Immunotherapy of autoimmune encephalomyelitis with redirected CD4+CD25+ T lymphocytes

CD4+CD25+ regulatory T cells ex vivo generated from autologous naïve CD4+ T cells suppress EAE progression

CD4+CD25+ regulatory T cells (Tregs) play an important role in maintaining immune homeostasis in multiple sclerosis (MS). Hence, we aimed to explore the therapeutic efficacy and safety of adoptive cell therapy (ACT) utilizing induced antigen-specific Tregs in an animal model of MS, that is, in an experimental autoimmune encephalomyelitis (EAE) model. B cells from EAE model that were activated with soluble CD40L were used as antigen-presenting cells (APCs) to induce the differentiation of antigen-specific Tregs from naïve CD4 precursors, and then, a stepwise isolation of CD4+CD25highCD127low Tregs was performed using a flow sorter. All EAE mice were divided into Treg-treated group (2 × 104 cells in 0.2 mL per mouse, n = 14) and sham-treated group (0.2 mL normal saline (NS), n = 20), which were observed daily for clinical assessment, and for abnormal appearance for 6 weeks. Afterward, histological analysis, immunofluorescence and real-time PCR were performed. Compared to sham-treated mice, Treg-treated mice exhibited a significant decrease in disease severity scores and reduced inflammatory infiltration and demyelination in the spinal cord. Additionally, Tregs-treated mice demonstrated higher CCN3 protein and mRNA levels than sham-treated mice. The results of this preclinical study further support the therapeutic potential of this ACT approach in the treatment of MS.

Eras of designer Tregs: Harnessing synthetic biology for immune suppression

Since their discovery, CD4+ CD25hi FOXP3hi regulatory T cells (Tregs) have been firmly established as a critical cell type for regulating immune homeostasis through a plethora of mechanisms. Due to their immunoregulatory power, delivery of polyclonal Tregs has been explored as a therapy to dampen inflammation in the settings of transplantation and autoimmunity. Evidence shows that Treg therapy is safe and well-tolerated, but efficacy remains undefined and could be limited by poor persistence in vivo and lack of antigen specificity. With the advent of new genetic engineering tools, it is now possible to create bespoke "designer" Tregs that not only overcome possible limitations of polyclonal Tregs but also introduce new features. Here, we review the development of designer Tregs through the perspective of three 'eras': (1) the era of FOXP3 engineering, in which breakthroughs in the biological understanding of this transcription factor enabled the conversion of conventional T cells to Tregs; (2) the antigen-specificity era, in which transgenic T-cell receptors and chimeric antigen receptors were introduced to create more potent and directed Treg therapies; and (3) the current era, which is harnessing advanced genome-editing techniques to introduce and refine existing and new engineering approaches. The year 2022 marked the entry of "designer" Tregs into the clinic, with exciting potential for application and efficacy in a wide variety of immune-mediated diseases.

Engineered Treg cells as putative therapeutics against inflammatory diseases and beyond

Regulatory T (Treg) cells ensure tolerance against self-antigens, limit excessive inflammation, and support tissue repair processes. Therefore, Treg cells are currently attractive candidates for the treatment of certain inflammatory diseases, autoimmune disorders, or transplant rejection. Early clinical trials have proved the safety and efficacy of certain Treg cell therapies in inflammatory diseases. We summarize recent advances in engineering Treg cells, including the concept of biosensors for inflammation. We assess Treg cell engineering possibilities for novel functional units, including Treg cell modifications influencing stability, migration, and tissue adaptation. Finally, we outline perspectives of engineered Treg cells going beyond inflammatory diseases by using custom-designed receptors and read-out systems, aiming to use Treg cells as in vivo diagnostic tools and drug delivery vehicles.

The emerging role of regulatory cell-based therapy in autoimmune disease

Autoimmune disease, caused by unwanted immune responses to self-antigens, affects millions of people each year and poses a great social and economic burden to individuals and communities. In the course of autoimmune disorders, including rheumatoid arthritis, systemic lupus erythematosus, type 1 diabetes mellitus, and multiple sclerosis, disturbances in the balance between the immune response against harmful agents and tolerance towards self-antigens lead to an immune response against self-tissues. In recent years, various regulatory immune cells have been identified. Disruptions in the quality, quantity, and function of these cells have been implicated in autoimmune disease development. Therefore, targeting or engineering these cells is a promising therapeutic for different autoimmune diseases. Regulatory T cells, regulatory B cells, regulatory dendritic cells, myeloid suppressor cells, and some subsets of innate lymphoid cells are arising as important players among this class of cells. Here, we review the roles of each suppressive cell type in the immune system during homeostasis and in the development of autoimmunity. Moreover, we discuss the current and future therapeutic potential of each one of these cell types for autoimmune diseases.

[Increased suppressor activity of transformed ex vivo regulatory T-cells in comparison with unstimulated cells of the same donor]

Regulatory T-cells CD4⁺CD25⁺FoxP3⁺CD127low (Tregs) play a key role in the maintenance of tolerance to auto antigens, inhibit function of effector T and B lymphocytes, and provide a balance between effector and regulatory arms of immunity. Patients with autoimmune diseases have decreased Treg numbers and impaired suppressive activity. Transformed ex vivo autologous Tregs could restore destroyed balance of the immune system. We developed a method for Treg precursor cell cultivation. Following the method, we were able to grown up 300-400 million of Tregs cells from 50 ml of peripheral blood during a week. Transformed ex vivo Tregs are 90-95% CD4⁺CD25⁺FoxP3⁺CD127low and have increased expression of transcription genes FoxP3 and Helios. Transformed ex vivo Tregs have increased demethylation of FoxP3 promoter and activated genes of proliferation markers Cycline B1, Ki67 and LGALS 1. Transformed ex vivo Tregs have increased suppressive activity and up to 80-90% these cells secrete cytokines TNFα и IFNγ. Our data suggest transformed ex vivo autologous Tregs have genetic, immunophenotypic and functional characteristics for regulatory T-cells and further can be used for adoptive immunotherapy autoimmune diseases and inhibition of transplantation immunity.

Modulating immune responses to AAV by expanded polyclonal T-regs and capsid specific chimeric antigen receptor T-regulatory cells

Immune responses to adeno-associated virus (AAV) capsids limit the therapeutic potential of AAV gene therapy. Herein, we model clinical immune responses by generating AAV capsid-specific chimeric antigen receptor (AAV-CAR) T cells. We then modulate immune responses to AAV capsid with AAV-CAR regulatory T cells (Tregs). AAV-CAR Tregs in vitro display phenotypical Treg surface marker expression, and functional suppression of effector T cell proliferation and cytotoxicity. In mouse models, AAV-CAR Tregs mediated continued transgene expression from an immunogenic capsid, despite antibody responses, produced immunosuppressive cytokines, and decreased tissue inflammation. AAV-CAR Tregs are also able to bystander suppress immune responses to immunogenic transgenes similarly mediating continued transgene expression, producing immunosuppressive cytokines, and reducing tissue infiltration. Taken together, AAV-CAR T cells and AAV-CAR Tregs are directed and powerful immunosuppressive tools to model and modulate immune responses to AAV capsids and transgenes in the local environment.

The mosaic of autoimmunity - A taste for more. The 12th international congress of autoimmunity 2021 (AUTO12) virtual

Notwithstanding the fact that the 12th international congress of autoimmunity (AUTO12) was held virtual this year, the number of the abstracts submitted and those presented crossed the thousand marks. Leading investigators and researchers from all over the world presented the latest developments of their research in the domain of autoimmunity and its correlation with various diseases. In terms of mechanisms of autoimmunity, an update on the mechanisms behind the association of autoimmunity with systemic diseases focusing on hyperstimulation was presented during AUTO12. In addition, a new mechanism of ASIA syndrome caused by an intrauterine contraceptive device was revealed demonstrating a complete resolution of symptoms following device removal. In regard to the correlation between autoimmunity and neurogenerative diseases, the loss of structural protein integrity as the trigger of immunological response was shown. Schizophrenia as well, and its correlation to pro-inflammatory cytokines was also addressed. Furthermore, and as it was said AUTO12 virtual due to COVID-19 pandemic, various works were dedicated to SARS-CoV-2 infection and COVID-19 in terms of autoimmune mechanisms involved in the pathogenesis, treatment and complications of COVID-19. For instance, the correlation between autoimmunity and the severity of COVID-19 was viewed. Moreover, the presence and association of autoantibodies in COVID-19 was also demonstrated, as well as the clinical outcomes of COVID-19 in patients with rheumatic diseases. Finally, immune-mediated reactions and processes secondary to SARS-CoV-2 vaccination was displayed. Due to the immense importance of all of the topics addressed and while several hundreds of works were presented which cannot be summed up in one paper, we aimed hereby to highlight some of the outstanding abstracts and presentations during AUTO12.

Made to Measure: Patient-Tailored Treatment of Multiple Sclerosis Using Cell-Based Therapies

Currently, there is still no cure for multiple sclerosis (MS), which is an autoimmune and neurodegenerative disease of the central nervous system. Treatment options predominantly consist of drugs that affect adaptive immunity and lead to a reduction of the inflammatory disease activity. A broad range of possible cell-based therapeutic options are being explored in the treatment of autoimmune diseases, including MS. This review aims to provide an overview of recent and future advances in the development of cell-based treatment options for the induction of tolerance in MS. Here, we will focus on haematopoietic stem cells, mesenchymal stromal cells, regulatory T cells and dendritic cells. We will also focus on less familiar cell types that are used in cell therapy, including B cells, natural killer cells and peripheral blood mononuclear cells. We will address key issues regarding the depicted therapies and highlight the major challenges that lie ahead to successfully reverse autoimmune diseases, such as MS, while minimising the side effects. Although cell-based therapies are well known and used in the treatment of several cancers, cell-based treatment options hold promise for the future treatment of autoimmune diseases in general, and MS in particular.

Improving the Efficacy of Regulatory T Cell Therapy

Autoimmunity is caused by an unbalanced immune system, giving rise to a variety of organ-specific to system disorders. Patients with autoimmune diseases are commonly treated with broad-acting immunomodulatory drugs, with the risk of severe side effects. Regulatory T cells (Tregs) have the inherent capacity to induce peripheral tolerance as well as tissue regeneration and are therefore a prime candidate to use as cell therapy in patients with autoimmune disorders. (Pre)clinical studies using Treg therapy have already established safety and feasibility, and some show clinical benefits. However, Tregs are known to be functionally impaired in autoimmune diseases. Therefore, ex vivo manipulation to boost and stably maintain their suppressive function is necessary when considering autologous transplantation. Similar to autoimmunity, severe coronavirus disease 2019 (COVID-19) is characterized by an exaggerated immune reaction and altered Treg responses. In light of this, Treg-based therapies are currently under investigation to treat severe COVID-19. This review provides a detailed overview of the current progress and clinical challenges of Treg therapy for autoimmune and hyperinflammatory diseases, with a focus on recent successes of ex vivo Treg manipulation.

Autoimmune Disorders of the Nervous System: Pathophysiology, Clinical Features, and Therapy

Remarkable discoveries over the last two decades have elucidated the autoimmune basis of several, previously poorly understood, neurological disorders. Autoimmune disorders of the nervous system may affect any part of the nervous system, including the brain and spinal cord (central nervous system, CNS) and also the peripheral nerves, neuromuscular junction and skeletal muscle (peripheral nervous system, PNS). This comprehensive overview of this rapidly evolving field presents the factors which may trigger breakdown of self-tolerance and development of autoimmune disease in some individuals. Then the pathophysiological basis and clinical features of autoimmune diseases of the nervous system are outlined, with an emphasis on the features which are important to recognize for accurate clinical diagnosis. Finally the latest therapies for autoimmune CNS and PNS disorders and their mechanisms of action and the most promising research avenues for targeted immunotherapy are discussed.

How to Combine the Two Landmark Treatment Methods-Allogeneic Hematopoietic Stem Cell Transplantation and Chimeric Antigen Receptor T Cell Therapy Together to Cure High-Risk B Cell Acute Lymphoblastic Leukemia?

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) has made tremendous progress in the last few decades and is increasingly being used worldwide. The success of haploidentical HSCT has made it possible to have "a donor for everyone". Patients who received transplantation in remission may have a favorable outcome, while those who were transplanted in advanced stages of disease have a poor prognosis. Although chimeric antigen receptor T (CAR-T) cell therapy is currently a milestone in the immunotherapy of relapsed or refractory (R/R) B cell acute lymphoblastic leukemia (B-ALL) and has demonstrated high remission rates in patients previously treated in multiple lines, the relatively high relapse rate remains a barrier to CAR-T cell therapy becoming an excellent cure option. Therefore, combining these two approaches (allo-HSCT and CAR-T cell therapy) is an attractive area of research to further improve the prognosis of R/R B-ALL. In this review, we will discuss the current clinical practices of combining allo-HSCT with CAR-T cell therapy based on available data, including CAR-T cells as a bridge to allo-HSCT for R/R B-ALL and CAR-T cell infusion for post-transplant relapse. We will further explore not only other possible ways to combine the two approaches, including CAR-T cell therapy to clear minimal residual disease peri-transplantation and incorporation of CAR technology to treat graft-versus-host disease, but also the potential of CAR-T cells as a part of allo-HSCT.

Regulating the regulators: Is introduction of an antigen-specific approach in regulatory T cells the next step to treat autoimmunity?

In autoimmunity, the important and fragile balance between immunity and tolerance is disturbed, resulting in abnormal immune responses to the body's own tissues and cells. CD4⁺CD25^hiFoxP3⁺ regulatory T cells (Tregs) induce peripheral tolerance in vivo by means of direct cell-cell contact and release of soluble factors, or indirectly through antigen-presenting cells (APC), thereby controlling auto-reactive effector T cells. Based on these unique capacities of Tregs, preclinical studies delivered proof-of-principle for the clinical use of Tregs for the treatment of autoimmune diseases. To date, the first clinical trials using ex vivo expanded polyclonal Tregs have been completed. These pioneering studies demonstrate the feasibility of generating large numbers of polyclonal Tregs in a good manufacturing practices (GMP)-compliant manner, and that infusion of Tregs is well tolerated by patients with no evidence of general immunosuppression. Nonetheless, only modest clinical results were observed, arguing that a more antigen-specific approach might be needed to foster a durable patient-specific clinical cell therapy without the risk for general immunosuppression. In this review, we discuss current knowledge, applications and future goals of adoptive immune-modulatory Treg therapy for the treatment of autoimmune disease and transplant rejection. We describe the key advances and prospects of the potential use of T cell receptor (TCR)- and chimeric antigen receptor (CAR)-engineered Tregs in future clinical applications. These approaches could deliver the long-awaited breakthrough in stopping undesired autoimmune responses and transplant rejections.

Engineered regulatory T cells expressing myelin-specific chimeric antigen receptors suppress EAE progression

The expansion of polyclonal T regulatory cells (Tregs) offers great promise for the treatment of immune-mediated diseases, such as multiple sclerosis (MS). However, polyclonal Tregs can be non-specifically immunosuppressive. Based on the advancements with chimeric antigen receptor (CAR) therapy in leukemia, we previously engineered Tregs to express a T-cell receptor (TCR) specific for a myelin basic protein (MBP) peptide. These TCR-engineered specific Tregs suppressed the proliferation of MBP-reactive T effector cells and ameliorated myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE). Herein, we extend this approach by creating human regulatory T cells expressing functional single-chain chimeric antigen receptors (scFv CAR), targeting either MBP or MOG. These scFv CAR-transduced Tregs retained FoxP3 and Helios, characteristic of Treg cells, after long-term expansion in vitro. Importantly, these engineered CNS targeting CAR-Tregs were able to suppress autoimmune pathology in EAE, demonstrating that these Tregs have the potential to be used as a cellular therapy for MS patients.

Treg Enhancing Therapies to Treat Autoimmune Diseases

Regulatory T cells (Tregs) are a small yet critical subset of CD4+ T cells, which have the role of maintaining immune homeostasis by, for example, regulating self-tolerance, tumor immunity, anti-microbial resistance, allergy and transplantation rejection. The suppressive mechanisms by which Tregs function are varied and pleiotropic. The ability of Tregs to maintain self-tolerance means they are critical for the control and prevention of autoimmune diseases. Irregularities in Treg function and number can result in loss of tolerance and autoimmune disease. Restoring immune homeostasis and tolerance through the promotion, activation or delivery of Tregs has emerged as a focus for therapies aimed at curing or controlling autoimmune diseases. Such therapies have focused on the Treg cell subset by using drugs to suppress T effector cells and promote Tregs. Other approaches have trialed inducing tolerance by administering the autoantigen via direct administration, by transient expression using a DNA vector, or by antigen-specific nanoparticles. More recently, cell-based therapies have been developed as an approach to directly or indirectly enhance Treg cell specificity, function and number. This can be achieved indirectly by transfer of tolerogenic dendritic cells, which have the potential to expand antigen-specific Treg cells. Treg cells can be directly administered to treat autoimmune disease by way of polyclonal Tregs or Tregs transduced with a receptor with high affinity for the target autoantigen, such as a high affinity T cell receptor (TCR) or a chimeric antigen receptor (CAR). This review will discuss the strategies being developed to redirect autoimmune responses to a state of immune tolerance, with the aim of the prevention or amelioration of autoimmune disease.

From Cancer to Immune-Mediated Diseases and Tolerance Induction: Lessons Learned From Immune Oncology and Classical Anti-cancer Treatment

Success in cancer treatment over the last four decades has ranged from improvements in classical drug therapy to immune oncology. Anti-cancer drugs have also often proven beneficial for the treatment of inflammatory and autoimmune diseases. In this review, we report on challenging examples that bridge between treatment of cancer and immune-mediated diseases, addressing mechanisms and experimental models as well as clinical investigations. Patient-derived tumor xenograft (PDX) (humanized) mouse models represent useful tools for preclinical evaluation of new therapies and biomarker identification. However, new developments using human ex vivo approaches modeling cancer, for example in microfluidic human organs-on-chips, promise to identify key molecular, cellular and immunological features of human cancer progression in a fully human setting. Classical drugs which bridge the gap, for instance, include cytotoxic drugs, proteasome inhibitors, PI3K/mTOR inhibitors and metabolic inhibitors. Biologicals developed for cancer therapy have also shown efficacy in the treatment of autoimmune diseases. In immune oncology, redirected chimeric antigen receptor (CAR) T cells have achieved spectacular remissions in refractory B cell leukemia and lymphoma and are currently under development for tolerance induction using cell-based therapies such as CAR Tregs or NK cells. Finally, a brief outline will be given of the lessons learned from bridging cancer and autoimmune diseases as well as tolerance induction.

Autoantigen specific IL-2 activated CD4+CD25+T regulatory cells inhibit induction of experimental autoimmune neuritis

Experimental autoimmune neuritis (EAN) induced by peripheral nerve myelin (PNM) is self-limiting and re-immunization with PNM does not re-activate disease. This study showed inhibition of EAN by CD4⁺CD25⁺T cells both from sensitized hosts or from naïve hosts after ex-vivo activation by PNM and rIL-2. Transfer of naïve CD4⁺CD25⁺T cells has no effect on EAN, nor did naïve CD4⁺CD25⁺T cells activated with rIL-2 and renal tubular antigen. Culture of naive CD4⁺CD25⁺Treg with rIL-2 and PNM induced mRNA for the IFN-gamma receptor. We showed naïve CD4⁺CD25⁺T cells activated by specific auto-antigen and rIL-2 produced more potent antigen-specific Treg that may have therapeutic potential.

Next-generation regulatory T cell therapy

Regulatory T cells (Treg cells) are a small subset of immune cells that are dedicated to curbing excessive immune activation and maintaining immune homeostasis. Accordingly, deficiencies in Treg cell development or function result in uncontrolled immune responses and tissue destruction and can lead to inflammatory disorders such as graft-versus-host disease, transplant rejection and autoimmune diseases. As Treg cells deploy more than a dozen molecular mechanisms to suppress immune responses, they have potential as multifaceted adaptable smart therapeutics for treating inflammatory disorders. Indeed, early-phase clinical trials of Treg cell therapy have shown feasibility, tolerability and potential efficacy in these disease settings. In the meantime, progress in the development of chimeric antigen receptors and in genome editing (including the application of CRISPR-Cas9) over the past two decades has facilitated the genetic optimization of primary T cell therapy for cancer. These technologies are now being used to enhance the specificity and functionality of Treg cells. In this Review, we describe the key advances and prospects in designing and implementing Treg cell-based therapy in autoimmunity and transplantation.

Antigen-specific therapeutic approaches for autoimmunity

The main function of the immune system in health is to protect the host from infection by microbes and parasites. Because immune responses to nonself bear the risk of unleashing accidental immunity against self, evolution has endowed the immune system with central and peripheral mechanisms of tolerance, including regulatory T and B cells. Although the past two decades have witnessed the successful clinical translation of a whole host of novel therapies for the treatment of chronic inflammation, the development of antigen-based approaches capable of selectively blunting autoimmune inflammation without impairing normal immunity has remained elusive. Earlier autoantigen-specific approaches employing peptides or whole antigens have evolved into strategies that seek to preferentially deliver these molecules to autoreactive T cells either indirectly, via antigen-presenting cells, or directly, via major histocompatibility complex molecules, in ways intended to promote clonal deletion and/or immunoregulation. The disease specificity, mechanistic underpinnings, developability and translational potential of many of these strategies remain unclear.

Th lymphocyte subsets in patients with Vogt-Koyanagi-Harada disease

AIM

To assess helper T (Th) lymphocyte subset balance in patients with Vogt-Koyanagi-Harada (VKH) disease.

METHODS

Sixty-eight active VKH patients and seventy-two inactive VKH patients were included in this study. One hundred healthy individuals served as controls. Peripheral blood was obtained from VKH patients and healthy controls. Th lymphocyte subsets were analyzed by flow cytometry. Plasma concentration of interleukin (IL)-17, IL-10, transforming growth factor (TGF)-β, IL-23 and IL-6 was examined by enzyme-linked immunosorbent assay (ELISA).

RESULTS

VKH patients with active uveitis had significantly higher percentages of both Th1 and Th17 cells and lower percentages of regulatory T (Treg) cells as compared with inactive VKH patients and healthy controls. Th1/Th2 and Th17/Treg ratios were also significantly elevated in active VKH patients. The percentages of Th1, Th17 and Treg cells and the Th1/Th2, Th17/Treg ratio did not differ between inactive VKH patients and healthy controls. There was no difference concerning the percentage of Th2 cells among all the groups. VKH patients with active uveitis showed an elevated level of peripheral Th17 related cytokines levels (TGF-β, IL-6, IL-23, and IL-17) and a decreased level of Treg related cytokines (IL-10) compared with inactive VKH patients and healthy controls. Inactive VKH patients showed no differences in peripheral Th17 related cytokines (TGF-β, IL-6, IL-23, and IL-17) and Treg related cytokines (IL-10) levels compared with healthy controls.

CONCLUSION

Th1 and Th17 cells are significantly increased and Treg cells significantly decreased in active VKH compared with inactive VKH or healthy controls. Therefore, Th lymphocyte subset analysis may serve as a disease biomarker for VKH.

The change of Th17/Treg cells and IL-10/IL-17 in Chinese children with Henoch-Schonlein purpura: A PRISMA-compliant meta-analysis

BACKGROUND

To date, the relationship of Th17 and Treg cells to Henoch-Schonlein purpura (HSP) in children remains controversial. Therefore, a systematic review and meta-analysis was conducted to reveal the potential role of the Th17 and Treg cells in children in acute stage of HSP.

METHODS

PubMed, Embase, Web of Science and China National Knowledge Internet (CNKI) were systematically searched for eligible studies up to November 03, 2017. Quality assessment was carried out according to the modification of the Newcastle-Ottawa Scale (NOS). The data were analyzed by Stata SE12.0 (StataCorp, College Station, TX). Standard mean difference (SMD) with 95% confidence intervals (CI) was calculated continuous data.

RESULTS

A total of 25 eligible studies were identified after a thorough literature search. The pooled results of the meta-analysis showed that values of Th17 frequency (SMD = 2.60; 95% CI: 1.98 to 3.23; P < .0001; I = 90.3%, P < .0001) and IL-17 level (SMD = 3.53; 95% CI: 2.71 to 4.35; P < .0001; I = 95.6%, P < .001) were significantly higher in children with HSP as compared to healthy children. In contrast, our analysis showed significant lower values of Treg frequency (SMD = -2.86; 95% CI: -3.53 to -2.19; P < .001; I = 92.4%, P < .001). However, no significance of IL-10 level was observed between children with HSP and healthy children (SMD = -1.22; 95% CI: -2.78 to 0.33; P < .01; I = 95.9%, P < .001).

CONCLUSION

In conclusion, our meta-analysis indicated that increased frequency of Th17 cells and level of IL-17, but lower frequency of Treg cells are associated with HSP in childhood. Considering the limitations of this meta-analysis, large-scaled studies need to be conducted to validate the current results.

Gene editing for inflammatory disorders

Technology for precise and efficient genetic editing is constantly evolving and is now capable of human clinical applications. Autoimmune and inflammatory diseases are chronic, disabling, sometimes life-threatening, conditions that feature heritable components. Both primary genetic lesions and the inflammatory pathobiology underlying these diseases represent fertile soil for new therapies based on the capabilities of gene editing. The ability to orchestrate precise targeted modifications to the genome will likely enable cell-based therapies for inflammatory diseases such as monogenic autoinflammatory disease, acquired autoimmune disease and for regenerative medicine in the setting of an inflammatory environment. Here, we discuss recent advances in genome editing and their evolving applications in immunoinflammatory diseases. Strengths and limitations of older genetic modification tools are compared with CRISPR/Cas9, base editing, RNA editing, targeted activators and repressors of transcription and targeted epigenetic modifiers. Commonly employed delivery vehicles to target cells or tissues of interest with genetic modification machinery, including viral, non-viral and cellular vectors, are described. Finally, applications in animal and human models of inflammatory diseases are discussed. Use of chimeric autoantigen receptor T cells, correction of monogenic diseases with genetically edited haematopoietic stem and progenitor cells, engineering of induced pluripotent stem cells and ex vivo expansion and modification of regulatory T cells for a range of chronic inflammatory diseases are reviewed.

TGF-β-responsive CAR-T cells promote anti-tumor immune function

A chimeric antigen receptor (CAR) that responds to transforming growth factor beta (TGF‐β) enables the engineering of T cells that convert this immunosuppressive cytokine into a potent T‐cell stimulant. However, clinical translation of TGF‐β CAR‐T cells for cancer therapy requires the ability to productively combine TGF‐β responsiveness with tumor‐targeting specificity. Furthermore, the potential concern that contaminating, TGF‐β?producing regulatory T (Treg) cells may preferentially expand during TGF‐β CAR‐T cell manufacturing and suppress effector T (Teff) cells demands careful evaluation. Here, we demonstrate that TGF‐β CAR‐T cells significantly improve the anti‐tumor efficacy of neighboring cytotoxic T cells. Furthermore, the introduction of TGF‐β CARs into mixed T‐cell populations does not result in the preferential expansion of Treg cells, nor do TGF‐β CAR‐Treg cells cause CAR‐mediated suppression of Teff cells. These results support the utility of incorporating TGF‐β CARs in the development of adoptive T‐cell therapy for cancer.

Gene Therapy With Regulatory T Cells: A Beneficial Alliance

Gene therapy aims to replace a defective or a deficient protein at therapeutic or curative levels. Improved vector designs have enhanced safety, efficacy, and delivery, with potential for lasting treatment. However, innate and adaptive immune responses to the viral vector and transgene product remain obstacles to the establishment of therapeutic efficacy. It is widely accepted that endogenous regulatory T cells (Tregs) are critical for tolerance induction to the transgene product and in some cases the viral vector. There are two basic strategies to harness the suppressive ability of Tregs: in vivo induction of adaptive Tregs specific to the introduced gene product and concurrent administration of autologous, ex vivo expanded Tregs. The latter may be polyclonal or engineered to direct specificity to the therapeutic antigen. Recent clinical trials have advanced adoptive immunotherapy with Tregs for the treatment of autoimmune disease and in patients receiving cell transplants. Here, we highlight the potential benefit of combining gene therapy with Treg adoptive transfer to achieve a sustained transgene expression. Furthermore, techniques to engineer antigen-specific Treg cell populations, either through reprogramming conventional CD4⁺ T cells or transferring T cell receptors with known specificity into polyclonal Tregs, are promising in preclinical studies. Thus, based upon these observations and the successful use of chimeric (IgG-based) antigen receptors (CARs) in antigen-specific effector T cells, different types of CAR-Tregs could be added to the repertoire of inhibitory modalities to suppress immune responses to therapeutic cargos of gene therapy vectors. The diverse approaches to harness the ability of Tregs to suppress unwanted immune responses to gene therapy and their perspectives are reviewed in this article.

The role of Th17/Treg-mediated immunoregulation in abortion mice

In the study, we investigated the immune factors related to T helper 17 (Th17) cells and T regulatory (Treg) cells in spontaneous abortion mice. The expression of Th17 was analyzed by interleukin (IL)-6, IL-17A secretion, RAR-related orphan receptor γt (RORγt) expression, and proportion of CD4+IL-17+ cells. The levels of IL-10, transforming growth factor β (TGF-β), Foxp3, and CD4+Foxp3+ cells were presented the Treg expression. Higher embryo absorption rate was found in spontaneous abortion group than that in normal pregnancy group ( P < 0.01). Compared with the normal pregnancy mice, spontaneous abortion mice showed higher levels of IL-6 and IL-17A and lower levels of IL-10 and TGF-β in serum and in decidua ( P < 0.05). Furthermore, the expressions of Foxp3 and CD4+Foxp3+ cells were significantly decreased in spontaneous abortion mice than those in normal pregnancy mice ( P < 0.05). However, the levels of RORγt and CD4+IL-17+ cells remarkably increased in spontaneous abortion mice ( P < 0.05). The results reveal that Th17/Treg cells may play a vital role in immunoregulation during pregnancy.

CD137+CD154- Expression As a Regulatory T Cell (Treg)-Specific Activation Signature for Identification and Sorting of Stable Human Tregs from In Vitro Expansion Cultures

Regulatory T cells (Tregs) are an attractive therapeutic tool for several different immune pathologies. Therapeutic Treg application often requires prolonged in vitro culture to generate sufficient Treg numbers or to optimize their functionality, e.g., via genetic engineering of their antigen receptors. However, purity of clinical Treg expansion cultures is highly variable, and currently, it is impossible to identify and separate stable Tregs from contaminating effector T cells, either ex vivo or after prior expansion. This represents a major obstacle for quality assurance of expanded Tregs and raises significant safety concerns. Here, we describe a Treg activation signature that allows identification and sorting of epigenetically imprinted Tregs even after prolonged in vitro culture. We show that short-term reactivation resulted in expression of CD137 but not CD154 on stable FoxP3+ Tregs that displayed a demethylated Treg-specific demethylated region, high suppressive potential, and lack of inflammatory cytokine expression. We also applied this Treg activation signature for rapid testing of chimeric antigen receptor functionality in human Tregs and identified major differences in the signaling requirements regarding CD137 versus CD28 costimulation. Taken together, CD137+CD154- expression emerges as a universal Treg activation signature ex vivo and upon in vitro expansion allowing the identification and isolation of epigenetically stable antigen-activated Tregs and providing a means for their rapid functional testing in vitro.

Clinical Applications of Regulatory T cells in Adoptive Cell Therapies

Interest in adoptive T-cell therapies has been ignited by the recent clinical success of genetically-modified T cells in the cancer immunotherapy space. In addition to immune targeting for malignancies, this approach is now being explored for the establishment of immune tolerance with regulatory T cells (Tregs). Herein, we will summarize the basic science and clinical results emanating from trials directed at inducing durable immune regulation through administration of Tregs. We will discuss some of the current challenges facing the field in terms of maximizing cell purity, stability and expansion capacity, while also achieving feasibility and GMP production. Indeed, recent advances in methodologies for Treg isolation, expansion, and optimal source materials represent important strides toward these considerations. Finally, we will review the emerging genetic and biomaterial-based approaches on the horizon for directing Treg specificity to augment tissue-targeting and regenerative medicine.

CARs: Synthetic Immunoreceptors for Cancer Therapy and Beyond

Chimeric antigen receptors (CARs) are versatile synthetic receptors that provide T cells with engineered specificity. Clinical success in treating B-cell malignancies has demonstrated the therapeutic potential of CAR-T cells against cancer, and efforts are underway to expand the use of engineered T cells to the treatment of diverse medical conditions, including infections and autoimmune diseases. Here, we review current understanding of the molecular properties of CARs, how this knowledge informs the rational design and characterization of novel receptors, the successes and shortcomings of CAR-T cells in the clinic, and emerging solutions for the continued improvement of CAR-T cell therapy.

Live Imaging of Immune Responses in Experimental Models of Multiple Sclerosis

Experimental autoimmune encephalomyelitis (EAE) is the most common animal model of multiple sclerosis (MS), a chronic inflammatory autoimmune disease of the central nervous system (CNS) characterized by multifocal perivascular infiltrates that predominantly comprise lymphocytes and macrophages. During EAE, autoreactive T cells first become active in the secondary lymphoid organs upon contact with antigen-presenting cells (APCs), and then gain access to CNS parenchyma, through a compromised blood–brain barrier, subsequently inducing inflammation and demyelination. Two-photon laser scanning microscopy (TPLSM) is an ideal tool for intravital imaging because of its low phototoxicity, deep tissue penetration, and high resolution. In the last decade, TPLSM has been used to visualize the behavior of T cells and their contact with APCs in the lymph nodes (LNs) and target tissues in several models of autoimmune diseases. The leptomeninges and cerebrospinal fluid represent particularly important points for T cell entry into the CNS and reactivation following contact with local APCs during the preclinical phase of EAE. In this review, we highlight recent findings concerning the pathogenesis of EAE and MS, emphasizing the use of TPLSM to characterize T cell activation in the LNs and CNS, as well as the mechanisms of tolerance induction. Furthermore, we discuss how advanced imaging unveils disease mechanisms and helps to identify novel therapeutic strategies to treat CNS autoimmunity and inflammation.

Ex vivo expanded regulatory T cells CD4+CD25+FoxP3+CD127Low develop strong immunosuppressive activity in patients with remitting-relapsing multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease characterized by defect in regulatory function of CD4⁺CD25⁺ T cells. We demonstrated difference in proportion of regulatory T cells CD4⁺CD25⁺FoxP3⁺CD127^low (Tregs) within the same patients' relapse and remission. Proportion of peripheral Tregs (pTregs) dropped almost two times in the relapse compare to remission. Levels of pTregs in patients' remission were lower than in healthy donors. Suppressive ability of pTregs was decreased in MS patients compared to healthy donors. Injections of expanded ex vivo autologous Tregs (eTregs) could be helpful in bringing up the level of Tregs in patients' blood. We developed a simple method for ex vivo expansion of autologous Tregs within a short period of time. The final pool of cells consisted of 90-95% eTregs. When we started the culture with 10-20 × 10⁶ CD4⁺ T cells, we yield 300-400 × 10⁶ eTregs in a week. Expression of FoxP3 and Helios was calculated by two methods. Expanded ex vivo patients' and donors' Tregs were characterized by increased from three to five times expression of FoxP3, as well as almost doubled Helios expression. Peripheral Tregs in MS patients have decreased demethylation of FoxP3 gene promoter in comparison with donors. On the contrary, eTregs showed stable up-regulated demethylation without difference between MS patients and donors. MS patients' and donors' eTregs have much more suppressive ability than pTregs. Our data showed that eTregs can be applied as immunotherapy for MS patients and other autoimmune diseases if further investigated.

Chimeric Antigen Receptor- and TCR-Modified T Cells Enter Main Street and Wall Street

The field of adoptive cell transfer (ACT) is currently comprised of chimeric Ag receptor (CAR)- and TCR-engineered T cells and has emerged from principles of basic immunology to paradigm-shifting clinical immunotherapy. ACT of T cells engineered to express artificial receptors that target cells of choice is an exciting new approach for cancer, and it holds equal promise for chronic infection and autoimmunity. Using principles of synthetic biology, advances in immunology, and genetic engineering have made it possible to generate human T cells that display desired specificities and enhanced functionalities. Clinical trials in patients with advanced B cell leukemias and lymphomas treated with CD19-specific CAR T cells have induced durable remissions in adults and children. The prospects for the widespread availability of engineered T cells have changed dramatically given the recent entry of the pharmaceutical industry to this arena. In this overview, we discuss some of the challenges and opportunities that face the field of ACT.

The mechanisms and applications of T cell vaccination for autoimmune diseases: a comprehensive review

Autoimmune diseases (ADs) are a spectrum of diseases originating from loss of immunologic self-tolerance and T cell abnormal autoreactivity, causing organ damage and death. However, the pathogenic mechanism of ADs remains unclear. The current treatments of ADs include nonsteroidal anti-inflammatory drugs (NSAIDS), antimalarials, corticosteroids, immunosuppressive drugs, and biological therapies. With the need to prevent side effects resulting from current treatments and acquire better clinical remission, developing a novel pharmaceutical treatment is extremely urgent. The concept of T cell vaccination (TCV) has been raised as the finding that immunization with attenuated autoreactive T cells is capable of inducing T cell-dependent inhibition of autoimmune responses. TCV may act as an approach to control unwanted adaptive immune response through eliminating the autoreactive T cells. Over the past decades, the effect of TCV has been justified in several animal models of autoimmune diseases including experimental autoimmune encephalomyelitis (EAE), murine autoimmune diabetes in nonobese diabetic (NOD) mice, collagen-induced arthritis (CIA), and so on. Meanwhile, clinical trials of TCV have confirmed the safety and efficacy in corresponding autoimmune diseases ranging from multiple sclerosis (MS) to systemic lupus erythematosus (SLE). This review aims to summarize the ongoing experimental and clinical trials and elucidate possible molecule mechanisms of TCV.

T cells in the control of organ-specific autoimmunity

Immune tolerance is critical to the avoidance of unwarranted immune responses against self antigens. Multiple, non-redundant checkpoints are in place to prevent such potentially deleterious autoimmune responses while preserving immunity integral to the fight against foreign pathogens. Nevertheless, a large and growing segment of the population is developing autoimmune diseases. Deciphering cellular and molecular pathways of immune tolerance is an important goal, with the expectation that understanding these pathways will lead to new clinical advances in the treatment of these devastating diseases. The vast majority of autoimmune diseases develop as a consequence of complex mechanisms that depend on genetic, epigenetic, molecular, cellular, and environmental elements and result in alterations in many different checkpoints of tolerance and ultimately in the breakdown of immune tolerance. The manifestations of this breakdown are harmful inflammatory responses in peripheral tissues driven by innate immunity and self antigen-specific pathogenic T and B cells. T cells play a central role in the regulation and initiation of these responses. In this Review we summarize our current understanding of the mechanisms involved in these fundamental checkpoints, the pathways that are defective in autoimmune diseases, and the therapeutic strategies being developed with the goal of restoring immune tolerance.

Selective immunotargeting of diabetogenic CD4 T cells by genetically redirected T cells

The key role played by islet-reactive CD8 and CD4 T cells in type 1 diabetes calls for new immunotherapies that target pathogenic T cells in a selective manner. We previously demonstrated that genetically linking the signalling portion of CD3-ζ onto the C-terminus of β2 -microglobulin and an autoantigenic peptide to its N-terminus converts MHC-I complexes into functional T-cell receptor-specific receptors. CD8 T cells expressing such receptors specifically killed diabetogenic CD8 T cells, blocked T-cell-induced diabetes in immunodeficient NOD.SCID mice and suppressed disease in wild-type NOD mice. Here we describe the immunotargeting of CD4 T cells by chimeric MHC-II receptors. To this end we chose the diabetogenic NOD CD4 T-cell clone BDC2.5, which recognizes the I-A(g7) -bound 1040-31 mimotope. We assembled several constructs encoding I-A(g7) α- and β-chains, the latter carrying mim or hen egg lysozyme peptide as control, each supplemented with CD3-ζ intracellular portion, either with or without its transmembrane domain. Following mRNA co-transfection of reporter B3Z T cells and mouse CD8 and CD4 T cells, these constructs triggered robust activation upon I-A(g7) cross-linking. A BDC2.5 T-cell hybridoma activated B3Z transfectants expressing the mimotope, but not the control peptide, in both configurations. Potent two-way activation was also evident with transgenic BDC2.5 CD4 T cells, but peptide-specific activation required the CD3-ζ transmembrane domain. Chimeric MHC-II/CD3-ζ complexes therefore allow the selective immunotargeting of islet-reactive CD4 T cells, which take part in the pathogenesis of type 1 diabetes.

Poly(ADP-ribose) polymerase-1 inhibitor modulates T regulatory and IL-17 cells in the prevention of adjuvant induced arthritis in mice model

Rheumatoid arthritis (RA) is one of the major autoimmune diseases of global prevalence. Irrespective of much research in RA disease, no drugs with capable safety profiles are yet available. Poly(ADP-ribose) polymerase-1 (PARP-1) synthesizes and transfers ADP ribose polymers to target proteins, and regulates DNA repair and genomic integrity maintenance. PARP-1 also plays a crucial role in the progression of the inflammatory response, and its inhibition confers protection in several models of inflammatory disorders. We investigated the possible anti-arthritic effects of the PARP-1 inhibitor 5-aminoisoquinolinone (5-AIQ) in a mouse model of adjuvant induced arthritis (AIA). In this study, we examined the effects of 5-AIQ on the key mediators of arthritic inflammation, namely, edema and arthritic score, T cell subsets, regulatory T (Treg) cells, IL-17A, GITR expressing cells, NF-kB p65, IkB-α and pro and anti-inflammatory mediators mRNA expression levels. PARP-1 inhibition 5-AIQ treatment significantly attenuated the severity of AIA, reduced the arthritis scores, a substantial reduction in the levels of T cell subsets, IL-17A, NF-kB p65, GITR expressing cells, and as well as the pro-inflammatory mediators. However, 5-AIQ significantly up-regulated the number of Tregs cells, IkB-α levels and mRNA expression of anti-inflammatory mediators. Our results suggest that treatment with 5-AIQ attenuated AIA in mice might offer a promising alternative/adjunct treatment for RA.

Regulatory T cells as immunotherapy

Regulatory T cells (Tregs) suppress exuberant immune system activation and promote immunologic tolerance. Because Tregs modulate both innate and adaptive immunity, the biomedical community has developed an intense interest in using Tregs for immunotherapy. Conditions that require clinical tolerance to improve outcomes – autoimmune disease, solid organ transplantation, and hematopoietic stem cell transplantation – may benefit from Treg immunotherapy. Investigators have designed ex vivo strategies to isolate, preserve, expand, and infuse Tregs. Protocols to manipulate Treg populations in vivo have also been considered. Barriers to clinically feasible Treg immunotherapy include Treg stability, off-cell effects, and demonstration of cell preparation purity and potency. Clinical trials involving Treg adoptive transfer to treat graft versus host disease preliminarily demonstrated the safety and efficacy of Treg immunotherapy in humans. Future work will need to confirm the safety of Treg immunotherapy and establish the efficacy of specific Treg subsets for the treatment of immune-mediated disease.

Peripheral blood CD8αα+CD11c+MHC-II+CD3- cells attenuate autoimmune glomerulonephritis in rats

In an anti-GBM glomerulonephritis (GN) model, GN-resistant Lewis rats naturally recover from early glomerular inflammation. Here we investigated recovery mechanisms for development of a potential immunotherapy for autoimmune GN. Our previous studies suggested that glomeruli-infiltrating leukocytes with a phenotype of CD8αα⁺CD11c⁺MHC⁻II⁺CD3⁻ (GIL CD8αα⁺ cells) were responsible for recovery through induction of T cell apoptosis. Now, we identified peripheral blood CD8αα⁺CD11c⁺MHC⁻II⁺CD3⁻ cells (PBMC CD8αα⁺CD3⁻ cells), which shared 9 markers with GIL CD8αα⁺ cells. Upon incubation, PBMC CD8αα⁺CD3⁻ cells displayed a morphology resembling that of dendritic cells. Similar to GIL CD8αα⁺ cells, PBMC CD8αα⁺CD3⁻ cells were capable of inducing T cell apoptosis in vitro. Hence, PBMC CD8αα⁺CD3⁻ cells were likely the precursor of GIL CD8αα⁺ cells. We next tested their potential in vivo function. PBMC CD8αα⁺CD3⁻ cells were able to infiltrate inflamed but not normal glomeruli. Isolated PBMC CD8αα⁺CD3⁻ cells of Lewis rats were transferred into GN-prone Wistar Kyoto rats at early inflammatory stage (day 17–25). When examined at day 45, both histopathology and BUN/serum creatinine level showed significantly attenuated GN in 80% of cell recipient Wistar Kyoto rats. Separate experiments verified infiltration of transferred Lewis PBMC CD8αα⁺CD3⁻ into the glomeruli, accompanied with apoptotic CD4⁺ T cells in the glomeruli of the recipient Wistar Kyoto rats. Thus, PBMC CD8αα⁺CD3⁻ cells of Lewis rats were able to terminate ongoing autoimmune inflammation in the glomeruli.

The imbalance of Th17/Treg in Chinese children with Henoch-Schonlein purpura

Interleukin 17 (IL-17)-producing T helper (Th17) cells and CD4(+)CD25(+) regulatory T (Treg) cells are two new T-cell subsets that are thought to be critically involved in mediating and regulating autoimmune responses. The imbalance of Th17/Treg cells has been implicated in a wide range of autoimmune disorders. The aim of our study was to determine whether the Th17/Treg balance was abnormal in children with Henoch-Schonlein Purpura (HSP). We examined twenty-three new-onset HSP patients and eighteen healthy children. The frequency of Th17 cells and the IL-17 concentration were higher in HSP patients than in healthy controls. The frequency of Treg cells and the interleukin 10 (IL-10) concentration were lower in HSP patients than in healthy controls. Compared to healthy controls, HSP patients exhibited an increase in the ratio of Th17/Treg. The Th17/Treg ratio was positively correlated with the erythrocyte sedimentation rate (ESR), kidney lesions and the clinical symptom of the presence of more than two organ systems with lesions. However, the ratio had no correlation with anti-streptolysin O (ASO) or complement 3 (C3) levels. These results indicate that a Th17/Treg imbalance exists in HSP, and it appears to be closely related to the disease onset.

[Use of regulatory T cells in cellular therapies in autoimmune diseases]

Self tolerance is dependent on regulatory T cells (Treg) which suppress effector T cells, avoiding autoimmunity. Functional and quantitative deficits of Treg have been reported in autoimmune diseases. A new therapeutic approach consisting in Treg adoptive transfer has proved to be efficient and safe in murine models. Two populations seem to be available for a clinical application: CD4(+)CD25(+)Foxp3(+) natural Treg derived from the thymus and induced regulatory T cells. First clinical trials have been applied to patients with autoimmune diseases. Classical treatments of autoimmune diseases are usually non-curative and require long-term administration. Treg cellular therapy may have a long-term effect and offers an alternative attractive approach.

CAR/FoxP3-engineered T regulatory cells target the CNS and suppress EAE upon intranasal delivery

BACKGROUND

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS). In the murine experimental autoimmune encephalomyelitis (EAE) model of MS, T regulatory (Treg) cell therapy has proved to be beneficial, but generation of stable CNS-targeting Tregs needs further development. Here, we propose gene engineering to achieve CNS-targeting Tregs from naïve CD4 cells and demonstrate their efficacy in the EAE model.

METHODS

CD4+ T cells were modified utilizing a lentiviral vector system to express a chimeric antigen receptor (CAR) targeting myelin oligodendrocyte glycoprotein (MOG) in trans with the murine FoxP3 gene that drives Treg differentiation. The cells were evaluated in vitro for suppressive capacity and in C57BL/6 mice to treat EAE. Cells were administered by intranasal (i.n.) cell delivery.

RESULTS

The engineered Tregs demonstrated suppressive capacity in vitro and could efficiently access various regions in the brain via i.n cell delivery. Clinical score 3 EAE mice were treated and the engineered Tregs suppressed ongoing encephalomyelitis as demonstrated by reduced disease symptoms as well as decreased IL-12 and IFNgamma mRNAs in brain tissue. Immunohistochemical markers for myelination (MBP) and reactive astrogliosis (GFAP) confirmed recovery in mice treated with engineered Tregs compared to controls. Symptom-free mice were rechallenged with a second EAE-inducing inoculum but remained healthy, demonstrating the sustained effect of engineered Tregs.

CONCLUSION

CNS-targeting Tregs delivered i.n. localized to the CNS and efficiently suppressed ongoing inflammation leading to diminished disease symptoms.

T helper 17 cells and regulatory T-cell imbalance in paediatric patients with asthma

Asthma is a chronic inflammatory disorder of the lung, which is thought to be determined by the balance between the T helper (Th)2 and Th1 responses. This study evaluated whether the balance between Th17 cells and regulatory T cells (T(reg)) was impaired in asthma patients. The proportion of peripheral blood Th17 cells of the total CD4(+) cell population in asthma patients was significantly higher than in controls (mean ± SD 0.72 ± 0.5% versus 0.31 ± 0.4%, respectively). The proportion of peripheral T(reg) cells in asthma patients was significantly lower than in controls (mean ± SD 12.1 ± 4.6% versus 27.2 ± 7.5%, respectively). Analysis of mRNA generally confirmed the flow cytometry data, suggesting that the changes in cytokine levels were mediated at the transcription level. In paediatric asthma patients, the CD4(+) T-cell phenotype was skewed toward the Th17 phenotype, suggesting that a Th17/T(reg) functional imbalance plays a role in asthma.

Th17/Treg imbalance in adult patients with minimal change nephrotic syndrome

To determine whether Th17/Treg balance was abnormal in adult patients with minimal change nephrotic syndrome (MCNS), we studied 25 patients with new-onset MCNS and 20 normal persons. The results showed that MCNS patients exhibited a significant increase in Th17 number, Th17-related cytokines (IL-17 and IL-23), and transcription factor (RORγt) levels, as well as an obvious decrease in Treg number, Treg-related cytokines (TGF-β1 and IL-10), and transcription factor (Foxp3) levels. The Th17/Treg ratios increased along with increased proteinuria and decreased albumin levels in patients with MCNS. IL-17 protein expression was also detected in the renal biopsy tissue of MCNS patients, particularly in patients with acute renal failure. Further, Th17/Treg balance returned to normal after effective corticosteroids therapy in 16 MCNS patients. These results indicated that Th17/Treg imbalance existed in MCNS patients, suggesting a potential role of Th17/Treg imbalance in the pathogenesis of MCNS.

Potent antirheumatic activity of a new DNA vaccine targeted to B7-2/CD28 costimulatory signaling pathway in autoimmune arthritis

Rheumatoid arthritis is a proinflammatory autoimmune disease attributed to failure of both CD4(+)CD25(+) regulatory T (Tr) and CD8(+)CD28(-) suppressor T (Ts) cells to control autoreactive CD4(+)CD28(+) Th1 (Th1) and autoantibody-producing B cells. Here we show a single intramuscular injection of our novel targeted DNA vaccine encoding Pseudomonas exotoxin A and costimulatory molecule B7-2 without autoantigens in a collagen-induced arthritis model simultaneously increased Tr and Ts cells and selectively decreased autoreactive Th1 cells. The vaccine induced a shift from Th1 to Th2 and Th3 cellular and cytokine profiles and a decrease in CD4(+)/CD8(+) cell ratios. Importantly, the vaccine showed potent antirheumatic activity by clinical and other examinations such as X-ray, histopathology, and anti-type II collagen IgG levels and was comparable to methotrexate, the current "gold standard" treatment. As an effective stimulator of both Tr and Ts cells and a specific suppressor of autoreactive Th1 cells, this vaccine is a promising therapeutic approach for rheumatoid arthritis.

Suppression of encephalitogenic T-cell responses by cilostazol is associated with upregulation of regulatory T cells

Cilostazol is a specific phosphodiesterase III inhibitor. Recent data show that cilostazol has anti-inflammatory effects and administration of cilostazol ameliorates experimental autoimmune encephalomyelitis (EAE). In this study, we used a mouse EAE model to explore the role of cilostazol in Th1 and Th17 cell-mediated immune responses. We found that cilostazol suppressed mitogen or antigen-induced T-cell responses and Th17 cell differentiation in vitro, which correlated with enhanced Treg-cell responses. Beginning of oral administration of cilostazol at the onset of EAE significantly inhibited encephalitogenic T cells, reduced the levels of inflammatory cytokines in the central nervous system, and ameliorated the severity of EAE. Moreover, administration of cilostazol markedly enhanced Treg-cell response in vivo. Cilostazol, therefore, may exert its therapeutic effects through upregulation of Treg-cell activity.

Brain ingress of regulatory T cells in a murine model of HIV-1 encephalitis

CD4+CD25+ regulatory T cells (Treg) transform the HIV-1 infected macrophage from a neurotoxic to a neuroprotective phenotype. This was demonstrated previously in a murine model of HIV-1 encephalitis induced by intracranial injection of HIV-1/vesicular stomatitis virus-infected bone marrow macrophages. In this report, relationships between Treg ingress of end organ tissues, notably the brain, and neuroprotection were investigated. Treg from EGFP-transgenic donor mice were expanded, labeled with indium-111, and adoptively transferred. Treg distribution was assayed by single photon emission computed tomography and immunohistochemistry. Treg readily migrated across the blood brain barrier and were retained within virus-induced neuroinflammatory sites. In non-inflamed peripheral tissues (liver and spleen) Treg were depleted. These observations demonstrate that Treg migrate to sites of inflammation where they modulate immune responses.