Lipid signalling enforces functional specialization of Treg cells in tumours

Transcription factor Ikzf1 associates with Foxp3 to repress gene expression in Treg cells and limit autoimmunity and anti-tumor immunity

The master transcription factor of regulatory T (Treg) cells, forkhead box protein P3 (Foxp3), controls Treg cell function by targeting certain genes for activation or repression, but the specific mechanisms by which it mediates this activation or repression under different conditions remain unclear. We found that Ikzf1 associates with Foxp3 via its exon 5 (IkE5) and that IkE5-deficient Treg cells highly expressed genes that would otherwise be repressed by Foxp3 upon T cell receptor stimulation, including Ifng. Treg-specific IkE5-deletion caused interferon-γ (IFN-γ) overproduction, which destabilized Foxp3 expression and impaired Treg suppressive function, leading to systemic autoimmune disease and strong anti-tumor immunity. Pomalidomide, which degrades IKZF1 and IKZF3, induced IFN-γ overproduction in human Treg cells. Mechanistically, the Foxp3-Ikzf1-Ikzf3 complex competed with epigenetic co-activators, such as p300, for binding to target gene loci via chromatin remodeling. Therefore, the Ikzf1 association with Foxp3 is essential for the gene-repressive function of Foxp3 and could be exploited to treat autoimmune disease and cancer.

Cell Identity and Spatial Distribution of PD-1/PD-L1 Blockade Responders

The programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) axis inhibits T cell activity, impairing anti-tumor immunity. Blocking this axis with therapeutic antibodies is one of the most promising anti-tumor immunotherapies. It has long been recognized that PD-1/PD-L1 blockade reinvigorates exhausted T (TEX) cells already present in the tumor microenvironment (TME). However, recent advancements in high-throughput gene sequencing and bioinformatic tools have provided researchers with a more granular and dynamic insight into PD-1/PD-L1 blockade-responding cells, extending beyond the TME and TEX populations. This review provides an update on the cell identity, spatial distribution, and treatment-induced spatiotemporal dynamics of PD-1/PD-L1 blockade responders. It also provides a synopsis of preliminary reports of potential PD-1/PD-L1 blockade responders other than T cells to depict a panoramic picture. Important questions to answer in further studies and the translational and clinical potential of the evolving understandings are also discussed.

Infiltrating treg reprogramming in the tumor immune microenvironment and its optimization for immunotherapy

Immunotherapy has shown promising anti-tumor effects across various tumors, yet it encounters challenges from the inhibitory tumor immune microenvironment (TIME). Infiltrating regulatory T cells (Tregs) are important contributors to immunosuppressive TIME, limiting tumor immunosurveillance and blocking effective anti-tumor immune responses. Although depletion or inhibition of systemic Tregs enhances the anti-tumor immunity, autoimmune sequelae have diminished expectations for the approach. Herein, we summarize emerging strategies, specifically targeting tumor-infiltrating (TI)-Tregs, that elevate the capacity of organisms to resist tumors by reprogramming their phenotype. The regulatory mechanisms of Treg reprogramming are also discussed as well as how this knowledge could be utilized to develop novel and effective cancer immunotherapies.

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.

Gypenoside L inhibits hepatocellular carcinoma by targeting the SREBP2-HMGCS1 axis and enhancing immune response

Hepatocellular carcinoma (HCC) is a malignant tumor that occurs in the liver, with a high degree of malignancy and relatively poor prognosis. Gypenoside L has inhibitory effects on liver cancer cells. However, its mechanism of action is still unclear. This study aims to investigate the inhibitory effects of gypenoside L on HCC in vitro and in vivo, and explore its potential mechanisms. The results showed that gypenoside L reduced the cholesterol and triglyceride content in HepG2 and Huh-7 cells, inhibited cell proliferation, invasion and metastasis, arrested cell cycle at G0/G1 phase, promoted cell apoptosis. Mechanistically, it targeted the transcription factor SREPB2 to inhibit the expression of HMGCS1 protein and inhibited the downstream proteins HMGCR and MVK, thereby regulating the mevalonate (MVA) pathway. Overexpression HMGCS1 led to significant alterations in the cholesterol metabolism pathway of HCC, which mediated HCC cell proliferation and conferred resistance to the therapeutic effect of gypenoside L. In vivo, gypenoside L effectively suppressed HCC growth in tumor-bearing mice by reducing cholesterol production, exhibiting favorable safety profiles and minimal toxic side effects. Gypenoside L modulated cholesterol homeostasis, enhanced expression of inflammatory factors by regulating MHC I pathway-related proteins to augment anticancer immune responses. Clinical samples from HCC patients also exhibited high expression levels of MVA pathway-related genes in tumor tissues. These findings highlight gypenoside L as a promising agent for targeting cholesterol metabolism in HCC while emphasizing the effectiveness of regulating the SREBP2-HMGCS1 axis as a therapeutic strategy.

Unlocking the potential: Targeting metabolic pathways in the tumor microenvironment for Cancer therapy

Cancer incidence and mortality are increasing and impacting global life expectancy. Metabolic reprogramming in the tumor microenvironment (TME) is intimately related to tumorigenesis, progression, metastasis and drug resistance. Tumor cells drive metabolic reprogramming of other cells in the TME through metabolic induction of cytokines and metabolites, and metabolic substrate competition. Consequently, this boosts tumor cell growth by providing metabolic support and facilitating immunosuppression and angiogenesis. The metabolic interplay in the TME presents potential therapeutic targets. Here, we focus on the metabolic reprogramming of four principal cell subsets in the TME: CAFs, TAMs, TILs and TECs, and their interaction with tumor cells. We also summarize medications and therapies targeting these cells' metabolic pathways, particularly in the context of immune checkpoint blockade therapy.

Vitamin E and GPX4 cooperatively protect treg cells from ferroptosis and alleviate intestinal inflammatory damage in necrotizing enterocolitis

BACKGROUND

The notable decline in the number of Tregs within Necrotizing enterocolitis (NEC) intestinal tissues，contribute to excessive inflammation and necrosis, yet the precise underlying factors remain enigmatic. Ferroptosis, a novel cell death stemming from a disrupted lipid redox metabolism, is the focus of this investigation. Specifically, this study delves into the ferroptosis of Treg cells in the context of NEC and observes the protective effects exerted by vitamin E intervention, which aims to mitigate ferroptosis of Treg cells.

METHODS

To investigate the reduction of Treg cells in NEC intestine, we analyzed its association with ferroptosis from multiple angles. We constructed a mouse with a specific knockout of Gpx4 in Treg cells, aiming to examine the impact of Treg cell ferroptosis on NEC intestinal injury and localized inflammation. Ultimately, we employed vitamin E treatment to mitigate ferroptosis in NEC intestine's Treg cells, monitoring the subsequent amelioration in intestinal inflammatory damage.

RESULTS

The diminution of Treg cells in NEC is attributed to ferroptosis stemming from diminished GPX4 expression. Gpx4-deficient Treg cells exhibit impaired immunosuppressive function and are susceptible to ferroptosis. This ferroptosis of Treg cells exacerbates intestinal damage and inflammatory response in NEC. Notably, Vitamin E can inhibit the ferroptosis of Treg cells, subsequently alleviating intestinal damage and inflammation in NEC. Additionally, Vitamin E bolsters the anti-lipid peroxidation capability of Treg cells by upregulating the expression of GPX4.

CONCLUSION

In the context of NEC, the ferroptosis of Treg cells represents a significant factor contributing to intestinal tissue damage and an exaggerated inflammatory response. GPX4 is pivotal for the viability and functionality of Treg cells. Vitamin E exhibits the capability to mitigate the ferroptosis of Treg cells, thereby enhancing their number and function, which plays a crucial role in mitigating intestinal tissue damage and inflammatory response in NEC.

Cholesterol and Immune Microenvironment: Path Towards Tumorigenesis

PURPOSE OF REVIEW

Since obesity is a major risk factor for many different types of cancer, examining one of the most closely associated comorbidities, such as hypercholesterolemia, is crucial to understanding how obesity causes cancer. Hypercholesterolemia is usually associated with many cardiovascular complications such as hypertension, angina, and atherosclerosis. In addition, cholesterol may be a major factor in increasing cancer risk. Cancer patients who received statins, an anti-hypercholesteremic medicine, demonstrated improved prognosis possibly through its effect on tumor proliferation, apoptosis, and oxidative stress. Cholesterol could also aid in tumor progression through reprogramming tumor immunological architecture and mediators. This review focuses on the immunomodulatory role of cholesterol on cellular and molecular levels, which may explain its oncogenic driving activity. We look at how cholesterol modulates tumor immune cells like dendritic cells, T cells, Tregs, and neutrophils. Further, this study sheds light on the modification of the expression pattern of the common cancer-related immune mediators in the tumor immune microenvironment, such as programmed cell death 1 (PD-1), cytotoxic T lymphocyte antigen-4 (CTLA-4), transforming growth factor-beta (TGF-β), interleukin 12 (IL-12), IL-23, and forkhead box protein P3 (FOXP3).

RECENT FINDINGS

We highlight relevant literature demonstrating cholesterol's immunosuppressive role, leading to a worse cancer prognosis. This review invites further research regarding the pathobiological role of cholesterol in many obesity-related cancers such as uterine fibroids, post-menopausal breast, colorectal, endometrial, kidney, esophageal, pancreatic, liver, and gallbladder cancers. This review suggests that targeting cholesterol synthesis may be a fruitful approach to cancer targeting, in addition to traditional chemotherapeutics.

Inherent preference for polyunsaturated fatty acids instigates ferroptosis of Treg cells that aggravates high-fat-diet-related colitis

Inflammatory bowel disease (IBD) has high prevalence in Western counties. The high fat content in Western diets is one of the leading causes for this prevalence; however, the underlying mechanisms have not been fully defined. Here, we find that high-fat diet (HFD) induces ferroptosis of intestinal regulatory T (Treg) cells, which might be the key initiating step for the disruption of immunotolerance and the development of colitis. Compared with effector T cells, Treg cells favor lipid metabolism and prefer polyunsaturated fatty acids (PUFAs) for the synthesis of membrane phospholipids. Therefore, consumption of HFD, which has high content of PUFAs such as arachidonic acid, cultivates vulnerable Tregs that are fragile to lipid peroxidation and ferroptosis. Treg-cell-specific deficiency of GPX4, the key enzyme in maintaining cellular redox homeostasis and preventing ferroptosis, dramatically aggravates the pathogenesis of HFD-induced IBD. Taken together, these studies expand our understanding of IBD etiology.

Immune suppression by human thymus-derived effector Tregs relies on glucose/lactate-fueled fatty acid synthesis

Regulatory T cells (Tregs) suppress pro-inflammatory conventional T cell (Tconv) responses. As lipids impact cell signaling and function, we compare the lipid composition of CD4+ thymus-derived (t)Tregs and Tconvs. Lipidomics reveal constitutive enrichment of neutral lipids in Tconvs and phospholipids in tTregs. TNFR2-co-stimulated effector tTregs and Tconvs are both glycolytic, but only in tTregs are glycolysis and the tricarboxylic acid (TCA) cycle linked to a boost in fatty acid (FA) synthesis (FAS), supported by relevant gene expression. FA chains in tTregs are longer and more unsaturated than in Tconvs. In contrast to Tconvs, tTregs effectively use either lactate or glucose for FAS and rely on this process for proliferation. FASN and SCD1, enzymes responsible for FAS and FA desaturation, prove essential for the ability of tTregs to suppress Tconvs. These data illuminate how effector tTregs can thrive in inflamed or cancerous tissues with limiting glucose but abundant lactate levels.

Regulation of fatty acid synthase on tumor and progress in the development of related therapies

ABSTRACT

Fatty acid synthase (FASN) is an essential molecule in lipid metabolic pathways, which are crucial for cancer-related studies. Recent studies have focused on a comprehensive understanding of the novel and important regulatory effects of FASN on malignant biological behavior and immune-cell infiltration, which are closely related to tumor occurrence and development, immune escape, and immune response. FASN-targeting antitumor treatment strategies are being developed. Therefore, in this review, we focused on the effects of FASN on tumor and immune-cell infiltration and reviewed the progress of related anti-tumor therapy development.

Autocrine VEGF-B signaling maintains lipid synthesis and mitochondrial fitness to support T cell immune responses

T cells rewire their metabolic activities to meet the demand of immune responses, but how to coordinate the immune response by metabolic regulators in activated T cells is unknown. Here, we identified autocrine VEGF-B as a metabolic regulator to control lipid synthesis and maintain the integrity of the mitochondrial inner membrane for the survival of activated T cells. Disruption of autocrine VEGF-B signaling in T cells reduced cardiolipin mass, resulting in mitochondrial damage, with increased apoptosis and reduced memory development. The addition of cardiolipin or modulating VEGF-B signaling improved T cell mitochondrial fitness and survival. Autocrine VEGF-B signaling through GA-binding protein α (GABPα) induced sentrin/SUMO-specific protease 2 (SENP2) expression, which further de-SUMOylated PPARγ and enhanced phospholipid synthesis, leading to a cardiolipin increase in activated T cells. These data suggest that autocrine VEGF-B mediates a signal to coordinate lipid synthesis and mitochondrial fitness with T cell activation for survival and immune response. Moreover, autocrine VEGF-B signaling in T cells provides a therapeutic target against infection and tumors as well as an avenue for the treatment of autoimmune diseases.

Regulatory T cells in the context: deciphering the dynamic interplay with the tissue environment

The delicate balance between protective immunity against pathogens and the prevention of autoimmunity requires finely tuned generation and function of regulatory CD4+ T (Treg) cells. Here, we review recent progress in the understanding of a complex set of cues, which converge on Treg cells in lymphoid and nonlymphoid organs and in tumors and how these cues modulate Treg functions. We highlight the versatility of Treg cells underlying their ability to dynamically adapt to local microenvironments and perform a wide range of functions that extend beyond the archetypal role of Treg cells in moderating adverse effects of immune response-associated inflammation and in suppressing autoimmunity.

A Bibliometric Analysis of Metabolic Reprogramming in the Tumor Microenvironment From 2003 to 2022

BACKGROUND

Despite considerable progress in cancer immunotherapy, it is not available for many patients. Resistance to immune checkpoint blockers arises from the intricate interactions between cancer and its microenvironment. Metabolic reprogramming in tumor and immune cells in the tumor microenvironment (TME) influences anti-tumor immune responses by remodeling the immune microenvironment. Metabolic reprogramming has emerged as an important hallmark of tumorigenesis. However, few studies have focused on the TME and metabolic reprogramming. Therefore, we aimed to explore the current research status and popular topics in TME-related metabolic reprogramming over a 20 years using a bibliometric approach.

METHODS

Studies focusing on metabolic reprogramming and TME were searched using the Web of Science Core Collection database. Bibliometric and visual analyses of the articles and reviews were performed using Bibliometrix, VOSviewer, and CiteSpace.

RESULTS

In total, 4726 articles published between 2003 and 2022 were selected. The number of publications and citations has increased annually. Cooperation network analysis indicated that the United States holds the foremost position in metabolic reprogramming and TME research with the highest volume of publications and citations, thus exerting the greatest influence. Among these institutions, Fudan University displayed the highest level of productivity. Frontiers in Immunology showed the highest degree of productivity in this field. Ho Ping-Chih made the most article contributions, and Pearce Edward J. was the most co-cited author. Four clusters were obtained after a cluster analysis of the authors' keywords: TME, metabolic reprogramming, immunometabolism, and immunity. Immunometabolism, glycolysis, immune cells, and tumor-associated macrophages are relatively recent keywords that have attracted increasing attention.

CONCLUSIONS

A comprehensive landscape of advancements in metabolic reprogramming and the TME was evaluated, which provided crucial information for scholars to further advance this promising field. Further research should explore new topics related to immunometabolism in the TME using a transdisciplinary approach.

Acyl-CoA Synthetase Medium-Chain Family Member 5-Mediated Fatty Acid Metabolism Dysregulation Promotes the Progression of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most common primary liver cancer, with high incidence and mortality worldwide. Despite diagnostic and therapeutic advancements, HCC remains poorly responsive to treatment, with a poor prognosis. Understanding the molecular mechanisms driving HCC is crucial for developing effective therapies. Emerging evidence indicates that dysregulated fatty acid metabolism contributes to HCC. Acyl-CoA medium-chain synthetase 5 (ACSM5), involved in fatty acid metabolism, is down-regulated in HCC; however, its role is not well understood. In this study, we analyzed ACSM5 expression in HCC patient samples and cell lines. Using newly established ACSM5-overexpressing HCC cell lines, Huh7-ACSM5 and Hepa1-6-ACSM5, we investigated the effects and regulatory mechanisms of ACSM5. Our results showed that ACSM5 was significantly down-regulated in HCC tumor tissues compared with nontumor tissues. ACSM5 expression was regulated by DNA methylation, with a DNMT1 inhibitor effectively increasing ACSM5 expression and reducing promoter region methylation. Overexpression of ACSM5 in Huh7 cells reduced fatty acid accumulation, decreased cell proliferation, migration, and invasion in vitro, and inhibited tumor growth in mouse xenografts. Furthermore, ACSM5 overexpression also decreased STAT3 phosphorylation, subsequently affecting downstream cytokine TGFB and FGF12 mRNA levels. Our findings suggest that ACSM5 down-regulation contributes to HCC progression, providing insights into its oncogenic role and highlighting its potential as a biomarker and therapeutic target for HCC.

Metabolic adaptations in prostate cancer

Prostate cancer is one of the most commonly diagnosed cancers in men and is a major cause of cancer-related deaths worldwide. Among the molecular processes that contribute to this disease, the weight of metabolism has been placed under the limelight in recent years. Tumours exhibit metabolic adaptations to comply with their biosynthetic needs. However, metabolites also play an important role in supporting cell survival in challenging environments or remodelling the tumour microenvironment, thus being recognized as a hallmark in cancer. Prostate cancer is uniquely driven by androgen receptor signalling, and this knowledge has also influenced the paths of cancer metabolism research. This review provides a comprehensive perspective on the metabolic adaptations that support prostate cancer progression beyond androgen signalling, with a particular focus on tumour cell intrinsic and extrinsic pathways.

Leveraging altered lipid metabolism in treating B cell malignancies

B cell malignancies, comprising over 80 heterogeneous blood cancers, pose significant prognostic challenges due to intricate oncogenic signaling. Emerging evidence emphasizes the pivotal role of disrupted lipid metabolism in the development of these malignancies. Variations in lipid species, such as phospholipids, cholesterol, sphingolipids, and fatty acids, are widespread across B cell malignancies, contributing to uncontrolled cell proliferation and survival. Phospholipids play a crucial role in initial signaling cascades leading to B cell activation and malignant transformation through constitutive B cell receptor (BCR) signaling. Dysregulated cholesterol and sphingolipid homeostasis support lipid raft integrity, crucial for propagating oncogenic signals. Sphingolipids impact malignant B cell stemness, proliferation, and survival, while glycosphingolipids in lipid rafts modulate BCR activation. Additionally, cancer cells enhance fatty acid-related processes to meet heightened metabolic demands. In obese individuals, the obesity-derived lipids and adipokines surrounding adipocytes rewire lipid metabolism in malignant B cells, evading cytotoxic therapies. Genetic drivers such as MYC translocations also intrinsically alter lipid metabolism in malignant B cells. In summary, intrinsic and extrinsic factors converge to reprogram lipid metabolism, fostering aggressive phenotypes in B cell malignancies. Therefore, targeting altered lipid metabolism has translational potential for improving risk stratification and clinical management of diverse B cell malignancy subtypes.

Immunometabolism of CD8+ T cell differentiation in cancer

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

Phosphoglycerate mutase regulates Treg differentiation through control of serine synthesis and one-carbon metabolism

The differentiation and suppressive functions of regulatory CD4 T cells (Tregs) are supported by a broad array of metabolic changes, providing potential therapeutic targets for immune modulation. In this study, we focused on the regulatory role of glycolytic enzymes in Tregs and identified phosphoglycerate mutase (PGAM) as being differentially overexpressed in Tregs and associated with a highly suppressive phenotype. Pharmacologic or genetic inhibition of PGAM reduced Treg differentiation and suppressive function while reciprocally inducing markers of a pro-inflammatory, T helper 17 (Th17)-like state. The regulatory role of PGAM was dependent on the contribution of 3-phosphoglycerate (3PG), the PGAM substrate, to de novo serine synthesis. Blocking de novo serine synthesis from 3PG reversed the effect of PGAM inhibition on Treg polarization, while exogenous serine directly inhibited Treg polarization. Additionally, altering serine levels in vivo with a serine/glycine-free diet increased peripheral Tregs and attenuated autoimmunity in a murine model of multiple sclerosis. Mechanistically, we found that serine limits Treg polarization by contributing to one-carbon metabolism and methylation of Treg-associated genes. Inhibiting one-carbon metabolism increased Treg polarization and suppressive function both in vitro and in vivo in a murine model of autoimmune colitis. Our study identifies a novel physiologic role for PGAM and highlights the metabolic interconnectivity between glycolysis, serine synthesis, one-carbon metabolism, and epigenetic regulation of Treg differentiation and suppressive function.

Metabolic Plasticity of Regulatory T Cells in Health and Autoimmunity

Immunometabolism has been demonstrated to control immune tolerance and the pathogenic events leading to autoimmunity. Compelling experimental evidence also suggests that intracellular metabolic programs influence differentiation, phenotype, proliferation, and effector functions of anti-inflammatory CD4+CD25+Foxp3+ regulatory T (Treg) cells. Indeed, alterations in intracellular metabolism associate with quantitative and qualitative impairments of Treg cells in several pathological conditions. In this review, we summarize the most recent advances linking how metabolic pathways control Treg cell homeostasis and their alterations occurring in autoimmunity. Also, we analyze how metabolic manipulations could be employed to restore Treg cell frequency and function with the aim to create novel therapeutic opportunities to halt immune-mediated disorders.

Intersection of Immunology and Metabolism in Myocardial Disease

Immunometabolism is an emerging field at the intersection of immunology and metabolism. Immune cell activation plays a critical role in the pathogenesis of cardiovascular diseases and is integral for regeneration during cardiac injury. We currently possess a limited understanding of the processes governing metabolic interactions between immune cells and cardiomyocytes. The impact of this intercellular crosstalk can manifest as alterations to the steady state flux of metabolites and impact cardiac contractile function. Although much of our knowledge is derived from acute inflammatory response, recent work emphasizes heterogeneity and flexibility in metabolism between cardiomyocytes and immune cells during pathological states, including ischemic, cardiometabolic, and cancer-associated disease. Metabolic adaptation is crucial because it influences immune cell activation, cytokine release, and potential therapeutic vulnerabilities. This review describes current concepts about immunometabolic regulation in the heart, focusing on intercellular crosstalk and intrinsic factors driving cellular regulation. We discuss experimental approaches to measure the cardio-immunologic crosstalk, which are necessary to uncover unknown mechanisms underlying the immune and cardiac interface. Deeper insight into these axes holds promise for therapeutic strategies that optimize cardioimmunology crosstalk for cardiac health.

Resonance of fatty acid metabolism and immune infiltration in anti-PD-1 monotherapy for breast cancer

The interaction between tumor fatty acid metabolism and immune microenvironment is a novel topic in oncology research, and the relationship of lipid-derived factors with immune editing in tumor is unclear. The breast cancer samples from the TCGA database were used as the training set, and samples from GSE42568 were employed as the validation set for constructing a model to identify a signature associated with fatty acid metabolism through Lasso Cox regression. And the changes in immune related signatures and risk score before and after anti-PD-1 monotherapy were caught by the differential analysis in GSE225078. A 14-gene prognostic risk scoring model identifying by fatty acid metabolism relevant signature was conducted, and the high risk group had shorter overall survival and progression free survival than low risk group. Many metabolism-related pathways were enriched in the high risk group, and many immune-related pathways were enriched in low risk group. The crucial differentially expressed genes between the high/low risk groups, CYP4F8 and CD52, were found to be strongly associated with SUCLA2 and ACOT4 of 14-gene model, and strongly related to immune infiltration. Immune related signatures, fatty acid metabolism-risk score and the expression level of ALDH1A1 (in 14-gene-model) changed after anti-PD-1 monotherapy. And the mice model results also showed anti-PD-1 mAb could significantly reduce the expression level of ALDH1A1 (p < 0.01). These results brought up the crosstalk between immune components and fatty acid metabolism in breast cancer microenvironment, which provided a new possibility of targeting fatty acid metabolism for combination therapy in breast cancer immunotherapy.

Tanshinone IIA acts as a regulator of lipogenesis to overcome osimertinib acquired resistance in lung cancer

Osimertinib is a novel epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), acting as the first-line medicine for advanced EGFR-mutated NSCLC. Recently, the acquired resistance to osimertinib brings great challenges to the advanced treatment. Therefore, it is in urgent need to find effective strategy to overcome osimertinib acquired resistance. Here, we demonstrated that SREBP pathway-driven lipogenesis was a key mediator to promote osimertinib acquired resistance, and firstly found Tanshinone IIA (Tan IIA), a natural pharmacologically active constituent isolated from Salvia miltiorrhiza, could overcome osimertinib-acquired resistance in vitro and in vivo via inhibiting SREBP pathway-mediated lipid lipogenesis by using LC-MS based cellular lipidomics analysis, quantitative real-time PCR (qRT-PCR) analysis, western blotting analysis, flow cytometry, small interfering RNAs transfection, and membrane fluidity assay et al. The results showed that SREBP1/2-driven lipogenesis was highly activated in osimertinib acquired resistant NSCLC cells, while knockdown or inhibition of SREBP1/2 could restore the sensitivity of NSCLC to osimertinib via altered the proportion of saturated phospholipids and unsaturated phospholipids in osimertinib acquired-resistant cells. Furthermore, Tanshinone IIA (Tan IIA) could reverse the acquired resistance to osimertinib in lung cancer. Mechanically, Tan IIA inhibited SREBP signaling mediated lipogenesis, changed the profiles of saturated phospholipids and unsaturated phospholipids, and thus promoted osimertinib acquired resistant cancer cells to be attacked by oxidative stress-induced damage and reduce the cell membrane fluidity. The reversal effect of Tan IIA on osimertinib acquired resistant NSCLC cells was also confirmed in vivo, which is helpful for the development of strategies to reverse osimertinib acquired resistance.

Emerging targets in lipid metabolism for cancer therapy

Cancer cells perturb lipid metabolic pathways for a variety of pro-tumorigenic functions, and deregulated cellular metabolism is a hallmark of cancer cells. Although alterations in lipid metabolism in cancer cells have been appreciated for over 20 years, there are no FDA-approved cancer treatments that target lipid-related pathways. Recent advances pertaining to cancer cell fatty acid synthesis (FAS), desaturation, and uptake, microenvironmental and dietary lipids, and lipid metabolism of tumor-infiltrating immune cells have illuminated promising clinical applications for targeting lipid metabolism. This review highlights emerging pathways and targets for tumor lipid metabolism that may soon impact clinical treatment.

Nanomaterials in modulating tumor-associated macrophages and enhancing immunotherapy

Tumor-associated macrophages (TAMs) are predominantly present in the tumor microenvironment (TME) and play a crucial role in shaping the efficacy of tumor immunotherapy. These TAMs primarily exhibit a tumor-promoting M2-like phenotype, which is associated with the suppression of immune responses and facilitation of tumor progression. Interestingly, recent research has highlighted the potential of repolarizing TAMs from an M2 to a pro-inflammatory M1 status-a shift that has shown promise in impeding tumor growth and enhancing immune responsiveness. This concept is particularly intriguing as it offers a new dimension to cancer therapy by targeting the tumor microenvironment, which is a significant departure from traditional approaches that focus solely on tumor cells. However, the clinical application of TAM-modulating agents is often challenged by issues such as insufficient tumor accumulation and off-target effects, limiting their effectiveness and safety. In this regard, nanomaterials have emerged as a novel solution. They serve a dual role: as delivery vehicles that can enhance the accumulation of therapeutic agents in the tumor site and as TAM-modulators. This dual functionality of nanomaterials is a significant advancement as it addresses the key limitations of current TAM-modulating strategies and opens up new avenues for more efficient and targeted therapies. This review provides a comprehensive overview of the latest mechanisms and strategies involving nanomaterials in modulating macrophage polarization within the TME. It delves into the intricate interactions between nanomaterials and macrophages, elucidating how these interactions can be exploited to drive macrophage polarization towards a phenotype that is more conducive to anti-tumor immunity. Additionally, the review explores the burgeoning field of TAM-associated nanomedicines in combination with tumor immunotherapy. This combination approach is particularly promising as it leverages the strengths of both nanomedicine and immunotherapy, potentially leading to synergistic effects in combating cancer.

Metabolic rewiring and communication in cancer immunity

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

Fatostatin promotes anti-tumor immunity by reducing SREBP2 mediated cholesterol metabolism in tumor-infiltrating T lymphocytes

Aberrant lipid metabolism impacts intratumoral T cell-mediated immune response and tumor growth. Fatostatin functions as an inhibitor of sterol regulatory element binding protein (SREBP) activation. However, the complex effects of fatostatin on cholesterol metabolism in the tumor microenvironment (TME) and its influence on T cell anti-tumor immunity remain unclear. In this study, fatostatin effectively suppressed B16 melanoma, MC38 colon cancer, and Lewis lung cancer (LLC) transplanted tumor growth in immunocompetent mice by reducing SREBPs-mediated lipid metabolism, especially cholesterol levels. Mechanistically, fatostatin decreased intracellular cholesterol accumulation and inhibited X-box binding protein 1 (XBP1)-mediated endoplasmic reticulum (ER) stress, reducing Treg cells and alleviating CD8+ T cell exhaustion in the TME, exerting anti-tumor activity. Nevertheless， this effect was impaired in immunodeficient nude mice, suggesting fatostatin's anti-tumor efficacy in transplanted tumors partly relies on T cell-mediated anti-tumor immunity. Our study highlights SREBP2-mediated cholesterol metabolism as a potential strategy for anti-tumor immunotherapy, and confirms fatostatin's promise in tumor immunotherapy.

Abrogation and homeostatic restoration of IgE responses by a universal IgE allergy CTL vaccine-The three signal self/non-self/self (S/NS/S) theory

Natural IgE cytotoxic peptides (nECPs), which are derived from the constant domain of the heavy chain of human IgE producing B cells via endoplasmic reticulum (ER) stress, are decorated onto MHC class 1a molecules (MHCIa) as unique biomarkers for CTL (cytotoxic T lymphocyte)-mediated immune surveillance. Human IgE exhibits only one isotype and lacks polymorphisms; IgE is pivotal in mediating diverse, allergen-specific allergies. Therefore, by disrupting self-IgE tolerance via costimulation, the CTLs induced by nECPs can serve as universal allergy vaccines (UAVs) in humans to dampen IgE production mediated by diverse allergen-specific IgE-secreting B cells and plasma cells expressing surface nECP-MHCIa as targets. The study herein has enabled the identification of nECPs, A32 and SP-1/SP-2 nonameric natural peptides produced through the correspondence principle. Vaccination using nECP induced nECP-specific CTL that profoundly suppressed human IgE production in vitro as well as chimeric human IgE production in human IgE/HLA-A2.01/HLA-B7.02 triple transgenic rodents. Furthermore, nECP-tetramer-specific CTLs were found to be converted into CD4 Tregs that restored IgE competence via the homeostatic principle, mediatepred by SREBP-1c suppressed DCs. Thus, nECPs showed causal efficacy and safety as UAVs for treating categorically type I hypersensitivity IgE-mediated allergies. The applied vaccination concept presented provides the foundation to unify, integrate through a singular class of tetramer-specific TCR clonotypes for regulaing human IgE production. The three signal theory pertains to mechanisms of three cells underlying central tolerance (S), breaking self tolerance (NS) and regaining peripheral tolerance (S) via homeostasis concerning nECP as an efficacious and safe UAV to treat type I IgE-mediated hypersensitivity. The three signal theory impirically extended, may be heuritic for immuno-regulation of adaptive immune repertoire in general.

Metabolite-derived damage-associated molecular patterns in immunological diseases

Damage-associated molecular patterns (DAMPs) are typically derived from the endogenous elements of necrosis cells and can trigger inflammatory responses by activating DAMPs-sensing receptors on immune cells. Failure to clear DAMPs may lead to persistent inflammation, thereby contributing to the pathogenesis of immunological diseases. This review focuses on a newly recognized class of DAMPs derived from lipid, glucose, nucleotide, and amino acid metabolic pathways, which are then termed as metabolite-derived DAMPs. This review summarizes the reported molecular mechanisms of these metabolite-derived DAMPs in exacerbating inflammation responses, which may attribute to the pathology of certain types of immunological diseases. Additionally, this review also highlights both direct and indirect clinical interventions that have been explored to mitigate the pathological effects of these DAMPs. By summarizing our current understanding of metabolite-derived DAMPs, this review aims to inspire future thoughts and endeavors on targeted medicinal interventions and the development of therapies for immunological diseases.

Regulatory T cell-mediated immunosuppression orchestrated by cancer: towards an immuno-genomic paradigm for precision medicine

Accumulating evidence indicates that aberrant signalling stemming from genetic abnormalities in cancer cells has a fundamental role in their evasion of antitumour immunity. Immune escape mechanisms include enhanced expression of immunosuppressive molecules, such as immune-checkpoint proteins, and the accumulation of immunosuppressive cells, including regulatory T (Treg) cells, in the tumour microenvironment. Therefore, Treg cells are key targets for cancer immunotherapy. Given that therapies targeting molecules predominantly expressed by Treg cells, such as CD25 or GITR, have thus far had limited antitumour efficacy, elucidating how certain characteristics of cancer, particularly genetic abnormalities, influence Treg cells is necessary to develop novel immunotherapeutic strategies. Hence, Treg cell-targeted strategies based on the particular characteristics of cancer in each patient, such as the combination of immune-checkpoint inhibitors with molecularly targeted agents that disrupt the immunosuppressive networks mediating Treg cell recruitment and/or activation, could become a new paradigm of cancer therapy. In this Review, we discuss new insights on the mechanisms by which cancers generate immunosuppressive networks that attenuate antitumour immunity and how these networks confer resistance to cancer immunotherapy, with a focus on Treg cells. These insights lead us to propose the concept of 'immuno-genomic precision medicine' based on specific characteristics of cancer, especially genetic profiles, that correlate with particular mechanisms of tumour immune escape and might, therefore, inform the optimal choice of immunotherapy for individual patients.

Cellular metabolism regulates the differentiation and function of T-cell subsets

T cells are an important component of adaptive immunity and protect the host from infectious diseases and cancers. However, uncontrolled T cell immunity may cause autoimmune disorders. In both situations, antigen-specific T cells undergo clonal expansion upon the engagement and activation of antigens. Cellular metabolism is reprogrammed to meet the increase in bioenergetic and biosynthetic demands associated with effector T cell expansion. Metabolites not only serve as building blocks or energy sources to fuel cell growth and expansion but also regulate a broad spectrum of cellular signals that instruct the differentiation of multiple T cell subsets. The realm of immunometabolism research is undergoing swift advancements. Encapsulating all the recent progress within this concise review in not possible. Instead, our objective is to provide a succinct introduction to this swiftly progressing research, concentrating on the metabolic intricacies of three pivotal nutrient classes-lipids, glucose, and amino acids-in T cells. We shed light on recent investigations elucidating the roles of these three groups of metabolites in mediating the metabolic and immune functions of T cells. Moreover, we delve into the prospect of "editing" metabolic pathways within T cells using pharmacological or genetic approaches, with the aim of synergizing this approach with existing immunotherapies and enhancing the efficacy of antitumor and antiinfection immune responses.

Principles and therapeutic applications of adaptive immunity

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

Lipid metabolism in tumor-infiltrating regulatory T cells: perspective to precision immunotherapy

Regulatory T cells (Tregs) are essential to the negative regulation of the immune system, as they avoid excessive inflammation and mediate tumor development. The abundance of Tregs in tumor tissues suggests that Tregs may be eliminated or functionally inhibited to stimulate antitumor immunity. However, immunotherapy targeting Tregs has been severely hampered by autoimmune diseases due to the systemic elimination of Tregs. Recently, emerging studies have shown that metabolic regulation can specifically target tumor-infiltrating immune cells, and lipid accumulation in TME is associated with immunosuppression. Nevertheless, how Tregs actively regulate metabolic reprogramming to outcompete effector T cells (Teffs), and how lipid metabolic reprogramming contributes to the immunomodulatory capacity of Tregs have not been fully discussed. This review will discuss the physiological processes by which lipid accumulation confers a metabolic advantage to tumor-infiltrating Tregs (TI-Tregs) and amplifies their immunosuppressive functions. Furthermore, we will provide a summary of the driving effects of various metabolic regulators on the metabolic reprogramming of Tregs. Finally, we propose that targeting the lipid metabolism of TI-Tregs could be efficacious either alone or in conjunction with immune checkpoint therapy.

Cancer immunometabolism: advent, challenges, and perspective

For decades, great strides have been made in the field of immunometabolism. A plethora of evidence ranging from basic mechanisms to clinical transformation has gradually embarked on immunometabolism to the center stage of innate and adaptive immunomodulation. Given this, we focus on changes in immunometabolism, a converging series of biochemical events that alters immune cell function, propose the immune roles played by diversified metabolic derivatives and enzymes, emphasize the key metabolism-related checkpoints in distinct immune cell types, and discuss the ongoing and upcoming realities of clinical treatment. It is expected that future research will reduce the current limitations of immunotherapy and provide a positive hand in immune responses to exert a broader therapeutic role.

Dietary elaidic acid boosts tumoral antigen presentation and cancer immunity via ACSL5

Immunomodulatory effects of long-chain fatty acids (LCFAs) and their activating enzyme, acyl-coenzyme A (CoA) synthetase long-chain family (ACSL), in the tumor microenvironment remain largely unknown. Here, we find that ACSL5 functions as an immune-dependent tumor suppressor. ACSL5 expression sensitizes tumors to PD-1 blockade therapy in vivo and the cytotoxicity mediated by CD8+ T cells in vitro via regulation of major histocompatibility complex class I (MHC-I)-mediated antigen presentation. Through screening potential substrates for ACSL5, we further identify that elaidic acid (EA), a trans LCFA that has long been considered harmful to human health, phenocopies to enhance MHC-I expression. EA supplementation can suppress tumor growth and sensitize PD-1 blockade therapy. Clinically, ACSL5 expression is positively associated with improved survival in patients with lung cancer, and plasma EA level is also predictive for immunotherapy efficiency. Our findings provide a foundation for enhancing immunotherapy through either targeting ACSL5 or metabolic reprogramming of antigen presentation via dietary EA supplementation.

Impact of ACSL4 on the prognosis of hepatocellular carcinoma: Association with cancer-associated fibroblasts and the tumour immune microenvironment

BACKGROUND & AIMS

Recently, the association between hepatocellular carcinoma (HCC) and ferroptosis has been the focus of much attention. The expression of long chain fatty acyl-CoA ligase 4 (ACSL4), a marker of ferroptosis, in tumour tissue is related to better prognosis in various cancers. In HCC, ACSL4 expression indicates poor prognosis and is related to high malignancy. However, the mechanism remains to be fully understood.

METHODS

We retrospectively enrolled 358 patients with HCC who had undergone hepatic resection. Immunohistochemistry (IHC) for ACSL4 was performed. Factors associated with ASCL4 expression were investigated by spatial transcriptome analysis, and the relationships were investigated by IHC. The association between ACSL4 and the tumour immune microenvironment was examined in a public dataset and investigated by IHC.

RESULTS

Patients were divided into ACSL4-positive (n = 72, 20.1%) and ACSL4-negative (n = 286, 79.9%) groups. ACSL4 positivity was significantly correlated with higher α-fetoprotein (p = .0180) and more histological liver fibrosis (p = .0014). In multivariate analysis, ACSL4 positivity was an independent prognostic factor (p < .0001). Spatial transcriptome analysis showed a positive correlation between ACSL4 and cancer-associated fibroblasts; this relationship was confirmed by IHC. Evaluation of a public dataset showed the correlation between ACSL4 and exhausted tumour immune microenvironment; this relationship was also confirmed by IHC.

CONCLUSION

ACSL4 is a prognostic factor in HCC patients and its expression was associated with cancer-associated fibroblasts and anti-tumour immunity.

Effects of dietary intervention on human diseases: molecular mechanisms and therapeutic potential

Diet, serving as a vital source of nutrients, exerts a profound influence on human health and disease progression. Recently, dietary interventions have emerged as promising adjunctive treatment strategies not only for cancer but also for neurodegenerative diseases, autoimmune diseases, cardiovascular diseases, and metabolic disorders. These interventions have demonstrated substantial potential in modulating metabolism, disease trajectory, and therapeutic responses. Metabolic reprogramming is a hallmark of malignant progression, and a deeper understanding of this phenomenon in tumors and its effects on immune regulation is a significant challenge that impedes cancer eradication. Dietary intake, as a key environmental factor, can influence tumor metabolism. Emerging evidence indicates that dietary interventions might affect the nutrient availability in tumors, thereby increasing the efficacy of cancer treatments. However, the intricate interplay between dietary interventions and the pathogenesis of cancer and other diseases is complex. Despite encouraging results, the mechanisms underlying diet-based therapeutic strategies remain largely unexplored, often resulting in underutilization in disease management. In this review, we aim to illuminate the potential effects of various dietary interventions, including calorie restriction, fasting-mimicking diet, ketogenic diet, protein restriction diet, high-salt diet, high-fat diet, and high-fiber diet, on cancer and the aforementioned diseases. We explore the multifaceted impacts of these dietary interventions, encompassing their immunomodulatory effects, other biological impacts, and underlying molecular mechanisms. This review offers valuable insights into the potential application of these dietary interventions as adjunctive therapies in disease management.

Anti-metabolic agent pegaspargase plus PD-1 antibody sintilimab for first-line treatment in advanced natural killer T cell lymphoma

Natural killer T cell lymphoma (NKTCL) is highly aggressive, with advanced stage patients poorly responding to intensive chemotherapy. To explore effective and safe treatment for newly diagnosed advanced stage NKTCL, we conducted a phase II study of anti-metabolic agent pegaspargase plus PD-1 antibody sintilimab (NCT04096690). Twenty-two patients with a median age of 51 years (range, 24-74) were enrolled and treated with induction treatment of pegaspargase 2500 IU/m2 intramuscularly on day 1 and sintilimab 200 mg intravenously on day 2 for 6 cycles of 21 days, followed by maintenance treatment of sintilimab 200 mg for 28 cycles of 21 days. The complete response and overall response rate after induction treatment were 59% (95%CI, 43-79%) and 68% (95%CI, 47-84%), respectively. With a median follow-up of 30 months, the 2 year progression-free and overall survival rates were 68% (95%CI, 45-83%) and 86% (95%CI, 63-95%), respectively. The most frequently grade 3/4 adverse events were neutropenia (32%, n = 7) and hypofibrinogenemia (18%, n = 4), which were manageable and led to no discontinuation of treatment. Tumor proportion score of PD-L1, peripheral blood high-density lipoprotein cholesterol, and apolipoprotein A-I correlated with good response, while PD-1 on tumor infiltrating lymphocytes and peripheral Treg cells with poor response to pegaspargase plus sintilimab treatment. In conclusion, the chemo-free regimen pegaspargase plus sintilimab was effective and safe in newly diagnosed, advanced stage NKTCL. Dysregulated lipid profile and immunosuppressive signature contributed to treatment resistance, providing an alternative therapeutic approach dual targeting fatty acid metabolism and CTLA-4 in NKTCL.

Nutrients: Signal 4 in T cell immunity

T cells are integral in mediating adaptive immunity to infection, autoimmunity, and cancer. Upon immune challenge, T cells exit from a quiescent state, followed by clonal expansion and effector differentiation. These processes are shaped by three established immune signals, namely antigen stimulation (Signal 1), costimulation (Signal 2), and cytokines (Signal 3). Emerging findings reveal that nutrients, including glucose, amino acids, and lipids, are crucial regulators of T cell responses and interplay with Signals 1-3, highlighting nutrients as Signal 4 to license T cell immunity. Here, we first summarize the functional importance of Signal 4 and the underlying mechanisms of nutrient transport, sensing, and signaling in orchestrating T cell activation and quiescence exit. We also discuss the roles of nutrients in programming T cell differentiation and functional fitness and how nutrients can be targeted to improve disease therapy. Understanding how T cells respond to Signal 4 nutrients in microenvironments will provide insights into context-dependent functions of adaptive immunity and therapeutic interventions.

Metabolic interplay: tumor macrophages and regulatory T cells

The tumor microenvironment (TME) contains a complex cellular ecosystem where cancer, stromal, vascular, and immune cells interact. Macrophages and regulatory T cells (Tregs) are critical not only for maintaining immunological homeostasis and tumor growth but also for monitoring the functional states of other immune cells. Emerging evidence reveals that metabolic changes in macrophages and Tregs significantly influence their pro-/antitumor functions through the regulation of signaling cascades and epigenetic reprogramming. Hence, they are increasingly recognized as therapeutic targets in cancer immunotherapy. Specific metabolites in the TME may also affect their pro-/antitumor functions by intervening with the metabolic machinery. We discuss how metabolites influence the immunosuppressive phenotypes of tumor-associated macrophages (TAMs) and Tregs. We then describe how TAMs and Tregs, independently or collaboratively, utilize metabolic mechanisms to suppress the activity of CD8+ T cells. Finally, we highlight promising metabolic interventions that can improve the outcome of current cancer therapies.

Targeting JMJD1C to selectively disrupt tumor Treg cell fitness enhances antitumor immunity

Regulatory T (Treg) cells are critical for immune tolerance but also form a barrier to antitumor immunity. As therapeutic strategies involving Treg cell depletion are limited by concurrent autoimmune disorders, identification of intratumoral Treg cell-specific regulatory mechanisms is needed for selective targeting. Epigenetic modulators can be targeted with small compounds, but intratumoral Treg cell-specific epigenetic regulators have been unexplored. Here, we show that JMJD1C, a histone demethylase upregulated by cytokines in the tumor microenvironment, is essential for tumor Treg cell fitness but dispensable for systemic immune homeostasis. JMJD1C deletion enhanced AKT signals in a manner dependent on histone H3 lysine 9 dimethylation (H3K9me2) demethylase and STAT3 signals independently of H3K9me2 demethylase, leading to robust interferon-γ production and tumor Treg cell fragility. We have also developed an oral JMJD1C inhibitor that suppresses tumor growth by targeting intratumoral Treg cells. Overall, this study identifies JMJD1C as an epigenetic hub that can integrate signals to establish tumor Treg cell fitness, and we present a specific JMJD1C inhibitor that can target tumor Treg cells without affecting systemic immune homeostasis.

Fatty acid synthase (FASN) signalome: A molecular guide for precision oncology

The initial excitement generated more than two decades ago by the discovery of drugs targeting fatty acid synthase (FASN)-catalyzed de novo lipogenesis for cancer therapy was short-lived. However, the advent of the first clinical-grade FASN inhibitor (TVB-2640; denifanstat), which is currently being studied in various phase II trials, and the exciting advances in understanding the FASN signalome are fueling a renewed interest in FASN-targeted strategies for the treatment and prevention of cancer. Here, we provide a detailed overview of how FASN can drive phenotypic plasticity and cell fate decisions, mitochondrial regulation of cell death, immune escape and organ-specific metastatic potential. We then present a variety of FASN-targeted therapeutic approaches that address the major challenges facing FASN therapy. These include limitations of current FASN inhibitors and the lack of precision tools to maximize the therapeutic potential of FASN inhibitors in the clinic. Rethinking the role of FASN as a signal transducer in cancer pathogenesis may provide molecularly driven strategies to optimize FASN as a long-awaited target for cancer therapeutics.

Cinobufacini injection delays hepatocellular carcinoma progression by regulating lipid metabolism via SREBP1 signaling pathway and affecting macrophage polarization

ETHNOPHARMACOLOGICAL RELEVANCE

Cinobufacini injection, an aqueous extract of the toad, is a commonly used anti-tumor animal herbal medicine in clinical practice. It has the effects of detoxifying, reducing swelling, and relieving pain.

AIMS OF THE STUDY

To investigate the effects of Cinobufacini injection on hepatocellular carcinoma progression by regulating lipid metabolism and macrophage polarization in the tumor microenvironment and to identify the potential molecular mechanisms.

MATERIALS AND METHODS

To establish the axillary transplantation tumor model of hepatocellular carcinoma Hepa1-6 in C57BL/6 mice, and to evaluate the inhibitory effect of Cinobufacini injection on hepatocellular carcinoma in vivo as well as drug delivery security. Combined metabolomics and transcriptomics analysis of the effect of Cinobufagin Injection on tumor microenvironment. An in vitro mouse co-culture model of peritoneal macrophages and Hepa1-6 cells was established to research the effects of Cinobufacini injection on macrophage polarization, hepatocellular carcinoma cell growth, migration, and changes in lipid metabolism. Cinobufacini injection inhibition of the AMPK/SREBP1/FASN signaling pathway regulating cholesterol metabolism and affecting macrophage polarization was examined using qRT-PCR, lentiviral transfection, immunofluorescence, and Western blot.

RESULT

In vivo experiments demonstrated that Cinobufacini injection treatment significantly inhibited the growth of Hepa1-6 hepatomas, along with a reduction in cholesterol content and a decrease in the percentage of M2 macrophages in tumor tissue. In vitro, we found that Cinobufacini injection inhibits IL-4-induced M2 macrophage polarization, reduces the cholesterol content of Hepa1-6 cells in a co-culture system, and inhibits the promotion of hepatocellular carcinoma cells by M2 macrophages. In addition, successful overexpression of SREBP1 in Hepa1-6 cells showed more pronounced cellular activity whereas Cinobufacini injection inhibited this change and reduced intracellular lipid levels.

CONCLUSION

Cinobufacini injection inhibits cholesterol synthesis within the tumor microenvironment via the AMPK/SERBP1/FASN signaling pathway, which in turn blocks the M2 polarization of macrophages, leading to the weakening of hepatocellular carcinoma growth and migration, and the promotion of its apoptosis. Our findings provide an important Introduction to understanding the molecular mechanism of Cinobufacini injection's anticancer activity and provide reliable theoretical and experimental support for its clinical application.

Fatty acid metabolism-related lncRNAs are potential biomarkers for survival prediction in clear cell renal cell carcinoma

Metabolic reprogramming of energy is a newly recognized characteristic of cancer. In our current investigation, we examined the possible predictive importance of long noncoding RNAs (lncRNAs) associated to fatty acid metabolism in clear cell renal cell carcinoma (ccRCC). We conducted an analysis of the gene expression data obtained from patients diagnosed with ccRCC using the Cancer Genome Atlas (TCGA) database and the ArrayExpress database. We performed a screening to identify lncRNAs that are differentially expressed in fatty acid metabolism. Based on these findings, we developed a prognostic risk score model using these fatty acid metabolism-related lncRNAs. We then validated this model using Cox regression analysis, Kaplan-Meier survival analysis, and principal-component analysis (PCA). Furthermore, the prognostic risk score model was successfully validated using both the TCGA cohort and the E-MTAB-1980 cohort. We utilized gene set variation analysis (GSVA) and gene set enrichment analysis (GSEA) to determine the correlation between fatty acid metabolism and the PPAR signaling pathway in patients with ccRCC at various clinical stages and prognoses. We have discovered compelling evidence of the interaction between immune cells in the tumor microenvironment and tumor cells, which leads to immune evasion and resistance to drugs. This was achieved by the utilization of advanced techniques such as the CIBERSORT method, ESTIMATE R package, ssGSEA algorithm, and TIMER database exploration. Ultimately, we have established a network of competing endogenous RNA (ceRNA) that is related to fatty acid metabolism. The findings of our study suggest that medicines focused on fatty acid metabolism could be clinically significant for individuals with ccRCC. The utilization of this risk model, which is centered around the lncRNAs associated with fatty acid metabolism, could potentially provide valuable prognostic information and hold immunotherapeutic implications for patients with ccRCC.

Reprogramming of regulatory T cells in inflammatory tumor microenvironment: can it become immunotherapy turning point?

Overcoming the immunosuppressive tumor microenvironment and identifying widely used immunosuppressants with minimal side effects are two major challenges currently hampering cancer immunotherapy. Regulatory T cells (Tregs) are present in almost all cancer tissues and play an important role in preserving autoimmune tolerance and tissue homeostasis. The tumor inflammatory microenvironment causes the reprogramming of Tregs, resulting in the conversion of Tregs to immunosuppressive phenotypes. This process ultimately facilitates tumor immune escape or tumor progression. However, current systemic Treg depletion therapies may lead to severe autoimmune toxicity. Therefore, it is crucial to understand the mechanism of Treg reprogramming and develop immunotherapies that selectively target Tregs within tumors. This article provides a comprehensive review of the potential mechanisms involved in Treg cell reprogramming and explores the application of Treg cell immunotherapy. The interference with reprogramming pathways has shown promise in reducing the number of tumor-associated Tregs or impairing their function during immunotherapy, thereby improving anti-tumor immune responses. Furthermore, a deeper understanding of the mechanisms that drive Treg cell reprogramming could reveal new molecular targets for future treatments.

Metabolic advantages of regulatory T cells dictated by cancer cells

Cancer cells employ glycolysis for their survival and growth (the "Warburg effect"). Consequently, surrounding cells including immune cells in the tumor microenvironment (TME) are exposed to hypoglycemic, hypoxic, and low pH circumstances. Since effector T cells depend on the glycolysis for their survival and functions, the metabolically harsh TME established by cancer cells is unfavorable, resulting in the impairment of effective antitumor immune responses. By contrast, immunosuppressive cells such as regulatory T (Treg) cells can infiltrate, proliferate, survive, and exert immunosuppressive functions in the metabolically harsh TME, indicating the different metabolic dependance between effector T cells and Treg cells. Indeed, some metabolites that are harmful for effector T cells can be utilized by Treg cells; lactic acid, a harmful metabolite for effector T cells, is available for Treg cell proliferation and functions. Deficiency of amino acids such as tryptophan and glutamine in the TME impairs effector T cell activation but increases Treg cell populations. Furthermore, hypoxia upregulates fatty acid oxidation via hypoxia-inducible factor 1α (HIF-1α) and promotes Treg cell migration. Adenosine is induced by the ectonucleotidases CD39 and CD73, which are strongly induced by HIF-1α, and reportedly accelerates Treg cell development by upregulating Foxp3 expression in T cells via A2AR-mediated signals. Therefore, this review focuses on the current views of the unique metabolism of Treg cells dictated by cancer cells. In addition, potential cancer combination therapies with immunotherapy and metabolic molecularly targeted reagents that modulate Treg cells in the TME are discussed to develop "immune metabolism-based precision medicine".

Reprogramming of lipid metabolism in the tumor microenvironment: a strategy for tumor immunotherapy

Lipid metabolism in cancer cells has garnered increasing attention in recent decades. Cancer cells thrive in hypoxic conditions, nutrient deficiency, and oxidative stress and cannot be separated from alterations in lipid metabolism. Therefore, cancer cells exhibit increased lipid metabolism, lipid uptake, lipogenesis and storage to adapt to a progressively challenging environment, which contribute to their rapid growth. Lipids aid cancer cell activation. Cancer cells absorb lipids with the help of transporter and translocase proteins to obtain energy. Abnormal levels of a series of lipid synthases contribute to the over-accumulation of lipids in the tumor microenvironment (TME). Lipid reprogramming plays an essential role in the TME. Lipids are closely linked to several immune cells and their phenotypic transformation. The reprogramming of tumor lipid metabolism further promotes immunosuppression, which leads to immune escape. This event significantly affects the progression, treatment, recurrence, and metastasis of cancer. Therefore, the present review describes alterations in the lipid metabolism of immune cells in the TME and examines the connection between lipid metabolism and immunotherapy.

The implications of FASN in immune cell biology and related diseases

Fatty acid metabolism, particularly fatty acid synthesis, is a very important cellular physiological process in which nutrients are used for energy storage and biofilm synthesis. As a key enzyme in the fatty acid metabolism, fatty acid synthase (FASN) is receiving increasing attention. Although previous studies on FASN have mainly focused on various malignancies, many studies have recently reported that FASN regulates the survival, differentiation, and function of various immune cells, and subsequently participates in the occurrence and development of immune-related diseases. However, few studies to date systematically summarized the function and molecular mechanisms of FASN in immune cell biology and related diseases. In this review, we discuss the regulatory effect of FASN on immune cells, and the progress in research on the implications of FASN in immune-related diseases. Understanding the function of FASN in immune cell biology and related diseases can offer insights into novel treatment strategies for clinical diseases.