Metabolic programs of T cell tissue residency empower tumour immunity

CIMT 2024: Report on the 21st Annual Meeting of the Association for Cancer Immunotherapy

The 21st Association for Cancer Immunotherapy (CIMT) Annual Meeting took place from May 15th to May 17th in Mainz, Germany, and was attended by a total of 855 academic and clinical professionals hailing from 33 different countries. The conference served as a platform for these experts to convene and discuss the latest breakthroughs in cancer immunology and immunotherapy research. Dedicated sessions covering advancements in artificial intelligence tools for cancer immunotherapy research, as well as the landscape of cancer care and cancer immunotherapy trials on the African continent, prompted lively and informative discussions among the attendees. This report aims to provide an overview of the most noteworthy highlights and key takeaways from CIMT2024.

Emerging biochemical, microbial and immunological evidence in the search for why HLA-B∗27 confers risk for spondyloarthritis

The strong association of the human leukocyte antigen B∗27 alleles (HLA-B∗27) with spondyloarthritis and related rheumatic conditions has long fascinated researchers, yet the precise mechanisms underlying its pathogenicity remain elusive. Here, we review how interplay between the microbiome, the immune system, and the enigmatic HLA-B∗27 could trigger spondyloarthritis, with a focus on whether HLA-B∗27 presents an arthritogenic peptide. We propose mechanisms by which the unique biochemical characteristics of the HLA-B∗27 protein structure, particularly its peptide binding groove, could dictate its propensity to induce pathological T cell responses. We further provide new insights into how TRBV9+ CD8+ T cells are implicated in the disease process, as well as how the immunometabolism of T cells modulates tissue-specific inflammatory responses in spondyloarthritis. Finally, we present testable models and suggest approaches to this problem in future studies given recent advances in computational biology, chemical biology, structural biology, and small-molecule therapeutics.

Resident memory T cells and cancer

Tissue-resident memory T (TRM) cells positively correlate with cancer survival, but the anti-tumor mechanisms underlying this relationship are not understood. This review reconciles these observations, summarizing concepts of T cell immunosurveillance, fundamental TRM cell biology, and clinical observations on the role of TRM cells in cancer and immunotherapy outcomes. We also discuss emerging strategies that utilize TRM-phenotype cells for patient diagnostics, staging, and therapy. Current challenges are highlighted, including a lack of standardized T cell nomenclature and our limited understanding of relationships between T cell markers and underlying tumor biology. Existing findings are integrated into a summary of the field while emphasizing opportunities for future research.

3D chromatin-based variant-to-gene maps across 57 human cell types reveal the cellular and genetic architecture of autoimmune disease susceptibility

A portion of the genetic basis for many common autoimmune disorders has been uncovered by genome-wide association studies (GWAS), but GWAS do not reveal causal variants, effector genes, or the cell types impacted by disease-associated variation. We have generated 3D genomic datasets consisting of promoter-focused Capture-C, Hi-C, ATAC-seq, and RNA-seq and integrated these data with GWAS of 16 autoimmune traits to physically map disease-associated variants to the effector genes they likely regulate in 57 human cell types. These 3D maps of gene cis-regulatory architecture are highly powered to identify the cell types most likely impacted by disease-associated genetic variation compared to 1D genomic features, and tend to implicate different effector genes than eQTL approaches in the same cell types. Most of the variants implicated by these cis-regulatory architectures are highly trait-specific, but nearly half of the target genes connected to these variants are shared across multiple autoimmune disorders in multiple cell types, suggesting a high level of genetic diversity and complexity among autoimmune diseases that nonetheless converge at the level of target gene and cell type. Substantial effector gene sharing led to the common enrichment of similar biological networks across disease and cell types. However, trait-specific pathways representing potential areas for disease-specific intervention were identified. To test this, we pharmacologically validated squalene synthase, a cholesterol biosynthetic enzyme encoded by the FDFT1 gene implicated by our approach in MS and SLE, as a novel immunomodulatory drug target controlling inflammatory cytokine production by human T cells. These data represent a comprehensive resource for basic discovery of gene cis-regulatory mechanisms, and the analyses reported reveal mechanisms by which autoimmune-associated variants act to regulate gene expression, function, and pathology across multiple, distinct tissues and cell types.

Crosstalk between Regnase-1 and -3 shapes mast cell survival and cytokine expression

Post-transcriptional regulation of immune-related transcripts by RNA-binding proteins (RBPs) impacts immune cell responses, including mast cell functionality. Despite their importance in immune regulation, the functional role of most RBPs remains to be understood. By manipulating the expression of specific RBPs in murine mast cells, coupled with mass spectrometry and transcriptomic analyses, we found that the Regnase family of proteins acts as a potent regulator of mast cell physiology. Specifically, Regnase-1 is required to maintain basic cell proliferation and survival, whereas both Regnase-1 and -3 cooperatively regulate the expression of inflammatory transcripts upon activation, with Tnf being a primary target in both human and mouse cells. Furthermore, Regnase-3 directly interacts with Regnase-1 in mast cells and is necessary to restrain Regnase-1 expression through the destabilization of its transcript. Overall, our study identifies protein interactors of endogenously expressed Regnase factors, characterizes the regulatory interplay between Regnase family members in mast cells, and establishes their role in the control of mast cell homeostasis and inflammatory responses.

Lysine lactylation in the regulation of tumor biology

Lysine lactylation (Kla), a newly discovered post-translational modification (PTM) of lysine residues, is progressively revealing its crucial role in tumor biology. A growing body of evidence supports its capacity of transcriptional regulation through histone modification and modulation of non-histone protein function. It intricately participates in a myriad of events in the tumor microenvironment (TME) by orchestrating the transitions of immune states and augmenting tumor malignancy. Its preferential modification of metabolic proteins underscores its specific regulatory influence on metabolism. This review focuses on the effect and the probable mechanisms of Kla-mediated regulation of tumor metabolism, the upstream factors that determine Kla intensity, and its potential implications for the clinical diagnosis and treatment of tumors.

Tissue-resident memory T cells in immunotherapy and immune-related adverse events by immune checkpoint inhibitor

Tissue-resident memory T cells (TRM) are a specialized subset of T cells that reside in tissues and provide long-term protective immunity against pathogens that enter the body through that specific tissue. TRM cells have specific phenotype and reside preferentially in barrier tissues. Recent studies have revealed that TRM cells are the main target of immune checkpoint inhibitor immunotherapy since their role in cancer immunosurveillance. Furthermore, TRM cells also play a crucial part in pathogenesis of immune-related adverse events (irAEs). Here, we provide a concise review of biological characteristics of TRM cells, and the major advances and recent findings regarding their involvement in immune checkpoint inhibitor immunotherapy and the corresponding irAEs.

Tissue-resident memory CD103+CD8+ T cells in colorectal cancer: its implication as a prognostic and predictive liver metastasis biomarker

BACKGROUND

Tissue-resident memory CD103+CD8+ T cells (CD103+CD8+ TRMs) are important components of anti-tumor immunity. However, the significance of CD103+CD8+ TRMs in colorectal cancer (CRC) and their advantages remain unclear.

METHODS

Clinical data and specimens were used to evaluate the significance of CD103+CD8+ TRMs in CRC. A mouse subcutaneous tumorigenesis model and colony-formation assay were conducted to evaluate the anti-tumor effects of CD103+CD8+ TRMs. Finally, the infiltration density and function of CD103+CD8+ TRMs in the tumors were evaluated using flow cytometry.

RESULTS

In this study, we showed that highly infiltrated CD103+CD8+ TRMs were associated with earlier clinical stage and negative VEGF expression in CRC patients and predicted a favorable prognosis for CRC/CRC liver metastases patients. Interestingly, we also found that CD103+CD8+ TRMs may have predictive potential for whether CRC develops liver metastasis in CRC. In addition, we found a positive correlation between the ratio of the number of α-SMA+ vessels to the sum of the number of α-SMA+ and CD31+ vessels in CRC, and the infiltration level of CD103+CD8+ TRMs. In addition, anti-angiogenic therapy promoted infiltration of CD103+CD8+ TRMs and enhanced their ability to secrete interferon (IFN)-γ, thus further improving the anti-tumor effect. Moreover, in vivo experiments showed that compared with peripheral blood CD8+ T cells, CD103+CD8+ TRMs infused back into the body could also further promote CD8+ T cells to infiltrate the tumor, and they had a stronger ability to secrete IFN-γ, which resulted in better anti-tumor effects.

CONCLUSION

We demonstrated that CD103+CD8+ TRMs have the potential for clinical applications and provide new ideas for combined anti-tumor therapeutic strategies, such as anti-tumor angiogenesis therapy and CAR-T combined immunotherapy.

Targeting metabolic pathways to counter cancer immunotherapy resistance

Immunotherapies have revolutionized the treatment of certain cancers, but challenges remain in overcoming immunotherapy resistance. Research shows that metabolic modulation of the tumor microenvironment can enhance antitumor immunity. Here, we discuss recent preclinical and clinical evidence for the efficacy of combining metabolic modifiers with immunotherapies. While this combination holds great promise, a few key areas must be addressed, which include identifying the effects of metabolic modifiers on immune cell metabolism, the putative biomarkers of therapeutic efficacy, the efficacy of modifiers on tumors harboring metabolic heterogeneity, and the potential development of resistance due to tumor reliance on alternative metabolic pathways. We propose solutions to these problems and posit that assessing these parameters is crucial for considering the potential of metabolic modifiers in sensitizing tumors to immunotherapies.

Altered cancer metabolism and implications for next-generation CAR T-cell therapies

This review critically examines the evolving landscape of chimeric antigen receptor (CAR) T-cell therapy in treating solid tumors, with a particular focus on the metabolic challenges within the tumor microenvironment. CAR T-cell therapy has demonstrated remarkable success in hematologic malignancies, yet its efficacy in solid tumors remains limited. A significant barrier is the hostile milieu of the tumor microenvironment, which impairs CAR T-cell survival and function. This review delves into the metabolic adaptations of cancer cells and their impact on immune cells, highlighting the competition for nutrients and the accumulation of immunosuppressive metabolites. It also explores emerging strategies to enhance CAR T-cell metabolic fitness and persistence, including genetic engineering and metabolic reprogramming. An integrated approach, combining metabolic interventions with CAR T-cell therapy, has the potential to overcome these constraints and improve therapeutic outcomes in solid tumors.

A Bioactive Injectable Hydrogel Regulates Tumor Metastasis and Wound Healing for Melanoma via NIR-Light Triggered Hyperthermia

Surgical resection remains the mainstream treatment for malignant melanoma. However, challenges in wound healing and residual tumor metastasis pose significant hurdles, resulting in high recurrence rates in patients. Herein, a bioactive injectable hydrogel (BG-Mngel) formed by crosslinking sodium alginate (SA) with manganese-doped bioactive glass (BG-Mn) is developed as a versatile platform for anti-tumor immunotherapy and postoperative wound healing for melanoma. The incorporation of Mn2+ within bioactive glass (BG) can activate the cGAS-STING immune pathway to elicit robust immune response for cancer immunotherapy. Furthermore, doping Mn2+ in BG endows system with excellent photothermal properties, hence facilitating STING activation and reversing the tumor immune-suppressive microenvironment. BG exhibits favorable angiogenic capacity and tissue regenerative potential, and Mn2+ promotes cell migration in vitro. When combining BG-Mngel with anti-PD-1 antibody (α-PD-1) for the treatment of malignant melanoma, it shows enhanced anti-tumor immune response and long-term immune memory response. Remarkably, BG-Mngel can upregulate the expression of genes related to blood vessel formation and promote skin tissue regeneration when treating full-thickness wounds. Overall, BG-MnGel serves as an effective adjuvant therapy to regulate tumor metastasis and wound healing for malignant melanoma.

Epigenetic regulation of tumor immunity

Although cancer has long been considered a genetic disease, increasing evidence shows that epigenetic aberrations play a crucial role in affecting tumor biology and therapeutic response. The dysregulated epigenome in cancer cells reprograms the immune landscape within the tumor microenvironment, thereby hindering antitumor immunity, promoting tumor progression, and inducing immunotherapy resistance. Targeting epigenetically mediated tumor-immune crosstalk is an emerging strategy to inhibit tumor progression and circumvent the limitations of current immunotherapies, including immune checkpoint inhibitors. In this Review, we discuss the mechanisms by which epigenetic aberrations regulate tumor-immune interactions and how epigenetically targeted therapies inhibit tumor progression and synergize with immunotherapy.

Near-Infrared-II Nanomaterials for Activatable Photodiagnosis and Phototherapy

Near-Infrared-II (NIR-II) spans wavelengths between 1,000 to 1,700 nanometers, featuring deep tissue penetration and reduced tissue scattering and absorption characteristics, providing robust support for cancer treatment and tumor imaging research. This review explores the utilization of activatable NIR-II photodiagnosis and phototherapy based on tumor microenvironments (e. g., reactive oxygen species, pH, glutathione, hypoxia) and external stimulation (e. g., laser, ultrasound, photothermal) for precise tumor treatment and imaging. Special emphasis is placed on the advancements and advantages of activatable NIR-II nanomedicines in novel therapeutic modalities like photodynamic therapy, photothermal therapy, and photoacoustic imaging. This encompasses achieving deep tumor penetration, real-time monitoring of the treatment process, and obtaining high-resolution, high signal-to-noise ratio images even at low material concentrations. Lastly, from a clinical perspective, the challenges faced by activatable NIR-II phototherapy are discussed, alongside potential strategies to overcome these hurdles.

A new era of cancer immunotherapy: combining revolutionary technologies for enhanced CAR-M therapy

Significant advancements have been made in the application of chimeric antigen receptor (CAR)-T treatment for blood cancers during the previous ten years. However, its effectiveness in treating solid tumors is still lacking, necessitating the exploration of alternative immunotherapies that can overcome the significant challenges faced by current CAR-T cells. CAR-based immunotherapy against solid tumors shows promise with the emergence of macrophages, which possess robust phagocytic abilities, antigen-presenting functions, and the ability to modify the tumor microenvironment and stimulate adaptive responses. This paper presents a thorough examination of the latest progress in CAR-M therapy, covering both basic scientific studies and clinical trials. This study examines the primary obstacles hindering the realization of the complete potential of CAR-M therapy, as well as the potential strategies that can be employed to overcome these hurdles. With the emergence of revolutionary technologies like in situ genetic modification, synthetic biology techniques, and biomaterial-supported gene transfer, which provide a wider array of resources for manipulating tumor-associated macrophages, we suggest that combining these advanced methods will result in the creation of a new era of CAR-M therapy that demonstrates improved efficacy, safety, and availability.

Metabolic rewiring and communication in cancer immunity

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

CD8+ T cell-based cancer immunotherapy

The immune system in humans is a defense department against both exogenous and endogenous hazards, where CD8+ T cells play a crucial role in opposing pathological threats. Various immunotherapies based on CD8+ T cells have emerged in recent decades, showing their promising results in treating intractable diseases. However, in the fight against the constantly changing and evolving cancers, the formation and function of CD8+ T cells can be challenged by tumors that might train a group of accomplices to resist the T cell killing. As cancer therapy stepped into the era of immunotherapy, understanding the physiological role of CD8+ T cells, studying the machinery of tumor immune escape, and thereby formulating different therapeutic strategies become the imperative missions for clinical and translational researchers to fulfill. After brief basics of CD8+ T cell-based biology is covered, this review delineates the mechanisms of tumor immune escape and discusses different cancer immunotherapy regimens with their own advantages and setbacks, embracing challenges and perspectives in near future.

Homologous-magnetic dual-targeted metal-organic framework to improve the Anti-hepatocellular carcinoma efficacy of PD-1 inhibitor

The insufficient abundance and weak activity of tumour-infiltrating lymphocytes (TILs) are two important reasons for the poor efficacy of PD-1 inhibitors in hepatocellular carcinoma (HCC) treatment. The combined administration of tanshinone IIA (TSA) and astragaloside IV (As) can up-regulate the abundance and activity of TILs by normalising tumour blood vessels and reducing the levels of immunosuppressive factors respectively. For enhancing the efficacy of PD-1 antibody, a magnetic metal-organic framework (MOF) with a homologous tumour cell membrane (Hm) coating (Hm@TSA/As-MOF) is established to co-deliver TSA&As into the HCC microenvironment. Hm@TSA/As-MOF is a spherical nanoparticle and has a high total drug-loading capacity of 16.13 wt%. The Hm coating and magnetic responsiveness of Hm@TSA/As-MOF provide a homologous-magnetic dual-targeting, which enable Hm@TSA/As-MOF to counteract the interference posed by ascites tumour cells and enhance the precision of targeting solid tumours. Hm coating also enable Hm@TSA/As-MOF to evade immune clearance by macrophages. The release of TSA&As from Hm@TSA/As-MOF can be accelerated by HCC microenvironment, thereby up-regulating the abundance and activity of TILs to synergistic PD-1 antibody against HCC. This study presents a nanoplatform to improve the efficacy of PD-1 inhibitors in HCC, providing a novel approach for anti-tumour immunotherapy in clinical practice.

Tissue-resident memory T cells: decoding intra-organ diversity with a gut perspective

Tissue-resident memory T cells (TRM) serve as the frontline of host defense, playing a critical role in protection against invading pathogens. This emphasizes their role in providing rapid on-site immune responses across various organs. The physiological significance of TRM is not just confined to infection control; accumulating evidence has revealed that TRM also determine the pathology of diseases such as autoimmune disorders, inflammatory bowel disease, and cancer. Intensive studies on the origin, mechanisms of formation and maintenance, and physiological significance of TRM have elucidated the transcriptional and functional diversity of these cells, which are often affected by local cues associated with their presence. These were further confirmed by the recent remarkable advancements of next-generation sequencing and single-cell technologies, which allow the transcriptional and phenotypic characterization of each TRM subset induced in different microenvironments. This review first overviews the current knowledge of the cell fate, molecular features, transcriptional and metabolic regulation, and biological importance of TRM in health and disease. Finally, this article presents a variety of recent studies on disease-associated TRM, particularly focusing and elaborating on the TRM in the gut, which constitute the largest and most intricate immune network in the body, and their pathological relevance to gut inflammation in humans.

CRISPR-Cas9 applications in T cells and adoptive T cell therapies

T cell immunity is central to contemporary cancer and autoimmune therapies, encompassing immune checkpoint blockade and adoptive T cell therapies. Their diverse characteristics can be reprogrammed by different immune challenges dependent on antigen stimulation levels, metabolic conditions, and the degree of inflammation. T cell-based therapeutic strategies are gaining widespread adoption in oncology and treating inflammatory conditions. Emerging researches reveal that clustered regularly interspaced palindromic repeats-associated protein 9 (CRISPR-Cas9) genome editing has enabled T cells to be more adaptable to specific microenvironments, opening the door to advanced T cell therapies in preclinical and clinical trials. CRISPR-Cas9 can edit both primary T cells and engineered T cells, including CAR-T and TCR-T, in vivo and in vitro to regulate T cell differentiation and activation states. This review first provides a comprehensive summary of the role of CRISPR-Cas9 in T cells and its applications in preclinical and clinical studies for T cell-based therapies. We also explore the application of CRISPR screen high-throughput technology in editing T cells and anticipate the current limitations of CRISPR-Cas9, including off-target effects and delivery challenges, and envisioned improvements in related technologies for disease screening, diagnosis, and treatment.

Squalene Epoxidase: Its Regulations and Links with Cancers

Squalene epoxidase (SQLE) is a key enzyme in the mevalonate-cholesterol pathway that plays a critical role in cellular physiological processes. It converts squalene to 2,3-epoxysqualene and catalyzes the first oxygenation step in the pathway. Recently, intensive efforts have been made to extend the current knowledge of SQLE in cancers through functional and mechanistic studies. However, the underlying mechanisms and the role of SQLE in cancers have not been fully elucidated yet. In this review, we retrospected current knowledge of SQLE as a rate-limiting enzyme in the mevalonate-cholesterol pathway, while shedding light on its potential as a diagnostic and prognostic marker, and revealed its therapeutic values in cancers. We showed that SQLE is regulated at different levels and is involved in the crosstalk with iron-dependent cell death. Particularly, we systemically reviewed the research findings on the role of SQLE in different cancers. Finally, we discussed the therapeutic implications of SQLE inhibitors and summarized their potential clinical values. Overall, this review discussed the multifaceted mechanisms that involve SQLE to present a vivid panorama of SQLE in cancers.

Integrative systems biology reveals NKG2A-biased immune responses correlate with protection in infectious disease, autoimmune disease, and cancer

Infection, autoimmunity, and cancer are principal human health challenges of the 21st century. Often regarded as distinct ends of the immunological spectrum, recent studies hint at potential overlap between these diseases. For example, inflammation can be pathogenic in infection and autoimmunity. T resident memory (TRM) cells can be beneficial in infection and cancer. However, these findings are limited by size and scope; exact immunological factors shared across diseases remain elusive. Here, we integrate large-scale deeply clinically and biologically phenotyped human cohorts of 526 patients with infection, 162 with lupus, and 11,180 with cancer. We identify an NKG2A+ immune bias as associative with protection against disease severity, mortality, and autoimmune/post-acute chronic disease. We reveal that NKG2A+ CD8+ T cells correlate with reduced inflammation and increased humoral immunity and that they resemble TRM cells. Our results suggest NKG2A+ biases as a cross-disease factor of protection, supporting suggestions of immunological overlap between infection, autoimmunity, and cancer.

Functional Diversity of Memory CD8 T Cells is Spatiotemporally Imprinted

Tissue-resident memory CD8 T cells (TRM) kill infected cells and recruit additional immune cells to limit pathogen invasion at barrier sites. Small intestinal (SI) TRM cells consist of distinct subpopulations with higher expression of effector molecules or greater memory potential. We hypothesized that occupancy of diverse anatomical niches imprints these distinct TRM transcriptional programs. We leveraged human samples and a murine model of acute systemic viral infection to profile the location and transcriptome of pathogen-specific TRM cell differentiation at single-transcript resolution. We developed computational approaches to capture cellular locations along three anatomical axes of the small intestine and to visualize the spatiotemporal distribution of cell types and gene expression. TRM populations were spatially segregated: with more effector- and memory-like TRM preferentially localized at the villus tip or crypt, respectively. Modeling ligand-receptor activity revealed patterns of key cellular interactions and cytokine signaling pathways that initiate and maintain TRM differentiation and functional diversity, including different TGFβ sources. Alterations in the cellular networks induced by loss of TGFβRII expression revealed a model consistent with TGFβ promoting progressive TRM maturation towards the villus tip. Ultimately, we have developed a framework for the study of immune cell interactions with the spectrum of tissue cell types, revealing that T cell location and functional state are fundamentally intertwined.

T cell cholesterol transport is a metabolic checkpoint that links intestinal immune responses to dietary lipid absorption

The intrinsic pathways that control membrane organization in immune cells and the impact of such pathways on cellular function are not well defined. Here we report that the non-vesicular cholesterol transporter Aster-A links plasma membrane (PM) cholesterol availability in T cells to immune signaling and systemic metabolism. Aster-A is recruited to the PM during T-cell receptor (TCR) activation, where it facilitates the removal of newly generated "accessible" membrane cholesterol. Loss of Aster-A leads to excess PM cholesterol accumulation, resulting in enhanced TCR nano-clustering and signaling, and Th17 cytokine production. Finally, we show that the mucosal Th17 response is restrained by PM cholesterol remodeling. Ablation of Aster-A in T cells leads to enhanced IL-22 production, reduced intestinal fatty acid absorption, and resistance to diet-induced obesity. These findings delineate a multi-tiered regulatory scheme linking immune cell lipid flux to nutrient absorption and systemic physiology.

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.

The cellular composition of the tumor microenvironment is an important marker for predicting therapeutic efficacy in breast cancer

At present, the incidence rate of breast cancer ranks first among new-onset malignant tumors in women. The tumor microenvironment is a hot topic in tumor research. There are abundant cells in the tumor microenvironment that play a protumor or antitumor role in breast cancer. During the treatment of breast cancer, different cells have different influences on the therapeutic response. And after treatment, the cellular composition in the tumor microenvironment will change too. In this review, we summarize the interactions between different cell compositions (such as immune cells, fibroblasts, endothelial cells, and adipocytes) in the tumor microenvironment and the treatment mechanism of breast cancer. We believe that detecting the cellular composition of the tumor microenvironment is able to predict the therapeutic efficacy of treatments for breast cancer and benefit to combination administration of breast cancer.

Fatty Acid Oxidation Promotes Apoptotic Resistance and Proinflammatory Phenotype of CD4+ Tissue-resident Memory T cells in Crohn's Disease

BACKGROUND & AIMS

As the most abundant memory T cells and major source of tumor necrosis factor α in the intestinal mucosa of Crohn's disease (CD) patients, CD4+ tissue-resident memory T (TRM) cells play a critical role in CD pathogenesis. We investigated the role of metabolic reprogramming in the regulation of proinflammatory and apoptosis-resistant phenotype for CD4+ TRM cells.

METHODS

CD4+ TRM cells were collected from intestinal resection tissues from control and CD patients. Transcriptomic and metabolomic analysis were performed to identify metabolic characteristics of CD4+ TRM cells. Enzyme-linked immunosorbent assay and quantitative polymerase chain reaction experiments were used to assess cytokines level in CD4+ TRM cells; activation-induced cell apoptosis rate was evaluated by flow cytometry. Transwell assay and wound healing assay were performed to detect the effect of CD4+ TRM cells on the migration of normal intestinal epithelial cells.

RESULTS

Transcriptomic data combined with unbiased metabolomic analysis revealed an increased fatty acid oxidation (FAO) phenotype existed in CD4+ TRM cells from CD patients. The lipidomic data and stable isotope tracer experiments demonstrated that CD4+ TRM cells up-regulated their lipid lipolysis and fatty acid uptake to fuel FAO in CD patients. Mechanistically, the activated nuclear factor kappa B signaling increased transcription of genes involved in lipid lipolysis, fatty acid uptake, and oxidation in CD4+ TRM cells from CD patients. Targeting FAO of CD4+ TRM cells reversed their apoptosis-resistant and proinflammatory phenotype in CD patients.

CONCLUSIONS

CD4+ TRM cells process an accelerated FAO mediated by activated nuclear factor kappa B signaling in CD patients; targeting FAO could reverse their apoptosis-resistant and proinflammatory phenotype. These findings shed a new light on the pathogenic mechanism investigation and novel therapy development in CD patients.

The immune checkpoint TIGIT/CD155 promotes the exhaustion of CD8 + T cells in TNBC through glucose metabolic reprogramming mediated by PI3K/AKT/mTOR signaling

OBJECTIVE

The CD155/TIGIT axis has attracted considerable interest as an emerging immune checkpoint with potential applications in cancer immunotherapy. Our research focused on investigating the role of CD155/TIGIT checkpoints in the progression of triple-negative breast cancer (TNBC).

METHODS

We evaluated CD155 and TIGIT expression in TNBC tissues using both immunohistochemistry (IHC) and gene expression profiling. Our experiments, both in vivo and in vitro, provided evidence that inhibiting the CD155/TIGIT pathway reinstates the ability of CD8 + T cells to generate cytokines. To assess the impact of CD155/TIGIT signaling blockade, we utilized Glucose Assay Kits and Lactate Assay Kits to measure alterations in glucose and lactate levels within CD8 + T cells. We employed western blotting (WB) to investigate alterations in glycolytic-related proteins within the PI3K/AKT/mTOR pathways following the inhibition of CD155/TIGIT signaling.

RESULTS

CD155 exhibits heightened expression within TNBC tissues and exhibits a negative correlation with the extent of infiltrating CD8 + T cells. Furthermore, patients with TNBC demonstrate elevated levels of TIGIT expression. Our findings indicate that the interaction between CD155 and TIGIT disrupts the glucose metabolism of CD8 + T cells by suppressing the activation of the PI3K/AKT/mTOR signaling pathway, ultimately leading to the reduced production of cytokines by CD8 + T cells. Both in vivo and in vitro experiments have conclusively demonstrated that the inhibition of CD155/TIGIT interaction reinstates the capacity of CD8 + T cells to generate cytokines. Moreover, in vivo administration of the blocking antibody against TIGIT not only inhibits tumor growth but also augments the functionality of CD8 + T lymphocytes.

CONCLUSIONS

Our research findings strongly suggest that CD155/TIGIT represents a promising therapeutic target for treating TNBC.

Cristae formation is a mechanical buckling event controlled by the inner mitochondrial membrane lipidome

Cristae are high-curvature structures in the inner mitochondrial membrane (IMM) that are crucial for ATP production. While cristae-shaping proteins have been defined, analogous lipid-based mechanisms have yet to be elucidated. Here, we combine experimental lipidome dissection with multi-scale modeling to investigate how lipid interactions dictate IMM morphology and ATP generation. When modulating phospholipid (PL) saturation in engineered yeast strains, we observed a surprisingly abrupt breakpoint in IMM topology driven by a continuous loss of ATP synthase organization at cristae ridges. We found that cardiolipin (CL) specifically buffers the inner mitochondrial membrane against curvature loss, an effect that is independent of ATP synthase dimerization. To explain this interaction, we developed a continuum model for cristae tubule formation that integrates both lipid and protein-mediated curvatures. This model highlighted a snapthrough instability, which drives IMM collapse upon small changes in membrane properties. We also showed that cardiolipin is essential in low-oxygen conditions that promote PL saturation. These results demonstrate that the mechanical function of cardiolipin is dependent on the surrounding lipid and protein components of the IMM.

Roles of tissue-resident immune cells in immunotherapy of non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is the most common and lethal type of lung cancer, with limited treatment options and poor prognosis. Immunotherapy offers hope for improving the survival and quality of life of NSCLC patients, but its efficacy depends on the tumor immune microenvironment (TME). Tissue-resident immune cells are a subset of immune cells that reside in various tissues and organs, and play an important role in fighting tumors. In NSCLC, tissue-resident immune cells are heterogeneous in their distribution, phenotype, and function, and can either promote or inhibit tumor progression and response to immunotherapy. In this review, we summarize the current understanding on the characteristics, interactions, and roles of tissue-resident immune cells in NSCLC. We also discuss the potential applications of tissue-resident immune cells in NSCLC immunotherapy, including immune checkpoint inhibitors (ICIs), other immunomodulatory agents, and personalized cell-based therapies. We highlight the challenges and opportunities for developing targeted therapies for tissue-resident immune cells and optimizing existing immunotherapeutic approaches for NSCLC patients. We propose that tissue-resident immune cells are a key determinant of NSCLC outcome and immunotherapy response, and warrant further investigation in future research.

An NKG2A biased immune response confers protection for infection, autoimmune disease, and cancer

Infection, autoimmunity, and cancer are the principal human health challenges of the 21st century and major contributors to human death and disease. Often regarded as distinct ends of the immunological spectrum, recent studies have hinted there may be more overlap between these diseases than appears. For example, pathogenic inflammation has been demonstrated as conserved between infection and autoimmune settings. T resident memory (TRM) cells have been highlighted as beneficial for infection and cancer. However, these findings are limited by patient number and disease scope; exact immunological factors shared across disease remain elusive. Here, we integrate large-scale deeply clinically and biologically phenotyped human cohorts of 526 patients with infection, 162 with lupus, and 11,180 with cancer. We identify an NKG2A+ immune bias as associative with protection against disease severity, mortality, and autoimmune and post-acute chronic disease. We reveal that NKG2A+ CD8+ T cells correlate with reduced inflammation, increased humoral immunity, and resemble TRM cells. Our results suggest that an NKG2A+ bias is a pan-disease immunological factor of protection and thus supports recent suggestions that there is immunological overlap between infection, autoimmunity, and cancer. Our findings underscore the promotion of an NKG2A+ biased response as a putative therapeutic strategy.