Proinflammatory mediator-induced reversal of CD4+,CD25+ regulatory T cell-mediated suppression in rheumatoid arthritis

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

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

Autophagy pathways in autoimmune diseases

Autophagy comprises a growing range of cellular pathways, which occupy central roles in response to energy deprivation, organelle turnover and proteostasis. Over the years, autophagy has been increasingly linked to governing several aspects of immunity, including host defence against various pathogens, unconventional secretion of cytokines and antigen presentation. While canonical autophagy-mediated antigen processing in thymic epithelial cells supports the generation of a self-tolerant CD4+ T cell repertoire, mounting evidence suggests that deregulated autophagy pathways contribute to or sustain autoimmune responses. In animal models of multiple sclerosis (MS), non-canonical autophagy pathways such as microtubule-associated protein 1 A/1 B-light chain 3 (LC3)-associated phagocytosis can contribute to major histocompatibility complex (MHC) class II presentation of autoantigen, thereby amplifying autoreactive CD4+ T cell responses. In systemic lupus erythematosus (SLE), increased type 1 interferon production is linked to excessive autophagy in plasmacytoid dendritic cells (DCs). In rheumatoid arthritis (RA), autophagy proteins contribute to pathological citrullination of autoantigen. Immunotherapies effective in autoimmune diseases modulate autophagy functions, and strategies harnessing autophagy pathways to restrain autoimmune responses have been developed. This review illustrates recent insights in how autophagy, distinct autophagy pathways and autophagy protein functions intersect with the evolution and progression of autoimmune diseases, focusing on MS, SLE and RA.

ASSOCIATION OF SOME IMMUNOLOGICAL BIOMARKERS WITH RHEUMATOID ARTHRITIS PATIENTS IN THI-QAR PROVINCE

OBJECTIVE

The aim: The aim of this research is to evaluate some immunological biomarkers in cases of Rheumatoid arthritis and to verify their correlation with activity of disease among the population of Thi-Qar province.

PATIENTS AND METHODS

Matherials and methods: This study included 45 cases of rheumatoid arthritis and 45 healthy subjects. All cases underwent complete history taking, thor¬ough clinical examination, and laboratory tests including erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), Anti-citrulline antibody (Anti-CCP) and rheumatoid factor (RF). IL-17and TNF-α blood level was measured by Enzyme Linked Immunosorbent Assay (ELISA) method. DAS-28 (Disease activity score 28) was evaluated.

RESULTS

Results: Serum levels TNF-α was higher in Rheumatoid arthritis patients (424.3±19.46 pg/ml) than in healthy individuals (112.7±4.73 pg/ml), and IL-17 blood levels were higher in Rheumatoid arthritis patients (233.5±241.4 pg/ml) than the healthy individuals group (47.24±49.7 pg/ml). There was significant association found among IL-17, DAS-28, CRP and hemoglobin levels.

CONCLUSION

Conclusions: In conclusion, IL-17 blood levels were significantly increased in peoples with rheumatoid arthritis than in healthy individuals. Its significant relationship with DAS-28 suggested that the level of IL-17 in serum could be important immunological biomarker for activity of disease in disease of Rheumatoid arthritis.

Regulatory T cells (Tregs) and their therapeutic potential against autoimmune disorders - Advances and challenges

Autoimmune diseases are caused when immune cells act against self-protein. This biological self-non-self-discrimination phenomenon is controlled by a distinct group of lymphocytes known as regulatory T cells (Tregs), which are key inflammatory response regulators and play a pivotal role in immune tolerance and homeostasis. Treg-mediated robust immunosuppression provides self-tolerance and protection against autoimmune diseases. However, once this system fails to operate or poorly operate, it leads to an extreme situation where immune system reacts against self-antigens and destroys host organs, thus causing autoimmune diseases. Tregs can target both innate and adaptive immunity via modulating multiple immune cells such as neutrophils, monocytes, antigen-presenting cells, B cells, and T cells. This review highlights the Treg-mediated immunosuppression, role of several markers and their interplay during Treg development and differentiation, and advances in therapeutic aspects of Treg cells to reduce severity of autoimmunity-related conditions along with emphasizing limitations and challenges of their usages.

OX40-Fc Fusion Protein Alleviates PD-1-Fc-Aggravated Rheumatoid Arthritis by Inhibiting Inflammatory Response

BACKGROUND

Researches have confirmed that the abnormal signals of OX40 and PD-1 lead to the changes of T cell biological behavior, thus participating the immunopathological process of RA. However, the pathogenesis of RA immunopathological process has not been clarified yet.

METHODS

30 DBA/1 mice were randomly divided into 5 groups (6 mice per group): control group, collagen-induced arthritis (CIA) group, PD-1-Fc/CIA group, OX40-Fc/CIA group, and PD-1-Fc + OX40-Fc/CIA group. The pathological changes in mice joints were observed by H&E staining. The proportion of CD4+ T, CD8+ T, CD28+, and CD19+ cells in peripheral blood mononuclear cells (PBMCs) was detected by flow cytometry. Serum inflammatory factors (CRP, IL-2, IL-4, IL-1β, INF-γ) and bone metabolism-related genes (CTX-I, TRACP-5b, BALP) were detected by ELISA assay. Western blotting was applied to measure the NF-κB signaling pathway-related protein (p-IKKβ, p-IκBα, p50) expression in synovial tissue of mice joint.

RESULTS

Compared with the control group, CIA mice showed significant increases in arthritis score and pathological score. In the CIA group, a marked decrease was identified in the proportion of CD8+ T, CD19+, and CD68+ cells. Additionally, the CIA group was associated with upregulation of secretion of inflammatory factors in serum and expression of bone metabolism-related genes and NF-κB pathway-related proteins. Compared with the CIA group, the same indexes above showed a further aggravation in the PD-1-Fc group while all indexes improved in the OX40-Fc group. Besides, OX40-Fc fusion protein slowed down significantly the further deterioration of CIA mouse pathological process caused by PD-1-Fc fusion protein.

CONCLUSION

OX40-Fc fusion protein alleviates PD-1-Fc-aggravated RA by inhibiting inflammatory response. This research provides biological markers with clinical significance for diagnosis and prognosis of RA, as well as offers theoretical and experimental foundation to the new targets for immune intervention.

Immunomodulatory matrix-bound nanovesicles mitigate acute and chronic pristane-induced rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation and destruction of synovial joints affecting ~7.5 million people worldwide. Disease pathology is driven by an imbalance in the ratio of pro-inflammatory vs. anti-inflammatory immune cells, especially macrophages. Modulation of macrophage phenotype, specifically an M1 to M2, pro- to anti-inflammatory transition, can be induced by biologic scaffold materials composed of extracellular matrix (ECM). The ECM-based immunomodulatory effect is thought to be mediated in part through recently identified matrix-bound nanovesicles (MBV) embedded within ECM. Isolated MBV was delivered via intravenous (i.v.) or peri-articular (p.a.) injection to rats with pristane-induced arthritis (PIA). The results of MBV administration were compared to intraperitoneal (i.p.) administration of methotrexate (MTX), the clinical standard of care. Relative to the diseased animals, i.p. MTX, i.v. MBV, and p.a. MBV reduced arthritis scores in both acute and chronic pristane-induced arthritis, decreased synovial inflammation, decreased adverse joint remodeling, and reduced the ratio of synovial and splenic M1 to M2 macrophages (p < 0.05). Both p.a. and i.v. MBV reduced the serum concentration of RA and PIA biomarkers CXCL10 and MCP-3 in the acute and chronic phases of disease (p < 0.05). Flow-cytometry revealed the presence of a systemic CD43hi/His48lo/CD206+, immunoregulatory monocyte population unique to p.a. and i.v. MBV treatment associated with disease resolution. The results show that the therapeutic efficacy of MBV is equal to that of MTX for the management of acute and chronic pristane-induced arthritis and, further, this effect is associated with modulation of local synovial macrophages and systemic myeloid populations.

Reduction of Oxidative Stress in Peripheral Blood Mononuclear Cells Attenuates the Inflammatory Response of Fibroblast-like Synoviocytes in Rheumatoid Arthritis

The production and oxidation mechanism of reactive oxygen species (ROS) are out of balance in rheumatoid arthritis (RA). However, the correlation between ROS and T cell subsets in RA remains unclear. Peripheral blood mononuclear cells (PBMCs) from patients with RA (n = 40) and healthy controls (n = 10) were isolated from whole blood samples. Synovial tissues (n = 3) and synovial fluid (n = 10) were obtained from patients with RA. The repartition of T cell subsets and expression of ROS and cytokines were examined according to RA severity. Fibroblast-like synoviocytes (FLSs) from patients with RA were stimulated with PBMCs and the expression of inflammation-related molecules were measured by RT-PCR and cytokine array. Regulatory T cells from patients with moderate (5.1 > DAS28 ≥ 3.2) RA showed the highest expression of mitochondrial ROS among the groups based on disease severity. Although ROS levels steadily increased with RA severity, there was a slight decline in severe RA (DAS28 ≥ 5.1) compared with moderate RA. The expression of inflammatory cytokines in RA FLSs were significantly inhibited when FLSs were co-cultured with PBMCs treated with ROS inhibitor. These findings provide a novel approach to suppress inflammatory response of FLSs through ROS regulation in PBMCs.

Immune Phenotyping of Patients With Acute Vogt-Koyanagi-Harada Syndrome Before and After Glucocorticoids Therapy

Previous studies have established that disturbed lymphocytes are involved in the pathogenesis of Vogt-Koyanagi-Harada (VKH) syndrome. Accordingly, glucocorticoids (GCs), with their well-recognized immune-suppressive function, have been widely used for treatment of VKH patients with acute relapses. However, the systemic response of diverse immune cells to GC therapy in VKH is poorly characterized. To address this issue, we analyzed immune cell subpopulations and their phenotype, as well as cytokine profiles in peripheral blood from VKH patients (n=25) and health controls (HCs, n=21) by flow cytometry and luminex technique, respectively. For 16 patients underwent GC therapy (methylprednisolone, MP), the aforementioned measurements as well as the transcriptome data from patients before and after one-week’s GC therapy were also compared to interrogate the systemic immune response to GC therapy. Lymphocyte composition in the blood was different in VKH patients and HCs. VKH patients had significantly higher numbers of T cells with more activated, polarized and differentiated phenotype, more unswitched memory B cells and monocytes, as compared to HCs. MP treatment resulted in decreased frequencies of T cells and NK cells, inhibited NK cell activation and T cell differentiation, and more profoundly, a marked shift in the distribution of monocyte subsets. Collectively, our findings suggest that advanced activation and differentiation, as well as dysregulated numbers of peripheral lymphocytes are the major immunological features of VKH, and GC therapy with MP not only inhibits T cell activation directly, but also affects monocyte subsets, which might combinatorically result in the inhibition of the pathogenic immune response.

Why remission is not enough: underlying disease mechanisms in RA that prevent cure

Cure is the aspirational aim for the treatment of all diseases, including chronic inflammatory conditions such as rheumatoid arthritis (RA); however, it has only been during the twenty-first century that remission, let alone cure, has been a regularly achievable target in RA. Little research has been carried out on how to cure RA, and the term 'cure' still requires definition for this disease. Even now, achieving a cure seems to be a rare occurrence among individuals with RA. Therefore, this Review is aimed at addressing the obstacles to the achievement of cure in RA. The differences between remission and cure in RA are first defined, followed by a discussion of the underlying factors (referred to as drivers) that prevent the achievement of cure in RA by triggering sustained immune activation and effector cytokine production. Such drivers include adaptive immune system activation, mesenchymal tissue priming and so-called 'remote' (non-immune and non-articular) factors. Strategies to target these drivers are also presented, with an emphasis on the development of strategies that could complement currently used cytokine inhibition and thereby improve the likelihood of curing RA.

Regulatory T cell heterogeneity and therapy in autoimmune diseases

Regulatory T (Treg) cells are a group of CD4⁺ T cell with high expression of CD25 and cell linage specific transcription factor forkhead box P3 (Foxp3) and play a vital role in maintaining immune homeostasis. In the last two decades, researchers have shown that Treg cells involved in the occurrence, development and prognosis of many diseases, especially in autoimmune diseases. Treg targeted therapies, such as low-dose interleukin-2 (IL-2) treatment and Treg infusion therapy, which are aimed at restoring the number or function of Treg cells, have become a hot topic in clinical trials of these diseases. It is believed that Treg cells are heterogeneous. Different subsets of Treg cells have various functions and play different parts in immunomodulatory. Gaining insights into Treg heterogeneity will help us further understand the function of Treg cells and provide news ideas for the selective therapeutic manipulation of Treg cells. In this review, we mainly summarize the heterogeneity of Treg cells and their potential therapeutic value in autoimmune diseases.

TRI microparticles prevent inflammatory arthritis in a collagen-induced arthritis model

Despite recent progress in the treatment of rheumatoid arthritis (RA), many patients still fail to achieve remission or low disease activity. An imbalance between auto-reactive effector T cells (Teff) and regulatory T cells (Treg) may contribute to joint inflammation and damage in RA. Therefore, restoring this balance is a promising approach for the treatment of inflammatory arthritis. Accordingly, our group has previously shown that the combination of TGF-β-releasing microparticles (MP), rapamycin-releasing MP, and IL-2-releasing MP (TRI MP) can effectively increase the ratio of Tregs to Teff in vivo and provide disease protection in several preclinical models. In this study TRI MP was evaluated in the collagen-induced arthritis (CIA) model. Although this formulation has been tested previously in models of destructive inflammation and transplantation, this is the first model of autoimmunity for which this therapy has been applied. In this context, TRI MP effectively reduced arthritis incidence, the severity of arthritis scores, and bone erosion. The proposed mechanism of action includes not only reducing CD4+ T cell proliferation, but also expanding a regulatory population in the periphery soon after TRI MP administration. These changes were reflected in the CD4+ T cell population that infiltrated the paws at the onset of arthritis and were associated with a reduction of immune infiltrate and inflammatory myeloid cells in the paws. TRI MP administration also reduced the titer of collagen antibodies, however the contribution of this reduced titer to disease protection remains uncertain since there was no correlation between collagen antibody titer and arthritis score.

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-7 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.

Nonendocrine mechanisms of sex bias in rheumatic diseases

Rheumatic diseases affect a wide range of individuals of all ages, but the most common diseases occur more frequently in women than in men, at ratios of up to ten women to one man. Despite a growing number of studies on sex bias in rheumatic diseases, sex-specific health care is limited and sex specificity is not systematically integrated into treatment regimens. Women and men differ in three major biological points: the number of X chromosomes per cell, the type and quantities of sex hormones present and the ability to be pregnant, all of which have immunological consequences. Could a greater understanding of these differences lead to a new era of personalized sex-specific medicine? This Review focuses on the main genetic and epigenetic mechanisms that have been put forward to explain sex bias in rheumatic diseases, including X chromosome inactivation, sex chromosome aneuploidy and microchimerism. The influence of sex hormones is not discussed in detail in this Review, as it has been well described elsewhere. Understanding the sex-specific factors that contribute to the initiation and progression of rheumatic diseases will enable progress to be made in the diagnosis, treatment and management of all patients with these conditions.

Immunophenotype of circulatory T-helper cells in patients with non-segmental vitiligo

Introduction

Non-segmental vitiligo (NSV) is an immune-mediated skin depigmentation disease. Cytokine-mediated interaction between T lymphocytes and melanocytes leads to death of melanocytes, causing a defect in melanin synthesis and thereby depigmentation. There is an increased population of T-helper cells in the skin lesions as well as in the peripheral circulation in NSV. However, the relative percentage of each T-cell phenotype in the disease pathogenesis is rarely studied.

Aim

To study the immunophenotype of the different T-helper/Treg cell subsets in patients with NSV, in comparison to healthy controls.

Material and methods

A total of 80 patients with NSV and eighty age- and gender-matched healthy controls were recruited in this cross-sectional study. Disease activity was determined by vitiligo index of disease activity (VIDA) scoring. Peripheral blood mononuclear cells were separated by Ficoll-Paque density centrifugation, and T-cell immunophenotyping was done by flow cytometric analysis.

Results

In patients with NSV, we observed an imbalance in T-cell immunophenotype, characterized by an increase in Th1 (p < 0.0001) and Th17 cells (p = 0.01). There is no difference in relative percentage of Th2/Treg cells, as compared to the healthy controls (p > 0.05).

Conclusions

There is a significant immune-dysregulation with a preponderance of circulatory Th1/Th17 phenotype in NSV patients.

IL-7 is a Key Driver Cytokine in Spondyloarthritis?

The rationale for a type 17 signature in the pathogenesis of spondyloarthritis (SpA) has been increasing and being ratified in studies recently. IL-7 is a cytokine whose ability to stimulate IL-17 production in both innate and adaptive immunity cells has made it a promising target not only for a better understanding of the disease as well as an important potential therapeutic target in patients with SpA.

T cells engrafted with a UniCAR 28/z outperform UniCAR BB/z-transduced T cells in the face of regulatory T cell-mediated immunosuppression

Adoptive transfer of chimeric antigen receptor (CAR)-equipped T cells have demonstrated astonishing clinical efficacy in hematological malignancies recently culminating in the approval of two CAR T cell products. Despite this tremendous success, CAR T cell approaches have still achieved only moderate efficacy against solid tumors. As a major obstacle, engineered conventional T cells (Tconvs) face an anti-inflammatory, hostile tumor microenvironment often infiltrated by highly suppressive regulatory T cells (Tregs). Thus, potent CAR T cell treatment of solid tumors requires efficient activation of Tconvs via their engrafted CAR to overcome Treg-mediated immunosuppression. In that regard, selecting an optimal intracellular signaling domain might represent a crucial step to achieve best clinical efficiency. To shed light on this issue and to investigate responsiveness to Treg inhibition, we engrafted Tconvs with switchable universal CARs (UniCARs) harboring intracellularly the CD3ζ domain alone or in combination with costimulatory CD28 or 4-1BB. Our studies reveal that UniCAR ζ-, and UniCAR BB/ζ-engineered Tconvs are strongly impaired by activated Tregs, whereas UniCARs providing CD28 costimulation overcome Treg-mediated suppression both in vitro and in vivo. Compared to UniCAR ζ- and UniCAR BB/ζ-modified cells, UniCAR 28/ζ-armed Tconvs secrete significantly higher amounts of Th1-related cytokines and, furthermore, levels of these cytokines are elevated even upon exposure to Tregs. Thus, in contrast to 4-1BB costimulation, CD28 signaling in UniCAR-transduced Tconvs seems to foster a pro-inflammatory milieu, which contributes to enhanced resistance to Treg suppression. Overall, our results may have significant implications for CAR T cell-based immunotherapies of solid tumors strongly invaded by Tregs.

Turning the Tide Against Regulatory T Cells

Regulatory T (Treg) cells play crucial roles in health and disease through their immunosuppressive properties against various immune cells. In this review we will focus on the inhibitory role of Treg cells in anti-tumor immunity. We outline how Treg cells restrict T cell function based on our understanding of T cell biology, and how we can shift the equilibrium against regulatory T cells. To date, numerous strategies have been proposed to limit the suppressive effects of Treg cells, including Treg cell neutralization, destabilizing Treg cells and rendering T cells resistant to Treg cells. Here, we focus on key mechanisms which render T cells resistant to the suppressive effects of Treg cells. Lastly, we also examine current limitations and caveats of overcoming the inhibitory activity of Treg cells, and briefly discuss the potential to target Treg cell resistance in the context of anti-tumor immunity.

ST2/MyD88 Deficiency Protects Mice against Acute Graft-versus-Host Disease and Spares Regulatory T Cells

Acute graft-versus-host disease (aGVHD) hinders the efficacy of allogeneic hematopoietic cell transplantation (HCT). Plasma levels of soluble membrane-bound ST2 (ST2) are elevated in human and murine aGVHD and correlated to type 1 T cells response. ST2 signals through the adapter protein MyD88. The role of MyD88 in T cells during aGVHD has yet to be elucidated. We found that knocking out MyD88 in the donor T cells protected against aGVHD independent of IL-1R and TLR4 signaling in two murine HCT models. This protection was entirely driven by MyD88^-/- CD4 T cells. Transplanting donor MyD88^-/- conventional T cells (Tcons) with wild-type (WT) or MyD88^-/- regulatory T cells (Tregs) lowered aGVHD severity and mortality. Transcriptome analysis of sorted MyD88^-/- CD4 T cells from the intestine 10 d post-HCT showed lower levels of Il1rl1 (gene of ST2), Ifng, Csf2, Stat5, Batf, and Jak2 Transplanting donor ST2^-/- Tcons with WT or ST2^-/- Tregs showed a similar phenotype with what we observed when using donor MyD88^-/- Tcons. Decreased ST2 was confirmed at the protein level with less secretion of soluble ST2 and more expression of ST2 compared with WT T cells. Our data suggest that Treg suppression from lack of MyD88 signaling in donor Tcons during alloreactivity uses the ST2 but not the IL-1R or TLR4 pathways, and ST2 represents a potential aGVHD therapeutic target sparing Tregs.

Humanized Mouse Models of Rheumatoid Arthritis for Studies on Immunopathogenesis and Preclinical Testing of Cell-Based Therapies

Rodent models of rheumatoid arthritis (RA) have been used over decades to study the immunopathogenesis of the disease and to explore intervention strategies. Nevertheless, mouse models of RA reach their limit when it comes to testing of new therapeutic approaches such as cell-based therapies. Differences between the human and the murine immune system make it difficult to draw reliable conclusions about the success of immunotherapies. To overcome this issue, humanized mouse models have been established that mimic components of the human immune system in mice. Two main strategies have been pursued for humanization: the introduction of human transgenes such as human leukocyte antigen molecules or specific T cell receptors, and the generation of mouse/human chimera by transferring human cells or tissues into immunodeficient mice. Recently, both approaches have been combined to achieve more sophisticated humanized models of autoimmune diseases. This review discusses limitations of conventional mouse models of RA-like disease and provides a closer look into studies in humanized mice exploring their usefulness and necessity as preclinical models for testing of cell-based therapies in autoimmune diseases such as RA.

Tumor Necrosis Factor and Regulatory T Cells

CD4⁺CD25⁺FoxP3⁺ regulatory T (Treg) cells play major roles in the maintenance of immune homeostasis. In this review, we comprehensively describe the relationship between tumor necrosis factor (TNF) and Treg cells, focusing on the effects of TNF on Treg cells and on TNF-producing Treg cells. Contradictory results have been reported for the effect of TNF on the suppressive activity of Treg cells. In patients with rheumatoid arthritis, TNF has been shown to reduce the suppressive activity of Treg cells. Meanwhile, however, TNF has also been reported to maintain the suppressive activity of Treg cells via a TNFR2-mediated mechanism. In addition, Treg cells have been found to acquire the ability to produce TNF under inflammatory conditions, such as acute viral hepatitis. These TNF-producing Treg cells exhibit T helper 17-like features and hold significance in various human diseases.

Immune tolerance therapies for autoimmune diseases based on heat shock protein T-cell epitopes

Experimental models of autoimmune diseases have revealed the disease protective role of heat shock proteins (HSPs). Both the administration of exogenous extracellular, mostly recombinant, HSP and the experimental co-induction of endogenous intracellular HSP in models have been shown to lead to production of disease protective regulatory T cells (Tregs). Similar to HSP taken up from extracellular bodily fluids, due to stress-related autophagy upregulated HSP also from intracellular sources is a major provider for the major histocompatibility class II (MHCII) ligandome; therefore, both extracellular and intracellular HSP can be prominent targets of Treg. The development of therapeutic peptide vaccines for the restoration of immune tolerance in inflammatory diseases is an area of intensive research. In this area, HSPs are a target for tolerance-inducing T-cell therapy, because of their wide expression in inflamed tissues. In humans, in whom the actual disease trigger is frequently unknown, HSP peptides offer chances for tolerance-promoting interventions through induction of HSP-specific Treg. Recently, we have shown the ability of a bacterial HSP70-derived peptide, HSP70-B29, to induce HSP-specific Tregs that suppressed arthritis by cross-recognition of their mammalian HSP70 homologues, abundantly present in the MHCII ligandome of stressed mouse and human antigen-presenting cells in inflamed tissues.This article is part of the theme issue 'Heat shock proteins as modulators and therapeutic targets of chronic disease: an integrated perspective'.

Equal Expansion of Endogenous Transplant-Specific Regulatory T Cell and Recruitment Into the Allograft During Rejection and Tolerance

Despite numerous advances in the definition of a role for regulatory T cells (Tregs) in facilitating experimental transplantation tolerance, and ongoing clinical trials for Treg-based therapies, critical issues related to the optimum dosage, antigen-specificity, and Treg-friendly adjunct immunosuppressants remain incompletely resolved. In this study, we used a tractable approach of MHC tetramers and flow cytometry to define the fate of conventional (Tconvs) and Tregs CD4⁺ T cells that recognize donor 2W antigens presented by I-A^b on donor and recipient antigen-presenting cells (APCs) in a mouse cardiac allograft transplant model. Our study shows that these endogenous, donor-reactive Tregs comparably accumulate in the spleens of recipients undergoing acute rejection or exhibiting costimulation blockade-induced tolerance. Importantly, this expansion was not detected when analyzing bulk splenic Tregs. Systemically, the distinguishing feature between tolerance and rejection was the inhibition of donor-reactive conventional T cell (Tconv) expansion in tolerance, translating into increased percentages of splenic FoxP3⁺ Tregs within the 2W:I-A^b CD4⁺ T cell subset compared to rejection (~35 vs. <5% in tolerance vs. rejection). We further observed that continuous administration of rapamycin, cyclosporine A, or CTLA4-Ig did not facilitate donor-specific Treg expansion, while all three drugs inhibited Tconv expansion. Finally, donor-specific Tregs accumulated comparably in rejecting tolerant allografts, whereas tolerant grafts harbored <10% of the donor-specific Tconv numbers observed in rejecting allografts. Thus, ~80% of 2W:I-A^b CD4⁺ T cells in tolerant allografts expressed FoxP3⁺ compared to ≤10% in rejecting allografts. A similar, albeit lesser, enrichment was observed with bulk graft-infiltrating CD4⁺ cells, where ~30% were FoxP3⁺ in tolerant allografts, compared to ≤10% in rejecting allografts. Finally, we assessed that the phenotype of 2W:I-A^b Tregs and observed that the percentages of cells expressing neuropilin-1 and CD73 were significantly higher in tolerance compared to rejection, suggesting that these Tregs may be functionally distinct. Collectively, the analysis of donor-reactive, but not of bulk, Tconvs and Tregs reveal a systemic signature of tolerance that is stable and congruent with the signature within tolerant allografts. Our data also underscore the importance of limiting Tconv expansion for high donor-specific Tregs:Tconv ratios to be successfully attained in transplantation tolerance.

The role of regulatory T cells, interleukin-10 and in vivo scintigraphy in autoimmune and idiopathic diseases - Therapeutic perspectives and prognosis

Previous studies have demonstrated the expression of the CD25 marker on the surface of naturally occurring T cells (Tregs) of mice, which have a self-reactive cellular profile. Recently, expression of other markers that aid in the identification of these cells has been detected in lymphocyte subtypes of individuals suffering of autoimmune and idiopathic diseases, including: CD25, CTLA-4 (cytotoxic T-lymphocyte antigen 4), HLA-DR (human leukocyte antigen) and Interleukin 10 (IL-10), opening new perspectives for a better understanding of an association between such receptors present on the cell surface and the prognosis of autoimmune diseases. The role of these molecules has already been described in the literature for the modulation of the inflammatory response in infectious and parasitic diseases. Thus, the function, phenotype and frequency of expression of the a-chain receptor of IL-2 (CD25) and IL-10 in lymphocyte subtypes were investigated. Murine models have been used to demonstrate a possible correlation between the expression of the CD25 marker (on the surface of CD4 lymphocytes) and the control of self-tolerance mechanisms. These studies provided support for the presentation of a review of the role of cells expressing IL-2, IL-10, HLA-DR and CTLA-4 receptors in the monitoring of immunosuppression in diseases classified as autoimmune, providing perspectives for understanding peripheral regulation mechanisms and the pathophysiology of these diseases in humans. In addition, a therapeutic approach based on the manipulation of the phenotype of these cells and ways of scintigraphically monitoring the manifestations of these diseases by labeling their receptors is discussed as a perspective. In this paper, we have included the description of experiments in ex vivo regulation of IL-10 and synthesis of thio-sugars and poly-sugars to produce radiopharmaceuticals for monitoring inflammation. These experiments may yield benefits for the treatment and prognosis of autoimmune diseases.

Type I interferon signaling attenuates regulatory T cell function in viral infection and in the tumor microenvironment

Regulatory T cells (Tregs) play a cardinal role in the immune system by suppressing detrimental autoimmune responses, but their role in acute, chronic infectious diseases and tumor microenvironment remains unclear. We recently demonstrated that IFN-α/β receptor (IFNAR) signaling promotes Treg function in autoimmunity. Here we dissected the functional role of IFNAR-signaling in Tregs using Treg-specific IFNAR deficient (IFNAR^fl/flxFoxp3^YFP-Cre) mice in acute LCMV Armstrong, chronic Clone-13 viral infection, and in tumor models. In both viral infection and tumor models, IFNAR^fl/flxFoxp3^YFP-Cre mice Tregs expressed enhanced Treg associated activation antigens. LCMV-specific CD8⁺ T cells and tumor infiltrating lymphocytes from IFNAR^fl/flxFoxp3^YFP-Cre mice produced less antiviral and antitumor IFN-γ and TNF-α. In chronic viral model, the numbers of antiviral effector and memory CD8⁺ T cells were decreased in IFNAR^fl/flxFoxp3^YFP-Cre mice and the effector CD4⁺ and CD8⁺ T cells exhibited a phenotype compatible with enhanced exhaustion. IFNAR^fl/flxFoxp3^YFP-Cre mice cleared Armstrong infection normally, but had higher viral titers in sera, kidneys and lungs during chronic infection, and higher tumor burden than the WT controls. The enhanced activated phenotype was evident through transcriptome analysis of IFNAR^fl/flxFoxp3^YFP-Cre mice Tregs during infection demonstrated differential expression of a unique gene signature characterized by elevated levels of genes involved in suppression and decreased levels of genes mediating apoptosis. Thus, IFN signaling in Tregs is beneficial to host resulting in a more effective antiviral response and augmented antitumor immunity.

Type I interferons (IFNs) play a predominant role in the immune response to infectious pathogens. The cellular targets of IFNs have been difficult to dissect because of the ubiquitous expression of the type I interferon receptor (IFNAR). The immune response of mice to lymphocytic choriomeningitis virus (LCMV) is one of the major models for analyzing the action of IFNs. Regulatory T cells (Tregs) have been implicated in the control of LCMV and it has been proposed that IFN may influence their function. The major goal of this study was to define the contribution of IFN signaling on Treg function during different stages LCMV infection. Tregs from mice with selective deletion of IFNAR manifested enhanced suppressive activity during acute/chronic LCMV infection resulting in increased CD8 T cell anergy, defective generation of memory T cells and persistence of virus. Similar effects of IFNAR signaling in Tregs were seen in a tumor model. We identified a unique set of genes in Tregs modulated by IFN signaling that may contribute to the enhanced suppressive function of IFNAR deficient Tregs. IFNs play a beneficial role during acute/chronic viral infections not only by contributing to viral clearance but also by attenuating the function of Tregs.

Functional Defects of Treg Cells: New Targets in Rheumatic Diseases, Including Ankylosing Spondylitis

PURPOSE OF REVIEW

This study aims to review the advances of Treg cell biology, the functional defects of Treg cells, and the potential strategies for the experimental, preclinical or clinical application of Treg cell therapy in the context of autoimmune/immune-mediated rheumatic diseases.

RECENT FINDINGS

CD4⁺CD25⁺ regulatory T (Treg) cells are a phenotypically and functionally heterogeneous subset of lymphocytes that prevent a variety of autoimmune diseases. As in many autoimmune diseases, the functional defects of Treg cells are supposed to play relevant roles in the pathogenesis and development of systemic lupus erythematosus, rheumatoid arthritis, ankylosing spondylitis, and other autoimmune/immune-mediated rheumatic diseases. Consequently, manipulation and modulation of Treg cells represent a potent strategy for therapeutic benefit in many such diseases. A further understanding of the functional defects of Treg cells in rheumatic diseases will contribute to find new targets and therapies in rheumatic diseases, including ankylosing spondylitis.

Heterogeneity and Stability in Foxp3+ Regulatory T Cells

Foxp3+ regulatory T cells (Tregs) play an indispensable role in controlling tolerance and immunity against self- and foreign antigens. The failure of Tregs to properly function is the direct cause of systemic and chronic inflammation as well as immune suppression. It is now evident that Tregs are highly heterogeneous populations depending on the surface phenotypes, cytokine profiles, and anatomical locations. Yet, our understanding of the cellular and molecular pathways underlying such heterogeneity is very limited. Furthermore, some Tregs lose the phenotype (and suppressive functions) and instead acquire pathogenicity. Since utilizing Tregs as a tool for immunotherapy is being implemented in many clinical settings, it is of utmost importance to understand the precise mechanisms by which the loss of Treg phenotype (and function) is prevented. In this review, both cellular and molecular factors involved in Treg heterogeneity and stability are discussed.

Improved efficacy of allergen-specific immunotherapy by JAK inhibition in a murine model of allergic asthma

Background

Allergen-specific immunotherapy (AIT) is the only curative treatment for type-1 allergies, but sometimes shows limited therapeutic response as well as local and systemic side effects. Limited control of local inflammation and patient symptoms hampers its widespread use in severe allergic asthma.

Objective

Our aim was to evaluate whether AIT is more effective in suppression of local inflammation if performed under the umbrella of short-term non-specific immunomodulation using a small molecule inhibitor of JAK pathways.

Methods

In C57BL/6J mice, a model of ovalbumin (OVA)-induced allergic airway inflammation and allergen-specific immunotherapy was combined with the administration of Tofacitinib (TOFA, a FDA-approved JAK inhibitor) from 48 hours prior to 48 hours after therapeutic OVA-injection. The effect of TOFA on human FOXP3⁺CD4⁺ T cells was studied in vitro.

Results

AIT combined with short-term TOFA administration was significantly more effective in suppressing total cell and eosinophil infiltration into the lung, local cytokine production including IL-1β and CXCL1 and showed a trend for the reduction of IL-4, IL-13, TNF-α and IL-6 compared to AIT alone. Furthermore, TOFA co-administration significantly reduced systemic IL-6, IL-1β and OVA-specific IgE levels and induced IgG1 to the same extent as AIT alone. Additionally, TOFA enhanced the induction of human FOXP3⁺CD4⁺ T cells.

Conclusions

This proof of concept study shows that JAK inhibition did not inhibit tolerance induction, but improved experimental AIT at the level of local inflammation. The improved control of local inflammation might extend the use of AIT in more severe conditions such as polyallergy, asthma and high-risk patients suffering from mastocytosis or anaphylaxis.

Synovial cellular and molecular markers in rheumatoid arthritis

The profound alterations in the structure, cellular composition, and function of synovial tissue in rheumatoid arthritis (RA) are the basis for the persistent inflammation and cumulative joint destruction that are hallmarks of this disease. In RA, the synovium develops characteristics of a tertiary lymphoid organ, with extensive infiltration of lymphocytes and myeloid cells. Concurrently, the fibroblast-like synoviocytes undergo massive hyperplasia and acquire a tissue-invasive phenotype. In this review, we summarize key components of these processes, focusing on recently-described roles of selected molecular markers of these cellular components of RA synovitis.

Parasitic infection as a potential therapeutic tool against rheumatoid arthritis

Parasites, which are a recently discovered yet ancient dweller in human hosts, remain a great public health burden in underdeveloped countries, despite preventative efforts. Rheumatoid arthritis is a predominantly cosmopolitan health problem with drastic morbidity rates, although encouraging progress has been achieved regarding treatment. However, although various types of methods and agents have been applied clinically, their broad usage has been limited by their adverse effects and/or high costs. Sustained efforts have been exerted on the 'hygiene hypothesis' since the 1870s. The immunosuppressive nature of parasitic infections may offer potential insight into therapeutic strategies for rheumatoid arthritis, in which the immune system is overactivated. An increasing number of published papers are focusing on the preventive and/or curative effect of various parasitic infection on rheumatoid arthritis from experimental studies to large-scale epidemiological studies and clinical trials. Therefore, the present review aimed to provide a general literature review on the possible beneficial role of parasitic infection on rheumatoid arthritis.

Breaking Free of Control: How Conventional T Cells Overcome Regulatory T Cell Suppression

Conventional T (Tcon) cells are crucial in shaping the immune response, whether it is protection against a pathogen, a cytotoxic attack on tumor cells, or an unwanted response to self-antigens in the context of autoimmunity. In each of these immune settings, regulatory T cells (Tregs) can potentially exert control over the Tcon cell response, resulting in either suppression or activation of the Tcon cells. Under physiological conditions, Tcon cells are able to transiently overcome Treg-imposed restraints to mount a protective response against an infectious threat, achieving clonal expansion, differentiation, and effector function. However, evidence has accumulated in recent years to suggest that Tcon cell resistance to Treg-mediated suppression centrally contributes to the pathogenesis of autoimmune disease. Tipping the balance too far in the other direction, cancerous tumors utilize Tregs to establish an overly suppressive microenvironment, preventing antitumor Tcon cell responses. Given the wide-ranging clinical importance of the Tcon/Treg interaction, this review aims to provide a better understanding of what determines whether a Tcon cell is susceptible to Treg-mediated suppression and how perturbations to this finely tuned balance play a role in pathological conditions. Here, we focus in detail on the complex array of factors that confer Tcon cells with resistance to Treg suppression, which we have divided into two categories: (1) extracellular factor-mediated signaling and (2) intracellular signaling molecules. Further, we explore the therapeutic implications of manipulating the phosphatidylinositol-3 kinase (PI3K)/Akt signaling pathway, which is proposed to be the convergence point of signaling pathways that mediate Tcon resistance to suppression. Finally, we address important unresolved questions on the timing and location of acquisition of resistance, and the stability of the “Treg-resistant” phenotype.

Tregalizumab - A Monoclonal Antibody to Target Regulatory T Cells

Regulatory T cells (Tregs) represent a subpopulation of CD4⁺ T cells, which are essential for the maintenance of immunological tolerance. The absence or dysfunction of Tregs can lead to autoimmunity and allergies. The restoration of functional Tregs and/or Treg cell numbers represents a novel and attractive approach for the treatment of autoimmune diseases, e.g., rheumatoid arthritis (RA). The CD4 cell surface receptor is a target for modulation of T cell function. Monoclonal antibodies (mAbs) against CD4 have previously been tested for the treatment of autoimmune diseases, including RA. Furthermore, in model systems, anti-CD4 antibodies are able to induce tolerance and mediate immunomodulatory effects through a variety of mechanisms. Despite the availability of innovative and effective therapies for RA, many patients still have persistently active disease or experience adverse events that can limit use. A growing body of evidence suggests that Treg modulation could offer a new therapeutic strategy in RA and other autoimmune disorders. Here, we describe tregalizumab (BT-061), which is a novel, non-depleting IgG1 mAb that binds to a unique epitope of CD4. Tregalizumab represents the first humanized anti-CD4 mAb that selectively induces Treg activation.

In vivo activation of Treg cells with a CD28 superagonist prevents and ameliorates chronic destructive arthritis in mice

Although regulatory T (Treg) cells are necessary to prevent autoimmune diseases, including arthritis, whether Treg cells can ameliorate established inflammatory disease is controversial. Using the glucose-6-phosphate isomerase (G6PI)-induced arthritis model in mice, we aimed to determine the therapeutic efficacy of increasing Treg cell number and function during chronic destructive arthritis. Chronic destructive arthritis was induced by transient depletion of Treg cells prior to immunization with G6PI. At different time points after disease induction, mice were treated with a CD28 superagonistic antibody (CD28SA). CD28SA treatment during the induction phase of arthritis ameliorated the acute signs of arthritis and completely prevented the development of chronic destructive arthritis. CD28SA treatment of mice with fully developed arthritis induced a significant reduction in clinical and histological signs of arthritis. When given during the chronic destructive phase of arthritis, 56 days after disease induction, CD28SA treatment resulted in a modest reduction of clinical signs of arthritis and a reduction in histopathological signs of joint inflammation. Our data show that increasing the number and activation of Treg cells by a CD28SA is therapeutically effective in experimental arthritis.

The Interplay Between Monocytes/Macrophages and CD4(+) T Cell Subsets in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by inflammation of the synovial lining (synovitis). The inflammation in the RA joint is associated with and driven by immune cell infiltration, synovial hyperproliferation, and excessive production of proinflammatory mediators, such as tumor necrosis factor α (TNFα), interferon γ (IFNγ), interleukin (IL)-1β, IL-6, and IL-17, eventually resulting in damage to the cartilage and underlying bone. The RA joint harbors a wide range of immune cell types, including monocytes, macrophages, and CD4(+) T cells (both proinflammatory and regulatory). The interplay between CD14(+) myeloid cells and CD4(+) T cells can significantly influence CD4(+) T cell function, and conversely, effector vs. regulatory CD4(+) T cell subsets can exert profound effects on monocyte/macrophage function. In this review, we will discuss how the interplay between CD4(+) T cells and monocytes/macrophages may contribute to the immunopathology of RA.

IL-1R1 is expressed on both Helios(+) and Helios(-) FoxP3(+) CD4(+) T cells in the rheumatic joint

Synovial fluid from rheumatic joints displays a well-documented enrichment of forkhead box protein 3 (FoxP3)(+) regulatory T cells (tissue Tregs ). However, we have previously demonstrated that the mere frequency of FoxP3 expressing cells cannot predict suppressive function. Instead, extrinsic factors and the functional heterogeneity of FoxP3(+) Tregs complicate the picture. Here, we investigated FoxP3(+) Tregs from blood and synovial fluid of patients with rheumatic disease in relation to Helios expression by assessing phenotypes, proliferative potential and cytokine production by flow cytometry. Our aim was to investigate the discriminatory potential of Helios when studying FoxP3(+) Tregs in an inflammatory setting. We demonstrate that the majority of the synovial FoxP3(+) CD4(+) T cells in patients with inflammatory arthritis expressed Helios. Helios(+) FoxP3(+) Tregs displayed a classical Treg phenotype with regard to CD25 and cytotoxic T lymphocyte-associated antigen (CTLA)-4 expression and a demethylated Treg -specific demethylated region (TSDR). Furthermore, Helios(+) FoxP3(+) T cells were poor producers of the effector cytokines interferon (IFN)-γ and tumour necrosis factor (TNF), as well as of the anti-inflammatory cytokine interleukin (IL)-10. The less abundant Helios(-) FoxP3(+) T cell subset was also enriched significantly in the joint, displayed a overlapping phenotype to the double-positive Treg cells with regard to CTLA-4 expression, but differed by their ability to secrete IL-10, IFN-γ and TNF upon T cell receptor (TCR) cross-linking. We also demonstrate a striking enrichment of IL-1R1 expression in synovial CD4(+) T cells that was restricted to the CD25-expressing FoxP3 population, but independent of Helios. IL-1R1 expression appears to define a tissue Treg cell phenotype together with the expression of CD25, glucocorticoid-induced TNF receptor family-related gene (GITR) and CTLA-4.

Altered immunoregulation in rheumatoid arthritis: the role of regulatory T cells and proinflammatory Th17 cells and therapeutic implications

In recent years several studies investigated the role of T lymphocyte subpopulations in the pathogenesis of rheumatoid arthritis (RA). Pathogenic Th17 cells mediate pannus growth, osteoclastogenesis, and synovial neoangiogenesis; hence they are key players in the development of the disease. On the other hand, regulatory T (Treg) cells are a T cell subset whose peculiar function is to suppress autoreactive lymphocytes. The imbalance between Th17 and Treg cells has been identified as a crucial event in the pathogenesis of RA. In addition, the effects of currently employed RA therapeutic strategies on these lymphocyte subpopulations have been extensively investigated. This review article aims to discuss current knowledge on Treg and Th17 cells in RA and possible implications of their therapeutic targeting in this disorder.

Nonapoptotic and extracellular activity of granzyme B mediates resistance to regulatory T cell (Treg) suppression by HLA-DR-CD25hiCD127lo Tregs in multiple sclerosis and in response to IL-6

In autoimmune patients, regulatory T cells (Tregs) are increasingly found to be unable to suppress patient-derived T cells, an outcome referred to as Treg resistance. In this study, we show that CD4 T cells from patients with multiple sclerosis resist suppression by patient-derived or healthy donor-derived ex vivo Tregs. Importantly, we report that granzyme B (GzmB) contributes to this Treg resistance via a novel, apoptosis-independent mechanism. We show that memory CD4(+)CD127(lo)FOXP3(+) Treg subsets do not express GzmB, whereas activated, nonregulatory CD4 T cells isolated from patients with multiple sclerosis express higher levels of GzmB than do cells from healthy donors. In contrast to the intracellular GzmB that mediates apoptosis, GzmB can be found in extracellular fluids where it is hypothesized to regulate other cellular processes. In this study, we show that providing extracellular GzmB strongly inhibits Treg suppression, without altering Treg viability. However, when GzmB and GzmB-specific inhibitor are both provided to the cocultures, Treg suppression occurs. Thus, these data suggest that a novel activity of extracellular GzmB is to regulate Treg suppression. Additionally, we find that the suppression-abrogating cytokine IL-6 augments GzmB expression by human CD4 T cells, and it inhibits Treg suppression via this nonapoptotic GzmB-mediated mechanism. Lastly, in examining the mechanism whereby GzmB inhibits Treg function, we show that extracellular GzmB reduces Treg expression of CD39 and programmed death ligand 1. Collectively, these data indicate that extracellular GzmB plays an unexpected, nonapoptotic role in regulating Treg suppression and suggest that inactivation of specifically the extracellular activity of GzmB may be an efficacious therapeutic in autoimmunity.

Rebamipide attenuates autoimmune arthritis severity in SKG mice via regulation of B cell and antibody production

Oxidative stress is involved in the pathophysiology of rheumatoid arthritis (RA). We investigated the therapeutic potential of rebamipide, a gastroprotective agent with a property of reactive oxygen species scavenger, on the development of inflammatory polyarthritis and the pathophysiological mechanisms by which rebamipide might confer anti-arthritic effects in SKG mice, an animal model of RA. Intraperitoneal (i.p.) injection of rebamipide attenuated the severity of clinical and histological arthritis. Rebampide treatment reduced the number of T helper type 1 (Th1), Th2, Th17, inducible T cell co-stimulator (ICOS)(+) follicular helper T (Tfh) transitional type (T2) and mature B cells in the spleen, but increased the number of regulatory T (Treg ), CD19(+) CD1d(high) CD5(high) , CD19(+) CD25(high) forkhead box protein 3 (FoxP3)(+) regulatory B (Breg ) cells, memory B cells, and transitional type 1 (T1) B cells. In addition, flow cytometric analysis revealed significantly decreased populations of FAS(+) GL-7(+) germinal centre B cells and B220(-) CD138(+) plasma cells in the spleens of rebamipide-treated SKG mice compared to controls. Rebamipide decreased germinal centre B cells and reciprocally induced Breg cells in a dose-dependent manner in vitro. Rebamipide-induced Breg cells had more suppressive capacity in relation to T cell proliferation and also inhibited Th17 differentiation from murine CD4(+) T cells. Together, these data show that i.p. administration of rebamipide suppresses arthritis severity by inducing Breg and Treg cells and suppressing Tfh and Th17 cells in a murine model of RA.

Impaired suppressive capacity of activation-induced regulatory B cells in systemic lupus erythematosus

OBJECTIVE

B cells with immunoregulatory properties (Breg cells) have been described in mice, but their role in the control of human immune responses is not well defined. We recently identified a human population of activated FSC(high) B cells that exhibited regulatory activity toward T helper cells. The aim of the present study was to test such induced Breg (iBreg) cells in patients with autoimmune disease.

METHODS

Purified CD19+FSC(high) B cells derived from patients with systemic lupus erythematosus (SLE) or from healthy donors, which were activated via their B cell receptor, were cocultured with CD3-stimulated CD4+ T helper cells from SLE patients or healthy donors. (3) H-thymidine incorporation, flow cytometry, and enzyme-linked immunosorbent assay (ELISA) were used to analyze proliferation, cytokine secretion, and surface marker expression.

RESULTS

Although under costimulatory conditions, FSC(high) SLE B cells supported the proliferation of healthy donor T cells to a similar extent as donor B cells, their regulatory function was significantly diminished in B cell suppressor assays. Similar effects were seen when SLE T cells were used, confirming that SLE T cells were equally susceptible to iBreg cell signals as healthy donor T cells and that SLE iBreg cell defects were independent of T cell origin. B cell viability and expression of surface markers (CD25, CD80, and B7-H1) or cytokines (interleukin-6 [IL-6], tumor necrosis factor α, and IL-10) were comparable in the two B cell populations. There was no correlation between the extent of iBreg cell-induced inhibition and disease activity. CD19+FSC(high) B cells from patients with another systemic autoimmune disease, granulomatosis with polyangiitis (Wegener's) (GPA), exhibited no regulatory defects, which suggests that the iBreg cell defects were SLE-specific and not a general consequence of autoimmunity or inflammation.

CONCLUSION

Induced Breg cells from SLE patients, but not GPA patients, are less effective in the control of T helper cell proliferation, which supports the reported skewed B cell repertoire in SLE. The malfunctioning SLE iBreg cells might allow the overstimulation of immune responses and contribute to the initiation and/or perpetuation of disease.

Regulatory T-cell homeostasis: steady-state maintenance and modulation during inflammation

Regulatory T (Treg) cells play a vital role in the prevention of autoimmunity and the maintenance of self-tolerance, but these cells also have an active role in inhibiting immune responses during viral, bacterial, and parasitic infections. Although excessive Treg activity can lead to immunodeficiency, chronic infection, and cancer, too little Treg activity results in autoimmunity and immunopathology and impairs the quality of pathogen-specific responses. Recent studies have helped define the homeostatic mechanisms that support the diverse pool of peripheral Treg cells under steady-state conditions and delineate how the abundance and function of Treg cells changes during inflammation. These findings are highly relevant for developing effective strategies to manipulate Treg cell activity to promote allograft tolerance and treat autoimmunity, chronic infection, and cancer.

Update on research and clinical translation on specific clinical areas: From bench to bedside: How insight in immune pathogenesis can lead to precision medicine of severe juvenile idiopathic arthritis

Despite the enormous progress in the treatment of juvenile idiopathic arthritis (JIA), innovations based on true bench-to-bedside research, performed in JIA patients, are still scarce. This chapter describes novel developments in which clinical innovations go hand in hand with basic discoveries. For the purpose of this review, we will mainly focus on developments in severe forms of JIA, most notably systemic JIA and polyarticular JIA. However, also in less severe forms of JIA, such as oligoarticular JIA, better insight will help to improve diagnosis and treatment. Facilitating the transition from bench to bedside will prove crucial for addressing the major challenges in JIA management. If successful, it will set new standards for a safe, targeted and personalized therapeutic approach for children with JIA.

Cytokine expression and cytokine-based T cell profiling in South Indian rheumatoid arthritis

Rheumatoid arthritis (RA), a chronic inflammatory disease affects up to 1% of the general population. Early diagnosis and treatment are limited by the absence of specific and reliable diagnostic/prognostic biomarkers. This study was carried out in 48 Tamil South Indian RA patients and 49 healthy controls (HC) to identify any cytokine signature(s) that could potentially serve as biomarkers. Expression profiles of Th1, Th2, Th17 and Tregs cell type-specifying cytokines and transcription factors were analyzed using real time quantitative PCR (qPCR) assay. To explore if such expression profiles mirror their steady state plasma levels, a bead-based multiplex fluorescent assay was carried out. We found that the expression of transcription factors T-bet (for Th1), GATA-3 (for Th2) and FoxP3 (for Tregs) were significantly lower in patients than in healthy controls (P<0.0001) similar to lowering of IFNγ (P=0.004) and IL-10 (P=0.04). The transcript levels of IL-12p40 and TNF-α were higher among patients as compared to HC (P<0.0001 and P=0.02, respectively). Circulating levels of assessed cytokines were in general higher in RA patients as compared to controls. These alterations in the expression of transcription factors and cytokines highlight the underlying dysregulation of T cell subsets in RA that reflects a predominantly inflammatory phenotype. Despite dissecting these cellular and molecular processes, no specific signature that could be of diagnostic and/or prognostic value was identified. Additional longitudinal follow-up studies, especially on newly diagnosed treatment-naïve patients are warranted to uncover clinically useful biomarkers of RA.

Myasthenia Gravis: paradox versus paradigm in autoimmunity

Myasthenia Gravis (MG) is a paradigm of organ-specific autoimmune disease (AID). It is mediated by antibodies that target the neuromuscular junction. The purpose of this review is to place MG in the general context of autoimmunity, to summarize the common mechanisms between MG and other AIDs, and to describe the specific mechanisms of MG. We have chosen the most common organ-specific AIDs to compare with MG: type 1 diabetes mellitus (T1DM), autoimmune thyroid diseases (AITD), multiple sclerosis (MS), some systemic AIDs (systemic lupus erythematous (SLE), rheumatoid arthritis (RA), Sjogren's syndrome (SS)), as well as inflammatory diseases of the gut and liver (celiac disease (CeD), Crohn's disease (CD), and primary biliary cirrhosis (PBC)). Several features are similar between all AIDs, suggesting that common pathogenic mechanisms lead to their development. In this review, we address the predisposing factors (genetic, epigenetic, hormones, vitamin D, microbiota), the triggering components (infections, drugs) and their interactions with the immune system [1,2]. The dysregulation of the immune system is detailed and includes the role of B cells, Treg cells, Th17 and cytokines. We particularly focused on the role of TNF-α and interferon type I whose role in MG is very analogous to that in several other AIDS. The implication of AIRE, a key factor in central tolerance is also discussed. Finally, if MG is a prototype of AIDS, it has a clear specificity compared to the other AIDS, by the fact that the target organ, the muscle, is not the site of immune infiltration and B cell expansion, but exclusively that of antibody-mediated pathogenic mechanisms. By contrast, the thymus in the early onset subtype frequently undergoes tissue remodeling, resulting in the development of ectopic germinal centers surrounded by high endothelial venules (HEV), as observed in the target organs of many other AIDs.

Protection against collagen-induced arthritis in mice afforded by the parasitic worm product, ES-62, is associated with restoration of the levels of interleukin-10-producing B cells and reduced plasma cell infiltration of the joints

We have previously reported that ES-62, a molecule secreted by the parasitic filarial nematode Acanthocheilonema viteae, protects mice from developing collagen-induced arthritis (CIA). Together with increasing evidence that worm infection may protect against autoimmune conditions, this raises the possibility that ES-62 may have therapeutic potential in rheumatoid arthritis and hence, it is important to fully understand its mechanism of action. To this end, we have established to date that ES-62 protection in CIA is associated with suppressed T helper type 1 (Th1)/Th17 responses, reduced collagen-specific IgG2a antibodies and increased interleukin-10 (IL-10) production by splenocytes. IL-10-producing regulatory B cells have been proposed to suppress pathogenic Th1/Th17 responses in CIA: interestingly therefore, although the levels of IL-10-producing B cells were decreased in the spleens of mice with CIA, ES-62 was found to restore these to the levels found in naive mice. In addition, exposure to ES-62 decreased effector B-cell, particularly plasma cell, infiltration of the joints, and such infiltrating B cells showed dramatically reduced levels of Toll-like receptor 4 and the activation markers, CD80 and CD86. Collectively, this induction of hyporesponsiveness of effector B-cell responses, in the context of the resetting of the levels of IL-10-producing B cells, is suggestive of a modulation of the balance between effector and regulatory B-cell responses that may contribute to ES-62-mediated suppression of CIA-associated inflammation and inhibition of production of pathogenic collagen-specific IgG2a antibodies.

The expanding role of IL-7 and thymic stromal lymphopoietin as therapeutic target for rheumatoid arthritis

INTRODUCTION

The discovery of IL-7 and thymic stromal lymphopoietin (TSLP) has been a major step in the understanding of arthritis. IL-7 amplifies the inflammation induced by other cytokines, primarily TNF. In animal models of arthritis, inhibition of IL-7 limits inflammation and joint erosion. TSLP is an IL-7-like cytokine that triggers dendritic cell-mediated Th2-type inflammatory responses and is considered as a master switch for allergic inflammation. TSLP is a downstream molecule of TNF-α and as such may be involved in the pathophysiology of inflammatory arthritis.

AREAS COVERED

This review summarizes current knowledge of the role of IL-7 and TSLP derived from both animal models and studies in patients with rheumatoid arthritis (RA). The emergence of IL-7 blockade as a future therapy in RA is highlighted, along with the potential goals and limitations of this therapeutic approach. The write-up also highlights the functional capacities of TSLP in arthritis.

EXPERT OPINION

Evidences suggest important roles for IL-7 and TSLP in the pathogenesis of RA and can be viewed as potential therapeutic targets. Regulation of these at genetic level is a promising investigational area. Given the difficulty in reconstituting T cells in patients with RA, therapeutic approaches that minimize the elimination of T cells are likely to be more desirable.