Early rheumatoid arthritis is associated with a deficit in the CD4+CD25high regulatory T cell population in peripheral blood

Osteoimmunology: The Crosstalk between T Cells, B Cells, and Osteoclasts in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an ongoing inflammatory condition that affects the joints and can lead to severe damage to cartilage and bones, resulting in significant disability. This condition occurs when the immune system becomes overactive, causing osteoclasts, cells responsible for breaking down bone, to become more active than necessary, leading to bone breakdown. RA disrupts the equilibrium between osteoclasts and osteoblasts, resulting in serious complications such as localized bone erosion, weakened bones surrounding the joints, and even widespread osteoporosis. Antibodies against the receptor activator of nuclear factor-κB ligand (RANKL), a crucial stimulator of osteoclast differentiation, have shown great effectiveness both in laboratory settings and actual patient cases. Researchers are increasingly focusing on osteoclasts as significant contributors to bone erosion in RA. Given that RA involves an overactive immune system, T cells and B cells play a pivotal role by intensifying the immune response. The imbalance between Th17 cells and Treg cells, premature aging of T cells, and excessive production of antibodies by B cells not only exacerbate inflammation but also accelerate bone destruction. Understanding the connection between the immune system and osteoclasts is crucial for comprehending the impact of RA on bone health. By delving into the immune mechanisms that lead to joint damage, exploring the interactions between the immune system and osteoclasts, and investigating new biomarkers for RA, we can significantly improve early diagnosis, treatment, and prognosis of this condition.

Conventional Tregs in treatment-naïve rheumatoid arthritis are deficient in suppressive function with an increase in percentage of CXCR3 and CCR6 expressing Tregs

In rheumatoid arthritis (RA), immune homeostasis is maintained by T regulatory cells (Tregs) that in an inflammatory milieu can change towards T-helper-like phenotypes (Th-like Tregs). Our aim was to examine the phenotypic and functional characteristics of CD4+CD25+CD127lo/- Tregs, Th-like Tregs and T effector (Teff) cells in the peripheral blood (PB) and synovial fluid (SF) of treatment-naïve early RA, as compared to osteoarthritis (OA) and healthy control (HC) peripheral blood. Frequencies of Tregs, CXCR3, CCR6 expressing Tregs (Th-like Tregs), and Teff cells were analyzed using flow cytometry in RA (n = 80), OA (n = 20), and HC (n = 40). Cytokine concentrations of the respective T cell subsets in plasma and SF were measured using flow cytometric bead array. Tregs sorted from RA and HC PB using magnetic beads were analyzed for functional capacities by CFSE proliferation assay and FOXP3 gene expression using real-time PCR. We observed that the frequencies of Th17 cells in PB and SF were significantly higher in RA when compared to HC, whereas Tregs were lower in PB and high in SF compared to HC and OA respectively. Th1- and Th17-related pro-inflammatory cytokines IL12p70, INF-γ, TNF-α, and IL-6, and IL-17A were significantly higher in the plasma and SF of RA. Tregs expressing CXCR3 (Th1-like Tregs) and CCR6 (Th17-like Treg) were significantly higher in PB and SF of RA compared to controls and was positively associated with seropositivity and disease activity. Treg cells isolated from peripheral blood of RA showed decreased function and reduced FOXP3 gene expression compared to HC. In our study, we have demonstrated higher frequencies of Th1 and Th17 cells and increased circulatory and SF pro-inflammatory cytokines (IL12P70, INF-γ, IL-6, IL-17A, and TNF-α) in RA. This inflammatory milieu might alter total Tregs frequencies and influence conversion of Tregs into Th-like Tregs.

The Role of Extracellular Vesicles in the Pathogenesis and Treatment of Rheumatoid Arthritis and Osteoarthritis

Cells can communicate with each other through extracellular vesicles (EVs), which are membrane-bound structures that transport proteins, lipids and nucleic acids. These structures have been found to mediate cellular differentiation and proliferation apoptosis, as well as inflammatory responses and senescence, among others. The cargo of these vesicles may include immunomodulatory molecules, which can then contribute to the pathogenesis of various diseases. By contrast, EVs secreted by mesenchymal stem cells (MSCs) have shown important immunosuppressive and regenerative properties. Moreover, EVs can be modified and used as drug carriers to precisely deliver therapeutic agents. In this review, we aim to summarize the current evidence on the roles of EVs in the progression and treatment of rheumatoid arthritis (RA) and osteoarthritis (OA), which are important and prevalent joint diseases with a significant global burden.

T cells in health and disease

T cells are crucial for immune functions to maintain health and prevent disease. T cell development occurs in a stepwise process in the thymus and mainly generates CD4⁺ and CD8⁺ T cell subsets. Upon antigen stimulation, naïve T cells differentiate into CD4⁺ helper and CD8⁺ cytotoxic effector and memory cells, mediating direct killing, diverse immune regulatory function, and long-term protection. In response to acute and chronic infections and tumors, T cells adopt distinct differentiation trajectories and develop into a range of heterogeneous populations with various phenotype, differentiation potential, and functionality under precise and elaborate regulations of transcriptional and epigenetic programs. Abnormal T-cell immunity can initiate and promote the pathogenesis of autoimmune diseases. In this review, we summarize the current understanding of T cell development, CD4⁺ and CD8⁺ T cell classification, and differentiation in physiological settings. We further elaborate the heterogeneity, differentiation, functionality, and regulation network of CD4⁺ and CD8⁺ T cells in infectious disease, chronic infection and tumor, and autoimmune disease, highlighting the exhausted CD8⁺ T cell differentiation trajectory, CD4⁺ T cell helper function, T cell contributions to immunotherapy and autoimmune pathogenesis. We also discuss the development and function of γδ T cells in tissue surveillance, infection, and tumor immunity. Finally, we summarized current T-cell-based immunotherapies in both cancer and autoimmune diseases, with an emphasis on their clinical applications. A better understanding of T cell immunity provides insight into developing novel prophylactic and therapeutic strategies in human diseases.

Regulatory T cells in peripheral tissue tolerance and diseases

Maintenance of peripheral tolerance by CD4+Foxp3+ regulatory T cells (Tregs) is essential for regulating autoreactive T cells. The loss of function of Foxp3 leads to autoimmune disease in both animals and humans. An example is the rare, X-linked recessive disorder known as IPEX (Immune Dysregulation, Polyendocrinopathy, Enteropathy X-linked) syndrome. In more common human autoimmune diseases, defects in Treg function are accompanied with aberrant effector cytokines such as IFNγ. It has recently become appreciated that Tregs plays an important role in not only maintaining immune homeostasis but also in establishing the tissue microenvironment and homeostasis of non-lymphoid tissues. Tissue resident Tregs show profiles that are unique to their local environments which are composed of both immune and non-immune cells. Core tissue-residence gene signatures are shared across different tissue Tregs and are crucial to homeostatic regulation and maintaining the tissue Treg pool in a steady state. Through interaction with immunocytes and non-immunocytes, tissue Tregs exert a suppressive function via conventional ways involving contact dependent and independent processes. In addition, tissue resident Tregs communicate with other tissue resident cells which allows Tregs to adopt to their local microenvironment. These bidirectional interactions are dependent on the specific tissue environment. Here, we summarize the recent advancements of tissue Treg studies in both human and mice, and discuss the molecular mechanisms that maintain tissue homeostasis and prevent pathogenesis.

High-throughput Treg cell receptor sequencing reveals differential immune repertoires in rheumatoid arthritis with kidney deficiency

Background

Regulatory T (Treg) cells are important immune cells that are regulated by adaptive immunity in the composition of Treg-cell subsets and T-cell receptors (TCRs). Treg cells are related to most autoimmune diseases, such as rheumatoid arthritis (RA). In traditional Chinese medicine (TCM), RA is typically attributed to kidney deficiency (KD) associated with the immunosenescence that causes immune dysfunction and the impaired function of Treg cells. So far, however, no mechanism related to KD and immune repertoires has been identified in RA.

Methods

Flow cytometry and high-throughput Treg-cell receptor sequencing were used to investigate the amount of different Treg-cell subsets and the diversity of TCRs between RA patients and healthy subjects, as well as between KD RA and non-KD RA patients. RT-qPCR was used to validate the high-throughput sequencing results.

Results

The data showed that the amount of naïve Treg cells in KD patients was less than in non-KD RA patients (P = 0.004) with no significant differences observed between other subsets. In the TCR of Treg cells, the length of complementarity determining region 3 (CDR3) was low and clonotypes increased in the KD group compared with the non-KD group. The diversity and abundance of Treg TCRs were low, as determined by the Hill number. In addition, several V(D)J combinations, such as T-cell receptor beta variable 7-2 (TRBV7-2), TRBV11-1, TRBV13, TRBV15, and TRBJ2-3, varied significantly between the two groups, indicating that KD causes Treg dysfunction. RT-qPCR shows that FOXP3 expression in peripheral blood Treg is lower in KD than in non-KD.

Conclusion

The results demonstrate the close correlation between KD and immune repertoires in RA and provide a new evaluation method for RA in TCM.

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.

Regulatory T cells in rheumatoid arthritis: functions, development, regulation, and therapeutic potential

Rheumatoid arthritis (RA) is an autoimmune disease that mainly affects the joints but also leads to systemic inflammation. Auto-reactivity and dysregulation of self-tolerance are thought to play a vital role in disease onset. In the pathogenesis of autoimmune diseases, disturbed immunosuppressive properties of regulatory T cells contribute to the dysregulation of immune homeostasis. In RA patients, the functions of Treg cells and their frequency are reduced. Therefore, focusing on the re-establishment of self-tolerance by increasing Treg cell frequencies and preventing a loss of function is a promising strategy for the treatment of RA. This approach could be especially beneficial for those patients who do not respond well to current therapies. In this review, we summarize and discuss the current knowledge about the function, differentiation and regulation of Treg cells in RA patients and in animal models of autoimmune arthritis. In addition, we highlight the therapeutic potential as well as the challenges of Treg cell targeting treatment strategies.

Tregs in Autoimmunity: Insights Into Intrinsic Brake Mechanism Driving Pathogenesis and Immune Homeostasis

CD4⁺CD25^highFoxp3⁺ regulatory T-cells (Tregs) are functionally characterized for their ability to suppress the activation of multiple immune cell types and are indispensable for maintaining immune homeostasis and tolerance. Disruption of this intrinsic brake system assessed by loss of suppressive capacity, cell numbers, and Foxp3 expression, leads to uncontrolled immune responses and tissue damage. The conversion of Tregs to a pathogenic pro-inflammatory phenotype is widely observed in immune mediated diseases. However, the molecular mechanisms that underpin the control of Treg stability and suppressive capacity are incompletely understood. This review summarizes the concepts of T_reg cell stability and T_reg cell plasticity highlighting underlying mechanisms including translational and epigenetic regulators that may enable translation to new therapeutic strategies. Our enhanced understanding of molecular mechanism controlling Tregs will have important implications into immune homeostasis and therapeutic potential for the treatment of immune-mediated diseases.

Circulating inflammatory cell profiling and periodontitis: A systematic review and meta-analysis

Inflammation is a key driver of common noncommunicable diseases. Among common triggers of inflammation, chronic gingival inflammation (periodontitis) triggers a consistent humoral host inflammatory response, but little is known on its impact on circulating inflammatory cell profiles. We aimed to systematically appraise all the evidence linking periodontitis and its treatment to circulating inflammatory cell profiles. From 6 databases, 157 studies were eligible for qualitative synthesis and 29 studies for meta-analysis. Our meta-analysis showed that participants with periodontitis exhibited a significant mean increase in circulating CD4⁺ , CD4⁺ CD45RO⁺ , IFNγ-expressing CD4⁺ and CD8⁺ T cells, CD19⁺ CD27⁺ and CD5⁺ B cells, CD14⁺ CD16⁺ monocytes, and CD16⁺ neutrophils but decrease in CD8⁺ T and CD14⁺⁺ CD16^- monocytes. Our qualitative synthesis revealed that peripheral blood neutrophils of patients with periodontitis consistently showed elevated production of reactive oxygen species (ROS) when compared with those of healthy controls. Some evidence suggested that the treatment of periodontitis reversed the exaggerated ROS production, but limited and inconclusive data were found on several circulating inflammatory cell profiling. We conclude that periodontitis and its treatment are associated with minor but consistent alterations in circulating inflammatory cell profiles. These changes could represent key mechanisms explaining the association of periodontitis with other comorbidities such as cardiovascular disease, diabetes, and rheumatoid arthritis.

B cell depletion treatment decreases Th17 cells in patients with rheumatoid arthritis

INTRODUCTION

We aimed to evaluate for any possible effects of treatment with rituximab (RTX) on the peripheral Th17 and Treg subpopulations in patients with rheumatoid arthritis (RA).

PATIENTS AND METHODS

We analyzed 16 patients with RA initiating RTX treatment, 11 patients with RA initiating abatacept treatment, 11 patients with RA treated with other medications, 8 patients with other autoimmune rheumatic diseases initiating RTX, and 14 healthy volunteers. Th17 cells (CD4⁺IL23R⁺IL17A⁺) and Treg cells (CD4⁺CD25^hiFoxP3⁺) were evaluated flow-cytometrically.

RESULTS

Th17 cells from patients treated with RTX decreased significantly at weeks 8 and 16 (mean ± SEΜ: 3.01% ± 0.54℅ CD4⁺ cells at week 0 vs. 1.53% ± 0.24℅ at week 8 vs 1.10% ± 0.20℅ at week 16, p = 0.0004). Reductions of Th17 cells were evident in clinical responders (DAS28 score ≤ 3.2), ACPA (+) and RF (-) patients; circulating Tregs remained stable. Th17 and Tregs were not affected by ABA treatment or by changes in disease activity. Tregs, but not Th17 cells, decreased following treatment with RTX in patients with other autoimmune diseases (0.75% ± 0.16% at week 0 vs. 0.43% ± 0.16% at week 8, p = 0.033).

CONCLUSION

RTX-induced B cell depletion results in a significant reduction of circulating Th17 cell percentages, whereas it has no effect on Tregs of patients with RA. This reduction of Th17 cells was evident particularly in responders to RTX treatment, ACPA+ and RF (-) patients with RA.

Regulatory T Cells and Inflammatory Mediators in Autoimmune Disease

Regulatory T cells (Tregs) play a critical role in regulating tissue inflammation. Reduced Treg numbers and/or suppressive function contribute to autoimmune disease. Tregs can adopt the transcriptional programming of T helper (Th) type-1/2/17 cells to optimally suppress these subsets. Under specific conditions, these Th-like Tregs lose suppressive capacity and release proinflammatory cytokines to promote inflammation. This Treg plasticity depends on inflammatory mediators in the local environment. In this study, we review how cytokines impact Treg function and may contribute to autoimmune disease. A comprehensive understanding of Th-like Tregs may elucidate novel and more focused therapeutic approaches.

Reactive oxygen species-responsive dendritic cell-derived exosomes for rheumatoid arthritis

Although tolerogenic dendritic cell-derived exosomes (TolDex) have emerged as promising therapeutics for rheumatoid arthritis (RA), their clinical applications have been hampered by their poor in vivo disposition after systemic administration. Herein, we report the development of stimuli-responsive TolDex that induces lesion-specific immunoregulation in RA. Responsiveness to reactive oxygen species (ROS), a physiological stimulus in the RA microenvironment, was conferred on TolDex by introducing a thioketal (TK) linker-embedded poly(ethylene glycol) (PEG) on TolDex surface via hydrophobic insertion. The detachment of PEG following overproduction of ROS facilitates the cellular uptake of ROS-responsive TolDex (TKDex) into activated immune cells. Notably, TolDex and TKDex downregulated CD40 in mature dendritic cells (mDCs) and regulated secretion of pro-inflammatory cytokines, including tumor necrosis factor (TNF)-α and interleukin-6 (IL-6) at the cellular level. In the collagen-induced arthritis (CIA) mouse model, PEG prolonged the blood circulation of TKDex following intravenous administration and enhanced their accumulation in the joints. In addition, TKDex decreased IL-6, increased transforming growth factor-β, and induced the CD4⁺CD25⁺Foxp3⁺ regulatory T cells in CIA mice. Overall, ROS-responsive TolDex might have potential as therapeutic agents for RA. STATEMENT OF SIGNIFICANCE: Tolerogenic dendritic cell-derived exosomes (TolDex) are emerging immunoregulators of autoimmune diseases, including rheumatoid arthritis (RA). However, their lack of long-term stability and low targetability are still challenging. To overcome these issues, we developed reactive oxygen species (ROS)-responsive TolDex (TKDex) by incorporating the ROS-sensitive functional group-embedded poly(ethylene glycol) linker into the exosomal membrane of TolDex. Surface-engineered TKDex were internalized in mature DCs because of high ROS-sensitivity and enhanced accumulation in the inflamed joint in vivo. Further, for the first time, we investigated the potential mechanism of action of TolDex relevant to CD40 downregulation and attenuation of tumor necrosis factor (TNF)-α secretion. Our strategy highlighted the promising nanotherapeutic effects of stimuli-sensitive TolDex, which induces immunoregulation.

Disruptive Selection of Human Immunostimulatory and Immunosuppressive Genes Both Provokes and Prevents Rheumatoid Arthritis, Respectively, as a Self-Domestication Syndrome

Using our previously published Web service SNP_TATA_Comparator, we conducted a genome-wide study of single-nucleotide polymorphisms (SNPs) within core promoters of 68 human rheumatoid arthritis (RA)-related genes. Using 603 SNPs within 25 genes clinically associated with RA-comorbid disorders, we predicted 84 and 70 candidate SNP markers for overexpression and underexpression of these genes, respectively, among which 58 and 96 candidate SNP markers, respectively, can relieve and worsen RA as if there is a neutral drift toward susceptibility to RA. Similarly, we predicted natural selection toward susceptibility to RA for 8 immunostimulatory genes (e.g., IL9R) and 10 genes most often associated with RA (e.g., NPY). On the contrary, using 25 immunosuppressive genes, we predicted 70 and 109 candidate SNP markers aggravating and relieving RA, respectively (e.g., IL1R2 and TGFB2), suggesting that natural selection can simultaneously additionally yield resistance to RA. We concluded that disruptive natural selection of human immunostimulatory and immunosuppressive genes is concurrently elevating and reducing the risk of RA, respectively. So, we hypothesize that RA in human could be a self-domestication syndrome referring to evolution patterns in domestic animals. We tested this hypothesis by means of public RNA-Seq data on 1740 differentially expressed genes (DEGs) of pets vs. wild animals (e.g., dogs vs. wolves). The number of DEGs in the domestic animals corresponding to worsened RA condition in humans was significantly larger than that in the related wild animals (10 vs. 3). Moreover, much less DEGs in the domestic animals were accordant to relieved RA condition in humans than those in the wild animals (1 vs. 8 genes). This indicates that the anthropogenic environment, in contrast to a natural one, affects gene expression across the whole genome (e.g., immunostimulatory and immunosuppressive genes) in a manner that likely contributes to RA. The difference in gene numbers is statistically significant as confirmed by binomial distribution (p < 0.01), Pearson's χ² (p < 0.01), and Fisher's exact test (p < 0.05). This allows us to propose RA as a candidate symptom within a self-domestication syndrome. Such syndrome might be considered as a human's payment with health for the benefits received during evolution.

Immunomodulatory Effects of Curcumin in Rheumatoid Arthritis: Evidence from Molecular Mechanisms to Clinical Outcomes

Rheumatoid arthritis (RA) is a chronic immune-mediated inflammatory disorder characterized by the destruction of the joint and bone resorption. The production of pro-inflammatory cytokines and chemokines, dysregulated functions of three important subtypes of T helper (T_H) cells including T_H1, T_H17, and regulator T (Treg) cells are major causes of the initiation and development of RA. Moreover, B cells as a source of the production of several autoantibodies play key roles in the pathogenesis of RA. The last decades have seen increasingly rapid advances in the field of immunopharmacology using natural origin compounds for the management of various inflammatory diseases. Curcumin, a main active polyphenol compound isolated from turmeric, curcuma longa, possesses a wide range of pharmacologic properties for the treatment of several diseases. This review comprehensively will assess beneficial immunomodulatory effects of curcumin on the production of pro-inflammatory cytokines and also dysregulated functions of immune cells including T_H1, T_H17, Treg, and B cells in RA. We also seek the clinical efficacy of curcumin for the treatment of RA in several recent clinical trials. In conclusion, curcumin has been found to ameliorate RA complications through modulating inflammatory and autoreactive responses in immune cells and synovial fibroblast cells via inhibiting the expression or function of pro-inflammatory mediators, such as nuclear factor-κB (NF-κB), activated protein-1 (AP-1), and mitogen-activated protein kinases (MAPKs). Of note, curcumin treatment without any adverse effects can attenuate the clinical symptoms of RA patients and, therefore, has therapeutic potential for the treatment of the diseases.

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.

Inhibitory activity of FOXP3+ regulatory T cells reveals high specificity for displaying immune tolerance in remission state rheumatoid arthritis

Immune regulation status may indicate immunological remission in rheumatoid arthritis (RA). This cross-sectional study aimed to determine the Regulatory T cell (Treg) properties, together with 14 plasma cytokines levels between active RA and clinical remission patients. Peripheral blood (PB) Foxp3+ Treg was collected from RA patients for determination of Treg inhibitory activity using a co-culture system. Other PB T cell types and plasma cytokines were determined by flow-cytometry. The Treg results were analyzed according to the disease activity score-28 (DAS28). Then sensitivity and specificity were calculated for the indication of the remission status. The number and inhibitory activity of Treg are higher in the clinical remission as compared to the active RA (p value < 0.0001). Also, Treg: CD4+CD25+CD127+ cell ratio demonstrates the similar result (p value < 0.05). Treg inhibitory activity is inversely correlated with the DAS28. Specificity and positive likelihood ratio of inhibitory activity for indicating remission status are 92.31% (95% CI 63.97-99.81) and 11.14 (95% CI 1.67-74.14), respectively. Treg inhibitory activity is a promising prognostic marker and probably represents the immunological remission status in RA.

Decipher manifestations and Treg /Th17 imbalance in multi-staging rheumatoid arthritis and correlation with TSDR/RORC methylation

T regulatory (Treg)/T-helper (Th) 17 imbalance has been shown to integrate with epigenetics to result in the development of autoimmune diseases. We aim to investigate the influence of disease staging on Treg/Th17 cells and whether the aberrant DNA methylation is implicated in the development of rheumatoid arthritis (RA). By recruiting 65 patients with multi-staging RA and 20 healthy controls (HC), we found that patients with active RA exhibited relative lymphopenia and higher WBC, neutrophils, and PLT. Circulating Treg/Th17 in patients with early active RA was significantly decreased. The expression of IL-6 and IL-17A was significantly increased in early active RA, whereas that of IL-10 and TGF-β was on the contrary. Furthermore, the frequency of Treg cells and Treg/Th17 were negatively correlated with DAS28, and the frequency of Th17 cells was on the contrary. Levels of DNA methylation related enzymes had significant difference between early active RA and HC. Relative hypermethylation was observed at the gene level for Treg-specific demethylated region (TSDR) and hypomethylation for retinoic acid-related orphan receptor (ROR)-C in early active RA. Thus, manifestations of RA and Treg/Th17 imbalance vary with disease staging, and the aberrant DNA methylation pattern may contribute to RA disease pathogenesis. Our results highlight the importance of disease staging in clinical research.

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.

Defining remission in rheumatoid arthritis: does it matter to the patient? A comparison of multi-dimensional remission criteria and patient reported outcomes

OBJECTIVES

In a cross-sectional study, we evaluated the prevalence of 'multi-dimensional remission' (MDR) and its component parameters, assessed using objective measures in a cohort of RA patients in treatment-induced DAS28-remission, and their relationship with patient-reported outcome measures. We sought to confirm the feasibility and face validity of the MDR construct, providing a platform for future longitudinal studies in which its clinical utility might be further established.

METHODS

605 patients were selected from an inflammatory arthritis register using DAS28(CRP)<2.6. Demographic, clinical and patients reported outcomes (PRO) data were collected. Ultrasound power doppler synovitis (n = 364) and T-cell subsets (n = 297) were also measured. Remission using clinical parameters was defined as: tender and swollen joint count (TJC/SJC) and CRP all ⩽1; ultrasound remission: total power doppler = 0 and T cell remission: positive normalized naïve T-cell frequency. MDR was defined as the achievement of all three dimensions.

RESULTS

Overall, only 53% (321/605) of the patients achieved clinical parameters, failures being mainly due to raised CRP (52%), TJC (28)>1 (37%) or SJC (28)>1 (16%). 211/364 (58%) of patients achieved ultrasound remission and 193/297 (65%) patients showed T-cell remission. Complete data were available for 231 patients. MDR was observed in only 35% and was associated with the best (lower) PRO scores (all P ⩽ 0.05 vs non-MDR) when compared with the other definitions of remission assessed. The MDR rate was similar in early and established RA patients on b-DMARDs; however, it was lower in established RA patients who received multiple cs-DMARDs (P = 0.011).

CONCLUSIONS

In this study, MDR, which may represent a state closer to normality, was found to occur in about a third of DAS28-remission patients and was associated with better patient-reported outcome measures. MDR could be a novel optimal treatment target, notably from a patient's perspective. The relevance of these findings needs further assessment.

The progress and prospect of regulatory T cells in autoimmune diseases

Regulatory T cells (Treg) are an important immune cell population, playing a crucial role in regulating immune tolerance and preventing autoimmune diseases. These cells consist of various cell sub-populations and generally have an immunoregulatory or suppressive role against immune responses. They also have a different cell heterogeneity and each populations has own biological characteristics. Treg deficiency, reduction, instability, reduced vitality and dysfunction all account for multiple autoimmune diseases. In this review, we have systemically reviewed Treg classification, phenotypic features, regulation of Foxp3 expression, plasticity and stability of Treg as well as their relationship with several important autoimmune diseases. We particularly focus on why and how inflammatory and diet environments affect the functional capacity and underlying mechanisms of Treg cell populations. We also summarize new advances in technologies which help to analyze and dissect these cells in molecular levels in-depth. We also clarify the possible clinical relevance on application of these cells in patients with autoimmune diseases. The advantages and weaknesses have been carefully discussed as well. We also propose the possible approaches to overcome these weaknesses of Treg cells in complicate environments. Thus, we have displayed the updated knowledge of Treg cells, which provides an overall insight into the role and mechanisms of Treg cells in autoimmune diseases.

Regulatory T cells in patients with early untreated rheumatoid arthritis: Phenotypic changes in the course of methotrexate treatment

Rheumatoid arthritis (RA) is frequent systemic autoimmune disease characterized by excessive activation of collagen-specific T helper cells, and elevated level of autoantibodies in the serum. Development of RA is associated with defect in compartment of regulatory CD4+Foxp3+ T cells (Treg), but data concerning suppressive potential of Treg population in RA patients are contradictory and depend on the stage of disease. In this study we aimed to characterize abundance and phenotypic markers of CD4+Foxp3+ Treg in peripheral blood of healthy donors compared to untreated early RA patients to find potential correlations with the disease activity, antibody level, and absolute numbers and proportion of different subpopulations of T cells. Moreover, we assessed the influence of methotrexate (MT) treatment on percentage and absolute numbers of CD4+Foxp3+ Treg from the peripheral blood of untreated early RA patients. We demonstrate that increase and phenotypic changes in Treg population correlate well with response to MT. Analysis of the cohorts of matched RA patients (n = 45) and healthy controls (n = 20) revealed that patients with untreated early RA demonstrate substantial decrease in blood Treg percentage and absolute number, as well as low level of activated Treg surface markers in comparison to healthy control. The defect in Treg compartment negatively correlates with both RA activity and antibody level. MT treatment of patients with early untreated RA increases both proportion and absolute number of Treg with high level of activation markers, suggesting an increase of their functional capacity. Here we speculate the role of Tregs as specific cellular marker of successful RA treatment.

T-cell subset abnormalities predict progression along the Inflammatory Arthritis disease continuum: implications for management

The presence of a disease continuum in inflammatory arthritis (IA) is a recognised concept, with distinct stages from at-risk stage (presence of anti citrullinated-peptide autoantibody) to diagnosis of rheumatoid arthritis (RA), including therapy-induced remission. Despite T-cell dysregulation being a key feature of RA, there are few reports of T-cell phenotyping along the IA-continuum. We investigated the disturbances of naïve, regulatory and inflammation related cell (IRC) CD4+ T-cell subsets in 705 individuals across the IA-continuum, developing a simple risk-score (summing presence/absence of a risk-associated with a subset) to predict progression from one stage to the next. In 158 at-risk individuals, the 3 subsets had individual association with progression to IA and the risk-score was highly predictive (p < 0.0001). In evolving IA patients, 219/294 developed RA; the risk-score included naïve and/or Treg and predicted progression (p < 0.0001). In 120 untreated RA patients, the risk-score for predicting treatment-induced remission using naïve T-cells had an odds ratio of 15.4 (p < 0.0001). In RA patients in treatment-induced remission, a score using naïve T-cells predicted disease flare (p < 0.0001). Evaluating the risk of progression using naïve CD4+ T-cells was predictive of progression along the whole IA-continuum. This should allow identification of individuals at high-risk of progression, permitting targeted therapy for improved outcomes.

MicroRNA-125b regulates Th17/Treg cell differentiation and is associated with juvenile idiopathic arthritis

BACKGROUND

Juvenile idiopathic arthritis (JIA) is the most common rheumatic disease in childhood driven by aberrant pathways of T-cell activation. T helper 17 (Th17)/regulatory T cell (Treg) imbalance plays critical roles in the pathogenesis of arthritis. MicroRNA-125b (miR-125b) was upregulated after the activation of the initial CD4⁺ T cells, and could regulate the differentiation of CD4⁺ T cells. However, the effects of miR-125b on Th17/Treg imbalance and differentiation of Th17/Treg cells remain unknown.

METHODS

In this study, we evaluated the expression of miR-125b in the peripheral blood mononuclear cells (PBMCs) of children with JIA, and the relationship of miR-125b with Th17/Treg imbalance. Then, we used lentivirus vector-mediated overexpression technology to investigate the regulatory function of miR-125b in CD4⁺ T cells or dendritic cell/CD4⁺ T co-culture system.

RESULTS

Decreased miR-125b expression in PBMCs and CD4⁺ T cells of JIA patients was negatively correlated with the ratio of Th17/Treg cells. It also correlated negatively with retinoic acid receptor-related orphan receptor γt but positively with Forkhead box protein 3 at transcriptional levels. Furthermore, we found that miR-125b overexpression inhibited Th17 cell differentiation, whereas facilitated the differentiation of Treg cells. MiR-125b upregulation led to the decrease of Th17-secreting cytokines but the increase of the Treg-secreting cytokines.

CONCLUSIONS

Our results demonstrate that miR-125b participated in regulating Th17/Treg cell differentiation and imbalance in JIA patients. These findings provide novel insight into the critical role of miR-125b in the Th17/Treg imbalance of JIA, and raise the distinct possibility that miR-125b may prove to be a potential therapeutic target for JIA.

Matured Tolerogenic Dendritic Cells Effectively Inhibit Autoantigen Specific CD4+ T Cells in a Murine Arthritis Model

Tolerogenic dendritic cells (tolDCs) are a promising treatment modality for diseases caused by a breach in immune tolerance, such as rheumatoid arthritis. Current medication for these diseases is directed toward symptom suppression but no real cure is available yet. TolDC-based therapy aims to restore immune tolerance in an antigen-specific manner. Here we used a mouse model to address two major questions: (i) is a maturation stimulus needed for tolDC function in vitro and in vivo and is maturation required for functioning in experimental arthritis and (ii) can tolDCs modulate CD4⁺ T cell responses? To answer these questions, we compared matured and immature dexamethasone/vitamin D3-generated tolDCs in vitro. Subsequently, we co-transferred these tolDCs with naïve or effector CD4⁺ T cells to study the characteristics of transferred T cells after 3 days with flow cytometry and Luminex multiplex assays. In addition, we tested the suppressive capabilities of tolDCs in an experimental arthritis model. We found that tolDCs cannot only modulate naïve CD4⁺ T cell responses as shown by fewer proliferated and activated CD4⁺ T cells in vivo, but also effector CD4⁺ T cells. In addition, Treg (CD4⁺CD25⁺FoxP3⁺) expansions were seen in the proliferating cell population in the presence of tolDCs. Furthermore, we show that administered tolDCs are capable to inhibit arthritis in the proteoglycan-induced arthritis model. However, a maturation stimulus is needed for tolDCs to manifest this tolerizing function in an inflammatory environment. Our data will be instrumental for optimization of future tolDC therapies for autoimmune diseases.

IL-6 Mediated Transcriptional Programming of Naïve CD4+ T Cells in Early Rheumatoid Arthritis Drives Dysregulated Effector Function

Objective: We have previously shown that increased circulating interleukin-6 (IL-6) results in enhanced CD4+ T cell signaling via signal transduction and activator of transcription-3 (STAT3) in early rheumatoid arthritis (RA). We tested the hypothesis that transcriptional “imprinting” of T-cells by this mechanism skews downstream effector responses, reinforcing immune dysregulation at a critical, but targetable, disease phase.

Methods: We modeled naïve CD4+ T cell exposure to pathophysiological concentrations of IL-6 in vitro, assessing the dynamic transcriptional and functional consequences for downstream effector cells utilizing microarray and flow cytometry. Fresh blood from treatment-naïve early arthritis patients was phenotyped in parallel for comparison.

Results: T cell sensitivity to IL-6 was most marked in the naïve subset, and related to gp130 rather than IL-6R expression. Exposure of healthy naïve CD4+ T cells to IL-6 induced the same STAT3 target genes as previously seen to discriminate RA patients from disease controls. After TCR stimulation IL-6 pre-exposed cells exhibited enhanced proliferative capacity, activation, and a propensity toward Th1 differentiation, compared to non-exposed cells. An entirely analogous phenotype was observed in early RA compared to control CD4+ T cells.

Conclusions: Sustained IL-6 exposure at a critical point in the natural history of RA “primes” the adaptive immune system to respond aberrantly to TCR stimulation, potentiating disease induction with implications for the optimal timing of targeted therapy.

Helios but not CD226, TIGIT and Foxp3 is a Potential Marker for CD4+ Treg Cells in Patients with Rheumatoid Arthritis

BACKGROUND/AIMS

Rheumatoid arthritis (RA) is a progressive, chronic, even disabling systemic autoimmune disease. Imbalance between pathogenic immune cells and immunosuppressive cells is associated with the pathogenesis and development of RA and other autoimmune diseases. As Foxp3 is also expressed on activated CD4⁺ cells in the presence of inflammation, the identification of Treg cells in patients with RA remains a challenge.

METHODS

Comprehensive analyses were carried out by Flow cytometry. Expression of Helios, CD226, T cell immunoreceptor with Ig and ITIM domains clinical samples and healthy controls.

RESULTS

We have systemically examined three potential markers, Helios, CD226 and TIGIT, that are possibly related to Treg identification, and found that Helios expression on CD4⁺Foxp3⁺cells was decreased and negatively correlated with the disease activity of RA patients, while CD226 and TIGIT both showed elevated expression levels in CD4⁺Foxp3⁺cells in RA patients and they were not associated with disease activity of RA patients.

CONCLUSION

Taken together, our findings indicate that CD4⁺CD25^hiCD127^low/-Foxp3⁺Helios⁺ may represent the real Treg cell population in patients with RA.

The Pivotal Role of Regulatory T Cells in the Regulation of Innate Immune Cells

The distinction between innate and adaptive immunity is one of the basic tenets of immunology. The co-operation between these two arms of the immune system is a major determinant of the resistance or susceptibility of the host following pathogen invasion. Hence, this interactive co-operation between cells of the innate and adaptive immunity is of significant interest to immunologists. The sub-population of CD4⁺ T cells with regulatory phenotype (regulatory T cells; Tregs), which constitute a part of the adaptive immune system, have been widely implicated in the regulation of the immune system and maintenance of immune homeostasis. In the last two decades, there has been an explosion in research describing the role of Tregs and their relevance in several immunopathologies ranging from inflammation to cancer. The majority of these studies focus on the role of Tregs on the cells of the adaptive immune system. Recently, there is significant interest in the role of Tregs on cells of the innate immune system. In this review, we examine the literature on the role of Tregs in immunology. Specifically, we focus on the emerging knowledge of Treg interaction with dendritic cells, macrophages, neutrophils, and γδ T cells. We highlight this interaction as an important link between innate and adaptive immune systems which also indicate the far-reaching role of Tregs in the regulation of immune responses and maintenance of self-tolerance and immune homeostasis.

Mechanisms of human FoxP3+ Treg cell development and function in health and disease

Regulatory T (T_reg) cells represent an essential component of peripheral tolerance. Given their potently immunosuppressive functions that is orchestrated by the lineage‐defining transcription factor forkhead box protein 3 (FoxP3), clinical modulation of these cells in autoimmunity and cancer is a promising therapeutic target. However, recent evidence in mice and humans indicates that T_reg cells represent a phenotypically and functionally heterogeneic population. Indeed, both suppressive and non‐suppressive T_reg cells exist in human blood that are otherwise indistinguishable from one another using classical T_reg cell markers such as CD25 and FoxP3. Moreover, murine T_reg cells display a degree of plasticity through which they acquire the trafficking pathways needed to home to tissues containing target effector T (T_eff) cells. However, this plasticity can also result in T_reg cell lineage instability and acquisition of proinflammatory T_eff cell functions. Consequently, these dysfunctional CD4⁺FoxP3⁺ T cells in human and mouse may fail to maintain peripheral tolerance and instead support immunopathology. The mechanisms driving human T_reg cell dysfunction are largely undefined, and obscured by the scarcity of reliable immunophenotypical markers and the disregard paid to T_reg cell antigen‐specificity in functional assays. Here, we review the mechanisms controlling the stability of the FoxP3⁺ T_reg cell lineage phenotype. Particular attention will be paid to the developmental and functional heterogeneity of human T_reg cells, and how abrogating these mechanisms can lead to lineage instability and T_reg cell dysfunction in diseases like immunodysregulation polyendocrinopathy enteropathy X‐linked (IPEX) syndrome, type 1 diabetes, rheumatoid arthritis and cancer.

Context-Dependent Effect of Glucocorticoids on the Proliferation, Differentiation, and Apoptosis of Regulatory T Cells: A Review of the Empirical Evidence and Clinical Applications

Glucocorticoids (GCs) are widely used to treat several diseases because of their powerful anti-inflammatory and immunomodulatory effects on immune cells and non-lymphoid tissues. The effects of GCs on T cells are the most relevant in this regard. In this review, we analyze how GCs modulate the survival, maturation, and differentiation of regulatory T (Treg) cell subsets into both murine models and humans. In this way, GCs change the Treg cell number with an impact on the mid-term and long-term efficacy of GC treatment. In vitro studies suggest that the GC-dependent expansion of Treg cells is relevant when they are activated. In agreement with this observation, the GC treatment of patients with established autoimmune, allergic, or (auto)inflammatory diseases causes an expansion of Treg cells. An exception to this appears to be the local GC treatment of psoriatic lesions. Moreover, the effects on Treg number in patients with multiple sclerosis are uncertain. The effects of GCs on Treg cell number in healthy/diseased subjects treated with or exposed to allergens/antigens appear to be context-dependent. Considering the relevance of this effect in the maturation of the immune system (tolerogenic response to antigens), the success of vaccination (including desensitization), and the tolerance to xenografts, the findings must be considered when planning GC treatment.

Tolerising cellular therapies: what is their promise for autoimmune disease?

The current management of autoimmunity involves the administration of immunosuppressive drugs coupled to symptomatic and functional interventions such as anti-inflammatory therapies and hormone replacement. Given the chronic nature of autoimmunity, however, the ideal therapeutic strategy would be to reinduce self-tolerance before significant tissue damage has accrued. Defects in, or defective regulation of, key immune cells such as regulatory T cells have been documented in several types of human autoimmunity. Consequently, it has been suggested that the administration of ex vivo generated, tolerogenic immune cell populations could provide a tractable therapeutic strategy. Several potentially tolerogenic cellular therapies have been developed in recent years; concurrent advances in cell manufacturing technologies promise scalable, affordable interventions if safety and efficacy can be demonstrated. These therapies include mesenchymal stromal cells, tolerogenic dendritic cells and regulatory T cells. Each has advantages and disadvantages, particularly in terms of the requirement for a bespoke versus an ‘off-the-shelf’ treatment but also their suitability in particular clinical scenarios. In this review, we examine the current evidence for these three types of cellular therapy, in the context of a broader discussion around potential development pathway(s) and their likely future role. A brief overview of preclinical data is followed by a comprehensive discussion of human data.

Serum levels of proinflammatory, anti-inflammatory cytokines, and RANKL/OPG in synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome

OBJECTIVE

To measure the expression of proinflammatory, anti-inflammatory cytokines, and receptor activator NK-κB ligand (RANKL)/osteoprotegerin (OPG) in synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome, and to assess the relationship between those factors and disease activity.

METHODS

We studied 30 cases of SAPHO syndrome and 15 healthy controls. According to the Visual Analogue Scale (VAS) pain scores and Bath Ankylosing Spondylitis Activity Index (BASDAI), patients were divided into active group and stable group. The serum levels of IFN-γ, TNF-α, TGF-β1, IL-1β, IL-4, IL-6, IL-8, IL-17A, IL-22, RANKL, and OPG were determined by ELISA.

RESULTS

The active group IL-6 (2.34 ± 1.31 pg/ml), IL-8 (36.41 ± 12.93 pg/ml), and IL-17A (29.17 ± 4.01 pg/ml) levels were significantly higher than those in the stable group (p < .01) and healthy controls (p < .01). RANKL in active group (73.43 ± 57.07 pg/ml) was significantly higher than the ones in other groups (p < .0001), with increased RANKL/OPG ratio in the active group compared with other groups (p < .05). While the level of TGF-β1 in the active group was significantly lower than that in the stable and control groups (p < .0001). There was no significant difference with clinical significance were found in IFN-γ, TNF-α, IL-1β, IL-4, IL-22, and OPG.

CONCLUSION

In active SAPHO patients, there was an anomaly of proinflammatory and anti-inflammatory cytokines balance in SAPHO syndrome.

High Interleukin-37 (IL-37) Expression and Increased Mucin-Domain Containing-3 (TIM-3) on Peripheral T Cells in Patients with Rheumatoid Arthritis

Background

Anti-inflammatory mediators such as mucin-domain containing-3 (TIM-3) and IL-37 play an important role in the regulation of Th1-mediated immunity. This study was designed to investigate the proportions of various T cell subsets and monocytes in the peripheral blood of rheumatoid arthritis (RA) patients, as well as the level of TIM-3 on these cells and serum cytokine levels.

Material/Methods

We enrolled 59 RA patients and 46 age- and sex-matched healthy controls in this study. The proportion of T cells and TIM-3 expression on these T cells were determined by flow cytometry. Cytokine levels in serum were determined by ELISA.

Results

Compared with the healthy controls, the proportions of CD3⁺CD4⁺ T cells and CD3⁺CD4⁺CD25⁺CD127^low T cells in the peripheral blood were significantly higher in RA patients. However, RA patients had significantly lower proportions of CD3⁺CD8⁺ T cells and CD3⁺CD4⁻CD8⁻ T cells. TIM-3 was highly expressed on CD3⁺CD4⁺, CD3⁺CD8⁺, CD3⁺CD4⁺CD25⁺CD127^low, and CD3⁺CD4⁻CD8⁻ T cells, as well as CD14⁺ monocytes, in RA patients. Nevertheless, no correlation between TIM-3 level and an RA disease activity score of 28 was found. The elevated serum levels of IL-6 and IL-37 were positively correlated with tumor necrosis factor-α (TNF-α).

Conclusions

Both pro-inflammatory cytokines (TNF-α and IL-6) and anti-inflammatory mediators (TIM-3 and IL-37) simultaneously contribute to the pathogenesis of RA. TIM-3 and IL-37 may be used as potential biomarkers of active RA.

Lymphocytes as Biomarkers of Therapeutic Response in Rheumatic Autoimmune Diseases, Is It a Realistic Goal?

Many therapies are available for patients with rheumatoid arthritis (RA) while biological therapies have limited effects in patients with systemic lupus erythematosus (SLE) and primary Sjögren's syndrome (pSS). In both cases, biomarkers predicting drug response would be very useful to guide clinicians in their choice. We performed a systematic review to evaluate the value of lymphocyte phenotyping as a marker of therapeutic response. Of the 1063 articles retrieved, 39 fulfilled inclusion criteria and were included in the present review (25 for RA, 10 for SLE, and 4 for pSS). Lymphocyte phenotyping was described as a biomarker of therapeutic response in many studies, but most results could not be confirmed by independent teams using multivariate analysis. The most consistent result might be the association between rituximab response and the levels of memory B cells before therapy, although some studies were controversial. Thus, lymphocyte phenotyping cannot yet be proposed as a biomarker of response in rheumatic autoimmune diseases. The lack of reproducibility between studies may be explained by technical issues influencing lymphocyte phenotyping so standardization procedures should be developed for future studies. The patients' characteristics vary between studies, and large population studies, including a wide range of patients' characteristics and biomarkers, are required to provide predictive models for clinical outcomes. The use of new flow cytometry techniques such as single-cell mass cytometry technology might also help finder reliable biomarkers in the future.

Could Lymphocyte Profiling be Useful to Diagnose Systemic Autoimmune Diseases?

Considering the implications of B, T, and natural killer (NK) cells in the pathophysiology of systemic autoimmune diseases, the assessment of their distribution in the blood could be helpful for physicians in the complex process of determining a precise diagnosis. In primary Sjögren's syndrome, transitional and active naive B cells are increased and memory B cells are decreased compared to healthy controls and other systemic diseases. However, their utility to improve the accuracy of classification criteria has not been proven. In early untreated rheumatoid arthritis, proportions of regulatory T cells are constantly reduced, but other patterns are difficult to determine given the heterogeneity of published studies. In systemic lupus erythematosus, the lack of studies using large cohorts of patients and the diversity of the possible pathological mechanisms involved are also important impediments. Nevertheless, transitional B cell and plasma cell proportions are increased in most of the studies, the CD4/CD8 ratio is decreased, and the number of NK cells is reduced. Despite the low number of studies, anomalies of lymphocyte subset distribution was also described in ANCA-associated vasculitis, systemic scleroderma, and myositis. For now, flow cytometric analysis of lymphocyte subsets has focused mainly on specific subpopulations and is more useful for basic and translational research than for diagnostics in clinical practice. However, new modern methods such as mass cytometry and bioinformatics analyses may offer the possibility to simultaneously account for the relative proportions of multiple lymphocyte subsets and define a global profile in homogeneous groups of patients. The years to come will certainly incorporate such global lymphocyte profiling in reclassification of systemic autoimmune diseases.

Peripheral CD4+ T-cell changes in connective tissue diseases

Connective tissue diseases (CTDs) are all characterized by changes in the adaptive immune system. In the last few decades several CD4 + T lymphocytes and their products have been associated with the development, progression, organ involvement, or therapeutic response of different CTDs. The T helper (Th) T-cell subsets are easy to measure in the peripheral blood, however changes are difficult to interpret. This review summarizes data about Th1/Th2/Th17 and regulatory T-cell (Treg) changes in the most common CTDs. Concordance and divergence of data might help in the better understanding of the common processes of these different systemic autoimmune disorders and might give future clues for differences in disease behavior and treatment response.

Clinical Applications of Regulatory T cells in Adoptive Cell Therapies

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

Leveraging blood and tissue CD4+ T cell heterogeneity at the single cell level to identify mechanisms of disease in rheumatoid arthritis

CD4+ T cells have been long known to play an important role in the pathogenesis of rheumatoid arthritis (RA), but the specific cell populations and states that drive the disease have been challenging to identify with low dimensional single cell data and bulk assays. The advent of high dimensional single cell technologies-like single cell RNA-seq or mass cytometry-has offered promise to defining key populations, but brings new methodological and statistical challenges. Recent single cell profiling studies have revealed a broad diversity of cell types among CD4+ T cells, identifying novel populations that are expanded or altered in RA. Here, we will review recent findings on CD4+ T cell heterogeneity and RA that have come from single cell profiling studies and discuss the best practices for conducting these studies.

The Yin and Yang of regulatory T cell and therapy progress in autoimmune disease

Autoimmune diseases (ADs) are primarily mediated by the failure of immunological self-tolerance. Regulatory T cells (Tregs) play a critical role in the maintenance of induced tolerance to peripheral self-antigens, suppressing immoderate immune responses deleterious to the host and preventing the AD development. Tregs and suppressive cytokines are homeostatic with effective cells plus pro-inflammatory cytokines in healthy hosts which is defined as "Yang", and ADs are usually induced in case of disturbed homeostasis, which is defined as "Yin". Indeed, the Yin-Yang balance could explain the pathogenic mechanism of ADs. Tregs not only suppress CD4⁺ and CD8⁺ T cells but also can suppress other immune cells such as B cell, natural killer cell, DC and other antigen-presenting cell through cell-cell contact or secreting suppressive cytokines. In Tregs, Foxp3 as an intracellular protein displays a more specific marker than currently used other cell-surface markers (such as CD25, CD40L, CTLA-4, ICOS and GITR) in defining the naturally occurring CD4⁺ Tregs. Though the precise mechanism for the opposite effects of Tregs has not been fully elucidated, the importance of Tregs in ADs has been proved to be associated with kinds of immunocytes. At present, the surface marker, frequency and function of Tregs existed conflicts and hence the Tregs therapy in ADs faces challenges. Though some success has been achieved with Tregs therapy in few ADs both in murine models and humans, more effort should paid to meet the future challenges. This review summarizes the progress and discusses the phenotypic, numeric and functional abnormalities of Tregs and is the first time to systematically review the progress of Tregs therapy in kinds of ADs.

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.

Regulatory T Cell and Forkhead Box Protein 3 as Modulators of Immune Homeostasis

The transcription factor forkhead box protein 3 (FOXP3) is an essential molecular marker of regulatory T cell (Treg) development in different microenvironments. Tregs are cells specialized in the suppression of inadequate immune responses and the maintenance of homeostatic tolerance. Studies have addressed and elucidated the role played by FOXP3 and Treg in countless autoimmune and infectious diseases as well as in more specific cases, such as cancer. Within this context, the present article reviews aspects of the immunoregulatory profile of FOXP3 and Treg in the management of immune homeostasis, including issues relating to pathology as well as immune tolerance.

Novel Senescent Regulatory T-Cell Subset with Impaired Suppressive Function in Rheumatoid Arthritis

Objective

Premature senescence of lymphocytes is a hallmark of inflammatory rheumatic diseases such as rheumatoid arthritis (RA). Early T-cell aging affects conventional T-cells but is presumably not limited to this cell population; rather it might also occur in the regulatory T-cells (Tregs) compartment. In RA, Tregs fail to halt aberrant immune reactions and disease progression. Whether this is associated with early Treg senescence leading to phenotypic and functional changes of this subset is elusive so far.

Methods

Eighty-four RA patients and 75 healthy controls were prospectively enrolled into the study. Flow cytometry, magnetic-associated cell sorting, and cell culture experiments were performed for phenotypic and functional analyses of Treg subsets. T-cell receptor excision circle (TREC) levels and telomere lengths were determined using RT-PCR.

Results

In this paper, we describe the novel CD4⁺FoxP3⁺CD28⁻ T-cell subset (CD28⁻ Treg-like cells) in RA patients revealing features of both Tregs and senescent T-cells: Treg surface/intracellular markers such as CD25, CTLA-4, and PD-1 as well as FOXP3 were all expressed by CD28⁻ Treg-like cells, and they yielded signs of premature senescence including reduced TREC levels and an accumulation of γH2AX. CD28⁻ Treg-like could be generated in vitro by stimulation of (CD28⁺) Tregs with TNF-α. CD28⁻ Treg-like cells insufficiently suppressed the proliferation of effector T-cells and yielded a pro-inflammatory cytokine profile.

Conclusion

In conclusion, we describe a novel T-cell subset with features of Tregs and senescent non-Tregs. These cells may be linked to an aberrant balance between regulatory and effector functions in RA.

Th17 and CD24hiCD27+ regulatory B lymphocytes are biomarkers of response to biologics in rheumatoid arthritis

Background

The aim was to describe the regulatory B and T cells (Breg and Treg) and T helper 17 (Th17) lymphocytes before and under treatment with biologic drugs, and to assess their potential predictive value as biomarkers of response in rheumatoid arthritis (RA).

Methods

This was a non-randomised, single-centre, prospective study. Patients with active RA (American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) 2010) who required the initiation or switch to any biologic drug except rituximab were included. The main judgement criterion was the frequency and absolute number of CD24^hiCD27⁺ Breg and CD24^hiCD38^hi T2/Breg cells, CD25^hiCD127^low Treg and CD45RA⁻CD161⁺CCR6⁺ Th17 cells measured at inclusion in both patients and controls, and after 1, 3 and 6 months of treatment (M1, M3 and M6) in patients with RA, and compared with the M6 response to treatment (EULAR response and Disease Activity Score in 28 joints (DAS28) remission).

Results

Thirty-one patients with RA and 17 controls were included. There was a reduction in T2/Breg frequency at M0 in patients (p < 0.001) and absolute numbers (p = 0.014) and in immunopositive vs. immunonegative RA (p = 0.016). DAS28 remission at M6 was associated with increased frequency of Treg (p = 0.01). A higher level of CD24^hiCD27⁺ Breg at baseline was associated with DAS28 remission at M6 (p = 0.04) and a good EULAR response at M6 for abatacept-treated patients (p = 0.01). A lower M0 level of Th17 was associated with a good EULAR response at M6 (p = 0.007), notably under anti-cytokine drugs (p = 0.048).

Conclusions

Altogether, these data, although preliminary, suggest that phenotyping of T and B cells has potential value for the stratification of biologic drugs, notably with respect to choosing between abatacept and anti-cytokine blockade.