Trans-endocytosis of CD80 and CD86: a molecular basis for the cell-extrinsic function of CTLA-4

Emerging trends and therapeutic applications of monoclonal antibodies

Monoclonal antibodies (mAbs) are being used to prevent, detect, and treat a broad spectrum of malignancies and infectious and autoimmune diseases. Over the past few years, the market for mAbs has grown exponentially. They have become a significant part of many pharmaceutical product lines, and more than 250 therapeutic mAbs are undergoing clinical trials. Ever since the advent of hybridoma technology, antibody-based therapeutics were realized using murine antibodies which further progressed into humanized and fully human antibodies, reducing the risk of immunogenicity. Some of the benefits of using mAbs over conventional drugs include a drastic reduction in the chances of adverse reactions, interactions between drugs, and targeting specific proteins. While antibodies are very efficient, their higher production costs impede the process of commercialization. However, their cost factor has been improved by developing biosimilar antibodies, which are affordable versions of therapeutic antibodies. Along with biosimilars, innovations in antibody engineering have helped to design bio-better antibodies with improved efficacy than the conventional ones. These novel mAb-based therapeutics are set to revolutionize existing drug therapies targeting a wide spectrum of diseases, thereby meeting several unmet medical needs. In the future, mAbs generated by applying next-generation sequencing (NGS) are expected to become a powerful tool in clinical therapeutics. This article describes the methods of mAb production, pre-clinical and clinical development of mAbs, approved indications targeted by mAbs, and novel developments in the field of mAb research.

Context-restricted PD-(L)1 checkpoint agonism by CTLA4-Ig therapies inhibits T cell activity

T cell surface CTLA4 sequesters the costimulatory ligands CD80 and CD86 on antigen-presenting cells (APCs) to prevent autoimmunity. Therapeutic immunosuppression by recombinant CTLA4-immunoglobulin (Ig) fusion proteins, including abatacept, is also attributed to CD80/CD86 blockade. Recent studies show that CTLA4-Ig binding to APC surface cis-CD80:PD-L1 complexes can release the inhibitory ligand PD-L1, but whether this contributes to T cell inhibition remains unclear. Here, we show that PD-L1 liberation by CTLA4-Ig is strictly limited, both in extent and context, relative to PD-L1-competing anti-CD80 antibodies. At APC surface CD80:PD-L1 ratios exceeding 2:1, CTLA4-Ig therapies fail to release PD-L1 regardless of their CD80 affinity. Additionally, introducing flexibility into CTLA4-Ig by modifying its rigid homodimer interface produces biologics that retain bivalent CD80 binding without dissociating cis-bound PD-L1. These findings demonstrate that CTLA4-Ig therapies liberate PD-L1 through a CD80 reorientation mechanism that imposes a strict context dependence to their PD-1 checkpoint agonism and resultant T cell inhibition.

Unraveling the pathogenic interplay between SARS-CoV-2 and polycystic ovary syndrome using bioinformatics and experimental validation

The prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among polycystic ovary syndrome (PCOS) is significantly higher than in the general population. However, the mechanisms underlying this remain obscure. This study aimed to explore the mechanisms by identifying the genetic signature of SARS-CoV-2 infection in PCOS. In the present study, a total of 27 common differentially expressed genes (DEGs) were selected for subsequent analyses. Functional analyses showed that immunity and hormone-related pathways collectively participated in the development and progression of PCOS and SARS-CoV-2 infection. Under these, 7 significant hub genes were identified, including S100A9, MMP9, TLR2, THBD, ITGB2, ICAM1, and CD86 by using the algorithm in Cytoscape. Furthermore, hub gene expression was confirmed in the validation set, PCOS clinical samples, and mouse model. Immune microenvironment analysis with the CIBERSORTx database demonstrated that the hub genes were significantly correlated with T cells, dendritic cells, mast cells, B cells, NK cells, and eosinophils and positively correlated with immune scores. Among the hub genes, S100A9, MMP9, THBD, ITGB2, CD86, and ICAM1 demonstrated potential as possible diagnostic markers for COVID-19 and PCOS. In addition, we established the interaction networks of ovary-specific genes, transcription factors, miRNAs, drugs, and chemical compounds with hub genes with NetworkAnalyst. This work uncovered the common pathogenesis and genetic signature of PCOS and SARS-CoV-2 infection, which might provide a theoretical basis and innovative ideas for further mechanistic research and drug discovery of the comorbidity of the two diseases.

Combining RAS(ON) G12C-selective inhibitor with SHP2 inhibition sensitises lung tumours to immune checkpoint blockade

Mutant selective drugs targeting the inactive, GDP-bound form of KRASG12C have been approved for use in lung cancer, but resistance develops rapidly. Here we use an inhibitor, (RMC-4998) that targets RASG12C in its active, GTP-bound form, to treat KRAS mutant lung cancer in various immune competent mouse models. RAS pathway reactivation after RMC-4998 treatment could be delayed using combined treatment with a SHP2 inhibitor, which not only impacts tumour cell RAS signalling but also remodels the tumour microenvironment to be less immunosuppressive. In an immune inflamed model, RAS and SHP2 inhibitors in combination drive durable responses by suppressing tumour relapse and inducing development of immune memory. In an immune excluded model, combined RAS and SHP2 inhibition sensitises tumours to immune checkpoint blockade, leading to efficient tumour immune rejection. These preclinical results demonstrate the potential of the combination of RAS(ON) G12C-selective inhibitors with SHP2 inhibitors to sensitize tumours to immune checkpoint blockade.

Sex differences in human pre-gastrulation embryos

Human fetuses exhibit notable sex differences in growth rate and response to the intrauterine environment, yet their origins and underlying mechanisms remain uncertain. Here, we conduct a detailed investigation of sex differences in human pre-gastrulation embryos. The lower methylation and incomplete inactivation of the X chromosome in females, as well as the sex-specific cell-cell communication patterns, contribute to sex-differential transcription. Male trophectoderm is more inclined toward syncytiotrophoblast differentiation and exhibits a stronger hormone secretion capacity, while female trophectoderm tends to retain cytotrophoblast program with stronger mitochondrial function as well as higher vasculogenesis and immunotolerance signals. Male primitive endoderm initiates the anterior visceral endoderm transcriptional program earlier than females. The cell cycle activities of the epiblast and primitive endoderm are higher in males compared to females, while the situation is opposite in the trophectoderm. In conclusion, our study provides in-depth insights into the sex differences in human pre-gastrulation embryos and contributes to unraveling the origins of the sex differences in human fetal development.

Rigid, bivalent CTLA-4 binding to CD80 is required to disrupt the cis CD80/PD-L1 interaction

The CTLA-4 and PD-1 checkpoints control immune responses and are key targets in immunotherapy. Both pathways are connected via a cis interaction between CD80 and PD-L1, the ligands for CTLA-4 and PD-1, respectively. This cis interaction prevents PD-1-PD-L1 binding but is reversed by CTLA-4 trans-endocytosis of CD80. However, how CTLA-4 selectively removes CD80, but not PD-L1, is unclear. Here, we show CTLA-4-CD80 interactions are unimpeded by PD-L1 and that CTLA-4 binding with CD80 does not displace PD-L1 per se. Rather, both rigidity and bivalency of CTLA-4 molecules are required to orientate CD80 such that PD-L1 interactions are no longer permissible. Moreover, soluble CTLA-4 released PD-L1 only at specific expression levels of CD80 and PD-L1, whereas CTLA-4 trans-endocytosis released PD-L1 in all conditions. These data show that PD-L1 release from CD80 is driven by orientation and bivalent cross-linking of membrane proteins and that trans-endocytosis of CD80 efficiently promotes PD-L1 availability.

Immune suppression by human thymus-derived effector Tregs relies on glucose/lactate-fueled fatty acid synthesis

Regulatory T cells (Tregs) suppress pro-inflammatory conventional T cell (Tconv) responses. As lipids impact cell signaling and function, we compare the lipid composition of CD4+ thymus-derived (t)Tregs and Tconvs. Lipidomics reveal constitutive enrichment of neutral lipids in Tconvs and phospholipids in tTregs. TNFR2-co-stimulated effector tTregs and Tconvs are both glycolytic, but only in tTregs are glycolysis and the tricarboxylic acid (TCA) cycle linked to a boost in fatty acid (FA) synthesis (FAS), supported by relevant gene expression. FA chains in tTregs are longer and more unsaturated than in Tconvs. In contrast to Tconvs, tTregs effectively use either lactate or glucose for FAS and rely on this process for proliferation. FASN and SCD1, enzymes responsible for FAS and FA desaturation, prove essential for the ability of tTregs to suppress Tconvs. These data illuminate how effector tTregs can thrive in inflamed or cancerous tissues with limiting glucose but abundant lactate levels.

Indirect suppression of CD4 T cell activation through LAG-3-mediated trans-endocytosis of MHC class II

Blockade of immune checkpoint receptors has shown outstanding efficacy for tumor immunotherapy. Promising treatment with anti-lymphocyte-activation gene-3 (LAG-3) has already been recognized as the next efficacious treatment, but there is still limited understanding of the mechanism of LAG-3-mediated immune suppression. Here, utilizing high-resolution molecular imaging, we find a mechanism of CD4 T cell suppression via LAG-3, in which LAG-3-bound major histocompatibility complex (MHC) class II molecules on antigen-presenting cells (APCs) gather at the central region of an immunological synapse and are trans-endocytosed by T cell receptor-driven internalization motility toward CD4 and CD8 T cells expressing LAG-3. Downregulation of MHC class II molecules on APCs thus results in the attenuation of their antigen-presentation function and impairment of CD4 T cell activation. From these data, anti-LAG-3 treatment is suggested to have potency to directly block the inhibitory signaling via LAG-3 and simultaneously reduce MHC class II expression on APCs by LAG-3-mediated trans-endocytosis for recovery from T cell exhaustion.

Revolutionizing Cancer Treatment: Recent Advances in Immunotherapy

Cancer immunotherapy has emerged as a transformative approach in oncology, utilizing the body's immune system to specifically target and destroy malignant cells. This review explores the scope and impact of various immunotherapeutic strategies, including monoclonal antibodies, chimeric antigen receptor (CAR)-T cell therapy, checkpoint inhibitors, cytokine therapy, and therapeutic vaccines. Monoclonal antibodies, such as Rituximab and Trastuzumab, have revolutionized treatment paradigms for lymphoma and breast cancer by offering targeted interventions that reduce off-target effects. CAR-T cell therapy presents a potentially curative option for refractory hematologic malignancies, although challenges remain in effectively treating solid tumors. Checkpoint inhibitors have redefined the management of cancers like melanoma and lung cancer; however, managing immune-related adverse events and ensuring durable responses are critical areas of focus. Cytokine therapy continues to play a vital role in modulating the immune response, with advancements in cytokine engineering improving specificity and reducing systemic toxicity. Therapeutic vaccines, particularly mRNA-based vaccines, represent a frontier in personalized cancer treatment, aiming to generate robust, long-lasting immune responses against tumor-specific antigens. Despite these advancements, the field faces significant challenges, including immune resistance, tumor heterogeneity, and the immunosuppressive tumor microenvironment. Future research should address these obstacles through emerging technologies, such as next-generation antibodies, Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR)-based gene editing, and AI-driven drug discovery. By integrating these novel approaches, cancer immunotherapy holds the promise of offering more durable, less toxic, and highly personalized treatment options, ultimately improving patient outcomes and survival rates.

Striking a balance: new perspectives on homeostatic dendritic cell maturation

Dendritic cells (DCs) are crucial gatekeepers of the balance between immunity and tolerance. They exist in two functional states, immature or mature, that refer to an information-sensing versus an information-transmitting state, respectively. Historically, the term DC maturation was used to describe the acquisition of immunostimulatory capacity by DCs following their triggering by pathogens or tissue damage signals. As such, immature DCs were proposed to mediate tolerance, whereas mature DCs were associated with the induction of protective T cell immunity. Later studies have challenged this view and unequivocally demonstrated that two distinct modes of DC maturation exist, homeostatic and immunogenic DC maturation, each with a distinct functional outcome. Therefore, the mere expression of maturation markers cannot be used to predict immunogenicity. How DCs become activated in homeostatic conditions and maintain tolerance remains an area of intense debate. Several recent studies have shed light on the signals driving the homeostatic maturation programme, especially in the conventional type 1 DC (cDC1) compartment. Here, we highlight our growing understanding of homeostatic DC maturation and the relevance of this process for immune tolerance.

The molecular landscape of T cell exhaustion in the tumor microenvironment and reinvigoration strategies

Immunotherapy has emerged as a promising therapeutic approach for cancer treatment by harnessing the immune system to target cancer cells. However, the efficacy of immunotherapy is hindered by the tumor microenvironment (TME), comprising regulatory T cells (Tregs), macrophages, myeloid-derived suppressor cells (MDSCs), neutrophils, soluble factors (TGF-β, IL-35, IL-10), and hypoxia. These components interact with inhibitory receptors (IRs) on T cells, leading to alterations in T cell transcriptomes, epigenomes, and metabolism, ultimately resulting in T cell exhaustion and compromising the effectiveness of immunotherapy. T cell exhaustion occurs in two phases: pre-exhaustion and exhaustion. Pre-exhausted T cells exhibit reversibility and distinct molecular properties compared to terminally exhausted T cells. Understanding these differences is crucial for designing effective interventions. This comprehensive review summarizes the characteristics of pre-exhausted and exhausted T cells and elucidates the influence of TME components on T cell activity, transcriptomes, epigenomes, and metabolism, ultimately driving T cell exhaustion in cancer. Additionally, potential intervention strategies for reversing exhaustion are discussed. By gaining insights into the mechanisms underlying T cell exhaustion and the impact of the TME, this review aims to inform the development of innovative approaches for combating T cell exhaustion and enhancing the efficacy of immunotherapy in cancer treatment.

Identification of divergent placental profiles in clinically distinct pregnancy complications revealed by the transcriptome

INTRODUCTION

Pregnancy complications, including preeclampsia (PE), preterm birth (PTB), and intra-uterine growth restriction (IUGR) have individually been associated with inflammation but the combined comparative analysis of their placental profiles at the transcriptomic and histological levels is lacking.

METHODS

Bulk RNA-sequencing of human placental biopsies from uncomplicated term pregnancies (CTL) and pregnancies complicated with early-onset (EO), and late-onset (LO) PE, as well as PTB and term IUGR were used to characterize individual molecular profiles. We also applied immune-cell-specific cellular deconvolution to address local immune cell compositions and analyzed placental lesions by histology to further characterize these complications.

RESULTS

Transcriptome analysis revealed that clinically distinct complications differentiated themselves in unique ways compared to CTLs. Only TMEM136 was commonly modulated. Compared to CTLs, we found that PTB and IUGR were the most distinct, with LOPE being the least distinct. PTB and IUGR revealed differently enhanced inflammatory pathways, where PTB had general inflammatory responses and IUGR had immune cell activation. This inflammation was reflected in the histological profile for PTB only, whereas structural lesions were elevated in all complications. Placental lesions additionally had corresponding enhancement in inflammatory and structural biological processes. We observed that having co-complications, particularly for PTB with or without IUGR, impacted placental transcriptomes. Lastly, cellular deconvolution uncovered shared immune features among the complications.

DISCUSSION

Overall, we provide evidence that these pregnancy complications are not only distinct in their clinical manifestations but also in their placental profiles, which could be leveraged to understand their underlying mechanisms and could offer therapeutic targets.

Advances in immunotherapy for breast cancer and feline mammary carcinoma: From molecular basis to novel therapeutic targets

The role of inflammation in cancer is a topic that has been investigated for many years. As established, inflammation emerges as a defining characteristic of cancer, presenting itself as a compelling target for therapeutic interventions in the realm of oncology. Controlling the tumor microenvironment (TME) has gained paramount significance, modifying not only the effectiveness of immunotherapy but also modulating the outcomes and prognoses of standard chemotherapy and other anticancer treatments. Immunotherapy has surfaced as a central focus within the domain of tumor treatments, using immune checkpoint inhibitors as cancer therapy. Immune checkpoints and their influence on the tumor microenvironment dynamic are presently under investigation, aiming to ascertain their viability as therapeutic interventions across several cancer types. Cancer presents a significant challenge in humans and cats, where female breast cancer ranks as the most prevalent malignancy and feline mammary carcinoma stands as the third most frequent. This review seeks to summarize the data about the immune checkpoints cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), lymphocyte activation gene-3 (LAG-3), programmed cell death protein-1 (PD-1), V-domain Ig suppressor of T cell activation (VISTA), and T-cell immunoglobulin and mucin domain 3 (TIM-3) respective ongoing investigations as prospective targets for therapy for human breast cancer, while also outlining findings from studies reported on feline mammary carcinoma (FMC), strengthening the rationale for employing FMC as a representative model in the exploration of human breast cancer.

A study on the efficacy and Safety Evaluation of a novel PD-1/CTLA-4 bispecific antibody

Tumors constitute a significant health concern for humans, and PD-1 and CTLA-4 monoclonal antibodies have been proven effective in cancer treatment. Some researchers have identified that the combination of PD-1 and CTLA-4 dual blockade demonstrates superior therapeutic efficacy. However, the development of PD-1/CTLA-4 bispecific antibodies faces challenges in terms of both safety and efficacy. The present study discloses a novel PD-1/CTLA-4 bispecific antibody, designated as SH010. Experimental validation through surface plasmon resonance (SPR) confirmed that SH010 exhibits favorable binding activity with both PD-1 and CTLA-4. Flow cytometry analysis demonstrated stable binding of SH010 antibody to CHOK1 cells overexpressing human or cynomolgus monkey PD-1 protein and to 293F cells overexpressing human or cynomolgus monkey CTLA-4 protein. Moreover, it exhibited excellent blocking capabilities in protein binding between human PD-1 and PD-L1, as well as human CTLA-4 and CD80/CD86. Simultaneously, in vitro experiments indicate that SH010 exerts a significant activating effect on hPBMCs. In murine transplant models of human prostate cancer (22RV1) and small cell lung cancer (NCI-H69), administration of varying concentrations of the bispecific antibody significantly inhibits tumor growth. MSD analysis revealed that stimulation of hPBMCs from three different donors with SH010 did not induce the production of cytokine release syndrome. Furthermore, Single or repeated intravenous administrations of SH010 in cynomolgus monkeys show favorable systemic exposure without noticeable drug accumulation or apparent toxicity. In conclusion, SH010 represents a novel cancer therapeutic drug poised to enter clinical trials and obtain market approval.

Rewiring the T cell-suppressive cytokine landscape of the tumor microenvironment: a new frontier for precision anti-cancer therapy

T lymphocytes that infiltrate the tumor microenvironment (TME) often fail to function as effective anti-cancer agents. Within the TME, cell-to-cell inhibitory interactions play significant roles in dampening their anti-tumor activities. Recent studies have revealed that soluble factors released in the TME by immune and non-immune cells, as well as by tumor cells themselves, contribute to the exacerbation of T cell exhaustion. Our understanding of the cytokine landscape of the TME, their interrelationships, and their impact on cancer development is still at its early stages. In this review, we aim to shed light on Interleukin (IL) -6, IL-9, and IL-10, a small group of JAK/STAT signaling-dependent cytokines harboring T cell-suppressive effects in the TME and summarize their mechanisms of action. Additionally, we will explore how advancements in scientific research can help us overcoming the obstacles posed by cytokines that suppress T cells in tumors, with the ultimate objective of stimulating further investigations for the development of novel therapeutic strategies to counteract their tumor-promoting activities.

Excess generation and activation of naturally arising memory-phenotype CD4+ T lymphocytes are inhibited by regulatory T cells in steady state

Conventional CD4+ T lymphocytes consist of naïve, foreign antigen-specific memory, and self-antigen-driven memory-phenotype (MP) cell compartments at homeostasis. We recently showed that MP cells tonically proliferate in response to self-antigens and differentiate into the T-bet+ subset in steady state. How excess proliferation and differentiation of MP cells are inhibited remains unclear. Given immunosuppressive function of regulatory T cells (Tregs), it is possible that they are also involved in inhibition of spontaneous MP cell activation. Here we show using Foxp3-diphtheria toxin receptor-transgenic mice that both MP and naïve CD4+ T cells spontaneously proliferate and differentiate into Th1 cells upon acute Treg depletion. At an early time point post Treg depletion, MP as compared to naïve CD4+ T cells are preferentially activated while at a later stage, the response is dominated by activated cells originated from the naïve pool. Moreover, we argue that MP cell proliferation is driven by TCR and CD28 signaling whereas Th1 differentiation mediated by IL-2. Furthermore, our data indicate that such activation of MP and naïve CD4+ T lymphocytes contribute to development of multi-organ inflammation at early and later time points, respectively, after Treg ablation. Together our findings reveal that Tregs tonically inhibit early, spontaneous proliferation and Th1 differentiation of MP CD4+ T lymphocytes as well as late activation of naïve cells, thereby contributing to maintenance of T cell homeostasis.

The Effects of Gynecological Tumor Irradiation on the Immune System

Radiobiology has evolved from a mechanistic model based on DNA damage and response factors into a more complex model that includes effects on the immune system and the tumor microenvironment (TME). Irradiation has an immunomodulatory effect that can manifest as increased anti-tumor immunity or immunosuppression. Irradiation promotes an inflammatory microenvironment through the release of pro-inflammatory cytokines and endothelial damage, which recruit immune system cells to the irradiated area. Radiation-induced immunogenic cell death (ICD), characterized by the release of damage-associated molecular patterns (DAMPs) and tumor antigens, triggers an anti-tumor immune response of both innate and adaptive immunity. Anti-tumor immunity can manifest at a distance from the irradiated area, a phenomenon known as the abscopal effect (AE), which involves dendritic cells and CD8+ T cells. Irradiation also produces an immunosuppressive effect mediated by tumor-associated macrophages (TAMs) and regulatory T lymphocytes (Tregs), which counterbalances the immunostimulatory effect. In this work, we review the mechanisms involved in the radiation-induced immune response, which support the combined treatment of RT and immunotherapy, focusing, where possible, on gynecologic cancer.

Mesenchymal stem cell transplantation may be able to induce immunological tolerance in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a common, potentially fatal autoimmune disease involving a significant inflammatory response. SLE is characterised by failure of self-tolerance and activation of autoreactive lymphocytes, leading to persistent disease. Although current treatments achieve some improvement in patients, some SLE patients are refractory and others relapse after drug withdrawal. The toxicity of current drug regimens, with recurrent infections, together with ongoing inflammation, contribute significantly to the progressive decline in organ function. Therefore, the clinical management of SLE requires more effective and less toxic treatments, ideally inducing complete remission and self-tolerance. In this context, recently developed cell therapies based on mesenchymal stem cells (MSCs) represent a promising and safe strategy in SLE. MSCs inhibit the activation of B cells, prevent the differentiation of CD4⁺ T cells into autoreactive T cells, reprogram macrophages with anti-inflammatory effects and inhibit dendritic cells (DCs), limiting their activity as antigen-presenting cells. In addition, MSCs could induce antigen-specific tolerance by enhancing anergy processes in autoreactive cells - by inhibiting the maturation of antigen-presenting DCs, blocking the T cell receptor (TcR) pathway and secreting inhibitory molecules -, increasing apoptotic activity to eliminate them, and activating regulatory T cells (Tregs) to enhance their proliferation and induction of tolerogenic DCs. Thus, induction of self-tolerance leads to immune balance, keeping inflammation under control and reducing lupus flares.

Regulatory T cells and immune escape in HCC: understanding the tumor microenvironment and advancing CAR-T cell therapy

Liver cancer, which most commonly manifests as hepatocellular carcinoma (HCC), is the sixth most common cancer in the world. In HCC, the immune system plays a crucial role in the growth and proliferation of tumor cells. HCC achieve immune escape through the tumor microenvironment, which significantly promotes the development of this cancer. Here, this article introduces and summarizes the functions and effects of regulatory T cells (Tregs) in the tumor microenvironment, highlighting how Tregs inhibit and regulate the functions of immune and tumor cells, cytokines, ligands and receptors, etc, thereby promoting tumor immune escape. In addition, it discusses the mechanism of CAR-T therapy for HCC and elaborate on the relationship between CAR-T and Tregs.

PARP11 inhibition inactivates tumor-infiltrating regulatory T cells and improves the efficacy of immunotherapies

Tumor-infiltrating regulatory T cells (TI-Tregs) elicit immunosuppressive effects in the tumor microenvironment (TME) leading to accelerated tumor growth and resistance to immunotherapies against solid tumors. Here, we demonstrate that poly-(ADP-ribose)-polymerase-11 (PARP11) is an essential regulator of immunosuppressive activities of TI-Tregs. Expression of PARP11 correlates with TI-Treg cell numbers and poor responses to immune checkpoint blockade (ICB) in human patients with cancer. Tumor-derived factors including adenosine and prostaglandin E2 induce PARP11 in TI-Tregs. Knockout of PARP11 in the cells of the TME or treatment of tumor-bearing mice with selective PARP11 inhibitor ITK7 inactivates TI-Tregs and reinvigorates anti-tumor immune responses. Accordingly, ITK7 decelerates tumor growth and significantly increases the efficacy of anti-tumor immunotherapies including ICB and adoptive transfer of chimeric antigen receptor (CAR) T cells. These results characterize PARP11 as a key driver of TI-Treg activities and a major regulator of immunosuppressive TME and argue for targeting PARP11 to augment anti-cancer immunotherapies.

Advancements in nanomedicine delivery systems: unraveling immune regulation strategies for tumor immunotherapy

This review highlights the significant role of nanodrug delivery systems (NDDS) in enhancing the efficacy of tumor immunotherapy. Focusing on the integration of NDDS with immune regulation strategies, it explores their transformative impacts on the tumor microenvironment and immune response dynamics. Key advancements include the optimization of drug delivery through NDDS, targeting mechanisms like immune checkpoint blockade and modulating the immunosuppressive tumor environment. Despite the progress, challenges such as limited clinical efficacy and complex manufacturing processes persist. The review emphasizes the need for further research to optimize these systems, potentially revolutionizing cancer treatment by improving delivery efficiency, reducing toxicity and overcoming immune resistance.

Smoking increases risk of complication after musculoskeletal surgery: analysis of single immune parameter to predict complication risk

Smoking is the most significant and modifiable risk factor for a range of conditions, including cancer, cardiovascular and respiratory diseases. Furthermore, it significantly reduces bone mass and increases the risk of fragility fractures due to its detrimental effects on bone metabolism and regeneration. Moreover, smoking is a known cause of chronic systemic inflammation, leading to an imbalance of cytokines. Comprehending the pathological mechanisms that underlie cytokine production and its impact on post-surgical healing is essential to prevent post-surgical complications. The present study recruited a total of 1144 patients, including 897 patients, among them non-smokers (N = 413), current smokers (N = 201) and ex-smokers (N = 283). Human proteome profiler arrays were used to screen for smoking-dependent differences in the serum cytokine and protein profiles, after matching samples for age, gender, body mass index (BMI), alcohol use, and diabetes risk. Cytokines and immune checkpoint proteins such as CD28, B7-1, MIG, TGFβ2 and IL-1α/β were quantified by ELISA. Our study demonstrates a comprehensive understanding of the relationship between smoking, the development of complications, the systemic immune inflammation index (SII) and cytokine/protein levels. We found that a comparison of non-smokers, former smokers, and active smokers in our study cohort did not exhibit significantly altered cytokine and protein serum levels although other studies reported differences between smokers and non-smokers. We were unable to identify single blood circulating markers that could predict complications in smokers after trauma. However, we found the ratio of women to men to be inverted between non-smokers and active smokers resulting in a ratio of 0.62 in smokers. Furthermore, we demonstrate a higher complication rate, longer hospitalizations and elevated SII values among smokers, indicating an involvement of the immune system. See also the graphical abstract(Fig. 1).

Elucidating CTLA-4's role in tumor immunity: a comprehensive overview of targeted antibody therapies and clinical developments

Cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) emerges as a key single-chain transmembrane glycoprotein predominantly expressed in effector T cells and regulatory T cells. It plays a crucial role in tumor immunity by modulating T cell responses. Specifically, CTLA-4 dampens T cell activation and proliferation while bolstering the survival of regulatory T cell through its competitive interaction with B7 family molecules, thereby aiding tumor cells in eluding immune detection. Given CTLA-4's significant influence on tumor immune dynamics, an array of anti-CTLA-4 antibody therapeutics have been clinically developed to combat various malignancies, including melanoma, renal cell carcinoma, colorectal carcinoma, hepatocellular carcinoma, non-small cell lung carcinoma, and pleural mesothelioma, demonstrating notable clinical therapeutic effects. This paper aims to delve into CTLA-4's integral role in tumor immunity and to encapsulate the latest advancements in the clinical research of anti-CTLA-4 antibody.

The Complex Dysregulations of CD4 T Cell Subtypes in HIV Infection

Human immunodeficiency virus (HIV) infection remains an important global public health problem. About 40 million people are infected with HIV, and this infection caused about 630,000 deaths in 2022. The hallmark of HIV infection is the depletion of CD4+ T helper lymphocytes (Th cells). There are at least seven different Th subtypes, and not all are the main targets of HIV. Moreover, the effect of the virus in a specific subtype can be completely different from that of the others. Although the most compromised Th subtype in HIV infection is Th17, HIV can induce important dysregulations in other subtypes, such as follicular Th (Tfh) cells and regulatory Th cells (Treg cells or Tregs). Several studies have shown that HIV can induce an increase in the immunosuppressive activity of Tregs without causing a significant reduction in their numbers, at least in the early phase of infection. The increased activity of this Th subtype seems to play an important role in determining the immunodeficiency status of HIV-infected patients, and Tregs may represent a new target for innovative anti-HIV therapies, including the so-called "Kick and Kill" therapeutic method whose goal is the complete elimination of the virus and the healing of HIV infection. In this review, we report the most important findings on the effects of HIV on different CD4+ T cell subtypes, the molecular mechanisms by which the virus impairs the functions of these cells, and the implications for new anti-HIV therapeutic strategies.

Targeting cytotoxic lymphocyte antigen 4 (CTLA-4) in breast cancer

Breast cancer (BC) has a high mortality rate and is one of the most common malignancies in the world. Initially, BC was considered non-immunogenic, but a paradigm shift occurred with the discovery of tumor-infiltrating lymphocytes (TILs) and regulatory T cells (Tregs) in the BC tumor microenvironment. CTLA-4 (Cytotoxic T-lymphocyte-associated protein 4) immunotherapy has emerged as a treatment option for BC, but it has limitations, including suboptimal antitumor effects and toxicity. Research has demonstrated that anti-CTLA-4 combination therapies, such as Treg depletion, cancer vaccines, and modulation of the gut microbiome, are significantly more effective than CTLA-4 monoclonal antibody (mAB) monotherapy. Second-generation CTLA-4 antibodies are currently being developed to mitigate immune-related adverse events (irAEs) and augment antitumor efficacy. This review examines anti-CTLA-4 mAB in BC, both as monotherapy and in combination with other treatments, and sheds light on ongoing clinical trials, novel CTLA-4 therapeutic strategies, and potential utility of biomarkers in BC.

A review concerning the breast cancer-related tumour microenvironment

Breast cancer (BC) is currently the most common malignant tumour in women and one of the leading causes of their death around the world. New and increasingly personalised diagnostic and therapeutic tools have been introduced over the last few decades, along with significant advances regarding the study and knowledge related to BC. The tumour microenvironment (TME) refers to the tumour cell-associated cellular and molecular environment which can influence conditions affecting tumour development and progression. The TME is composed of immune cells, stromal cells, extracellular matrix (ECM) and signalling molecules secreted by these different cell types. Ever deeper understanding of TME composition changes during tumour development and progression will enable new and more innovative therapeutic strategies to become developed for targeting tumours during specific stages of its evolution. This review summarises the role of BC-related TME components and their influence on tumour progression and the development of resistance to therapy. In addition, an account on the modifications in BC-related TME components associated with therapy is given, and the completed or ongoing clinical trials related to this topic are presented.

Low-dose Interleukin-2 Therapy: Fine-tuning Treg in Solid Organ Transplantation?

Regulatory T cells (Treg), a subset of CD4 + T cells, are potent regulators of immune reactions, which have been shown to be a promising therapeutic alternative to toxic immunosuppressive drugs. Data support the utility of Treg in managing immunopathologies, including solid organ transplant rejection, graft-versus-host disease, and autoimmune disorders. Notably, reports suggest that interleukin-2 (IL-2) is critical to survival of Treg, which constitutively express high levels of CD25, that is, the IL-2 receptor α-chain, and are exquisitely sensitive to IL-2, even at very low concentrations in contrast to effector T cells, which only upregulate IL-2 receptor α-chain on activation. This has led to the notion of using low doses of exogenous IL-2 therapeutically to modulate the immune system, specifically Treg numbers and function. Here, we summarize developments of clinical experience with low-dose IL-2 (LD-IL-2) as a therapeutic agent. So far, no clinical data are available to support the therapeutic use of LD-IL-2 therapy in the solid organ transplant setting. For the latter, fine-tuning by biotechnological approaches may be needed because of the narrow therapeutic window and off-target effects of LD-IL-2 therapy and so to realize the therapeutic potential of this molecule.

Role of FoxP3+ Regulatory T Cells in Modulating Immune Responses to Adeno-Associated Virus Gene Therapy

Adeno-associated virus (AAV) gene therapy is making rapid strides owing to its wide range of therapeutic applications. However, development of serious immune responses to the capsid antigen or the therapeutic transgene product hinders its full clinical impact. Immune suppressive (IS) drug treatments have been used in various clinical trials to prevent the deleterious effects of cytotoxic T cells to the viral vector or transgene, although there is no consensus on the best treatment regimen, dosage, or schedule. Regulatory T cells (Tregs) are crucial for maintaining tolerance against self or nonself antigens. Of importance, Tregs also play an important role in dampening immune responses to AAV gene therapy, including tolerance induction to the transgene product. Approaches to harness the tolerogenic effect of Tregs include the use of selective IS drugs that expand existing Tregs, and skew activated conventional T cells into antigen-specific peripherally induced Tregs. In addition, Tregs can be expanded ex vivo and delivered as cellular therapy. Furthermore, receptor engineering can be used to increase the potency and specificity of Tregs allowing for suppression at lower doses and reducing the risk of disrupting protective immunity. Because immune-mediated toxicities to AAV vectors are a concern in the clinic, strategies that can enhance or preserve Treg function should be considered to improve both the safety and efficacy of AAV gene therapy.

Immune-related adverse events of antibody-based biological medicines in cancer therapy

Recombinant antibodies (Abs) are an integral modality for the treatment of multiple tumour malignancies. Since the Food and Drug Administration (FDA) approval of rituximab as the first monoclonal antibody (mAb) for cancer treatment, several mAbs and antibody (Ab)-based therapies have been approved for the treatment of solid tumour malignancies and other cancers. These Abs function by either blocking oncogenic pathways or angiogenesis, modulating immune response, or by delivering a conjugated drug. The use of Ab-based therapy in cancer patients who could benefit from the treatment, however, is still limited by associated toxicity profiles which may stem from biological features and processes related to target binding, alongside biochemical and/or biophysical characteristics of the therapeutic Ab. A significant immune-related adverse event (irAE) associated with Ab-based therapies is cytokine release syndrome (CRS), characterized by the development of fever, rash and even marked, life-threatening hypotension, and acute inflammation with secondary to systemic uncontrolled increase in a range of pro-inflammatory cytokines. Here, we review irAEs associated with specific classes of approved, Ab-based novel cancer immunotherapeutics, namely immune checkpoint (IC)-targeting Abs, bispecific Abs (BsAbs) and Ab-drug-conjugates (ADCs), highlighting the significance of harmonization in preclinical assay development for safety assessment of Ab-based biotherapeutics as an approach to support and refine clinical translation.

High percentage of bone marrow CD8+ tissue-resident-like memory T cells predicts inferior survival in patients with acute myeloid leukemia

Tissue-resident memory T (TRM) cells infiltrating solid tumors could influence tumor progression and the response to immune therapies. However, the proportion and prognostic value of TRM cells in the bone marrow (BM) of patients with acute myeloid leukemia (AML) are unclear. In this study, we used flow cytometry to assay the phenotype of 49 BM samples from patients newly diagnosed with AML (ND-AML). We found that the BM CD8+ effector memory (TEM) cells highly expressed CD69 (CD8+ TRM-like T cells), and their percentage was significantly increased in patients with ND-AML compared with that in healthy individuals (HI). The high percentage of CD8+ TRM-like subset was associated with poor overall survival in our ND-AML cohort. The Kaplan-Meier Plotter database verified a significantly reduced survival rate among patients with high expression of CD8+ TRM-like T cell characteristic genes (CD8A, CD69, and TOX), especially the M4 and M5 subtypes. Phenotypic analysis revealed that the BM CD8+ TRM-like subpopulation exhibited exhausted T cell characteristics, but its high expression of CD27 and CD28 and low expression of CD57 suggested its high proliferative potential. The single-cell proteogenomic dataset confirmed the existence of TRM-like CD8+ T cells in the BM of patients with AML and verified the high expression of immune checkpoints and costimulatory molecules. In conclusion, we found that the accumulation of BM CD8+ TRM-like cells could be an immune-related survival prediction marker for patients with AML.

The Potential Significance of the EMILIN3 Gene in Augmenting the Aggressiveness of Low-Grade Gliomas is Noteworthy

Purpose

Low-grade gliomas (LGG) are common brain tumors with high mortality rates. Cancer cell invasion is a significant factor in tumor metastasis. Novel biomarkers are urgently needed to predict LGG prognosis effectively.

Methods

The data for LGG were obtained from the Bioinformatics database. A consensus clustering analysis was performed to identify molecular subtypes linked with invasion in LGG. Differential expression analysis was performed to identify differentially expressed genes (DEGs) between the identified clusters. Enrichment analyses were then conducted to explore the function for DEGs. Prognostic signatures were placed, and their predictive power was assessed. Furthermore, the invasion-related prognostic signature was validated using the CGGA dataset. Subsequently, clinical specimens were procured in order to validate the expression levels of the distinct genes examined in this research, and to further explore the impact of these genes on the glioma cell line LN229 and HS-683.

Results

Two invasion-related molecular subtypes of LGG were identified, and we sifted 163 DEGs between them. The enrichment analyses indicated that DEGs are mainly related to pattern specification process. Subsequently, 10 signature genes (IGF2BP2, SRY, CHI3L1, IGF2BP3, MEOX2, ABCC3, HOXC4, OTP, METTL7B, and EMILIN3) were sifted out to construct a risk model. Besides, the survival (OS) in the high-risk group was lower. The performance of the risk model was verified. Furthermore, a highly reliable nomogram was generated. Cellular experiments revealed the ability to promote cell viability, value-addedness, migratory ability, invasive ability, and colony-forming ability of the glioma cell line LN229 and HS-683. The qRT-PCR analysis of clinical glioma samples showed that these 10 genes were expressed at higher levels in high-grade gliomas than in low-grade gliomas, suggesting that these genes are associated with poor prognosis of gliomas.

Conclusion

Our study sifted out ten invasion-related biomarkers of LGG, providing a reference for treatments and prognostic prediction in LGG.

Cholesterol efflux from C1QB-expressing macrophages is associated with resistance to chimeric antigen receptor T cell therapy in primary refractory diffuse large B cell lymphoma

Chimeric antigen receptor T (CAR-T) cell therapy has demonstrated promising efficacy in early trials for relapsed/refractory diffuse large B cell lymphoma (DLBCL). However, its efficacy in treating primary refractory DLBCL has not been comprehensively investigated, and the underlying resistance mechanisms remain unclear. Here, we report the outcomes of a phase I, open-label, single-arm clinical trial of relmacabtagene autoleucel (relma-cel), a CD19-targeted CAR-T cell product, with safety and efficacy as primary endpoints. Among the 12 enrolled patients, 8 experienced grade 4 hematologic toxicity of treatment-emergent adverse event. No grade ≥3 cytokine release syndrome or neurotoxicity occurred. Single-cell RNA sequencing revealed an increase proportion of C1QB-expressing macrophages in patients with progressive disease before CAR-T cell therapy. Cholesterol efflux from M2 macrophages was found to inhibit CAR-T cells cytotoxicity by inducing an immunosuppressive state in CD8+ T cells, leading to their exhaustion. Possible interactions between macrophages and CD8+ T cells, mediating lipid metabolism (AFR1-FAS), immune checkpoint activation, and T cell exhaustion (LGALS9-HAVCR2, CD86-CTLA4, and NECTIN2-TIGIT) were enhanced during disease progression. These findings suggest that cholesterol efflux from macrophages may trigger CD8+ T cell exhaustion, providing a rationale for metabolic reprogramming to counteract CAR-T treatment failure. Chinadrugtrials.org.cn identifier: CTR20200376.

Interruption of the intratumor CD8+ T cell:Treg crosstalk improves the efficacy of PD-1 immunotherapy

PD-1 blockade unleashes potent antitumor activity in CD8+ T cells but can also promote immunosuppressive T regulatory (Treg) cells, which may worsen the response to immunotherapy. Tumor-Treg inhibition is a promising strategy to improve the efficacy of checkpoint blockade immunotherapy; however, our understanding of the mechanisms supporting tumor-Tregs during PD-1 immunotherapy is incomplete. Here, we show that PD-1 blockade increases tumor-Tregs in mouse models of melanoma and metastatic melanoma patients. Mechanistically, Treg accumulation is not caused by Treg-intrinsic inhibition of PD-1 signaling but depends on an indirect effect of activated CD8+ T cells. CD8+ T cells produce IL-2 and colocalize with Tregs in mouse and human melanomas. IL-2 upregulates the anti-apoptotic protein ICOS on tumor-Tregs, promoting their accumulation. Inhibition of ICOS signaling before PD-1 immunotherapy improves control over immunogenic melanoma. Thus, interrupting the intratumor CD8+ T cell:Treg crosstalk represents a strategy to enhance the therapeutic efficacy of PD-1 immunotherapy.

Glutamine supplementation improves the activity and immunosuppressive action of induced regulatory T cells in vitro and in vivo

BACKGROUND

Glutamine is crucial for the activation and efficacy of T cells, and may play a role in regulating the immune environment. This study aimed to investigate the potential role of glutamine in the activation and proliferation of induced regulatory T cells (iTregs).

METHODS

CD4+CD45RA+T cells were sorted from peripheral blood mononuclear cells and cultured to analyze iTreg differentiation. Glutamine was then added to the culture system to evaluate the effects of glutamine on iTregs by determining oxidative phosphorylation (OXPHOS), apoptosis, and cytokine secretion. Additionally, a humanized murine graft-versus-host disease (GVHD) model was constructed to confirm the efficacy of glutamine-treated iTregs in vivo.

RESULTS

After being cultured in vitro, glutamine significantly enhanced the levels of Foxp3, CTLA-4, CD39, CD69, IL-10, TGF-β, and Ki67 (CTLA-4, IL-10, TGF-β are immunosuppressive markers of iTregs) compared with that of the control iTregs (P < 0.05). Furthermore, the growth curve showed that the proliferative ability of glutamine-treated iTregs was better than that of the control iTregs (P < 0.01). Compared with the control iTregs, glutamine supplementation significantly increased oxygen consumption rates and ATP production (P < 0.05), significantly downregulated Annexin V and Caspase 3, and upregulated BCL2 (P < 0.05). However, GPNA significantly reversed the effects of glutamine (P < 0.05). Finally, a xeno-GVHD mouse model was successfully established to confirm that glutamine-treated iTregs increased the mice survival rate, delayed weight loss, and alleviated colon injury.

CONCLUSION

Glutamine supplementation can improve the activity and immunosuppressive action of iTregs, and the possible mechanisms by which this occurs are related to cell proliferation, apoptosis, and OXPHOS.

Pathologic assessment of hepatocellular carcinoma in the era of immunotherapy: a narrative review

Background and Objective

Immune checkpoint inhibitor (ICI)-based therapy has achieved impressive success in various cancer types. Several ICIs have been unprecedentedly approved as the treatment regimens for advanced hepatocellular carcinoma (HCC) in recent decade. Meanwhile, numerous clinical trials are being performed to exploit more ICIs into initially unresectable HCC and postoperative HCC to expectantly induce adequate tumor downstaging for further resection or implement adjuvant treatment for relapse-free survival, respectively. In this review, we aim to summarize some pragmatic histomorphologic, immunohistochemical, and molecular pathologic parameters which promisingly indicate the response of neoadjuvant/conversion ICI-related therapy and predict the efficacy of adjuvant/therapeutic ICI-related therapy for HCC.

Methods

We searched PubMed using the terms hepatocellular carcinoma, immunotherapy, immune checkpoint inhibitor, immune checkpoint blockade, conversion therapy, neoadjuvant therapy, adjuvant therapy, biomarker, pathologic evaluation, pathologic assessment till February 2023.

Key Content and Findings

Although there is no consensus regarding the pathologic evaluation of relevant HCC specimens, it is encouraging that a few of studies have concentrated on this field, and moreover, the methods and parameters noted on other cancer types are also worthy of reference. For the pathologic assessment of HCC specimens underwent immunotherapy, a suitable sampling scheme, identifying immunotherapy-related pathologic response, and quantification of pathologic response rate should be emphasized. For the patients of HCC who are scheduled to receive immunotherapy, tumor-infiltrating lymphocyte, intratumoral tertiary lymphoid structure, programmed cell death ligand 1, Wnt/β-catenin, microsatellite instability and mismatch repair, tumor mutational burden and tumor neoantigen, as well as some other signaling pathways are the potential predictive biomarkers of treatment response of ICI.

Conclusions

The management of HCC in the era of immunotherapy arises a brand-new pathological challenge that is to provide an immunotherapy-related diagnostic report. Albeit many related researches are preclinical or insufficient, they may tremendously alter the immunotherapy strategy of HCC in future.

Treatment strategies and molecular mechanism of radiotherapy combined with immunotherapy in colorectal cancer

Radiotherapy (RT) remodels the tumor immune microenvironment (TIME) and modulates the immune response to indirectly destroy tumor cells, in addition to directly killing tumor cells. RT combined with immunotherapy may significantly enhance the efficacy of RT in colorectal cancer by modulating the microenvironment. However, the molecular mechanisms by which RT acts as an immunomodulator to modulate the immune microenvironment remain unclear. Further, the optimal modalities of RT combined with immunotherapy for the treatment of colorectal cancer, such as the time point of combining RT and immunization, the fractionation pattern and dosage of radiotherapy, and other methods to improve the efficacy, are also being explored parallelly. To address these aspects, in this review, we summarized the mechanisms by which RT modulates TIME and concluded the progress of RT combined with immunization in preclinical and clinical trials. Finally, we discussed heavy ion radiation therapy and the efficacy of prediction markers and other immune combination therapies. Overall, combining RT with immunotherapy to enhance antitumor effects will have a significant clinical implication and will help to facilitate individualized treatment modalities.

Crosstalk between efferocytic myeloid cells and T-cells and its relevance to atherosclerosis

The interplay between myeloid cells and T-lymphocytes is critical to the regulation of host defense and inflammation resolution. Dysregulation of this interaction can contribute to the development of chronic inflammatory diseases. Important among these diseases is atherosclerosis, which refers to focal lesions in the arterial intima driven by elevated apolipoprotein B-containing lipoproteins, notably low-density lipoprotein (LDL), and characterized by the formation of a plaque composed of inflammatory immune cells, a collection of dead cells and lipids called the necrotic core, and a fibrous cap. As the disease progresses, the necrotic core expands, and the fibrous cap becomes thin, which increases the risk of plaque rupture or erosion. Plaque rupture leads to a rapid thrombotic response that can give rise to heart attack, stroke, or sudden death. With marked lowering of circulating LDL, however, plaques become more stable and cardiac risk is lowered-a process known as atherosclerosis regression. A critical aspect of both atherosclerosis progression and regression is the crosstalk between innate (myeloid cells) and adaptive (T-lymphocytes) immune cells. Myeloid cells are specialized at clearing apoptotic cells by a process called efferocytosis, which is necessary for inflammation resolution. In advanced disease, efferocytosis is impaired, leading to secondary necrosis of apoptotic cells, inflammation, and, most importantly, defective tissue resolution. In regression, efferocytosis is reawakened aiding in inflammation resolution and plaque stabilization. Here, we will explore how efferocytosing myeloid cells could affect T-cell function and vice versa through antigen presentation, secreted factors, and cell-cell contacts and how this cellular crosstalk may contribute to the progression or regression of atherosclerosis.

Defining Human Regulatory T Cells beyond FOXP3: The Need to Combine Phenotype with Function

Regulatory T cells (Tregs) are essential to maintain immune homeostasis by promoting self-tolerance. Reduced Treg numbers or functionality can lead to a loss of tolerance, increasing the risk of developing autoimmune diseases. An overwhelming variety of human Tregs has been described, based on either specific phenotype, tissue compartment, or pathological condition, yet the bulk of the literature only addresses CD25-positive and CD127-negative cells, coined by naturally occurring Tregs (nTregs), most of which express the transcription factor Forkhead box protein 3 (FOXP3). While the discovery of FOXP3 was seminal to understanding the origin and biology of nTregs, there is evidence in humans that not all T cells expressing FOXP3 are regulatory, and that not all Tregs express FOXP3. Namely, the activation of human T cells induces the transient expression of FOXP3, irrespective of whether they are regulatory or inflammatory effectors, while some induced T cells that may be broadly defined as Tregs (e.g., Tr1 cells) typically lack demethylation and do not express FOXP3. Furthermore, it is unknown whether and how many nTregs exist without FOXP3 expression. Several other candidate regulatory molecules, such as GITR, Lag-3, GARP, GPA33, Helios, and Neuropilin, have been identified but subsequently discarded as Treg-specific markers. Multiparametric analyses have uncovered a plethora of Treg phenotypes, and neither single markers nor combinations thereof can define all and only Tregs. To date, only the functional capacity to inhibit immune responses defines a Treg and distinguishes Tregs from inflammatory T cells (Teffs) in humans. This review revisits current knowledge of the Treg universe with respect to their heterogeneity in phenotype and function. We propose that it is unavoidable to characterize human Tregs by their phenotype in combination with their function, since phenotype alone does not unambiguously define Tregs. There is an unmet need to align the expression of specific markers or combinations thereof with a particular suppressive function to coin functional Treg entities and categorize Treg diversity.

Endolysosomal transient receptor potential mucolipins and two-pore channels: implications for cancer immunity

Past research has identified that cancer cells sustain several cancer hallmarks by impairing function of the endolysosomal system (ES). Thus, maintaining the functional integrity of endolysosomes is crucial, which heavily relies on two key protein families: soluble hydrolases and endolysosomal membrane proteins. Particularly members of the TPC (two-pore channel) and TRPML (transient receptor potential mucolipins) families have emerged as essential regulators of ES function as a potential target in cancer therapy. Targeting TPCs and TRPMLs has demonstrated significant impact on multiple cancer hallmarks, including proliferation, growth, migration, and angiogenesis both in vitro and in vivo. Notably, endosomes and lysosomes also actively participate in various immune regulatory mechanisms, such as phagocytosis, antigen presentation, and the release of proinflammatory mediators. Yet, knowledge about the role of TPCs and TRPMLs in immunity is scarce. This prompts a discussion regarding the potential role of endolysosomal ion channels in aiding cancers to evade immune surveillance and destruction. Specifically, understanding the interplay between endolysosomal ion channels and cancer immunity becomes crucial. Our review aims to comprehensively explore the current knowledge surrounding the roles of TPCs and TRPMLs in immunity, whilst emphasizing the critical need to elucidate their specific contributions to cancer immunity by pointing out current research gaps that should be addressed.

Immunomodulatory Precision: A Narrative Review Exploring the Critical Role of Immune Checkpoint Inhibitors in Cancer Treatment

An immune checkpoint is a signaling pathway that regulates the recognition of antigens by T-cell receptors (TCRs) during an immune response. These checkpoints play a pivotal role in suppressing excessive immune responses and maintaining immune homeostasis against viral or microbial infections. There are several FDA-approved immune checkpoint inhibitors (ICIs), including ipilimumab, pembrolizumab, and avelumab. These ICIs target cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), programmed cell death protein 1 (PD-1), and programmed death ligand 1 (PD-L1). Furthermore, ongoing efforts are focused on developing new ICIs with emerging potential. In comparison to conventional treatments, ICIs offer the advantages of reduced side effects and durable responses. There is growing interest in the potential of combining different ICIs with chemotherapy, radiation therapy, or targeted therapies. This article comprehensively reviews the classification, mechanism of action, application, and combination strategies of ICIs in various cancers and discusses their current limitations. Our objective is to contribute to the future development of more effective anticancer drugs targeting immune checkpoints.

Critical role of the gut microbiota in immune responses and cancer immunotherapy

The gut microbiota plays a critical role in the progression of human diseases, especially cancer. In recent decades, there has been accumulating evidence of the connections between the gut microbiota and cancer immunotherapy. Therefore, understanding the functional role of the gut microbiota in regulating immune responses to cancer immunotherapy is crucial for developing precision medicine. In this review, we extract insights from state-of-the-art research to decipher the complicated crosstalk among the gut microbiota, the systemic immune system, and immunotherapy in the context of cancer. Additionally, as the gut microbiota can account for immune-related adverse events, we discuss potential interventions to minimize these adverse effects and discuss the clinical application of five microbiota-targeted strategies that precisely increase the efficacy of cancer immunotherapy. Finally, as the gut microbiota holds promising potential as a target for precision cancer immunotherapeutics, we summarize current challenges and provide a general outlook on future directions in this field.

Regulation of Treg cells by cytokine signaling and co-stimulatory molecules

CD4+CD25+Foxp3+ regulatory T cells (Tregs), a vital component of the immune system, are responsible for maintaining immune homeostasis and preventing excessive immune responses. This review explores the signaling pathways of the cytokines that regulate Treg cells, including transforming growth factor beta (TGF-β), interleukin (IL)-2, IL-10, and IL-35, which foster the differentiation and enhance the immunosuppressive capabilities of Tregs. It also examines how, conversely, signals mediated by IL-6 and tumor necrosis factor -alpha (TNF-α) can undermine Treg suppressive functions or even drive their reprogramming into effector T cells. The B7 family comprises indispensable co-stimulators for T cell activation. Among its members, this review focuses on the capacity of CTLA-4 and PD-1 to regulate the differentiation, function, and survival of Tregs. As Tregs play an essential role in maintaining immune homeostasis, their dysfunction contributes to the pathogenesis of autoimmune diseases. This review delves into the potential of employing Treg-based immunotherapy for the treatment of autoimmune diseases, transplant rejection, and cancer. By shedding light on these topics, this article aims to enhance our understanding of the regulation of Tregs by cytokines and their therapeutic potential for various pathological conditions.

Regulatory T cells as crucial trigger and potential target for hyperprogressive disease subsequent to PD-1/PD-L1 blockade for cancer treatment

PD-1/PD-L1 blockade therapy has brought great success to cancer treatment. Nevertheless, limited beneficiary populations and even hyperprogressive disease (HPD) greatly constrain the application of PD-1/PD-L1 inhibitors in clinical treatment. HPD is a special pattern of disease progression with rapid tumor growth and even serious consequences of patient death, which requires urgent attention. Among the many predisposing causes of HPD, regulatory T cells (Tregs) are suspected because they are amplified in cases of HPD. Tregs express PD-1 thus PD-1/PD-L1 blockade therapy may have an impact on Tregs which leads to HPD. Tregs are a subset of CD4+ T cells expressing FoxP3 and play critical roles in suppressing immunity. Tregs migrate toward tumors in the presence of chemokines to suppress antitumor immune responses, causing cancer cells to grow and proliferate. Studies have shown that deleting Tregs could enhance the efficacy of PD-1/PD-L1 blockade therapy and reduce the occurrence of HPD. This suggests that immunotherapy combined with Treg depletion may be an effective means of avoiding HPD. In this review, we summarized the immunosuppressive-related functions of Tregs in antitumor therapy and focused on advances in therapy combining Tregs depletion with PD-1/PD-L1 blockade in clinical studies. Moreover, we provided an outlook on Treg-targeted HPD early warning for PD-1/PD-L1 blockade therapy.

The immunopathogenesis of sarcoidosis

Sarcoidosis is a granulomatous multiorgan disease, thought to result from exposure to yet unidentified antigens in genetically susceptible individuals. The exaggerated inflammatory response that leads to granuloma formation is highly complex and involves the innate and adaptive immune system. Consecutive immunological studies using advanced technology have increased our understanding of aberrantly activated immune cells, mediators and pathways that influence the formation, maintenance and resolution of granulomas. Over the years, it has become increasingly clear that disease immunopathogenesis can only be understood if the clinical heterogeneity of sarcoidosis is taken into consideration, along with the distribution of immune cells in peripheral blood and involved organs. Most studies offer an immunological snapshot during disease course, while the cellular composition of both the circulation and tissue microenvironment may change over time. Despite these challenges, novel insights on the role of the immune system are continuously published, thus bringing the field forward. This review highlights current knowledge on the innate and adaptive immune responses involved in sarcoidosis pathogenesis, as well as the pathways involved in non-resolving disease and fibrosis development. Additionally, we describe proposed immunological mechanisms responsible for drug-induced sarcoid like reactions. Although many aspects of disease immunopathogenesis remain to be unraveled, the identification of crucial immune reactions in sarcoidosis may help identify new treatment targets. We therefore also discuss potential therapies and future strategies based on the latest immunological findings.

Regulatory T cell-mediated immunosuppression orchestrated by cancer: towards an immuno-genomic paradigm for precision medicine

Accumulating evidence indicates that aberrant signalling stemming from genetic abnormalities in cancer cells has a fundamental role in their evasion of antitumour immunity. Immune escape mechanisms include enhanced expression of immunosuppressive molecules, such as immune-checkpoint proteins, and the accumulation of immunosuppressive cells, including regulatory T (Treg) cells, in the tumour microenvironment. Therefore, Treg cells are key targets for cancer immunotherapy. Given that therapies targeting molecules predominantly expressed by Treg cells, such as CD25 or GITR, have thus far had limited antitumour efficacy, elucidating how certain characteristics of cancer, particularly genetic abnormalities, influence Treg cells is necessary to develop novel immunotherapeutic strategies. Hence, Treg cell-targeted strategies based on the particular characteristics of cancer in each patient, such as the combination of immune-checkpoint inhibitors with molecularly targeted agents that disrupt the immunosuppressive networks mediating Treg cell recruitment and/or activation, could become a new paradigm of cancer therapy. In this Review, we discuss new insights on the mechanisms by which cancers generate immunosuppressive networks that attenuate antitumour immunity and how these networks confer resistance to cancer immunotherapy, with a focus on Treg cells. These insights lead us to propose the concept of 'immuno-genomic precision medicine' based on specific characteristics of cancer, especially genetic profiles, that correlate with particular mechanisms of tumour immune escape and might, therefore, inform the optimal choice of immunotherapy for individual patients.

Current Landscape of Cancer Immunotherapy: Harnessing the Immune Arsenal to Overcome Immune Evasion

Cancer immune evasion represents a leading hallmark of cancer, posing a significant obstacle to the development of successful anticancer therapies. However, the landscape of cancer treatment has significantly evolved, transitioning into the era of immunotherapy from conventional methods such as surgical resection, radiotherapy, chemotherapy, and targeted drug therapy. Immunotherapy has emerged as a pivotal component in cancer treatment, harnessing the body's immune system to combat cancer and offering improved prognostic outcomes for numerous patients. The remarkable success of immunotherapy has spurred significant efforts to enhance the clinical efficacy of existing agents and strategies. Several immunotherapeutic approaches have received approval for targeted cancer treatments, while others are currently in preclinical and clinical trials. This review explores recent progress in unraveling the mechanisms of cancer immune evasion and evaluates the clinical effectiveness of diverse immunotherapy strategies, including cancer vaccines, adoptive cell therapy, and antibody-based treatments. It encompasses both established treatments and those currently under investigation, providing a comprehensive overview of efforts to combat cancer through immunological approaches. Additionally, the article emphasizes the current developments, limitations, and challenges in cancer immunotherapy. Furthermore, by integrating analyses of cancer immunotherapy resistance mechanisms and exploring combination strategies and personalized approaches, it offers valuable insights crucial for the development of novel anticancer immunotherapeutic strategies.

Spontaneous immunological activities in the target tissue of vitiligo-prone Smyth and vitiligo-susceptible Brown lines of chicken

Introduction

Vitiligo is an acquired de-pigmentation disorder characterized by the post-natal loss of epidermal melanocytes (pigment-producing cells) resulting in the appearance of white patches in the skin. The Smyth chicken is the only model for vitiligo that shares all the characteristics of the human condition including: spontaneous post-natal loss of epidermal melanocytes, interactions between genetic, environmental and immunological factors, and associations with other autoimmune diseases. In addition, an avian model for vitiligo has the added benefit of an easily accessible target tissue (a growing feather) that allows for the repeated sampling of an individual and thus the continuous monitoring of local immune responses over time.

Methods

Using a combination of flow cytometry and gene expression analyses, we sought to gain a comprehensive understanding of the initiating events leading to expression of vitiligo in growing feathers by monitoring the infiltration of leukocytes and concurrent immunological activities in the target tissue beginning prior to visual onset and continuing throughout disease development.

Results

Here, we document a sequence of immunologically significant events, including characteristic rises in infiltrating B and αβ T cells as well as evidence of active leukocyte recruitment and cell-mediated immune activities (CCL19, IFNG, GZMA) leading up to visual vitiligo onset. Examination of growing feathers from vitiligo-susceptible Brown line chickens revealed anti-inflammatory immune activities which may be responsible for preventing vitiligo (IL10, CTLA4, FOXP3). Furthermore, we detected positive correlations between infiltrating T cells and changes in their T cell receptor diversity supporting a T cell-specific immune response.

Conclusion

Collectively, these results further support the notion of cell-mediated immune destruction of epidermal melanocytes in the pulp of growing feathers and open new avenues of study in the vitiligo-prone Smyth and vitiligo-susceptible Brown line chickens.

Receptor transfer between immune cells by autoantibody-enhanced, CD32-driven trogocytosis is hijacked by HIV-1 to infect resting CD4 T cells

Immune cell phenotyping frequently detects lineage-unrelated receptors. Here, we report that surface receptors can be transferred from primary macrophages to CD4 T cells and identify the Fcγ receptor CD32 as driver and cargo of this trogocytotic transfer. Filamentous CD32+ nanoprotrusions deposit distinct plasma membrane patches onto target T cells. Transferred receptors confer cell migration and adhesion properties, and macrophage-derived membrane patches render resting CD4 T cells susceptible to infection by serving as hotspots for HIV-1 binding. Antibodies that recognize T cell epitopes enhance CD32-mediated trogocytosis. Such autoreactive anti-HIV-1 envelope antibodies can be found in the blood of HIV-1 patients and, consistently, the percentage of CD32+ CD4 T cells is increased in their blood. This CD32-mediated, antigen-independent cell communication mode transiently expands the receptor repertoire and functionality of immune cells. HIV-1 hijacks this mechanism by triggering the generation of trogocytosis-promoting autoantibodies to gain access to immune cells critical to its persistence.

Immune-Related Adverse Events Due to Cancer Immunotherapy: Immune Mechanisms and Clinical Manifestations

The landscape of cancer treatment has undergone a significant transformation with the introduction of Immune Checkpoint Inhibitors (ICIs). Patients undergoing these treatments often report prolonged clinical and radiological responses, albeit with a potential risk of developing immune-related adverse events (irAEs). Here, we reviewed and discussed the mechanisms of action of ICIs and their pivotal role in regulating the immune system to enhance the anti-tumor immune response. We scrutinized the intricate pathogenic mechanisms responsible for irAEs, arising from the evasion of self-tolerance checkpoints due to drug-induced immune modulation. We also summarized the main clinical manifestations due to irAEs categorized by organ types, detailing their incidence and associated risk factors. The occurrence of irAEs is more frequent when ICIs are combined; with neurological, cardiovascular, hematological, and rheumatic irAEs more commonly linked to PD1/PD-L1 inhibitors and cutaneous and gastrointestinal irAEs more prevalent with CTLA4 inhibitors. Due to the often-nonspecific signs and symptoms, the diagnosis of irAEs (especially for those rare ones) can be challenging. The differential with primary autoimmune disorders becomes sometimes intricate, given the clinical and pathophysiological similarities. In conclusion, considering the escalating use of ICIs, this area of research necessitates additional clinical studies and practical insights, especially the development of biomarkers for predicting immune toxicities. In addition, there is a need for heightened education for both clinicians and patients to enhance understanding and awareness.