Cholesterol negatively regulates IL-9-producing CD8+ T cell differentiation and antitumor activity

Targeting γc family cytokines with biologics: current status and future prospects

Over the recent decades the market potential of biologics has substantially expanded, and many of the top-selling drugs worldwide are now monoclonal antibodies or antibody-like molecules. The common gamma chain (γc) cytokines, Interleukin (IL-)2, IL-4, IL-7, IL-9, IL-15, and IL-21, play pivotal roles in regulating immune responses, from innate to adaptive immunity. Dysregulation of cell signaling by these cytokines is strongly associated with a range of immunological disorders, which includes cancer as well as autoimmune and inflammatory diseases. Given the essential role of γc cytokines in maintaining immune homeostasis, the development of therapeutic interventions targeting these molecules poses unique challenges. Here, we provide an overview of current biologics targeting either single or multiple γc cytokines or their respective receptor subunits across a spectrum of diseases, primarily focusing on antibodies, antibody-like constructs, and antibody-cytokine fusions. We summarize therapeutic biologics currently in clinical trials, highlighting how they may offer advantages over existing therapies and standard of care, and discuss recent advances in this field. Finally, we explore future directions and the potential of novel therapeutic intervention strategies targeting this cytokine family.

Adoptively transferred tumor-specific IL-9-producing cytotoxic CD8+ T cells activate host CD4+ T cells to control tumors with antigen loss

Host effector CD4+ T cells emerge as critical mediators for tumor regression but whether they can be activated by adoptively transferred CD8+ T cells remains unknown. We previously reported that adoptive transfer of interleukin 9 (IL-9)-producing cytotoxic CD8+ T (Tc9) cells achieved long-term control of tumor growth. Here, we demonstrate that murine tumor-specific Tc9 cells control the outgrowth of antigen-loss relapsed tumors by recruiting and activating host effector CD4+ T cells. Tc9 cells secreted IL-24 and recruited CCR7-expressing conventional type 2 dendritic cells (cDC2 cells) into tumor-draining lymph nodes to prime host CD4+ T cells against relapsed tumors. Host CD4+ T cell or cDC2 deficiency impaired the ability of Tc9 cells to control relapsed tumor outgrowth. Additionally, intratumoral IL24 expression correlates with cDC2 and CD4+ T cell gene signatures in human cancers and their expression is associated with better patient survival. This study reports a mechanism for activation of tumor-specific CD4+ T cells in vivo.

Impact of rosuvastatin on the memory potential and functionality of CD8+ T cells from people with HIV

BACKGROUND

Virus-specific CD8+ T cells play a major role in the natural control of HIV infection, linked to memory-like features such as high survival capacity and polyfunctionality. However, virus-specific CD8+ T cells from HIV non-controllers exhibit an effector-like and exhausted profile, with limited antiviral potential. Metabolic reprogramming of cells from non-controllers could reinvigorate their functional capacities. Considering the implication of the cholesterol pathway in the induction of T cell exhaustion, here we evaluated the impact of rosuvastatin, an inhibitor of cholesterol synthesis, on the functionality and memory profile of HIV-specific CD8+ T cells from people on antiretroviral treatment.

METHODS

We analysed samples from 10 individuals with HIV-1 on ART who participated in the IMEA 043-CESAR trial and received rosuvastatin for 12 weeks. We explored whether rosuvastatin treatment was accompanied by changes in the memory potential of CD8+ T cells. We evaluated the phenotype and functionality of total and HIV-specific CD8+ T cells before, during, and after treatment with rosuvastatin. A mixed effects model was used for repeated measures and corrected for multiple comparisons.

FINDINGS

Total and HIV-specific CD8+ T cell survival and functionality were enhanced in individuals who received a 12-week course of rosuvastatin, with a consistent increase in polyfunctional IFN-γ+ TNF-α+ cells. The superior CD8+ T cell functionality after rosuvastatin treatment was associated with intrinsic metabolic changes, including the decrease of fatty acid uptake, as well as a reduction in effector/exhaustion markers. Changes in the characteristics of CD8+ T cells coincided with the duration of rosuvastatin administration, and most effects waned after the cessation of the treatment.

INTERPRETATION

CD8+ T cell metabolic reprogramming by targeting the cholesterol pathway, combined with other available immunotherapies, might represent a promising strategy in the search for the cure of HIV or other chronic viral infections.

FUNDING

The CESAR trial was sponsored by IMEA. This work was supported by the NIH (grants UM1AI164562 and R01DK131476).

Spatial genomics reveals cholesterol metabolism as a key factor in colorectal cancer immunotherapy resistance

Immune checkpoint inhibitors (ICIs) have transformed the treatment landscape across multiple cancer types achieving durable responses for a significant number of patients. Despite their success, many patients still fail to respond to ICIs or develop resistance soon after treatment. We sought to identify early treatment features associated with ICI outcome. We leveraged the MC38 syngeneic tumor model because it has variable response to ICI therapy driven by tumor intrinsic heterogeneity. ICI response was assessed based on the level of immune cell infiltration into the tumor - a well-established clinical hallmark of ICI response. We generated a spatial atlas of 48,636 transcriptome-wide spots across 16 tumors using spatial transcriptomics; given the tumors were difficult to profile, we developed an enhanced transcriptome capture protocol yielding high quality spatial data. In total, we identified 8 tumor cell subsets (e.g., proliferative, inflamed, and vascularized) and 4 stroma subsets (e.g., immune and fibroblast). Each tumor had orthogonal histology and bulk-RNA sequencing data, which served to validate and benchmark observations from the spatial data. Our spatial atlas revealed that increased tumor cell cholesterol regulation, synthesis, and transport were associated with a lack of ICI response. Conversely, inflammation and T cell infiltration were associated with response. We further leveraged spatially aware gene expression analysis, to demonstrate that high cholesterol synthesis by tumor cells was associated with cytotoxic CD8 T cell exclusion. Finally, we demonstrate that bulk RNA-sequencing was able to detect immune correlates of response but lacked the sensitivity to detect cholesterol synthesis as a feature of resistance.

Ferroptosis of T cell in inflammation and tumour immunity

Ferroptosis is an innovative concept defined as a distinct programmed cell death mode regulated by iron-dependent lipid peroxidation accumulation. This process is governed by numerous energy metabolites such as fatty acids, amino acids and glucose, as well as iron homeostasis. In recent years, increasing studies have been devoted to the crucial effects of ferroptosis in immune cells during the pathogenesis of diseases such as infections, tumours and autoimmune disorders. This review summarises the latest advancements in T-cell ferroptosis, addresses the key components and mechanism of ferroptosis in T cells during inflammatory conditions and tumour progression, and highlights the potential target for treating related diseases. KEY POINTS: Ferroptosis-related mechanisms significantly affect the biology of CD4+ T-cell subsets and are further involved in inflammatory diseases. Crosstalk between CD8+ T cells and tumour cells induces ferroptosis in the tumour microenvironment. Glutathione peroxidase 4 loss promotes regulatory T-cell ferroptosis to enhance anti-tumour immunity.

Modulating lipid metabolism improves tumor immunotherapy

Immunotherapy has progressed significantly in cancer treatment; however, several factors influence its outcomes. Abnormal lipid metabolism, which is frequently observed in cancers, promotes tumor proliferation, invasion, and metastasis. Li et al from the Medical Oncology Department of Chongqing University Cancer Hospital constructed a lipid metabolism scoring system and reported that MK1775 inhibited fatty acid oxidation in tumor-associated macrophages and reduced T-cell infiltration, further enhancing the efficacy of immunotherapy. This study demonstrated the critical role of lipid metabolism scoring system and lipid metabolism in immunotherapy. Currently, the metabolism of lipids, such as fatty acids, phospholipids, and cholesterol, has been reported to affect the tumor microenvironment by regulating immune cells, including T cells, natural killer cells, and macrophages. These metabolic changes can impair the efficacy of immunotherapy, resulting in tumor progression. Consequently, lipid metabolism emerges as an important immune regulator for improving immunotherapeutic outcomes and provides a novel and powerful strategy for tumor combination therapy.

Targeting piRNA-137463 Inhibits Tumor Progression and Boosts Sensitivity to Immune Checkpoint Blockade via De Novo Cholesterol Biosynthesis in Lung Adenocarcinoma

The important role of PIWI-interacting RNAs (piRNAs) in tumors has garnered increasing attention. However, research on their role in lung adenocarcinoma (LUAD) remains limited. Elevated levels of piRNA-137463 have been linked to poor prognosis in LUAD patients. Inhibition of piRNA-137463 curbed the proliferation, migration, and invasion of LUAD cells, enhanced T cell cytotoxicity through increased IFN-γ secretion, disrupted cholesterol metabolism, and reduced intracellular cholesterol, lipid raft content, and PD-L1 expression in LUAD cells. Bioinformatic prediction identified a potential interaction between piRNA-137463 and lncRNA LOC100128494. Inhibiting piRNA-137463 increased the stability and expression of LOC100128494, which further modulated insulin-induced gene 1 protein (INSIG1) levels via a competitive endogenous RNA network involving LOC100128494 and miR-24-3p. Notably, the effect of piRNA-137463 in LUAD cells is dependent on the expression of LOC100128494 and INSIG1. Inhibiting the expression of piRNA-137463 with AntagopiRNA-137463 suppressed tumor growth and metastasis via LOC100128494 in nude mice and enhanced the response of LUAD to anti-PD-1 therapy in immune-competent mice. In summary, this study elucidates the role of piRNA-137463 in the reprogramming of cholesterol metabolism, which drives the progression of LUAD, thereby identifying a new target for the comprehensive clinical management of LUAD.

A reappraisal of IL-9 in inflammation and cancer

While much is known about the functional effects of type 2 cytokines interleukin (IL)-4, IL-5 and IL-13 in homeostasis and disease, we still poorly understand the functions of IL-9. Chronic inflammation seen in allergic diseases, autoimmunity and cancer is however frequently accompanied by overproduction of this elusive type 2 cytokine. Initially identified as a T cell and mast cell growth factor, and later as the hallmark cytokine defining TH9 cells, we now know that IL-9 is produced by multiple innate and adaptive immune cells. Recent evidence suggests that IL-9 controls discrete aspects of the allergic cascade, cellular responses of immune and stromal cells, cancer progression, tolerance and immune escape. Despite functioning as a pleiotropic cytokine in mucosal environments, like the lungs, the direct and indirect cellular targets of IL-9 are still not well characterized. Here, we discuss IL-9's cellular senders and receivers, focusing on asthma and cancer. Moreover, we review current research directions and the outlook of targeted therapy centered around the biology of IL-9.

Targeting T cell exhaustion: emerging strategies in non-small cell lung cancer

Lung cancer continues to be a major contributor to cancer-related deaths globally. Recent advances in immunotherapy have introduced promising treatments targeting T cell functionality. Central to the efficacy of these therapies is the role of T cells, which are often rendered dysfunctional due to continuous antigenic stimulation in the tumor microenvironment-a condition referred to as T cell exhaustion. This review addresses the critical challenge of T cell exhaustion in non-small cell lung cancer (NSCLC), offering a detailed examination of its molecular underpinnings and the resultant therapeutic ineffectiveness. We synthesize current knowledge on the drivers of T cell exhaustion, evaluate emerging strategies for its reversal, and explore the potential impact of these insights for enhancing the clinical efficacy of immunotherapies. By consolidating reported clinical trials and preclinical studies, this article highlights innovative approaches to modulate immune responses and improve patient outcomes, thus providing a roadmap for future research and therapeutic development in lung cancer immunotherapy.

Functional diversity and regulation of IL-9-producing T cells in cancer immunotherapy

IL-9-producing T cells (T9) regulate immunological responses that affect various cellular biological processes, though their precise function remains fully understood. Previous studies have linked T9 cells to conditions such as allergic disorders, parasitic infection clearance, and various types of cancers. While the functional heterogeneity of IL-9 and T9 cells in cancer development has been documented, these cells present promising therapeutic opportunities for treating solid tumors. This review highlights the roles of IL-9 and T9 cells in cancer progression and treatment responses, focusing on potential discrepancies in IL-9/IL-9R signaling between murine tumors and cancer patients. Additionally, we discuss the regulation of tumor-specific Th9/Tc9 cell differentiation, the therapeutic potential of these cells, and current strategies to enhance their anti-tumor activities.

Ferroptosis and the tumor microenvironment

Ferroptosis is a type of regulated cell death characterized by its non-apoptotic, iron-dependent and oxidative nature. Since its discovery in 2012, extensive research has demonstrated its pivotal roles in tumorigenesis, metastasis and cancer therapy. The tumor microenvironment (TME) is a complex ecosystem comprising cancer cells, non-cancer cells, extracellular matrix, metabolites and cytokines. Recent studies have underscored a new paradigm in which non-cancer cells in the TME, such as immune and stromal cells, also play significant roles in regulating tumor progression and therapeutic resistance typically through complicated crosstalk with cancer cells. Notably, this crosstalk in the TME were partially mediated through ferrotopsis-related mechanisms. This review provides a comprehensive and systematic summary of the current findings concerning the roles of ferroptosis in the TME and how ferroptosis-mediated TME reprogramming impacts cancer therapeutic resistance and progression. Additionally, this review outlines various ferroptosis-related therapeutic strategies aimed at targeting the TME.

Regulation of CD8+ T cells by lipid metabolism in cancer progression

Dysregulation of lipid metabolism is a key characteristic of the tumor microenvironment, where tumor cells utilize lipids for proliferation, survival, metastasis, and evasion of immune surveillance. Lipid metabolism has become a critical regulator of CD8+ T-cell-mediated antitumor immunity, with excess lipids in the tumor microenvironment impeding CD8+ T-cell activities. Considering the limited efficacy of immunotherapy in many solid tumors, targeting lipid metabolism to enhance CD8+ T-cell effector functions could significantly improve immunotherapy outcomes. In this review, we examine recent findings on how lipid metabolic processes, including lipid uptake, synthesis, and oxidation, regulate CD8+ T cells within tumors. We also assessed the impact of different lipids on CD8+ T-cell-mediated antitumor immunity, with a particular focus on how lipid metabolism affects mitochondrial function in tumor-infiltrating CD8+ T cells. Furthermore, as cancer is a systemic disease, we examined systemic factors linking lipid metabolism to CD8+ T-cell effector function. Finally, we summarize current therapeutic approaches that target lipid metabolism to increase antitumor immunity and enhance immunotherapy. Understanding the molecular and functional interplay between lipid metabolism and CD8+ T cells offers promising therapeutic opportunities for cancer treatment.

Fatty acid metabolism constrains Th9 cell differentiation and antitumor immunity via the modulation of retinoic acid receptor signaling

T helper 9 (Th9) cells are interleukin 9 (IL-9)-producing cells that have diverse functions ranging from antitumor immune responses to allergic inflammation. Th9 cells differentiate from naïve CD4+ T cells in the presence of IL-4 and transforming growth factor-beta (TGF-β); however, our understanding of the molecular basis of their differentiation remains incomplete. Previously, we reported that the differentiation of another subset of TGF-β-driven T helper cells, Th17 cells, is highly dependent on de novo lipid biosynthesis. On the basis of these findings, we hypothesized that lipid metabolism may also be important for Th9 cell differentiation. We therefore investigated the differentiation and function of mouse and human Th9 cells in vitro under conditions of pharmacologically or genetically induced deficiency of the intracellular fatty acid content and in vivo in mice genetically deficient in acetyl-CoA carboxylase 1 (ACC1), an important enzyme for fatty acid biosynthesis. Both the inhibition of de novo fatty acid biosynthesis and the deprivation of environmental lipids augmented differentiation and IL-9 production in mouse and human Th9 cells. Mechanistic studies revealed that the increase in Th9 cell differentiation was mediated by the retinoic acid receptor and the TGF-β-SMAD signaling pathways. Upon adoptive transfer, ACC1-inhibited Th9 cells suppressed tumor growth in murine models of melanoma and adenocarcinoma. Together, our findings highlight a novel role of fatty acid metabolism in controlling the differentiation and in vivo functions of Th9 cells.

Protective Role of High-Density Lipoprotein in Multiple Sclerosis

Multiple sclerosis (MS) is a chronic, progressive demyelinating disease with a most likely autoimmune background and a neurodegenerative component. Besides the demyelinating process caused by autoreactive antibodies, an increased permeability in the blood-brain barrier (BBB) also plays a key role. Recently, there has been growing interest in assessing lipid profile alterations in patients with MS. As a result of myelin destruction, there is an increase in the level of cholesterol released from cells, which in turn causes disruptions in lipid metabolism homeostasis both in the central nervous system (CNS) and peripheral tissues. Currently, there is a growing body of evidence suggesting a protective role of HDL in MS through its effect on the BBB by decreasing its permeability. This follows from the impact of HDL on the endothelium and its anti-inflammatory effect, mostly by interacting with adhesion molecules like vascular cell adhesion molecule 1 (VCAM-1), intercellular adhesion molecule 1 (ICAM-1), and E-selectin. HDL, through its action via sphingosine-1-phosphate, exerts an inhibitory effect on leukocyte migration, and its antioxidant properties contribute to the improvement of the BBB function. In this review, we want to summarize these studies and focus on HDL as a mediator of the anti-inflammatory response in MS.

Causal links between circulatory inflammatory cytokines and risk of digestive polyps: a Mendelian randomization analysis

Background

There is a high morbidity of polyps in the digestive tract, and certain subtypes of polyps are thought to induce cancer progression and often recur, which may be associated with chronic inflammation. Mendelian randomization (MR) can help identify potential causative relationships and inform early treatment action.

Methods

We performed a bidirectional two-sample MR analysis implementing the results from genome-wide association studies for 41 serum cytokines from 8,293 Finnish individuals, and three types of polyps from European ancestry, respectively, including gastric polyp (6,155 cases vs. 341,871 controls), colonic polyp (22,049 cases vs. 332,368 controls) and gallbladder polyp (458 cases vs. 340,083 controls). Inverse-variance weighted (IVW), weight median (WM), and MR-Egger methods were used for calculating causal estimates. Furthermore, Bayesian model averaging MR (MR-BMA) method was employed to detect the dominant causal circulatory cytokines with adjustment for pleiotropy effects.

Results

Our univariable MR using inverse-variance weight method identified causal associations of IL-2ra (OR: 0.892, 95%CI: 0.828-0.961, p = 0.003), MIG (OR: 1.124, 95%CI: 1.046-1.207, p = 0.001) and IL-18 (OR: 0.912, 95%CI: 0.852-0.977, p = 0.008) with gastric polyp, MIP1b (OR: 0.956, 95%CI: 0.927-0.987, p = 0.005) and IL-6 (OR: 0.931, 95%CI: 0.870-0.995, p = 0.035) with colonic polyp and IL-9 (OR: 0.523, 95%CI: 0.345-0.794, p = 0.0007) with gallbladder polyp. Finally, our MR-BMA analysis prioritized MIG (MIP = 0.332, MACE = 0.022; PP: 0.264, MSCE = 0.059), IL-18 (MIP = 0.302, MACE = -0.020; PP: 0.243, MSCE = -0.059) and IL-2ra (MIP: 0.129; MACE: -0.005; PP: 0.112, MSCE: -0.031) for gastric polyp, and MIP1b (MIP = 0.752, MACE = -0.033; PP: 0.665, MSCE = -0.044) and IL-6 (MIP: 0.196; MACE: -0.012; PP: 0.140, MSCE: -0.064) for colonic polyp, and IL-9 (MIP = 0.936, MACE = -0.446; PP: 0.781, MSCE = -0.478) for gallbladder polyp as the top-ranked protective factors.

Conclusion

Our research advances the current understanding of the function of certain inflammatory biomarker pathways in the genesis and malignant mutation of polyps in the digestive tract. Deeper substantiation is necessary to assess the potential of these cytokines as pharmacological or lifestyle targets for digestive polyps prevention.

Cholesterol inhibition enhances antitumor response of gilteritinib in lung cancer cells

Repositioning approved antitumor drugs for different cancers is a cost-effective approach. Gilteritinib was FDA-approved for the treatment of FLT3-mutated acute myeloid leukemia in 2018. However, the therapeutic effects and mechanism of Gilteritinib on other malignancies remain to be defined. In this study, we identified that gilteritinib has an inhibitory effect on lung cancer cells (LCCs) without FLT3 mutation in vitro and in vivo. Unexpectedly, we found that gilteritinib induces cholesterol accumulation in LCCs via upregulating cholesterol biosynthetic genes and inhibiting cholesterol efflux. This gilteritinib-induced cholesterol accumulation not only attenuates the antitumor effect of gilteritinib but also induces gilteritinib-resistance in LCCs. However, when cholesterol synthesis was prevented by squalene epoxidase (SQLE) inhibitor NB-598, both LCCs and gilteritinib-resistant LCCs became sensitive to gilteritinib. More importantly, the natural cholesterol inhibitor 25-hydroxycholesterol (25HC) can suppress cholesterol biosynthesis and increase cholesterol efflux in LCCs. Consequently, 25HC treatment significantly increases the cytotoxicity of gilteritinib on LCCs, which can be rescued by the addition of exogenous cholesterol. In a xenograft model, the combination of gilteritinib and 25HC showed significantly better efficacy than either monotherapy in suppressing lung cancer growth, without obvious general toxicity. Thus, our findings identify an increase in cholesterol induced by gilteritinib as a mechanism for LCC survival, and highlight the potential of combining gilteritinib with cholesterol-lowering drugs to treat lung cancer.

Metabolic dialogues: regulators of chimeric antigen receptor T cell function in the tumor microenvironment

Tumor-infiltrating lymphocytes (TILs) and chimeric antigen receptor (CAR) T cells have demonstrated remarkable success in the treatment of relapsed/refractory melanoma and hematological malignancies, respectively. These treatments have marked a pivotal shift in cancer management. However, as "living drugs," their effectiveness is dependent on their ability to proliferate and persist in patients. Recent studies indicate that the mechanisms regulating these crucial functions, as well as the T cell's differentiation state, are conditioned by metabolic shifts and the distinct utilization of metabolic pathways. These metabolic shifts, conditioned by nutrient availability as well as cell surface expression of metabolite transporters, are coupled to signaling pathways and the epigenetic landscape of the cell, modulating transcriptional, translational, and post-translational profiles. In this review, we discuss the processes underlying the metabolic remodeling of activated T cells, the impact of a tumor metabolic environment on T cell function, and potential metabolic-based strategies to enhance T cell immunotherapy.

Fatty acid oxidation in immune function

Cellular metabolism is a crucial determinant of immune cell fate and function. Extensive studies have demonstrated that metabolic decisions influence immune cell activation, differentiation, and cellular capacity, in the process impacting an organism's ability to stave off infection or recover from injury. Conversely, metabolic dysregulation can contribute to the severity of multiple disease conditions including autoimmunity, alloimmunity, and cancer. Emerging data also demonstrate that metabolic cues and profiles can influence the success or failure of adoptive cellular therapies. Importantly, immunometabolism is not one size fits all; and different immune cell types, and even subdivisions within distinct cell populations utilize different metabolic pathways to optimize function. Metabolic preference can also change depending on the microenvironment in which cells are activated. For this reason, understanding the metabolic requirements of different subsets of immune cells is critical to therapeutically modulating different disease states or maximizing cellular function for downstream applications. Fatty acid oxidation (FAO), in particular, plays multiple roles in immune cells, providing both pro- and anti-inflammatory effects. Herein, we review the major metabolic pathways available to immune cells, then focus more closely on the role of FAO in different immune cell subsets. Understanding how and why FAO is utilized by different immune cells will allow for the design of optimal therapeutic interventions targeting this pathway.

Value of prognostic nutritional index and controlling nutritional status score for advanced non-small cell lung cancer patients receiving PD-1 inhibitors

OBJECTIVE

To explore the value of preoperative prognostic nutritional index (PNI) and controlling nutritional status (CONUT) score in predicting response and prognosis of patients with advanced non-small cell lung cancer (NSCLC) receiving programmed cell death protein 1 (PD-1) inhibitors.

METHODS

A retrospective study was conducted in patients who received PD-1 inhibitors for advanced NSCLC. Patients were assigned by immunotherapy effects into response (partial and complete response, pCR) group (n=52) and non-response (non-pCR) group (n=132). The pathological and clinical data were collected for statistical analysis of factors influencing the immunotherapeutic response. The diagnostic value of PNI and CONUT score for response was assessed. The overall survival (OS) was observed over a 3-year follow-up. COX regression analysis was performed to identify risk factors affecting the survival. The effects of different PNI and CONUT scores on the survival were observed.

RESULTS

Multivariate regression analysis showed that, the tumor-node-metastasis (TNM) stage (P=0.001), PNI (P<0.001), and CONUT score (P<0.001) were associated with response. The non-pCR group had a higher 3-year mortality rate and a shorter 3-year OS than the pCR group (P<0.001). COX regression analysis showed that low PNI and high CONUT score were risk factors for poor prognosis. Further analysis showed that patients with low PNI and high CONUT score had lower 3-year survival rates (P=0.005, P<0.001).

CONCLUSION

High TNM stage, PNI<50, and CONUT score ≥5 are risk factors for poor response in patients with advanced NSCLC receiving PD-1 inhibitors, and low PNI and high CONUT score suggest poor prognosis.

Distinctive tumorigenic significance and innovative oncology targets of SUMOylation

Protein SUMOylation, a post-translational modification, intricately regulates diverse biological processes including gene expression, cell cycle progression, signaling pathway transduction, DNA damage response, and RNA metabolism. This modification contributes to the acquisition of tumorigenicity and the maintenance of cancer hallmarks. In malignancies, protein SUMOylation is triggered by various cellular stresses, promoting tumor initiation and progression. This augmentation is orchestrated through its specific regulatory mechanisms and characteristic biological functions. This review focuses on elucidating the fundamental regulatory mechanisms and pathological functions of the SUMO pathway in tumor pathogenesis and malignant evolution, with particular emphasis on the tumorigenic potential of SUMOylation. Furthermore, we underscore the potential therapeutic benefits of targeting the SUMO pathway, paving the way for innovative anti-tumor strategies by perturbing this dynamic and reversible modifying process.

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.

Cancer and Cardiovascular Disease: The Conjoined Twins

Cancer and cardiovascular disease are the two most common causes of death worldwide. As the fields of cardiovascular medicine and oncology continue to expand, the area of overlap is becoming more prominent demanding dedicated attention and individualized patient care. We have come to realize that both fields are inextricably intertwined in several aspects, so much so that the mere presence of one, with its resultant downstream implications, has an impact on the other. Nonetheless, cardiovascular disease and cancer are generally approached independently. The focus that is granted to the predominant pathological entity (either cardiovascular disease or cancer), does not allow for optimal medical care for the other. As a result, ample opportunities for improvement in overall health care are being overlooked. Herein, we hope to shed light on the interconnected relationship between cardiovascular disease and cancer and uncover some of the unintentionally neglected intricacies of common cardiovascular therapeutics from an oncologic standpoint.

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.

Metabolic plasticity of T cell fate decision

ABSTRACT

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

Cholesterol metabolism in tumor microenvironment: cancer hallmarks and therapeutic opportunities

Cholesterol is crucial for cell survival and growth, and dysregulation of cholesterol homeostasis has been linked to the development of cancer. The tumor microenvironment (TME) facilitates tumor cell survival and growth, and crosstalk between cholesterol metabolism and the TME contributes to tumorigenesis and tumor progression. Targeting cholesterol metabolism has demonstrated significant antitumor effects in preclinical and clinical studies. In this review, we discuss the regulatory mechanisms of cholesterol homeostasis and the impact of its dysregulation on the hallmarks of cancer. We also describe how cholesterol metabolism reprograms the TME across seven specialized microenvironments. Furthermore, we discuss the potential of targeting cholesterol metabolism as a therapeutic strategy for tumors. This approach not only exerts antitumor effects in monotherapy and combination therapy but also mitigates the adverse effects associated with conventional tumor therapy. Finally, we outline the unresolved questions and suggest potential avenues for future investigations on cholesterol metabolism in relation to cancer.

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.

Lipid metabolism in the immune niche of tumor-prone liver microenvironment

The liver is a common primary site not only for tumorigenesis, but also for cancer metastasis. Advanced cancer patients with liver metastases also show reduced response rates and survival benefits when treated with immune checkpoint inhibitors. Accumulating evidence has highlighted the importance of the liver immune microenvironment in determining tumorigenesis, metastasis-organotropism, and immunotherapy resistance. Various immune cells such as T cells, natural killer and natural killer T cells, macrophages and dendritic cells, and stromal cells including liver sinusoidal endothelial cells, Kupffer cells, hepatic stellate cells, and hepatocytes are implicated in contributing to the immune niche of tumor-prone liver microenvironment. In parallel, as the major organ for lipid metabolism, the increased abundance of lipids and their metabolites is linked to processes crucial for nonalcoholic fatty liver disease and related liver cancer development. Furthermore, the proliferation, differentiation, and functions of hepatic immune and stromal cells are also reported to be regulated by lipid metabolism. Therefore, targeting lipid metabolism may hold great potential to reprogram the immunosuppressive liver microenvironment and synergistically enhance the immunotherapy efficacy in the circumstance of liver metastasis. In this review, we describe how the hepatic microenvironment adapts to the lipid metabolic alterations in pathologic conditions like nonalcoholic fatty liver disease. We also illustrate how these immunometabolic alterations promote the development of liver cancers and immunotherapy resistance. Finally, we discuss the current therapeutic options and hypothetic combination immunotherapies for the treatment of advanced liver cancers.

DHCR24 in Tumor Diagnosis and Treatment: A Comprehensive Review

As an important nutrient in the human body, cholesterol can not only provide structural components for the body's cells, but also can be transformed into a variety of active substances to regulate cell signaling pathways. As an important cholesterol synthase, DHCR24 participates in important regulatory processes in the body. The application of DHCR24 in tumor clinical diagnosis and treatment also attracts much attention. This article reviews the structure and regulatory characteristics of DHCR24, and the research of DHCR24 on tumor progression. We summarize the possible mechanisms of DHCR24 promoting tumor progression through reactive oxygen species (ROS), p53, Ras and PI3K-AKT pathways. Through our review, we hope to provide more research ideas and reference value for the application of DHCR24 in tumor prevention and treatment.

Intracavitary Spraying of Nanoregulator-Encased Hydrogel Modulates Cholesterol Metabolism of Glioma-Supportive Macrophage for Postoperative Glioblastoma Immunotherapy

Glioblastoma multiforme (GBM) is notoriously resistant to immunotherapy due to its intricate immunosuppressive tumor microenvironment (TME). Dysregulated cholesterol metabolism is implicated in the TME and promotes tumor progression. Here, it is found that cholesterol levels in GBM tissues are abnormally high, and glioma-supportive macrophages (GSMs), an essential "cholesterol factory", demonstrate aberrantly hyperactive cholesterol metabolism and efflux, providing cholesterol to fuel GBM growth and induce CD8+ T cells exhaustion. Bioinformatics analysis confirms that high 7-dehydrocholesterol reductase (DHCR7) level in GBM tissues associates with increased cholesterol biosynthesis, suppressed tumoricidal immune response, and poor patient survival, and DHCR7 expression level is significantly elevated in GSMs. Therefore, an intracavitary sprayable nanoregulator (NR)-encased hydrogel system to modulate cholesterol metabolism of GSMs is reported. The degradable NR-mediated ablation of DHCR7 in GSMs effectively suppresses cholesterol supply and activates T-cell immunity. Moreover, the combination of Toll-like receptor 7/8 (TLR7/8) agonists significantly promotes GSM polarization to antitumor phenotypes and ameliorates the TME. Treatment with the hybrid system exhibits superior antitumor effects in the orthotopic GBM model and postsurgical recurrence model. Altogether, the findings unravel the role of GSMs DHCR7/cholesterol signaling in the regulation of TME, presenting a potential treatment strategy that warrants further clinical trials.

Targeting cholesterol metabolism in Cancer: From molecular mechanisms to therapeutic implications

Cholesterol is an essential component of cell membranes and helps to maintain their structure and function. Abnormal cholesterol metabolism has been linked to the development and progression of tumors. Changes in cholesterol metabolism triggered by internal or external stimuli can promote tumor growth. During metastasis, tumor cells require large amounts of cholesterol to support their growth and colonization of new organs. Recent research has shown that cholesterol metabolism is reprogrammed during tumor development, and this can also affect the anti-tumor activity of immune cells in the surrounding environment. However, identifying the specific targets in cholesterol metabolism that regulate cancer progression and the tumor microenvironment is still a challenge. Additionally, exploring the potential of combining statin drugs with other therapies for different types of cancer could be a worthwhile avenue for future drug development. In this review, we focus on the molecular mechanisms of cholesterol and its derivatives in cell metabolism and the tumor microenvironment, and discuss specific targets and relevant therapeutic agents that inhibit aspects of cholesterol homeostasis.

CD8 T-cell subsets: heterogeneity, functions, and therapeutic potential

CD8 T cells play crucial roles in immune surveillance and defense against infections and cancer. After encountering antigenic stimulation, naïve CD8 T cells differentiate and acquire effector functions, enabling them to eliminate infected or malignant cells. Traditionally, cytotoxic T cells, characterized by their ability to produce effector cytokines and release cytotoxic granules to directly kill target cells, have been recognized as the constituents of the predominant effector T-cell subset. However, emerging evidence suggests distinct subsets of effector CD8 T cells that each exhibit unique effector functions and therapeutic potential. This review highlights recent advancements in our understanding of CD8 T-cell subsets and the contributions of these cells to various disease pathologies. Understanding the diverse roles and functions of effector CD8 T-cell subsets is crucial to discern the complex dynamics of immune responses in different disease settings. Furthermore, the development of immunotherapeutic approaches that specifically target and regulate the function of distinct CD8 T-cell subsets holds great promise for precision medicine.

Mitogen-Activated Protein Kinase and Exploratory Nuclear Receptor Crosstalk in Cancer Immunotherapy

The three major mitogen-activated protein kinase (MAPK) pathways (ERK1/2, p38, and JNK/SAPK) are upstream regulators of the nuclear receptor superfamily (NRSF). These ligand-activated transcription factors are divided into subclasses comprising receptors for endocrine hormones, metabolic compounds (e.g., vitamins, diet), xenobiotics, and mediators released from host immune reactions such as tissue injury and inflammation. These internal and external cues place the NRSF at the frontline as sensors and translators of information from the environment towards the genome. For most of the former "orphan" receptors, physiological and synthetic ligands have been identified, opening intriguing opportunities for combination therapies with existing cancer medications. Hitherto, only preclinical data are available, warranting further validation in clinical trials in patients. The current review summarized the existing literature covering the expression and function of NRSF subclasses in human solid tumors and hematopoietic malignancies and their modulatory effects on innate (e.g., macrophages, dendritic cells) and adaptive (i.e., T cell subsets) immune cells, encouraging mechanistic and pharmacological studies in combination with current clinically approved therapeutics against immune checkpoint molecules (e.g., PD1).

Lipid metabolic reprogramming in tumor microenvironment: from mechanisms to therapeutics

Lipid metabolic reprogramming is an emerging hallmark of cancer. In order to sustain uncontrolled proliferation and survive in unfavorable environments that lack oxygen and nutrients, tumor cells undergo metabolic transformations to exploit various ways of acquiring lipid and increasing lipid oxidation. In addition, stromal cells and immune cells in the tumor microenvironment also undergo lipid metabolic reprogramming, which further affects tumor functional phenotypes and immune responses. Given that lipid metabolism plays a critical role in supporting cancer progression and remodeling the tumor microenvironment, targeting the lipid metabolism pathway could provide a novel approach to cancer treatment. This review seeks to: (1) clarify the overall landscape and mechanisms of lipid metabolic reprogramming in cancer, (2) summarize the lipid metabolic landscapes within stromal cells and immune cells in the tumor microenvironment, and clarify their roles in tumor progression, and (3) summarize potential therapeutic targets for lipid metabolism, and highlight the potential for combining such approaches with other anti-tumor therapies to provide new therapeutic opportunities for cancer patients.

Decoding the crosstalk between mevalonate metabolism and T cell function

The mevalonate pathway is an essential metabolic pathway in T cells regulating development, proliferation, survival, differentiation, and effector functions. The mevalonate pathway is a complex, branched pathway composed of many enzymes that ultimately generate cholesterol and nonsterol isoprenoids. T cells must tightly control metabolic flux through the branches of the mevalonate pathway to ensure sufficient isoprenoids and cholesterol are available to meet cellular demands. Unbalanced metabolite flux through the sterol or the nonsterol isoprenoid branch is metabolically inefficient and can have deleterious consequences for T cell fate and function. Accordingly, there is tight regulatory control over metabolic flux through the branches of this essential lipid synthetic pathway. In this review we provide an overview of how the branches of the mevalonate pathway are regulated in T cells and discuss our current understanding of the relationship between mevalonate metabolism, cholesterol homeostasis and T cell function.

Unveiling tumor immune evasion mechanisms: abnormal expression of transporters on immune cells in the tumor microenvironment

The tumor microenvironment (TME) is a crucial driving factor for tumor progression and it can hinder the body's immune response by altering the metabolic activity of immune cells. Both tumor and immune cells maintain their proliferative characteristics and physiological functions through transporter-mediated regulation of nutrient acquisition and metabolite efflux. Transporters also play an important role in modulating immune responses in the TME. In this review, we outline the metabolic characteristics of the TME and systematically elaborate on the effects of abundant metabolites on immune cell function and transporter expression. We also discuss the mechanism of tumor immune escape due to transporter dysfunction. Finally, we introduce some transporter-targeted antitumor therapeutic strategies, with the aim of providing new insights into the development of antitumor drugs and rational drug usage for clinical cancer therapy.

Regulatory mechanism underlying liver X receptor effects on the tumor microenvironment, inflammation and tumorigenesis

INTRODUCTION

Liver X receptors (LXRs) have emerged as novel targets for tumor treatment. LXRs within the tumor microenvironment show the capacity to impact tumorigenesis and tumor development by regulating the infiltration of immune cells and release of cytokines to moderate inflammation.

AREAS COVERED

In this review, we present a systematic description of recent progress in understanding the impact of LXRs on the tumor microenvironment and tumorigenesis. We also summarize the antitumor effects mediated by LXRs via their regulation of cytokine expression. Additionally, we discuss the limitations of LXR research in tumor studies to date.

EXPERT OPINION

Previous studies have demonstrated abnormal LXR expression in tumor tissues, and activation of LXRs has been shown to inhibit tumorigenesis and promote apoptosis in tumor cells. However, LXRs can also affect tumorigenesis by regulating immune cell functions within the tumor immune microenvironment. By summarizing the impact of LXRs on immune cells, we provide new insights into the multifaceted nature of LXRs as antitumor targets.

Lipid metabolism reprogramming of CD8+ T cell and therapeutic implications in cancer

Effector, memory and exhaustion are three phenotypes of CD8⁺ T cell. In tumor microenvironment (TME), metabolism dysfunction of the three should take the blame for immune escape. Against background of CD8⁺ T cell in normal development, multiple determinants in TME, including nutrition competition, PD-1 signals and other cancer- CD8⁺ T cell interaction, cause metabolism reprograming, including failure in energy metabolism and other abnormal lipid metabolism. Further, incompatibility of different CD8⁺ T cell metabolism pattern results in unresponsiveness of immune checkpoint blockade (ICB). Therefore, combination of ICB and drugs aiming at abnormal lipid metabolism provides promising direction to improve cancer therapy.

The Dichotomy of Interleukin-9 Function in the Tumor Microenvironment

Interleukin 9 (IL-9) is a cytokine with potent proinflammatory properties that plays a central role in pathologies such as allergic asthma, immunity to parasitic infection, and autoimmunity. More recently, IL-9 has garnered considerable attention in tumor immunity. Historically, IL-9 has been associated with a protumor function in hematological malignancies and an antitumor function in solid malignancies. However, recent discoveries of the dynamic role of IL-9 in cancer progression suggest that IL-9 can act as both a pro- or antitumor factor in various hematological and solid malignancies. This review summarizes IL-9-dependent control of tumor growth, regulation, and therapeutic applicability of IL-9 blockade and IL-9-producing cells in cancer.

Spatially resolved multi-omics highlights cell-specific metabolic remodeling and interactions in gastric cancer

Mapping tumor metabolic remodeling and their spatial crosstalk with surrounding non-tumor cells can fundamentally improve our understanding of tumor biology, facilitates the designing of advanced therapeutic strategies. Here, we present an integration of mass spectrometry imaging-based spatial metabolomics and lipidomics with microarray-based spatial transcriptomics to hierarchically visualize the intratumor metabolic heterogeneity and cell metabolic interactions in same gastric cancer sample. Tumor-associated metabolic reprogramming is imaged at metabolic-transcriptional levels, and maker metabolites, lipids, genes are connected in metabolic pathways and colocalized in the heterogeneous cancer tissues. Integrated data from spatial multi-omics approaches coherently identify cell types and distributions within the complex tumor microenvironment, and an immune cell-dominated "tumor-normal interface" region where tumor cells contact adjacent tissues are characterized with distinct transcriptional signatures and significant immunometabolic alterations. Our approach for mapping tissue molecular architecture provides highly integrated picture of intratumor heterogeneity, and transform the understanding of cancer metabolism at systemic level.

Myeloid-derived suppressor cells deficient in cholesterol biosynthesis promote tumor immune evasion

Cancer immunotherapy targeting myeloid-derived suppressor cells (MDSCs) is one of the most promising anticancer strategies. Metabolic reprogramming is vital for MDSC activation, however, the regulatory mechanisms of cholesterol metabolic reprogramming in MDSCs remains largely unexplored. Using the receptor-interacting protein kinase 3 (RIPK3)-deficient MDSC model, a previously established tumor-infiltrating MDSC-like model, we found that the cholesterol accumulation was significantly decreased in these cells. Moreover, the phosphorylated AKT-mTORC1 signaling was reduced, and downstream SREBP2-HMGCR-mediated cholesterol synthesis was blunted. Interestingly, cholesterol deficiency profoundly elevated the immunosuppressive activity of MDSCs. Mechanistically, cholesterol elimination induced nuclear accumulation of LXRβ, thereby promoting LXRβ-RXRα heterodimer binding of a novel composite element in the promoter of Arg1. Furthermore, itraconazole enhanced the immunosuppressive activity of MDSCs to boost tumor growth by suppressing the RIPK3-AKT-mTORC1 pathway and impeding cholesterol synthesis. Our findings demonstrate that RIPK3 deficiency leads to cholesterol abrogation in MDSCs, which facilitates tumor-infiltrating MDSC activation, and highlight the therapeutic potential of targeting cholesterol synthesis to overcome tumor immune evasion.

Anticancer Activity of Methyl Protodioscin against Prostate Cancer by Modulation of Cholesterol-Associated MAPK Signaling Pathway <i>via</i> FOXO1 Induction

Methyl protodioscin (MPD), a furostanol saponin found in the rhizomes of Dioscoreaceae, has lipid-lowering and broad anticancer properties. However, the efficacy of MPD in treating prostate cancer remains unexplored. Therefore, the present study aimed to evaluate the anticancer activity and action mechanism of MPD in prostate cancer. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), wound healing, transwell, and flow cytometer assays revealed that MPD suppressed proliferation, migration, cell cycle, and invasion and induced apoptosis of DU145 cells. Mechanistically, MPD decreased cholesterol concentration in the cholesterol oxidase, peroxidase and 4-aminoantipyrine phenol (COD-PAP) assay, disrupting the lipid rafts as detected using immunofluorescence and immunoblot analyses after sucrose density gradient centrifugation. Further, it reduced the associated mitogen-activated protein kinase (MAPK) signaling pathway protein P-extracellular regulated protein kinase (ERK), detected using immunoblot analysis. Forkhead box O (FOXO)1, a tumor suppressor and critical factor controlling cholesterol metabolism, was predicted to be a direct target of MPD and induced by MPD. Notably, in vivo studies demonstrated that MPD significantly reduced tumor size, suppressed cholesterol concentration and the MAPK signaling pathway, and induced FOXO1 expression and apoptosis in tumor tissue in a subcutaneous mouse model. These results suggest that MPD displays anti-prostate cancer activity by inducing FOXO1 protein, reducing cholesterol concentration, and disrupting lipid rafts. Consequently, the reduced MAPK signaling pathway suppresses proliferation, migration, invasion, and cell cycle and induces apoptosis of prostate cancer cells.

Cholesterol suppresses human iTreg differentiation and nTreg function through mitochondria-related mechanisms

BACKGROUND

Both the crystalline and soluble forms of cholesterol increase macrophage secretion of interleukin 1β (IL-1β), aggravating the inflammatory response in atherosclerosis (AS). However, the link between cholesterol and regulatory T cells (Tregs) remains unclear. This study aimed to investigate the effect of cholesterol treatment on Tregs.

METHODS

Differentiation of induced Tregs (iTregs) was analyzed using flow cytometry. The expression of hypoxia-inducible factor-1a (HIF-1a) and its target genes was measured by western blotting and/or RT-qPCR. Two reporter jurkat cell lines were constructed by lentiviral transfection. Mitochondrial function and the structure of natural Tregs (nTregs) were determined by tetramethylrhodamine (TMRM) and mitoSOX staining, Seahorse assay, and electron microscopy. The immunoregulatory function of nTregs was determined by nTreg-macrophage co-culture assay and ELISA.

RESULTS

Cholesterol treatment suppressed iTreg differentiation and impaired nTreg function. Mechanistically, cholesterol induced the production of mitochondrial reactive oxygen species (mtROS) in naïve T cells, inhibiting the degradation of HIF-1α and unleashing its inhibitory effects on iTreg differentiation. Furthermore, cholesterol-induced mitochondrial oxidative damage impaired the immunosuppressive function of nTregs. Mixed lymphocyte reaction and nTreg-macrophage co-culture assays revealed that cholesterol treatment compromised the ability of nTregs to inhibit pro-inflammatory conventional T cell proliferation and promote the anti-inflammatory functions of macrophages. Finally, mitoTEMPO (MT), a specific mtROS scavenger, restored iTreg differentiation and protected nTreg from further deterioration.

CONCLUSION

Our findings suggest that cholesterol may aggravate inflammation within AS plaques by acting on both iTregs and nTregs, and that MT may be a promising anti-atherogenic drug.

Statin drugs enhance responses to immune checkpoint blockade in head and neck cancer models

BACKGROUND

Anti-PD-1 immune checkpoint blockade is approved for first-line treatment of recurrent/metastatic head and neck squamous cell carcinoma (HNSCC), but few patients respond. Statin drugs (HMG-CoA reductase inhibitors) are associated with superior survival in several cancer types, including HNSCC. Emerging data suggest that manipulation of cholesterol may enhance some aspects of antitumor immunity.

METHODS

We used syngeneic murine models (mouse oral cancer, MOC1 and TC-1) to investigate our hypothesis that a subset of statin drugs would enhance antitumor immunity and delay tumor growth.

RESULTS

Using an ex vivo coculture assay of murine cancer cells and tumor infiltrating lymphocytes, we discovered that all seven statin drugs inhibited tumor cell proliferation. Simvastatin and lovastatin also enhanced T-cell killing of tumor cells. In mice, daily oral simvastatin or lovastatin enhanced tumor control and extended survival when combined with PD-1 blockade, with rejection of MOC1 tumors in 30% of mice treated with lovastatin plus anti-PD-1. Results from flow cytometry of tumors and tumor-draining lymph nodes suggested T cell activation and shifts from M2 to M1 macrophage predominance as potential mechanisms of combination therapy.

CONCLUSIONS

These results suggest that statins deserve further study as well-tolerated, inexpensive drugs that may enhance responses to PD-1 checkpoint blockade and other immunotherapies for HNSCC.

Cancer cell-intrinsic XBP1 drives immunosuppressive reprogramming of intratumoral myeloid cells by promoting cholesterol production

A hostile microenvironment in tumor tissues disrupts endoplasmic reticulum homeostasis and induces the unfolded protein response (UPR). A chronic UPR in both cancer cells and tumor-infiltrating leukocytes could facilitate the evasion of immune surveillance. However, how the UPR in cancer cells cripples the anti-tumor immune response is unclear. Here, we demonstrate that, in cancer cells, the UPR component X-box binding protein 1 (XBP1) favors the synthesis and secretion of cholesterol, which activates myeloid-derived suppressor cells (MDSCs) and causes immunosuppression. Cholesterol is delivered in the form of small extracellular vesicles and internalized by MDSCs through macropinocytosis. Genetic or pharmacological depletion of XBP1 or reducing the tumor cholesterol content remarkably decreases MDSC abundance and triggers robust anti-tumor responses. Thus, our data unravel the cell-non-autonomous role of XBP1/cholesterol signaling in the regulation of tumor growth and suggest its inhibition as a useful strategy for improving the efficacy of cancer immunotherapy.

Lipid metabolism in tumor-infiltrating T cells: mechanisms and applications

As an essential part of adaptive immunity, T cells coordinate the immune responses against pathogens and cancer cells. Lipid metabolism has emerged as a key regulator for the activation, differentiation, and effector functions of T cells. Therefore, uncovering the molecular mechanisms by which lipid metabolism dictates T cell biology is of vital importance. The tumor microenvironment is a hostile milieu, i.e. often characterized by nutrient restriction. In this environment, various cells, such as T cells and cancer cells, reprogram their metabolism, including their lipid metabolism, to meet their energy and functional needs. Here, we review the participation of fatty acid and cholesterol metabolism homeostasis in orchestrating T cell biology. We demonstrate how the tumor microenvironment reshapes the lipid metabolism in T cells. Importantly, we highlight the current cancer therapeutic interventions that target fatty acid and cholesterol metabolism of T cells. By offering a holistic understanding of how lipid metabolic adaption by T cells facilitates their immunosurveillance in the tumor microenvironment, we believe this review and the future studies might inspire the next-generation immunotherapies.

PPARα at the crossroad of metabolic-immune regulation in cancer

Rewiring metabolism to sustain cell growth, division, and survival is the most prominent feature of cancer cells. In particular, dysregulated lipid metabolism in cancer has received accumulating interest, since lipid molecules serve as cell membrane structure components, secondary signaling messengers, and energy sources. Given the critical role of immune cells in host defense against cancer, recent studies have revealed that immune cells compete for nutrients with cancer cells in the tumor microenvironment and accordingly develop adaptive metabolic strategies for survival at the expense of compromised immune functions. Among these strategies, lipid metabolism reprogramming toward fatty acid oxidation is closely related to the immunosuppressive phenotype of tumor-infiltrated immune cells, including macrophages and dendritic cells. Therefore, it is important to understand the lipid-mediated crosstalk between cancer cells and immune cells in the tumor microenvironment. Peroxisome proliferator-activated receptors (PPARs) consist of a nuclear receptor family for lipid sensing, and one of the family members PPARα is responsible for fatty acid oxidation, energy homeostasis, and regulation of immune cell functions. In this review, we discuss the emerging role of PPARα-associated metabolic-immune regulation in tumor-infiltrated immune cells, and key metabolic events and pathways involved, as well as their influences on antitumor immunity.

Lipids for CD8+ TILs: Beneficial or harmful?

Lipids and lipid metabolism play crucial roles in regulating T cell function and are tightly related to the establishment of immune memory. It is reported that tumor-infiltrating CD8+T lymphocytes (CD8+TILs) burn fats to restore their impaired effector function due to the lack of glucose. Conversely, fatty acids (FAs) and cholesterol in the tumor microenvironment (TME) drive the CD8+ TILs dysfunction. The origin of dysfunctional CD8+ TILs shares important features with memory T cell’s precursor, but whether lipids and/or lipid metabolism reprogramming directly influence the memory plasticity of dysfunctional CD8+ TILs remains elusive. It is necessary to understand the interplay between cellular lipid metabolism and dysfunction of CD8+ TILs in the case of targeting T cell’s metabolism to synergize cancer immunotherapy. Therefore, in this review, we summarize the latest research on CD8+ TILs lipid metabolism, evaluate the impacts of lipids in the TME to CD8+ TILs, and highlight the significance of promoting memory phenotype cell formation by targeting CD8+ T cells lipid metabolism to provide longer duration of cancer immunotherapy efficacy.

Reprogramming T-Cell Metabolism for Better Anti-Tumor Immunity

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

Targeting lipid metabolism reprogramming of immunocytes in response to the tumor microenvironment stressor: A potential approach for tumor therapy

The tumor microenvironment (TME) has become a major research focus in recent years. The TME differs from the normal extracellular environment in parameters such as nutrient supply, pH value, oxygen content, and metabolite abundance. Such changes may promote the initiation, growth, invasion, and metastasis of tumor cells, in addition to causing the malfunction of tumor-infiltrating immunocytes. As the neoplasm develops and nutrients become scarce, tumor cells transform their metabolic patterns by reprogramming glucose, lipid, and amino acid metabolism in response to various environmental stressors. Research on carcinoma metabolism reprogramming suggests that like tumor cells, immunocytes also switch their metabolic pathways, named “immunometabolism”, a phenomenon that has drawn increasing attention in the academic community. In this review, we focus on the recent progress in the study of lipid metabolism reprogramming in immunocytes within the TME and highlight the potential target molecules, pathways, and genes implicated. In addition, we discuss hypoxia, one of the vital altered components of the TME that partially contribute to the initiation of abnormal lipid metabolism in immune cells. Finally, we present the current immunotherapies that orchestrate a potent antitumor immune response by mediating the lipid metabolism of immunocytes, highlight the lipid metabolism reprogramming capacity of various immunocytes in the TME, and propose promising new strategies for use in cancer therapy.

Role of Lipids and Lipid Metabolism in Prostate Cancer Progression and the Tumor’s Immune Environment

Modulation of lipid metabolism during cancer development and progression is one of the hallmarks of cancer in solid tumors; its importance in prostate cancer (PCa) has been demonstrated in numerous studies. Lipid metabolism is known to interact with androgen receptor signaling, an established driver of PCa progression and castration resistance. Similarly, immune cell infiltration into prostate tissue has been linked with the development and progression of PCa as well as with disturbances in lipid metabolism. Immuno-oncological drugs inhibit immune checkpoints to activate immune cells’ abilities to recognize and destroy cancer cells. These drugs have proved to be successful in treating some solid tumors, but in PCa their efficacy has been poor, with only a small minority of patients demonstrating a treatment response. In this review, we first describe the importance of lipid metabolism in PCa. Second, we collate current information on how modulation of lipid metabolism of cancer cells and the surrounding immune cells may impact the tumor’s immune responses which, in part, may explain the unimpressive results of immune-oncological treatments in PCa.