Antigen-specific Helios- , Neuropilin-1- Tregs induce apoptosis of autoreactive B cells via PD-L1

Classification of regulatory T cells and their role in myocardial ischemia-reperfusion injury

Myocardial ischemia-reperfusion injury (MIRI) is closely related to the final infarct size in acute myocardial infarction (AMI). Therefore, reducing MIRI can effectively improve the prognosis of AMI patients. At the same time, the healing process after AMI is closely related to the local inflammatory microenvironment. Regulatory T cells (Tregs) can regulate various physiological and pathological immune inflammatory responses and play an important role in regulating the immune inflammatory response after AMI. However, different subtypes of Tregs have different effects on MIRI, and the same subtype of Tregs may also have different effects at different stages of MIRI. This article systematically reviews the classification and function of Tregs, as well as the role of various subtypes of Tregs in MIRI. A comprehensive understanding of the role of each subtype of Tregs can help design effective methods to control immune reactions, reduce MIRI, and provide new potential therapeutic options for AMI.

Regulatory T cells and cardiovascular diseases

ABSTRACT

Inflammation is a major underlying mechanism in the progression of numerous cardiovascular diseases (CVDs). Regulatory T cells (Tregs) are typical immune regulatory cells with recognized immunosuppressive properties. Despite the immunosuppressive properties, researchers have acknowledged the significance of Tregs in maintaining tissue homeostasis and facilitating repair/regeneration. Previous studies unveiled the heterogeneity of Tregs in the heart and aorta, which expanded in CVDs with unique transcriptional phenotypes and reparative/regenerative function. This review briefly summarizes the functional principles of Tregs, also including the synergistic effect of Tregs and other immune cells in CVDs. We discriminate the roles and therapeutic potential of Tregs in CVDs such as atherosclerosis, hypertension, abdominal arterial aneurysm, pulmonary arterial hypertension, Kawasaki disease, myocarditis, myocardial infarction, and heart failure. Tregs not only exert anti-inflammatory effects but also actively promote myocardial regeneration and vascular repair, maintaining the stability of the local microenvironment. Given that the specific mechanism of Tregs functioning in CVDs remains unclear, we reviewed previous clinical and basic studies and the latest findings on the function and mechanism of Tregs in CVDs.

Clinical adoptive regulatory T Cell therapy: State of the art, challenges, and prospective

Rejection of solid organ transplant and graft versus host disease (GvHD) continue to be challenging in post transplantation management. The introduction of calcineurin inhibitors dramatically improved recipients' short-term prognosis. However, long-term clinical outlook remains poor, moreover, the lifelong dependency on these toxic drugs leads to chronic deterioration of graft function, in particular the renal function, infections and de-novo malignancies. These observations led investigators to identify alternative therapeutic options to promote long-term graft survival, which could be used concomitantly, but preferably, replace pharmacologic immunosuppression as standard of care. Adoptive T cell (ATC) therapy has evolved as one of the most promising approaches in regenerative medicine in the recent years. A range of cell types with disparate immunoregulatory and regenerative properties are actively being investigated as potential therapeutic agents for specific transplant rejection, autoimmunity or injury-related indications. A significant body of data from preclinical models pointed to efficacy of cellular therapies. Significantly, early clinical trial observations have confirmed safety and tolerability, and yielded promising data in support of efficacy of the cellular therapeutics. The first class of these therapeutic agents commonly referred to as advanced therapy medicinal products have been approved and are now available for clinical use. Specifically, clinical trials have supported the utility of CD4⁺CD25+FOXP3+ regulatory T cells (Tregs) to minimize unwanted or overshooting immune responses and reduce the level of pharmacological immunosuppression in transplant recipients. Tregs are recognized as the principal orchestrators of maintaining peripheral tolerance, thereby blocking excessive immune responses and prevent autoimmunity. Here, we summarize rationale for the adoptive Treg therapy, challenges in manufacturing and clinical experiences with this novel living drug and outline future perspectives of its use in transplantation.

Immune tolerance against infused FVIII in hemophilia A is mediated by PD-L1+ Tregs

A major complication of hemophilia A therapy is the development of alloantibodies (inhibitors) that neutralize intravenously administered coagulation factor VIII (FVIII). Immune tolerance induction therapy (ITI) by repetitive FVIII injection can eradicate inhibitors, and thereby reduce morbidity and treatment costs. However, ITI success is difficult to predict and the underlying immunological mechanisms are unknown. Here, we demonstrated that immune tolerance against FVIII under nonhemophilic conditions was maintained by programmed death (PD) ligand 1-expressing (PD-L1-expressing) regulatory T cells (Tregs) that ligated PD-1 on FVIII-specific B cells, causing them to undergo apoptosis. FVIII-deficient mice injected with FVIII lacked such Tregs and developed inhibitors. Using an ITI mouse model, we found that repetitive FVIII injection induced FVIII-specific PD-L1+ Tregs and reengaged removal of inhibitor-forming B cells. We also demonstrated the existence of FVIII-specific Tregs in humans and showed that such Tregs upregulated PD-L1 in patients with hemophilia after successful ITI. Simultaneously, FVIII-specific B cells upregulated PD-1 and became killable by Tregs. In summary, we showed that PD-1-mediated B cell tolerance against FVIII operated in healthy individuals and in patients with hemophilia A without inhibitors, and that ITI reengaged this mechanism. These findings may impact monitoring of ITI success and treatment of patients with hemophilia A.

B cell-T cell interplay in immune regulation: A focus on follicular regulatory T and regulatory B cell functions

B cells are the core components of humoral immunity. A mature B cell can serve in multiple capacities, including antibody production, antigen presentation, and regulatory functions. Forkhead box P3 (FoxP3)-expressing regulatory T cells (Tregs) are key players in sustaining immune tolerance and keeping inflammation in check. Mounting evidence suggests complex communications between B cells and Tregs. In this review, we summarize the yin-yang regulatory relationships between B cells and Tregs mainly from the perspectives of T follicular regulatory (Tfr) cells and regulatory B cells (Bregs). We discuss the regulatory effects of Tfr cells on B cell proliferation and the germinal center response. Additionally, we review the indispensable role of B cells in ensuring homeostatic Treg survival and describe the function of Bregs in promoting Treg responses. Finally, we introduce a new subset of Tregs, termed Treg-of-B cells, which are induced by B cells, lake the expression of FoxP3 but still own immunomodulatory effects. In this article, we also enumerate a sequence of research from clinical patients and experimental models to clarify the role of Tfr cells in germinal centers and the role of convention B cells and Bregs to Tregs in the context of different diseases. This review offers an updated overview of immunoregulatory networks and unveils potential targets for therapeutic interventions against cancer, autoimmune diseases and allograft rejection.

METTL14 Acts as a Potential Regulator of Tumor Immune and Progression in Clear Cell Renal Cell Carcinoma

Clear cell renal cell carcinoma (ccRCC) is characterized by its insensitivity to chemoradiotherapy and lacks effective diagnostic and prognostic biomarkers. In this study, we focused on the role of m6A RNA methylation regulators for tumor immunity. Based on the expression of 20 m6A regulators, consensus clustering was performed to divide patients into cluster1/cluster2 and showed that there was a survival difference between the two clusters. Through cox regression analysis, five hub m6A regulators were screened to construct a risk model. Further analysis showed that the risk score was an independent prognostic factor. GSEA, GSVA, and KEGG analysis revealed that immune cell pathways played a critical role between the high risk group and low risk group. Combined with CIBERSORT and survival analysis, five hub tumor-infiltrating immune cells (TIICs) were identified for further study. Meanwhile, correlation analysis indicated that IGF2BP2 was positively associated with activated memory CD4 T cell and METTL14 was negatively correlated to the regulatory T cell. Therefore, IGF2BP2 and METTL14 were regarded as key genes. Further study verified that only METTL14 possessed good diagnostic and prognostic value. Then, GSEA exhibited that METTL14 was mainly enriched in chemokine related pathways. We also found that CCL5 was negatively correlated to METTL14 and might serve as a potential target of METTL14. In conclusion, these findings suggest that the METTL14/CCL5/Tregs axis is a potential signaling pathway for regulating tumor immunity, and might become novel therapeutic targets for ccRCC.

Dendritic Cells: Versatile Players in Renal Transplantation

Dendritic cells (DCs) induce and regulate adaptive immunity through migrating and maturing in the kidney. In this procedure, they can adopt different phenotypes—rejection-associated DCs promote acute or chronic injury renal grafts while tolerogenic DCs suppress the overwhelmed inflammation preventing damage to renal functionality. All the subsets interact with effector T cells and regulatory T cells (Tregs) stimulated by the ischemia–reperfusion procedure, although the classification corresponding to different effects remains controversial. Thus, in this review, we discuss the origin, maturation, and pathological effects of DCs in the kidney. Then we summarize the roles of divergent DCs in renal transplantation: taking both positive and negative stages in ischemia–reperfusion injury (IRI), switching phenotypes to induce acute or chronic rejection, and orchestrating surface markers for allograft tolerance via alterations in metabolism. In conclusion, we prospect that multidimensional transcriptomic analysis will revolute researches on renal transplantation by addressing the elusive mononuclear phagocyte classification and providing a holistic view of DC ontogeny and subpopulations.

Super-Treg: Toward a New Era of Adoptive Treg Therapy Enabled by Genetic Modifications

Regulatory Tcells (Treg) are essential components of peripheral immune homeostasis. Adoptive Treg cell therapy has shown efficacy in a variety of immune-mediated diseases in preclinical studies and is now moving from phase I/IIa to larger phase II studies aiming to demonstrate efficacy. However, hurdles such as in vivo stability and efficacy remain to be addressed. Nevertheless, preclinical models have shown that Treg function and specificity can be increased by pharmacological substances or gene modifications, and even that conventional T cells can be converted to Treg potentially providing new sources of Treg and facilitating Treg cell therapy. The exponential growth in genetic engineering techniques and their application to T cells coupled to a large body of knowledge on Treg open numerous opportunities to generate Treg with "superpowers". This review summarizes the genetic engineering techniques available and their applications for the next-generation of Super-Treg with increased function, stability, redirected specificity and survival.

Targeting neuropilin-1 interactions is a promising anti-tumor strategy

ABSTRACT

Neuropilins (NRP1 and NRP2) are multifunctional receptor proteins that are involved in nerve, blood vessel, and tumor development. NRP1 was first found to be expressed in neurons, but subsequent studies have demonstrated its surface expression in cells from the endothelium and lymph nodes. NRP1 has been demonstrated to be involved in the occurrence and development of a variety of cancers. NRP1 interacts with various cytokines, such as vascular endothelial growth factor family and its receptor and transforming growth factor β1 and its receptor, to affect tumor angiogenesis, tumor proliferation, and migration. In addition, NRP1+ regulatory T cells (Tregs) play an inhibitory role in tumor immunity. High numbers of NRP1+ Tregs were associated with cancer prognosis. Targeting NRP1 has shown promise, and antagonists against NRP1 have had therapeutic efficacy in preliminary clinical studies. NRP1 treatment modalities using nanomaterials, targeted drugs, oncolytic viruses, and radio-chemotherapy have gradually been developed. Hence, we reviewed the use of NRP1 in the context of tumorigenesis, progression, and treatment.

High-Dose IV Administration of Rasburicase Suppresses Anti-rasburicase Antibodies, Depletes Rasburicase-Specific Lymphocytes, and Upregulates Treg Cells

Therapeutic proteins can be potent agents for treating serious diseases, but in many patients these proteins provoke antibody responses that blunt therapeutic efficacy. Intravenous administration of high doses of some proteins induces immune tolerance, but the mechanisms underlying this effect are poorly understood. As a model to study tolerance induction in mice, we used rasburicase, a commercial recombinant uricase used for the treatment of hyperuricemia. Intraperitoneal (i.p.) injection of rasburicase without or with alum adjuvants induced a clear anti-rasburicase antibody response, but intravenous (i.v.) injection did not. The lack of response to i.v. rasburicase was apparently due to active immune suppression since i.v.-treated mice showed blunted antibody and reduced T cell responses to subsequent i.p. injections of rasburicase. This blunted response was associated with a decrease in rasburicase-specific B cell and T cell responses and an increase in proportion of CD4⁺ FoxP3⁺ regulatory T cells (Treg) in the spleen. We examined the number of lymphocytes in peripheral blood after rasburicase i.v. injection. Rasburicase caused a transient reduction in B and T cells, but a robust and sustained depletion of rasburicase-specific B cells. Further experiments showed that rasburicase i.v. injection decreased the number of lymphocytes and was associated with apoptosis of both B cells and activated T cells and that the enhanced percentage of Treg cells was likely mediated by a macrophage-dependent pathway. Thus, our data suggest that apoptosis and depletion of antigen-specific B lymphocytes and upregulation of Treg cells may play important roles in the immune suppression induced by intravenous administration of a therapeutic protein.

Kidney dendritic cells: fundamental biology and functional roles in health and disease

Dendritic cells (DCs) are chief inducers of adaptive immunity and regulate local inflammatory responses across the body. Together with macrophages, the other main type of mononuclear phagocyte, DCs constitute the most abundant component of the intrarenal immune system. This network of functionally specialized immune cells constantly surveys its microenvironment for signs of injury or infection, which trigger the initiation of an immune response. In the healthy kidney, DCs coordinate effective immune responses, for example, by recruiting neutrophils for bacterial clearance in pyelonephritis. The pro-inflammatory actions of DCs can, however, also contribute to tissue damage in various types of acute kidney injury and chronic glomerulonephritis, as DCs recruit and activate effector T cells, which release toxic mediators and maintain tubulointerstitial immune infiltrates. These actions are counterbalanced by DC subsets that promote the activation and maintenance of regulatory T cells to support resolution of the immune response and allow kidney repair. Several studies have investigated the multiple roles for DCs in kidney homeostasis and disease, but it has become clear that current tools and subset markers are not sufficient to accurately distinguish DCs from macrophages. Multidimensional transcriptomic analysis studies promise to improve mononuclear phagocyte classification and provide a clearer view of DC ontogeny and subsets.

CD4+CD25highCD127low/-FoxP3 + Regulatory T-Cell Population in Acute Leukemias: A Review of the Literature

Regulatory T-cells (Tregs) are a very important subtype of lymphocytes when it comes to self-control in the human immunological system. Tregs are decisive not only in the protection against destruction of own tissues by autoimmune immunocompetent cells but also in the immunological answer to developing cancers. On the other hand, Tregs could be responsible for the progression of acute and chronic leukemias. In our study, we review publications available in the PUMED database concerning acute leukemia, with a particular emphasis on child's leukemias. The percentage of regulatory T-lymphocytes in peripheral blood and bone marrow was elevated compared to those in healthy individuals and correlated with progressive disease. Regulatory T-cells taken from children diagnosed with leukemia showed a higher suppressive capability, which was confirmed by detecting elevated levels of secreted IL-10 and TGF-beta. The possibility of pharmacological intervention in the self-control of the immunological system is now under extensive investigation in many human cancers. Presumably, Treg cells could be a vital part of targeted therapies. Routine Treg determination could be used to assess the severity of disease and prognosis in children with acute lymphoblastic leukemia. This proposition results from the fact that in some studies, higher percentage of Treg cells in peripheral blood was demonstrated. However, observations confirming these facts are scarce; thus, extrapolating them to the population of children with hematological malignancies needs to be verified in additional studies.