Competition for nutrients and its role in controlling immune responses

Glutaminolysis and α-ketoglutarate-stimulated KCa3.1 expression contribute to β-adrenoceptor activation-induced myocardial fibrosis in mice

Heart failure is associated with myocardial fibrosis, a pivotal histopathological feature arising from β-adrenergic receptor (β-AR) stimulation through sympathetic nervous system activation. Augmented glutaminolysis with increased bioavailability of α-ketoglutarate (α-KG) is suggested to contribute to fibrogenesis and changes in cellular gene expression. KCa3.1 is a calcium-activated potassium channel expressed in fibroblasts and has been implicated in mediating fibrosis, yet the putative interactions between glutaminolysis and KCa3.1 in β-AR-mediated cardiac fibrosis remain poorly understood. Here, we performed a series of in vitro and in vivo experiments to investigate how α-KG might influence the expression of KCa3.1 in the context of experimental myocardial fibrosis driven by β-AR activation. In cultured adult mouse cardiac fibroblasts, α-KG exposure resulted in the upregulation of KCa3.1 mRNA and protein levels that were commensurate with the dose and duration of exposure, and also led to increased KCa3.1 channel currents. Exposure to α-KG led to a significant decrease in levels of histone methylation (H3K27me3) within the KCa3.1 promoter, a decrease in the association of the transcription repressor REST from this site, as well as an enrichment of transcription activator AP-1 binding. The exacerbated fibrotic signaling induced by α-KG in cultured fibroblasts was suppressed by functional inhibition of KCa3.1 or by genetic knockdown of Kcnn4. Moreover, β-AR activation by isoproterenol significantly augmented glutaminolysis mediated by glutaminase 1 (GLS1) and significantly increased α-KG levels detected in the supernatant of cultured fibroblasts and cardiomyocytes. In addition, isoproterenol-induced KCa3.1 expression in fibroblasts was curtailed by treatment with the GLS1 inhibitor CB-839, or by GLS1 gene knockdown, or by treatment with the selective β2-AR antagonist, ICI118551. In mouse models of established cardiac fibrosis evoked by isoproterenol-stimulation or β2-AR overexpression, treatment with CB-839 for 4 weeks suppressed the phenotypic features of fibrosis, and this was associated with a decline in α-KG tissue content, a lack of histone demethylation at the KCa3.1 promoter, as well as suppression of KCa3.1 expression. Taken together, our study demonstrates for the first time that glutaminolysis contributes to β-AR activation-induced myocardial fibrosis via α-KG-stimulated KCa3.1 expression. We anticipate that treatments which target the β-AR/GLS1/α-KG/KCa3.1 signaling pathway might be effective for cardiac fibrosis.

The suppressive role of GLS in radiosensitivity and irradiation-induced immune response in LUAD: integrating bioinformatics and experimental insights

Background

Radiotherapy elicits immune activation, thereby synergistically enhancing systemic tumor control when combined with immunotherapy. Glutaminase (GLS), a key enzyme for glutamine metabolism, has been found to regulate glutamine availability within tumor microenvironment (TME). However, the precise mechanisms through which GLS modulates radiosensitivity and irradiation-induced immune responses in lung adenocarcinoma (LUAD) and its clinical value remain to be fully elucidated.

Methods

We employed bulk RNA-seq and single-cell transcriptomics to explore the role of GLS expression in radiosensitivity and immune infiltration. The bioinformatic results were validated by in vitro and in vivo experiments. Co-culture assays and flow cytometry were used to validate the impact of GLS expression on CD8+ T cell activation and cytotoxicity. Moreover, a GLS-DSBr (double strand break repair) prognostic model was developed using machine learning with data from 2,066 LUAD patients.

Results

In vitro and in vivo experiments demonstrated that GLS silence inhibited DSB repair and promoted ferroptosis, therefore enhancing radiosensitivity. Single-cell and spatial transcriptomics revealed the immunomodulatory effects of GLS expression in the TME. Further, Co-culture assays and flow cytometry experiments indicated that silencing GLS in LUAD cells potentiated the activation and cytotoxicity of CD8+ T cells in the context of radiotherapy. The GLS-DSBr model demonstrated robust predictive performance for overall survival, as well as the efficacy of radiotherapy and immunotherapy in LUAD. The applicability of GLS-DSBr model was further validated through pan-cancer analysis.

Conclusion

In the contexts of radiotherapy, GLS downregulation exerts dual regulatory effects by modulating ferroptosis and remodeling the immune landscapes, particularly enhancing CD8+ T cell cytotoxicity. Our work suggests that strategies preferentially targeting GLS in tumor cells may represent promising and translatable therapeutic approaches to promote antitumor efficacy of radiotherapy plus immune checkpoint blockade in LUAD patients. Furthermore, the established GLS-DSBr model serves as a robust predictive tool for prognosis and effects of radiotherapy and immunotherapy, which assists personalized treatment optimization in LUAD.

Macrophages recycle phagocytosed bacteria to fuel immunometabolic responses

Macrophages specialize in phagocytosis, a cellular process that eliminates extracellular matter, including microorganisms, through internalization and degradation1,2. Despite the critical role of phagocytosis during bacterial infection, the fate of phagocytosed microbial cargo and its impact on the host cell are poorly understood. In this study, we show that ingested bacteria constitute an alternative nutrient source that skews immunometabolic host responses. By tracing stable isotope-labelled bacteria, we found that phagolysosomal degradation of bacteria provides carbon atoms and amino acids that are recycled into various metabolic pathways, including glutathione and itaconate biosynthesis, and satisfies the bioenergetic needs of macrophages. Metabolic recycling of microbially derived nutrients is regulated by the nutrient-sensing mechanistic target of rapamycin complex C1 and is intricately tied to microbial viability. Dead bacteria, as opposed to live bacteria, are enriched in cyclic adenosine monophosphate, sustain the cellular adenosine monophosphate pool and subsequently activate adenosine monophosphate protein kinase to inhibit the mechanistic target of rapamycin complex C1. Consequently, killed bacteria strongly fuel metabolic recycling and support macrophage survival but elicit decreased reactive oxygen species production and reduced interleukin-1β secretion compared to viable bacteria. These results provide a new insight into the fate of engulfed microorganisms and highlight a microbial viability-associated metabolite that triggers host metabolic and immune responses. Our findings hold promise for shaping immunometabolic intervention for various immune-related pathologies.

Lipid Metabolism and Immune Function: Chemical Tools for Insights into T-Cell Biology

Lipids are essential biomolecules playing critical roles in cellular processes, including energy storage, membrane structure, and signaling. This review highlights the chemical tools that have been developed to study the role of lipid metabolism in immune function, focusing on T-cell biology. Fatty acids (FAs), as core lipid components, influence immune responses through structural, signaling, and metabolic roles. Recent studies reveal how specific FAs modulate T-cell activation, proliferation, and function, with implications for regulatory and effector subsets. Emerging tools, such as fluorescence-based lipids and click chemistry, enable precise tracking of lipid uptake and metabolism at the single-cell level, addressing limitations of traditional bulk methods. Advances in metabolomics and proteomics offer further insights into lipid-mediated immune regulation. Understanding these mechanisms provides opportunities to target lipid metabolism in therapeutic strategies for cancer and other immune-related diseases. The integration of lipidomic technologies into immunology uncovers novel perspectives on how lipids shape immune responses at cellular and molecular scales.

The Intestinal Macrophage-Intestinal Stem Cell Axis in Inflammatory Bowel Diseases: From Pathogenesis to Therapy

The gut plays a crucial role in digestion and immunity, so its balance is essential to overall health. This balance relies on dynamic interactions between intestinal epithelial cells, immune cells, and crypt stem cells. Inflammatory bowel disease (IBD), which consists of ulcerative colitis and Crohn's disease, is a chronic relapsing inflammatory disease of the gastrointestinal tract closely related to immune dysfunction. Stem cells, known for their ability to self-renew and differentiate, play an important role in repairing damaged intestinal epithelium and maintaining homeostasis in vivo. Macrophages are key gatekeepers of intestinal immune homeostasis and have a significant impact on IBD. Current research has focused on the link between epithelial cells and stem cells, but interactions with macrophages, which have been recognized as attractive targets for the development of new therapeutic approaches to disease, have been less explored. Recently, the developing field of immunometabolism has reinforced that metabolic reprogramming is a key determinant of macrophage function and subsequent disease progression. The aim of this review is to explore the role of the macrophage-stem cell axis in the maintenance of intestinal homeostasis and to summarize potential approaches to treating IBD by manipulating the cellular metabolism of macrophages, as well as the main opportunities and challenges faced. In summary, our overview provides a framework for understanding the critical role of macrophage immunometabolism in maintaining gut health and potential therapeutic targets.

Immunometabolic analysis of primary murine group 2 innate lymphoid cells: a robust step-by-step approach

Group 2 Innate Lymphoid Cells (ILC2s) have recently been shown to exert key regulatory functions in both innate and adaptive immune response networks that drive the establishment and progression of type 2 immunity. Although mainly tissue resident, ILC2s and their crosstalk within tissue microenvironments influence metabolism at both the local and systemic levels. In turn, the energetic demand and metabolic status within these systems shape the diverse phenotypes and effector functions of ILC2s. Deciphering these metabolic networks in ILC2s is therefore essential in understanding their various roles in health as well as their associated pathophysiologies. Here we detail a framework of experimental approaches to study key immunometabolic states of primary murine ILC2s and link them to unique phenotypes and their corresponding functionality. Utilizing flow cytometry, Single Cell ENergetic metabolism by profilIng Translation inHibition (SCENITH), and the Seahorse platform we provide a framework that allows in-depth analysis of cellular bioenergetic states to determine the immunometabolic wiring of ILC2s. Connecting immunometabolic states and networks to ILC2 phenotypes and effector functions with this method will allow future in-depth studies to assess the potential of novel pharmaceutics in altering ILC2 functionality in clinical settings.

PLOD3 as a novel oncogene in prognostic and immune infiltration risk model based on multi-machine learning in cervical cancer

Cervical carcinoma (CC) remains a significant global health issue despite advancements in screening and treatment. To improve prognostic accuracy and therapeutic strategies, we developed a multi-machine learning prognostic model based on metabolic-associated genes. This study integrated genomic, transcriptomic, and spatial data from multiple databases to identify key metabolic genes with a causal relationship to CC. We identified 112 key metabolic genes, which were used to construct and validate a prognostic model through various machine learning algorithms. GO and KEGG enrichment analysis revealed the MAPK cascade plays a crucial role in metabolic processes. To pinpoint key metabolic genes, we constructed WGCNA and extracted 337 key genes. Supervised principal component analysis and random survival forests were incorporated into the final model, which showed strong predictive ability in classifying patients. Furthermore, the model demonstrated notable variations in immune cell infiltration among risk categories, which shown regulatory T cells may be involved in immune suppression, and natural killer cells might have a limited effect in tumor clearance. Spatial transcriptomics and single-cell analyses further validated the model, uncovering tumor heterogeneity and distinct intercellular communication patterns associated with different risk levels. The functional experiment results indicated that down expression of PLOD3 could suppress the proliferation of CC cell. In this study, offer a precision medicine methods for predicting patient outcomes as well as fresh insights into the metabolic foundations, which may contribute to the prognosis and immunotherapy of CC. Additionally, we discovered PLOD3 to be a novel oncogene in CC. These findings imply that this model may be applied to assess prognostic risk and identify potential therapeutic targets for CC patients.

Sweet regulation - The emerging immunoregulatory roles of hexoses

BACKGROUND

It is widely acknowledged that dietary habits have profound impacts on human health and diseases. As the most important sweeteners and energy sources in human diets, hexoses take part in a broad range of physiopathological processes. In recent years, emerging evidence has uncovered the crucial roles of hexoses, such as glucose, fructose, mannose, and galactose, in controlling the differentiation or function of immune cells.

AIM OF REVIEW

Herein, we reviewed the latest research progresses in the hexose-mediated modulation of immune responses, provided in-depth analyses of the underlying mechanisms, and discussed the unresolved issues in this field.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Owing to their immunoregulatory effects, hexoses affect the onset and progression of various types of immune disorders, including inflammatory diseases, autoimmune diseases, and tumor immune evasion. Thus, targeting hexose metabolism is becoming a promising strategy for reversing immune abnormalities in diseases.

Amelioration of Central Nervous System Autoimmunity Through FFAR2 Agonism Is Associated With Changes in Gut Microbiota

PURPOSE

The intestinal immune compartment is increasingly recognized as an important player in central nervous system (CNS) autoimmunity. We have recently reported that oral administration of the free fatty acid receptor 2 (FFAR2) agonist Cpd1 in the inductive phase of experimental autoimmune encephalomyelitis (EAE) in rats ameliorates the disease by stimulating the regulatory immune response in the intestine.

METHOD

Here, the effects of Cpd1 on the gut microbiota and short-chain fatty acid (SCFA) composition were investigated in the same experimental system.

FINDING

Increased levels of the phylum Proteobacteria, the class Gammaproteobacteria, the orders Burkholderiales and Erysipelotrichales, the families Sutterellaceae and Erysipelotrichaceae, and the genera Parasutterella and Faecalibaculum were observed in agonist-treated rats. The genera Allobaculum and Ileibacterium were only detected in the agonist-treated group. The treatment led to changes in the functional profile of the gut microbiota both in the KEGG orthologous pathways and in the clusters of orthologous genes. In addition, an altered profile of intestinal SCFA content was observed in the agonist-treated group.

CONCLUSION

The effects of Cpd1 on the gut microbiota and SCFA composition are relevant to the observed treatment benefit of FFAR2 agonism in the EAE model during the inductive phase of the disease.

Beyond nutritional immunity: immune-stressing challenges basic paradigms of immunometabolism and immunology

Pathogens have the well-known advantage of rapid evolution due to short generation times and large populations. However, pathogens have the rarely noted disadvantage of the vulnerability to stress involved in proliferation as well as being localized. Presented here are numerous new paradigms in immunology, and especially immunometabolism, which are derived from examining how hosts capitalize on pathogen vulnerabilities to stress. Universally, proliferation requires both resources and synthesis, which are vulnerable to resource-limiting stress and damaging/noxious stress, respectively. Pathogens are particularly vulnerable to stress at the time when they are most threatening-when they are proliferating. Since immune cells actively controlling pathogens (effector cells) typically do not proliferate at infected sites, there is a "stress vulnerability gap" wherein proliferating pathogens are more vulnerable to any type of stress than are the attacking effector cells. Hosts actively stress vulnerable proliferating pathogens by restricting resources (resource-limiting stress) and generating noxious waste products (damaging/disruptive stress) in a fundamental defense here-in termed "immune-stressing." While nutritional immunity emphasizes denying pathogens micronutrients, immune-stressing extends the concept to restricting all resources, especially glucose and oxygen, coupled with the generation of noxious metabolic products such as lactic acid, reactive oxygen species (ROS), and heat to further harm or stress the pathogens. At present much of the field of immunometabolism centers on how nutrition and metabolism regulate immune function, a central feature being the inefficient use of glucose via aerobic glycolysis (with much lactate/lactic acid production) by effector immune cells. In contrast, immune-stressing emphasizes how the immune system uses nutrition and metabolism to control infections. Immune-stressing addresses effector cell glycolysis at the infected site by noting that the high uptake of glucose linked with high output of lactic acid is an ideal double-pronged stressor targeting proliferating pathogens. Once the basic vulnerability of pathogen proliferation is recognized, numerous other paradigms of immunometabolism, and immunology as a whole, are challenged.

Cellular respiration in dendritic cells: Exploring oxygen-dependent pathways for potential therapeutic interventions

Dendritic cells (DCs) are specialized antigen-presenting cells crucial for initiating and regulating adaptive immune responses, making them promising candidates for therapeutic interventions in various immune-mediated diseases. Increasing evidence suggests that the microenvironment in which cells are cultured, as well as the milieu in which they perform their functions, significantly impact their immunomodulatory properties. Among these environmental factors, the role of oxygen in DC biology and its significance for both their in vitro generation and in vivo therapeutic application require investigation. Unlike the atmospheric oxygen level of 21 % commonly used in in vitro assays, physiological oxygen levels are much lower (3-9 %), and hypoxia (<1.3 %) is a prevalent condition of both healthy tissues and disease states. This mismatch between laboratory and physiological conditions underscores the critical need to culture and evaluate therapeutic cells under physiologically relevant oxygen levels to improve their translational relevance and clinical outcomes. This review explores the characteristic hallmarks of human DCs that are influenced by oxygen-dependent pathways, including metabolism, phenotype, cytokine secretion, and migration. Furthermore, we discuss the potential of manipulating oxygen levels to refine the generation and functionality of DCs for therapeutic purposes.

Emerging role of metabolic reprogramming in the immune microenvironment and immunotherapy of thyroid cancer

The metabolic reprogramming of cancer cells is a hallmark of many malignancies. To meet the energy acquisition needs of tumor cells for rapid proliferation, tumor cells reprogram their nutrient metabolism, which is caused by the abnormal expression of transcription factors and signaling molecules related to energy metabolic pathways as well as the upregulation and downregulation of abnormal metabolic enzymes, receptors, and mediators. Thyroid cancer (TC) is the most common endocrine tumor, and immunotherapy has become the mainstream choice for clinical benefit after the failure of surgical, endocrine, and radioiodine therapies. TC change the tumor microenvironment (TME) through nutrient competition and metabolites, causing metabolic reprogramming of immune cells, profoundly changing immune cell function, and promoting immune evasion of tumor cells. A deeper understanding of how metabolic reprogramming alters the TME and controls immune cell fate and function will help improve the effectiveness of TC immunotherapy and patient outcomes. This paper aims to elucidate the metabolic communication that occurs between immune cells around TC and discusses how metabolic reprogramming in TC affects the immune microenvironment and the effectiveness of anti-cancer immunotherapy. Finally, targeting key metabolic checkpoints during metabolic reprogramming, combined with immunotherapy, is a promising strategy.

Systemic immune-inflammation states in US adults with seropositivity to infectious pathogens: A nutrient-wide association study

BACKGROUND

Limited understanding exists regarding the association between daily total dietary nutrient intakes and immune-inflammation states in US adults exposed to various pathogens. This study sought to examine the correlation between nutrient intakes and immune-inflammation indicators and to assess their performance in distinguishing immune-inflammation states.

METHODS

This study was derived from the National Health and Nutrition Examination Survey (NHANES), which included 33,804 participants aged 20 years or older between 2005 and 2018. Multivariable linear regression and restricted cubic spline regression were conducted to evaluate the association between nutrient intakes and immune-inflammation indicators. Receiver operating characteristic curve analysis was performed to evaluate the discriminatory performance of identified nutrients for various immune-inflammation states measured by the systemic immune-inflammation index (SII).

RESULTS

Ten key nutrients were significantly associated with immune-inflammation responses, including calcium, saturated fatty acid (SFA) 4:0, SFA 6:0, SFA 12:0, SFA 14:0, SFA 16:0, vitamin B2, total SFAs, retinol, and lutein + zeaxanthin, which show potential as dietary indicators. The area under the curve for discriminating various immune-inflammation states was improved by at least 0.03 compared with a model that included only covariates, with all P values <0.05 in the Delong tests, indicating a significant enhancement in model performance.

CONCLUSIONS

Ten nutrients, including calcium, various SFAs, vitamin B2, retinol, and lutein + zeaxanthin, exhibit significant association with SII and potential as dietary indicators for distinguishing between different immune-inflammation states in US adults with seropositivity to various viruses.

Chronic bacterial infections exert metabolic costs in Drosophila melanogaster

Bacterial infections can substantially impact host metabolic health as a result of the direct and indirect demands of sustaining an immune response and of nutrient piracy by the pathogen itself. Drosophila melanogaster and other insects that survive a sublethal bacterial infection often carry substantial pathogen burdens for the remainder of life. In this study, we asked whether these chronic infections exact metabolic costs for the host, and how these costs scale with the severity of chronic infection. We infected D. melanogaster with four bacterial species (Providencia rettgeri, Serratia marcescens, Enterococcus faecalis and Lactococcus lactis) and assayed metabolic traits in chronically infected survivors. We found that D. melanogaster carrying chronic infections were uniformly more susceptible to starvation than uninfected controls, and that sensitivity to starvation escalated with higher chronic pathogen burden. We observed some evidence for greater depletion of triglyceride and glycogen stores in D. melanogaster carrying chronic bacterial loads, although this varied among bacterial species. Chronically infected flies exhibit sustained upregulation of the immune response, which we hypothesized might contribute to the metabolic costs. Consistent with this prediction, genetic activation of the major innate immune signaling pathways depleted metabolic stores and increased starvation sensitivity even in the absence of infection. These results demonstrate that even sublethal infections can have substantial health and fitness consequences for the hosts, arising in part from pathogen-induced immune activation, and that the consequences scale quantitatively with the severity of infection.

Review: Feed efficiency and metabolic flexibility in livestock

Improving the conversion of feed into product has been a key focus of genetic improvement in all livestock species. Livestock feed efficiency is the amount of product produced per unit of feed intake. Feed efficiency also depends on processes that are not directly related to economically important phenotypes, which can be considered 'waste' from a production point of view but are vital maintenance-related functions that are closely associated with environmental flexibility and adaptation. Resource allocation theory suggests that an animal's resource budget is narrowed when production efficiency is improved through an increase in productive output, along with a decrease in feed intake (capacity) and body reserves (improved leanness). The resulting trade-offs between productivity and vital functions may render the animal less capable of responding to unexpected challenges, potentially leading to negative side effects that are not directly related to economically important phenotypes. However, selection for feed efficiency may not narrow the metabolic space and result in trade-offs if the increase in feed efficiency is the result of increased metabolic flexibility in fuel substrate choice (carbohydrates, lipids, and/or proteins) and other energy-saving strategies. This review evaluates the relationship between metabolic flexibility and feed efficiency during anabolism (growth), fasting, immune activation, general stress, and heat stress, with a focus on pig production. We start with a brief overview of energy processes and substrate metabolism of carbohydrates, lipids, and protein. During muscle metabolism, the type of fuel used depends on fibre type characteristics of the muscle. Selection for improved meat production has resulted in pigs with a greater abundance of fast-twitch fibres with lower energy expenditure and higher metabolic efficiency. Metabolic flexibility for adaptation to disease, and response to regular stress implies that a more reactive immune response and reduced fear response results in higher feed efficiency. The examples presented in this review show that selection for improved feed efficiency does not necessarily narrow the metabolic space and result in trade-offs between productivity and vital functions because of energy-sparing mechanisms.

Spatial diversity of in vivo tissue immunity

The immune system exhibits spatial diversity in in vivo tissues. Immune cells are strategically distributed within tissues to maintain the organ integrity. Advanced technologies such as intravital imaging and spatial transcriptomics have revealed the spatial heterogeneity of immune cell distribution and function within organs such as the liver, kidney, intestine, and lung. In addition, these technologies visualize nutrient and oxygen environments across tissues. Recent spatial analyses have suggested that a functional immune niche is determined by interactions between immune and non-immune cells in an appropriate nutrient and oxygen environment. Understanding the spatial communication between immune cells, environment, and surrounding non-immune cells is crucial for developing strategies to control immune responses and effectively manage inflammatory diseases.

Nanocarriers for Delivery of Anticancer Drugs: Current Developments, Challenges, and Perspectives

Cancer, the most common condition worldwide, ranks second in terms of the number of human deaths, surpassing cardiovascular diseases. Uncontrolled cell multiplication and resistance to cell death are the traditional features of cancer. The myriad of treatment options include surgery, chemotherapy, radiotherapy, and immunotherapy to treat this disease. Conventional chemotherapy drug delivery suffers from issues such as the risk of damage to benign cells, which can cause toxicity, and a few tumor cells withstand apoptosis, thereby increasing the likelihood of developing tolerance. The side effects of cancer chemotherapy are often more pronounced than its benefits. Regarding drugs used in cancer chemotherapy, their bioavailability and stability in the tumor microenvironment are the most important issues that need immediate addressing. Hence, an effective and reliable drug delivery system through which both rapid and precise targeting of treatment can be achieved is urgently needed. In this work, we discuss the development of various nanobased carriers in the advancement of cancer therapy-their properties, the potential of polymers for drug delivery, and recent advances in formulations. Additionally, we discuss the use of tumor metabolism-rewriting nanomedicines in strengthening antitumor immune responses and mRNA-based nanotherapeutics in inhibiting tumor progression. We also examine several issues, such as nanotoxicological studies, including their distribution, pharmacokinetics, and toxicology. Although significant attention is being given to nanotechnology, equal attention is needed in laboratories that produce nanomedicines so that they can record themselves in clinical trials. Furthermore, these medicines in clinical trials display overwhelming results with reduced side effects, as well as their ability to modify the dose of the drug.

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

Germinal center (GC) formation, which is an integrant part of humoral immunity, involves energy-consuming metabolic reprogramming. Rag-GTPases are known to signal amino acid availability to cellular pathways that regulate nutrient distribution such as the mechanistic target of rapamycin complex 1 (mTORC1) pathway and the transcription factors TFEB and TFE3. However, the contribution of these factors to 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 to generate plasmablasts during 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 the Rag GTPase-TFEB/TFE3 pathway as a likely mTORC1 independent mechanism to coordinating nutrient sensing and mitochondrial metabolism in B cells.

Metabolic reprogramming and therapeutic resistance in primary and metastatic breast cancer

Metabolic alterations, a hallmark of cancer, enable tumor cells to adapt to their environment by modulating glucose, lipid, and amino acid metabolism, which fuels rapid growth and contributes to treatment resistance. In primary breast cancer, metabolic shifts such as the Warburg effect and enhanced lipid synthesis are closely linked to chemotherapy failure. Similarly, metastatic lesions often display distinct metabolic profiles that not only sustain tumor growth but also confer resistance to targeted therapies and immunotherapies. The review emphasizes two major aspects: the mechanisms driving metabolic resistance in both primary and metastatic breast cancer, and how the unique metabolic environments in metastatic sites further complicate treatment. By targeting distinct metabolic vulnerabilities at both the primary and metastatic stages, new strategies could improve the efficacy of existing therapies and provide better outcomes for breast cancer patients.

An early, novel arginine methylation of KCa3.1 attenuates subsequent T cell exhaustion

T cell receptor (TCR) engagement initiates the activation process, and this signaling event is regulated in multifaceted ways. Nutrient availability in the immediate niche is one such mode of regulation 1-3 . Here, we investigated how the availability of an essential amino acid methionine (Met) and TCR signaling might interplay in the earliest events of T cell activation to affect subsequent T cell fate and function. We found that limiting Met during only the initial 30 minutes of CD8 + T cell activation increased Ca 2+ influx, Ca 2+ -mediated NFAT1 ( Nfatc2 ) activation, NFAT1 promoter occupancy, and T cell exhaustion. We identified changes in the protein arginine methylome during the initial 30 min of TCR engagement and discovered a novel arginine methylation of a Ca 2+ -activated potassium transporter, KCa3.1, which regulates Ca 2+ -mediated NFAT1 signaling to ensure optimal activation. Ablation of arginine methylation in KCa3.1 led to increased NFAT1 activation, rendering T cells dysfunctional in murine tumour and infection models. Furthermore, acute Met supplementation at early stages reduced nuclear NFAT1 in tumour-infiltrating T cells and augmented their anti-tumour activity. Our findings identify a metabolic event occurring early after T cell activation that influences the subsequent fate of the cell.

Metabolism and epigenetics: drivers of tumor cell plasticity and treatment outcomes

Emerging evidence indicates that metabolism not only is a source of energy and biomaterials for cell division but also acts as a driver of cancer cell plasticity and treatment resistance. This is because metabolic changes lead to remodeling of chromatin and reprogramming of gene expression patterns, furthering tumor cell phenotypic transitions. Therefore, the crosstalk between metabolism and epigenetics seems to hold immense potential for the discovery of novel therapeutic targets for various aggressive tumors. Here, we highlight recent discoveries supporting the concept that the cooperation between metabolism and epigenetics enables cancer to overcome mounting treatment-induced pressures. We discuss how specific metabolites contribute to cancer cell resilience and provide perspective on how simultaneously targeting these key forces could produce synergistic therapeutic effects to improve treatment outcomes.

Fecal Microbiota Transplantation: Insights into Colon Carcinogenesis and Immune Regulation

Colorectal cancer (CRC) constitutes a significant global health challenge, with recent studies underscoring the pivotal role of the gut microbiome in its pathogenesis and progression. Fecal microbiota transplantation (FMT) has emerged as a compelling therapeutic approach, offering the potential to modulate microbial composition and optimize treatment outcomes. Research suggests that specific bacterial strains are closely linked to CRC, influencing both its clinical management and therapeutic interventions. Moreover, the gut microbiome's impact on immunotherapy responsiveness heralds new avenues for personalized medicine. Despite the promise of FMT, safety concerns, particularly in immunocompromised individuals, remain a critical issue. Clinical outcomes vary widely, influenced by genetic predispositions and the specific transplantation methodologies employed. Additionally, rigorous donor selection and screening protocols are paramount to minimize risks and maximize therapeutic efficacy. The current body of literature advocates for the establishment of standardized protocols and further clinical trials to substantiate FMT's role in CRC management. As our understanding of the microbiome deepens, FMT is poised to become a cornerstone in CRC treatment, underscoring the imperative for continued research and clinical validation.

Spatial heterogeneity and functional zonation of living tissues and organs in situ

In most organs, resources such as nutrients, oxygen and physiologically active substances are unevenly supplied within the tissue spaces. Consequently, different tissue functions are exhibited in each space. This spatial heterogeneity of tissue environments arises depending on the spatial arrangement of nutrient vessels and functional vessels, leading to continuous changes in the metabolic states and functions of various cell types from regions proximal to these vessels to distant regions. This phenomenon is referred to as 'zonation'. Traditional analytical methods have made it difficult to investigate this zonation in detail. However, recent advancements in intravital imaging, spatial transcriptomics and single-cell transcriptomics technologies have facilitated the discovery of 'zones' in various organs and elucidated their physiological roles. Here, we outline the spatial differences in the immune system within each zone of organs. This information provides a deeper understanding of organs' immune systems.

Value of the lung immune prognostic index in patients with advanced small cell lung cancer treated with programmed death-ligand 1 and programmed death-1 inhibitors in the Chinese alpine region

Purpose

To assess the potential added value of the lung immune prognostic index (LIPI) in patients with small cell lung cancer (SCLC), treated with programmed death-ligand 1 (PD-L1)/programmed death-1 (PD-1) inhibitors, who lived in the Chinese alpine region.

Methods

120 SCLC patients treated with PD-L1/PD-1 inhibitors were divided into three LIPI groups, from July 2018 to April 2021. Cox regression models were used to evaluate the prognostic effect of three LIPI groups on overall survival (OS) and progression-free survival (PFS). Logistic regression analysis was conducted to explore the association between immune-related adverse events (irAEs) and the pretreatment of neutrophil-to-lymphocyte ratio (dNLR), lactate dehydrogenase (LDH), and LIPI.

Results

The median OS was 4.5, 6.3, and 10.0 months (p=0.001) and the median PFS was 2.5, 4.3, and 5.3 months (p=0.049) for Poor, Intermediate, and Good LIPI, respectively. The disease control rate (DCR) was also higher in the Good LIPI group (p=0.003). Moreover, multivariate analysis confirmed that worse LIPI was correlated with shorter OS and PFS. dNLR was associated with the onset of irAEs, not LIPI. Conclusion: The LIPI might be a promising predictive and prognostic biomarker in SCLC patients treated with PD-L1/PD-1 inhibitors in the Chinese Alpine region.

Activation induces shift in nutrient utilization that differentially impacts cell functions in human neutrophils

Neutrophils utilize a variety of metabolic sources to support their crucial functions as the first responders in innate immunity. Here, through in vivo and ex vivo isotopic tracing, we examined the contributions of different nutrients to neutrophil metabolism under specific conditions. Human peripheral blood neutrophils, in contrast to a neutrophil-like cell line, rely on glycogen storage as a major metabolic source under resting state but rapidly switch to primarily using extracellular glucose upon activation with various stimuli. This shift is driven by a substantial increase in glucose uptake, enabled by rapidly increased GLUT1 on cell membrane, that dominates the simultaneous increase in gross glycogen cycling capacity. Shifts in nutrient utilization impact neutrophil functions in a function-specific manner: oxidative burst depends on glucose utilization, whereas NETosis and phagocytosis can be flexibly supported by either glucose or glycogen, and neutrophil migration and fungal control are enhanced by the shift from glycogen utilization to glucose utilization. This work provides a quantitative and dynamic understanding of fundamental features in neutrophil metabolism and elucidates how metabolic remodeling shapes neutrophil functions, which has broad health relevance.

Nutrient starvation activates ECM remodeling gene enhancers associated with inflammatory bowel disease risk in fibroblasts

Nutrient deprivation induces a reversible cell cycle arrest state termed quiescence, which often accompanies transcriptional silencing and chromatin compaction. Paradoxically, nutrient deprivation is associated with activated fibroblast states in pathological microenvironments in which fibroblasts drive extracellular matrix (ECM) remodeling to alter tissue environments. The relationship between nutrient deprivation and fibroblast activation remains unclear. Here, we report that serum deprivation extensively activates transcription of ECM remodeling genes in cultured fibroblasts, despite the induction of quiescence. Starvation-induced transcriptional activation accompanied large-scale histone acetylation of putative distal enhancers, but not promoters. The starvation-activated putative enhancers were enriched for non-coding genetic risk variants associated with inflammatory bowel disease (IBD), suggesting that the starvation-activated gene regulatory network may contribute to fibroblast activation in IBD. Indeed, the starvation-activated gene PLAU, encoding uPA serine protease for plasminogen and ECM, was upregulated in inflammatory fibroblasts in the intestines of IBD patients. Furthermore, the starvation-activated putative enhancer at PLAU, which harbors an IBD risk variant, gained chromatin accessibility in IBD patient fibroblasts. This study implicates nutrient deprivation in transcriptional activation of ECM remodeling genes in fibroblasts and suggests nutrient deprivation as a potential mechanism for pathological fibroblast activation in IBD.

Triple threat: how diabetes results in worsened bacterial infections

Diabetes mellitus, characterized by impaired insulin signaling, is associated with increased incidence and severity of infections. Various diabetes-related complications contribute to exacerbated bacterial infections, including hyperglycemia, innate immune cell dysfunction, and infection with antibiotic-resistant bacterial strains. One defining symptom of diabetes is hyperglycemia, resulting in elevated blood and tissue glucose concentrations. Glucose is the preferred carbon source of several bacterial pathogens, and hyperglycemia escalates bacterial growth and virulence. Hyperglycemia promotes specific mechanisms of bacterial virulence known to contribute to infection chronicity, including tissue adherence and biofilm formation. Foot infections are a significant source of morbidity in individuals with diabetes and consist of biofilm-associated polymicrobial communities. Bacteria perform complex interspecies behaviors conducive to their growth and virulence within biofilms, including metabolic cross-feeding and altered phenotypes more tolerant to antibiotic therapeutics. Moreover, the metabolic dysfunction caused by diabetes compromises immune cell function, resulting in immune suppression. Impaired insulin signaling induces aberrations in phagocytic cells, which are crucial mediators for controlling and resolving bacterial infections. These aberrancies encompass altered cytokine profiles, the migratory and chemotactic mechanisms of neutrophils, and the metabolic reprogramming required for the oxidative burst and subsequent generation of bactericidal free radicals. Furthermore, the immune suppression caused by diabetes and the polymicrobial nature of the diabetic infection microenvironment may promote the emergence of novel strains of multidrug-resistant bacterial pathogens. This review focuses on the "triple threat" linked to worsened bacterial infections in individuals with diabetes: (i) altered nutritional availability in diabetic tissues, (ii) diabetes-associated immune suppression, and (iii) antibiotic treatment failure.

Metabolic reprogramming and immune evasion: the interplay in the tumor microenvironment

Tumor cells possess complex immune evasion mechanisms to evade immune system attacks, primarily through metabolic reprogramming, which significantly alters the tumor microenvironment (TME) to modulate immune cell functions. When a tumor is sufficiently immunogenic, it can activate cytotoxic T-cells to target and destroy it. However, tumors adapt by manipulating their metabolic pathways, particularly glucose, amino acid, and lipid metabolism, to create an immunosuppressive TME that promotes immune escape. These metabolic alterations impact the function and differentiation of non-tumor cells within the TME, such as inhibiting effector T-cell activity while expanding regulatory T-cells and myeloid-derived suppressor cells. Additionally, these changes lead to an imbalance in cytokine and chemokine secretion, further enhancing the immunosuppressive landscape. Emerging research is increasingly focusing on the regulatory roles of non-tumor cells within the TME, evaluating how their reprogrammed glucose, amino acid, and lipid metabolism influence their functional changes and ultimately aid in tumor immune evasion. Despite our incomplete understanding of the intricate metabolic interactions between tumor and non-tumor cells, the connection between these elements presents significant challenges for cancer immunotherapy. This review highlights the impact of altered glucose, amino acid, and lipid metabolism in the TME on the metabolism and function of non-tumor cells, providing new insights that could facilitate the development of novel cancer immunotherapies.

Cellular metabolism changes in atherosclerosis and the impact of comorbidities

Cell activation and nutrient dysregulation are common consequences of atherosclerosis and its preceding risk factors, such as hypertension, dyslipidemia, and diabetes. These diseases may also impact cellular metabolism and consequently cell function, and the other way around, altered cellular metabolism can impact disease development and progression through altered cell function. Understanding the contribution of altered cellular metabolism to atherosclerosis and how cellular metabolism may be altered by co-morbidities and atherosclerosis risk factors could support the development of novel strategies to lower the risk of CVD. Therefore, we briefly review disease pathogenesis and the principles of cell metabolic pathways, before detailing changes in cellular metabolism in the context of atherosclerosis and comorbidities. In the hypoxic, inflammatory and hyperlipidemic milieu of the atherosclerotic plaque riddled with oxidative stress, metabolism shifts to increase anaerobic glycolysis, the pentose-phosphate pathway and amino acid use. We elaborate on metabolic changes for macrophages, neutrophils, vascular endothelial cells, vascular smooth muscle cells and lymphocytes in the context of atherosclerosis and its co-morbidities hypertension, dyslipidemia, and diabetes. Since causal relationships of specific key genes in a metabolic pathway can be cell type-specific and comorbidity-dependent, the impact of cell-specific metabolic changes must be thoroughly explored in vivo, with a focus on also systemic effects. When cell-specific treatments become feasible, this information will be crucial for determining the best metabolic intervention to improve atherosclerosis and its interplay with co-morbidities.

A Bioorthogonal Dual Fluorogenic Probe for the Live-Cell Monitoring of Nutrient Uptake by Mammalian Cells

Cells rely heavily on the uptake of exogenous nutrients for survival, growth, and differentiation. Yet quantifying the uptake of small molecule nutrients at the single cell level is difficult. Here we present a new approach to studying the nutrient uptake in live single cells using Inverse Electron-Demand Diels Alder (IEDDA) chemistry. We have modified carboxyfluorescein-diacetate-succinimidyl esters (CFSE)-a quenched fluorophore that can covalently react with proteins and is only turned on in the cytosol of a cell following esterase activity-with a tetrazine. This tetrazine serves as a second quencher for the pendant fluorophore. Upon reaction with nutrients modified with an electron-rich or strained dienophile in an IEDDA reaction, this quenching group is destroyed, thereby enabling the probe to fluoresce. This has allowed us to monitor the uptake of a variety of dienophile-containing nutrients in live primary immune cell populations using flow cytometry and live-cell microscopy.

Immunological Insights Into Nutritional Deficiency Disorders

Essential nutrients play a vital role in influencing immune cell development. This chapter explores the crucial relationship between nutrition and the immune system, delving into the profound impact of dietary choices on overall health. Research highlights the benefits of nutrient-rich foods in supporting optimal immune function, while deficiencies in key nutrients (vitamins A, D, zinc, and iron) compromise immune responses, increasing susceptibility to infections. The bidirectional nature of the relationship is emphasized, underscoring the critical role of a balanced diet in supporting immune cell development, activation, and function. Case studies illustrate immunological vulnerabilities linked to inadequate nutritional status, stressing the importance of maintaining optimal nutrient levels for a robust immune system. In summary, an individual's nutritional status significantly influences immune response effectiveness. Addressing deficiencies through supplementation, dietary interventions, and public health initiatives is crucial for improving immune function.

Exploring the multifaceted role of obesity in breast cancer progression

Obesity is a multifaceted metabolic disorder characterized by excessive accumulation of adipose tissue. It is a well-established risk factor for the development and progression of breast cancer. Adipose tissue, which was once regarded solely as a passive energy storage depot, is now acknowledged as an active endocrine organ producing a plethora of bioactive molecules known as adipokines that contribute to the elevation of proinflammatory cytokines and estrogen production due to enhanced aromatase activity. In the context of breast cancer, the crosstalk between adipocytes and cancer cells within the adipose microenvironment exerts profound effects on tumor initiation, progression, and therapeutic resistance. Moreover, adipocytes can engage in direct interactions with breast cancer cells through physical contact and paracrine signaling, thereby facilitating cancer cell survival and invasion. This review endeavors to summarize the current understanding of the intricate interplay between adipocyte-associated factors and breast cancer progression. Furthermore, by discussing the different aspects of breast cancer that can be adversely affected by obesity, this review aims to shed light on potential avenues for new and novel therapeutic interventions.

Integration of multi-omics analysis reveals metabolic alterations of B lymphocytes in systemic lupus erythematosus

OBJECTIVE

To link changes in the B-cell transcriptome from systemic lupus erythematosus (SLE) patients with those in their macroenvironment, including cellular and fluidic components.

METHODS

Analysis was performed on 363 patients and 508 controls, encompassing transcriptomics, metabolomics, and clinical data. B-cell and whole-blood transcriptomes were analysed using DESeq and GSEA. Plasma and urine metabolomics peak changes were quantified and annotated using Ceu Mass Mediator database. Common sources of variation were identified using MOFA integration analysis.

RESULTS

Cellular macroenvironment was enriched in cytokines, stress responses, lipidic synthesis/mobility pathways and nucleotide degradation. B cells shared these pathways, except nucleotide degradation diverted to nucleotide salvage pathway, and distinct glycosylation, LPA receptors and Schlafen proteins.

CONCLUSIONS

B cells showed metabolic changes shared with their macroenvironment and unique changes directly or indirectly induced by IFN-α signalling. This study underscores the importance of understanding the interplay between B cells and their macroenvironment in SLE pathology.

Efficacy of mesenchymal stem cells in treating tracheoesophageal fistula via the TLR4/NF-κb pathway in beagle macrophages

Background

Tracheoesophageal fistula (TEF) remains a rare but significant clinical challenge, mainly due to the absence of established, effective treatment approaches. The current focus of therapeutic strategy is mainly on fistula closure. However, this approach often misses important factors, such as accelerating fistula contraction and fostering healing processes, which significantly increases the risk of disease recurrence.

Methods

In order to investigate if Mesenchymal Stem Cells (MSCs) can enhance fistula repair, developed a TEF model in beagles. Dynamic changes in fistula diameter were monitored by endoscopy. Concurrently, we created a model of LPS-induced macrophage to replicate the inflammatory milieu typical in TEF. In addition, the effect of MSC supernatant on inflammation mitigation was evaluated. Furthermore, we looked at the role of TLR4/NF-κB pathway plays in the healing process.

Results

Our research revealed that the local administration of MSCs significantly accelerated the fistula's healing process. This was demonstrated by a decline in TEF apoptosis and decrease in the production of pro-inflammatory cytokines. Furthermore, in vivo experiments demonstrated that the MSC supernatant was effective in suppressing pro-inflammatory cytokine expression and alleviating apoptosis in LPS-induced macrophages. These therapeutic effects were mainly caused by the suppression of TLR4/NF-κB pathway.

Conclusion

According to this study, MSCs can significantly improve TEF recovery. They achieve this via modulating apoptosis and inflammatory responses, mainly by selectively inhibiting the TLR4/NF-κB pathway.

Neutrophil glucose flux as a therapeutic target in antiphospholipid syndrome

Neutrophil hyperactivity and neutrophil extracellular trap release (NETosis) appear to play important roles in the pathogenesis of the thromboinflammatory autoimmune disease known as antiphospholipid syndrome (APS). The understanding of neutrophil metabolism has advanced tremendously in the past decade, and accumulating evidence suggests that a variety of metabolic pathways guide neutrophil activities in health and disease. Our previous work characterizing the transcriptome of APS neutrophils revealed that genes related to glycolysis, glycogenolysis, and the pentose phosphate pathway (PPP) were significantly upregulated. Here, we found that neutrophils from patients with APS used glycolysis more avidly than neutrophils from people in the healthy control group, especially when the neutrophils were from patients with APS with a history of microvascular disease. In vitro, inhibiting either glycolysis or the PPP tempered phorbol myristate acetate- and APS IgG-induced NETosis, but not NETosis triggered by a calcium ionophore. In mice, inhibiting either glycolysis or the PPP reduced neutrophil reactive oxygen species production and suppressed APS IgG-induced NETosis ex vivo. When APS-associated thrombosis was evaluated in mice, inhibiting either glycolysis or the PPP markedly suppressed thrombosis and circulating NET remnants. In summary, these data identify a potential role for restraining neutrophil glucose flux in the treatment of APS.

Increased Glycolytic Activity Is Part of Impeded M1(LPS) Macrophage Polarization in the Presence of Urolithin A

Urolithin A is a gut metabolite of ellagitannins and reported to confer health benefits, e.g., by increased clearance of damaged mitochondria by macroautophagy or curbed inflammation. One targeted cell type are macrophages, which are plastic and able to adopt pro- or anti-inflammatory polarization states, usually assigned as M1 and M2 macrophages, respectively. This flexibility is tightly coupled to characteristic shifts in metabolism, such as increased glycolysis in M1 macrophages, and protein expression upon appropriate stimulation. This study aimed at investigating whether the anti-inflammatory properties of U: rolithin A may be driven by metabolic alterations in cultivated murine M1(lipopolysaccharide) macrophages. Expression and extracellular flux analyses showed that urolithin A led to reduced il1β, il6, and nos2 expression and boosted glycolytic activity in M1(lipopolysaccharide) macrophages. The pro-glycolytic feature of UROLITHIN A: occurred in order to causally contribute to its anti-inflammatory potential, based on experiments in cells with impeded glycolysis. Mdivi, an inhibitor of mitochondrial fission, blunted increased glycolytic activity and reduced M1 marker expression in M1(lipopolysaccharide/UROLITHIN A: ), indicating that segregation of mitochondria was a prerequisite for both actions of UROLITHIN A: . Overall, we uncovered a so far unappreciated metabolic facet within the anti-inflammatory activity of UROLITHIN A: and call for caution about the simplified notion of increased aerobic glycolysis as an inevitably proinflammatory feature in macrophages upon exposure to natural products.

Metabolic heterogeneity in tumor microenvironment - A novel landmark for immunotherapy

The surrounding non-cancer cells and tumor cells that make up the tumor microenvironment (TME) have various metabolic rhythms. TME metabolic heterogeneity is influenced by the intricate network of metabolic control within and between cells. DNA, protein, transport, and microbial levels are important regulators of TME metabolic homeostasis. The effectiveness of immunotherapy is also closely correlated with alterations in TME metabolism. The response of a tumor patient to immunotherapy is influenced by a variety of variables, including intracellular metabolic reprogramming, metabolic interaction between cells, ecological changes within and between tumors, and general dietary preferences. Although immunotherapy and targeted therapy have made great strides, their use in the accurate identification and treatment of tumors still has several limitations. The function of TME metabolic heterogeneity in tumor immunotherapy is summarized in this article. It focuses on how metabolic heterogeneity develops and is regulated as a tumor progresses, the precise molecular mechanisms and potential clinical significance of imbalances in intracellular metabolic homeostasis and intercellular metabolic coupling and interaction, as well as the benefits and drawbacks of targeted metabolism used in conjunction with immunotherapy. This offers insightful knowledge and important implications for individualized tumor patient diagnosis and treatment plans in the future.

Effect of serum metabolites on the risk of iridocyclitis: a bidirectional Mendelian randomization study

Previous research has linked serum metabolite levels to iridocyclitis, yet their causal relationship remains unexplored. This study investigated this potential causality by analyzing pooled data from 7824 iridocyclitis patients in a Genome-Wide Association Study (GWAS) using Mendelian randomization (MR) and linkage disequilibrium score regression (LDSC). Employing rigorous quality control and comprehensive statistical methods, including sensitivity analyses, we examined the influence of 486 serum metabolites on iridocyclitis. Our MR analysis identified 23 metabolites with significant causal effects on iridocyclitis, comprising 17 known and 6 unidentified metabolites. Further refinement using Cochran's Q test and MR-PRESSO indicated 16 metabolites significantly associated with iridocyclitis risk. LDSC highlighted the heritability of certain metabolites, underscoring genetic influences on their levels. Notably, tryptophan, proline, theobromine, and 7-methylxanthine emerged as risk factors, while 3,4-dihydroxybutyrate appeared protective. These findings enhance our understanding of the metabolic interactions in iridocyclitis, offering insights for diagnosis, unraveling pathophysiological mechanisms, and informing potential avenues for prevention and personalized treatment.

Dysregulated cellular metabolism in atherosclerosis: mediators and therapeutic opportunities

Accumulating evidence over the past decades has revealed an intricate relationship between dysregulation of cellular metabolism and the progression of atherosclerotic cardiovascular disease. However, an integrated understanding of dysregulated cellular metabolism in atherosclerotic cardiovascular disease and its potential value as a therapeutic target is missing. In this Review, we (1) summarize recent advances concerning the role of metabolic dysregulation during atherosclerosis progression in lesional cells, including endothelial cells, vascular smooth muscle cells, macrophages and T cells; (2) explore the complexity of metabolic cross-talk between these lesional cells; (3) highlight emerging technologies that promise to illuminate unknown aspects of metabolism in atherosclerosis; and (4) suggest strategies for targeting these underexplored metabolic alterations to mitigate atherosclerosis progression and stabilize rupture-prone atheromas with a potential new generation of cardiovascular therapeutics.

A redox-responsive prodrug for tumor-targeted glutamine restriction

Modulating the metabolism of cancer cells, immune cells, or both is a promising strategy to potentiate cancer immunotherapy in the nutrient-competitive tumor microenvironment. Glutamine has emerged as an ideal target as cancer cells highly rely on glutamine for replenishing the tricarboxylic acid cycle in the process of aerobic glycolysis. However, non-specific glutamine restriction may induce adverse effects in unconcerned tissues and therefore glutamine inhibitors have achieved limited success in the clinic so far. Here we report the synthesis and evaluation of a redox-responsive prodrug of 6-Diazo-5-oxo-L-norleucine (redox-DON) for tumor-targeted glutamine inhibition. When applied to treat mice bearing subcutaneous CT26 mouse colon carcinoma, redox-DON exhibited equivalent antitumor efficacy but a greatly improved safety profile, particularly, in spleen and gastrointestinal tract, as compared to the state-of-the-art DON prodrug, JHU083. Furthermore, redox-DON synergized with checkpoint blockade antibodies leading to durable cures in tumor-bearing mice. Our results suggest that redox-DON is a safe and effective therapeutic for tumor-targeted glutamine inhibition showing promise for enhanced metabolic modulatory immunotherapy. The approach of reversible chemical modification may be generalized to other metabolic modulatory drugs that suffer from overt toxicity.

Nucleosides are overlooked fuels in central carbon metabolism

From our daily nutrition and synthesis within cells, nucleosides enter the bloodstream and circulate throughout the body and tissues. Nucleosides and nucleotides are classically viewed as precursors of nucleic acids, but recently they have emerged as a novel energy source for central carbon metabolism. Through catabolism by nucleoside phosphorylases, the ribose sugar group is released and can provide substrates for lower steps in glycolysis. In environments with limited glucose, such as at sites of infection or in the tumor microenvironment (TME), cells can use, and may even require, this alternative energy source. Here, we discuss the implications of these new findings in health and disease and speculate on the potential new roles of nucleosides and nucleic acids in energy metabolism.

Rag-GTPase-TFEB/TFE3 axis controls B cell mitochondrial fitness and humoral immunity independent of mTORC1

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 axis as an mTORC1 independent mechanism to coordinating nutrient sensing and mitochondrial metabolism in B cells.

Defective mitochondria remodelling in B cells leads to an aged immune response

The B cell response in the germinal centre (GC) reaction requires a unique bioenergetic supply. Although mitochondria are remodelled upon antigen-mediated B cell receptor stimulation, mitochondrial function in B cells is still poorly understood. To gain a better understanding of the role of mitochondria in B cell function, here we generate mice with B cell-specific deficiency in Tfam, a transcription factor necessary for mitochondrial biogenesis. Tfam conditional knock-out (KO) mice display a blockage of the GC reaction and a bias of B cell differentiation towards memory B cells and aged-related B cells, hallmarks of an aged immune response. Unexpectedly, blocked GC reaction in Tfam KO mice is not caused by defects in the bioenergetic supply but is associated with a defect in the remodelling of the lysosomal compartment in B cells. Our results may thus describe a mitochondrial function for lysosome regulation and the downstream antigen presentation in B cells during the GC reaction, the dysruption of which is manifested as an aged immune response.

Harnessing Immune Cell Metabolism to Modulate Alloresponse in Transplantation

Immune cell metabolism plays a pivotal role in shaping and modulating immune responses. The metabolic state of immune cells influences their development, activation, differentiation, and overall function, impacting both innate and adaptive immunity. While glycolysis is crucial for activation and effector function of CD8 T cells, regulatory T cells mainly use oxidative phosphorylation and fatty acid oxidation, highlighting how different metabolic programs shape immune cells. Modification of cell metabolism may provide new therapeutic approaches to prevent rejection and avoid immunosuppressive toxicities. In particular, the distinct metabolic patterns of effector and suppressive cell subsets offer promising opportunities to target metabolic pathways that influence immune responses and graft outcomes. Herein, we review the main metabolic pathways used by immune cells, the techniques available to assay immune metabolism, and evidence supporting the possibility of shifting the immune response towards a tolerogenic profile by modifying energetic metabolism.

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.

A glutamine tug-of-war between cancer and immune cells: recent advances in unraveling the ongoing battle

Glutamine metabolism plays a pivotal role in cancer progression, immune cell function, and the modulation of the tumor microenvironment. Dysregulated glutamine metabolism has been implicated in cancer development and immune responses, supported by mounting evidence. Cancer cells heavily rely on glutamine as a critical nutrient for survival and proliferation, while immune cells require glutamine for activation and proliferation during immune reactions. This metabolic competition creates a dynamic tug-of-war between cancer and immune cells. Targeting glutamine transporters and downstream enzymes involved in glutamine metabolism holds significant promise in enhancing anti-tumor immunity. A comprehensive understanding of the intricate molecular mechanisms underlying this interplay is crucial for developing innovative therapeutic approaches that improve anti-tumor immunity and patient outcomes. In this review, we provide a comprehensive overview of recent advances in unraveling the tug-of-war of glutamine metabolism between cancer and immune cells and explore potential applications of basic science discoveries in the clinical setting. Further investigations into the regulation of glutamine metabolism in cancer and immune cells are expected to yield valuable insights, paving the way for future therapeutic interventions.

Cardiac macrophage metabolism in health and disease

Cardiac macrophages are essential mediators of cardiac development, tissue homeostasis, and response to injury. Cell-intrinsic shifts in metabolism and availability of metabolites regulate macrophage function. The human and mouse heart contain a heterogeneous compilation of cardiac macrophages that are derived from at least two distinct lineages. In this review, we detail the unique functional roles and metabolic profiles of tissue-resident and monocyte-derived cardiac macrophages during embryonic development and adult tissue homeostasis and in response to pathologic and physiologic stressors. We discuss the metabolic preferences of each macrophage lineage and how metabolism influences monocyte fate specification. Finally, we highlight the contribution of cardiac macrophages and derived metabolites on cell-cell communication, metabolic health, and disease pathogenesis.

Nutrient availability regulates the secretion and function of immune cell-derived extracellular vesicles through metabolic rewiring

Extracellular vesicle (EV)-based immunotherapeutics have emerged as promising strategy for treating diseases, and thus, a better understanding of the factors that regulate EV secretion and function can provide insights into developing advanced therapies. Here, we report that nutrient availability, even changes in individual nutrient components, may affect EV biogenesis and composition of immune cells [e.g., macrophages (Mφs)]. As a proof of concept, EVs from M1-Mφ under glutamine-depleted conditions (EVGLN-) had higher yields, functional compositions, and immunostimulatory potential than EVs from conventional GLN-present medium (EVGLN+). Mechanistically, the systemic metabolic rewiring (e.g., altered energy and redox metabolism) induced by GLN depletion resulted in up-regulated pathways related to EV biogenesis/cargo sorting (e.g., ESCRT) and immunostimulatory molecule production (e.g., NF-κB and STAT) in Mφs. This study highlights the importance of nutrient status in EV secretion and function, and optimizing metabolic states and/or integrating them with other engineering methods may advance the development of EV therapeutics.

Glycogen metabolism-mediated intercellular communication in the tumor microenvironment influences liver cancer prognosis

Glycogen metabolism plays a key role in the development of hepatocellular carcinoma (HCC), but the function of glycogen metabolism genes in the tumor microenvironment (TME) is still to be elucidated. Single-cell RNA-seq data were obtained from ten HCC tumor samples totaling 64,545 cells, and 65 glycogen metabolism genes were analyzed by a nonnegative matrix factorization (NMF). The prognosis and immune response of new glycogen TME cell clusters were predicted by using HCC and immunotherapy cohorts from public databases. HCC single-cell analysis was divided into fibroblasts, NT T cells, macrophages, endothelial cells, and B cells, which were separately divided into new cell clusters by glycogen metabolism gene annotation. Pseudo-temporal trajectory analysis demonstrated the temporal differentiation trajectory of different glycogen subtype cell clusters. Cellular communication analysis revealed extensive interactions between endothelial cells with glycogen metabolizing TME cell-related subtypes and different glycogen subtype cell clusters. SCENIC analysis of transcription factors upstream of TME cell clusters with different glycogen metabolism. In addition, TME cell clusters of glycogen metabolism were found to be enriched in expression in CAF subtypes, CD8 depleted, M1, and M2 types. Bulk-seq analysis showed the prognostic significance of glycogen metabolism-mediated TME cell clusters in HCC, while a significant immune response was found in the immunotherapy cohort in patients treated with immune checkpoint blockade (ICB), especially for CAFs, T cells, and macrophages. In summary, our study reveals for the first time that glycogen metabolism mediates intercellular communication in the hepatocellular carcinoma microenvironment while elucidating the anti-tumor mechanisms and immune prognostic responses of different subtypes of cell clusters.

Cancer metabolism and carcinogenesis

Metabolic reprogramming is an emerging hallmark of cancer cells, enabling them to meet increased nutrient and energy demands while withstanding the challenging microenvironment. Cancer cells can switch their metabolic pathways, allowing them to adapt to different microenvironments and therapeutic interventions. This refers to metabolic heterogeneity, in which different cell populations use different metabolic pathways to sustain their survival and proliferation and impact their response to conventional cancer therapies. Thus, targeting cancer metabolic heterogeneity represents an innovative therapeutic avenue with the potential to overcome treatment resistance and improve therapeutic outcomes. This review discusses the metabolic patterns of different cancer cell populations and developmental stages, summarizes the molecular mechanisms involved in the intricate interactions within cancer metabolism, and highlights the clinical potential of targeting metabolic vulnerabilities as a promising therapeutic regimen. We aim to unravel the complex of metabolic characteristics and develop personalized treatment approaches to address distinct metabolic traits, ultimately enhancing patient outcomes.