Engineered Treg cells: The heir to the throne of immunotherapy

Exploiting regulatory T cells (Tregs): Cutting-edge therapy for autoimmune diseases

Regulatory T cells (Tregs) are a specialized subset of suppressive T cells that are essential for maintaining self-tolerance, regulating effector T cells, managing microbial infections, preventing tumors, allergies, and autoimmune disorders, and facilitating allograft transplantation. Disruptions in Treg function or abundance contribute to an imbalance between pathogenic and protective immune cells in autoimmune diseases. Recently, one promising treatment strategy to restore immune balance involves the selective expansion or manipulation of Tregs using low-dose IL-2 therapy, adoptive Treg cell transfer, and chimeric antigen receptor (CAR)-Treg approaches. Tregs have been shown in an increasing number of research studies to prevent or even treat a variety of disorders, such as tumors, autoimmune and allergic diseases, transplant rejection, and graft-versus-host disease. A thorough comprehension of Treg function is anticipated to provide clear prospects for effective Treg immunotherapy in the treatment of a wide range of diseases. This review provides an overview of Tregs biology, including their functions, suppressive mechanisms, phenotypic markers, as well as their involvement in disease settings. Furthermore, we discuss the therapeutic potential of different Treg subpopulations and their translational applications in the treatment of autoimmune diseases.

Tolerogenic Therapies in Cardiac Transplantation

Heart transplantation remains the gold-standard treatment for end-stage heart failure, yet long-term graft survival is hindered by chronic rejection and the morbidity and mortality caused by lifelong immunosuppression. While advances in medical and device-based therapies have reduced the overall need for transplantation, patients who ultimately require a transplant often present with more advanced disease and comorbidities. Recent advances in tolerance-inducing strategies offer promising avenues to improve allograft acceptance, while minimizing immunosuppressive toxicity. This review explores novel approaches aiming to achieve long-term immunological tolerance, including co-stimulation blockade, mixed chimerism, regulatory T-cell (Treg) therapies, thymic transplantation, and double-organ transplantation. These strategies seek to promote donor-specific unresponsiveness and mitigate chronic rejection. Additionally, expanding the donor pool remains a critical challenge in addressing organ shortages. Innovations such as ABO-incompatible heart transplantation are revolutionizing the field by increasing donor availability and accessibility. In this article, we discuss the mechanistic basis, clinical advancements, and challenges of these approaches, highlighting their potential to transform the future of heart transplantation with emphasis on clinical translation.

Therapeutic application of regulatory T cell in osteoarthritis

Regulatory T cells (Tregs) are the specific T cell population that suppress inflammatory immunity. Independent of their inhibitory activities, Tregs exhibit unique capacity to repair tissue damage. Rapid progresses are made in the processing and engineering of Tregs for clinical applications. Tregs have been used in the treatment of autoimmune diseases, transplantation rejection and graft-versus-host disease. Osteoarthritis is one of the major diseases that affect at least 600 million people worldwide. Osteoarthritis is characterized by physical erosion of cartilage, accompanied with chronic and low-grade inflammation. Tregs possess abilities to increase osteoclast differentiation and bone resorption, repair bone physical damage, and increase bone mass. Tregs are therefore candidate therapeutics for osteoarthritis for both inflammation resolution and tissue repairing. In this review, we will summarize the recent development in using Tregs in immunotherapy, and the potential of using Tregs in osteoarthritis.

Synthetic receptor-based cell therapies for autoimmune diseases: an update

Increasing frequency of autoimmune diseases is one of the major problems in modern societies. Despite the introduction of new therapeutic agents for autoimmunity over the past several decades, more progress is needed. Synthetic receptor-based cell therapies are being adopted as an option for treating autoimmune diseases from the field of oncology. Currently evaluated strategies can be summarized into two approaches. The first one is the elimination of autoreactive cells by targeting them, for example, with CAR-T or CAAR-T cells. The second is based on rebalancing the proinflammatory milieu with engineered immunosuppressive cells, for example, CAR-Treg. Both approaches can be supplemented with the use of synthetic systems such as Split-CAR, SynNotch, MESA, GEMS, and SNIPR, or prospective off-the-shelf approaches, for example, in situ use of the in vitro transcribed mRNA, ultimately allowing for enhanced efficacy and safety. The primary goal of our review is to provide some perspective on both strategies in basic, translational, and clinical studies with all their advantages and disadvantages to allow for informed future design of adoptive cell therapies for autoimmune diseases.

Longitudinal Variations in Th and Treg Cells Before and After Percutaneous Coronary Intervention, and Their Intercorrelations and Prognostic Value in Acute Syndrome Patients

T helper (Th) and regulatory T (Treg) cells regulate atherosclerosis, plaque, inflammation to involve in acute coronary syndrome (ACS). The current study aimed to investigate the clinical implications of Th and Treg cells in ACS patients receiving percutaneous coronary intervention (PCI). Blood Th1, Th2, Th17 and Treg cells were detected in 160 ACS patients before PCI, after PCI, at 1 month (M). Short physical performance battery (SPPB) at M1/M3 and major adverse cardiac event (MACE) during follow-ups were evaluated. Th1 and Th17 both showed upward trends during PCI, then greatly declined at M1 (P < 0.001). Th2 exhibited an upward trend during PCI but decreased slightly at M1 (P < 0.001). Treg remained stable during PCI but elevated at M1 (P < 0.001). Moreover, a positive correlation between Th1 and Th17, a negative correlation between Th17 and Treg, were discovered at several timepoints (most P < 0.050). Interestingly, the receiver operating curve (ROC) analyses revealed that Th1 [area under curve (AUC) between 0.633-0.645] and Th17 (AUC between 0.626-0.699) exhibited values estimating SPPB score <= 6 points at M1 or M3 to some extent. Importantly, Th1 (AUC between 0.708-0.710), Th17 (AUC between 0.694-0.783), and Treg (AUC between 0.706-0.729) predicted MACE risk. Multivariate models involving Th and Treg cells along with other characteristics revealed acceptable values estimating SPPB score <= 6 points at M1 or M3 (AUC between 0.690-0.813), and good values predicting MACE risk (AUC between 0.830-0.971). Dynamic variations in Th and Treg cells can predict the prognosis of ACS patients receiving PCI.

Improving regulatory T cell-based therapy: insights into post-translational modification regulation

Regulatory T (Treg) cells are pivotal for maintaining immune homeostasis and play essential roles in various diseases, such as autoimmune diseases, graft-versus-host disease (GVHD), tumors, and infectious diseases. Treg cells exert suppressive function via distinct mechanisms, including inhibitory cytokines, granzyme or perforin-mediated cytolysis, metabolic disruption, and suppression of dendritic cells. Forkhead Box P3 (FOXP3), the characteristic transcription factor, is essential for Treg cell function and plasticity. Cumulative evidence has demonstrated that FOXP3 activity and Treg cell function are modulated by a variety of post-translational modifications (PTMs), including ubiquitination, acetylation, phosphorylation, methylation, glycosylation, poly(ADP-ribosyl)ation, and uncharacterized modifications. This review describes Treg cell suppressive mechanisms and summarizes the current evidence on PTM regulation of FOXP3 and Treg cell function. Understanding the regulatory role of PTMs in Treg cell plasticity and function will be helpful in designing therapeutic strategies for autoimmune diseases, GVHD, tumors, and infectious diseases.

Infiltrating T lymphocytes and tumor microenvironment within cholangiocarcinoma: immune heterogeneity, intercellular communication, immune checkpoints

Cholangiocarcinoma is the second most common primary liver cancer, and its global incidence has increased in recent years. Radical surgical resection and systemic chemotherapy have traditionally been the standard treatment options. However, the complexity of cholangiocarcinoma subtypes often presents a challenge for early diagnosis. Additionally, high recurrence rates following radical treatment and resistance to late-stage chemotherapy limit the benefits for patients. Immunotherapy has emerged as an effective strategy for treating various types of cancer, and has shown efficacy when combined with chemotherapy for cholangiocarcinoma. Current immunotherapies targeting cholangiocarcinoma have predominantly focused on T lymphocytes within the tumor microenvironment, and new immunotherapies have yielded unsatisfactory results in clinical trials. Therefore, it is essential to achieve a comprehensive understanding of the unique tumor microenvironment of cholangiocarcinoma and the pivotal role of T lymphocytes within it. In this review, we describe the heterogeneous immune landscape and intercellular communication in cholangiocarcinoma and summarize the specific distribution of T lymphocytes. Finally, we review potential immune checkpoints in cholangiocarcinoma.

Mini-Review: Tregs as a Tool for Therapy-Obvious and Non-Obvious Challenges and Solutions

Tregs have the potential to be utilized as a novel therapeutic agent for the treatment of various chronic diseases, including diabetes, Alzheimer's disease, asthma, and rheumatoid arthritis. One of the challenges associated with developing a therapeutic product based on Tregs is the non-selectivity of polyclonal cells. A potential solution to this issue is a generation of antigen-specific CAR-Tregs. Other challenges associated with developing a therapeutic product based on Tregs include the phenotypic instability of these cells in an inflammatory microenvironment, discrepancies between engineered Treg-like cells and natural Tregs, and the expression of dysfunctional isoforms of Treg marker genes. This review presents a summary of proposed strategies for addressing these challenges.

Intestinal flora and bile acid interactions impact the progression of diabetic kidney disease

In recent years, with the rapid development of omics technologies, researchers have shown that interactions between the intestinal flora and bile acids are closely related to the progression of diabetic kidney disease (DKD). By regulating bile acid metabolism and receptor expression, the intestinal flora affects host metabolism, impacts the immune system, and exacerbates kidney injury in DKD patients. To explore interactions among the gut flora, bile acids and DKD, as well as the related mechanisms, in depth, in this paper, we review the existing literature on correlations among the gut flora, bile acids and DKD. This review also summarizes the efficacy of bile acids and their receptors as well as traditional Chinese medicines in the treatment of DKD and highlights the unique advantages of bile acid receptors in DKD treatment. This paper is expected to reveal a new and important potential strategy for the clinical treatment of DKD.

Regulatory T lymphocytes as a treatment method for rheumatoid arthritis - Superiority of allogeneic to autologous cells

Cellular therapies utilizing regulatory T cells (Tregs) have flourished in the autoimmunity space as a new pillar of medicine. These cells have shown a great promise in the treatment of such devastating conditions as type 1 diabetes mellitus (T1DM), systemic lupus erythematosus (SLE) and graft versus host disease (GVHD). Novel treatment protocols, which utilize Tregs-mediated suppressive mechanisms, are based on the two main strategies: administration of immunomodulatory factors affecting Tregs or adoptive cell transfer (ACT). ACT involves extraction, in vitro expansion and subsequent administration of Tregs that could be either of autologous or allogeneic origin. Rheumatoid arthritis (RA) is another autoimmune candidate where this treatment approach is being considered. RA remains an especially challenging adversary since it is one of the most frequent and debilitating conditions among all autoaggressive disorders. Noteworthy, Tregs circulating in RA patients' blood have been proven defective and unable to suppress inflammation and joint destruction. With this knowledge, adoptive transfer of compromised autologous Tregs in the fledgling clinical trials involving RA patients should be reconsidered. In this article we hypothesize that incorporation of healthy donor allogeneic Tregs may provide more lucid and beneficial results.

Clinical Application of Adenovirus (AdV): A Comprehensive Review

Adenoviruses are non-enveloped DNA viruses that cause a wide range of symptoms, from mild infections to life-threatening diseases in a broad range of hosts. Due to the unique characteristics of these viruses, they have also become a vehicle for gene-transfer and cancer therapeutic instruments. Adenovirus vectors can be used in gene therapy by modifying wild-type viruses to render them replication-defective. This makes it possible to swap out particular viral genes for segments that carry therapeutic genes and to employ the resultant vector as a means of delivering genes to specified tissues. In this review, we outline the progressive development of adenovirus vectors, exploring their characteristics, genetic modifications, and range of uses in clinical and preclinical settings. A significant emphasis is placed on their crucial role in advancing gene therapy, cancer therapy, immunotherapy, and the latest breakthroughs in vaccine development for various diseases.

Immune modulation in transplant medicine: a comprehensive review of cell therapy applications and future directions

Balancing the immune response after solid organ transplantation (SOT) and vascularized composite allotransplantation (VCA) remains an ongoing clinical challenge. While immunosuppressants can effectively reduce acute rejection rates following transplant surgery, some patients still experience recurrent acute rejection episodes, which in turn may progress to chronic rejection. Furthermore, these immunosuppressive regimens are associated with an increased risk of malignancies and metabolic disorders. Despite significant advancements in the field, these IS related side effects persist as clinical hurdles, emphasizing the need for innovative therapeutic strategies to improve transplant survival and longevity. Cellular therapy, a novel therapeutic approach, has emerged as a potential pathway to promote immune tolerance while minimizing systemic side-effects of standard IS regiments. Various cell types, including chimeric antigen receptor T cells (CAR-T), mesenchymal stromal cells (MSCs), regulatory myeloid cells (RMCs) and regulatory T cells (Tregs), offer unique immunomodulatory properties that may help achieve improved outcomes in transplant patients. This review aims to elucidate the role of cellular therapies, particularly MSCs, T cells, Tregs, RMCs, macrophages, and dendritic cells in SOT and VCA. We explore the immunological features of each cell type, their capacity for immune regulation, and the prospective advantages and obstacles linked to their application in transplant patients. An in-depth outline of the current state of the technology may help SOT and VCA providers refine their perioperative treatment strategies while laying the foundation for further trials that investigate cellular therapeutics in transplantation surgery.

Potential anti-tumor effects of regulatory T cells in the tumor microenvironment: a review

Regulatory T cells (Tregs) expressing the transcription factor FoxP3 are essential for maintaining immunological balance and are a significant component of the immunosuppressive tumor microenvironment (TME). Single-cell RNA sequencing (ScRNA-seq) technology has shown that Tregs exhibit significant plasticity and functional diversity in various tumors within the TME. This results in Tregs playing a dual role in the TME, which is not always centered around supporting tumor progression as typically believed. Abundant data confirms the anti-tumor activities of Tregs and their correlation with enhanced patient prognosis in specific types of malignancies. In this review, we summarize the potential anti-tumor actions of Tregs, including suppressing tumor-promoting inflammatory responses and boosting anti-tumor immunity. In addition, this study outlines the spatial and temporal variations in Tregs function to emphasize that their predictive significance in malignancies may change. It is essential to comprehend the functional diversity and potential anti-tumor effects of Tregs to improve tumor therapy strategies.

Chimeric antigen receptor Treg therapy in transplantation

In the quest for more precise and effective organ transplantation therapies, chimeric antigen receptor (CAR) regulatory T cell (Treg) therapies represent a potential cutting-edge advance. This review comprehensively analyses CAR Tregs and how they may address important drawbacks of polyclonal Tregs and conventional immunosuppressants. We examine a growing body of preclinical findings of CAR Treg therapy in transplantation, discuss CAR Treg design specifics, and explore established and attractive new targets in transplantation. In addition, we explore present impediments where future studies will be necessary to determine the efficacy of CAR Tregs in reshaping alloimmune responses and transplant microenvironments to reduce reliance on chemical immunosuppressants. Overall, ongoing studies and trials are crucial for understanding the full scope of CAR Treg therapy in transplantation.

Challenges and opportunities in the islet transplantation microenvironment: a comprehensive summary of inflammatory cytokine, immune cells, and vascular endothelial cells

It is now understood that islet transplantation serves as a β-cell replacement therapy for type 1 diabetes. Many factors impact the survival of transplanted islets, especially those related to the microenvironment. This review explored microenvironmental components, including vascular endothelial cells, inflammatory cytokines, and immune cells, and their profound effects on post-islet transplantation survival rates. Furthermore, it revealed therapeutic strategies aimed at targeting these elements. Current evidence suggests that vascular endothelial cells are pivotal in facilitating vascularization and nutrient supply and establishing a new microcirculation network for transplanted islets. Consequently, preserving the functionality of vascular endothelial cells emerges as a crucial strategy to enhance the survival of islet transplantation. Release of cytokines will lead to activation of immune cells and production and release of further cytokines. While immune cells hold undeniable significance in regulating immune responses, their activation can result in rejection reactions. Thus, establishing immunological tolerance within the recipient's body is essential for sustaining graft functionality. Indeed, future research endeavors should be directed toward developing precise strategies for modulating the microenvironment to achieve higher survival rates and more sustained transplantation outcomes. While acknowledging certain limitations inherent to this review, it provides valuable insights that can guide further exploration in the field of islet transplantation. In conclusion, the microenvironment plays a paramount role in islet transplantation. Importantly, we discuss novel perspectives that could lead to broader clinical applications and improved patient outcomes in islet transplantation.

Why Treg should be the focus of cancer immunotherapy: The latest thought

Regulatory T cells are a subgroup of T cells with immunomodulatory functions. Different from most cytotoxic T cells and helper T cells, they play a supporting role in the immune system. What's more, regulatory T cells often play an immunosuppressive role, which mainly plays a role in maintaining the stability of the immune system and regulating the immune response in the body. However, recent studies have shown that not only playing a role in autoimmune diseases, organ transplantation, and other aspects, regulatory T cells can also play a role in the immune escape of tumors in the body, through various mechanisms to help tumor cells escape from the demic immune system, weakening the anti-cancer effect in the body. For a better understanding of the role that regulatory T cells can play in cancer, and to be able to use regulatory T cells for tumor immunotherapy more quickly. This review focuses on the research progress of various mechanisms of regulatory T cells in the tumor environment, the related research of tumor cells acting on regulatory T cells, and the existing various therapeutic methods acting on regulatory T cells.

Agonism of 4-1BB for immune therapy: a perspective on possibilities and complications

Costimulatory receptors on immune cells represent attractive targets for immunotherapy given that these molecules can increase the frequency of individual protective immune cell populations and their longevity, as well as enhance various effector functions. 4-1BB, a member of the TNF receptor superfamily, also known as CD137 and TNFRSF9, is one such molecule that is inducible on several cell types, including T cells and NK cells. Preclinical studies in animal models have validated the notion that stimulating 4-1BB with agonist reagents or its natural ligand could be useful to augment conventional T cell and NK cell immunity to protect against tumor growth and against viral infection. Additionally, stimulating 4-1BB can enhance regulatory T cell function and might be useful in the right context for suppressing autoimmunity. Two human agonist antibodies to 4-1BB have been produced and tested in clinical trials for cancer, with variable results, leading to the production of a wealth of second-generation antibody constructs, including bi- and multi-specifics, with the hope of optimizing activity and selectivity. Here, we review the progress to date in agonism of 4-1BB, discuss the complications in targeting the immune system appropriately to elicit the desired activity, together with challenges in engineering agonists, and highlight the untapped potential of manipulating this molecule in infectious disease and autoimmunity.

Type 1 diabetes and inborn errors of immunity: Complete strangers or 2 sides of the same coin?

Type 1 diabetes (T1D) is a polygenic disease and does not follow a mendelian pattern. Inborn errors of immunity (IEIs), on the other hand, are caused by damaging germline variants, suggesting that T1D and IEIs have nothing in common. Some IEIs, resulting from mutations in genes regulating regulatory T-cell homeostasis, are associated with elevated incidence of T1D. The genetic spectrum of IEIs is gradually being unraveled; consequently, molecular pathways underlying human monogenic autoimmunity are being identified. There is an appreciable overlap between some of these pathways and the genetic variants that determine T1D susceptibility, suggesting that after all, IEI and T1D are 2 sides of the same coin. The study of monogenic IEIs with a variable incidence of T1D has the potential to provide crucial insights into the mechanisms leading to T1D. These insights contribute to the definition of T1D endotypes and explain disease heterogeneity. In this review, we discuss the interconnected pathogenic pathways of autoimmunity, β-cell function, and primary immunodeficiency. We also examine the role of environmental factors in disease penetrance as well as the circumstantial evidence of IEI drugs in preventing and curing T1D in individuals with IEIs, suggesting the repositioning of these drugs also for T1D therapy.