High Glucose Enhances Cytotoxic T Lymphocyte-Mediated Cytotoxicity

Disruption of glucose homeostasis by bacterial infection orchestrates host innate immunity through NAD+/NADH balance

Metabolic reprogramming is crucial for activating innate immunity in macrophages, and the accumulation of immunometabolites is essential for effective defense against infection. The NAD+/NADH (ratio of nicotinamide adenine dinucleotide and its reduced counterpart) redox couple serves as a critical node that integrates metabolic pathways and signaling events, but how this metabolite couple engages macrophage activation remains unclear. Here, we show that the NAD+/NADH ratio serves as a molecular signal that regulates proinflammatory responses and type I interferon (IFN) responses divergently. Salmonella Typhimurium infection leads to a decreased NAD+/NADH ratio by inducing the accumulation of NADH. Further investigation shows that an increased NAD+/NADH ratio correlates with attenuated proinflammatory responses and enhanced type I IFN responses. Conversely, a decreased NAD+/NADH ratio is linked to intensified proinflammatory responses and restrained type I IFN responses. These results show that the NAD+/NADH ratio is an essential cell-intrinsic factor that orchestrates innate immunity, which enhances our understanding of how metabolites fine-tune innate immunity.

Genetically engineering glycolysis in T cells increases their antitumor function

BACKGROUND

T cells play a central role in the antitumor response. However, they often face numerous hurdles in the tumor microenvironment, including the scarcity of available essential metabolites such as glucose and amino acids. Moreover, cancer cells can monopolize these resources to thrive and proliferate by upregulating metabolite transporters and maintaining a high metabolic rate, thereby outcompeting T cells.

METHODS

Herein, we sought to improve T-cell antitumor function in the tumor vicinity by enhancing their glycolytic capacity to better compete with tumor cells. To achieve this, we engineered human T cells to express a key glycolysis enzyme, phosphofructokinase, in conjunction with Glucose transporter 3, a glucose transporter. We co-expressed these, along with tumor-specific chimeric antigen or T-cell receptors.

RESULTS

Engineered cells demonstrated an increased cytokine secretion and upregulation of T-cell activation markers compared with control cells. Moreover, they displayed superior glycolytic capacity, which translated into an improved in vivo therapeutic potential in a xenograft model of human tumors.

CONCLUSION

In summary, these findings support the implementation of T-cell metabolic engineering to enhance the efficacy of cellular immunotherapies for cancer.

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.

Paclitaxel combined with Compound K inducing pyroptosis of non-small cell lung cancer cells by regulating Treg/Th17 balance

BACKGROUND

Immune checkpoint inhibitors, which have attracted much attention in recent years, have achieved good efficacy, but their use is limited by the high incidence of acquired drug resistance. Therefore, there is an urgent need to develop new immunotherapy drugs. Compound taxus chinensis capsule (CTC) is an oral paclitaxel compound drug, clinical results showed it can change the number of regulatory T cells and T helper cell 17 in peripheral blood. Regulating the balance between regulatory T cells and T helper cell 17 is considered to be an effective anticancer strategy. Paclitaxel and ginsenoside metabolite compound K are the main immunomodulatory components, it is not clear that paclitaxel combined with compound K can inhibit tumor development by regulating the balance between regulatory T cell and T helper cell 17.

METHODS

MTT, EdU proliferation and plate colony formation assay were used to determine the concentration of paclitaxel and compound K. AnnexinV-FITC/PI staining, ELISA, Western Blot assay, Flow Cytometry and Immunofluorescence were used to investigate the effect of paclitaxel combined with compound K on Lewis cell cultured alone or co-cultured with splenic lymphocyte. Finally, transplanted tumor C57BL/6 mice model was constructed to investigate the anti-cancer effect in vivo.

RESULTS

According to the results of MTT, EdU proliferation and plate colony formation assay, paclitaxel (10 nM) and compound K (60 μM) was used to explore the mechanism. The results of Flow Cytometry demonstrated that paclitaxel combined with compound K increased the number of T helper cell 17 and decreased the number of regulatory T cells, which induced pyroptosis of cancer cells. The balance was mediated by the JAK-STAT pathway according to the results of Western Blot and Immunofluorescence. Finally, the in vivo results showed that paclitaxel combined with compound K significantly inhibit the progression of lung cancer.

CONCLUSIONS

In this study, we found that paclitaxel combined with compound K can activate CD8+ T cells and induce pyroptosis of tumor cells by regulating the balance between regulatory T cells and T helper cell 17. These results demonstrated that this is a feasible treatment strategy for lung cancer.

Inflammageing mediated by cytotoxic lymphocytes is associated with diabetes duration

AIMS

Inflammageing, the age-related systemic increase of proinflammatory factors, has been linked to the development of cardiovascular disease, chronic kidney disease and cancer in the elderly. Chronic inflammation is believed to be a causative factor in the development of diabetic complications. However, exactly how type 2 diabetes impacts the inflammatory state of the immune system is incompletely characterised.

METHODS

Blood collection and anthropometric measurements were performed in patients with type 2 diabetes (n = 49) and control subjects (n = 30). The phenotype, proliferation capacity and cytokine production by cytotoxic lymphocytes were analysed using multiparametric flow cytometry.

RESULTS

Type 2 diabetes did not impact the phenotype or proliferation of the investigated cells. However, we observed a significantly increased production of tumour necrosis factor-α by CD8+ T cells and Granzyme B by natural killer cells and γδ T cells compared to controls. Hyperresponsiveness of cytotoxic blood lymphocytes did not correlate with glycaemia or body mass index, but instead was associated with older age and longer diabetes duration.

CONCLUSIONS

Type 2 diabetes is associated with an increased pro-inflammatory potential of cytotoxic blood lymphocytes correlating with age and diabetes duration. Further research is necessary to explore potential benefits of diabetes medications in reverting this effect.

Effects of altered glycolysis levels on CD8+ T cell activation and function

CD8+ T cells are an important component of the body's adaptive immune response. During viral or intracellular bacterial infections, CD8+ T cells are rapidly activated and differentiated to exert their immune function by producing cytokines. Alterations in the glycolysis of CD8+ T cells have an important effect on their activation and function, while glycolysis is important for CD8+ T cell functional failure and recovery. This paper summarizes the importance of CD8+ T cell glycolysis in the immune system. We discuss the link between glycolysis and CD8+ T cell activation, differentiation, and proliferation, and the effect of altered glycolysis on CD8+ T cell function. In addition, potential molecular targets to enhance and restore the immune function of CD8+ T cells by affecting glycolysis and the link between glycolysis and CD8+ T cell senescence are summarized. This review provides new insights into the relationship between glycolysis and CD8+ T cell function, and proposes novel strategies for immunotherapy by targeting glycolysis.

Heterozygous OT-I mice reveal that antigen-specific CD8+ T cells shift from apoptotic to necrotic killers in the elderly

Numerous alterations in CD8⁺ T cells contribute to impaired immune responses in elderly individuals. However, the discrimination between cell-intrinsic dysfunctions and microenvironmental changes is challenging. TCR transgenic OT-I mice are utilized to investigate CD8⁺ T-cell immunity, but their immunodeficient phenotype hampers their use especially in aging. Here, we demonstrate that using a heterozygous OT-I model minimizes the current limitations and provides a valuable tool to assess antigen-specific T-cell responses even at old age. We analyzed phenotypic and functional characteristics of CD8⁺ T cells from OT-I^+/+ and OT-I^+/- mice to prove the applicability of the heterozygous system. Our data reveal that OVA-activated CD8⁺ T cells from adult OT-I^+/- mice proliferate, differentiate, and exert cytolytic activity equally to their homozygous counterparts. Moreover, common age-related alterations in CD8⁺ T cells, including naive T-cell deterioration and decreased proliferative capacity, also occur in elderly OT-I^+/- mice, indicating the wide range of applications for in vivo and in vitro aging studies. We used the OT-I^+/- model to investigate cell-intrinsic alterations affecting the cytotoxic behavior of aged CD8⁺ T cells after antigen-specific in vitro activation. Time-resolved analysis of antigen-directed target cell lysis confirmed previous observations that the cytotoxic capacity of CD8⁺ T cells increases with age. Surprisingly, detailed single cell analysis revealed that transcriptional upregulation of perforin in aged CD8⁺ T cells shifts the mode of target cell death from granzyme-mediated apoptosis to rapid induction of necrosis. This unexpected capability might be beneficial or detrimental for the aging host and requires detailed evaluation.

Manipulating T-cell metabolism to enhance immunotherapy in solid tumor

Cellular metabolism is not only essential for tumor cells to sustain their rapid growth and proliferation, but also crucial to maintain T cell fitness and robust immunity. Dysregulated metabolism has been recognized as a hallmark of cancer, which provides survival advantages for tumor cells under stress conditions. Also, emerging evidence suggests that metabolic reprogramming impacts the activation, differentiation, function, and exhaustion of T cells. Normal stimulation of resting T cells promotes the conversion of catabolic and oxidative metabolism to aerobic glycolysis in effector T cells, and subsequently back to oxidative metabolism in memory T cells. These metabolic transitions profoundly affect the trajectories of T-cell differentiation and fate. However, these metabolic events of T cells could be dysregulated by their interplays with tumor or the tumor microenvironment (TME). Importantly, metabolic competition in the tumor ecosystem is a new mechanism resulting in strong suppression of effector T cells. It is appreciated that targeting metabolic reprogramming is a promising way to disrupt the hypermetabolic state of tumor cells and enhance the capacity of immune cells to obtain nutrients. Furthermore, immunotherapies, such as immune checkpoint inhibitor (ICI), adoptive cell therapy (ACT), and oncolytic virus (OV) therapy, have significantly refashioned the clinical management of solid tumors, they are not sufficiently effective for all patients. Understanding how immunotherapy affects T cell metabolism provides a bright avenue to better modulate T cell anti-tumor response. In this review, we provide an overview of the cellular metabolism of tumor and T cells, provide evidence on their dynamic interaction, highlight how metabolic reprogramming of tumor and T cells regulate the anti-tumor responses, describe T cell metabolic patterns in the context of ICI, ACT, and OV, and propose hypothetical combination strategies to favor potent T cell functionality.

Reprogramming T-Cell Metabolism for Better Anti-Tumor Immunity

T cells play central roles in the anti-tumor immunity, whose activation and differentiation are profoundly regulated by intrinsic metabolic reprogramming. Emerging evidence has revealed that metabolic processes of T cells are generally altered by tumor cells or tumor released factors, leading to crippled anti-tumor immunity. Therefore, better understanding of T cell metabolic mechanism is crucial in developing the next generation of T cell-based anti-tumor immunotherapeutics. In this review, we discuss how metabolic pathways affect T cells to exert their anti-tumor effects and how to remodel the metabolic programs to improve T cell-mediated anti-tumor immune responses. We emphasize that glycolysis, carboxylic acid cycle, fatty acid oxidation, cholesterol metabolism, amino acid metabolism, and nucleotide metabolism work together to tune tumor-reactive T-cell activation and proliferation.

Unspecific CTL Killing Is Enhanced by High Glucose via TNF-Related Apoptosis-Inducing Ligand

TNF-related apoptosis inducing ligand (TRAIL) is expressed on cytotoxic T lymphocytes (CTLs) and TRAIL is linked to progression of diabetes. However, the impact of high glucose on TRAIL expression and its related killing function in CTLs still remains largely elusive. Here, we report that TRAIL is substantially up-regulated in CTLs in environments with high glucose (HG) both in vitro and in vivo. Non-mitochondrial reactive oxygen species, NFκB and PI3K/Akt are essential in HG-induced TRAIL upregulation in CTLs. TRAIL^high CTLs induce apoptosis of pancreatic beta cell line 1.4E7. Treatment with metformin and vitamin D reduces HG-enhanced expression of TRAIL in CTLs and coherently protects 1.4E7 cells from TRAIL-mediated apoptosis. Our work suggests that HG-induced TRAIL^high CTLs might contribute to the destruction of pancreatic beta cells in a hyperglycemia condition.