Metabolic support of tumour-infiltrating regulatory T cells by lactic acid

Bioresponsive nanoreactor initiates cascade reactions for tumor vascular normalization and lactate depletion to augment immunotherapy

Immune checkpoint blockade (ICB) therapy has revolutionized cancer treatment. However, abnormal tumor vasculature and excess lactate contribute to tumor immunosuppression and confer resistance to ICB therapy, seriously limiting its clinical application. Here, we have developed a bioresponsive nanoreactor, ALMn, which consists of hollow manganese dioxide nanoparticles with encapsulation of lactate oxidase and L-Arginine, to overcome immunosuppression and sensitize ICB therapy. In the tumor microenvironment, lactate oxidase catalyzes lactate to produce hydrogen peroxide, which subsequently oxidizes L-Arginine to generate nitric oxide for vascular normalization. Through cascade reactions, ALMn effectively depletes excess lactate and normalize tumor vasculature, reshaping the immunosuppressive phenotype to an immune-activated one. Transcriptomics and immunological analyses prove that ALMn facilitates the infiltration and activation of effector cells, further potentiating antitumor immunity. Consequently, ALMn sensitizes anti-PD-L1 therapy, significantly suppressing tumor growth with an 83.7 % suppression, and prolonging the survival of mice, with the median survival time increasing from 29.5 days to 54.5 days. Our study demonstrates that ALMn effectively alleviates tumor immunosuppression and synergizes with anti-PD-L1, which shows promise in boosting ICB therapy.

Self-healable and pH-responsive spermidine/ferrous ion complexed hydrogel Co-loaded with CA inhibitor and glucose oxidase for combined cancer immunotherapy through triple ferroptosis mechanism

Tumor microenvironment governs various therapeutic tolerability of cancer such as ferroptosis and immunotherapy through rewiring tumor metabolic reprogramming like Warburg metabolism. Highly expressed carbonic anhydrases (CA) in tumor that maintaining the delicate metabolic homeostasis is thus the most potential target to be modulated to resolve the therapeutic tolerability. Hence, in this article, a self-healable and pH-responsive spermidine/ferrous ion hydrogel loaded with CA inhibitor (acetazolamide, ACZ) and glucose oxidase (ACZ/GOx@SPM-HA Gel) was fabricated through the Schiff-base reaction between spermidine-dextran and oxidized hyaluronic acid, along with ferrous coordination. Investigation on cancer cell lines (MOC-1) demonstrated ACZ/GOx@SPM-HA Gel may induce cellular oxidative stress and mitochondrial dysfunction through disrupting the cellular homeostasis. Moreover, with the facilitation of autophagy induced by spermidine, ACZ/GOx@SPM-HA Gel may trigger a positive feedback loop to maximally amplify cellular ferroptosis and promote DAMPs release. The anti-tumor evaluation on xenograft mice models furtherly proved the local injection of such hydrogel formulation could efficiently inhibit the tumor growth and distinctively promote the immunogenicity of tumor bed to provide a more favorable environment for immunotherapy. Overall, ACZ/GOx@SPM-HA Gel, with such feasible physiochemical properties and great biocompatibility, holds great potential in treating solid tumors with acidosis-mediated immunotherapy tolerance.

Priming of cancer-immunity cycle by alleviating hypoxia-induced ferroptosis resistance and immunosuppression

Stimulating a robust cancer-immunity cycle (CIC) holds promising potential for eliciting potent and enduring immune responses for cancer immunotherapy. However, designing a therapeutic nanomaterial capable of both enhancing tumor immunogenicity and mitigating immunosuppression is challenging and often associated with complicated design paradigms and immune-related adverse effects. Herein, a multienzyme-mimetic alloy nanosheet incorporating palladium (Pd) and iron (Fe) is developed, which can prime effective CIC by overcoming ferroptosis resistance for enhancing tumor immunogenicity and reprograming the tumor microenvironment for enhanced second near-infrared (NIR-II) photoimmunotherapy. The nanosheets accumulate in tumors when administered intravenously and counteract hypoxia through catalase-like oxygen production and subsequent reduction of hypoxia-inducible factor-1α, M2-like macrophages, regulatory T-cell, and programmed death-ligand 1 (PD-L1) expression. The surface plasmon resonance of the nanosheets enables NIR-II phototherapy and photoacoustic imaging, coupling with its ferroptosis and tumor microenvironment reprogram properties to synergize with anti-PD-L1 checkpoint blockade therapy to achieve satisfactory antitumor outcome. This study offers a strategy for localized tumor treatment and boosting the CIC through a straightforward and inexpensive nanomaterial design.

Invasion and metastasis in cancer: molecular insights and therapeutic targets

The progression of malignant tumors leads to the development of secondary tumors in various organs, including bones, the brain, liver, and lungs. This metastatic process severely impacts the prognosis of patients, significantly affecting their quality of life and survival rates. Research efforts have consistently focused on the intricate mechanisms underlying this process and the corresponding clinical management strategies. Consequently, a comprehensive understanding of the biological foundations of tumor metastasis, identification of pivotal signaling pathways, and systematic evaluation of existing and emerging therapeutic strategies are paramount to enhancing the overall diagnostic and treatment capabilities for metastatic tumors. However, current research is primarily focused on metastasis within specific cancer types, leaving significant gaps in our understanding of the complex metastatic cascade, organ-specific tropism mechanisms, and the development of targeted treatments. In this study, we examine the sequential processes of tumor metastasis, elucidate the underlying mechanisms driving organ-tropic metastasis, and systematically analyze therapeutic strategies for metastatic tumors, including those tailored to specific organ involvement. Subsequently, we synthesize the most recent advances in emerging therapeutic technologies for tumor metastasis and analyze the challenges and opportunities encountered in clinical research pertaining to bone metastasis. Our objective is to offer insights that can inform future research and clinical practice in this crucial field.

Dysfunctional CD11c-CD21- extrafollicular memory B cells are enriched in the periphery and tumors of patients with cancer

Many patients with recurrent and metastatic cancer fail to produce a durable response to immunotherapy, highlighting the need for additional therapeutic targets to improve the immune landscape in tumors. Recent studies have highlighted the importance of B cells in the antitumor response, with memory B cells (MBCs) being prognostic in a variety of solid tumors. MBCs are a heterogenous B cell subset and can be generated through both germinal center reactions and extrafollicular (EF) responses. EF-derived MBCs have been recently linked to poor prognosis and treatment resistance in solid tumors and thus may represent candidate biomarkers or immunotherapy targets. EF-derived MBCs, termed "double-negative" (DN) MBCs may be further classified on the basis of surface expression of CD11c and CD21 into DN1, DN2, and DN3 MBCs. CD11c-CD21+ DN1 MBCs and CD11c+CD21- DN2 MBCs have been well studied across inflammatory diseases; however, the biology and clinical relevance of CD11c-CD21- DN3 MBCs remain unknown. Here, we report an accumulation of DN3 MBCs in the blood and tumors of patients with head and neck squamous cell carcinoma (HNSCC) and an increase in DN3 MBCs in locally advanced HNSCC tumors. Circulating and intratumoral DN3 MBCs were hyporesponsive to antigen stimulation, had low antibody production, and failed to differentiate into antibody-secreting cells. Moreover, DN3 MBCs accumulated selectively outside of tertiary lymphoid structures. Last, circulating DN3 MBCs correlated with poor therapeutic response, advanced disease, and worse outcomes in patients with HNSCC and melanoma, supporting further assessment of EF-derived MBCs as potential biomarkers and therapeutic targets.

Transcytosis-Triggering Nanoparticles for Overcoming Stromal Barriers and Reversing Immunosuppression in Pancreatic Cancer Combinatorial Therapy

In pancreatic ductal adenocarcinoma (PDAC), stromal cells and matrix proteins form a dense physical barrier that, while preventing the outward spread of tumor cells, also limits the penetration of drugs and CD8+ T cells inward. Additionally, the overactivated TGF-β/SMAD signaling pathway further promotes matrix proliferation and immune suppression. Therefore, crossing the stromal barrier while preserving the integrity of the stroma, releasing drugs intratumorally, remodeling the stroma, and activating the immune system is a promising drug delivery strategy. In this work, a type of enamine N-oxides modified nanoparticle was prepared, with stearic acid-modified gemcitabine prodrug (GemC18) and pSMAD2/3 inhibitor galunisertib encapsulated. The peripheral enamine N-oxides can trigger transcytosis and then respond to hypoxia and acidic microenvironments, turning the surface charge of the nanoparticles to a positive charge and enhancing penetration. The released galunisertib inhibits the TGF-β/SMAD signaling pathway, reshapes the matrix, activates antitumor immunity, and combines with gemcitabine (Gem) to kill tumor cells.

Energy metabolism in health and diseases

Energy metabolism is indispensable for sustaining physiological functions in living organisms and assumes a pivotal role across physiological and pathological conditions. This review provides an extensive overview of advancements in energy metabolism research, elucidating critical pathways such as glycolysis, oxidative phosphorylation, fatty acid metabolism, and amino acid metabolism, along with their intricate regulatory mechanisms. The homeostatic balance of these processes is crucial; however, in pathological states such as neurodegenerative diseases, autoimmune disorders, and cancer, extensive metabolic reprogramming occurs, resulting in impaired glucose metabolism and mitochondrial dysfunction, which accelerate disease progression. Recent investigations into key regulatory pathways, including mechanistic target of rapamycin, sirtuins, and adenosine monophosphate-activated protein kinase, have considerably deepened our understanding of metabolic dysregulation and opened new avenues for therapeutic innovation. Emerging technologies, such as fluorescent probes, nano-biomaterials, and metabolomic analyses, promise substantial improvements in diagnostic precision. This review critically examines recent advancements and ongoing challenges in metabolism research, emphasizing its potential for precision diagnostics and personalized therapeutic interventions. Future studies should prioritize unraveling the regulatory mechanisms of energy metabolism and the dynamics of intercellular energy interactions. Integrating cutting-edge gene-editing technologies and multi-omics approaches, the development of multi-target pharmaceuticals in synergy with existing therapies such as immunotherapy and dietary interventions could enhance therapeutic efficacy. Personalized metabolic analysis is indispensable for crafting tailored treatment protocols, ultimately providing more accurate medical solutions for patients. This review aims to deepen the understanding and improve the application of energy metabolism to drive innovative diagnostic and therapeutic strategies.

Regulatory T cells in the tumor microenvironment display a unique chromatin accessibility profile

Regulatory T cells (Tregs) are a suppressive CD4+ T cell population that limit the antitumor immune response. In this study, we analyzed the chromatin accessibility of Tregs in the murine tumor microenvironment (TME) to identify tumor-specific accessible peaks and if these are altered over time in the tumor microenvironment, with or without anti-PD-1 immunotherapy. We found that despite little change in chromatin accessibility of Tregs in the tumor over time, Tregs have a distinct chromatin accessibility signature in the TME compared with Tregs in the periphery. This distinct tumor Treg chromatin accessibility profile highlights reduced accessibility at loci important for an CD4+ conventional T cell (CD4+ Foxp3-) effector phenotype. Analysis of chromatin accessibility in Tregs from B16 and MC38 tumor models indicated that Tregs from skin-resident tumors are most similar to naïve skin resident Tregs but still bear key differences attributable to the TME. We also found that Tregs do not alter their transcriptome or chromatin accessibility following immunotherapy. We conclude that although chromatin accessibility in Tregs is somewhat similar to their tissue residency, the TME may drive a unique chromatin accessibility profile. Treg chromatin accessibility in the tumor appears remarkably stable and unaltered by tumor type, over time, or following immunotherapy.

Tumor-derived lactic acid promotes acetylation of histone H3K27 and differentiation of IL-10-producing regulatory B cells through direct and indirect signaling pathways

Tumor cells are known to enhance glycolysis, even under normoxic conditions, via the Warburg effect, producing excess lactic acid in the tumor microenvironment. Lactic acid enhances the IL-23/IL-17 pathway and induces chronic inflammation. The acidic microenvironment formed by lactic acid suppresses immune cell proliferation and activation. In the present study, we clarified that lactic acid had two novel activities for immune cells. First, lactic acid specifically enhanced acetylation at lysine 27 of histone H3 (H3K27ac) in splenic B cells and monocytes/macrophages, and this epigenetically up-regulates the expression of genes. Acetylation and methylation of other residues of histone H3 were rarely induced. Second, lactic acid induced a particularly-marked enhancement of Il10 gene expression in B cells, leading to an increase in IL-10-producing regulatory B (Breg) cells. Furthermore, two pathways should be involved in both the enhancement of H3K27ac and the induction of Breg cells by lactic acid: a direct pathway that enhances the CD40 signal in B cells, and an indirect pathway that affects B cells by activating the exchange protein directly activated by cAMP (EPAC) 1/2 in non-B cells. In tumor-bearing mice, the levels of H3K27ac of tumor-infiltrating B cells were significantly higher than splenic B cells and were suppressed by intraperitoneal injection of the EPAC1/2 inhibitor. In conclusion, tumor-derived lactic acid increases H3K27ac and IL-10-producing Breg cells, causing the suppression of anti-tumor immunity.

Lactate and lactylation in cancer

Accumulated evidence has implicated the diverse and substantial influence of lactate on cellular differentiation and fate regulation in physiological and pathological settings, particularly in intricate conditions such as cancer. Specifically, lactate has been demonstrated to be pivotal in molding the tumor microenvironment (TME) through its effects on different cell populations. Within tumor cells, lactate impacts cell signaling pathways, augments the lactate shuttle process, boosts resistance to oxidative stress, and contributes to lactylation. In various cellular populations, the interplay between lactate and immune cells governs processes such as cell differentiation, immune response, immune surveillance, and treatment effectiveness. Furthermore, communication between lactate and stromal/endothelial cells supports basal membrane (BM) remodeling, epithelial-mesenchymal transitions (EMT), metabolic reprogramming, angiogenesis, and drug resistance. Focusing on lactate production and transport, specifically through lactate dehydrogenase (LDH) and monocarboxylate transporters (MCT), has shown promise in the treatment of cancer. Inhibitors targeting LDH and MCT act as both tumor suppressors and enhancers of immunotherapy, leading to a synergistic therapeutic effect when combined with immunotherapy. The review underscores the importance of lactate in tumor progression and provides valuable perspectives on potential therapeutic approaches that target the vulnerability of lactate metabolism, highlighting the Heel of Achilles for cancer treatment.

Tumor secretome shapes the immune landscape during cancer progression

The focus of cancer immunotherapy has traditionally been on immune cells and tumor cells themselves, often overlooking the tumor secretome. This review provides a comprehensive overview of the intricate relationship between tumor cells and the immune response in cancer progression. It highlights the pivotal role of the tumor secretome - a diverse set of molecules secreted by tumor cells - in significantly influencing immune modulation, promoting immunosuppression, and facilitating tumor survival. In addition to elucidating these complex interactions, this review discusses current clinical trials targeting the tumor secretome and highlights their potential to advance personalized medicine strategies. These trials aim to overcome the challenges of the tumor microenvironment by designing therapies tailored to the secretome profiles of individual cancer patients. In addition, advances in proteomic techniques are highlighted as essential tools for unraveling the complexity of the tumor secretome, paving the way for improved cancer treatment outcomes.

Biomimetic calcium-chelation nanoparticles reprogram tumor metabolism to enhance antitumor immunity

Metabolic reprogramming within the tumor microenvironment poses a significant obstacle to the therapeutic efficacy of antitumor immunity. Here, inspired by the diverse programme of cholesterol metabolism between tumor and immune cells, a biocompatible carboxy-modified cyclodextrin carrier equipped with a biomimetic surface was developed to encapsulate FX11 and Avasimibe (RM-CDC@FX11&Ava) for synergistic antitumor metabolic therapy and immunotherapy. Through the manipulation of calcium levels using poly-carboxylic compounds to initiate cholesterol biosynthesis, RM-CDC@FX11&Ava dynamically regulates glycolysis and blocks cholesterol esterification to navigate metabolic reprogramming. The resultant cholesterol augmentation triggered by RM-CDC@FX11&Ava could not only specifically induce 34.3 % tumor cell apoptosis but also promote 57.8 % dendritic cell maturation for antigen presentation and improve the effector function of T cells. Furthermore, the tumor immunosuppressive microenvironment was also reprogrammed by impairing Treg cells through the blockade of lactic acid. As a result, RM-CDC@FX11&Ava showed superior antitumor efficacy in mastadenoma and melanoma models.

Immunometabolism of Liver Xenotransplantation and Prospective Solutions

End-stage liver diseases, such as hepatocellular carcinoma or acute liver failure, critically necessitate liver transplantation. However, the shortage of available organ donors fails to meet the rapidly growing transplantation demand. Due to the high similarity of liver tissue structure and metabolism between miniature pigs and humans, xenotransplantation of pig livers is considered as a potentially viable solution to organ scarcity. In the 2024, teams from China first time have successfully transplanted a genetically modified Bama miniature pig liver into a clinically brain-dead man lasting for 10 days. This milestone in human xenotransplantation research not only confirms the feasibility of clinical application of xenotransplantation, but also underscores the daunting and protracted nature of this pathway. Despite advanced gene-editing technologies theoretically circumventing the occurrence of most transplant rejection reactions, patients still face challenges such as chronic immune rejection, coagulation disorders, and thrombotic microangiopathy after receiving xenografts. Moreover, prolonged use of immunosuppressive drugs may induce irreversible immune dysfunction, leading to opportunistic infections and metabolic disorders. This article compares the similarities and differences in livers between humans and pigs, summarizes the immunometabolism of xenotransplantation based on current findings, and provides research perspectives on pre-transplantation and post-transplantation strategies for prolonging the survival time of xenografts.

Copper-doped layered double hydroxides co-deliver proteins/drugs for cascaded chemodynamic/immunotherapy via dual regulation of tumor metabolism

We report here a Cu2+-doped layered double hydroxide (LDH) nanoplatform to load both monocarboxylate transporter inhibitor diclofenac (DC) and lactate oxidase (LOX) for dual modulation of tumor lactate and redox metabolisms to activate immunotherapy through enhanced Cu-mediated chemodynamic therapy (CDT) of tumors. The formed LDH-DC-LOX nanoparticles with a diameter of 55 nm are stable, can be effectively taken up by cancer cells to regulate lactate through both LOX-mediated catalytic conversion and DC-enabled inhibition of extracellular efflux of lactate, and can exert redox metabolism through CDT via Cu2+-mediated glutathione (GSH) depletion and Fenton-like reaction with hydrogen peroxide (H2O2) that can be further accumulated via LOX-mediated catalysis. The major advantage of the developed LDH-DC-LOX nanoparticles lies in the therapeutic synergy and cascade that can be achieved through the loaded DC and LOX for enhanced tumor lactate metabolism regulation, for enhanced Cu-mediated CDT and redox metabolism regulation, and for activation of immunotherapy that can further enhances the Cu2+-mediated CDT effect. The developed LDH nanoplatform demonstrated here for effective murine breast tumor treatment provides a new paradigm for dual regulation of lactate and redox metabolisms that may enable synergistic and cascaded combination therapy of different cancer types. STATEMENT OF SIGNIFICANCE: Targeting the tumor microenvironment (TME) to alter tumor metabolic pathways represents a promising strategy for next-generation cancer therapy. Herein, a copper-doped layered double hydroxide (LDH) nanoplatform is developed to co-deliver both diclofenac (DC) and lactate oxidase (LOX) to tumor cells for efficient dual regulation of tumor lactate and redox metabolisms, resulting in synergistic and cascaded chemodynamic therapy/immunotherapy of breast tumors. The developed LDH-DC-LOX nanoparticles can release Cu2+ and DC under an acidic TME, and can act in synergy to reduce TME lactate and generate H2O2, thus modulating redox metabolism and activating anticancer immunotherapy. The secreted cytokine IFN-γ after activation of antitumor immune responses can further mediate enhanced chemodynamic therapy effect through downregulation of cystine/glutamate transporter SLC7A11 to suppress GSH synthesis.

The lactate receptor HCAR1 drives the recruitment of immunosuppressive PMN-MDSCs in colorectal cancer

Most patients with colorectal cancer do not achieve durable clinical benefits from immunotherapy, underscoring the existence of alternative immunosuppressive mechanisms. Here we found that activation of the lactate receptor HCAR1 signaling pathway induced the expression of chemokines CCL2 and CCL7 in colorectal tumor cells, leading to the recruitment of immunosuppressive CCR2+ polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) to the tumor microenvironment. Ablation of Hcar1 in mice with colorectal tumors significantly decreased the abundance of tumor-infiltrating CCR2+ PMN-MDSCs, enhanced the activation of CD8+ T cells and, consequently, reduced tumor burden. We detected immunosuppressive CCR2+ PMN-MDSCs in tumor specimens from individuals with colorectal and other cancers. The US Food and Drug Administration-approved drug reserpine suppressed lactate-mediated HCAR1 activation, impaired the recruitment of CCR2+ PMN-MDSCs, boosted CD8+ T cell-dependent antitumor immunity and sensitized immunotherapy-resistant tumors to programmed cell death protein 1 antibody therapy in mice with colorectal tumors. Altogether, we described HCAR1-driven recruitment of CCR2+ PMN-MDSCs as a mechanism of immunosuppression.

Metabolic Singularities in Microsatellite-Stable Colorectal Cancer: Identifying Key Players in Immunosuppression to Improve the Immunotherapy Response

Although immune checkpoint inhibitor (ICI) therapy is currently the standard of care in microsatellite-unstable (MSI) metastatic colorectal cancer (CRC), ICI therapy, alone or in combination with other therapies, is not a treatment approach in microsatellite-stable (MSS) CRC, which is present in 95% of patients. In this review, we focus on metabolic singularities-at the transcriptomic (either bulk or single cell), proteomic, and post-translational modification levels-that induce immunosuppression in cancer and specifically in MSS CRC. First, we evaluate the current efficacy of ICIs in limited and metastatic disease in MSS CRC. Second, we discuss the latest findings on the potential biomarkers for evaluating ICI efficacy in MSS CRC using strict REMARK criteria. Third, we review the current evidence on metabolic patterns in CRC tumors and immune cell metabolism to advance our understanding of metabolic crosstalk and to pave the way for the development of combination strategies to enhance ICI efficacy.

Tanshinone I reprograms glycolysis metabolism to regulate histone H3 lysine 18 lactylation (H3K18la) and inhibits cancer cell growth in ovarian cancer

Salvia miltiorrhiza, the anticancer properties of these components are multifaceted, encompassing the inhibition of tumor growth, prevention of the metastatic spread of cancer cells, enhancement of the sensitivity of cancer cells to chemotherapy and radiation therapy, and the suppression of angiogenesis, which is crucial for tumor growth and survival. In the context of our recent study, we have discovered that tanshinone I, one of the active components of Salvia miltiorrhiza, possesses the ability to inhibit the proliferation of ovarian cancer cells, both in laboratory settings and within living organisms. To further understand the molecular mechanisms behind this effect, we conducted a comprehensive transcriptomic analysis. Our findings indicated that tanshinone I exerts its inhibitory action by downregulating the expression of genes associated with glycolysis. Specifically, tanshinone I decreased the expression of glycolysis-related genes such as HK2 (hexokinase 2), PFK (phosphofructokinase), ENO2 (enolase 2), and LDHA (lactate dehydrogenase A). Inhibiting lactate production by tanshinone I application reduced the level of histone H3 lysine 18 lactylation (H3K18la), which reduced the expression of tumor-associated genes, such as TTK, PDGFRβ, YTHDF2 and RUBCNL. In addition, tanshinone I alleviated the immunosuppressive tumor microenvironment. In summary, tanshinone I blocks glycolysis to regulate histone H3 lysine 18 lactylation (H3K18la), which inhibits ovarian cancer cell growth, revealing the anticancer mechanism of tanshinone I.

Exploring glycolytic enzymes in disease: potential biomarkers and therapeutic targets in neurodegeneration, cancer and parasitic infections

Glycolysis, present in most organisms, is evolutionarily one of the oldest metabolic pathways. It has great relevance at a physiological level because it is responsible for generating ATP in the cell through the conversion of glucose into pyruvate and reducing nicotinamide adenine dinucleotide (NADH) (that may be fed into the electron chain in the mitochondria to produce additional ATP by oxidative phosphorylation), as well as for producing intermediates that can serve as substrates for other metabolic processes. Glycolysis takes place through 10 consecutive chemical reactions, each of which is catalysed by a specific enzyme. Although energy transduction by glucose metabolism is the main function of this pathway, involvement in virulence, growth, pathogen-host interactions, immunomodulation and adaptation to environmental conditions are other functions attributed to this metabolic pathway. In humans, where glycolysis occurs mainly in the cytosol, the mislocalization of some glycolytic enzymes in various other subcellular locations, as well as alterations in their expression and regulation, has been associated with the development and progression of various diseases. In this review, we describe the role of glycolytic enzymes in the pathogenesis of diseases of clinical interest. In addition, the potential role of these enzymes as targets for drug development and their potential for use as diagnostic and prognostic markers of some pathologies are also discussed.

Lactylation: The metabolic accomplice shaping cancer's response to radiotherapy and immunotherapy

Protein lactylation, an emerging post-translational modification, is providing new insights into tumor biology and challenging our current understanding of cancer mechanisms. Our review illuminates the intricate roles of lactylation in carcinogenesis, tumor progression, and therapeutic responses, positioning it as a critical linchpin connecting metabolic reprogramming, epigenetic modulation, and treatment outcomes. We provide an in-depth analysis of lactylation's molecular mechanisms and its far-reaching impact on cell cycle regulation, immune evasion strategies, and therapeutic resistance within the complex tumor microenvironment. Notably, this review dissects the paradoxical nature of lactylation in cancer immunotherapy and radiotherapy. While heightened lactylation can foster immune suppression and radioresistance, strategically targeting lactylation cascades opens innovative avenues for amplifying the efficacy of current treatment paradigms. We critically evaluate lactylation's potential as a robust diagnostic and prognostic biomarker and explore frontier therapeutic approaches targeting lactylation. The synergistic integration of multi-omics data and artificial intelligence in lactylation research is catalyzing significant strides towards personalized cancer management. This review not only consolidates current knowledge but also charts a course for future investigations. Key research imperatives include deciphering tumor-specific lactylation signatures, optimizing synergistic strategies combining lactylation modulation with immune checkpoint inhibitors and radiotherapy, and comprehensively assessing the long-term physiological implications of lactylation intervention. As our understanding of lactylation's pivotal role in tumor biology continues to evolve, this burgeoning field promises to usher in transformative advancements in cancer diagnosis, treatment modalitie.

Sex-related changes in lactate dehydrogenase A expression differently impact the immune response in melanoma

Melanoma is more aggressive in male patients than female ones and this is associated with sexual dimorphism in immune responses. Taking into consideration the impact tumour metabolic alterations in affecting the immune landscape, we aimed to investigate the effect of the sex-dependent metabolic profile of melanoma in re-shaping immune composition. Melanoma is characterised by Warburg metabolism, and secreted lactate has emerged as a key driver in the establishment of an immunosuppressive environment. Here, we identified lactate dehydrogenase A (LDH-A) as a crucial player in modulating sex-related differences in melanoma immune responses, both in vitro and in patient-derived specimens. LDH-A is associated with higher lactate secretion in male melanoma cells, which leads to a significant enrichment in pro-tumoural regulatory T cells (Treg) with a concurrent decrease in the number and activity of anti-tumour CD8+ T cells. Remarkably, pharmacological and genetic impairment of LDH-A in male melanoma cells normalises Treg and CD8+ infiltration. In keeping with this, in vivo pharmacological targeting of LDH-A in melanoma-bearing male mice impairs tumour growth and lung colonisation, with a concomitant modulation of Treg and CD8+ T cells infiltration. Taken together, our findings highlight the sex-related differences promoted by LDH-A in immune reshaping in melanoma, and suggest that therapeutic targeting of LDH-A could be leveraged as an effective strategy to abolish the sex-gap in melanoma progression.

Tumor-induced metabolic immunosuppression: Mechanisms and therapeutic targets

Metabolic reprogramming in both immune and cancer cells plays a crucial role in the antitumor immune response. Recent studies indicate that cancer metabolism not only sustains carcinogenesis and survival via altered signaling but also modulates immune cell function. Metabolic crosstalk within the tumor microenvironment results in nutrient competition and acidosis, thereby hindering immune cell functionality. Interestingly, immune cells also undergo metabolic reprogramming that enables their proliferation, differentiation, and effector functions. This review highlights the regulation of antitumor immune responses through metabolic reprogramming in cancer and immune cells and explores therapeutic strategies that target these metabolic pathways in cancer immunotherapy, including using chimeric antigen receptor (CAR)-T cells. We discuss innovative combinations of immunotherapy, cellular therapies, and metabolic interventions that could optimize the efficacy of existing treatment protocols.

A thermoplastic chip for 2D and 3D correlative assays combining screening and high-resolution imaging of immune cell responses

We present an easy-to-use, disposable, thermoplastic microwell chip designed to support screening and high-resolution imaging of single-cell behavior in two- and three-dimensional (2D and 3D) cell cultures. We show that the chip has excellent optical properties and provide simple protocols for efficient long-term cell culture of suspension and adherent cells, the latter grown either as monolayers or as hundreds of single, uniformly sized spheroids. We then demonstrate the applicability of the system for single-cell analysis by correlating the dynamic cytotoxic response of single immune cells grown under different metabolic conditions to their intracellular cytolytic load at the end of the assay. Additionally, we illustrate highly multiplex cytotoxicity screening of tumor spheroids in the chip, comparing the effect of environment cues characteristic of the tumor microenvironment on natural killer (NK)-cell-induced killing. Following the functional screening, we perform high-resolution 3D immunofluorescent imaging of infiltrating NK cells within the spheroid volumes.

Non-histone lactylation: unveiling its functional significance

Lactylation, a newly discovered protein posttranslational modification (PTM) in 2019, primarily occurs on lysine residues. Lactylation of histones was initially identified, and subsequent studies have increasingly demonstrated its widespread presence on non-histone proteins. Recently, high-throughput proteomics studies have identified a large number of lactylated proteins and sites, revealing their global regulatory role in disease development. Notably, this modification is catalyzed by lactyltransferase and reversed by delactylase, with numerous new enzymes, such as AARS1/2, reported to be involved. Specifically, these studies have revealed how lactylation exerts its influence through alterations in protein spatial conformation, molecular interactions, enzyme activity and subcellular localization. Indeed, lactylation is implicated in various physiological and pathological processes, including tumor development, cardiovascular and cerebrovascular diseases, immune cell activation and psychiatric disorders. This review provides the latest advancements in research on the regulatory roles of non-histone protein lactylation, highlighting its crucial scientific importance for future studies.

Emerging insights into the impact of systemic metabolic changes on tumor-immune interactions

Tumors are inherently embedded in systemic physiology, which contributes metabolites, signaling molecules, and immune cells to the tumor microenvironment. As a result, any systemic change to host metabolism can impact tumor progression and response to therapy. In this review, we explore how factors that affect metabolic health, such as diet, obesity, and exercise, influence the interplay between cancer and immune cells that reside within tumors. We also examine how metabolic diseases influence cancer progression, metastasis, and treatment. Finally, we consider how metabolic interventions can be deployed to improve immunotherapy. The overall goal is to highlight how metabolic heterogeneity in the human population shapes the immune response to cancer.

A risk signature constructed by Tregs-related genes predict the clinical outcomes and immune therapeutic response in kidney cancer

Regulatory T cells (Tregs) have been found to be related to immune therapeutic resistance in kidney cancer. However, the potential Tregs-related genes still need to be explored. Our study found that patients with high Tregs activity show poor prognosis. Through co-expression and differential expression analysis, we screened several Tregs-related genes (KTRGs) in kidney renal clear cell carcinoma. We further conducted the univariate Cox regression analysis and determined the prognosis-related KTRGs. Through the machine learning algorithm-Boruta, the potentially important KTRGs were screened further and submitted to construct a risk model. The risk model could predict the prognosis of RCC patients well, high risk patients show a poorer outcomes than low risk patients. Multivariate Cox regression analysis reveals that risk score is an independent prognostic factor. Then, the nomogram model based on KTRG risk score and other clinical variables was further established, which shows a high predicted accuracy and clinical benefit based on model validation methods. In addition, we found EMT, JAK/STAT3, and immune-related pathways highly enriched in high risk groups, while metabolism-related pathways show a low enrichment. Through analyzing two other external immune therapeutic datasets, we found that the risk score could predict the patient's immune therapeutic response. High-risk groups represent a worse therapeutic response than low-risk groups. In summary, we identified several Tregs-related genes and constructed a risk model to predict prognosis and immune therapeutic response. We hope these organized data can provide a theoretical basis for exploring potential Tregs' targets to synergize the immune therapy for RCC patients.

Nanomaterial-enabled metabolic reprogramming strategies for boosting antitumor immunity

Immunotherapy has become a crucial strategy in cancer treatment, but its effectiveness is often constrained. Most cancer immunotherapies focus on stimulating T-cell-mediated immunity by driving the cancer-immunity cycle, which includes tumor antigen release, antigen presentation, T cell activation, infiltration, and tumor cell killing. However, metabolism reprogramming in the tumor microenvironment (TME) supports the viability of cancer cells and inhibits the function of immune cells within this cycle, presenting clinical challenges. The distinct metabolic needs of tumor cells and immune cells require precise and selective metabolic interventions to maximize therapeutic outcomes while minimizing adverse effects. Recent advances in nanotherapeutics offer a promising approach to target tumor metabolism reprogramming and enhance the cancer-immunity cycle through tailored metabolic modulation. In this review, we explore cutting-edge nanomaterial strategies for modulating tumor metabolism to improve therapeutic outcomes. We review the design principles of nanoplatforms for immunometabolic modulation, key metabolic pathways and their regulation, recent advances in targeting these pathways for the cancer-immunity cycle enhancement, and future prospects for next-generation metabolic nanomodulators in cancer immunotherapy. We expect that emerging immunometabolic modulatory nanotechnology will establish a new frontier in cancer immunotherapy in the near future.

Targeting SLC4A4: A Novel Approach in Colorectal Cancer Drug Repurposing

BACKGROUND

Colorectal cancer (CRC) is a complex and increasingly prevalent malignancy with significant challenges in its treatment and prognosis. This study aims to explore the role of the SLC4A4 transporter as a biomarker in CRC progression and its potential as a therapeutic target, particularly in relation to tumor acidity and immune response.

METHODS

The study utilized computational approaches, including receptor-based virtual screening and high-throughput docking, to identify potential SLC4A4 inhibitors. A model of the human SLC4A4 structure was generated based on CryoEM data (PDB ID 6CAA), and drug candidates from the DrugBank database were evaluated using two computational tools (DrugRep and CB-DOCK2).

RESULTS

The study identified the compound (5R)-N-[(1r)-3-(4-hydroxyphenyl)butanoyl]-2-decanamide (DB07991) as the best ligand, demonstrating favorable binding affinity and stability. Molecular dynamics simulations revealed strong protein-ligand interactions with consistent RMSD (~0.25 nm), RMSF (~0.5 nm), compact Rg (4.0-3.9 nm), and stable SASA profiles, indicating that the SLC4A4 structure remains stable upon ligand binding.

CONCLUSIONS

The findings suggest that DB07991 is a promising drug candidate for further investigation as a therapeutic agent against CRC, particularly for targeting SLC4A4. This study highlights the potential of computational drug repositioning in identifying effective treatments for colorectal cancer.

CD4+FOXP3Exon2+ regulatory T cell frequency predicts breast cancer prognosis and survival

CD4+FOXP3+ regulatory T cells (Tregs) suppress immune responses to tumors, and their accumulation in the tumor microenvironment (TME) correlates with poor clinical outcome in several cancers, including breast cancer (BC). However, the properties of intratumoral Tregs remain largely unknown. Here, we found that a functionally distinct subpopulation of Tregs, expressing the FOXP3 Exon2 splicing variants, is prominent in patients with hormone receptor-positive BC with poor prognosis. Notably, a comprehensive examination of the TCGA validated FOXP3E2 as an independent prognostic marker in all other BC subtypes. We found that FOXP3E2 expression underlies BCs with defective mismatch repair and a stem-like signature and highlights pathways involved in tumor survival. Last, we found that the TME induces FOXP3E2 through the CXCL12/CXCR4 axis and confirmed the higher immunosuppressive capacity of FOXP3E2+ Tregs derived from patients with BC. Our study suggests that FOXP3E2+ Tregs might be used as an independent biomarker to predict BC prognosis and survival and to develop super-targeted immunotherapies.

Delactylation diminished the growth inhibitory role of CA3 by restoring DUOX2 expression in hepatocellular carcinoma

Lactylation is an emerging pathogenesis of hepatocellular carcinoma (HCC). However, the underlying mechanisms and biological significance remain poorly understood. The Carbonic anhydrase III (CA3) gene, previously defined as a binding protein of SQLE and involved in the NAFLD disease, has now been identified as a novel tumor suppressor in HCC. mRNA expression of CA3 is associated with a favorable prognosis and negatively correlated with serum lactate levels, whereas CA3 protein expression does not correlate with patient prognosis or serum lactate levels, suggested there has lactate-related post-translational modification of CA3 in HCC. Overexpression of CA3 induces cell apoptosis, thereby reducing intracellular reactive oxygen stress (ROS) through the inhibition of DUOX2 expression. The decreased lactylation level of CA3 protein at the K36 residues, induced by SQLE, results in the loss of the anti-cancer effect of CA3. Together, this study has demonstrated that CA3 is a novel tumor suppressor in HCC, and delactylation of CA3 represents a newly identified mechanism by which HCC cells evade growth suppressors.

Mannose metabolism reshapes T cell differentiation to enhance anti-tumor immunity

Cellular metabolic status profoundly influences T cell differentiation, persistence, and anti-tumor efficacy. Our single-cell metabolic analyses of T cells reveal that diminished mannose metabolism is a prominent feature of T cell dysfunction. Conversely, experimental augmentation/restoration of mannose metabolism in adoptively transferred T cells via D-mannose supplementation enhances anti-tumor activity and restricts exhaustion differentiation both in vitro and in vivo. Mechanistically, D-mannose treatment induces intracellular metabolic programming and increases the O-GlcNAc transferase (OGT)-mediated O-GlcNAcylation of β-catenin, which preserves Tcf7 expression and epigenetic stemness, thereby promoting stem-like programs in T cells. Furthermore, in vitro expansion with D-mannose supplementation yields T cell products for adoptive therapy with stemness characteristics, even after extensive long-term expansion, that exhibits enhanced anti-tumor efficacy. These findings reveal cell-intrinsic mannose metabolism as a physiological regulator of CD8+ T cell fate, decoupling proliferation/expansion from differentiation, and underscoring the therapeutic potential of mannose modulation in cancer immunotherapy.

Revisiting of Cancer Immunotherapy: Insight from the Dialogue between Glycolysis and PD-1/PD-L1 Axis in the Tumor Microenvironment

The interplay between metabolic pathways and immune escape has emerged as a captivating research area in oncobiology. Among these, the Warburg effect stands out as a hallmark metabolic reprogramming in cancer, characterized by elevated glucose utilization and excessive lactic acid production through anaerobic glycolysis. Key glycolytic enzymes not only fulfill the bioenergetic demands of cancer cells but also exhibit moonlighting roles, including regulation of epigenetic modifications, protein kinase activity, and immune escape mechanisms, thereby reshaping the tumor microenvironment. Tumor-specific vascular architecture facilitates lactate accumulation, which drives tumor progression by impairing immune cell function and acting as a signaling molecule to recruit immunosuppressive cells and modulate immune checkpoint pathways. The PD-1/PD-L1 co-stimulatory pathway plays a crucial role in negatively modulating the activation, proliferation, and cytokine secretion by T-lymphocytes. This review primarily focuses on elucidating the regulation and mechanisms underlying PD-1/PD-L1 signaling axis during glycolysis in tumor cells as well as surrounding cells. In the era of precision medicine, there is a particular interest in leveraging 18F-FDG PET/CT imaging as a valuable tool to assess PD-L1 expression status for more targeted therapeutic interventions. Additionally, the development of natural compounds capable of modulating metabolism opens new avenues for metabolism-based immunotherapy, though further studies are required to validate their in vivo efficacy.

Lactate-induced protein lactylation in cancer: functions, biomarkers and immunotherapy strategies

Lactate, long viewed as a byproduct of glycolysis and metabolic waste. Initially identified within the context of yogurt fermentation, lactate's role extends beyond culinary applications to its significance in biochemical processes. Contemporary research reveals that lactate functions not merely as the terminal product of glycolysis but also as a nexus for initiating physiological and pathological responses within the body. Lysine lactylation (Kla), a novel post-translational modification (PTM) of proteins, has emerged as a pivotal mechanism by which lactate exerts its regulatory influence. This epigenetic modification has the potential to alter gene expression patterns, thereby impacting physiological and pathological processes. Increasing evidence indicates a correlation between lactylation and adverse prognosis in various malignancies. Consequently, this review article aims to encapsulate the proteins that interact with lactate, elucidate the role of lactylation in tumorigenesis and progression, and explore the potential therapeutic targets afforded by the modulation of lactylation. The objective of this review is to clarify the oncogenic significance of lactylation and to provide a strategic framework for future research directions in this burgeoning field.

Tumor metabolic regulators: key drivers of metabolic reprogramming and the promising targets in cancer therapy

Metabolic reprogramming within the tumor microenvironment (TME) is a hallmark of cancer and a crucial determinant of tumor progression. Research indicates that various metabolic regulators form a metabolic network in the TME and interact with immune cells, coordinating the tumor immune response. Metabolic dysregulation creates an immunosuppressive TME, impairing the antitumor immune response. In this review, we discuss how metabolic regulators affect the tumor cell and the crosstalk of TME. We also summarize recent clinical trials involving metabolic regulators and the challenges of metabolism-based tumor therapies in clinical translation. In a word, our review distills key regulatory factors and their mechanisms of action from the complex reprogramming of tumor metabolism, identified as tumor metabolic regulators. These regulators provide a theoretical basis and research direction for the development of new strategies and targets in cancer therapy based on tumor metabolic reprogramming.

CD137-expressing regulatory T cells in cancer and autoimmune diseases

Regulatory T cells (Tregs) are essential for maintaining immune homeostasis, with critical roles in preventing aberrant immune responses that occur in autoimmune diseases and chronic inflammation. Conversely, the abundance of Tregs in cancer is associated with impaired anti-tumor immunity, and tumor immune evasion. Recent work demonstrates that CD137, a well-known costimulatory molecule for T cells, is highly expressed on Tregs in pathological conditions, while its expression is minimal or negligible on peripheral Tregs. The expression of CD137 marks Tregs with potent immunosuppressive phenotype that foster cancer progression and are protective against certain autoimmune diseases. Hence CD137 has emerged as a marker for Tregs. However, several important questions still remain regarding the expression and function of CD137 in Tregs. Here, we provide an overview of our current knowledge of Treg mechanisms of action, with a focus on the role of CD137 in modulating Treg activity. We also explore the implications of CD137+ Tregs in both cancer and autoimmune diseases, emphasizing the significance of targeting these cells for therapeutic intervention in these conditions.

Metabolic Signaling in the Tumor Microenvironment

Cancer cells must reprogram their metabolism to sustain rapid growth. This is accomplished in part by switching to aerobic glycolysis, uncoupling glucose from mitochondrial metabolism, and performing anaplerosis via alternative carbon sources to replenish intermediates of the tricarboxylic acid (TCA) cycle and sustain oxidative phosphorylation (OXPHOS). While this metabolic program produces adequate biosynthetic intermediates, reducing agents, ATP, and epigenetic remodeling cofactors necessary to sustain growth, it also produces large amounts of byproducts that can generate a hostile tumor microenvironment (TME) characterized by low pH, redox stress, and poor oxygenation. In recent years, the focus of cancer metabolic research has shifted from the regulation and utilization of cancer cell-intrinsic pathways to studying how the metabolic landscape of the tumor affects the anti-tumor immune response. Recent discoveries point to the role that secreted metabolites within the TME play in crosstalk between tumor cell types to promote tumorigenesis and hinder the anti-tumor immune response. In this review, we will explore how crosstalk between metabolites of cancer cells, immune cells, and stromal cells drives tumorigenesis and what effects the competition for resources and metabolic crosstalk has on immune cell function.

Identification of fatty acid anabolism patterns to predict prognosis and immunotherapy response in gastric cancer

Gastric cancer (GC), one of the most common and heterogeneous malignancies, is the second leading cause of cancer death worldwide and is closely related to dietary habits. Fatty acid is one of the main nutrients of human beings, which is closely related to diabetes, hypertension and other diseases. However, the correlation between fatty acid metabolism and the development and progression of GC remains largely unknown. Here, we profiled the genetic alterations of fatty acid anabolism-related genes (FARGs) in gastric cancer samples from the TCGA cohort and GEO database to evaluate the possible relationships and their internal regulatory mechanism. Through consistent clustering and functional enrichment analysis, three distinct fatty acid anabolism clusters and three gene subtypes were identified to participate in different biological pathways, and correlated with the characteristics of immune cell infiltration and clinical prognosis. Importantly, a distinctive FA-score was constructed through the principal component analysis to quantify the characteristics of fatty acid anabolism in each GC patient. Further analysis showed patients grouped in the high FA-score group were characterized with greater tumor mutational burden (TMB) and higher microsatellite stability (MSI-H), which may be more aeschynomenous to immunotherapy and had a favorable prognosis. Altogether, our bioinformatics analysis based on FARGs uncovered the potential roles of fatty acid metabolism in GC, and may provide newly prognostic information and novel approaches for promoting individualized immunotherapy in patients with GC.

β-receptor blocker enhances anti-tumor immunity via inhibiting lactate-induced norepinephrine metabolism of macrophages during malignant pleural effusion

Introduction

Malignant pleural effusion (MPE) is associated with poor quality of life and mortality in patients with tumors. In clinical practice, we observed that patients with malignant pleural effusion (MPE) and concurrent heart disease exhibited a decrease in MPE volumes following treatment with β-receptor blockers for heart disease. Immunosuppressive tumor microenvironment was found to play a substantial role in the progression of MPE, and mainly attributed to tumor-associated macrophages (TAMs). However, whether β-receptor blockers improve MPE through affecting the immune microenvironment especially TAMs and the potential mechanism behind remains unclear.

Methods

In this study, we collected the MPE samples from MPE and heart disease patients treated with propranolol, and performed flow cytometry experiment to evaluate the effect of propranolol on MPE immune microenvironment. Then, the mechanism that how propranolol effectively reprogrammed the immunosuppressive microenvironment of MPE was conducted by the experiments of mass spectrometry, RNA-seq, flow cytometry, immunofluorescence, western blotting, etc. Lastly, to further evaluate the effect of propranolol on MPE therapy in vivo, we developed a mouse model of MPE. We administrated propranolol into MPE-bearing mice to investigate the therapy efficacy and the changes of MPE microenvironment by the experiments of computed tomography (CT) scanning, flow cytometry, etc.

Results

We observed that propranolol treatment in MPE patients with heart disease decreased TAM frequency and immunosuppression and enhanced anti-tumor immunity. Macrophages in MPE exhibited an immunosuppressive phenotype via the activation of norepinephrine metabolism. Subsequently, we found that lactate was increased in MPE and may contribute to an increase in TAM frequency and inhibition of anti-tumor immunity by macrophages. Additionally, lactate triggered phenylalanine/norepinephrine signaling and further induced macrophage immunosuppression in an ERK-depended way. Lastly, in the MPE mouse model, propranolol inhibited MPE development and reversed the immune microenvironment of MPE.

Discussion

Here, we reveal the mechanism by which lactate induces macrophage immunosuppression via activating phenylalanine/norepinephrine signaling. Our findings highlight that blocking norepinephrine signaling by β-receptor blockers is an attractive therapeutic strategy to enhance anti-tumor immunity in the context of MPE.

Tumor-Selective Nano-Dispatcher Enforced Cancer Immunotherapeutic Effects via Regulating Lactate Metabolism and Activating Toll-Like Receptors

The development of tumors relies on lactate metabolic reprogramming to facilitate their unchecked growth and evade immune surveillance. This poses a significant challenge to the efficacy of antitumor immunity. To address this, a tumor-selective nano-dispatcher, PIMDQ/Syro-RNP, to enforce the immunotherapeutic effect through regulation of lactate metabolism and activation of toll-like receptors is developed. By using the tumor-targeting properties of c-RGD, the system can effectively deliver monocarboxylate transporters 4 (MCT4) inhibitor (Syro) to inhibit lactate efflux in tumor cells, leading to decreased lactate levels in the tumor microenvironment (TME) and increased accumulation within tumor cells. The reduction of lactate in TME will reduce the nutritional support for regulatory T cells (Tregs) and promote the effector function of T cells. The accumulation of lactate in tumor cells will lead to tumor death due to cellular acidosis. In addition, it will also reduce the uptake of glucose by tumor cells, reduce nutrient plunder, and further weaken the inhibition of T cell function. Furthermore, the pH-responsive release of Toll-like receptors (TLR) 7/8 agonist IMDQ within the TME activates dendritic cells (DCs) and promotes the infiltration of T cells. These findings offer a promising approach for enhancing tumor immune response through targeted metabolic interventions.

Engineered Biomimetic Cancer Cell Membrane Nanosystems Trigger Gas-Immunometabolic Therapy for Spinal-Metastasized Tumors

Despite great progress in enhancing tumor immunogenicity, conventional gas therapy cannot effectively reverse the tumor immunosuppressive microenvironment (TIME), limiting immunotherapy. The development of therapeutic gases that are tumor microenvironment responsive and efficiently reverse the TIME for precisely targeted tumor gas-immunometabolic therapy remains a great challenge. In this study, a novel cancer cell membrane-encapsulated pH-responsive nitric oxide (NO)-releasing biomimetic nanosystem (MP@AL) is prepared. Lactate oxidase (Lox) in MP@AL consumed oxygen to promote the decomposition of lactate, a metabolic by-product of tumor glycolysis, and the generation of H2O2, while L-arginine (L-Arg) in MP@AL is oxidized by H2O2 to generate nitric oxide (NO). For one thing, NO led to mitochondrial dysfunction in tumor cells to reduce oxygen consumption and promote the efficiency of Lox in lactate decomposition, thus reversing lactate-induced TIME; for another, NO effectively triggered immunogenic cell death, activated anti-tumor immune response and long-term immune memory, and ensured a favorable effect in the synergistic interaction with PD-L1 antibody for inhibiting tumor growth and recurrence. Therefore, a novel gas-immunometabolic therapy dual closed-loop nanosystem for enhancing tumor immunogenicity and remodeling lactate-induced TIME is established. Overall, this work will provide new ideas for gas therapy to effectively remodel the TIME to enhance cancer immunotherapy.

Why and how citrate may sensitize malignant tumors to immunotherapy

Immunotherapy, either alone or in combination with chemotherapy, has demonstrated limited efficacy in a variety of solid cancers. Several factors contribute to explaining primary or secondary resistance. Among them, cancer cells, whose metabolism frequently relies on aerobic glycolysis, promote exhaustion of cytotoxic immune cells by diverting the glucose in the tumor microenvironment (TME) to their own profit, while secreting lactic acid that sustains the oxidative metabolism of immunosuppressive cells. Here, we propose to combine current treatment based on the use of immune checkpoint inhibitors (ICIs) with high doses of sodium citrate (SCT) because citrate inhibits cancer cell metabolism (by targeting both glycolysis and oxidative metabolism) and may active anti-tumor immune response. Indeed, as showed in preclinical studies, SCT reduces cancer cell growth, promoting cell death and chemotherapy effectiveness. Furthermore, since the plasma membrane citrate carrier pmCIC is mainly expressed in cancer cells and low or not expressed in immune and non-transformed cells, we argue that the inhibition of cancer cell metabolism by SCT may increase glucose availability in the TME, thus promoting functionality of anti-tumor immune cells. Concomitantly, the decrease in the amount of lactic acid in the TME may reduce the functionality of immunosuppressive cells. Preclinical studies have shown that SCT can enhance the anti-tumor immune response through an enhancement of T cell infiltration and activation, and a repolarization of macrophages towards a TAM1-like phenotype. Therefore, this simple and cheap strategy may have a major impact to increase the efficacy of current immunotherapies in human solid tumors and we encourage testing it in clinical trials.

Mouse Models Enable the Functional Investigation of Tertiary Lymphoid Structures in Cancer

Tertiary lymphoid structures (TLSs) are organized lymphoid aggregates that form within nonlymphoid tissue, including tumors, in response to persistent inflammatory stimulation. In cancer patients, TLSs are generally associated with positive clinical outcomes. However, the cellular composition and spatial distribution of TLSs can vary depending on the underlying disease state, complicating interpretations of their prognostic significance. Murine models are indispensable for providing a deeper insight into the mechanisms involved in TLS formation and function. Studies using these models can complement current clinical efforts to characterize TLSs via genetic sequencing and histopathology of human samples. Several features of TLSs resemble that of secondary lymphoid organs (SLOs). Consequently, vascular system components and structural support elements are important for TLS formation and maintenance. Furthermore, TLSs in different tissue environments can exhibit distinct characteristics, necessitating careful consideration when selecting mouse models for study. Herein, we discuss critical aspects to consider when modeling TLSs and describe recent findings of TLS studies in the mouse lung and intestinal gut environments as examples to highlight the importance of considering tissue-specific regulatory mechanisms for TLSs. In this chapter, we also summarize the mechanistic insights derived from murine models on the formation and function of TLSs, which may translate to the future therapeutic modulation of TLS in disease.

Metabolism of cancer cells and immune cells in the initiation, progression, and metastasis of cancer

The metabolism of cancer and immune cells plays a crucial role in the initiation, progression, and metastasis of cancer. Cancer cells often undergo metabolic reprogramming to sustain their rapid growth and proliferation, along with meeting their energy demands and biosynthetic needs. Nevertheless, immune cells execute their immune response functions through the specific metabolic pathways, either to recognize, attack, and eliminate cancer cells or to promote the growth or metastasis of cancer cells. The alteration of cancer niches will impact the metabolism of both cancer and immune cells, modulating the survival and proliferation of cancer cells, and the activation and efficacy of immune cells. This review systematically describes the key characteristics of cancer cell metabolism and elucidates how such metabolic traits influence the metabolic behavior of immune cells. Moreover, this article also highlights the crucial role of immune cell metabolism in anti-tumor immune responses, particularly in priming T cell activation and function. By comprehensively exploring the metabolic crosstalk between cancer and immune cells in cancer niche, the aim is to discover novel strategies of cancer immunotherapy and provide effective guidance for clinical research in cancer treatment. In addition, the review also discusses current challenges such as the inadequacy of relevant diagnostic technologies and the issue of multidrug resistance, and proposes potential solutions including bolstering foundational cancer research, fostering technological innovation, and implementing precision medicine approaches. In-depth research into the metabolic effects of cancer niches can improve cancer treatment outcomes, prolong patients' survival period and enhance their quality of life.

Stemness in solid malignancies: coping with immune attack

Immunotherapy has become a key new pillar of cancer treatment, and this has sparked interest in understanding mechanisms of cancer immune evasion. It has long been appreciated that cancers are constituted by heterogeneous populations of tumour cells. This feature is often fuelled by specialized cells that have molecular programs resembling tissue stem cells. Although these cancer stem cells (CSCs) have capacity for unlimited self-renewal and differentiation, it is increasingly evident that some CSCs are capable of achieving remarkable immune resistance. Given that most immunotherapy regiments have overlooked CSC-specific immune-evasive mechanisms, many current treatment strategies often lead to cancer relapse. This Review focuses on advancements in understanding how CSCs in solid tumours achieve their unique immune-evasive properties, enabling them to drive tumour regrowth. Moreover, as cancers often arise from tissue stem cells that acquired oncogenic mutations, we discuss how tissue stem cells undergoing malignant transformation activate intrinsic immune-evasive mechanisms and establish close interactions with suppressive immune cells to escape immune surveillance. In addition, we summarize how in advanced disease stages, CSCs often hijack features of normal stem cells to resist antitumour immunity. Finally, we provide insights in how to design a new generation of cancer immunotherapies to ensure elimination of CSCs.

A novel lineage-tracing tool reveals that hypoxic tumor cells drive tumor relapse after radiotherapy

PURPOSE

Tumor hypoxia imposes a main obstacle to the efficacy of anti-cancer therapy. Understanding the cellular dynamics of individual hypoxic cells before, during and post-treatment has been hampered by the technical inability to identify and trace these cells over time.

METHODS AND MATERIALS

Here, we present a novel lineage-tracing reporter for hypoxic cells based on the conditional expression of a HIF1a-CreERT2-UnaG biosensor that can visualize hypoxic cells in a time-dependent manner and trace the fate of hypoxic cells over time. We combine this system with multiphoton microscopy, flow cytometry, and immunofluorescence to characterize the role of hypoxic cells in tumor relapse after irradiation in H1299 tumor spheroids and in vivo xenografts.

RESULTS

We validate the reporter in monolayer cultures and we show that tagged cells colocalize in spheroids and human tumor xenografts with the hypoxic marker pimonidazole. We found that irradiation of H1299-HIFcreUnaG spheroids leads to preferential outgrowth of cells from the hypoxic core. Similarly, in xenografts tumors, although initially UnaG-positive-cells coincide with pimonidazole-positive tumor areas and they are merely quiescent, upon irradiation UnaG-positive cells enrich in regrowing tumors and are mainly proliferative.

CONCLUSIONS

Collectively, our data provide clear evidence that the hypoxic cells drive tumor relapse after irradiation.

Self-Assembly Nanomedicine Initiating Cancer-Immunity Cycle with Cascade Reactions for Boosted Immunotherapy

Immune checkpoint blockade (ICB) therapy has been extensively integrated into cancer clinical management. However, its overall response rate is limited due to the stagnating cancer-immunity cycle (CIC) caused by the immunosuppressive tumor microenvironment (TME). Here, a multi-pronged nanomedicine, defined as LCCS, was constructed by the self-assembly of lactate oxidase, catalase, chlorin e6, and sorafenib. Through cascade reactions, LCCS effectively reprogrammed the TME and re-initiated the CIC by depleting lactate, alleviating hypoxia, inducing immunogenic cell death, and normalizing tumor vessels. Immunological analyses indicated that treatment with LCCS decreased the infiltration of immunosuppressive cells while increasing the recruitment of immune effector cells in tumors. Leveraging the effective operation of the CIC, LCCS improved the efficacy of ICB therapy to inhibit breast cancer, and effectively induced the elimination of colorectal cancer and long-term immune memory. Therefore, multifunctional nanomedicines targeting CIC hold great potential for applications in cancer immunotherapy.

Changes in Treg cells and cytokines in the peripheral blood of patients with coronary artery disease combined with type 2 diabetes mellitus

BACKGROUND

Patients with coronary artery disease (CAD) combined with type 2 diabetes mellitus (T2DM) develop serious atherosclerotic and diffuse lesions. Inadequate numbers and the dysfunction of CD4+CD25+Foxp3+regulatory T lymphocytes (Treg cells) are common mechanisms underlying the immunopathological damage in CAD and T2DM.

OBJECTIVES

We aimed to explore Treg cell changes in patients with CAD complicated with T2DM and to investigate the association between Treg cells and the severity of CAD.

METHODS

A total of 257 participants were included in the study, divided into a healthy control group (HC, n = 63), CAD group (n = 106), and CAD complicated with T2DM group (CAD+T2DM, n = 88). Flow cytometry detected Treg cell levels, and serum IL-10, IL-6, and ELISA detected TGF-β.

RESULTS

The sample for this study consisted of 170 males and 87 females, with 88 (34.24 %) participants having diabetes and 169 (65.76 %) without diabetes. The proportion of circulating Treg cells was lower in the CAD and CAD+T2DM groups than in the HC group, and it was lower in the CAD+T2DM group than in the CAD group. The plasma levels of IL-10 and TGF-β were lower in the CAD than in the HC group, and the levels in the CAD+T2DM group were significantly lower than those in the CAD group. However, the plasma IL-6 level changed in the opposite direction. Gensini's score was negatively correlated with Treg cells (R = - 0.57, P < .05). Subgroup analyses and interaction analyses showed that the association of Treg with the Gensini score was robust.

CONCLUSION

The level of Treg cells was an independent protective factor for patients with CAD and T2DM and was negatively correlated with the Gensini score. Therefore, Treg cells may be used as therapeutic targets for CAD with T2DM patients.

Lactylation-driven TNFR2 expression in regulatory T cells promotes the progression of malignant pleural effusion

BACKGROUND

Although tumor necrosis factor receptor 2 (TNFR2) has been recognized as an attractive next-generation candidate target for cancer immunotherapy, the factors that regulate the gene expression and their mechanistic effects on tumor-infiltrating regulatory T cells (Treg cells) remain poorly understood.

METHODS

Single-cell RNA sequencing analysis was employed to analyze the phenotypic and functional differences between TNFR2+ Treg cells and TNFR2- Treg cells. Malignant pleural effusion (MPE) from humans and mouse was used to investigate the potential mechanisms by which lactate regulates TNFR2 expression.

RESULTS

Treg cells with high TNFR2 expression exhibited elevated levels of immune checkpoint molecules. Additionally, the high expression of TNFR2 on Treg cells was positively correlated with a poor prognosis in MPE patients. Moreover, we revealed that lactate upregulated TNFR2 expression on Treg cells, thereby enhancing their immunosuppressive function in MPE. Mechanistically, lactate modulated the gene transcription of transcription factor nuclear factor-κB p65 (NF-κB p65) through histone H3K18 lactylation (H3K18la), subsequently upregulating the gene expression of TNFR2 and expediting the progression of MPE. Notably, lactate metabolism blockade combined with immune checkpoint blockade (ICB) therapy effectively enhanced the efficacy of ICB therapy, prolonged the survival time of MPE mice, and improved immunosuppression in the microenvironment of MPE.

CONCLUSIONS

The study explains the mechanism that regulates TNFR2 expression on Treg cells and its function in MPE progression, providing novel insights into the epigenetic regulation of tumor development and metabolic strategies for MPE treatment by targeting lactate metabolism in Treg cells.

Metabolic reprogramming, sensing, and cancer therapy

The metabolic reprogramming of tumor cells is a crucial strategy for their survival and proliferation, involving tissue- and condition-dependent remodeling of certain metabolic pathways. While it has become increasingly clear that tumor cells integrate extracellular and intracellular signals to adapt and proliferate, nutrient and metabolite sensing also exert direct or indirect influences, although the underlying mechanisms remain incompletely understood. Furthermore, metabolic changes not only support the rapid growth and dissemination of tumor cells but also promote immune evasion by metabolically "educating" immune cells in the tumor microenvironment (TME). Recent studies have highlighted the profound impact of metabolic reprogramming on the TME and the potential of targeting metabolic pathways as a therapeutic strategy, with several enzyme inhibitors showing promising results in clinical trials. Thus, understanding how tumor cells alter their metabolic pathways and metabolically remodel the TME to support their survival and proliferation may offer new strategies for metabolic therapy and immunotherapy.

Lactate and Lactylation: Dual Regulators of T-Cell-Mediated Tumor Immunity and Immunotherapy

Lactate and its derivative, lactylation, play pivotal roles in modulating immune responses within the tumor microenvironment (TME), particularly in T-cell-mediated cancer immunotherapy. Elevated lactate levels, a hallmark of the Warburg effect, contribute to immune suppression through CD8+ T cell functionality and by promoting regulatory T cell (Treg) activity. Lactylation, a post-translational modification (PTM), alters histone and non-histone proteins, influencing gene expression and further reinforcing immune suppression. In the complex TME, lactate and its derivative, lactylation, are not only associated with immune suppression but can also, under certain conditions, exert immunostimulatory effects that enhance cytotoxic responses. This review describes the dual roles of lactate and lactylation in T-cell-mediated tumor immunity, analyzing how these factors contribute to immune evasion, therapeutic resistance, and immune activation. Furthermore, the article highlights emerging therapeutic strategies aimed at inhibiting lactate production or disrupting lactylation pathways to achieve a balanced regulation of these dual effects. These strategies offer new insights into overcoming tumor-induced immune suppression and hold the potential to improve the efficacy of cancer immunotherapies.

Tumor-infiltrating regulatory T cell: A promising therapeutic target in tumor microenvironment

ABSTRACT

Regulatory T cell (Tregs) predominantly maintain the immune balance and prevent autoimmunity via their immunosuppressive functions. However, tumor-infiltrating Tregs (TI-Tregs) may mediate tumor immune tolerance in complex tumor microenvironments, resulting in poor prognosis. Distinguishing specific TI-Treg subpopulations from peripheral Tregs and intratumoral conventional T cells (Tconvs) has recently emerged as an important topic in antitumor therapy. In this review, we summarize novel therapeutic approaches targeting both the metabolic pathways and hallmarks of TI-Tregs in preclinical and clinical studies. Although the phenotypic and functional diversity of TI-Tregs remains unclear, our review provides new insights into TI-Treg-based therapies and facilitates precision medicine for tumor treatment.