Metabolic Controls on Epigenetic Reprogramming in Regulatory T Cells

Regulatory T Cells in Tumor Microenvironment: Therapeutic Approaches and Clinical Implications

Regulatory T cells (Tregs), previously referred to as suppressor T cells, represent a distinct subset of CD4+ T cells that are uniquely specialized for immune suppression. They are characterized by the constitutive expression of the transcription factor FoxP3 in their nuclei, along with CD25 (the IL-2 receptor α-chain) and CTLA-4 on their cell surface. Tregs not only restrict natural killer cell-mediated cytotoxicity but also inhibit the proliferation of CD4+ and CD8+ T-cells and suppress interferon-γ secretion by immune cells, ultimately impairing an effective antitumor immune response. Treg cells are widely recognized as a significant barrier to the effectiveness of tumor immunotherapy in clinical settings. Extensive research has consistently shown that Treg cells play a pivotal role in facilitating tumor initiation and progression. Conversely, the depletion of Treg cells has been linked to a marked delay in tumor growth and development.

Epigenetic modulation by oncolytic viruses: Implications for cancer therapeutic efficacy

Among various therapeutic agents, Oncolytic Viruses (OVs) are the most promising anticancer therapeutics because of their tumor-specific targeting and capability to mediate an antitumor immune response. In this review, we will discuss how epigenetic reprogramming of both the host and tumor can facilitate increased sensitivity of tumors to OV therapy. OVs infect tumor cells and modulate epigenetic landscapes, including DNA methylation, histone modifications, and chromatin remodeling, as well as non-coding RNA expression that consequently induces immune responses. These epigenetic changes, including hypermethylation of tumor-associated antigen genes and chromatin accessibility alterations, enhance the immunogenicity of tumors to facilitate recognition by the immune system. Here, we provide a general review addressing this question by discussing the potential benefits of combining OVs with epigenetic drugs to combat resistance and promote treatment efficacy. This information illustrates the importance of personalized OV therapy regarding epigenome in individual profiles and transitions. Still, it extends difficulty in inducing with acquisitions of viral-induced changes globally and making translatable steps by creating cancer-specific predictive treatment models.

Bridging epigenomics and tumor immunometabolism: molecular mechanisms and therapeutic implications

Epigenomic modifications-such as DNA methylation, histone acetylation, and histone methylation-and their implications in tumorigenesis, progression, and treatment have emerged as a pivotal field in cancer research. Tumors undergo metabolic reprogramming to sustain proliferation and metastasis in nutrient-deficient conditions, while suppressing anti-tumor immunity in the tumor microenvironment (TME). Concurrently, immune cells within the immunosuppressive TME undergo metabolic adaptations, leading to alterations in their immune function. The complicated interplay between metabolites and epigenomic modulation has spotlighted the significance of epigenomic regulation in tumor immunometabolism. In this review, characteristics of the epigenomic modification associated with tumors are systematically summarized alongside with their regulatory roles in tumor metabolic reprogramming and immunometabolism. Classical and emerging approaches are delineated to broaden the boundaries of research on the crosstalk research on the crosstalk between tumor immunometabolism and epigenomics. Furthermore, we discuss potential therapeutic strategies that target tumor immunometabolism to modulate epigenomic modifications, highlighting the burgeoning synergy between metabolic therapies and immunotherapy as a promising avenue for cancer treatment.

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.

Epigenetic regulation of transcription factors involved in NLRP3 inflammasome and NF-kB signaling pathways

The NLRP3 inflammasome and NF-κB signaling pathways play crucial roles in orchestrating inflammation and immune defense.​ This review explores the intricate relationship between these pathways and epigenetic regulation, a field of growing importance in understanding immune responses. Epigenetic modifications, including DNA methylation, histone modifications, and non-coding RNAs (ncRNAs), significantly influence the activity of genes involved in these pathways, thereby modulating inflammatory responses. The review provides a comprehensive overview of current research on how epigenetic mechanisms interact with and regulate the NLRP3 inflammasome and NF-κB signaling pathways. It delves into advanced epigenetic concepts such as RNA modifications and 3D genome organization, and their impact on immune regulation. Furthermore, the implications of these findings for developing novel therapeutic strategies targeting epigenetic regulators in inflammatory diseases are discussed. By synthesizing recent advancements in this rapidly evolving field, this review underscores the critical role of epigenetic regulation in immune signaling and highlights the potential for epigenetic-based therapies in treating a wide range of inflammatory conditions, including autoimmune disorders and cancer.

Modulation of the Neuro-Cancer Connection by Metabolites of Gut Microbiota

The gut-brain-cancer axis represents a novel and intricate connection between the gut microbiota, neurobiology, and cancer progression. Recent advances have accentuated the significant role of gut microbiota metabolites in modulating systemic processes that influence both brain health and tumorigenesis. This paper explores the emerging concept of metabolite-mediated modulation within the gut-brain-cancer connection, focusing on key metabolites such as short-chain fatty acids (SCFAs), tryptophan derivatives, secondary bile acids, and lipopolysaccharides (LPS). While the gut microbiota's impact on immune regulation, neuroinflammation, and tumor development is well established, gaps remain in grasping how specific metabolites contribute to neuro-cancer interactions. We discuss novel metabolites with potential implications for neurobiology and cancer, such as indoles and polyamines, which have yet to be extensively studied. Furthermore, we review preclinical and clinical evidence linking gut dysbiosis, altered metabolite profiles, and brain tumors, showcasing limitations and research gaps, particularly in human longitudinal studies. Case studies investigating microbiota-based interventions, including dietary changes, fecal microbiota transplantation, and probiotics, demonstrate promise but also indicate hurdles in translating these findings to clinical cancer therapies. This paper concludes with a call for standardized multi-omics approaches and bi-directional research frameworks integrating microbiome, neuroscience, and oncology to develop personalized therapeutic strategies for neuro-cancer patients.

Induced regulatory T cells as immunotherapy in allotransplantation and autoimmunity: challenges and opportunities

Regulatory T cells play a crucial role in the homeostasis of the immune response. Regulatory T cells are mainly generated in the thymus and are characterized by the expression of Foxp3, which is considered the regulatory T-cell master transcription factor. In addition, regulatory T cells can be induced from naive CD4+ T cells to express Foxp3 under specific conditions both in vivo (peripheral regulatory T cells) and in vitro (induced regulatory T cells). Both subsets of thymic regulatory T cells and peripheral regulatory T cells are necessary for the establishment of immune tolerance to self and non-self antigens. Although it has been postulated that induced regulatory T cells may be less stable compared to regulatory T cells, mainly due to epigenetic differences, accumulating evidence in animal models shows that induced regulatory T cells are stable in vivo and can be used for the treatment of inflammatory disorders, including autoimmune diseases and allogeneic transplant rejection. In this review, we describe the biological characteristics of induced regulatory T cells, as well as the key factors involved in induced regulatory T-cell transcriptional, metabolic, and epigenetic regulation, and discuss recent advances for de novo generation of stable regulatory T cells and their use as immunotherapeutic tools in different experimental models. Moreover, we discuss the challenges and considerations for the application of induced regulatory T cells in clinical trials and describe the new approaches proposed to achieve in vivo stability, including functional or metabolic reprogramming and epigenetic editing.

Improving regulatory T cell production through mechanosensing

Induced Tregs (iTregs) have great promise in adoptive immunotherapy for treatment of autoimmune diseases. This report investigates the impacts of substrate stiffness on human Treg induction, providing a powerful yet simple approach to improving production of these cells. Conventional CD4+ human T cells were activated on materials of different elastic modulus and cultured under suppressive conditions. Enhanced Treg induction was observed on softer materials as early as 3 days following activation and persisted for multiple weeks. Substrate stiffness also affected epigenetic modification of Treg specific genes and Treg suppressive capacity. Tregs induced on substrates of an optimal stiffness balance quantity and suppressive quality.

The Role of Regulatory T Cells in Allergic Diseases: Collegium Internationale Allergologicum (CIA) Update 2024

BACKGROUND

Allergy represents a major health problem of increasing prevalence worldwide with a high socioeconomic impact. Our knowledge on the molecular mechanisms underlying allergic diseases and their treatments has significantly improved over the last years. The generation of allergen-specific regulatory T cells (Tregs) is crucial in the induction of healthy immune responses to allergens, preventing the development and worsening of allergic diseases.

SUMMARY

In the last decades, intensive research has focused on the study of the molecular mechanisms involved in Treg development and Treg-mediated suppression. These mechanisms are essential for the induction of sustained tolerance by allergen-specific immunotherapy (AIT) after treatment discontinuation. Compelling experimental evidence demonstrated altered suppressive capacity of Tregs in patients suffering from allergic rhinitis, allergic asthma, food allergy, or atopic dermatitis, as well as the restoration of their numbers and functionality after successful AIT.

KEY MESSAGE

The better understanding of the molecular mechanisms involved in Treg generation during allergen tolerance induction might well contribute to the development of novel strategies for the prevention and treatment of allergic diseases.

Modulating Treg stability to improve cancer immunotherapy

Immunosuppressive regulatory T cells (Tregs) provide a main mechanism of tumor immune evasion. Targeting Tregs, especially in the tumor microenvironment (TME), continues to be investigated to improve cancer immunotherapy. Recent studies have unveiled intratumoral Treg heterogeneity and plasticity, furthering the complexity of the role of Tregs in tumor immunity and immunotherapy response. The phenotypic and functional diversity of intratumoral Tregs can impact their response to therapy and may offer new targets to modulate specific Treg subsets. In this review we provide a unifying framework of critical factors contributing to Treg heterogeneity and plasticity in the TME, and we discuss how this information can guide the development of more specific Treg-targeting therapies for cancer immunotherapy.

Zfp335 establishes eTreg lineage and neonatal immune tolerance by targeting Hadha-mediated fatty acid oxidation

Regulatory T cells (Tregs) are instrumental in maintaining immune tolerance and preventing destructive autoimmunity, but how heterogeneous Treg populations are established remains largely unknown. Here, we show that Zfp335 deletion in Tregs failed to differentiate into effector Tregs (eTregs) and lose Treg-suppressive function and that KO mice exhibited early-onset lethal autoimmune inflammation with unrestricted activation of conventional T cells. Single-cell RNA-Seq analyses revealed that Zfp335-deficient Tregs lacked a eTreg population and showed dramatic accumulation of a dysfunctional Treg subset. Mechanistically, Zfp335-deficient Tregs displayed reduced oxidative phosphorylation and dysfunctional mitochondrial activity. Further studies revealed that Zfp335 controlled eTreg differentiation by regulating fatty acid oxidation (FAO) through direct targeting of the FAO enzyme Hadha. Importantly, we demonstrate a positive correlation between ZNF335 and HADHA expression in human eTregs. Our findings reveal that Zfp335 controls FAO-driven eTreg differentiation to establish immune tolerance.

Single-cell profiling reveals inflammatory polarization of human carotid versus femoral plaque leukocytes

Femoral atherosclerotic plaques are less inflammatory than carotid plaques histologically, but limited cell-level data exist regarding comparative immune landscapes and polarization at these sites. We investigated intraplaque leukocyte phenotypes and transcriptional polarization in 49 patients undergoing femoral (n = 23) or carotid (n = 26) endarterectomy using single-cell RNA-Seq (scRNA-Seq; n = 13), flow cytometry (n = 24), and IHC (n = 12). Comparative scRNA-Seq of CD45+-selected leukocytes from femoral (n = 9; 35,265 cells) and carotid (n = 4; 30,655 cells) plaque revealed distinct transcriptional profiles. Inflammatory foam cell-like macrophages and monocytes comprised higher proportions of myeloid cells in carotid plaques, whereas noninflammatory foam cell-like macrophages and LYVE1-overexpressing macrophages comprised higher proportions of myeloid cells in femoral plaque (P < 0.001 for all). A significant comparative excess of CCR2+ macrophages in carotid versus plaque was observed by flow cytometry in a separate validation cohort. B cells were more prevalent and exhibited a comparatively antiinflammatory profile in femoral plaque, whereas cytotoxic CD8+ T cells were more prevalent in carotid plaque. In conclusion, human femoral plaques exhibit distinct macrophage phenotypic and transcriptional profiles as well as diminished CD8+ T cell populations compared with human carotid plaques.

Intracellular spatiotemporal metabolism in connection to target engagement

The metabolism in eukaryotic cells is a highly ordered system involving various cellular compartments, which fluctuates based on physiological rhythms. Organelles, as the smallest independent sub-cell unit, are important contributors to cell metabolism and drug metabolism, collectively designated intracellular metabolism. However, disruption of intracellular spatiotemporal metabolism can lead to disease development and progression, as well as drug treatment interference. In this review, we systematically discuss spatiotemporal metabolism in cells and cell subpopulations. In particular, we focused on metabolism compartmentalization and physiological rhythms, including the variation and regulation of metabolic enzymes, metabolic pathways, and metabolites. Additionally, the intricate relationship among intracellular spatiotemporal metabolism, metabolism-related diseases, and drug therapy/toxicity has been discussed. Finally, approaches and strategies for intracellular spatiotemporal metabolism analysis and potential target identification are introduced, along with examples of potential new drug design based on this.

T cell exhaustion in malignant gliomas

Despite advances in understanding tumor biology, malignant gliomas remain incurable. While immunotherapy has improved outcomes in other cancer types, comparable efficacy has not yet been demonstrated for primary cancers of the central nervous system (CNS). T cell exhaustion, defined as a progressive decrease in effector function, sustained expression of inhibitory receptors, metabolic dysfunction, and distinct epigenetic and transcriptional alterations, contributes to the failure of immunotherapy in the CNS. Herein, we describe recent advances in understanding the drivers of T cell exhaustion in the glioma microenvironment. We discuss the extrinsic and intrinsic factors that contribute to exhaustion and highlight potential avenues for reversing this phenotype. Our ability to directly target specific immunosuppressive drivers in brain cancers would be a major advance in immunotherapy.

Dexmedetomidine alleviates acute lung injury by promoting Tregs differentiation via activation of AMPK/SIRT1 pathway

OBJECTIVES

To explore the anti-inflammatory effect and the potential mechanism of dexmedetomidine in ARDS/ALI.

MATERIALS AND METHODS

C57BL/6 mice and EL-4 cells were used in this research. The ALI model was established by CLP. The level of inflammatory cytokines in the lung and blood, the severity of lung injury, the expression of Foxp3, and the proportion of Tregs were detected before and after dexmedetomidine treatment. The expression of the AMPK/SIRT1 after dexmedetomidine treatment was detected in vivo and in vitro. After blocking the AMPK/SIRT1 pathway or depleting Tregs in vivo, the level of the inflammatory response, tissue injury, and Tregs differentiation were detected again to clarify the effect of dexmedetomidine.

RESULTS

Dexmedetomidine significantly reduced systemic inflammation and lung injury in CLP mice. Dexmedetomidine enhanced the Foxp3 expression in the lungs and the frequency of Tregs in the spleen. Dexmedetomidine up-regulated the protein expression of p-AMPK and SIRT1 in lungs and EL-4 cells and facilitated the differentiation of naïve CD4⁺ T cells into Tregs in vitro. Meanwhile, DEX also increased the expression of Helios in Treg cells.

CONCLUSIONS

DEX could improve ARDS/ALI by facilitating the differentiation of Tregs from naïve CD4⁺ T cells via activating the AMPK/SIRT1 pathway.

The novel sustained 3-hydroxybutyrate donor poly-D-3-hydroxybutyric acid prevents inflammatory bowel disease through upregulation of regulatory T-cells

Inflammatory bowel disease (IBD) is a chronic persistent intestinal disorder, with ulcerative colitis and Crohn's disease being the most common. However, the physio-pathological development of IBD is still unknown. Therefore, research on the etiology and treatment of IBD has been conducted using a variety of approaches. Short-chain fatty acids such as 3-hydroxybutyrate (3-HB) are known to have various physiological activities. In particular, the production of 3-HB by the intestinal microflora is associated with the suppression of various inflammatory diseases. In this study, we investigated whether poly-D-3-hydroxybutyric acid (PHB), a polyester of 3-HB, is degraded by intestinal microbiota and works as a slow-release agent of 3-HB. Further, we examined whether PHB suppresses the pathogenesis of IBD models. As long as a PHB diet increased 3-HB concentrations in the feces and blood, PHB suppressed weight loss and histological inflammation in a dextran sulfate sodium-induced IBD model. Furthermore, PHB increased the accumulation of regulatory T cells in the rectum without affecting T cells in the spleen. These results indicate that PHB has potential applications in treating diseases related to the intestinal microbiota as a sustained 3-HB donor. We show for the first time that biodegradable polyester exhibits intestinal bacteria-mediated bioactivity toward IBD. The use of bioplastics, which are essential materials for sustainable social development, represents a novel approach to diseases related to dysbiosis, including IBD.