Therapeutic potential of TGF-β-induced CD4(+) Foxp3(+) regulatory T cells in autoimmune diseases

Roles of IRF4 in various immune cells in systemic lupus erythematosus

Interferon regulatory factor 4 (IRF4) is a member of IRF family of transcription factors which mainly regulates the transcription of IFN. IRF4 is restrictively expressed in immune cells such as T and B cells, macrophages, as well as DC. It is essential for the development and function of these cells. Since these cells take part in the homeostasis of the immune system and dysfunction of them contributes to the initiation and progress of systemic lupus erythematosus (SLE), the roles of IRF4 in the SLE development becomes an important topic. Here we systemically discuss the biological characteristics of IRF4 in various immune cells and analyze the pathologic effects of IRF4 alteration in SLE and the potential targeting therapeutics of SLE.

Comparison of Low-Dose Interleukin 2 Therapy in Conjunction With Standard Therapy in Patients With Systemic Lupus Erythematosus vs Rheumatoid Arthritis: A Systematic Review

This systematic review aims to compare the efficacy and safety of a novel immunotherapy with low-dose interleukin 2 (IL2) across two of the most prevalent autoimmune diseases i.e. systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). Contemporary therapeutic practices have not been able to achieve complete remission from these autoimmune disorders. In contrast, low-dose IL2 has shown promise in achieving this therapeutic goal via inducing self-tolerance in patients with autoimmune diseases; however, due to variable irregularities among autoimmune processes of variable diseases, the benefit of low-dose IL2 could not be determined among different autoimmune diseases. Therefore, we conducted a study to compare low-dose IL2 therapy effects on SLE and RA. We systematically screened four databases: PubMed, Medical Literature Analysis and Retrieval System Online (MEDLINE), PubMed Central (PMC), and Google Scholar. Inclusion and exclusion criteria were implemented. Quality appraisal of studies chosen for the review was done using the Cochrane Risk-of-Bias (RoB) assessment tool for randomized controlled trials, and the Newcastle-Ottawa Scale (NOS) and JBI critical appraisal tool for non-randomized clinical trials. Information was gathered from seven articles: three randomized controlled trials and four non-randomized clinical trials. Our review concluded that low-dose IL2 therapy in conjunction with respective standard therapies for SLE and RA has a higher efficacy and safety profile as compared to standard therapy alone and the therapeutic effects were comparable in both SLE and RA patients treated with low-dose IL2; however, this novel intervention does not seem to have a significant corrective effect on the biomarkers of RA as it does for SLE biomarkers.

Cell-based therapies for the treatment of rheumatoid arthritis

Autoimmune diseases, including rheumatoid arthritis that is the most prevalent rheumatic autoimmune disorder, affect autologous connective tissues caused by the breakdown of the self-tolerance mechanisms of the immune system. During the last two decades, cell-based therapy, including stem cells and none-stem cells has been increasingly considered as a therapeutic option in various diseases. This is partly due to the unique properties of stem cells that divide and differentiate from the specialized cells in the damaged tissue. Moreover, stem cells and none-stem cells, impose immunomodulatory properties affecting the diseases caused by immunological abnormalities such as rheumatic autoimmune disorders. In the present review, the efficacy of cell-based therapy with four main types of stem cells, including mesenchymal stem cells, hematopoietic stem cells, embryonic stem cells, and human amniotic membrane cells, as well as none-stem cells, including regulatory T cells, chimeric antigen receptor T cells, and tolerogenic dendritic cells will be evaluated. Moreover, other related issues, including safety, changes in immunological parameters, suitable choice of stem cell and none-stem cell origin, conditioning regimen, limitations, and complications will be discussed.

The role of transforming growth factor beta in thyroid autoimmunity: current knowledge and future perspectives

The complex mechanisms, which are related to the pathophysiology and the development of autoimmune thyroid diseases, involve transforming growth factor beta (TGF-β) and its interplay with the immune system. The aim of this review is to examine the role of TGF-β regarding thyroid autoimmunity and explore the potent role of this molecule either as a diagnostic or prognostic marker or a therapeutic target regarding autoimmune thyroid diseases. TGF-β is clearly a master regulator of the immune response, exerting either inhibitory or facilitatory effects on cells of the immune system. Thus, this molecule is involved in the pathogenesis and development of autoimmune thyroid diseases. Recent research has revealed the involvement of TGF-β in the pathophysiology of autoimmune thyroid diseases. The role of TGF-β in the development of autoimmune thyroid diseases varies, depending on its concentrations, the type of the activated TGF-β signalling pathway, the genetic predisposition of the patient and the pathophysiologic stage of the disease. TGF-β could emerge as a useful diagnostic or prognostic marker for the evolution of thyroid autoimmunity. Promising perspectives for the effective therapeutic use of TGF-β regarding thyroid autoimmunity exist. The main treatment approaches incorporate either enhancement of the immunosuppressive role of TGF-β or inhibition of its facilitatory role in the autoimmune thyroid diseases. Further research towards deeper understanding of TGF-β physiology and clinical application of its possible therapeutic role regarding thyroid autoimmunity is needed.

Emerging therapeutic potential of regulatory T (Treg) cells for rheumatoid arthritis: New insights and challenges

Rheumatoid arthritis (RA) is an autoimmune-related disorder characterized by chronic inflammation. Although the etiopathogenesis of RA still remains to be clarified, it is supposed that the breakdown of immune self-tolerance may contribute to the development of RA. Thus, restoring of immune tolerance at the site of inflammation is the ultimate goal of RA treatment. Regulatory T cells (Treg cells) are the main suppressive cells that maintain tolerance and inhibit immunity against auto-antigen. Of note, recent studies demonstrated the efficacy of adoptive transfer of Treg cells in the modulation of the unwanted immune response, which makes them an ideal candidate to maintain immune homeostasis and restore antigen-specific tolerance in the case of RA and other autoimmune diseases. This review intends to submit recent finding of Treg cells-based therapies in RA with a focus on strategies applied to improve the therapeutic value of Treg cells to restore immune tolerance.

CAR-T Regulatory (CAR-Treg) Cells: Engineering and Applications

Regulatory T cells are critical for maintaining immune tolerance. Recent studies have confirmed their therapeutic suppressive potential to modulate immune responses in organ transplant and autoimmune diseases. However, the unknown and nonspecific antigen recognition of polyclonal Tregs has impaired their therapeutic potency in initial clinical findings. To address this limitation, antigen specificity can be conferred to Tregs by engineering the expression of transgenic T-cell receptor (TCR) or chimeric antigen receptor (CAR). In contrast to TCR Tregs, CAR Tregs are major histocompatibility complex (MHC) independent and less dependent on interleukin-2 (IL-2). Furthermore, CAR Tregs maintain Treg phenotype and function, home to the target tissue and show enhanced suppressive efficacy compared to polyclonal Tregs. Additional development of engineered CAR Tregs is needed to increase Tregs’ suppressive function and stability, prevent CAR Treg exhaustion, and assess their safety profile. Further understanding of Tregs therapeutic potential will be necessary before moving to broader clinical applications. Here, we summarize recent studies utilizing CAR Tregs in modulating immune responses in autoimmune diseases, transplantation, and gene therapy and future clinical applications.

TGF-β-induced CD4+ FoxP3+ regulatory T cell-derived extracellular vesicles modulate Notch1 signaling through miR-449a and prevent collagen-induced arthritis in a murine model

CD4⁺FOXP3⁺ Treg cells are central to the maintenance of self-tolerance and can be defective in autoimmunity. In autoimmune rheumatic diseases, dysfunctional self-tolerance, is to a large extent, caused by insufficient Treg-cell activity. Although nTregs have therapeutic effects in vivo, their relative scarcity and slow rate of in vitro expansion hinder the application of nTreg therapy. It was previously reported that EVs contribute significantly to the suppressive function of FOXP3⁺ Treg cells. Considering that the stability and plasticity of nTregs remain major challenges in vivo, we established EVs derived from in vitro TGF-β-induced Treg cells (iTreg-EVs) and assessed their functions in a murine model of autoimmune arthritis. The results demonstrated that iTreg-EVs preferentially homed to the pathological joint and efficiently prevented the imbalance in Th17/Treg cells in arthritic mice. Furthermore, we found that miR-449a-5p mediated Notch1 expression modulation and that miR-449a-5p knockdown abolished the effects of iTreg-EVs on effector T cells and regulatory T cells in vitro and in vivo. Taken together, our results show that iTreg-EVs control the inflammatory responses of recipient T cells through miR-449a-5p-dependent modulation of Notch1 and ameliorate the development and severity of arthritis, which may provide a potential cell-free strategy based on manipulating iTreg-EVs to prevent autoimmune arthritis.

MS-Based HLA-II Peptidomics Combined With Multiomics Will Aid the Development of Future Immunotherapies

Immunotherapies have emerged to treat diseases by selectively modulating a patient's immune response. Although the roles of T and B cells in adaptive immunity have been well studied, it remains difficult to select targets for immunotherapeutic strategies. Because human leukocyte antigen class II (HLA-II) peptides activate CD4+ T cells and regulate B cell activation, proliferation, and differentiation, these peptide antigens represent a class of potential immunotherapy targets and biomarkers. To better understand the molecular basis of how HLA-II antigen presentation is involved in disease progression and treatment, systematic HLA-II peptidomics combined with multiomic analyses of diverse cell types in healthy and diseased states is required. For this reason, MS-based innovations that facilitate investigations into the interplay between disease pathologies and the presentation of HLA-II peptides to CD4+ T cells will aid in the development of patient-focused immunotherapies.

Function and Role of Regulatory T Cells in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a systemic and heterogeneous autoimmune disease with symmetrical polyarthritis as its critical clinical manifestation. The basic cause of autoimmune diseases is the loss of tolerance to self or harmless antigens. The loss or functional deficiency of key immune cells, regulatory T (Treg) cells, has been confirmed in human autoimmune diseases. The pathogenesis of RA is complex, and the dysfunction of Tregs is one of the proposed mechanisms underlying the breakdown of self-tolerance leading to the progression of RA. Treg cells are a vital component of peripheral immune tolerance, and the transcription factor Foxp3 plays a major immunosuppressive role. Clinical treatment for RA mainly utilizes drugs to alleviate the progression of disease and relieve disease activity, and the ideal treatment strategy should be to re-induce self-tolerance before obvious tissue injury. Treg cells are one of the ideal options. This review will introduce the classification, mechanism of action, and characteristics of Treg cells in RA, which provides insights into clinical RA treatment.

Regulatory T Cells: Concept, Classification, Phenotype, and Biological Characteristics

Regulatory T cells (Treg) play an indispensable role in maintaining the body's immune nonresponse to self-antigens and suppressing the body's unwarranted and potentially harmful immune responses. Their absence, reduction, dysfunction, transformation, and instability can lead to numerous autoimmune diseases. There are several distinct subtypes of the Treg cells, although they share certain biological characteristics and have unique phenotypes with different regulatory functions, as well as mechanistic abilities. In this book chapter, we introduce the latest advances in Treg cell subtypes pertaining to classification, phenotype, biological characteristics, and mechanisms. We also highlight the relationship between Treg cells and various diseases, including autoimmune, infectious, as well as tumors and organ transplants.

Adoptive Treg cell-based immunotherapy: Frontier therapeutic aspects in rheumatoid arthritis

The major current focus on treating rheumatoid arthritis is to put an end to long-term treatments and instead, specifically block widespread immunosuppression by developing antigen-specific tolerance, while also permitting an intact immune response toward other antigens to occur. There have been promising preclinical findings regarding adoptive Treg cells immunotherapy with a critically responsible function in the prevention of autoimmunity, tissue repair and regeneration, which make them an attractive candidate to develop effective therapeutic approaches to achieve this interesting concept in many human immune-mediated diseases, such as rheumatoid arthritis. Ex vivo or invivo manipulation protocols are not only utilized to correct Treg cells defect, but also to benefit from their specific immunosuppressive properties by identifying specific antigens that are expressed in the inflamedjoint. The methods able to address these deficiencies can be considered as a target for immunity interventions to restore appropriate immune function.

Advances on the role of the deleted in breast cancer (DBC1) in cancer and autoimmune diseases

DBC1 (deleted in breast cancer 1) is a human nuclear protein that modulates the activities of various proteins. Most of the research on DBC1 has focused on metabolism and epigenetics because it is a crucial endogenic inhibitor of deacetylase Sirtuin1 (SIRT1). In this review, we have discussed and summarized the new advances in DBC1 research, mostly focusing on its structure, regulatory function, and significance in cancer and autoimmune diseases.

CD4+FOXP3+ T Cells in Rheumatoid Arthritis Bone Marrow Are Partially Impaired

There is evolving evidence that dysregulation of immune homeostasis in the bone marrow (BM) adjacent to the inflamed joints is involved in the pathogenesis of. In this study, we are addressing the phenotype and function of regulatory T cells (Tregs) residing in the BM of patients with rheumatoid arthritis (RA) and osteoarthritis (OA). BM and peripheral blood samples were obtained from RA and OA patients undergoing hip replacement surgery. The number and phenotype of Tregs were analyzed by flow cytometry and immunohistochemistry. The function of Tregs was investigated ex vivo, addressing their suppressive activity on effector T cells. [³H]-Thymidine incorporation assay and specific enzyme-linked immunosorbent assay were used for quantification of cell proliferation and pro-inflammatory (TNF, IFN-γ) cytokine release, respectively. Significantly lower numbers of CD4⁺FOXP3⁺ T cells were found in the BM of patients with RA compared to control patients with OA. High expression of CD127 (IL-7α receptor) and relatively low expression of CXCR4 (receptor for stromal cell-derived factor CXCL12) are characteristics of the CD4⁺FOXP3⁺ cells residing in the BM of RA patients. The BM-resident Tregs of RA patients demonstrated a limited suppressive activity on the investigated immune response. Our results indicate that the reduced number and impaired functional properties of CD4⁺FOXP3⁺ T cells present in the BM of RA patients may favor the inflammatory process, which is observed in RA BM.

Reprogramming of Th1 cells into regulatory T cells through rewiring of the metabolic status

T helper type 1 (Th1) cells form one of the most stable CD4 T-cell subsets, and direct conversion of fully differentiated Th1 to regulatory T (Treg) cells has been poorly investigated. Here, we established a culture method for inducing Foxp3 from Th1 cells of mice and humans. This is achieved simply by resting Th1 cells without T-cell receptor ligation before stimulation in the presence of transforming growth factor-beta (TGF-β). We named the resulting Th1-derived Foxp3+ cells Th1reg cells. Mouse Th1reg cells showed an inducible Treg-like phenotype and suppressive ability both in vitro and in vivo. Th1reg cells could also be induced from in vivo-developed mouse Th1 cells. Unexpectedly, the resting process enabled Foxp3 expression not through epigenetic changes at the locus, but through metabolic change resulting from reduced mammalian target of rapamycin complex 1 (mTORC1) activity. mTORC1 suppressed TGF-β-induced phosphorylation of Smad2/3 in Th1 cells, which was restored in rested cells. Our study warrants future research aiming at development of immunotherapy with Th1reg cells.

Dihydrotestosterone regulates oxidative stress and immunosuppressive cytokines in a female BALB/c mouse model of Graves' disease

Background: Graves' disease (GD) is an autoimmune disease that affects more women than men. In our previous study, a potent bioactive androgen, 5α-dihydrotestosterone (DHT) showed a protective effect against GD in female BALB/c mice. Evidence indicates that abnormal oxidative stress and immunosuppressive cytokines (TGF-β, IL-35) play critical roles in the pathogenesis and development of GD. The purpose of this research is to measure these cytokines and oxidative stress markers to explore potential protective mechanisms of DHT in a BALB/c mouse model of GD. Methods: GD was induced in female BALB/c mice by intramuscular injection of an adenovirus expressing the A-subunit of the TSH receptor (Ad-TSHR289). DHT or a matching placebo was injected every 3 days. Mice were sacrificed four weeks after the third virus immunization to obtain blood, thyroid and spleen for further analysis. Results: Thyroid hormones were significantly reduced in DHT treated GD mice. In addition, DHT attenuated thyroid oxidative injuries in GD mice, as shown by decreased total antioxidation capability (TAOC), superoxide dismutase (SOD) and the level of malondialdehyde (MDA). The levels of immunosuppressive cytokines (TGF-β, IL-35) in DHT group were significant higher compared with the GD group. Conclusions: The results demonstrated that DHT could reduce the severity of GD in female BALB/c mice by regulating oxidative stress. The upregulation of immunosuppressive cytokines might be another important protective mechanism.

Helminths protect against type 1 diabetes: effects and mechanisms

Type 1 diabetes (T1D) is an autoimmune disease in which cells of the immune system destroy pancreatic β cells, which secrete insulin. The high prevalence of T1D in developed societies may be explained by environmental changes, including lower exposure to helminths. Indeed, infection by helminths such as Schistosoma, Filaria, and Heligmosomoides polygyrus and their by-products has been reported to ameliorate or prevent the development of T1D in human and animal models. Helminths can trigger distinct immune regulatory pathways, often involving adaptive immune cells that include T helper 2 (Th2) cells and regulatory T cells (Tregs) and innate immune cells that include dendritic cells, macrophages, and invariant natural killer T cells, which may act synergistically to induce Tregs in a Toll-like receptor-dependent manner. Cytokines such as interleukin (IL)-4, IL-10, and transforming growth factor (TGF)-β also play an important role in protection from T1D. Herein, we provide a comprehensive review of the effects and mechanisms underlying protection against T1D by helminths.

Regulatory T cells and CD20+ B cells in pediatric very severe aplastic anemia: possible clinical markers for evaluating the therapeutic efficacy and prognosis

OBJECTIVES

To investigate the immune status of children with very severe aplastic anemia (VSAA), and evaluate the frequencies of CD20⁺ B cells and Regulatory T cells (Tregs) as potential markers for evaluating the therapeutic efficacy and prognosis.

METHODS

We systematically analyzed CD20⁺ B cells and Tregs using Flow Cytometry in 36 children with VSAA (14 newly diagnosed cases and 22 cases in remission after therapy with HDIVIG + r-ATG + CSA).

RESULTS

In newly diagnosed VSAA patients, the percentage of CD20⁺ B cells was higher than that in healthy children (P < .01), whereas the percentage of Tregs was lower than that in healthy children (P < .001). After treatment with HDIVIG + r-ATG + CSA, the percentage of CD20⁺ B cells in peripheral blood was decreased obviously, and the percentage of Tregs was significantly increased.

CONCLUSION

There is a moderate negative correlation between the percentage of Tregs and CD20⁺ B cells in our study. Our results shed light on the roles of Tregs and CD20⁺ B cells as therapeutic efficacy and prognostic markers of pediatric VSAA. Moreover, the mechanism underlying the decrease of blood Tregs and increase of CD20⁺ B cells in pediatric VSAA patients have been discussed, indicating that Tregs may suppress B cell responses.

Targeting IL-2: an unexpected effect in treating immunological diseases

Regulatory T cells (Treg) play a crucial role in maintaining immune homeostasis since Treg dysfunction in both animals and humans is associated with multi-organ autoimmune and inflammatory disease. While IL-2 is generally considered to promote T-cell proliferation and enhance effector T-cell function, recent studies have demonstrated that treatments that utilize low-dose IL-2 unexpectedly induce immune tolerance and promote Treg development resulting in the suppression of unwanted immune responses and eventually leading to treatment of some autoimmune disorders. In the present review, we discuss the biology of IL-2 and its signaling to help define the key role played by IL-2 in the development and function of Treg cells. We also summarize proof-of-concept clinical trials which have shown that low-dose IL-2 can control autoimmune diseases safely and effectively by specifically expanding and activating Treg. However, future studies will be needed to validate a better and safer dosing strategy for low-dose IL-2 treatments utilizing well-controlled clinical trials. More studies will also be needed to validate the appropriate dose of IL-2/anti-cytokine or IL-2/anti-IL-2 complex in the experimental animal models before moving to the clinic.

Immunosuppressive Effect of B7-H4 Pathway in a Murine Systemic Lupus Erythematosus Model

B7-H4, one of the co-stimulatory molecules of the B7 family, has been shown to play an important role in negatively regulating the adaptive immune response by inhibiting the proliferation, activation, and cytokine production of T cells. In this study, we investigate the role of B7-H4 in development of systemic lupus erythematosus (SLE). We investigated a murine model of SLE using transfer of bone marrow-derived dendritic cells (BMDCs) that were incubated with activated syngeneic lymphocyte-derived DNA. The recipient mouse produced anti-ds-DNA antibodies as well as displayed splenomegaly and lymphadenopathy as shown by significantly increased weights, and the kidneys showed lupus-like pathological changes include urine protein and glomerulonephritis with hyperplasia in glomeruli and increased mesangial cells and vasculitis with perivascular cell infiltration, glomerular deposition of IgG and complement C3. We showed that B7-H4 deficiency in BMDCs could cause greater production of anti-ds-DNA antibodies in transferred mice, and the lymph tissue swelling and the kidney lesions were also exacerbated with B7-H4 deficiency. Treatment with a B7-H4 antagonist antibody also aggravated the lupus model. Conversely, B7-H4 Ig alleviated the lupus manifestations. Therefore, we conclude that B7-H4 is a negative check point for the development of SLE in this murine model. These results suggest that this approach may have a clinical potential in treating human SLE.

Caerulomycin A suppresses the differentiation of naïve T cells and alleviates the symptoms of experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is a highly detrimental autoimmune disease of the central nervous system. There is no cure for it but the treatment typically focuses on subsiding severity and recurrence of the disease. Experimental autoimmune encephalomyelitis (EAE) is an animal model of MS. It is characterized by frequent relapses due to the generation of memory T cells. Caerulomycin A (CaeA) is known to suppress the Th1 cells, Th2 cells, and Th17 cells. Interestingly, it enhances the generation of regulatory T cells (Tregs). Th1 cells and Th17 cells are known to aggravate EAE, whereas Tregs suppress the disease symptoms. Consequently, in the current study we evaluated the influence of CaeA on EAE. Intriguingly, we observed by whole body imaging that CaeA regressed the clinical symptoms of EAE. Further, there was reduction in the pool of Th1 cells, Th17 cells, and CD8 T cells. The mechanism involved in suppressing the EAE symptoms was due to the inhibition in the generation of effector and central memory T cells and induction of the expansion of Tregs. In essence, these findings implicate that CaeA may be considered as a potent future immunosuppressive drug.

Modification of anti-tumor immunity by tolerogenic dendritic cells

Immunosuppressive functions of glucocorticoids (GC) can be mediated via various mechanisms, including the modulation of dendritic cells (DC). Our study investigates the effects of tolerogenic GC-treated DCs on NK and T cell anti-tumor responses in OT-1/Rag^-/- mice, expressing a transgenic TCR in CD8⁺ T cells. The effects caused by GC-treated DCs were compared to the responses to immunogenic, CpG-activated DCs. The effects of DCs on anti-tumor immune responses were analyzed using the EG7 tumor model, where the tumor cells express the peptide epitope recognized by OT-1 T cells. We observed that immunization with CpG and peptide-treated DCs protected against tumor growth by activation of NK cell response. Also, immunogenic DCs induced the expansion of cytotoxic CD8⁺OT-1 cells, expressing activation markers CD44 and CD69 and producing IFNγ. In contrast, the peptide and GC-treated DCs in OT-1 mice increased the numbers of immature Mac-1⁺CD27^- NK cells as well as Foxp3⁺ and IL-10 secreting CD8⁺OT-1 cells with suppressive properties. We conclude that the generation of tolerogenic DCs is one of many immunosuppressive mechanisms that can be induced by GC. Our study demonstrated that tolerogenic DCs modify anti-tumor immune response by suppressing NK cell activity and stimulating the formation of IL-10-secreting CD8⁺ Tregs.

Adoptive Cell Therapy of Induced Regulatory T Cells Expanded by Tolerogenic Dendritic Cells on Murine Autoimmune Arthritis

Objective

Tolerogenic dendritic cells (tDCs) can expand TGF-β-induced regulatory T cells (iTregs); however, the therapeutic utility of these expanded iTregs in autoimmune diseases remains unknown. We sought to determine the properties of iTregs expanded by mature tolerogenic dendritic cells (iTreg_mtDC) in vitro and explore their potential to ameliorate collagen-induced arthritis (CIA) in a mouse model.

Methods

After induction by TGF-β and expansion by mature tDCs (mtDCs), the phenotype and proliferation of iTreg_mtDC were assessed by flow cytometry. The ability of iTregs and iTreg_mtDC to inhibit CD4⁺ T cell proliferation and suppress Th17 cell differentiation was compared. Following adoptive transfer of iTregs and iTreg_mtDC to mice with CIA, the clinical and histopathologic scores, serum levels of IFN-γ, TNF-α, IL-17, IL-6, IL-10, TGF-β and anti-CII antibodies, and the distribution of the CD4⁺ Th subset were assessed.

Results

Compared with iTregs, iTreg_mtDC expressed higher levels of Foxp3 and suppressed CD4⁺ T cell proliferation and Th17 cell differentiation to a greater extent. In vivo, iTreg_mtDC reduced the severity and progression of CIA more significantly than iTregs, which was associated with a modulated inflammatory cytokine profile, reduced anti-CII IgG levels, and polarized Treg/Th17 balance.

Conclusion

This study highlights the potential therapeutic utility of iTreg_mtDC in autoimmune arthritis and should facilitate the future design of iTreg immunotherapeutic strategies.

Interleukin-35: a Potential Therapeutic Agent for Autoimmune Diseases

Autoimmune diseases contain a large number of pathologies characterized by various factors that contribute to a breakdown in self-tolerance. Cytokine-mediated immunity plays an essential role in the pathogenesis of varieties of autoimmune diseases. Recent studies reveal that interleukin-35 (IL-35), a newly identified cytokine of IL-12 family, is implicated in the pathogenesis of autoimmune diseases, such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), systemic sclerosis (SSc), etc. In this review, we will discuss the biological features of IL-35 and summarize recent advances in the role of IL-35 in the development and pathogenesis of autoimmune diseases; the discoveries gained from these findings might translate into future therapies for these diseases.

Progranulin Inhibits Human T Lymphocyte Proliferation by Inducing the Formation of Regulatory T Lymphocytes

We have examined the effect of progranulin (PGRN) on human T cell proliferation and its underlying mechanism. We show that PGRN inhibits the PHA-induced multiplication of T lymphocytes. It increases the number of iTregs when T lymphocytes are activated by PHA but does not do so in the absence of PHA. PGRN-mediated inhibition of T lymphocyte proliferation, as well as the induction of iTregs, was completely reversed by a TGF-β inhibitor or a Treg inhibitor. PGRN induced TGF-β secretion in the presence of PHA whereas it did not in the absence of PHA. Our findings indicate that PGRN suppresses T lymphocyte proliferation by enhancing the formation of iTregs from activated T lymphocytes in response to TGF-β.

Diversity of immune cell types in multiple sclerosis and its animal model: Pathological and therapeutic implications

Multiple sclerosis (MS) is an inflammatory, demyelinating disease of the central nervous system with an autoimmune attack on the components of the myelin sheath and axons. The etiology of the disease remains largely unknown, but it is commonly acknowledged that the development of MS probably results from the interaction of environmental factors in conjunction with a genetic predisposition. Current therapeutic approaches can only ameliorate the clinical symptoms or reduce the frequency of relapse in MS. Most drugs used in this disease broadly suppress the functions of immune effector cells, which can result in serious side effects. Thus, new therapeutic methods resulting in greater efficacy and lower toxicity are needed. Toward this end, cell-based therapies are of increasing interest in the treatment of MS. Several immunoregulatory cell types, including regulatory T cells, regulatory B cells, M2 macrophages, tolerogenic dendritic cells, and stem cells, have been developed as novel therapeutic tools for the treatment of MS. In this Review, we summarize studies on the application of these cell populations for the treatment of MS and its animal model, experimental autoimmune encephalomyelitis, and call for further research on applications and mechanisms by which these cells act in the treatment of MS. © 2017 The Authors Journal of Neuroscience Research Published by Wiley Periodicals, Inc.

The Critical Role of Induced CD4+ FoxP3+ Regulatory Cells in Suppression of Interleukin-17 Production and Attenuation of Mouse Orthotopic Lung Allograft Rejection

BACKGROUND

Lung transplantation is the only definitive therapy for many forms of end-stage lung disease. Studies have demonstrated the critical role of interleukin (IL)-17 in the development of lung rejection. Regulatory T cells (Tregs) are essential for the establishment and maintenance of immune tolerance.

METHODS

We established mouse orthotopic lung transplantation models to investigate the importance of IL-17 and IL-17-producing cell types in acute lung allograft rejection and the efficacy of the adoptive transfer of induced Tregs (iTregs) in attenuating pathologic lesions of lung allografts.

RESULTS

We found that the IL-17 produced by Th17 cells and γδ T cells might make the primary contributions to the progression of acute lung allograft rejection. Interleukin-17 deficiency decreased lung allograft lesions. Exogenous iTregs maintained their FoxP3 expression levels in lung allograft recipients. Induced Tregs therapy downregulated the expressions of Th17 and IL-17 γδ T cells and increased IL-10 production in the mouse orthotopic lung transplantation models. Moreover, the adoptive transfer of iTregs prolonged the survivals of the lung allografts and attenuated the progression of acute rejection.

CONCLUSION

These data suggested that the adoptive transfer of iTregs could suppress the Th17 cells and IL-17 γδ cells of the recipients, decrease the expression of IL-17, and attenuate the pathology of acute lung allograft rejection. Exogenous iTregs upregulated immunosuppressive factors, such as IL-10 and suppressed IL-17-producing cells, which was one of the pathways to play a role in protecting lung allografts.

Regulatory T Cells and Their Role in Animal Disease

In humans and mouse models, Foxp3(+) regulatory T cells are known to control all aspects of immune responses. However, only limited information exists on these cells' role in diseases of other animals. In this review, we cover the most important features and different types of regulatory T cells, which include those that are thymus-derived and peripherally induced, the mechanisms by which they control immune responses by targeting effector T cells and antigen-presenting cells, and most important, their role in animal health and diseases including cancer, infections, and other conditions such as hypersensitivities and autoimmunity. Although the literature regarding regulatory T cells in domestic animal species is still limited, multiple articles have recently emerged and are discussed. Moreover, we also discuss the evidence suggesting that regulatory T cells might limit the magnitude of effector responses, which can have either a positive or negative result, depending on the context of animal and human disease. In addition, the issue of plasticity is discussed because plasticity in regulatory T cells can result in the loss of their protective function in some microenvironments during disease. Lastly, the manipulation of regulatory T cells is discussed in assessing the possibility of their use as a treatment in the future.

CD4(+)CD25(-)Foxp3(+) T cells play a role in tuberculous hydrothorax rather than malignant hydrothorax

BACKGROUND

Foxp3(+) T cells regulate inflammation and tumorigenesis. However, little is known about the role of different subsets of Foxp3(+) T cells in malignant or tuberculous hydrothorax.

METHODS

The numbers of CD4(+)CD25(+)Foxp3(+), CD4(+)CD25(-)Foxp3(+) T cells and the levels of some inflammatory cytokines in patients with tuberculous hydrothorax, malignant hydrothorax, and healthy controls (HCs) were examined by flow cytometry and ELISA. The potential association between the numbers of different subsets of Foxp3 + T cells and the values of clinical measures were analyzed.

RESULTS

The numbers of peripheral blood CD4(+)CD25(+)Foxp3(+) T cells were greater in malignant hydrothorax patients than in HCs, but fewer than those of hydrothorax in patients. The percentages of circulating IL-10(+) or LAP(+) CD4(+)CD25(+)Foxp3(+) T cells were higher than in the hydrothorax in patients with malignant hydrothorax. The numbers of circulating CD4(+)CD25(-)Foxp3(+) T cells were significantly fewer in patients with tuberculous hydrothorax than in HCs, and both the numbers of circulating CD4(+)CD25(+)Foxp3(+) and CD4(+)CD25(-)Foxp3(+) T cells were significantly fewer than in the hydrothorax in patients. Significantly higher percentages of circulating IL-10(+) or LAP(+) CD4(+)CD25(+)Foxp3(+) and CD4(+)CD25(-)Foxp3(+) T cells were detected in tuberculous hydrothorax patients. The numbers of CD4(+)CD25(+)Foxp3(+) and CD4(+)CD25(-)Foxp3(+) T cells were associated with hydrothorax adenosine deaminase (ADA) levels in tuberculous hydrothorax patients, while CD4(+)CD25(+)Foxp3(+) T cells were associated with carcino-embryonic antigen (CEA) in malignant hydrothorax patients. The concentrations of serum IL-6 and TGF-β in the patients were significantly higher than that in the HCs, but lower than that in the corresponding hydrothorax. A similar pattern of IL-10 was observed in different groups, except that there was no significant difference in the levels of serum IL-10 between the tuberculous hydrothorax patients and HCs.

CONCLUSIONS

CD4(+)CD25(-)Foxp3(+) T cells, which have lower inhibitory function than CD4(+)CD25(+)Foxp3(+) T cells, may play a role in tuberculous hydrothorax.

Paracrine co-delivery of TGF-β and IL-2 using CD4-targeted nanoparticles for induction and maintenance of regulatory T cells

The cytokine milieu is critical for orchestration of lineage development towards effector T cell (Teff) or regulatory T cell (Treg) subsets implicated in the progression of cancer and autoimmune disease. Importantly, the fitness and survival of the Treg subset is dependent on the cytokines Interleukin-2 (IL-2) and transforming growth factor beta (TGF-β). The production of these cytokines is impaired in autoimmunity increasing the probability of Treg conversion to aggressive effector cells in a proinflammatory microenvironment. Therapy using soluble TGF-β and IL-2 administration is hindered by the cytokines' toxic pleiotropic effects and hence bioavailability to CD4(+) T cell targets. Thus, there is a clear need for a strategy that rectifies the cytokine milieu in autoimmunity and inflammation leading to enhanced Treg stability, frequency and number. Here we show that inert biodegradable nanoparticles (NP) loaded with TGF-β and IL-2 and targeted to CD4(+) cells can induce CD4(+) Tregs in-vitro and expand their number in-vivo. The stability of induced Tregs with cytokine-loaded NP was enhanced leading to retention of their suppressive phenotype even in the presence of proinflammatory cytokines. Our results highlight the importance of a nanocarrier-based approach for stabilizing and expanding Tregs essential for cell-immunotherapy of inflammation and autoimmune disease.

All-trans retinoic acid favors the development and function of regulatory T cells from liver transplant patients

Graft-versus-host disease (GVHD) is an intractable complication in transplant patients. Regulatory T cells (Tregs) have the ability to prevent GVHD and consist of two subsets: natural Tregs (nTregs) and induced Tregs (iTregs). In comparison to nTregs, iTregs originate in the periphery under certain conditions and show improved proliferative and suppressive abilities in an inflammatory milieu. All-trans retinoic acid (atRA) favors Treg expansion and FoxP3 expression in human Tregs. However, whether atRA can affect the function of iTregs from transplant patients remains inconclusive. Therefore, we sorted naïve T cells from liver transplant patients and cultured them in vitro. Further analyses were performed to assess the suppressive function of iTregs in vitro and in vivo. atRA favored expansion and forkhead box P3 expression in iTregs from transplant patients. In comparison to iTregs from healthy donors, iTregs from transplant patients showed decent suppressive abilities in vitro and in vivo. Our findings suggest that atRA can potentially improve the development and function of iTregs from transplant patients. Furthermore, our results provide novel insights into Treg therapy in GVHD clinical trials.

Tolerance of activated pathogenic CD4+ T cells by transcriptional targeting of dendritic cells

We have recently shown that targeted expression of myelin oligodendrocyte glycoprotein (MOG) to dendritic cells with self-inactivating-lentivirus vectors induces antigen-specific tolerance in naive antigen-specific CD4+ T cells and protects mice from experimental autoimmune encephalomyelitis (EAE). In the present study, we demonstrate that this approach also induces tolerance of activated antigen-specific CD4+ T cells and completely protects mice from passive EAE induction. Tolerance induction did not correlate with the depletion of the preactivated antigen-specific CD4+ T cells. However, upon isolation and in vitro re-stimulation at day 6 after adoptive transfer the MOG-specific CD4+ T cells from the non-tolerized mice produced large amounts of inflammatory cytokines, whereas those from tolerized mice did not. This unresponsiveness correlated with the upregulation of regulatory molecules associated with anergy and regulatory T cells (Tregs). The in vivo depletion of Tregs resulted in EAE susceptibility of the tolerized animals, suggesting that these cells have indeed a role in tolerance induction/maintenance.

Progranulin facilitates conversion and function of regulatory T cells under inflammatory conditions

The progranulin (PGRN) is known to protect regulatory T cells (Tregs) from a negative regulation by TNF-α, and its levels are elevated in various kinds of autoimmune diseases. Whether PGRN directly regulates the conversion of CD4+CD25-T cells into Foxp3-expressing regulatory T cells (iTreg), and whether PGRN affects the immunosuppressive function of Tregs, however, remain unknown. In this study we provide evidences demonstrating that PGRN is able to stimulate the conversion of CD4+CD25-T cells into iTreg in a dose-dependent manner in vitro. In addition, PGRN showed synergistic effects with TGF-β1 on the induction of iTreg. PGRN was required for the immunosuppressive function of Tregs, since PGRN-deficient Tregs have a significant decreased ability to suppress the proliferation of effector T cells (Teff). In addition, PGRN deficiency caused a marked reduction in Tregs number in the course of inflammatory arthritis, although no significant difference was observed in the numbers of Tregs between wild type and PGRN deficient mice during development. Furthermore, PGRN deficiency led to significant upregulation of the Wnt receptor gene Fzd2. Collectively, this study reveals that PGRN directly regulates the numbers and function of Tregs under inflammatory conditions, and provides new insight into the immune regulatory mechanism of PGRN in the pathogenesis of inflammatory and immune-related diseases.

Low-dose 5-aza-2'-deoxycytidine pretreatment inhibits experimental autoimmune encephalomyelitis by induction of regulatory T cells

Forkhead box P3 (Foxp3) is the major transcription factor controlling the development and function of regulatory T (Treg) cells. Previous studies have indicated epigenetic regulation of Foxp3 expression. Here, we investigated whether the deoxyribonucleic acid (DNA) methyltransferase inhibitor 5-aza-2'-deoxycytidine (5-Aza) applied peripherally could modulate central nervous system (CNS) inflammation, by using a mouse experimental autoimmune encephalomyelitis (EAE) model. We found that disease activity was inhibited in a myelin oligodendrocyte glycoprotein (MOG) peptide-induced EAE mouse briefly pretreated with low-dose (0.15 mg/kg) 5-Aza, ameliorating significant CNS inflammatory responses, as indicated by greatly decreased proinflammatory cytokines. On the contrary, control EAE mice expressed high levels of IFN-γ and interleukin (IL)-17. In addition, 5-Aza treatment in vitro increased GFP expression in CD4(+)GFP(-) T cells isolated from GFP knock-in Foxp3 transgenic mice. Importantly, 5-Aza treatment increased Treg cell numbers, in EAE mice, at both disease onset and peak. However, Treg inhibition assays showed 5-Aza treatment did not enhance per-cell Treg inhibitory function, but did maintain a lower activation threshold for effector cells in EAE mice. In conclusion, 5-Aza treatment prevented EAE development and suppressed CNS inflammation, by increasing the number of Treg cells and inhibiting effector cells in the periphery.

Autoimmunity in 2012

The initiation and perpetuation of autoimmunity recognize numerous checkpoints, from the genomic susceptibility to the breakdown of tolerance. This latter phenomenon includes the loss of B cell anergy and T regulatory cell failure, as well as the production of autoantibodies and autoreactive T cells. These mechanisms ultimately lead to tissue injury via different mechanisms that span from the production of proinflammatory cytokines to the chemotaxis of immune cells to the target sites. The pathways to autoimmunity have been widely investigated over the past year and resulted in a number of articles in peer-reviewed journals that has increased by nearly 10 % compared to 2011. We herein follow on the attempt to provide a brief discussion of the majority of articles on autoimmune diseases that were published in the major immunology journals in the previous solar year. The selection is necessarily arbitrary and may thus not be seen as comprehensive but reflects current research trends. Indeed, 2012 articles were mostly dedicated to define new and old mechanisms with potential therapeutic implications in autoimmunity in general, though based on specific clinical conditions or animal models. As paradigmatic examples, the environmental influence on autoimmunity, Th17 changes modulating the autoimmune response, serum autoantibodies and B cell changes as biomarkers and therapeutic targets were major issues addressed by experimental articles in 2012. Further, a growing number of studies investigated the sex bias of autoimmunity and supported different working hypotheses to explain the female predominance, including sex chromosome changes and reproductive life factors. In conclusion, the resulting scenario illustrates that common factors may underlie different autoimmune diseases and this is well represented by the observed alterations in interferon-α and TGFβ or by the shared signaling pathways.

Transforming growth factor-β1-induced Treg cells inhibit the absorption of tissue-engineered cartilage caused by endogenous IFN-γ and TNF-α

BACKGROUND

In a previous study, we showed that IFN-γ and TNF-α induce bone marrow mesenchymal stem cell (BMMSC) apoptosis and absorption of tissue-engineered cartilage, but the induced regulatory T cells (iTreg) inhibit the function of IFN-γ and TNF-α. In this study, we investigated the effect of iTreg cells on the absorption of tissue-engineered cartilage caused by endogenous IFN-γ and TNF-α.

METHODS

We transfected the TGF-β1 gene into BMMSCs co-cultured with CD4(+) T lymphocytes. Then, we assessed the expression of iTreg cell markers (Foxp3, CD25 and CD 39) and IFN-γ and TNF-α and the level of apoptosis of BMMSCs. In addition, we characterized chondrogenic-committed cells from TGF-β1(+)BMMSCs and explored the role of iTreg cells.

RESULTS

IFN-γ and TNF-α were detected in the groups with CD4(+) T cells. In the group in which TGF-β1(+)BMMSCs were co-cultured with CD4(+) T cells, we observed Foxp3(+)Treg/ CD25(+)CD39(+) (17.58 ± 0.45%) cells as well as significant inhibition of BMMSC apoptosis and tissue-engineered cartilage absorption.

CONCLUSIONS

CD4(+) T cells led to the absorption of tissue-engineered cartilage through the secretion of endogenous IFN-γ and TNF-α, whose inflammatory functions were concomitantly suppressed by iTreg cells converted from CD4(+) T cells. This study is clinically relevant and adds to our understanding of the mechanism of tissue-engineered cartilage absorption.

Class I and II histone deacetylase inhibition by ITF2357 reduces SLE pathogenesis in vivo

We sought to determine if a specific class I and II HDAC inhibitor (ITF2357) was able to decrease disease in lupus-prone NZB/W mice through regulation of T cell profiles. From 22 to 38 weeks-of-age, NZB/W and non-lupus NZW mice were treated with ITF2357 (5 mg/kg or 10 mg/kg), or vehicle control. Body weight and proteinuria were measured every 2 weeks, while sera anti-dsDNA and cytokine levels were measured every 4 weeks. Kidney disease was determined by sera IgG levels, immune complex deposition, and renal pathology. T lymphocyte profiles were assessed using flow cytometric analyses. Our results showed that NZB/W mice treated with the 10 mg/kgof ITF2357 had decreased renal disease and inflammatory cytokines in the sera. Treatment with ITF2357 decreased the Th17 phenotype while increasing the percentage of Tregs as well as Foxp3 acetylation. These results suggest that specific HDAC inhibition may decrease disease by altering T cell differentiation and acetylation.

Surge in regulatory T cells does not prevent onset of hyperglycemia in NOD mice: immune profiles do not correlate with disease severity

Immune profiling of non-obese diabetic (NOD) is a widely employed tool to assess the mechanisms of inflammatory insulitis. Our analysis of the female NOD colony revealed similar distribution of lymphoid lineages to wild type mice, and at various ages of prediabetic and diabetic mice. The profiles of mesenteric and pancreatic lymph nodes differ and often change reciprocally due to directed migration of T cells towards the site of inflammation. Significant events in our colony include early decline in CD4(+)CD25(+)CD62L(+) Treg, accompanied by gradual increase in CD4(+)CD25(+)FoxP3(+) Treg in peripheral lymphoid organs and pancreatic infiltrates. Impressively, aged euglycemic mice display significant transient rise in CD4(+)CD25(-)FoxP3(+) Treg in the thymus, pancreas and draining lymph nodes. A significant difference was superior viability of effector and suppressor cells from new onset diabetics in the presence of high interleukin-2 (IL-2) concentrations in vitro as compared to cells of prediabetic mice. Overall, we found no correlation between FoxP3(+) Treg in the pancreatic lymph nodes and the inflammatory scores of individual NOD mice. CD25(-)FoxP3(+) Treg are markedly increased in the pancreatic infiltrates in late stages of inflammation, possibly an effort to counteract destructive insulitis. Considering extensive evidence that Treg in aged NOD mice are functionally sufficient, quantitative profiling evolves as an unreliable tool to assess mechanism and causes of inflammation under baseline conditions. Immune profiles are modulated by thymic output, cell migration, shedding of markers, proliferation, survival and in-situ evolution of regulatory cells.

Regulatory T cells and B cells: implication on autoimmune diseases

The regulatory T (Treg) cells play an important role in the maintenance of homeostasis and the prevention of autoimmune diseases. Although most studies are focusing on the role of Treg cells in T cells and T cells-mediated diseases, these cells also directly affect B cells and other non-T cells. This manuscript updates the role of Treg cells on the B cells and B cell-mediated diseases. In addition, the mechanisms whereby Treg cells suppress B cell responses have been discussed.

Differential role of all-trans retinoic acid in promoting the development of CD4+ and CD8+ regulatory T cells

It is known that ATRA promotes the development of TGF-β-induced CD4(+)Foxp3(+) iTregs, which play a vital role in the prevention of autoimmune diseases; however, the role of ATRA in facilitating the differentiation and function of CD8(+)Foxp3(+) iTregs remains elusive. Using a head-to-head comparison, we found that ATRA promoted expression of Foxp3 and development of CD4(+) iTregs, but it did not promote Foxp3 expression on CD8(+) cells. Using a standard in vitro assay, we demonstrated that CD8(+) iTregs induced by TGF-β and ATRA were not superior to CD8(+) iTregs induced by TGF-β alone. In cGVHD, in a typical lupus syndrome model where DBA2 spleen cells were transferred to DBA2xC57BL/6 F1 mice, we observed that both CD8(+) iTregs induced by TGF-β and ATRA and those induced by TGF-β alone had similar therapeutic effects. ATRA did not boost but, conversely, impaired the differentiation and function of human CD8(+) iTregs. CD8(+) cells expressed the ATRA receptor RAR and responded to ATRA, similar to CD4(+) cells. We have identified the differential role of ATRA in promoting Foxp3(+) Tregs in CD4(+) and CD8(+) cell populations. These results will help to determine a protocol for developing different Treg cell populations and may provide novel insights into clinical cell therapy for patients with autoimmune diseases and those needing organ transplantation.

Medullary thymic epithelial cell depletion leads to autoimmune hepatitis

TRAF6, an E3 ubiquitin protein ligase, plays a critical role in T cell tolerance by regulating medullary thymic epithelial cell (mTEC) development. mTECs regulate T cell tolerance by ectopically expressing self-antigens and eliminating autoreactive T cells in the thymus. Here we show that mice with mTEC depletion due to conditional deletion of Traf6 expression in murine thymic epithelial cells (Traf6ΔTEC mice) showed a surprisingly narrow spectrum of autoimmunity affecting the liver. The liver inflammation in Traf6ΔTEC mice exhibited all the histological and immunological characteristics of human autoimmune hepatitis (AIH). The role of T cells in AIH establishment was supported by intrahepatic T cell population changes and AIH development after transfer of liver T cells into immunodeficient mice. Despite a 50% reduction in natural Treg thymic output, peripheral tolerance in Traf6ΔTEC mice was normal, whereas compensatory T regulatory mechanisms were evident in the liver of these animals. These data indicate that mTECs exert a cell-autonomous role in central T cell tolerance and organ-specific autoimmunity, but play a redundant role in peripheral tolerance. These findings also demonstrate that Traf6ΔTEC mice are a relevant model with which to study the pathophysiology of AIH, as well as autoantigen-specific T cell responses and regulatory mechanisms underlying this disease.

Overexpression of Epstein-Barr virus-induced gene 3 protein (EBI3) in MRL/lpr mice suppresses their lupus nephritis by activating regulatory T cells

To identify the effect of an imbalance of Th1/Th2 cytokines on the development of autoimmune glomerulonephritis (lupus nephritis), we studied the modification of pathological changes in diffuse proliferative glomerulonephritis (DPGN) and membranous glomerulonephritis (MGN) in MRL/lpr mice, which are animal models of systemic lupus erythematosus (SLE). Transgenic MRL/lpr mice (Tg) that overexpressed Epstein--Barr virus-induced gene 3 (EBI3) showed almost normal renal function, which was demonstrated by healing of glomerulonephritis upon renal histology, as compared to the wild-type MRL/lpr (Wt) mice. The levels of anti-dsDNA antibodies and IgE decreased in the Tg mice compared to Wt mice. Quantitative real-time PCR indicated an increase in the mRNA levels of FoxP3, and a decrease in that of IFNγ in the splenocytes of Tg mice as compared to Wt mice. In addition, flow cytometric analysis showed an increase in CD4(+)CD25(+)FoxP3(+)-T cells in the former, as compared to the latter. Our findings suggest that EBI3-overexpression in MRL/lpr mice induces generation of regulatory T cells, which causes suppression of autoimmune and inflammatory reactions by affecting the Th1/Th2 cytokine balance.

Tolerance induction by hair-specific keratins in murine alopecia areata

AA is a presumptive autoimmune disease, severely damaging the hair follicle. Hair- and nail-specific keratins are discussed as potential candidates, which we controlled in C3H/HeJ mice that develop AA spontaneously or after skin transplantation. From nine keratins, K71 and K31 peptides supported T cell activation when presented by DCs to syngeneic naive T cells, and young C3H/HeJ mice receiving s.c. injections of peptide-loaded DC developed AA. The frequency of K71- and K31-specific CD4(+) and CD8(+) T cells increased four- to fivefold by vaccination, which corresponds with the frequency seen in skin transplantation-induced AA mice. Also, accessory molecule expression, the cytokine profile with a dominance of IFN-γ-expressing T cells, the proliferative response against AA lysate or peptide-loaded DCs, as well as peptide-specific cytotoxic T cells were similar in keratin peptide- and skin transplantation-induced AA. Instead, vaccination with soluble K71 or K31 peptides significantly retarded AA induction and prevented progression. Soluble peptide vaccination did not provoke immunosuppression but induced long-lasting T cell anergy with unresponsiveness to DC-presented K71 and K31 peptides. Thus, keratins K71 and K31 contribute to AA induction, and peptide application in a nonimmunogenic form serves as an efficient therapeutic.

Regulatory T cells vs Th17: differentiation of Th17 versus Treg, are the mutually exclusive?

Naive CD4(+) cells differentiate into T helper (Th1, Th2, Th9, Th17) and regulatory T (Treg) cells to execute their immunologic function. Whereas TGF-β suppresses Th1 and Th2 cell differentiation, this cytokine promotes Th9, Th17 and Foxp3(+) regulatory T cells depending upon the presence of other cytokines. IL-6 promotes Th17, but suppresses regulatory T cell differentiation. Moreover, natural but not TGF-β-induced regulatory T cells convert into Th17 cells in the inflammatory milieu. Here an update of T cell differentiation and conversion, as well as underlying mechanisms are given.

Serum IFN-λ1 is abnormally elevated in rheumatoid arthritis patients

Interferon (IFN)-λ1 is a newly described cytokine that is known for its proinflammatory activity in viral infection and in cancer. Because recent studies indicated that IFN-λ can influence significantly the innate and adaptive immune response, we studied IFN-λ in a prototypic systemic autoimmune disease, rheumatoid arthritis (RA). It was found that RA patients had higher mRNA levels in PBMC and higher serum levels of IFN-λ1 in comparison with healthy matched controls and ankylosing spondylitis (AS) patients. Although there was no correlation between serum IFN-λ1 and RA autoantibodies, RA patients that presented knee joint involvement displayed higher serum IFN-λ1 than patients without knee joint involvement, suggesting that abnormally elevated IFN-λ1 levels in RA can associate with knee joint disease.

Advances in distinguishing natural from induced Foxp3(+) regulatory T cells

For more than a decade now, the regulatory T (Treg) cell has widely been considered as a critical subpopulation of T cells which can suppress effector T cell responses as well as suppressing the activity of other immune cells, such as mast cell, dendritic cells, and B cells. Treg cells have been broadly characterized as comprising of two main populations: thymus-derived natural Treg (nTreg) cells, and peripherally generated induced Treg (iTreg) cells. Both subsets have similar phenotypic characteristics and comparable suppressive function against T cell-mediated immune response and diseases. However, both Foxp3 positive Treg subsets exhibit some specific differences such as different mRNA transcripts and protein expression, epigenetic modification, and stability. These subtle differences reinforce the notion that they represent unique and distinct subsets. Accurately distinguishing iTregs from nTregs will help to clarify the biological features and contributions of each Treg subsets in peripheral tolerance, autoimmunity and tumor immunity. One difficult problem is that it has not been possible to distinguish iTregs from nTregs using surface markers until two recent articles were published to address this possibility. This review will focus on very recent advances in using molecular markers to differentiate these Treg subsets.

Autoimmunity in 2011

The mechanisms leading to the onset and perpetuation of systemic and tissue-specific autoimmune diseases are complex, and numerous hypotheses have been proposed or confirmed over the past 12 months. It is particularly of note that the number of articles published during 2011 in the major immunology and autoimmunity journals increased by 3 % compared to the previous year. The present article is dedicated to a brief review of the reported data and, albeit not comprehensive of all articles, is aimed at identifying common and future themes. First, clinical researchers were particularly dedicated to defining refractory forms of diseases and to discuss the use and switch of therapeutic monoclonal antibodies in everyday practice. Second, following the plethora of genome-wide association studies reported in most multifactorial diseases, it became clear that genomics cannot fully explain the individual susceptibility and additional environmental or epigenetic factors are necessary. Both these components were widely investigated, both in organ-specific (i.e., type 1 diabetes) and systemic (i.e., systemic lupus erythematosus) diseases. Third, a large number of 2011 works published in the autoimmunity area are dedicated to dissect pathogenetic mechanisms of tolerance breakdown in general or in specific conditions. While our understanding of T regulatory and Th17 cells has significantly increased in 2011, it is of note that most of the proposed lines of evidence identify potential targets for future treatments and should not be overlooked.

Induced Foxp3(+) regulatory T cells: a potential new weapon to treat autoimmune and inflammatory diseases?

Foxp3(+) T regulatory cells (Tregs) consisting of natural and induced Treg subsets play a crucial role in the maintenance of immune homeostasis against self-antigen. The actions designed to correct defects in numbers or functions of Tregs may be therapeutic in the treatment of autoimmune diseases. While recent studies demonstrated that natural Tregs are instable and dysfunctional in the inflammatory condition, induced Tregs (iTregs) may have a different feature. Here we review the progress of iTregs, particularly focus on their stability and function in the established autoimmune diseases. The advantage of iTregs as therapeutics used under inflammatory conditions is highlighted. Proper generation and manipulation of iTregs used for cellular therapy may provide a promise for the treatment of many autoimmune and inflammatory diseases.