synthesis could restore CD8+ T cell metabolic fitness and antitumor function.

Implications of Senescent T Cells for Cancer Immunotherapy

T-cell senescence is thought to result from the age-related loss of the ability to mount effective responses to pathogens and tumor cells. In addition to aging, T-cell senescence is caused by repeated antigenic stimulation and chronic inflammation. Moreover, we demonstrated that T-cell senescence was induced by treatment with DNA-damaging chemotherapeutic agents. The characteristics of therapy-induced senescent T (TIS-T) cells and general senescent T cells are largely similar. Senescent T cells demonstrate an increase in the senescence-associated beta-galactosidase-positive population, cell cycle arrest, secretion of senescence-associated secretory phenotypic factors, and metabolic reprogramming. Furthermore, senescent T cells downregulate the expression of the co-stimulatory molecules CD27 and CD28 and upregulate natural killer cell-related molecules. Moreover, TIS-T cells showed increased PD-1 expression. However, the loss of proliferative capacity and decreased expression of co-stimulatory molecules associated with T-cell senescence cause a decrease in T-cell immunocompetence. In this review, we discuss the characteristics of senescent T-cells, including therapy-induced senescent T cells.

Re-"Formate" T-cell Antitumor Responses

SUMMARY

Rowe and colleagues discover that one-carbon (1C) metabolism rewiring occurs upon T-cell activation to support proliferation and cytolytic activity in CD8+ T cells and that supplementation of 1C donor formate rescues the dysfunctional T cells and their responsiveness to anti-PD-1 in selective tumor-infiltrated T-cell subsets. This finding represents an attractive strategy to overcome a metabolic vulnerability in the tumor microenvironment and improve the efficacy of immune checkpoint blockade. See related article by Rowe et al., p. 2566 (8).

Magnetic Metal-Organic Framework-Based Nanoplatform with Platelet Membrane Coating as a Synergistic Programmed Cell Death Protein 1 Inhibitor against Hepatocellular Carcinoma

Programmed cell death protein 1 (PD-1) inhibitors are the most common immune-checkpoint inhibitors and considered promising drugs for hepatocellular carcinoma (HCC). However, in clinical settings, they have a low objective response rate (15%-20%) for patients with HCC; this is because of the insufficient level and activity of tumor-infiltrating T lymphocytes (TILs). The combined administration of oxymatrine (Om) and astragaloside IV (As) can increase the levels of TILs by inhibiting the activation of cancer-associated fibroblasts (CAFs) and improve the activity of TILs by enhancing their mitochondrial function. In the present study, we constructed a magnetic metal-organic framework (MOF)-based nanoplatform with platelet membrane (Pm) coating (PmMN@Om&As) to simultaneously deliver Om and As into the HCC microenvironment. We observed that PmMN@Om&As exhibited a high total drug-loading capacity (33.77 wt %) and good immune escape. Furthermore, it can target HCC tissues in a magnetic field and exert long-lasting effects. The HCC microenvironment accelerated the disintegration of PmMN@Om&As and the release of Om&As, thereby increasing the level and activity of TILs by regulating CAFs and the mitochondrial function of TILs. In addition, the carrier could synergize with Om&As by enhancing the oxygen consumption rate and proton efflux rate of TILs, thereby upregulating the mitochondrial function of TILs. Combination therapy with PmMN@Om&As and α-PD-1 resulted in a tumor suppression rate of 84.15% and prolonged the survival time of mice. Our study provides a promising approach to improving the antitumor effect of immunotherapy in HCC.

Exploiting autophagy balance in T and NK cells as a new strategy to implement adoptive cell therapies

Autophagy is an essential cellular homeostasis pathway initiated by multiple stimuli ranging from nutrient deprivation to viral infection, playing a key role in human health and disease. At present, a growing number of evidence suggests a role of autophagy as a primitive innate immune form of defense for eukaryotic cells, interacting with components of innate immune signaling pathways and regulating thymic selection, antigen presentation, cytokine production and T/NK cell homeostasis. In cancer, autophagy is intimately involved in the immunological control of tumor progression and response to therapy. However, very little is known about the role and impact of autophagy in T and NK cells, the main players in the active fight against infections and tumors. Important questions are emerging: what role does autophagy play on T/NK cells? Could its modulation lead to any advantages? Could specific targeting of autophagy on tumor cells (blocking) and T/NK cells (activation) be a new intervention strategy? In this review, we debate preclinical studies that have identified autophagy as a key regulator of immune responses by modulating the functions of different immune cells and discuss the redundancy or diversity among the subpopulations of both T and NK cells in physiologic context and in cancer.

The role of mitochondria-related lncRNAs in characterizing the immune landscape and supervising the prognosis of osteosarcoma

Mitochondrial damage is related to the functional properties of immune cells as well as to tumorigenesis and progression. Nevertheless, there is an absence concerning the systematic evaluation of mitochondria-associated lncRNAs (MALs) in the immune profile and tumor microenvironment of osteosarcoma patients. Based on transcriptomic and clinicopathological data from the TARGET database, MAL-related patterns were ascertained by consistent clustering, and gene set variation analysis of the different patterns was completed. Next, a MAL-derived scoring system was created using Cox and LASSO regression analyses and validated by Kaplan-Meier and ROC curves. The GSEA, ESTIMATE, and CIBERSORT algorithms were utilized to characterize the immune status and underlying biological functions in the different MAL score groups. MAL-derived risk scores were well stabilized and outperformed traditional clinicopathological features to reliably predict 5-year survival in osteosarcoma cohorts. Moreover, patients with increased MAL scores were observed to suffer from poorer prognosis, higher tumor purity, and an immunosuppressive microenvironment. Based on estimated half-maximal inhibitory concentrations, the low-MAL score group benefited more from gemcitabine and docetaxel, and less from thapsigargin and sunitinib compared to the high-MAL score group. Pan-cancer analysis demonstrated that six hub MALs were strongly correlated with clinical outcomes, immune subtypes, and tumor stemness indices in various common cancers. Finally, we verified the expression patterns of hub MALs in osteosarcoma with qRT-PCR. In summary, we identified the crosstalk between prognostic MALs and tumor-infiltrating immune cells in osteosarcoma, providing a potential strategy to ameliorate clinical stratification management.

CD26 CAR-T cells have attenuated mitochondrial and glycolytic metabolic profiling

BACKGROUND

Multiple targets of chimeric antigen receptor T cells (CAR-T cells) are shared expressed by tumor cells and T cells, these self-antigens may stimulate CAR-T cells continuously during the expansion. Persistent exposure to antigens is considered to cause metabolic reprogramming of T cells and the metabolic profiling is critical in determining the cell fate and effector function of CAR-T cells. However, whether the stimulation of self-antigens during CAR-T cell generation could remodel the metabolic profiling is unclear. In this study, we aim to investigate the metabolic characteristics of CD26 CAR-T cells, which expressed CD26 antigens themselves.

METHODS

The mitochondrial biogenesis of CD26 and CD19 CAR-T cells during expansion was evaluated by the mitochondrial content, mitochondrial DNA copy numbers and genes involved in mitochondrial regulation. The metabolic profiling was investigated by the ATP production, mitochondrial quality and the expression of metabolism-related genes. Furthermore, we assessed the phenotypes of CAR-T cells through memory-related markers.

RESULTS

We reported that CD26 CAR-T cells had elevated mitochondrial biogenesis, ATP production and oxidative phosphorylation at early expansion stage. However, the mitochondrial biogenesis, mitochondrial quality, oxidative phosphorylation and glycolytic activity were all weakened at later expansion stage. On the contrary, CD19 CAR-T cells did not exhibit such characteristics.

CONCLUSION

CD26 CAR-T cells showed distinctive metabolic profiling during expansion that was extremely unfavorable to cell persistence and function. These findings may provide new insights for the optimization of CD26 CAR-T cells in terms of metabolism.

The coenzyme A precursor pantethine enhances antitumor immunity in sarcoma

The tumor microenvironment is a dynamic network of stromal, cancer, and immune cells that interact and compete for resources. We have previously identified the Vanin1 pathway as a tumor suppressor of sarcoma development via vitamin B5 and coenzyme A regeneration. Using an aggressive sarcoma cell line that lacks Vnn1 expression, we showed that the administration of pantethine, a vitamin B5 precursor, attenuates tumor growth in immunocompetent but not nude mice. Pantethine boosts antitumor immunity, including the polarization of myeloid and dendritic cells towards enhanced IFNγ-driven antigen presentation pathways and improved the development of hypermetabolic effector CD8+ T cells endowed with potential antitumor activity. At later stages of treatment, the effect of pantethine was limited by the development of immune cell exhaustion. Nevertheless, its activity was comparable with that of anti-PD1 treatment in sensitive tumors. In humans, VNN1 expression correlates with improved survival and immune cell infiltration in soft-tissue sarcomas, but not in osteosarcomas. Pantethine could be a potential therapeutic immunoadjuvant for the development of antitumor immunity.

The immunometabolic ecosystem in cancer

Our increased understanding of how key metabolic pathways are activated and regulated in malignant cells has identified metabolic vulnerabilities of cancers. Translating this insight to the clinics, however, has proved challenging. Roadblocks limiting efficacy of drugs targeting cancer metabolism may lie in the nature of the metabolic ecosystem of tumors. The exchange of metabolites and growth factors between cancer cells and nonmalignant tumor-resident cells is essential for tumor growth and evolution, as well as the development of an immunosuppressive microenvironment. In this Review, we will examine the metabolic interplay between tumor-resident cells and how targeted inhibition of specific metabolic enzymes in malignant cells could elicit pro-tumorigenic effects in non-transformed tumor-resident cells and inhibit the function of tumor-specific T cells. To improve the efficacy of metabolism-targeted anticancer strategies, a holistic approach that considers the effect of metabolic inhibitors on major tumor-resident cell populations is needed.

Salvage therapy expands highly cytotoxic and metabolically fit resilient CD8+ T cells via ME1 up-regulation

Patients with advanced cancers who either do not experience initial response to or progress while on immune checkpoint inhibitors (ICIs) receive salvage radiotherapy to reduce tumor burden and tumor-related symptoms. Occasionally, some patients experience substantial global tumor regression with a rebound of cytotoxic CD8+ T cells. We have termed the rebound of cytotoxic CD8+ T cells in response to salvage therapy as T cell resilience and examined the underlying mechanisms of resilience. Resilient T cells are enriched for CX3CR1+ CD8+ T cells with low mitochondrial membrane potential, accumulate less reactive oxygen species (ROS), and express more malic enzyme 1 (ME1). ME1 overexpression enhanced the cytotoxicity and expansion of effector CD8+ T cells partially via the type I interferon pathway. ME1 also increased mitochondrial respiration while maintaining the redox state balance. ME1 increased the cytotoxicity of peripheral lymphocytes from patients with advanced cancers. Thus, preserved resilient T cells in patients rebound after salvage therapy and ME1 enhances their resiliency.

BCL11B and the NuRD complex cooperatively guard T-cell fate and inhibit OPA1-mediated mitochondrial fusion in T cells

The nucleosome remodeling and histone deacetylase (NuRD) complex physically associates with BCL11B to regulate murine T-cell development. However, the function of NuRD complex in mature T cells remains unclear. Here, we characterize the fate and metabolism of human T cells in which key subunits of the NuRD complex or BCL11B are ablated. BCL11B and the NuRD complex bind to each other and repress natural killer (NK)-cell fate in T cells. In addition, T cells upregulate the NK cell-associated receptors and transcription factors, lyse NK-cell targets, and are reprogrammed into NK-like cells (ITNKs) upon deletion of MTA2, MBD2, CHD4, or BCL11B. ITNKs increase OPA1 expression and exhibit characteristically elongated mitochondria with augmented oxidative phosphorylation (OXPHOS) activity. OPA1-mediated elevated OXPHOS enhances cellular acetyl-CoA levels, thereby promoting the reprogramming efficiency and antitumor effects of ITNKs via regulating H3K27 acetylation at specific targets. In conclusion, our findings demonstrate that the NuRD complex and BCL11B cooperatively maintain T-cell fate directly by repressing NK cell-associated transcription and indirectly through a metabolic-epigenetic axis, providing strategies to improve the reprogramming efficiency and antitumor effects of ITNKs.

Lactate activates the mitochondrial electron transport chain independently of its metabolism

Lactate has long been considered a cellular waste product. However, we found that as extracellular lactate accumulates, it also enters the mitochondrial matrix and stimulates mitochondrial electron transport chain (ETC) activity. The resulting increase in mitochondrial ATP synthesis suppresses glycolysis and increases the utilization of pyruvate and/or alternative respiratory substrates. The ability of lactate to increase oxidative phosphorylation does not depend on its metabolism. Both L- and D-lactate are effective at enhancing ETC activity and suppressing glycolysis. Furthermore, the selective induction of mitochondrial oxidative phosphorylation by unmetabolized D-lactate reversibly suppressed aerobic glycolysis in both cancer cell lines and proliferating primary cells in an ATP-dependent manner and enabled cell growth on respiratory-dependent bioenergetic substrates. In primary T cells, D-lactate enhanced cell proliferation and effector function. Together, these findings demonstrate that lactate is a critical regulator of the ability of mitochondrial oxidative phosphorylation to suppress glucose fermentation.

Stem-like exhausted and memory CD8+ T cells in cancer

T cells can acquire a broad spectrum of differentiation states following activation. At the extreme ends of this continuum are short-lived cells equipped with effector machinery and more quiescent, long-lived cells with heightened proliferative potential and stem cell-like developmental plasticity. The latter encompass stem-like exhausted T cells and memory T cells, both of which have recently emerged as key determinants of cancer immunity and response to immunotherapy. Here, we discuss key similarities and differences in the regulation and function of stem-like exhausted CD8+ T cells and memory CD8+ T cells, and consider their context-specific contributions to protective immunity in diverse outcomes of cancer, including tumour escape, long-term control and eradication. Finally, we emphasize how recent advances in the understanding of the molecular regulation of stem-like exhausted T cells and memory T cells are being explored for clinical benefit in cancer immunotherapies such as checkpoint inhibition, adoptive cell therapy and vaccination.

The role and participation of immune cells in the endometrial tumor microenvironment

The tumor microenvironment is surrounded by blood vessels and consists of malignant, non-malignant, and immune cells, as well as signalling molecules, which primarily affect the therapeutic response and curative effects of drugs in clinical studies. Tumor-infiltrating immune cells participate in tumor progression, impact anticancer therapy, and eventually lead to the development of immune tolerance. Immunotherapy is evolving as a promising therapeutic intervention to stimulate and activate the immune system to suppress cancer cell growth. Endometrial cancer (EC) is an immunogenic disease, and in recent years, immunotherapy has shown benefit in the treatment of recurrent and advanced EC. This review discusses the key molecular pathways associated with the intra-tumoral immune response and the involvement of circulatory signalling molecules. Specific immunologic signatures in EC which offer targets for immunomodulating agents, are also discussed. We have summarized the available literature in support of using immunotherapy in EC. Lastly, we have also discussed ongoing clinical trials that may offer additional promising immunotherapy options in the future. The manuscript also explored innovative approaches for screening and identifying effective drugs, and to reduce the financial burdens for the development of personalized treatment strategies. Collectively, we aim to provide a comprehensive review of the role of immune cells and the tumor microenvironment in the development, progression, and treatment of EC.

T Lymphocyte Metabolic Features and Techniques to Modulate Them

T cells demonstrate high degree of complexity and broad range of functions, which distinguish them from other immune cells. Throughout their lifetime, T lymphocytes experience several functional states: quiescence, activation, proliferation, differentiation, performance of effector and regulatory functions, memory formation, and apoptosis. Metabolism supports all functions of T cells, providing lymphocytes with energy, biosynthetic substrates, and signaling molecules. Therefore, T cells usually restructure their metabolism as they transition from one functional state to another. Strong association between the metabolism and T cell functions implies that the immune response can be controlled by manipulating metabolic processes within T lymphocytes. This review aims to highlight the main metabolic adaptations necessary for the T cell function, as well as the recent progress in techniques to modulate metabolic features of lymphocytes.