Decrease of regulatory T cells in patients with systemic lupus erythematosus

Clinical significance of antinuclear antibody as prognostic marker for first-line pembrolizumab in advanced non-small cell lung cancer

BACKGROUND

The relationship between antinuclear antibody (ANA) and the efficacy of programmed death-1 (PD-1) blockade remains controversial. Here, we investigated the prognostic significance of ANA titer in patients with non-small cell lung cancer (NSCLC) receiving pembrolizumab monotherapy as the first-line treatment, compared with that of platinum-based chemotherapy with PD-1 blockade.

METHODS

Our clinical data based on the ANA titer (1:80) were retrospectively reviewed for patients with advanced NSCLC, who were treated with first-line pembrolizumab monotherapy and platinum-based chemotherapy with PD-1 blockade. Immunohistochemical staining for tumor-infiltrating lymphocytes such as CD4, CD8 and Foxp3 was performed.

RESULTS

Among 106 patients treated with pembrolizumab, 19 (17.9%) tested high for ANA. Progression-free survival (PFS) and overall survival (OS) were significantly better in patients with high ANA than in those with low ANA, and high ANA was identified as an independent prognostic predictor, particularly in the subgroup with programmed death ligand-1 (PD-L1) ≥ 50%. However, no statistically significant difference in PFS and OS based on the ANA titer was observed in 59 patients treated with combinational chemotherapy and immunotherapy. High numbers of intratumoral Foxp3 and stromal CD8 were significantly associated with low ANA.

CONCLUSIONS

Assessment of preexisting ANA titers was useful to prognose PD-1 blockade as a first-line setting, particularly for the PD-L1 ≥ 50% subgroup, but not in the case of combined immunotherapy and chemotherapy.

Pathogenesis and novel therapeutics of regulatory T cell subsets and interleukin-2 therapy in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a heterogeneous multisystem inflammatory disease with wide variability in clinical manifestations. Natural arising CD4+ regulatory T cells (Tregs) play a critical role in maintaining peripheral tolerance by suppressing inflammation and preventing autoimmune responses in SLE. Additionally, CD8+ regulatory T cells, type 1 regulatory T cells (Tr1), and B regulatory cells also have a less well-defined role in the pathogenesis of SLE. Elucidation of the roles of various Treg subsets dedicated to immune homeostasis will provide a novel therapeutic approach that governs immune tolerance for the remission of active lupus. Diminished interleukin (IL)-2 production is associated with a depleted Treg cell population, and its reversibility by IL-2 therapy provides important reasons for the treatment of lupus. This review focuses on the pathogenesis and new therapeutics of human Treg subsets and low-dose IL-2 therapy in clinical benefits with SLE.

Allogeneic cord blood regulatory T cells decrease dsDNA antibody and improve albuminuria in systemic lupus erythematosus

Background

Lupus nephritis (LN) constitutes the most severe organ manifestations of systemic lupus erythematosus (SLE), where pathogenic T cells have been identified to play an essential role in 'helping' B cells to make autoantibodies and produce inflammatory cytokines that drive kidney injury in SLE. Regulatory T cells (Tregs), responsible for decreasing inflammation, are defective and decreased in SLE and have been associated with disease progression. We hypothesize that treatment with allogeneic, healthy Tregs derived from umbilical cord blood (UCB) may arrest such an inflammatory process and protect against kidney damage.

Methods

UCB-Tregs function was examined by their ability to suppress CellTrace Violet-labeled SLE peripheral blood mononuclear cells (PBMCs) or healthy donor (HD) conventional T cells (Tcons); and by inhibiting secretion of inflammatory cytokines by SLE PBMCs. Humanized SLE model was established where female Rag2-/-γc-/- mice were transplanted with 3 × 106 human SLE-PBMCs by intravenous injection on day 0, followed by single or multiple injection of UCB-Tregs to understand their impact on disease development. Mice PB was assessed weekly by flow cytometry. Phenotypic analysis of isolated cells from mouse PB, lung, spleen, liver and kidney was performed by flow cytometry. Kidney damage was assessed by quantifying urinary albumin and creatinine secretion. Systemic disease was evaluated by anti-dsDNA IgG Ab analysis as well as immunohistochemistry analysis of organs. Systemic inflammation was determined by measuring cytokine levels.

Results

In vitro, UCB-Tregs are able to suppress HD Tcons and pathogenic SLE-PBMCs to a similar extent. UCB-Tregs decrease secretion of several inflammatory cytokines including IFN-γ, IP-10, TNF-α, IL-6, IL-17A, and sCD40L by SLE PBMCs in a time-dependent manner, with a corresponding increase in secretion of suppressor cytokine, IL-10. In vivo, single or multiple doses of UCB-Tregs led to a decrease in CD8+ T effector cells in different organs and a decrease in circulating inflammatory cytokines. Improvement in skin inflammation and loss of hair; and resolution of CD3+, CD8+, CD20+ and Ki67+ SLE-PBMC infiltration was observed in UCB-Treg recipients with a corresponding decrease in plasma anti-double stranded DNA IgG antibody levels and improved albuminuria.

Conclusions

UCB-Tregs can decrease inflammatory burden in SLE, reduce auto-antibody production and resolve end organ damage especially, improve kidney function. Adoptive therapy with UCB-Tregs should be explored for treatment of lupus nephritis in the clinical setting.

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.

Impact of dietary vitamin D on immunoregulation and disease pathology in lupus-prone NZB/W F1 mice

Vitamin D (VD) deficiency is a highly prevalent worldwide phenomenon and is extensively discussed as a risk factor for the development of systemic lupus erythematosus (SLE) and other immune-mediated diseases. In addition, it is now appreciated that VD possesses multiple immunomodulatory effects. This study aims to explore the impact of dietary VD intake on lupus manifestation and pathology in lupus-prone NZB/W F1 mice and identify the underlying immunological mechanisms modulated by VD. Here, we show that low VD intake accelerates lupus progression, reflected in reduced overall survival and an earlier onset of proteinuria, as well higher concentrations of anti-double-stranded DNA autoantibodies. This unfavorable effect gained statistical significance with additional low maternal VD intake during the prenatal period. Among examined immunological effects, we found that low VD intake consistently hampered the adoption of a regulatory phenotype in lymphocytes, significantly reducing both IL-10-expressing and regulatory CD4⁺ T cells. This goes along with a mildly decreased frequency of IL-10-expressing B cells. We did not observe consistent effects on the phenotype and function of innate immune cells, including cytokine production, costimulatory molecule expression, and phagocytic capacity. Hence, our study reveals that low VD intake promotes lupus pathology, likely via the deviation of adaptive immunity, and suggests that the correction of VD deficiency might not only exert beneficial functions by preventing osteoporosis but also serve as an important module in prophylaxis and as an add-on in the treatment of lupus and possibly other immune-mediated diseases. Further research is required to determine the most appropriate dosage, as too-high VD serum levels may also induce adverse effects, possibly also on lupus pathology.

Methylprednisolone pulse therapy promotes the differentiation of regulatory T cells by inducing the apoptosis of CD4+ T cells in patients with systemic lupus erythematosus

OBJECTIVES

To investigate the differentiation of regulatory T cells (Tregs) induced by methylprednisolone (MP) pulse therapy in patients with Systemic Lupus Erythematosus (SLE).

METHODS

We enrolled 30 patients with SLE and analyzed peripheral blood mononuclear cells (PBMCs) before and after MP pulse therapy. Peripheral Tregs, apoptosis of PBMCs subsets, and TGFβ production by monocytes was quantified by flow cytometry. Proliferation and IFN-γ production of CD4⁺ T cells were measured. Furthermore, TGFβ1 production by human monocyte-derived macrophages (HMDM) stimulated with MP-treated CD4⁺ T cells were quantified by ELISA.

RESULTS

Peripheral Tregs was significantly increased after MP pulse therapy (6.76 ± 1.46% vs. 3.82 ± 1.02%, p < 0.01), with an expansion of Nrp1^- induced Tregs (4.54 ± 0.46% vs. 1.75 ± 0.38%, p < 0.01). Proliferation and IFN-γ production of CD4⁺ T cells were significantly decreased after MP pulse therapy. MP pulse therapy induced CD4⁺ T cell apoptosis (early apoptosis, 26.34 ± 3.54% vs. 14.81 ± 2.89%, p < 0.01) and TGFβ expression on monocytes (6.02% vs. 2.45%, p < 0.01). Furthermore, MP induced CD4⁺ T cell apoptosis in vitro, which stimulated HMDM to produce TGFβ. Moreover, elevated TGFβ level in supernatant from HMDM stimulated with MP-treated CD4⁺ T cells promoted Tregs differentiation.

CONCLUSIONS

MP pulse therapy induces CD4⁺ T cell apoptosis, which promotes monocytes to produce TGFβ and further facilitates Tregs differentiation. Newly-differentiated Tregs suppress proliferation and IFN-γ production of CD4⁺ T cells and contribute to immunoregulatory milieu after MP pulse therapy.

Deep immune phenotyping reveals similarities between aging, Down syndrome, and autoimmunity

[Figure: see text].

Cellular and Molecular Phenotypes of pConsensus Peptide (pCons) Induced CD8+ and CD4+ Regulatory T Cells in Lupus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with widespread inflammation, immune dysregulation, and is associated with the generation of destructive anti-DNA autoantibodies. We have shown previously the immune modulatory properties of pCons peptide in the induction of both CD4⁺ and CD8⁺ regulatory T cells which can in turn suppress development of the autoimmune disease in (NZB/NZW) F1 (BWF1) mice, an established model of lupus. In the present study, we add novel protein information and further demonstrate the molecular and cellular phenotypes of pCons-induced CD4⁺ and CD8⁺ T_reg subsets. Flow cytometry analyses revealed that pCons induced CD8⁺ T_reg cells with the following cell surface molecules: CD25^highCD28^{high and low} subsets (shown earlier), CD62L^high, CD122^low, PD1^low, CTLA4^low, CCR7^low and 41BB^high. Quantitative real-time PCR (qRT-PCR) gene expression analyses revealed that pCons-induced CD8⁺ T_reg cells downregulated the following several genes: Regulator of G protein signaling (RGS2), RGS16, RGS17, BAX, GPT2, PDE3b, GADD45β and programmed cell death 1 (PD1). Further, we confirmed the down regulation of these genes by Western blot analyses at the protein level. To our translational significance, we showed herein that pCons significantly increased the percentage of CD8⁺FoxP3⁺ T cells and further increased the mean fluorescence intensity (MFI) of FoxP3 when healthy peripheral blood mononuclear cells (PBMCs) are treated with pCons (10 μg/ml, for 24-48 hours). In addition, we found that pCons reduced apoptosis in CD4⁺ and CD8⁺ T cells and B220⁺ B cells of BWF1 lupus mice. These data suggest that pCons stimulates cellular, immunological, and molecular changes in regulatory T cells which in turn protect against SLE autoimmunity.

Plasma interleukin-22 level, variants in interleukin-22 gene polymorphism, and the severity of systemic lupus erythematosus among Egyptian pediatric and adolescents

OBJECTIVES

Our purpose was to investigate, for the first time, genotypes and alleles distribution of two single nucleotide polymorphisms (SNPs) of interleukin 22 (IL-22) (rs1012356 and rs2227485) in Egyptian pediatric and adolescents with systemic lupus erythematosus (SLE) and to evaluate the plasma IL-22 levels and their association with gene polymorphism and SLE risk and severity.

METHODS

The TaqMan™ SNP genotyping assay on a real-time polymerase chain reaction (PCR) system was employed to evaluate the polymorphism's genotypes. Plasma IL-22 levels were determined by using an enzyme-linked immunoabsorbent assay (ELISA).

RESULTS

The frequencies and genotypes of rs2227485 and rs1012356 in IL-22 between SLE patients and controls also haplotypes formed by the same SNPs revealed no statistically significant difference (p > 0.05). Otherwise, logistic regression analysis revealed that patients carrying rs1012356 "TA + AA" genotype had increased risk for prediction of SLE activity (OR = 1.610, 95% CI = 1.339-2.760, p = 0.034) by lowering plasma IL-22 level.

CONCLUSIONS

Among Egyptian pediatric and adolescents, we confirm a combined model "TA + AA" in rs1012356 (A/T) of IL-22 in regression analysis, as an independent predictor for SLE activity by lowering IL-22 plasma levels. Despite neither SNP rs2227485 A/G in IL-22 gene nor haplotypes formed by the same two SNPs (rs2227485 A/G and rs1012356 A/T) were significantly associated with the clinical and/or laboratory manifestations of SLE.

Haplotypes of FOXP3 genetic variants are associated with susceptibility, autoantibodies, and TGF-β1 in patients with systemic lupus erythematosus

The aim of this study was to evaluate the association of rs2232365 (-924 G > A) and rs3761548 (-3279 C > A) FOXP3 variants with systemic lupus erythematosus (SLE) susceptibility, TGF-β1 plasma levels, autoantibodies, and LN nephritis, and SLE disease activity index (SLEDAI). The study included 196 SLE female patients and 157 female controls. FOXP3 variants were determined with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Plasma levels of TGF-β1 were determined using immunofluorimetric assay. The AA genotype [OR: 2.650, CI 95%(1.070-6.564), p = 0.035] and A allele [OR: 2.644, CI 95%(1.104-6.333), p = 0.029] were associated with SLE diagnosis in the -3279 C > A. The A/A haplotype was associated with SLE [OR: 3.729, CI 95%(1.006-13.820), p = 0.049]. GCGC haplotype patients had higher TGF-β1 levels (p = 0.012) than other haplotypes. Patients with -924 AA genotype showed higher frequency of anti-dsDNA (p = 0.012) and anti-U1RNP (p = 0.036). The A/C haplotype had higher SLEDAI score [OR: 1.119, CI 95%(1.015-1.234), p = 0.024] and ACAC haplotype higher frequency of anti-dsDNA [OR: 3.026, CI 95%(1.062-8.624), p = 0.038], anti-U1RNP [OR: 5.649, CI 95%(1.199-26.610), p = 0.029] and nephritis [OR: 2.501, CI 95%(1.004-6.229), p = 0.049]. Our data demonstrate that the G/C haplotype provides protection for SLE. While the presence of allele A of both variants could favor autoimmunity, disease activity, and LN.

Double-Edged Sword: Interleukin-2 Promotes T Regulatory Cell Differentiation but Also Expands Interleukin-13- and Interferon-γ-Producing CD8+ T Cells via STAT6-GATA-3 Axis in Systemic Lupus Erythematosus

Interleukin-2 (IL-2) expands the depleted T regulatory (Treg) cell population, and it has emerged as a potential therapy in systemic lupus erythematosus (SLE). However, IL-2 administration may involve the risk of expanding unwanted pro-inflammatory cells. We herein studied the effects of IL-2 on pro-inflammatory cytokine production by CD4+ and CD8+ T cells in parallel with Treg development following CD3/CD28 co-stimulation. While Treg cells are depleted in SLE patients, their CD4+ T cells were poised to receive and activate IL-2 signaling as evidenced by upregulation of CD25 and enhanced IL-2-incued STAT5 phosphorylation during Treg differentiation. In patients with SLE, however, IL-2 also expanded CD8+ T cells capable of producing interleukin-5, interkeukin-13 (IL-13), and interferon-γ (IFN-γ) that occurred with enhanced expression of GATA-3 and phosphorylation of STAT6 but not STAT5. Our data pinpoint a safety signal for systemic administration of IL-2 and challenges a long-held conceptual platform of type 1 and 2 cytokine antagonism by newly documenting the IL-2-dependent development of IL-13 and IFN-γ double-positive (IL-13+IFNγ+) CD8+ T cells in SLE.

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.

Treg cells in health and autoimmune diseases: New insights from single cell analysis

Autoimmune diseases, such as Systemic Lupus Erythematosus (SLE) or Rheumatoid Arthritis (RA) are characterized by the breakdown of immunological tolerance. Defects of regulatory T cells have been described among the various mechanisms, that are important for the development of autoimmune diseases, due to their critical role as regulators of peripheral immune tolerance and homeostasis. Initially T suppressor cells have been described as one population of peripheral T cells. Based on new technological advances a new understanding of the heterogeneity of different Treg cell populations in the lymphoid and non-lymphoid tissue has evolved over the last years. While initially Foxp3 has been defined as the main master regulator of Treg cells, we have learned that Treg cells from various tissue can be identified by a specific transcriptomic and epigenetic signature. Epigenetic mechanisms allow Treg cell stability, but we have also learned that certain Treg subsets are plastic and can under specific circumstances even enhance autoimmunity and inflammatory processes. Quantitative and functional defects of Treg cells have been observed in a variety of autoimmune diseases. Due to our understanding of the nature of this cell population, Treg cells have been a target of new Treg based therapies, such as low-dose IL-2. In addition, ongoing clinical trials aim to test safety and efficacy of transferred, in vitro expanded Treg cells in patients with autoimmune diseases and transplant patients.

Leptin: an unappreciated key player in SLE

Leptin is the forerunner of the adipokine superfamily and plays a key role in regulating energy expenditure and neuroendocrine function. Researches into leptin put emphasize not only on the metabolic role but also its immunoregulatory effect on immune response through immunocyte activation and cytokine secretion. Leptin acts on receptors that are widespread throughout the body and that are expressed across many tissue types. As a consequence, the abnormal expression of leptin has been found to correlate with a number of diseases, including cancers, autoimmune diseases, and cardiovascular diseases. The significance of leptin in the development of autoimmune diseases is becoming increasingly prominent. Systemic lupus erythematosus (SLE) is a severe atypical autoimmune disease that causes damage to multiple organ systems. It is characterised by the following: impaired clearance of apoptotic cells, loss of tolerance to self-antigens, aberrant activation of T cells and B cells, and chronic inflammation. The heightened immunocyte response in SLE means that these physiological systems are particularly vulnerable to regulation by leptin in addition to being of great significance to the research field. Our current review provides insight into the regulatory roles that leptin plays on immune effector cells 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.

Principal component analysis reveals disconnect between regulatory cytokines and disease activity in Systemic Lupus Erythematosus

OBJECTIVE

Cytokine dysregulation contributes to inflammation and organ damage in Systemic Lupus Erythematosus (SLE). Principle Component Analysis (PCA) can determine which groups of cytokines have the most influence across disease activity states.

MATERIAL AND METHOD

A cross-sectional study of age- and gender-matched SLE patients (n = 100) and controls (n = 31). SLE patients had a median Systemic Lupus Erythematosus Disease Activity Index - 2000 (SLEDAI-2K) score of 6 (IQR 2, 11). IFN-γ, interleukin (IL)-1β, IL-4, IL-6, IL-10, IL-12, IL-17, BAFF, TNF-α, TGF-β1, MIP-1α, MIP-1β and MCP-1 levels were quantified by sandwich ELISA, and compared non-parametrically between groups. PCA was used to determine the principal components across controls, SLE patients in states of remission (SLEDAI-2K = 0), low disease activity (LDA = SLEDAI-2K from 1 ≤ x ≤ 4) or high disease activity (HDA = SLEDAI-2K > 4).

RESULTS

TGF-β1 (Rs -0.266, p = 0.005) and IL-1β (Rs -0.199, p = 0.004) inversely correlated, whereas BAFF correlated with increasing disease activity (Rs 0.465, p < 0.001). IL-1β, IL-4, IL-10, IL-12, IL-17, IFN-γ, MCP-1, and TNF-α were featured consistently in the PC1 of all study groups. PC1 changes from controls to SLE-HDA patients, included: the increased impact of IL-1β (from 0.58 to >0.95); increased impact of IL-6 in HDA (0.76); increased influence of MIP-1α (0.60) and MIP-1β (0.85); and the uncoupling of TGF-β1 (0.14). PC2 changes from healthy controls to the HDA state, included: the increased influence of BAFF (from -0.18 to 0.88); the oppositional effect of TGF-β1 (-0.36); and, the inclusion of MCP-1 (0.65). Levels of cytokine profiles were equivalent between controls and SLE patients (p > 0.18). BAFF was not associated with the cytokine profiles. TGF-β1 associated with Th1 (Rs 0.36), Th1 + Th17 (Rs 0.22), and inversely with Th17/Th2 (Rs -0.23) profiles. IL-1β associated with the proinflammatory (Rs 0.47), Th1 (Rs 0.55), Th2 (Rs 0.55), Th17 (Rs 0.51), Th1 + Th17 (Rs 0.56), Th2 + Treg (Rs 0.45), and inversely with the (Th1 + Th17 / Th2 + Treg) (Rs -0.22) and Th17/Th2 (Rs -0.27) profiles (all, p < 0.05).

CONCLUSION

Principal component analysis helped to describe the influence of complex cytokine interactions in SLE in a manner congruent with the wider literature. The typical univariate changes in BAFF and TGF-β1 levels with increasing levels of disease activity, were not the dominant factors (in PC1) in the PCA. The PCA demonstrated that IL-1β did not seem to change its regulatory function in SLE.

Belimumab restores Treg/Th17 balance in patients with refractory systemic lupus erythematosus

Belimumab, a specific inhibitor of the soluble B lymphocyte stimulator (BlyS), is the first biological drug approved by the United States Food and Drug Administration for the treatment of patients with active systemic lupus erythematosus (SLE) refractory to standard therapy. Given that an imbalance between regulatory T cells (Treg) and interleukin (IL)-17A-secreting T cells (Th17) has been reported in various autoimmune disorders, we assessed the frequency of both Treg and Th17 peripheral blood populations before and after belimumab administration in 20 patients with active SLE refractory to standard therapy. After six months of treatment, the mean SELENA-SLEDAI score as well as the mean anti-double-stranded DNA antibody titers were significantly decreased. In addition, we observed a significant increase in Treg percentages and a parallel, significant decrease in Th17 percentages, accompanied by significantly reduced serum levels of IL-21. In vitro studies showed that Treg purified from belimumab-treated patients were fully functional and displayed a suppressor function similar to that of Treg purified from healthy donors. Belimumab can restore Treg/Th17 balance in SLE patients with uncontrolled disease activity, and this results in decreased flare rate and reduced glucocorticoid dosage.

A Distinct T Follicular Helper Cell Subset Infiltrates the Brain in Murine Neuropsychiatric Lupus

Neuropsychiatric symptoms in systemic lupus erythematosus (SLE) are not uncommon, yet the mechanisms underlying disease initiation and progression in the brain are incompletely understood. Although the role of T cells in other lupus target organs such as the kidney is well defined, which T cells contribute to the pathogenesis of neuropsychiatric SLE is not known. The present study was aimed at characterizing the CD4 T cell populations that are present in the choroid plexus (CP) of MRL/MpJ-faslpr mice, the primary site of brain infiltration in this classic lupus mouse model which exhibits a prominent neurobehavioral phenotype. T cells infiltrating the CP of MRL/MpJ-faslpr mice were characterized and subset identification was done by multiparameter flow cytometry. We found that the infiltrating CD4 T cells are activated and have an effector phenotype. Importantly, CD4 T cells have a T follicular helper cell (T_FH) like phenotype, as evidenced by their surface markers and signature cytokine, IL-21. In addition, CD4 T_FH cells also secrete significant levels of IFN-γ and express Bcl-6, thereby conforming to a potentially pathogenic T helper population that can drive the disease progression. Interestingly, the regulatory axis comprising CD4 T regulatory cells is diminished. These results suggest that accumulation of CD4 T_FH in the brain of MRL/MpJ-faslpr mice may contribute to the neuropsychiatric manifestations of SLE, and point to this T cell subset as a possible novel therapeutic candidate.

Blockade of Treg Cell Differentiation and Function by the Interleukin-21-Mechanistic Target of Rapamycin Axis Via Suppression of Autophagy in Patients With Systemic Lupus Erythematosus

OBJECTIVE

The mechanistic target of rapamycin (mTOR) has become a therapeutic target in systemic lupus erythematosus (SLE). In T cells, mTOR plays a central role in lineage specification, including development of regulatory cells (Treg cells). This study sought to investigate whether mTOR is activated within Treg cells and whether this contributes to the depletion and dysfunction of Treg cells in patients with SLE.

METHODS

Activities of mTOR complexes 1 (mTORC1) and 2 (mTORC2) were examined by quantifying phosphorylation of translation initiation factor 4E-binding protein 1, S6 kinase, and Akt in SLE patients relative to age- and sex-matched female healthy control subjects. Polarization of Treg cells from naive CD4+ T cells was assessed in the presence of interleukin-6 (IL-6), IL-17, and IL-21. The suppressor function of sorted CD4+CD25+ Treg cells was measured by determining their impact on the proliferation of autologous CD4+CD25- responder T cells. Treg cell expression of FoxP3, GATA-3, and CTLA-4 was monitored by flow cytometry. Autophagy was assessed using immunoblotting of light chain 3 lipidation. The effect of mTOR blockade was evaluated by testing the impact of rapamycin treatment on Treg cell function.

RESULTS

SLE Treg cells exhibited increased activities of mTORC1 and mTORC2, whereas autophagy, the expression of GATA-3 and CTLA-4, and the suppressor function of Treg cells were diminished. IL-21, but not IL-6 or IL-17, blocked the development of Treg cells. IL-21 stimulated mTORC1 and mTORC2, and it abrogated the autophagy, differentiation, and function of Treg cells. Moreover, IL-21 constrained the expression of GATA-3 and CTLA-4 selectively in Treg cells. In turn, blockade of mTORC1 by 3-day rapamycin treatment enhanced transforming growth factor β production, while dual blockade of mTORC1 and mTORC2 by 4-week rapamycin treatment induced autophagy, restored the expression of GATA-3 and CTLA-4, and corrected Treg cell function.

CONCLUSION

IL-21-driven mTOR activation is a pharmacologically targetable checkpoint of the deficient autophagy that underlies Treg cell dysfunction in SLE.

[Lupus nephropathy: Insight in new treatments]

Systemic lupus erythematosus is a chronic autoimmune disease. Both acquired and innate immune systems are involved in the development of this systemic disease. Lupus nephritis usually is the most serious manifestation of systemic lupus erythematosus, with significant morbidity and mortality. The physiopathological development of the renal involvement of lupus has been increasingly elucidated over the years and various target therapies have recently been developed. After some physiopathological reminders, we discuss the conventional treatment of lupus nephritis as well as the various therapeutic advances, in particular the contribution and the place of the new target therapies in the treatment of the lupus nephritis.

Two separate effects contribute to regulatory T cell defect in systemic lupus erythematosus patients and their unaffected relatives

Forkhead box P3 (FoxP3)⁺ regulatory T cells (T_regs) are functionally deficient in systemic lupus erythematosus (SLE), characterized by reduced surface CD25 [the interleukin (IL)‐2 receptor alpha chain]. Low‐dose IL‐2 therapy is a promising current approach to correct this defect. To elucidate the origins of the SLE T_reg phenotype, we studied its role through developmentally defined regulatory T cell (T_reg) subsets in 45 SLE patients, 103 SLE‐unaffected first‐degree relatives and 61 unrelated healthy control subjects, and genetic association with the CD25‐encoding IL2RA locus. We identified two separate, uncorrelated effects contributing to T_reg CD25. (1) SLE patients and unaffected relatives remarkably shared CD25 reduction versus controls, particularly in the developmentally earliest CD4⁺FoxP3⁺CD45RO^–CD31⁺ recent thymic emigrant T_regs. This first component effect influenced the proportions of circulating CD4⁺FoxP3^highCD45RO⁺ activated T_regs. (2) In contrast, patients and unaffected relatives differed sharply in their activated T_reg CD25 state: while relatives as control subjects up‐regulated CD25 strongly in these cells during differentiation from naive T_regs, SLE patients specifically failed to do so. This CD25 up‐regulation depended upon IL2RA genetic variation and was related functionally to the proliferation of activated T_regs, but not to their circulating numbers. Both effects were found related to T cell IL‐2 production. Our results point to (1) a heritable, intrathymic mechanism responsible for reduced CD25 on early T_regs and decreased activation capacity in an extended risk population, which can be compensated by (2) functionally independent CD25 up‐regulation upon peripheral T_reg activation that is selectively deficient in patients. We expect that T_reg‐directed therapies can be monitored more effectively when taking this distinction into account.

Biological therapies in the treatment of cutaneous lupus erythematosus

Cutaneous lupus erythematosus (CLE) is an autoimmune skin disease occurring in association with or without systemic lupus erythematosus (SLE). Although antimalarials are widely used as the first-line systemic agent, refractory cases may benefit from additional immunomodulators, immunosuppressives, and biologics. An interest in biological therapies for CLE has emerged in recent years due to novel insight into the pathogenesis of CLE. These targets include B cells, T cells, and cytokines that are involved in immune system pathways. Currently belimumab is the only biological therapy approved for SLE and no biologic has been approved for CLE. While there is a paucity of high quality evidence with regard to biologics in CLE management, trials are currently being performed to determine their role.

The role of microRNA-31 and microRNA-21 as regulatory biomarkers in the activation of T lymphocytes of Egyptian lupus patients

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by familial aggregation and genetic predisposition. MicroRNAs (MiRNAs) serve as critical biomarkers in lupus patients because of their aberrant expression in different SLE stages. The study aimed to investigate the correlation of miR-31 and miR-21 with IL-2 in SLE patients as regulatory biomarkers in the activation of T lymphocytes of Egyptian lupus patients. Quantitative RT-PCR is carried out to estimate the expressions of miR-31 and miR-21, and IL-2 levels were determined using ELISA in plasma of 40 patients with SLE, 20 of their first-degree relatives and 20 healthy controls. The study also determined the systemic lupus erythematosus disease activity index (SLEDAI) score and proteinuria in SLE patients. The results revealed that miR-31 was lower expressed, while miR-21 was high expressed in SLE patients compared to their first-degree relatives and controls. MiR-31 was negatively correlated with SLEDAI and proteinuria in lupus patients, while miR-21 showed positive correlation with them. Also we found that there is a significant positive correlation between miR-31 and IL-2 in SLE patients, while miR-21 was negatively correlated with IL-2 level in patients. In conclusion, the study disclosed a significant association between miR-31 and miR-21 expression with IL-2 level in SLE patients. The regulatory biomarkers of miR-31 and miR-21 might have an impact on regulating IL-2 pathway expression and in turn on the activation of T lymphocytes in SLE.

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.

Cytokines and Effector/Regulatory Cells Characterization in the Physiopathology of Cutaneous Lupus Erythematous: A Cross-Sectional Study

We compared the presence of diverse cytokines and regulatory T and B cells in skin biopsies of discoid lupus erythematosus (DLE) and subacute cutaneous lupus erythematosus (SCLE). We included 19 patients with DLE, 13 with SCLE, 8 healthy controls, and 5 patients with hypertrophic scars. We assessed the CLASI activity score. To determine IL-22-producing cells and the subpopulation of CD4(+)/IL-17A(+)-, CD4(+)/IL-4(+)-, and CD4(+)/IFN-γ (+)-expressing T cells, CD123(+)/IDO(+) pDCs, CD25(+)/Foxp3(+) Tregs, and CD20(+)/IL-10(+)-producing B cells, an immunostaining procedure was performed. Also intracellular IL-22, IL-17, IL-4, IFN-γ, and Foxp3 in CD4 T cells, IL-10 in B cells, and IDO in pDCs were analyzed by flow cytometry in peripheral blood. The main cellular participation in both lupus groups was IL-17- and IL-22-producing cell responses both at skin and at peripheral blood but prevailed in DLE. The CLASI activity scores negatively correlated with Th22 subpopulation and positively correlated with CD25(+)/Foxp3(+) Treg cells. In conclusion a proinflammatory and regulatory imbalance coexists in cutaneous lupus, both responses being more intense in DLE.

Function of Treg Cells Decreased in Patients With Systemic Lupus Erythematosus Due To the Effect of Prolactin

Prolactin has different functions, including cytokine secretion and inhibition of the suppressor effect of regulatory T (Treg) cells in healthy individuals. Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by defects in the functions of B, T, and Treg cells. Prolactin plays an important role in the physiopathology of SLE. Our objective was to establish the participation of prolactin in the regulation of the immune response mediated by Treg cells from patients with SLE. CD4CD25CD127 cells were purified using magnetic beads and the relative expression of prolactin receptor was measured. The functional activity was evaluated by proliferation assay and cytokine secretion in activated cells, in the presence and absence of prolactin. We found that both percentage and function of Treg cells decrease in SLE patients compared to healthy individuals with statistical significance. The prolactin receptor is constitutively expressed on Treg and effector T (Teff) cells in SLE patients, and this expression is higher than in healthy individuals. The expression of this receptor differs in inactive and active patients: in the former, the expression is higher in Treg cells than in Teff cells, similar to healthy individuals, whereas there is no difference in the expression between Treg and Teff cells from active patients. In Treg:Teff cell cocultures, addition of prolactin decreases the suppressor effect exerted by Treg cells and increases IFNγ secretion. Our results suggest that prolactin plays an important role in the activation of the disease in inactive patients by decreasing the suppressor function exerted by Treg cells over Teff cells, thereby favoring an inflammatory microenvironment.

Memory Stem T Cells in Autoimmune Disease: High Frequency of Circulating CD8+ Memory Stem Cells in Acquired Aplastic Anemia

Memory stem T cells (TSCMs) constitute a long-lived, self-renewing lymphocyte population essential for the maintenance of functional immunity. Hallmarks of autoimmune disease pathogenesis are abnormal CD4(+) and CD8(+) T cell activation. We investigated the TSCM subset in 55, 34, 43, and 5 patients with acquired aplastic anemia (AA), autoimmune uveitis, systemic lupus erythematosus, and sickle cell disease, respectively, as well as in 41 age-matched healthy controls. CD8(+) TSCM frequency was significantly increased in AA compared with healthy controls. An increased CD8(+) TSCM frequency at diagnosis was associated with responsiveness to immunosuppressive therapy, and an elevated CD8(+) TSCM population after immunosuppressive therapy correlated with treatment failure or relapse in AA patients. IFN-γ and IL-2 production was significantly increased in various CD8(+) and CD4(+) T cell subsets in AA patients, including CD8(+) and CD4(+) TSCMs. CD8(+) TSCM frequency was also increased in patients with autoimmune uveitis or sickle cell disease. A positive correlation between CD4(+) and CD8(+) TSCM frequencies was found in AA, autoimmune uveitis, and systemic lupus erythematosus. Evaluation of PD-1, CD160, and CD244 expression revealed that TSCMs were less exhausted compared with other types of memory T cells. Our results suggest that the CD8(+) TSCM subset is a novel biomarker and a potential therapeutic target for AA.

Regulatory T Cell Responses to High-Dose Methylprednisolone in Active Systemic Lupus Erythematosus

BACKGROUND/PURPOSE

A slight increase in the proportion of circulating regulatory T (Treg) cells has been reported in systemic lupus erythematosus (SLE) patients taking oral prednisone. The effects of intravenous (IV) high dose methylprednisolone (MP) on Tregs have not yet been described, especially in active SLE.

METHODS

We prospectively analyzed the proportion of circulating CD4+ Treg cell subsets defined as follows: (1) naïve Treg (nTreg) FoxP3lowCD45RA+ cells; (2) effector Treg (eTreg) FoxP3highCD45RA- cells; and (3) non-suppressive FoxP3lowCD45RA- cells (non-regulatory Foxp3low T cells). Peripheral blood mononuclear cells of patients with active SLE were analyzed before the first infusion of IV high dose MP (day 0) and the following days (day 1, day 2, ±day 3 and ±day 8). The activity of SLE was assessed by the SLEDAI score.

RESULTS

Seventeen patients were included. Following MP infusions, the median (range) percentage of eTregs significantly increased from 1.62% (0.53-8.43) at day 0 to 2.80% (0.83-14.60) at day 1 (p = 0.003 versus day 0), 4.64% (0.50-12.40) at day 2 (p = 0.06 versus day 1) and 7.50% (1.02-20.70) at day 3 (p = 0.008 versus day 2), and declined to baseline values at day 8. Expanding eTreg cells were actively proliferating, as they expressed Ki-67. The frequency of non-regulatory FoxP3low T cells decreased from 6.39% (3.20-17.70) at day 0 to 4.74% (1.03-9.72) at day 2 (p = 0.005); nTreg frequency did not change. All patients clinically improved immediately after MP pulses. The absence of flare after one year of follow up was associated with a higher frequency of eTregs at day 2.

CONCLUSION

IV high dose MP induces a rapid, dramatic and transient increase in circulating regulatory T cells. This increase may participate in the preventive effect of MP on subsequent flares in SLE.

Functional dynamics of Foxp3⁺ regulatory T cells in mice and humans

Forkhead box protein 3 (Foxp3)(+) regulatory T (Treg) cells are critical mediators for the establishment of self-tolerance and immune homeostasis and for the control of pathology in various inflammatory responses. While Foxp3(+) Treg cells often control immune responses in secondary lymphoid tissues, they must also traffic to and persist within non-lymphoid tissues, where they integrate various environmental cues to coordinate and adapt their effector acitvities in these sites. In recent years, our group has made use of several mouse models, including the non-obese diabetic model of type 1 diabetes, to characterize the factors, which impact the homeostasis, function, and reprogramming potential of Foxp3(+) Treg cells in situ. In addition, our recent work shows that Foxp3(+) Treg cells possess distinct post-transcriptional mechanisms of gene regulation, namely mRNA translation, to modulate tissue-specific inflammatory responses. In humans, there is a pressing need for reliable markers of FOXP3(+) Treg cells and their related function in blood and tissue. Experimental progress in our group has enabled us to discover novel markers of FOXP3(+) Treg cell (dys)function and unique gene signatures that discriminate effector and Treg cells, as well as functional and dysfunctional FOXP3(+) Treg cells.

Regulatory T-cells in autoimmune diseases: challenges, controversies and--yet--unanswered questions

Regulatory T cells (Tregs) are central to the maintenance of self-tolerance and tissue homeostasis. Markers commonly used to define human Tregs in the research setting include high expression of CD25, FOXP3 positivity and low expression/negativity for CD127. Many other markers have been proposed, but none unequivocally identifies bona fide Tregs. Tregs are equipped with an array of mechanisms of suppression, including the modulation of antigen presenting cell maturation and function, the killing of target cells, the disruption of metabolic pathways and the production of anti-inflammatory cytokines. Treg impairment has been reported in a number of human autoimmune conditions and includes Treg numerical and functional defects and conversion into effector cells in response to inflammation. In addition to intrinsic Treg impairment, resistance of effector T cells to Treg control has been described. Discrepancies in the literature are common, reflecting differences in the choice of study participants and the technical challenges associated with investigating this cell population. Studies differ in terms of the methodology used to define and isolate putative regulatory cells and to assess their suppressive function. In this review we outline studies describing Treg frequency and suppressive function in systemic and organ specific autoimmune diseases, with a specific focus on the challenges faced when investigating Tregs in these conditions.

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.

IL-2 protects lupus-prone mice from multiple end-organ damage by limiting CD4-CD8- IL-17-producing T cells

IL-2, a cytokine with pleiotropic effects, is critical for immune cell activation and peripheral tolerance. Although the therapeutic potential of IL-2 has been previously suggested in autoimmune diseases, the mechanisms whereby IL-2 mitigates autoimmunity and prevents organ damage remain unclear. Using an inducible recombinant adeno-associated virus vector, we investigated the effect of low systemic levels of IL-2 in lupus-prone MRL/Fas(lpr/lpr) (MRL/lpr) mice. Treatment of mice after the onset of disease with IL-2-recombinant adeno-associated virus resulted in reduced mononuclear cell infiltration and pathology of various tissues, including skin, lungs, and kidneys. In parallel, we noted a significant decrease of IL-17-producing CD3(+)CD4(-)CD8(-) double-negative T cells and an increase in CD4(+)CD25(+)Foxp3(+) immunoregulatory T cells (Treg) in the periphery. We also show that IL-2 can drive double-negative (DN) T cell death through an indirect mechanism. Notably, targeted delivery of IL-2 to CD122(+) cytotoxic lymphocytes effectively reduced the number of DN T cells and lymphadenopathy, whereas selective expansion of Treg by IL-2 had no effect on DN T cells. Collectively, our data suggest that administration of IL-2 to lupus-prone mice protects against end-organ damage and suppresses inflammation by dually limiting IL-17-producing DN T cells and expanding Treg.

Mechanistic target of rapamycin complex 1 expands Th17 and IL-4+ CD4-CD8- double-negative T cells and contracts regulatory T cells in systemic lupus erythematosus

The mechanistic target of rapamycin (mTOR) is activated in CD4(-)CD8(-) double-negative (DN) T cells and its blockade is therapeutic in systemic lupus erythematosus (SLE) patients. Murine studies showed the involvement of mTOR complex 1 (mTORC1) and 2 (mTORC2) in the differentiation of Th1/Th17 cells and Th2 cells, respectively. In this study, we investigated the roles of mTORC1 and mTORC2 in T cell lineage development in SLE and matched healthy control (HC) subjects. mTORC1 activity was increased, whereas mTORC2 was reduced, as assessed by phosphorylation of their substrates phosphorylated S6 kinase 1 or phosphorylated S6 ribosomal protein and phosphorylated Akt, respectively. Rapamycin inhibited mTORC1 and enhanced mTORC2. IL-4 expression was increased in freshly isolated CD8(+) lupus T cells (SLE: 8.09 ± 1.93%, HC: 3.61 ± 0.49%; p = 0.01). DN T cells had greater IL-4 expression than CD4(+) or CD8(+) T cells of SLE patients after 3-d in vitro stimulation, which was suppressed by rapamycin (control: 9.26 ± 1.48%, rapamycin: 5.03 ± 0.66%; p < 0.001). GATA-3 expression was increased in CD8(+) lupus T cells (p < 0.01) and was insensitive to rapamycin treatment. IFN-γ expression was reduced in all lupus T cell subsets (p = 1.0 × 10(-5)) and also resisted rapamycin. IL-17 expression was increased in CD4(+) lupus T cells (SLE: 3.62 ± 0.66%, HC: 2.29 ± 0.27%; p = 0.019), which was suppressed by rapamycin (control: 3.91 ± 0.79%, rapamycin: 2.22 ± 0.60%; p < 0.001). Frequency of regulatory T cells (Tregs) was reduced in SLE (SLE: 1.83 ± 0.25%, HC: 2.97 ± 0.27%; p = 0.0012). Rapamycin inhibited mTORC1 in Tregs and promoted their expansion. Neutralization of IL-17, but not IL-4, also expanded Tregs in SLE and HC subjects. These results indicate that mTORC1 expands IL-4(+) DN T and Th17 cells, and contracts Tregs in SLE.

Imbalance of different types of CD4(+) forkhead box protein 3 (FoxP3)(+) T cells in patients with new-onset systemic lupus erythematosus

The aim of this study was to examine the numbers of CD4(+) CD25(-) forkhead box protein 3 (FoxP3)(+) , CD4(+) CD25(+) FoxP3(+) and CD4(+) CXCR5(+) FoxP3(+) T cells in patients with new-onset systemic lupus erythematosus (SLE). The numbers of CD4(+) CD25(-) FoxP3(+) , CD4(+) CD25(+) FoxP3(+) and CD4(+) CXCR5(+) FoxP3(+) T cells and the concentrations of serum interleukin (IL)-10 in 23 patients and 20 healthy controls (HC) were measured. The potential correlations between CD4(+) FoxP3(+) T cells, serum IL-10 and clinical measures in SLE patients were analysed. In comparison with that in the HC, significantly reduced numbers of CD4(+) CD25(+) FoxP3(+) and CD4(+) CXCR5(+) FoxP3(+) T cells, but increased numbers of CD4(+) CD25(-) FoxP3(+) T cells, were detected, accompanied by significantly lower levels of serum IL-10 in the patients. Stratification analysis indicated the numbers of CD4(+) CD25(+) FoxP3(+) and CD4(+) CXCR5(+) FoxP3(+) T cells and serum IL-10 levels in the patients with seropositive anti-dsDNA were significantly less than that in those with seronegative anti-dsDNA. Treatment with the anti-SLE therapy, particularly with prednisone, leflunomide and methotrexate, significantly improved the imbalance of these types of FoxP3(+) T cells and increased the concentrations of serum IL-10 in the drug-responding patients. The numbers of CD4(+) CD25(+) FoxP3(+) T cells were correlated negatively with the values of SLE disease activity index (SLEDAI), whereas the numbers of CD4(+) CD25(-) FoxP3(+) T cells were correlated positively with the values of SLEDAI, erythrocyte sedimentation rate (ESR) and serum C3. In addition, the concentrations of serum IL-10 were correlated positively with the numbers of CD4(+) CD25(+) FoxP3(+) T cells, but negatively with the values of SLEDAI, serum C3, CRP and ESR in these patients. Our data indicate that the imbalance of different types of FoxP3(+) CD4(+) T cells may contribute to the development of SLE in Chinese patients.

The peroxisome-proliferator activated receptor-γ agonist pioglitazone modulates aberrant T cell responses in systemic lupus erythematosus

PPAR-γ agonists can suppress autoimmune responses and renal inflammation in murine lupus but the mechanisms implicated in this process remain unclear. We tested the effect of the PPAR-γ agonist pioglitazone in human lupus and control PBMCs with regard to gene regulation and various functional assays. By Affymetrix microarray analysis, several T cell-related pathways were significantly highlighted in pathway analysis in lupus PBMCs. Transcriptional network analysis showed IFN-γ as an important regulatory node, with pioglitazone treatment inducing transcriptional repression of various genes implicated in T cell responses. Confirmation of these suppressive effects was observed specifically in purified CD4+ T cells. Pioglitazone downregulated lupus CD4+ T cell effector proliferation and activation, while it significantly increased proliferation and function of lupus T regulatory cells. We conclude that PPAR-γ agonists selectively modulate CD4+ T cell function in SLE supporting the concept that pioglitazone and related,-agents should be explored as potential therapies in this disease.

T-regs in autoimmune hepatitis-systemic lupus erythematosus/mixed connective tissue disease overlap syndrome are functionally defective and display a Th1 cytokine profile

Autoimmune hepatitis (AIH), a severe hepatopathy characterized by hypergammaglobulinaemia, autoantibodies and interface hepatitis, is occasionally associated with systemic autoimmune manifestations [systemic lupus erythematosus (SLE); mixed connective tissue disease (MCTD)]. In both AIH and SLE/MCTD numerical and/or functional impairment of regulatory T-cells (T-regs) is believed to favour autoimmunity. To investigate whether immune-tolerance breakdown profiles differ in patients with AIH and SLE/MCTD, isolated AIH or systemic autoimmunity, we studied phenotypic and functional features of T-regs in 10 patients with AIH-SLE/MCTD, 22 with AIH, 12 with SLE and 20 healthy subjects. Compared to health, CD4(pos)CD25(pos) cells were decreased in number and expressed high levels of the CD127 activation marker in all three disease groups; in AIH-SLE/MCTD and in SLE they displayed low levels of FOXP3. In AIH-SLE/MCTD, they also contained a high proportion of IFNγ positive cells, indicating a Th1 profile. Similarly, in AIH-SLE/MCTD, CD4(pos)CD25(pos)CD25(high) T-regs were reduced in number and contained an increased proportion of activated CD127(pos) and IFNγ(pos) cells. Such skewing towards a Th1 profile was also present at effector level, as a high frequency of IFNγ-producing cells was observed within AIH-SLE/MCTD CD4(pos)CD25(neg) responder cells. Impairment in suppressor function both of CD4(pos)CD25(pos) cells and CD4(pos)CD25(pos)CD127(neg) T-regs was observed in all three autoimmune conditions, but while addition of CD4(pos)CD25(pos)CD127(neg) T-regs decreased CD4(pos)CD25(neg) responder cell proliferation in healthy subjects and partially in AIH patients, it had no effect in AIH-SLE/MCTD and SLE patients. In conclusion, in AIH-SLE/MCTD T-regs display a distinctive phenotypic and functional signature, characterized by marked activation, elevated IFNγ production and by a profound impairment of suppressive function, suggesting that multiple autoimmune manifestations may derive from a complex defect of immune-regulation.

TLR7 and TLR9 in SLE: when sensing self goes wrong

Autoreactive B and T cells are present in healthy, autoimmunity-free individuals, but they are kept in check by various regulatory mechanisms. In systemic lupus erythematosus (SLE) patients, however, autoreactive cells are expanded, activated, and produce large quantities of autoantibodies, directed especially against nuclear antigens. These antibodies form immune complexes with self-nucleic acids present in SLE serum. Since self-DNA and self-RNA in the form of protein complexes can act as TLR9 and TLR7 ligands, respectively, TLR stimulation is suggested as an additional signal contributing to activation and/or modulation of the aberrant adaptive immune response. Data from mouse models suggest a pathogenic role for TLR7 and a protective role for TLR9 in the pathogenesis of SLE. Future investigations are needed to elucidate the underlying modulatory mechanisms and the role of TLR7 and TLR9 in the complex pathogenesis of human SLE.

Expansion of follicular helper T cells in the absence of Treg cells: implications for loss of B-cell anergy

The maintenance of B-cell anergy is essential to prevent the production of autoantibodies and autoimmunity. However, B-cell extrinsic mechanisms that regulate B-cell anergy remain poorly understood. We previously demonstrated that regulatory T (Treg) cells are necessary for the maintenance of B-cell anergy. We now show that in Treg-cell-deficient mice, helper T cells are necessary and sufficient for loss of B-cell tolerance/anergy. In addition, we show that the absence of Treg cells is associated with an increase in the proportion of CD4(+) cells that express GL7 and correlated with an increase in germinal center follicular helper T (GC-T(FH) ) cells. These GC-T(FH) cells, but not those from Treg-cell-sufficient hosts, were sufficient to drive antibody production by anergic B cells. We propose that a function of Treg cells is to prevent the expansion of T(FH) cells, especially GC-T(FH) cells, which support autoantibody production.

CD4⁺CD25⁺ regulatory T cells from MRL/lpr mice were functionally more active in vitro but did not prevent spontaneous as well as adriamycin-induced nephropathy in vivo

OBJECTIVE

The frequency and function of Tregs are important in the pathogenesis of SLE. Nonetheless, the function of Tregs is still controversial in SLE patients and lupus mouse models. In the present study, we investigated the suppressive function of Tregs from MRL/lpr mice in vitro and in vivo by using an alternative quantitative assay.

METHODS

We assessed the suppressive function of CD4(+)CD25(+) Tregs, the proliferative activity of CD4(+)CD25(-) effector T cells (Teffs) and the feeder activity of CD11c(+) dendritic cells (DCs), isolated from the spleens of MRL/lpr mice and wild-type (WT) MRL/+ mice, by carboxyfluorescein diacetate succinimidyl ester dilution assay stimulated with two distinct types of signals, weak and strong. In order to assess the protective function of Tregs from an immune-mediated disease in vivo, we induced renal damage by injecting adriamycin (ADN) into the mice.

RESULTS

The in vitro assay showed enhanced suppressive activity of Tregs and feeder activity of DCs, but far less proliferative activity of Teffs from MRL/lpr mice, compared with those from the WT mice. The in vivo study showed more severe ADN-induced nephropathy in MRL/lpr mice than in the WT mice, while mild interstitial nephritis had already begun spontaneously by 16 weeks in MRL/lpr mice.

CONCLUSION

It was suggested that Tregs from MRL/lpr mice were functionally competent and intrinsically more active in vitro, but they were not capable of preventing the ADN-induced as well as the spontaneously developing nephropathy in vivo.

Dual effects of statins therapy in systemic lupus erythematosus and SLE-related atherosclerosis: the potential role for regulatory T cells

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease associated with accelerated atherosclerosis independent of traditional risk factors. Statins, the 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase inhibitors, have been widely prescribed for hyperlipidemia, which could slow the atherosclerosis progression, and reduce cardiovascular disease events. Nonetheless, accumulated evidences suggested that statins exert immunomodulatory and anti-inflammatory functions independent of their lipid-lowering effects. By the virtue of pleiotropic immunomodulatory property, statins may be applied for the treatment of both autoimmunity and atherosclerosis in patients with SLE. Interestingly, it has been well documented that regulatory T cells (Tregs) are involved in the pathogenesis of SLE as well as atherosclerosis. Meanwhile, studies have shown that statins could induce augmented number of Tregs with increased functional inhibitory properties. Thus, we hypothesized that the effect of statins ameliorating lupus disease manifestations and lupus-mediated atherogenesis might be mediated, at least partly, via the activation of Tregs. To our knowledge, this is the first hypothesis focused on that Tregs might be involved in the immunomodulatory effect of statins on SLE and SLE-related atherosclerosis.

Total glucosides of paeony induces regulatory CD4(+)CD25(+) T cells by increasing Foxp3 demethylation in lupus CD4(+) T cells

Total glucosides of paeony (TGP), an active compound extracted from Paeony root, has been used in therapy for autoimmune diseases. However the molecular mechanism of TGP in the prevention of autoimmune response remains unclear. In this study, we found that TGP treatment significantly increased the percentage and number of Treg cells in lupus CD4(+) T cells. Further investigation revealed that treatment with TGP increased the expression of Foxp3 in lupus CD4(+) T cells by down-regulating Foxp3 promoter methylation levels. However, we couldn't observe similar results in healthy control CD4(+) T cells treated by TGP. Moreover, our results also showed that IFN-γ and IL-2 expression was enhanced in TGP-treated lupus CD4(+) T cells. These findings indicate that TGP inhibits autoimmunity in SLE patients possibly by inducing Treg cell differentiation, which may in turn be due to its ability to regulate the methylation status of the Foxp3 promoter and activate IFN-γ and IL-2 signaling.

Regulatory T cells: banned cells for decades

Regulatory T cells (Tregs), either thymic derived or peripherally induced, suppress a variety of physiological and pathological immune responses, and the absence of this cell subset has been shown to result in severe systemic autoimmunity. Since their acceptance almost two decades ago, intensive research aiming to characterize the phenotype, to elucidate the suppressive activity, and to decipher the migratory behavior of Tregs has been performed. A substantial number of studies, however, focused on understanding whether defects in Treg numbers and function contribute to the development and progression of inflammatory, autoimmune, and malignant disorders, and how Treg numbers/function might be modulated to treat patients with autoimmune diseases or cancer. In the skin, an organ that is constantly exposed to the environment, Tregs are known to be critically involved not only in the maintenance of skin homeostasis but also in the regulation of cutaneous immune responses. In this review, we present an overview on recent data concerning Treg development and expansion, the molecular mechanisms underlying their immunosuppressive activity, and the modulation of Treg function. Furthermore, we discuss the role of Tregs in cutaneous inflammatory and autoimmune disorders.

CD4+FOXP3+ T regulatory cells in human autoimmunity: more than a numbers game

Regulatory T cells (Treg) play a dominant role in suppression of autoimmune pathology, as rescue of Treg number and/or function in model systems can both prevent and reverse disease. These findings have generated a series of studies addressing the role of defects in Treg number and function in human autoimmunity. However, demonstrating global defects in Treg of individuals diagnosed with autoimmune diseases has been challenging. These challenges are founded, in part, in the complexity of human autoimmune diseases in which various genetic factors and environmental triggers contribute to disease susceptibility. Moreover, contribution of failed Treg-mediated suppression to pathogenesis can extend to multiple mechanisms. In this article, we discuss what is known with respect to the number and function of CD4(+)FOXP3(+) Treg in human autoimmunity, focusing on representative autoimmunediseases in which there are diverse Treg-mediated defects. We also highlight the need to better understand Treg plasticity and function in the context of autoimmunity.