Systemic lupus erythematosus exhibits a dynamic and continuum spectrum of effector/regulatory T cells

CD4 T lymphocyte subsets display heterogeneous susceptibility to apoptosis induced by serum from patients with systemic lupus erythematosus

BACKGROUND

Serum from systemic lupus erythematosus (SLE) patients has been shown to induce T-lymphocyte (TL) apoptosis. Given that different cells of the immune system display different sensitivity to apoptosis, we set to evaluate the in vitro effect of SLE serum on regulatory T-cells (Treg), Th17, Th1 and Th2 from SLE patients and healthy controls.

METHODS

Peripheral blood mononuclear cells from SLE patients or normal controls were exposed to a pool of sera from SLE patients or normal controls. Annexin V was used to label cells in apoptosis or necrosis. Annexin V-labeled Treg, Th17, Th1 and Th2 cells were determined using flow cytometry.

RESULTS

Total CD3 + and CD4 + cells from SLE patients showed higher frequency of spontaneous apoptosis/necrosis, whereas Th1 cells from SLE patients presented reduced spontaneous apoptosis/necrosis rate as compared with cells from controls. Incubation with SLE serum induced increased frequency of apoptotic/necrotic CD3 + , CD4 + and Th2 cells from normal controls or from SLE patients as compared with cultures incubated with normal human serum (NHS) or without human serum at all. Incubation with SLE serum did not increase the apoptosis/necrosis rate in Th1 or Th17 cells. Treg cells from SLE patients were more prone to apoptosis/necrosis induced by SLE serum than Treg cells from normal individuals. Th1, Th2, and Th17 cells presented increased apoptosis rates in cultures without human serum.

CONCLUSION

Our findings indicate that the serum of patients with active SLE stimulates apoptosis of CD4 + T cells in general and exhibit differentiated effects on CD4 + T-cell subsets.

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

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

Immune modulation via T regulatory cell enhancement: Disease-modifying therapies for autoimmunity and their potential for chronic allergic and inflammatory diseases-An EAACI position paper of the Task Force on Immunopharmacology (TIPCO)

Therapeutic advances using targeted biologicals and small-molecule drugs have achieved significant success in the treatment of chronic allergic, autoimmune, and inflammatory diseases particularly for some patients with severe, treatment-resistant forms. This has been aided by improved identification of disease phenotypes. Despite these achievements, not all severe forms of chronic inflammatory and autoimmune diseases are successfully targeted, and current treatment options, besides allergen immunotherapy for selected allergic diseases, fail to change the disease course. T cell-based therapies aim to cure diseases through the selective induction of appropriate immune responses following the delivery of engineered, specific cytotoxic, or regulatory T cells (Tregs). Adoptive cell therapies (ACT) with genetically engineered T cells have revolutionized the oncology field, bringing curative treatment for leukemia and lymphoma, while therapies exploiting the suppressive functions of Tregs have been developed in nononcological settings, such as in transplantation and autoimmune diseases. ACT with Tregs are also being considered in nononcological settings such as cardiovascular disease, obesity, and chronic inflammatory disorders. After describing the general features of T cell-based approaches and current applications in autoimmune diseases, this position paper reviews the experimental models testing or supporting T cell-based approaches, especially Treg-based approaches, in severe IgE-mediated responses and chronic respiratory airway diseases, such as severe asthma and COPD. Along with an assessment of challenges and unmet needs facing the application of ACT in these settings, this article underscores the potential of ACT to offer curative options for patients with severe or treatment-resistant forms of these immune-driven disorders.

Decreased Expression of Semaphorin 3A and Semaphorin 7A Levels and Its Association with Systemic Lupus Erythematosus

A growing body of data suggests that semaphorins are involved in both normal and pathological immune responses, as well as autoimmune pathologies. To investigate the plasma semaphorin 3A (Sema3A) and semaphorin 7A (Sema7A) levels in systemic lupus erythematosus (SLE) patients and their correlation with clinical manifestations and laboratory indexes, a two-step method was applied. First, 80 SLE patients and 80 healthy controls were recruited for comparing serum Sema3A and Sema7A concentrations. Second, 40 rheumatoid arthritis (RA) patients and 40 sjögren's syndrome (SS) patients were then included as disease controls. Plasma Sema3A and Sema7A concentrations were detected by ELISA. There were significant differences in Sema3A and Sema7A among four groups. When compared to healthy controls, both Sema3A and Sema7A levels were decreased in SLE and increased in RA; increased Sema3A level and decreased Sema7A level were found in SS. There were significant differences in Sema3A concentration between SLE and RA, SLE and SS. Moreover, there were significant differences in Sema7A level between SLE and RA, SS and RA. However, no significant differences in Sema3A between SS and RA and no significant differences in Sema7A between SS and SLE were observed. Both plasma Sema3A and Sema7A levels were correlated with anti-SSA and IgM. Area under curve (AUC) of the receiver operating characteristic (ROC) curve for Sema3A and Sema7A were 0.535 (0.455-0.613) and 0.671 (0.594-0.742), respectively. Aberrant Sema3A and Sema7A expression and their clinical associations in SLE suggest their important role in this disease.

Treg cells in autoimmunity: from identification to Treg-based therapies

Regulatory (Treg) cells are key regulators of inflammation and important for immune tolerance and homeostasis. A major progress has been made in the identification and classification of Treg cells. Due to technological advances, we have gained deep insights in the epigenetic regulation of Treg cells. The use of fate reporter mice allowed addressing the functional consequences of loss of Foxp3 expression. Depending on the environment Treg cells gain effector functions upon loss of Foxp3 expression. However, the traditional view that Treg cells become necessarily pathogenic by gaining effector functions was challenged by recent findings and supports the notion of Treg cell lineage plasticity. Treg cell stability is also a major issue for Treg cell therapies. Clinical trials are designed to use polyclonal Treg cells as therapeutic tools. Here, we summarize the role of Treg cells in selected autoimmune diseases and recent advances in the field of Treg targeted therapies.

Significant association of CD4+CD25+Foxp3+ regulatory T cells with clinical findings in patients with systemic lupus erythematosus

Background

Regulatory T (Treg) cells are one of the important mechanisms in maintaining self-tolerance and immune homeostasis. CD4⁺CD25⁺Foxp3⁺Treg is considered to have a role in the pathogenesis of systemic lupus erythematosus (SLE). However, the data reported is controversial, and a conclusive result has not been given thus far. The aim of the present study is to evaluate the role of CD4⁺Treg in SLE further.

Methods

The peripheral blood T cells (PBMCs) from patients with SLE and healthy controls were isolated, and followed by the isolation of CD3⁺T cells. The PBMCs were tested for the expressions of CD25 and Foxp3 molecules on the surface of CD4⁺T cells, and CD3⁺T cells were tested for their cytokine expressions including IFN-γ, TGF-β, and IL-10, with the method of flow cytometry. The correlations of test results with clinical features of the disease were evaluated by linear correlation analysis.

Results

CD4⁺CD25⁺ Foxp3⁺Treg decreased in SLE patients and was correlated with the SLE Disease Activity Index (SLEDAI), and a few immunological abnormalities, including anti-dsDNA antibody positive, IgG increase and C3 decrease, and types of tissue damage, including leukocytopenia and kidney damage. IFN-γ⁺ cells in the CD4⁺CD25⁺T subset fresh-isolated from SLE patients increased slightly, but IFN-γ-producing response to stimulation in CD4⁺CD25⁺T subset of SLE decreased. The number of TGF-β-producing cells in the CD4⁺CD25⁺T subset from SLE patients also decreased. While the percentages of CD4⁺CD25⁺IL-10⁺T subset in the CD3⁺T cells increased in SLE, however, these changes of cytokine expressions did not show any significant correlations with SLEDAI.

Conclusions

There is clear and definite evidence from the present study indicating the important role of CD4⁺CD25⁺Foxp3⁺Treg in the pathogenesis of SLE, for the abnormalities in functional cytokine productions of the CD4⁺CD25⁺ T subset, and for the feasibility of a CD4⁺CD25⁺Foxp3⁺Treg- based immunotherapy in SLE.

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 expression and clinical correlations of 4-1BB on peripheral CD4+ T cell subsets in patients with coronary artery disease. A cross-sectional pilot study

BACKGROUND

The expression of 4-1BB on peripheral regulatory T cells (Tregs) and conventional T cells (Tconvs) in coronary artery disease (CAD) patients is unknown. We aimed to investigate the expression and clinical correlations of 4-1BB on peripheral Tregs and Tconvs in CAD patients.

METHODS

Flow cytometry analysis was used to analyze 4-1BB expression on peripheral Tregs and Tconvs. We compared the percentages of 4-1BB on Tregs and Tconvs in the control (ctrl) group, the stable ischemic heart disease (SIHD) group, and the acute coronary syndrome (ACS) group. The correlations of 4-1BB expression on Tregs and Tconvs with the Gensini score and CRP were examined in the ACS group. The value of 4-1BB percentage on Tregs for predicting CAD in this cardiovascular risk population was also analyzed.

RESULTS

A total of 71 participants were enrolled in this study. In all the groups, the percentages of 4-1BB on Tregs were significantly higher than on Tconvs (all P < .05). After adjusting for sex, age, SBP, HbA1c and LDL, 4-1BB percentages on Tregs and Tconvs were significantly higher in the SIHD and ACS groups compared with the ctrl group (all P < .05). The ratio of 4-1BB percentage on Tregs to 4-1BB percentage on Tconvs was higher in the ACS group compared with the ctrl group (P = .010). In the ACS group, CRP was negatively correlated with the Tregs percentage (in CD4+ T cells) and the Tregs percentage to Tconvs percentage ratio. The Gensini score was positively correlated with the 4-1BB percentage on Tregs in the ACS group. Linear regression analysis showed 4-1BB percentage on Tregs independently predicted the Gensini score. Binary logistic regression showed CRP, HbA1c and 4-1BB percentage on Tregs independently predicted the development of CAD (SIHD+ACS) in the whole population.

CONCLUSION

4-1BB expression on peripheral Tregs and Tconvs was increased in SIHD and ACS patients. 4-1BB percentage on Tregs positively correlated with the severity of coronary artery stenosis in ACS patients. 4-1BB percentage on Tregs independently predicted the severity of coronary artery stenosis in an ACS population and development of CAD in a cardiovascular risk population.

The Proportion of Regulatory T Cells in Patients with Systemic Lupus Erythematosus: A Meta-Analysis

Background

Accumulating evidence indicates that a deficiency in or dysfunction of regulatory T cells (Tregs) is involved in the pathogenesis of systemic lupus erythematosus (SLE). As different markers have been used to identify Tregs, recent studies on the proportions of Tregs in SLE patients have generated controversial results. To clarify the status of Tregs in such patients, we determined the proportions of Tregs present during development of the disease, with special consideration of controversial cellular markers.

Methods

We identified studies reporting the proportions of Tregs in SLE patients by searching relevant databases through March 2018. Using the PRISMA guidelines, we performed a random effects meta-analysis of the frequencies of Tregs defined in different ways. Inconsistency was evaluated using the I-squared index (I²), and publication bias was assessed by examining funnel plot asymmetry using the Begger and Egger tests.

Results

Forty-four studies involving 2779 participants were included in the meta-analysis. No significant difference in the proportions of Tregs was evident between 1772 patients and 1007 controls [−0.191, (−0.552, 0.362), p = 0.613, I² = 95.7%]. We next conducted subanalyses based on individual definitions of Tregs. When the Treg definition included “FOXP3-positive” cells, the proportions did not differ between SLE patients and controls [−0.042, (−0.548, 0.632), p = 0.889, I² = 96.6%]; this was the case when Tregs were defined as either “CD25^low/−FOXP3⁺” or “CD25^high/+FOXP3⁺” cells. SLE patients had lower proportions of Tregs that were “single CD25-positive” [−1.428, (−1.982, −0.873), p < 0.001, I² = 93.4%] and “CD127-negative” [−1.093, (−2.002, −0.183), p = 0.018, I² = 92.6%] compared to controls. Tregs defined as “CD25^bright,” “CD25^bright/highCD127^low/−,” and “CD25^highCD127^low/−FOXP3⁺” did not differ in proportion between SLE patients and controls.

Conclusions

The Treg proportions varied by the cellular identification method used. The proportions of Tregs that were accurately identified and functionally validated fell among patients with SLE. Stricter definitions of Tregs are necessary when evaluating the status of such patients.

Dysregulation of innate and adaptive serum mediators precedes systemic lupus erythematosus classification and improves prognostic accuracy of autoantibodies

Systemic lupus erythematosus (SLE) is a complex autoimmune disease with a poorly understood preclinical stage of immune dysregulation and symptom accrual. Accumulation of antinuclear autoantibody (ANA) specificities is a hallmark of impending clinical disease. Yet, many ANA-positive individuals remain healthy, suggesting that additional immune dysregulation underlies SLE pathogenesis. Indeed, we have recently demonstrated that interferon (IFN) pathways are dysregulated in preclinical SLE. To determine if other forms of immune dysregulation contribute to preclinical SLE pathogenesis, we measured SLE-associated autoantibodies and soluble mediators in samples from 84 individuals collected prior to SLE classification (average timespan = 5.98 years), compared to unaffected, healthy control samples matched by race, gender, age (±5 years), and time of sample procurement. We found that multiple soluble mediators, including interleukin (IL)-5, IL-6, and IFN-γ, were significantly elevated in cases compared to controls more than 3.5 years pre-classification, prior to or concurrent with autoantibody positivity. Additional mediators, including innate cytokines, IFN-associated chemokines, and soluble tumor necrosis factor (TNF) superfamily mediators increased longitudinally in cases approaching SLE classification, but not in controls. In particular, levels of B lymphocyte stimulator (BLyS) and a proliferation-inducing ligand (APRIL) were comparable in cases and controls until less than 10 months pre-classification. Over the entire pre-classification period, random forest models incorporating ANA and anti-Ro/SSA positivity with levels of IL-5, IL-6, and the IFN-γ-induced chemokine, MIG, distinguished future SLE patients with 92% (±1.8%) accuracy, compared to 78% accuracy utilizing ANA positivity alone. These data suggest that immune dysregulation involving multiple pathways contributes to SLE pathogenesis. Importantly, distinct immunological profiles are predictive for individuals who will develop clinical SLE and may be useful for delineating early pathogenesis, discovering therapeutic targets, and designing prevention trials.

Abnormal phenotypic distribution of regulatory and effector T cells in octogenarian and nonagenarian women

INTRODUCTION

aging is associated with several immunologic changes. Regulatory (Treg) and effector T cells are involved in the pathogenesis of infectious, neoplastic, and autoimmune diseases. Little is known about the effects of aging on the frequency and function of these T cell subpopulations.

METHODS

peripheral blood mononuclear cells (PBMC) were obtained from 26 young (under 44 years old) and 18 elderly (above 80 years old) healthy women. T cell subpopulations were analyzed by flow cytometry.

RESULTS

elderly individuals had lower frequency of several activated effector T cell phenotypes as compared with young individuals: CD3+CD4+CD25+ (3.82±1.93 versus 9.53±4.49; p<0.0001); CD3+CD4+CD25+CD127+(2.39±1.19 versus 7.26±3.84; p<0.0001); CD3+CD4+CD25+ (0.41±0.22 versus 1.86±0.85, p<0.0001); and CD3+CD4+CD25highCD127+(0.06±0.038 versus 0.94±0.64, p<0.0001). Treg (CD3+CD4+CD25+CD127øFoxp3+) presented lower frequency in elderly individuals as compared to young adults (0.34±0.18 versus 0.76±0.48; p=0.0004) and its frequency was inversely correlated with age in the whole group (r=-0.439; p=0.013). The elderly group showed higher frequency of two undefined CD25øFoxp3+ phenotypes: CD3+CD4+CD25øFoxp3+(15.05±7.34 versus 1.65±1.71; p<0.0001) and CD3+CD4+CD25øCD127øFoxp3+(13.0±5.52 versus 3.51±2.87; p<0.0001).

CONCLUSIONS

the altered proportion of different T cell subsets herein documented in healthy elderly women may be relevant to the understanding of the immunologic behavior and disease susceptibility patterns observed in geriatric patients.

Th17 cells and CD4(+) multifunctional T cells in patients with systemic lupus erythematosus

INTRODUCTION/OBJECTIVE

Recent evidence suggests that abnormalities involving Th17 lymphocytes are associated with the pathophysiology of systemic lupus erythematosus (SLE). In addition, multifunctional T cells (MFT), i.e., those producing multiple cytokines simultaneously, are present in the inflammatory milieu and may be implicated in the autoimmune process observed in SLE. In the present study, we aimed to characterize the functional status of CD4(+) T cells in SLE by simultaneously determining the concentration of IL-2, IFN-γ and IL-17 in lymphocyte cultures under exogenous and self-antigenic stimuli.

PATIENTS AND METHODS

Eighteen patients with active disease, 18 with inactive disease, and 14 healthy controls had functional status of CD4(+) T cells analyzed.

RESULTS

We found that SLE patients presented a decreased number of total CD4(+) cells, an increased number of activated T cells, and an increased frequency of Th17 cells compared to healthy controls (HC). MFT cells had increased frequency in SLE patients and there was an increased frequency of tri-functional MFT in patients with active SLE compared with those with inactive SLE. Interestingly, MTF cells produced larger amounts of IFNγ than mono-functional T cells in patients and controls.

CONCLUSION

Taken together these data indicate the participation of recently activated Th17 cells and MTF cells in the SLE pathophysiology.

Activated T cells enhance interferon-α production by plasmacytoid dendritic cells stimulated with RNA-containing immune complexes

OBJECTIVES

Patients with systemic lupus erythematosus (SLE) have an ongoing interferon-α (IFN-α) production by plasmacytoid dendritic cells (pDCs). We investigated whether T cells can promote IFN-α production by pDCs.

METHODS

Human pDCs were stimulated with immune complexes (ICs) containing U1 small nuclear ribonucleic proteins particles and SLE-IgG (RNA-IC) in the presence of T cells or T cell supernatants. T cells were activated by anti-CD3/CD28 antibodies or in a mixed leucocyte reaction. IFN-α and other cytokines were determined in culture supernatants or patient sera with immunoassays. The effect of interleukin (IL) 3 and granulocyte-macrophage-colony-stimulating factor (GM-CSF) on pDCs was examined by the use of antibodies, and the expression of CD80/CD86 was determined using flow cytometry.

RESULTS

Activated T cells and supernatants from activated T cells increased IFN-α production by >20-fold. The stimulatory effect of T cell supernatants was reduced after depletion of GM-CSF (81%) or by blocking the GM-CSF receptor (55%-81%). Supernatant from activated T cells, furthermore, increased the frequency of CD80 and CD86 expressing pDCs stimulated with RNA-IC from 6% to 35% (p<0.05) and from 10% to 26% (p<0.01), respectively. Activated SLE T cells enhanced IFN-α production to the same extent as T cells from healthy individuals and a subset of patients with SLE had increased serum levels of GM-CSF.

CONCLUSIONS

Activated T cells enhance IFN-α production by RNA-IC stimulated pDCs via GM-CSF and induce pDC maturation. Given the increased serum levels of GM-CSF in a subset of patients with SLE, these findings suggest that activated T cells may upregulate type I IFN production in SLE.

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.

Imbalanced expression of functional surface molecules in regulatory and effector T cells in systemic lupus erythematosus

Regulatory T (TREG) cells play an important role in maintaining immune tolerance and avoiding autoimmunity. We analyzed the expression of membrane molecules in TREG and effector T cells in systemic lupus erythematosus (SLE). TREG and effector T cells were analyzed for the expression of CTLA-4, PD1, CD28, CD95, GITR, HLA-DR, OX40, CD40L, and CD45RO in 26 patients with active disease, 31 with inactive disease, and 26 healthy controls. TREG cells were defined as CD25^+/highCD127^Ø/lowFoxP3⁺, and effector T cells were defined as CD25⁺CD127⁺FoxP3^Ø. The ratio of TREG to effector T cells expressing GITR, PD1, HLA-DR, OX40, CD40L, and CD45RO was determined in the three groups. The frequency of TREG cells was similar in patients with SLE and controls. However, SLE patients had a decreased frequency of CTLA-4⁺TREG and CD28⁺TREG cells and an increased frequency of CD40L⁺TREG cells. There was a decrease in the TREG/effector-T ratio for GITR⁺, HLA-DR⁺, OX40⁺, and CD45RO⁺ cells, and an increased ratio of TREG/effector-T CD40L⁺ cells in patients with SLE. In addition, CD40L⁺TREG cell frequency correlated with the SLE disease activity index (P=0.0163). In conclusion, our findings showed several abnormalities in the expression of functionally critical surface molecules in TREG and effector T cells in SLE that may be relevant to the pathogenesis of this disease.

Abnormal expression pattern of the IL-2 receptor β-chain on CD4+ T cells in ANCA-associated vasculitis

BACKGROUND/AIM

ANCA-associated vasculitis (AAV) is a small-vessel vasculitis of autoimmune origin. In addition to autoantibodies, T cells have a pivotal pathophysiological role in this disease. T-cell homeostasis and immune tolerance critically depend on IL-2 and its receptor expressed by T cells. In this study, we investigated the IL-2 receptor (IL-2r) expression on CD4(+) T cells in AAV.

METHODS

Thirty patients with AAV and 15 age-matched healthy controls (HC) were enrolled. T cells from peripheral blood were analysed by flow cytometry for expression of the IL-2r α - and β-chain.

RESULTS

The IL-2r α-chain was overexpressed in AAV as compared to HC (36 ± 16% versus 20 ± 9%, P < 0.005). The IL-2r-β-chain expression was significantly reduced on CD25(+) CD4(+) T-cells and CD4(+)CD25(+)FoxP3(pos) regulatory T-cells (Tregs; AAV versus HC: 48 ± 14% versus 62 ± 9%, P = 0.002 and 38 ± 18% versus 68 ± 5%, P = 0.002). Low β -chain expression in AAV was associated with relapsing disease and systemic vasculitis with renal involvement.

CONCLUSION

The IL-2r expression pattern is abnormal in AAV. To our knowledge, we are the first to show that the β -chain expression is drastically diminished on T cells in AAV and related to a less favorable disease course. Given the indispensable function of the β -chain in IL-2 signaling of T cells, diminished expression may contribute to disturbed immune homeostasis in AAV.

The pro-inflammatory potential of T cells in juvenile-onset systemic lupus erythematosus

BACKGROUND

T cells are important to systemic lupus erythematosus (SLE) disease progression. This study determined the pro-inflammatory potential of T cells within the rare condition juvenile-onset SLE (JSLE).

METHOD

IL-17A and Th1/Th2-related cytokine concentrations were measured in plasma/serum from JSLE patients (n = 19, n = 11) and HC (n = 18, n = 7). IL17A, RORC, IL23 and IL23R mRNA were measured in peripheral blood mononuclear cells (PBMCs) from JSLE and healthy controls (HC) (n = 12). Th17-associated cytokine expression was analysed in the supernatant of CD3/CD28 activated JSLE (n = 7) and HC (n = 6) PBMCs.

RESULTS

JSLE plasma IL-17A level (21.5 ± 5.2 pg/ml) was higher compared to HC (7.2 ± 2.5 pg/ml, p = 0.028). No differences were found in Th1/Th2 cytokines levels. IL = 17A (p = 0.022), IL-6 (p = 0.028) and IL-21 (p = 0.003) concentrations were increased in supernatants from activated JSLE PBMCs. IL-17 F (p = 0.50) and IL-22 (p = 0.43) were also increased but were not statistically significant. IL17A and IL23 mRNA was significantly higher in JSLE PBMCs (p = 0.018 and p = 0.01).

CONCLUSION

JSLE T cells have an increased ability to secrete Th17 associated cytokines once activated, which could contribute to the pro-inflammatory disease phenotype seen in these patients.

The percentage of FoxP3+Helios+ Treg cells correlates positively with disease activity in systemic lupus erythematosus

OBJECTIVE

To assess the use of Helios in combination with FoxP3 as a superior method for identifying non-cytokine-producing human Treg cells in patients with systemic lupus erythematosus (SLE) and to determine if FoxP3+Helios+ Treg cells are maintained at normal levels in patients with clinically active disease.

METHODS

Peripheral blood mononuclear cells (PBMCs) were purified from the blood of healthy volunteer donors and from 52 consecutive patients with SLE of varying clinical activity (Systemic Lupus Erythematosus Disease Activity Index scores of 0, 2-4, and ≥ 5). PBMCs (either fresh or after 4 hours of stimulation for cytokine production) were then analyzed by flow cytometry for the expression of cell surface markers (CD4, CD25, CD127, and CD45RA) and transcription factors (FoxP3 and Helios), as well as for the production of cytokines (interleukin-2 and interferon-γ).

RESULTS

FoxP3+Helios+ Treg cells were found to be non-cytokine producing in both SLE patients and healthy controls. Patients with clinically active SLE had higher percentages of FoxP3+Helios+ Treg cells than did patients with inactive SLE or healthy controls. When corrected for the total CD4 cell count, the absolute numbers of FoxP3+Helios+ Treg cells in patients with moderately-to-highly active SLE were normal.

CONCLUSION

Previous reports of a deficiency in Treg cell number or function in SLE are limited by their use of CD25, either alone or in combination with other markers, to identify human Treg cells. Helios in combination with FoxP3 is a superior method for detecting all non-cytokine-producing Treg cells, irrespective of CD25 or CD45RA expression. Using this method, we showed that FoxP3+Helios+ Treg cell numbers are not reduced in patients with clinically active SLE.

Compensatory T-cell regulation in unaffected relatives of SLE patients, and opposite IL-2/CD25-mediated effects suggested by coreferentiality modeling

In human systemic lupus erythematosus (SLE), diverse autoantibodies accumulate over years before disease manifestation. Unaffected relatives of SLE patients frequently share a sustained production of autoantibodies with indiscriminable specificity, usually without ever acquiring the disease. We studied relations of IgG autoantibody profiles and peripheral blood activated regulatory T-cells (aTregs), represented by CD4⁺CD25^bright T-cells that were regularly 70–90% Foxp3⁺. We found consistent positive correlations of broad-range as well as specific SLE-associated IgG with aTreg frequencies within unaffected relatives, but not patients or unrelated controls. Our interpretation: unaffected relatives with shared genetic factors compensated pathogenic effects by aTregs engaged in parallel with the individual autoantibody production. To study this further, we applied a novel analytic approach named coreferentiality that tests the indirect relatedness of parameters in respect to multivariate phenotype data. Results show that independently of their direct correlation, aTreg frequencies and specific SLE-associated IgG were likely functionally related in unaffected relatives: they significantly parallelled each other in their relations to broad-range immunoblot autoantibody profiles. In unaffected relatives, we also found coreferential effects of genetic variation in the loci encoding IL-2 and CD25. A model of CD25 functional genetic effects constructed by coreferentiality maximization suggests that IL-2-CD25 interaction, likely stimulating aTregs in unaffected relatives, had an opposed effect in SLE patients, presumably triggering primarily T-effector cells in this group. Coreferentiality modeling as we do it here could also be useful in other contexts, particularly to explore combined functional genetic effects.

CD4+CD25+ regulatory T cells in systemic sclerosis and other rheumatic diseases

Systemic sclerosis (SSc) is a generalized connective tissue disorder, characterized by a wide spectrum of microvascular and immunological abnormalities, leading to a progressive thickening and fibrosis of the skin and other organs, such as the lungs, GI tract, heart and kidneys. SSc is thought to be an autoimmune disease owing to the presence of high affinity antibodies and possible clinical overlap with other autoimmune diseases such as systemic lupus erythematosus and rheumatoid arthritis. Autoimmune diseases arise because of a breakdown in immunological self tolerance. Self tolerance is maintained via multiple regulatory mechanisms within the immune system, including the thymic deletion of self-reactive T cells and mechanisms of peripheral tolerance. In recent years, the presence of CD4(+)CD25(+)FOXP3(+) Tregs has been identified as a major mechanism of peripheral tolerance, and accumulating evidence indicates that alterations in Treg frequencies and/or function may contribute to autoimmune diseases. Here, we will review recent data on the percentage, function and phenotype of CD4(+)CD25(+) Tregs in rheumatic disease, and discuss how recent developments may guide research in this area in SSc.