Immune Cell Function Research Articles

T-Cell Senescence in Human Metabolic Diseases.

Immunosenescence denotes a state of dysregulated immune cell function characterized by a confluence of factors, including arrested cell cycle, telomere shortening, markers of cellular stress, mitochondrial dysfunction, loss of proteostasis, epigenetic reprogramming, and secretion of proinflammatory mediators. This state primarily manifests during the aging process but can also be induced in various pathological conditions, encompassing chronic viral infections, autoimmune diseases, and metabolic disorders. Age-associated immune system alterations extend to innate and adaptive immune cells, with T-cells exhibiting heightened susceptibility to immunosenescence. In particular, senescent T-cells have been identified in the context of metabolic disorders such as obesity, diabetes, and cardiovascular diseases. Recent investigations suggest a direct link between T-cell senescence, inflammation, and insulin resistance. The perturbation of biological homeostasis by senescent T-cells appears intricately linked to the initiation and progression of metabolic diseases, particularly through inflammation-mediated insulin resistance. Consequently, senescent T-cells are emerging as a noteworthy therapeutic target. This review aims to elucidate the intricate relationship between metabolic diseases and T-cell senescence, providing insights into the potential roles of senescent T-cells in the pathogenesis of metabolic disorders. Through a comprehensive examination of current research findings, this review seeks to contribute to a deeper understanding of the complex interplay between immunosenescence and metabolic health.

Sensory sentinels: Neuroimmune detection and food allergy.

Food allergy is classically characterized by an inappropriate type-2 immune response to allergenic food antigens. However, how allergens are detected and how that detection leads to the initiation of allergic immunity is poorly understood. In addition to the gastrointestinal tract, the barrier epithelium of the skin may also act as a site of food allergen sensitization. These barrier epithelia are densely innervated by sensory neurons, which respond to diverse physical environmental stimuli. Recent findings suggest that sensory neurons can directly detect a broad array of immunogens, including allergens, triggering sensory responses and the release of neuropeptides that influence immune cell function. Reciprocally, immune mediators modulate the activation or responsiveness of sensory neurons, forming neuroimmune feedback loops that may impact allergic immune responses. By utilizing cutaneous allergen exposure as a model, this review explores the pivotal role of sensory neurons in allergen detection and their dynamic bidirectional communication with the immune system, which ultimately orchestrates the type-2 immune response. Furthermore, it sheds light on how peripheral signals are integrated within the central nervous system to coordinate hallmark features of allergic reactions. Drawing from this emerging evidence, we propose that atopy arises from a dysregulated neuroimmune circuit.

The Impact of Liver Failure on the Immune System.

Liver failure profoundly affects the immune system, leading to dysregulation of innate and adaptive immune response. This review explores the intricate relationship between liver function and immune homeostasis. The role of the liver as a central hub in immune response initiation is elucidated, emphasizing its involvement in hepatic inflammation induction and subsequent systemic inflammation. Cytokines, chemokines, growth factors, and lipid mediators orchestrate these immune processes, serving as both prognostic biomarkers and potential therapeutic targets in liver failure-associated immune dysregulation, which might result from acute-on-chronic liver failure (ACLF) and cirrhosis. Furthermore, the review delves into the mechanisms underlying immunosuppression in liver failure, encompassing alterations in innate immune cell functions such as neutrophils, macrophages, and natural killer cells (NK cells), as well as perturbations in adaptive immune responses mediated by B and T cells. Conclusion: Understanding the immunological consequences of liver failure is crucial for developing targeted therapeutic interventions and improving patient outcomes in liver disease management.

Defining the immunological compatibility of graphene oxide-loaded PLGA scaffolds for biomedical applications

Graphene oxide (GO), a carbon-based nanomaterial, presents significant potential across biomedical fields such as bioimaging, drug delivery, biosensors, and phototherapy. This study examines the effects of integrating GO into poly(lactic-co-glycolic acid) (PLGA) scaffolds on human immune cell function. Our results demonstrate that high concentrations of GO reduce the viability of peripheral blood mononuclear cells (PBMCs) following stimulation with anti-CD3 antibody. This reduction extends to T lymphocyte activation, evident from the diminished proliferative response to T cell receptor engagement and impaired differentiation into T helper subsets and regulatory T cells. Interestingly, although GO induces a minimal response in resting monocytes, but it significantly affects both the viability and the differentiation potential of monocytes induced to mature toward M1 pro-inflammatory and M2-like immunoregulatory macrophages. This study seeks to address a critical gap by investigating the in vitro immunomodulatory effects of PLGA scaffolds incorporating various concentrations of GO on primary immune cells, specifically PBMCs isolated from healthy donors. Our findings emphasize the need to optimize the GO to PLGA ratios and scaffold design to advance PLGA-GO-based biomedical applications. Statement of significanceGraphene oxide (GO) holds immense promise for biomedical applications due to its unique properties. However, concerns regarding its potential to trigger adverse immune responses remain. This study addresses this critical gap by investigating the in vitro immunomodulatory effects of PLGA scaffolds incorporating increasing GO concentrations on human peripheral blood mononuclear cells (PBMCs). By elucidating the impact on cell viability, T cell proliferation and differentiation, and the maturation/polarization of antigen-presenting cells, this work offers valuable insights for designing safe and immunologically compatible GO-based biomaterials for future clinical translation.

Sunitinib-induced endocapillary proliferative glomerulonephritis with IgA2 deposit in addition to thrombotic microangiopathy: a case report

BackgroundSunitinib, a multi-targeted tyrosine kinase inhibitor, is used as a second-line therapy for gastrointestinal stromal tumors (GIST) resistant to imatinib. However, its impact on the vascular endothelial growth factor (VEGF) pathway can lead to significant toxicities, including hypertension and thrombotic microangiopathy (TMA).Case presentationThis case report describes a unique instance of a patient with metastatic GIST who developed endocapillary proliferative glomerulonephritis (EPGN) with IgA2 deposits and TMA following sunitinib treatment. The patient presented with severe hypertension, nephrotic syndrome, and acute kidney injury. Renal biopsy confirmed the diagnosis, revealing IgA2 deposits, which are not commonly associated with TMA. Discontinuation of sunitinib led to a rapid improvement in renal function and proteinuria. The potential mechanisms underlying sunitinib-induced glomerular injury may involve the blockade of VEGFR-1, affecting immune cell recruitment and function, and the disruption of the nitric oxide and endothelin systems, leading to endothelial damage and immune dysregulation. Management of these toxicities requires a personalized approach, with options ranging from symptomatic relief to drug discontinuation. The use of endothelin receptor antagonists and other therapeutic alternatives for GIST management is discussed.ConclusionsThis case highlights the complex interplay between the therapeutic effects of sunitinib and its potential renal and cardiovascular toxicities, emphasizing the need for close monitoring and effective management strategies to optimize patient outcomes.

Lipid-Based Nanoparticles Fused with Natural Killer Cell Plasma Membrane Proteins for Triple-Negative Breast Cancer Therapy.

Immunotherapy combined with chemicals and genetic engineering tools is emerging as a promising strategy to treat triple-negative breast cancer (TNBC), which is more aggressive with poorer progress than other breast cancer subtypes. In this study, lipid-based nanoparticles (LNPs) possessed an NK cell-like function that could deliver tumor-specific therapeutics and inhibit tumor growth. LNPs fused with an NK cell membrane protein system (NK-LNP) have three main features: (i) hydrophilic plasmid DNA can inhibit TNBC metastasis when encapsulated within LNPs and delivered to cells; (ii) the lipid composition of LNPs, including C18 ceramide, exhibits anticancer effects; (iii) NK cell membrane proteins are immobilized on the LNP surface, enabling targeted delivery to TNBC cells. These particles facilitate the targeted delivery of HIC1 plasmid DNA and the modulation of immune cell functions. Delivered therapeutic genes can inhibit metastasis of TNBC and then induce apoptotic cell death while targeting macrophages to promote cytokine release. The anticancer effect is expected to be applied in treating various difficult-to-treat cancers with LNP fused with NK cell plasma membrane proteins, which can simultaneously deliver therapeutic chemicals and genes.

Inhibition of DLL4/Notch Signaling Pathway Promotes M2 Polarization and Cell Proliferation in Pulmonary Arterial Hypertension.

In this study, we conducted a comprehensive analysis to identify key genes and pathways associated with pulmonary arterial hypertension (PAH) and investigated the role of delta-like ligand 4 (DLL4) in PAH pathogenesis. Through integrated analysis of multiple data sets, we identified 6 candidate differentially expressed genes (DEGs), notably DLL4, which showed the highest distinguishing efficiency between PAH and control samples. Functional and pathway enrichment analyses revealed the involvement of DLL4 in critical biological processes and pathways related to PAH, including notch signaling, immune cell function, and inflammatory responses. Further investigation demonstrated that decreased DLL4 expression correlated with increased M2 macrophage polarization, suggesting a potential role for DLL4 in preventing M2 differentiation. Additionally, the DLL4/Notch1 axis was found to influence the Notch profile and regulate signaling mediators during M2 differentiation. These findings highlight DLL4 as a promising biomarker and therapeutic target for PAH, shedding light on the underlying molecular mechanisms and providing insights for the development of novel treatment strategies.

Endocannabinoid regulation of inward rectifier potassium (Kir) channels.

The inward rectifier potassium channel Kir2.1 (KCNJ2) is an important regulator of resting membrane potential in both excitable and non-excitable cells. The functions of Kir2.1 channels are dependent on their lipid environment, including the availability of PI(4,5)P2, secondary anionic lipids, cholesterol and long-chain fatty acids acyl coenzyme A (LC-CoA). Endocannabinoids are a class of lipids that are naturally expressed in a variety of cells, including cardiac, neuronal, and immune cells. While these lipids are identified as ligands for cannabinoid receptors there is a growing body of evidence that they can directly regulate the function of numerous ion channels independently of CBRs. Here we examine the effects of a panel of endocannabinoids on Kir2.1 function and demonstrate that a subset of endocannabinoids can alter Kir2.1 conductance to varying degrees independently of CBRs. Using computational and Surface plasmon resonance analysis, endocannabinoid regulation of Kir2.1 channels appears to be the result of altered membrane properties, rather than through direct protein-lipid interactions. Furthermore, differences in endocannabinoid effects on Kir4.1 and Kir7.1 channels, indicating that endocannabinoid regulation is not conserved among Kir family members. These findings may have broader implications on the function of cardiac, neuronal and/or immune cells.

Targeting MELK in tumor cells and tumor microenvironment: from function and mechanism to therapeutic application.

Maternal embryonic leucine zipper kinase (MELK), a member of the adenosine monophosphate-activated protein kinase (AMPK) protein family, has been reported to be involved in the regulation of many cellular events. The aberrant expression of MELK is associated with tumorigenesis and malignant progression of various tumors. Moreover, MELK plays an essential role in the regulation of tumor microenvironment (TME), which affects the function of immune cells and the responsiveness to immunotherapy. Currently, small molecule inhibitors targeting MELK have been developed and evaluated in clinical trials. A comprehensive understanding of MELK may provide clues and confidence for subsequent basic research and scientific transformation. In this review, we provide a comprehensive overview of the structural features, molecular biological functions, and critical roles of MELK in tumors and TME, as well as the targeted agents under development for the treatment of tumors and discuss the perspective for MELK-targeted therapies for tumors.

Spatial diversity of in vivo tissue immunity.

The immune system exhibits spatial diversity in in vivo tissues. Immune cells are strategically distributed within tissues to maintain the organ integrity. Advanced technologies such as intravital imaging and spatial transcriptomics have revealed the spatial heterogeneity of immune cell distribution and function within organs such as the liver, kidney, intestine, and lung. In addition, these technologies visualize nutrient and oxygen environments across tissues. Recent spatial analyses have suggested that a functional immune niche is determined by interactions between immune and non-immune cells in an appropriate nutrient and oxygen environment. Understanding the spatial communication between immune cells, environment, and surrounding non-immune cells is crucial for developing strategies to control immune responses and effectively manage inflammatory diseases.

Renal L-2-hydroxyglutarate dehydrogenase activity promotes hypoxia tolerance and mitochondrial metabolism in Drosophila melanogaster

ObjectivesThe mitochondrial enzyme L-2-hydroxyglutarate dehydrogenase (L2HGDH) regulates the abundance of L-2-hydroxyglutarate (L-2HG), a potent signaling metabolite capable of influencing chromatin architecture, mitochondrial metabolism, and cell fate decisions. Loss of L2hgdh activity in humans induces ectopic L-2HG accumulation, resulting in neurodevelopmental defects, altered immune cell function, and enhanced growth of clear cell renal cell carcinomas. To better understand the molecular mechanisms that underlie these disease pathologies, we used the fruit fly Drosophila melanogaster to investigate the endogenous functions of L2hgdh. MethodsL2hgdh mutant adult male flies were analyzed under normoxic and hypoxic conditions using a combination of semi-targeted metabolomics and RNA-seq. These multi-omic analyses were complemented by tissue-specific genetic studies that examined the effects of L2hgdh mutations on the Drosophila renal system (Malpighian tubules; MTs). ResultsOur studies revealed that while L2hgdh is not essential for growth or viability under standard culture conditions, L2hgdh mutants are hypersensitive to hypoxia and expire during the reoxygenation phase with severe disruptions of mitochondrial metabolism. Moreover, we find that the fly renal system is a key site of L2hgdh activity, as L2hgdh mutants that express a rescuing transgene within the MTs survive hypoxia treatment and exhibit normal levels of mitochondrial metabolites. We also demonstrate that even under normoxic conditions, L2hgdh mutant MTs experience significant metabolic stress and are sensitized to aberrant growth upon Egfr activation. ConclusionsThese findings present a model in which renal L2hgdh activity limits systemic L-2HG accumulation, thus indirectly regulating the balance between glycolytic and mitochondrial metabolism, enabling successful recovery from hypoxia exposure, and ensuring renal tissue integrity.

Divergent Immediate and Delayed Effects of Juvenile Exposure to Doxorubicin on the Thymus in C57BL/6 Mice.

The understanding of alterations within the immune system following doxorubicin (DOX) chemotherapy, and subsequent restoration, in childhood cancer survivors remains limited. This investigation endeavors to elucidate the immediate and delayed changes in thymic immune cell populations and their phenotypes in response to clinically relevant low doses of DOX in a juvenile mouse model. Male mice underwent a regimen of repeated low-dose DOX intraperitoneal injections at 4 mg/kg/week for three consecutive weeks. One week after the last dose of DOX, a subset of mice was euthanized to assess the immediate effects of DOX administration. A second subset of mice was euthanized five weeks after the last DOX dose to evaluate the delayed effects. Thymic samples were collected for multiparameter flow cytometry analysis to evaluate alterations in immune cell composition and phenotype. Additionally, quantitative real-time polymerase chain reaction (qRT-PCR) was employed to measure gene expression of- cytokines and senescence markers. One week following DOX administration, DOX treatment resulted in significant decline in thymus weight, with notable alterations in immune cell subpopulations. Reduced frequencies of mature CD3+CD4+ and CD3+CD8+ T cells were observed, along with changes in proliferation and exhaustion markers. Gene expression analysis revealed upregulation of Foxn, Pax1, Ifnγ, and Il7 alongside decreased Il6 and Il17 expression. Furthermore, Cdkn1a (p21Cip1) expression was elevated, suggesting immunosenescence. Five weeks following DOX administration, delayed effects of DOX treatment manifested in rebound increase in thymus weight and altered frequencies of CD4+ and CD8+ T cell subsets, with distinct patterns of proliferation and exhaustion observed. Notably, central memory CD4+ T cells exhibited significant decrease in frequency, while naive and effector memory CD4+ T cells showed reduced proliferation (Ki67+) and PD1 expression. Similar trends were observed in CD8+ T cell subsets, indicating selective effects of DOX on T cell differentiation and function. Although expression of thymus-related genes was normalized, p21Cip1 gene expression remained elevated. DOX treatment elicits a multifaceted influence on immune cell subsets and thymic weight. Immediate effects included thymic atrophy and reductions in mature T cell populations, while delayed effects showed rebound thymic hyperplasia and selective changes in CD4+ and CD8+ T cell subsets. Notably, both central memory and effector memory T cells exhibited reduced proliferation and exhaustion, suggesting unique impacts of DOX on immune cell function. The enduring elevation in p21Cip1 gene expression 5 weeks after DOX treatment suggests an immunosenescent phenotype. These observations collectively illuminate the formidable task of preserving immune competence and overall well-being in childhood cancer survivors subjected to DOX therapy.

A Review of Cholinergic Acid's Antioxidant Potential in Age-Related Eye Disorders

Sepsis is a disordered host response to an infection, and one of its hallmarks is organ failure. Mitochondria appear to be a key actor in the chain of events that results in multiple organ failure and potentially death, despite the pathophysiology being complex and little understood. Apart from supplying energy and metabolic intermediates required for immune cell activation and function, mitochondria also impact inflammation and cell death pathways. These two functions of mitochondria influence immunological responses. Crucially, the stability of end organ metabolism and the efficacy of the immune system are both compromised by mitochondrial dysfunction. A hyperinflammatory state and a lack of cellular homeostasis are further consequences of malfunctioning mitochondria, which also contribute to poor clinical outcomes. Hence, strategies to maximize mitochondrial efficiency are necessary since signs of mitochondrial malfunction are evident even in early stages of sepsis. Replacing or repairing damaged mitochondria may therefore aid in the recovery of organ function in sepsis. Toward the conclusion.

Effect of Menopausal Hormone Therapy on Cellular Immunity Parameters and Cytokine Profile.

A woman's entry into the menopause period is associated with a number of changes in the body, including those related to the immune system. Immune aging is a consequence of age-related changes in the function of immune cells and the composition of their subpopulations. Menopausal hormone therapy (MHT) is thought to partially neutralize the negative effects of aging on the immune system. We aimed to evaluate the effect of oral and transdermal MHT on cellular immunity parameters and cytokine profile in menopausal women. Fifty peri- and early postmenopausal women were included. Immune parameters were assessed by flow cytometry and multiplex analysis. We showed that different routes of MHT administration led to significant changes in monocyte phenotype and a decrease in monocyte chemoattractant protein-1 (MCP-1) level in menopausal patients. In addition, oral MHT resulted in a significant increase in NK and B cells. A significant increase in the number of T-helper cells was observed with transdermal MHT. In addition, oral MHT resulted in a significant decrease in IL-1β level. We have demonstrated for the first time that oral therapy, in contrast to transdermal therapy, has a more pronounced effect on specific immune subpopulations of blood cells in menopausal women. This effect is likely to be responsible for its anti-aging properties in the context of immune aging as well as its protective effects in infectious diseases. Perhaps testing blood immune parameters or assessing immune status before prescribing MHT could become a routine step in clinical practice before choosing a patient management strategy.

Recent Advances in Biomaterials for mRNA Delivery to Immune Cells.

Modulating the function of immune cells by targeting the cells themselves has become a key strategy in immunotherapy for combating various diseases such as cancer, autoimmune disorders, and infectious ailments. The use of mRNA (mRNA) is a powerful tool for transiently inducing protein expression, which is often used for genetic manipulation. However, its inherent instability and inability to precisely reach target cells necessitate the use of biomaterials for safe and effective delivery. Additionally, transfecting immune cells is difficult and complex due to their resistance mechanisms, signaling pathways, and cellular interactions. This review focuses on the recent development of biomaterials for mRNA delivery to immune cells, including lipid nanoparticles and polymeric carriers. It also outlines the challenges of targeting and delivering therapeutic payloads to immune cells, providing commentary and outlook on the design of next-generation materials. Finally, this approach has the potential to significantly enhance the precision and effectiveness of therapeutic interventions for various diseases, shaping the future of mRNA delivery for immune conditions.

Manganese-mediated potentiation of antitumor immune responses by enhancing KLRG1+ Macrophage function

Manganese (Mn) play a crucial role in various biological processes in the body. Studies have primarily focused on their ability to enhance immune cell function and activation against tumors, particularly in dendritic cells (DCs), macrophages, and T cells. Tumor-associated macrophages (TAMs) are often the most abundant immune cell population present in the tumor microenvironment (TME). Thus, it would be valuable to investigate the mechanism by which Mn2+ regulates TAMs’ involvement in anti-tumor immunity, as it be crucial for advancing our understanding of cancer biology and developing new treatments for cancer. Here, in the present study we discovered that Mn2+ treatment led to a significant increase in KLRG1+ macrophages (KLRG1+ Mφ) in tumor tissues, and most of these cells exhibited an M1 phenotype. Knocking down KLRG1 in macrophages not only impaired their ability to induce downstream anti-tumor immunity of adaptive immune cells, but also impaired their direct cytotoxicity against tumor cells. Moreover, the changes in the polarization phenotype of KLRG1+ macrophages further lead to T cell proliferation and the polarization of CD4+ T cells towards a Th1 phenotype, thereby establishing a foundation for the antitumor immune response. Our study expands the understanding of the anti-tumor mechanism of Mn2+ and demonstrates, for the first time, that Mn2+ can regulate the function of KLRG1+ Mφ to participate in anti-tumor activities. These findings suggest that KLRG1 may represent a promising target for developing new tumor therapy.

A prognostic model constructed by ferroptosis-associated genes (FAGs) in papillary renal cell carcinoma (PRCC) and its association with tumor mutation burden (TMB) and immune infiltration.

This study aimed to identify the prognostic-related differentially expressed ferroptosis-associated genes (DEFAGs) in papillary renal cell carcinoma (PRCC). Data encompassing simple nucleotide variation, transcriptome profiles, and relevant clinical information of PRCC patients were sourced from The Cancer Genome Atlas (TCGA) database. The expression matrix of ferroptosis-associated genes (FAGs) was analyzed using the "limma" package in R to identify differentially expressed DEFAGs. Lasso regression analysis, along with univariate and multivariate Cox proportional hazards regressions, was employed to identify independent prognostic-related DEFAGs and formulate a nomogram. Additionally, we examined potential independent survival-related clinical risk factors and compared immune cell infiltration and tumor mutation burden (TMB) differences between high- and low-risk patient groups. A cohort of 321 patients were analyzed, revealing twelve FAGs significantly influencing the overall survival (OS) of PRCC patients. Among them, two mRNAs (GCLC, HSBP1) emerged as independent prognostic-related DEFAGs. Smoking status, tumor stage, and risk score were identified as independent clinical risk factors for PRCC. Furthermore, notable disparities in immune cell infiltration and function were observed between high- and low-risk groups. GCLC and HSBP1 were associated with various immune cells and functions, TMB, and immune evasion. This finding revealed two independent prognostic-related DEFAGs in PRCC and established a robust prognostic model, offering potential therapeutic targets and promising insights for the management of this disease.

Experimental studies linking Alzheimer's Disease and changes in immune cell function

Alzheimer's disease (hereafter referred to as AD), which is a neurodegenerative malady, featured basically by memory deficiency and cognitive decrease, has been increasingly linked to immune system dynamics in recent studies. This paper aims to review experimental studies that elucidate the relationship between AD and alterations in immune cell functionality. Recent research has shown progress in this area through experiments, highlighting quantitative and functional shifts in T cells, macrophages, neutrophils, and B cells on the growth of AD. The assay insinuates pro-inflammatory cells rising and a decrease in inflammation-suppressing cells. These findings offer valuable insights for future mechanistic investigations and drug development. However, there remain numerous unexplored aspects in this field, such as specific factors exacerbating AD, drug treatments, and the identification of signaling pathways. Future research may benefit from focusing on uncovering signaling pathways as a key avenue for further exploration and understanding.

A potential mechanism of tumor immune escape: Regulation and application of soluble natural killer group 2 member D ligands (Review).

The immune system is integral to the surveillance and eradication of tumor cells. Interactions between the natural killer group 2 member D (NKG2D) receptor and its ligands (NKG2DLs) are vital for activating NKG2D receptor‑positive immune cells, such as natural killer cells. This activation enables these cells to identify and destroy tumor cells presenting with NKG2DLs, which is an essential aspect of tumor immunity. However, tumor immune escape is facilitated by soluble NKG2DL (sNKG2DL) shed from the surface of tumor cells. The production of sNKG2DL is predominantly regulated by metalloproteinases [a disintegrin and metalloproteinases (ADAM) and matrix metalloproteinase (MMP) families] and exosomes. sNKG2DL not only diminish immune recognition on the tumor cell surface but also suppress the function of immune cells, such as NK cells, and reduce the expression of the NKG2D receptor. This process promotes immune evasion, progression, and metastasis of tumors. In this review, an in‑depth summary of the mechanisms and factors that influence sNKG2DL production and their contribution to immune suppression within the tumor microenvironment are provided. Furthermore, due to the significant link between sNKG2DLs and tumor progression and metastasis, they have great potential as novel biomarkers. Detectable via liquid biopsies, sNKG2DLs could assess tumor malignancy and prognosis, and act as pivotal targets for immunotherapy. This could lead to the discovery of new drugs or the enhancement of existing treatments. Thus, the application of sNKG2DLs in clinical oncology was explored, offering substantial theoretical support for the development of innovative immunotherapeutic strategies for sNKG2DLs.

Targeting amino acid-metabolizing enzymes for cancer immunotherapy.

Despite the immune system's role in the detection and eradication of abnormal cells, cancer cells often evade elimination by exploitation of various immune escape mechanisms. Among these mechanisms is the ability of cancer cells to upregulate amino acid-metabolizing enzymes, or to induce these enzymes in tumor-infiltrating immunosuppressive cells. Amino acids are fundamental cellular nutrients required for a variety of physiological processes, and their inadequacy can severely impact immune cell function. Amino acid-derived metabolites can additionally dampen the anti-tumor immune response by means of their immunosuppressive activities, whilst some can also promote tumor growth directly. Based on their evident role in tumor immune escape, the amino acid-metabolizing enzymes glutaminase 1 (GLS1), arginase 1 (ARG1), inducible nitric oxide synthase (iNOS), indoleamine 2,3-dioxygenase 1 (IDO1), tryptophan 2,3-dioxygenase (TDO) and interleukin 4 induced 1 (IL4I1) each serve as a promising target for immunotherapeutic intervention. This review summarizes and discusses the involvement of these enzymes in cancer, their effect on the anti-tumor immune response and the recent progress made in the preclinical and clinical evaluation of inhibitors targeting these enzymes.