Quantification of regulatory T cells in peripheral blood of patients with systemic lupus erythematosus

Distinct Localization, Transcriptional Profiles, and Functionality in Early Life Tonsil Regulatory T Cells

CD4+ regulatory T cells (Tregs) are key orchestrators of the immune system, fostering the establishment of protective immunity while preventing deleterious responses. Infancy and childhood are crucial periods of rapid immunologic development, but how Tregs mediate immune responses at these earliest timepoints of human life is poorly understood. In this study, we compare blood and tissue (tonsil) Tregs across pediatric and adult subjects to investigate age-related differences in Treg biology. We observed increased FOXP3 expression and proportions of Tregs in tonsil compared with paired blood samples in children. Within tonsil, early life Tregs accumulated in extrafollicular regions with cellular interactions biased toward CD8+ T cells. Tonsil Tregs in both children and adults expressed transcriptional profiles enriched for lineage defining signatures and canonical functionality compared with blood, suggesting tissue as the primary site of Treg activity. Early life tonsil Tregs transcriptional profiles were further defined by pathways associated with activation, proliferation, and polyfunctionality. Observed differences in pediatric tonsil Treg transcriptional signatures were associated with phenotypic differences, high proliferative capacity, and robust production of IL-10 compared with adult Tregs. These results identify tissue as a major driver of Treg identity, provide new insights into developmental differences in Treg biology across the human lifespan, and demonstrate unique functional properties of early life Tregs.

Potential effects of shift work on skin autoimmune diseases

Shift work is associated with systemic chronic inflammation, impaired host and tumor defense and dysregulated immune responses to harmless antigens such as allergens or auto-antigens. Thus, shift workers are at higher risk to develop a systemic autoimmune disease and circadian disruption with sleep impairment seem to be the key underlying mechanisms. Presumably, disturbances of the sleep-wake cycle also drive skin-specific autoimmune diseases, but epidemiological and experimental evidence so far is scarce. This review summarizes the effects of shift work, circadian misalignment, poor sleep, and the effect of potential hormonal mediators such as stress mediators or melatonin on skin barrier functions and on innate and adaptive skin immunity. Human studies as well as animal models were considered. We will also address advantages and potential pitfalls in animal models of shift work, and possible confounders that could drive skin autoimmune diseases in shift workers such as adverse lifestyle habits and psychosocial influences. Finally, we will outline feasible countermeasures that may reduce the risk of systemic and skin autoimmunity in shift workers, as well as treatment options and highlight outstanding questions that should be addressed in future studies.

CXCR3 antagonist AMG487 inhibits glucocorticoid-induced tumor necrosis factor-receptor-related protein and inflammatory mediators in CD45 expressing cells in collagen-induced arthritis mouse model

Rheumatoid arthritis (RA) is an autoimmune disease classified by uncontrolled joint inflammation leading to the destruction of both cartilage and joints. Despite progress made in RA treatment in the past decade, new drugs with high efficacy and fewer long-term adverse effects are still needed; thus, safe anti-inflammatory therapies for RA are urgently needed. Previous results demonstrated that the CXCR3 antagonist is an extremely attractive therapeutic target for the treatment of several autoimmune diseases, suggesting that it might have an inhibitory effect on RA. In this study, we investigated the effect of AMG487, a selective CXCR3 antagonist, on collagen-induced arthritis (CIA) in mice and evaluated its potential therapeutic mechanism.Following induction of CIA, mice were treated with AMG487 (5 mg/kg, intraperitoneally), to investigate their protective effects against CIA. CD4, CD25, CCR6, IL-9, NF-κB, IL-6, IL-17A, IL-21, STAT6 and Foxp3 expressing GITR⁺ and CD45⁺ cells were measured in the spleen using flow cytometry to assess anti-inflammatory effects of AMG487. The mRNA and protein expression of GITR, CCR6, IL-9, and IL-21 were measured using quantitative real-time PCR and western blot analysis in knee tissue. AMG487 significantly alleviated joint inflammation by decreasing GITR⁺CD25⁺, GITR⁺CD45⁺, GITR⁺IL-9⁺, GITR⁺NF-κB⁺ CD45⁺CD4⁺, CD45⁺CCR6⁺, CD45⁺IL-6⁺ cells, CD45⁺IL-17A⁺, and CD45⁺IL-21⁺, and increasing GITR⁺Foxp3⁺ and GITR⁺STAT6⁺ cells. There was a significant decrease in mRNA and protein expression of GITR, CD4, CCR6, IL-6, IL-9, and IL-21 in knee tissue of CIA mice. This study demonstrates that AMG487 has a potential therapeutic effect on RA and could explore novel anti-inflammatory therapies for its treatment.

CD8+CD103+ iTregs inhibit the progression of lupus nephritis by attenuating glomerular endothelial cell injury

OBJECTIVES

We previously reported that ex vivo TGF-β and IL-2-induced CD8+CD103+ regulatory T cells (CD8+CD103+ iTregs) displayed similar immunosuppressive effect and therapeutic function on lupus mice nephritis to that of CD4+Foxp3+ Tregs. In view of the important role of glomerular endothelial cell (GEC) injury in inflammatory processes in SLE, this study aimed to investigate the nature and mechanism of CD8+CD103+ iTregs-mediated amelioration of LN by attenuating GEC injury.

METHODS

Treg cells from patients with SLE and from healthy controls were characterized by flow cytometry analysis. The expression of pro-inflammatory mediators and VEGF were analysed in healthy controls, patients with SLE and MRL/lpr mice by ELISA, western blot, and real-time quantitative RT-PCR (qRT-PCR). Typical lesions of diffuse proliferative LN were observed in MRL/lpr mice through the use of haematoxylin and eosin, Masson, periodic acid-Schiff, periodic acid-Schiff methenamine, transmission electron microscopy and IF microscopy. Angiogenesis was analysed in GECs by cell investigating proliferation, migration, and tube formation.

RESULTS

The results revealed that the frequency of Treg cells was inversely correlated with the expression of VCAM-1 and ICAM-1 in patients with SLE. Furthermore, adoptive transfer of CD8+CD103+ iTregs to MRL/lpr mice was associated with decreased levels of autoantibodies and proteinuria, reduced renal pathological lesions, and lowered renal deposition of IgG/C3. We further found that CD8+CD103+ iTregs not only suppressed the expression of pro-inflammatory mediators but also attenuated GEC injury by promoting angiogenesis.

CONCLUSION

Our study has identified the role of CD8+CD103+ iTregs on attenuating GEC injury and provided a possible application of this new iTregs subset in lupus nephritis and other autoimmune diseases.

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 Regulatory T Cell in Active Systemic Lupus Erythematosus Patients: A Systemic Review and Meta-Analysis

Background: Regulatory T cells (Tregs) researches in systemic lupus erythematosus (SLE) have floundered over the years, reports on the numbers and function of Tregs in SLE present quite contradictory results. We therefore conducted a meta-analysis to verify the changes of Tregs in active SLE.

Methods: We systematically searched PubMed, Embase, and ISI web of knowledge databases for eligible articles. In total, 628 active SLE patients and 601 controls from 18 studies were included. Due to a high degree of heterogeneity, a random effects model was used to assess the mean differences in Treg percentages, absolute numbers, and suppression capacities of Tregs between active SLE and controls. Further, subgroup analysis was performed to identify potential sources of heterogeneity.

Results: The pooled percentages of Tregs in active SLE patients were found to be lower than those in controls (−0.864 ± 0.308, p = 0.005), with great heterogeneity (I² = 95.01). The discrepancy of published results might result from the following differences among studies: gating strategies for Tregs, diagnostic criteria for SLE, and thresholds of SLEDAI chosen to differentiate between active and inactive SLE. In active SLE, Tregs gated based on CD25 alone showed lower pooled frequency than those gated by Foxp3⁺ or CD127^low/∅. The percentages of Tregs in active SLE was significantly lower than that in controls when the enrolled SLE patients were diagnosed according to the 1997 modified criteria, whereas they were comparable to controls when diagnosed by the 1982 criteria; the higher threshold of SLEDAI score used to define active SLE tended to achieve a lower percentage of Tregs. The pooled absolute numbers of Tregs in active SLE were significantly decreased compared to those in controls (−1.328 ± 0.374, p < 0.001), but seemed to be unaffected by gating strategies. Suppression capacities of Tregs from active SLE patients showed no abnormalities based on the limited pooled data. Longitudinal monitoring of active SLE showed a significant decrease in Treg percentage at remission.

Conclusions: This study implies that loss of Tregs may play a role in the pathogenesis of active SLE and help clarify contradictory Treg results in SLE.

Regulatory T-cell levels in systemic lupus erythematosus patients: a meta-analysis

Background

The contribution of regulatory T-cells (Tregs) to systemic lupus erythematosus (SLE) pathogenesis remains a matter of debate. The objective of this study was to quantify the association between peripheral blood Tregs and disease status in SLE patients.

Method

EMBASE and PubMed databases were searched using ‘systemic lupus erythematosus’ and ‘regulatory T-cells’ as relevant key terms. A meta-analysis of studies that examined the proportion of Tregs among peripheral blood mononuclear cells (PBMCs) and CD4+T-cells was performed using Stata software. Subgroup analysis was performed based on ethnic groups and Treg definition markers.

Results

The Treg/PBMC and Treg/CD4+T-cell ratios were significantly lower in SLE patients than in healthy controls (HCs), whereas patients with active and inactive SLE showed no difference in these indicators. A subgroup analysis indicated that Asian SLE patients had a substantially lower proportion of Tregs/PBMCs than HCs, but this difference was not seen for white and Latin American SLE patients. Patients defined by CD4+CD25+Foxp3+, CD4+CD25+ and CD4+Foxp3+ had a much lower Treg/PBMC ratio compared with HCs. Ethnic groups and choice of Treg definition markers had no influence on the proportion of Tregs/CD4+T-cells.

Conclusion

The proportion of Tregs among both PBMCs and CD4+T-cells was significantly decreased in SLE patients. Ethnic group and Treg definition markers may influence the proportion of Tregs among PBMCs. Further study of the correlation between SLE disease activity and the proportion of Tregs in peripheral blood is needed to determine the physiological role of this association.

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.

Protein losing enteropathy: comprehensive review of the mechanistic association with clinical and subclinical disease states

Protein losing enteropathy (PLE) has been associated with more than 60 different conditions, including nearly all gastrointestinal diseases (Crohn’s disease, celiac, Whipple’s, intestinal infections, and so on) and a large number of non-gut conditions (cardiac and liver disease, lupus, sarcoidosis, and so on). This review presents the first attempt to quantitatively understand the magnitude of the PLE in relation to the associated pathology for three different disease categories: 1) increased lymphatic pressure (e.g., lymphangiectasis); 2) diseases with mucosal erosions (e.g., Crohn’s disease); and 3) diseases without mucosal erosions (e.g., celiac disease). The PLE with lymphangiectasis results from rupture of the mucosal lymphatics, with retrograde drainage of systemic lymph into the intestinal lumen with the resultant loss of CD4 T cells, which is diagnostic. Mucosal erosion PLE results from macroscopic breakdown of the mucosal barrier, with the epithelial capillaries becoming the rate-limiting factor in albumin loss. The equation derived to describe the relationship between the reduction in serum albumin (C_P) and PLE indicates that gastrointestinal albumin clearance must increase by at least 17 times normal to reduce the C_P by half. The strengths and limitations of the two quantitative measures of PLE (⁵¹Cr-albumin or α₁-antitrypsin [αAT] clearance) are reviewed. αAT provides a simple quantitative diagnostic test that is probably underused clinically. The strong, unexplained correlation between minor decreases in C_P and subsequent mortality in seemingly healthy individuals raises the question of whether subclinical PLE could account for the decreased C_P and, if so, could the mechanism responsible for PLE play a role in the increased mortality? A large-scale study correlating αAT clearance with serum albumin concentrations will be required in order to determine the role of PLE in the regulation of the serum albumin concentration of seemingly healthy subjects.

Elevated serum autoantibodies against co-inhibitory PD-1 facilitate T cell proliferation and correlate with disease activity in new-onset systemic lupus erythematosus patients

Background

Programmed cell death protein 1 (PD-1) plays an important role in immune response regulation as a co-inhibitory signal during T cell activation. However, there is little known about the serum autoantibody profile of PD-1 in systemic lupus erythematosus (SLE), a disease characterized by the breakdown of immune tolerance to self-antigens and an excessive production of autoantibodies. Thus, we aim to investigate the serum levels and function of anti-PD-1 in patients with new-onset SLE.

Methods

Serum levels of anti-PD-1 IgG and IgM isotypes were detected in new-onset SLE patients (n = 90), rheumatoid arthritis (n = 50), primary Sjogren’s syndrome (n = 50), ankylosing spondylitis (n = 25), and healthy controls (HC) (n = 80) using an enzyme-linked immunosorbent assay (ELISA). The correlation of anti-PD-1 with clinical characteristics and laboratory parameters of patients with new-onset SLE was analyzed. The effects of purified anti-PD-1 IgG from SLE patients on T cell proliferation were measured using flow cytometry.

Results

The data revealed increased levels of anti-PD-1 IgG, but not IgM, especially in new-onset SLE patients, and the positive rate of anti-PD-1 IgG was 30 (33.3%). The level of anti-PD-1 IgG was closely associated with malar rash (OR = 15.773), arthritis (OR = 22.937), serositis (OR = 16.008), hematological (OR = 35.187), renal (OR = 8.306), and neurological involvement (OR = 37.282). Moreover, the serum levels of anti-PD-1 IgG were positively correlated with the SLE disease activity index (SLEDAI) score (r = 0.296, p = 0.0046) and the erythrocyte sedimentation rate (ESR) (r = 0.2446, p = 0.0201). In vitro examination showed that purified anti-PD-1 IgG obtained from SLE patients enhanced T cell proliferation when co-cultured with dendritic cells (DCs).

Conclusions

The current study indicates, for the first time, that the serum levels of co-inhibitor autoantibodies against PD-1 are elevated in new-onset SLE patients and are associated with disease activity in SLE. Autoantibodies against PD-1, facilitating T cell proliferation, revealed a new insight into the function of negative regulation signals involved in the pathogenesis of SLE.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1258-4) contains supplementary material, which is available to authorized users.

Regulatory T Cells Show Dynamic Behavior During Late Pregnancy, Delivery, and the Postpartum Period

Regulatory T cells (Tregs) are critical immunomodulators during early pregnancy by preventing maternal T-cell activation against fetal cells. However, how populations of maternal Tregs vary during and after pregnancy in humans is still unclear. Therefore, we investigated Treg subsets in the peripheral blood of pregnant women from late pregnancy through the postpartum period. To accomplish this, the following circulating Treg subsets were analyzed in 43 healthy pregnant women and 35 nonpregnant women by flow cytometry during the third trimester, on the day of delivery, and postpartum: CD4^DimCD25^Hi, CD4⁺CD25^HiFoxp3⁺, and CD4⁺CD25^HiCD127^-/dim. Additionally, the expression levels of the transcription factor Foxp3 in CD4^DimCD25^Hi Treg were analyzed. We have found that CD4^DimCD25^Hi Treg subset significantly decreased in the pregnant women on the day of delivery relative to the third trimester ( P < .05), and that all Treg subsets significantly increased postpartum compared to the third trimester and the day of delivery ( P < .05). Moreover, the Foxp3 expression ratios within the CD4^DimCD25^Hi Treg subset decreased during pregnancy and until delivery compared to those measured in the nonpregnant women and significantly increased postpartum compared to the third trimester and the day of delivery ( P < .05). Thus, despite their established role in offering immunoprotection to the fetus in early pregnancy, the number of circulating Tregs also varies from late pregnancy to the postpartum period. Our results offer an explanation for the possible effects of pregnancy on the clinical outcomes of some autoimmune diseases during the postpartum period.

CD4(+)CD25(+)CD127(-) and CD4(+)CD25(+)Foxp3(+) Regulatory T Cell Subsets in Mediating Autoimmune Reactivity in Systemic Lupus Erythematosus Patients

The available clinical as well as experimental studies implicate participation of T regulatory (Treg) subsets in the pathogenesis and course of systemic lupus erythematosus (SLE). Introduction of the CD4(+)CD25(+)CD127(-) and CD4(+)CD25(+)Foxp3(+) regulatory subpopulations analysis into immunological processes assessment and disease activation prognosis in patients with lupus nephritis (LN) may improve monitoring of disease activity and enable an early, and thus more effective, therapeutic treatment. The main goal of the study was to investigate whether the quantitative changes of Treg subpopulations are related to the clinical status of patients with LN. Fifty-four adult SLE patients divided into two groups according to their SLEDAI and renal SLEDAI scores were enrolled into the study. Subpopulations of CD4(+)CD25(+)CD127(-) and CD4(+)CD25(+)Foxp3(+) phenotypes were determined by flow cytometry. The control group had higher absolute number of CD4(+)CD25(+)Foxp3(+) cells compared with the study group (p < 0.001). Also, significant inverse correlation in the absolute number of CD4(+)CD25(+)Foxp3(+) cells and SLEDAI score was observed. There were significant differences in the percentage and absolute number of CD4(+)CD25(+)Foxp3(+) lymphocytes between active and non-active LN groups. The study group had statistically lower values of CD4(+)CD25(+)CD127(-) cells, both in the percentage (p < 0.001) as well as their absolute number (p = 0.014) compared to the control group. There were also statistically significant positive correlations between the absolute number of CD4(+)CD25(+)CD127(-) and CD4(+)CD25(+)Foxp3(+) Tregs.

IN CONCLUSION

(1) reduction in the number of regulatory CD4(+)CD25(+)Foxp3(+) cells is a promising indicator of the activity of SLE, particularly of renal involvement; (2) determination of the number of regulatory cells using the CD4(+)CD25(+)CD127(-) phenotype is unreliable in patients with SLE.

A Short Peptide That Mimics the Binding Domain of TGF-β1 Presents Potent Anti-Inflammatory Activity

The transforming growth factor beta 1 (TGF-β1) is a pleiotropic cytokine with multiple roles in development, wound healing, and immune regulation. TGF-β1-mediated immune dysfunction may lead to pathological conditions, such as inflammation. Chronic inflammatory process is characterized by a continuous release of pro-inflammatory cytokines, and the inhibition or the blockage of these cytokines signaling pathways are considered a target treatment. In this context, despite the high numbers of TGF-β-targeted pathways, the inducible regulatory T cells (iTreg) to control inflammation seems to be a promising approach. Our aim was to develop novel peptides through phage display (PhD) technology that could mimic TGF-β1 function with higher potency. Specific mimetic peptides were obtained through a PhD subtraction strategy from whole cell binding using TGF-β1 recombinant as a competitor during elution step. We have selected a peptide that seems to play an important role on cellular differentiation and modulation of TNF-α and IL-10 cytokines. The synthetic pm26TGF-β1 peptide tested in PBMC significantly down-modulated TNF-α and up-regulated IL-10 responses, leading to regulatory T cells (Treg) phenotype differentiation. Furthermore, the synthetic peptide was able to decrease leukocytes rolling in BALB/C mice and neutrophils migration during inflammatory process in C57BL/6 mice. These data suggest that this peptide may be useful for the treatment of inflammatory diseases, especially because it displays potent anti-inflammatory properties and do not exhibit neutrophils’ chemoattraction.

The immune suppressive function of transforming growth factor-β (TGF-β) in human diseases

Transforming growth factor-β (TGF-β) functions as an immune suppressor by influencing immune cells' development, differentiation, tolerance induction and homeostasis. In human diseases, TGF-β has been revealed as an essential regulator of both innate and adaptive functions in autoimmune diseases. Furthermore, it plays a significant role in cancer by inhibiting immunosurveillance in the tumor-bearing host. A variety of TGF-β neutralizing anti-cancer therapies have been investigated based on the role of TGF-β in immunosuppression. New studies are focusing on combining TGF-β blockade with tumor vaccinations and immunogene therapies.

Expansion of regulatory GITR+CD25 low/-CD4+ T cells in systemic lupus erythematosus patients

Introduction

CD4⁺CD25^low/-GITR⁺ T lymphocytes expressing forkhead box protein P3 (FoxP3) and showing regulatory activity have been recently described in healthy donors. The objective of the study was to evaluate the proportion of CD4⁺CD25^low/-GITR⁺ T lymphocytes within CD4⁺ T cells and compare their phenotypic and functional profile with that of CD4⁺CD25^highGITR⁻ T lymphocytes in systemic lupus erythematosus (SLE) patients.

Methods

The percentage of CD4⁺CD25^low/-GITR⁺ cells circulating in the peripheral blood (PB) of 32 patients with SLE and 25 healthy controls was evaluated with flow cytometry. CD4⁺CD25^low/-GITR⁺ cells were isolated with magnetic separation, and their phenotype was compared with that of CD4⁺CD25^highGITR⁻ cells. Regulatory activity of both cell subsets was tested in autologous and heterologous co-cultures after purification through a negative sorting strategy.

Results

Results indicated that CD4⁺CD25^low/-GITR⁺ cells are expanded in the PB of 50% of SLE patients. Expansion was observed only in patients with inactive disease. Phenotypic analysis demonstrated that CD4⁺CD25^low/-GITR⁺ cells display regulatory T-cell (Treg) markers, including FoxP3, cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), transforming growth factor-beta (TGF-β), and interleukin (IL)-10. In contrast, CD4⁺CD25^highGITR⁻ cells appear to be activated and express low levels of Treg markers. Functional experiments demonstrated that CD4⁺CD25^low/-GITR⁺ cells exert a higher inhibitory activity against both autologous and heterologous cells as compared with CD4⁺CD25^highGITR⁻ cells. Suppression is independent of cell contact and is mediated by IL-10 and TGF-β.

Conclusions

Phenotypic and functional data demonstrate that in SLE patients, CD4⁺CD25^low/-GITR⁺ cells are fully active Treg cells, possibly representing peripheral Treg (pTreg) that are expanded in patients with inactive disease. These data may suggest a key role of this T-cell subset in the modulation of the abnormal immune response in SLE. Strategies aimed at expanding this Treg subset for therapeutic purpose deserve to be investigated.

CD4(+)CD25(+) regulatory T cells as a therapeutic target in rheumatoid arthritis

CD4(+)CD25(+) T cells are regulatory T cells (CD4(+)CD25(+) Tregs), which can strengthen immune tolerance. They play a critical role in controlling the development of autoimmune diseases in animals and humans. Rheumatoid arthritis (RA) is a chronic autoimmune disease that affects the peripheral joints and eventually leads to joint destruction. Although the pathogenesis of RA remains unknown, it is supposed to be affected by autoreactive T cells and antibodies. At the same time, to make the CD4(+)CD25(+) T cells active and to increase the number of the cells are responsible in the therapy of RA in recent studies. Now, many techniques about expansion of Tregs in vitro have been established to overcome the problem of their limited numbers in vivo. It is important to carry out a study of induction or amplification of Tregs in vitro. Here, we review our current understanding of CD4(+)CD25(+) T cells in RA and the targeting of these cells in RA therapy.

Human CD4+CD25(high)CD127 (low/neg) regulatory T cells

CD4+CD25(high)CD127(low/neg) regulatory T cells (Tregs) play a critical role in the maintenance of peripheral tolerance and in controlling the development of autoimmune diseases. A combination of surface and intracellular markers, namely, CD25, CD39/CD73, CD62L, CD45RO, CD127, glucocorticoid-induced tumor necrosis factor receptor (GITR), CTLA-4, and the forkhead/winged helix transcription factor (FOXP3), has been used to characterize Tregs. Tregs suppress T effector responses mainly in a direct cell-cell contact manner. However, other mechanisms independent from this manner cannot be excluded entirely. It has been shown that Tregs can undergo limited expansion in vitro after the stimulation of TCR in the presence of exogenous cytokines, e.g., IL-2. Expanded Tregs retain their suppression function. Human Tregs have demonstrated their great potential to be used as a therapeutic intervention in preventing graft rejection and treating autoimmune diseases. In this chapter, we have given a review on how to characterize, isolate, expand Tregs and assess their suppressive functions.