Analysis of FOXP3+ regulatory T cell subpopulations in peripheral blood and tissue of patients with systemic lupus erythematosus

Diversity and function of regulatory T cells in health and autoimmune diseases

Regulatory T cell (Treg) play a pivotal role in immune regulation and maintaining host immune homeostasis. Treg heterogeneity, characterized by diverse gene expression profiles and functional states, is complex in both health and disease. Research reveals that Tregs are not a uniform population but exhibit diversity based on their origin, location, and functional status. This heterogeneity is crucial for understanding Treg roles in various pathological conditions. Dysfunctional Tregs are closely linked to the pathogenesis of autoimmune diseases, although the precise mechanisms remain unclear. The phenotypic and functional heterogeneity of Tregs is particularly significant in diseases such as systemic lupus erythematosus, multiple sclerosis, rheumatoid arthritis, inflammatory bowel disease, type 1 diabetes, psoriasis and autoimmune liver diseases. This review explores Treg origins, classifications, and heterogeneity in these conditions, aiming to provide new perspectives and strategies for diagnosis and treatment. Understanding Treg heterogeneity and plasticity promises to reveal novel therapeutic targets and advance precision immunotherapy development.

Low-dose interleukin-2 therapy in systemic lupus erythematosus

In systemic lupus erythematosus (SLE), T regulatory cells (Tregs) contribute to the inhibition of autoimmune responses by suppressing self-reactive immune cells. Interleukin (IL)-2 plays an essential role in the generation, function and homeostasis of the Tregs and is reduced in SLE. Several clinical studies, including randomized trials, have shown that low-dose IL-2 therapy in SLE patients is safe and effective and can reduce disease manifestations. This review discusses the rationale for the use of low-dose IL-2 therapy in SLE, the clinical responses in patients, and the effects of this therapy on different types of T cells. Considerations are made on the current and future directions of use of low-dose IL-2 regimens in SLE.

Skin infiltrating T-cell profile of drug reaction with eosinophilia and systemic symptoms (DRESS) reactions among HIV-infected patients

Introduction

Drug Reaction with Eosinophilia Systemic Symptoms (DRESS) is more common in persons living with HIV (PLHIV), and first-line anti-TB drugs (FLTDs) and cotrimoxazole are the commonest offending drugs. Limited data is available on the skin infiltrating T-cell profile among DRESS patients with systemic CD4 T-cell depletion associated with HIV.

Materials and methods

HIV cases with validated DRESS phenotypes (possible, probable, or definite) and confirmed reactions to either one or multiple FLTDs and/or cotrimoxazole were chosen (n = 14). These cases were matched against controls of HIV-negative patients who developed DRESS (n = 5). Immunohistochemistry assays were carried out with the following antibodies: CD3, CD4, CD8, CD45RO and FoxP3. Positive cells were normalized to the number of CD3+ cells present.

Results

Skin infiltrating T-cells were mainly found in the dermis. Dermal and epidermal CD4+ T-cells (and CD4+/CD8+ ratios) were lower in HIV-positive vs. negative DRESS; p < 0.001 and p = 0.004, respectively; without correlation to whole blood CD4 cell counts. In contrast, no difference in dermal CD4+FoxP3+ T-cells was found in HIV-positive vs. negative DRESS, median (IQR) CD4+FoxP3+ T-cells: [10 (0-30) cells/mm² vs. 4 (3-8) cells/mm², p = 0.325]. HIV-positive DRESS patients reacting to more than one drug had no difference in CD8+ T-cell infiltrates, but higher epidermal and dermal CD4+FoxP3+ T-cell infiltrates compared to single drug reactors.

Conclusion

DRESS, irrespective of HIV status, was associated with an increased skin infiltration of CD8+ T-cells, while CD4+ T-cells were lower in HIV-positive DRESS compared to HIV-negative DRESS skin. While inter-individual variation was high, the frequency of dermal CD4+FoxP3+ T-cells was higher in HIV-positive DRESS cases reacting to more than one drug. Further research is warranted to understand the clinical impact of these changes.

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

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

The emerging role of regulatory cell-based therapy in autoimmune disease

Autoimmune disease, caused by unwanted immune responses to self-antigens, affects millions of people each year and poses a great social and economic burden to individuals and communities. In the course of autoimmune disorders, including rheumatoid arthritis, systemic lupus erythematosus, type 1 diabetes mellitus, and multiple sclerosis, disturbances in the balance between the immune response against harmful agents and tolerance towards self-antigens lead to an immune response against self-tissues. In recent years, various regulatory immune cells have been identified. Disruptions in the quality, quantity, and function of these cells have been implicated in autoimmune disease development. Therefore, targeting or engineering these cells is a promising therapeutic for different autoimmune diseases. Regulatory T cells, regulatory B cells, regulatory dendritic cells, myeloid suppressor cells, and some subsets of innate lymphoid cells are arising as important players among this class of cells. Here, we review the roles of each suppressive cell type in the immune system during homeostasis and in the development of autoimmunity. Moreover, we discuss the current and future therapeutic potential of each one of these cell types for autoimmune diseases.

Downregulation of TIGIT Expression in FOXP3+Regulatory T Cells in Acute Coronary Syndrome

Objective

Little is currently known on the role of T-cell immunoglobulin and ITIM domain (TIGIT) expression in Foxp3+ regulatory T cells (TIGIT+Tregs) in acute coronary syndrome (ACS) patients. The aim of this study was to investigate the role and alterations of TIGIT+Tregs in ACS patients.

Methods

We enrolled 117 subjects, including 61 ACS patients, 26 chronic coronary syndrome (CCS) patients, and 30 control subjects without coronary artery disease. The quantification of TIGIT+Tregs was determined by flow cytometry; serum interleukin-6 (IL-6) and transforming growth factor-β (TGF-β) were also measured.

Results

TIGIT+Tregs expression was significantly lower in ACS patients compared with CCS and control patients (P<0.05). The expression of TIGIT+Tregs was comparable in patients with and without traditional risk factors (P>0.05). Logistic regression analysis revealed that TIGIT+Tregs levels are independent predictors of ACS (P<0.01). Receiver-operating characteristic (ROC) curve analysis showed the expression levels of TIGIT+Tregs had a discriminative power for ACS (P<0.01). IL-6 levels were increased (P<0.01), while TGF-β was decreased in ACS patients compared with CCS and control patients (P<0.01). Meanwhile, an inverse correlation between IL-6 and TIGIT+Tregs was observed (P<0.01), while a positive correlation between TGF-β and TIGIT+Tregs was found (P<0.05).

Conclusion

TIGIT+Tregs levels are significantly reduced in ACS, accompanied by upregulated IL-6 and downregulated TGF-β expression. The downregulated TIGIT+Tregs are independent predictors of ACS. These findings suggest that TIGIT+Tregs may have an anti-inflammatory and protective effect on ACS, and its decreased expression may be associated with atherosclerotic plaque destabilization.

New biomarkers in SLE: from bench to bedside

Biomarkers may have a diagnostic or monitoring value, or may predict response to therapy or disease course. The aim of this review is to discuss new serum and urinary biomarkers recently proposed for the diagnosis and management of SLE patients. Novel sensitive and specific assays have been proposed to evaluate complement proteins, ‘old’ biomarkers that are still a cornerstone in the management of this disease. Chemokines and lectins have been evaluated as surrogate biomarkers of IFN signature. Other cytokines like the B cell activating factor (BAFF) family cytokines are directly related to perturbations of the B cell compartment as key pathogenetic mechanism of the disease. A large number of urine biomarkers have been proposed, either related to the migration and homing of leukocytes to the kidney or to the local regulation of inflammatory circuits and the survival of renal intrinsic cells. The combination of traditional disease-specific biomarkers and novel serum or urine biomarkers may represent the best choice to correctly classify, stage and treat patients with SLE.

CC chemokine receptor 6 (CCR6) in the pathogenesis of systemic lupus erythematosus

The CC chemokine receptor 6 (CCR6) and its sole chemokine ligand, CCL20, are an intriguing pair that have been implicated in a growing number of inflammatory, autoimmune and malignant disease processes. Recent observations have also highlighted this chemokine axis in the regulation of humoral immune responses. Through this review article, we explore the emerging links of CCR6-CCL20 with an archetypal autoimmune disease of humoral dysregulation: systemic lupus erythematosus (SLE). CCR6 is expressed prominently on several immune cells involved in the pathogenesis of SLE, such as dendritic cells and T-helper 17 cells. CCR6's expression is correlated with disease activity and serological markers of disease severity, suggesting a possible role in disease pathogenesis. However, there are numerous holes in our understanding of the functions of CCR6 and CCL20, and future studies are required to determine if there are any diagnostic, prognostic or monitoring roles for these important molecules.

Efficient short-term expansion of human peripheral blood regulatory T cells for co-culture suppression assay

Regulatory T cells (Tregs) are a small population of CD4+ lymphocytes and play a key role as suppressors of the immune system, a role that can be identified by employing a co-culture suppression assay. Conventional protocol requires a long period of in vitro expansion of Treg numbers; hence, this study describes an establishment of a co-culture suppression assay using a short-term expansion of peripheral blood (PB) Tregs and autologous T cells (Tconvs) IL-2-pre-cultured in parallel for the same length of time, thereby obviating the need of freeze/thawed autologous Tconvs. Tregs and Tconvs were isolated from PB mononuclear cells employing magnetic bead-aided depletion of CD8+ cells followed by cell sorting of CD4+ CD25high+CD127low- (Treg) and CD4+ CD25-CD127+ (Tconv) cell populations. Following a 3-day co-cultivation period under optimized conditions, Treg suppression activity was monitored by comparing using flow cytometry the number of carboxyfluorescein succinimidyl ester-labeled Tconvs to that of Treg-minus control. The assay allowed significant differentiation between Treg suppression activity of patients with active rheumatoid arthritis and those in remission. This method should be more convenient and time-saving than the conventional Treg suppression assay in current use.

Mechanisms of action of low-dose IL-2 restoration therapies in SLE

Interleukin-2 (IL-2) shortage is a hallmark of Systemic Lupus Erythematosus (SLE). Importantly, clinical and preclinical studies demonstrate the potential clinical benefits of IL-2-based restoration therapies for the treatment of SLE. Here we discuss the immunological consequences of IL-2 deficiency in SLE patients and the mechanisms underlying the therapeutic effects of low-dose IL-2 regimens.

A role for Th1-like Th17 cells in the pathogenesis of inflammatory and autoimmune disorders

The T helper 17 (Th17) cells contain a dynamic subset of CD4+ T-cells that are able to develop into other different lineage subsets, including the Th1-like Th17 cells. These cells co-express retinoic acid-related orphan receptor gamma t (RORγt) and transcription factor T-box-expressed-in-T-cells (T-bet) and produce both interleukin (IL)-17 and interferon (IFN)-γ. Recent reports have shown that Th1-like Th17 cells play crucial roles in the pathogenesis of autoimmune diseases such as inflammatory bowel disease, multiple sclerosis and rheumatoid arthritis, as well as, some primary immunodeficiency with autoimmune features. Here, the actual mechanisms for Th17 cells plasticity to Th1-like Th17 cells are discussed and reviewed in association to the role that Th1-like Th17 cells have on inflammatory and autoimmune disorders.

Modulation of the Immune System for the Treatment of Glaucoma

Background:

At present intraocular pressure (IOP) lowering therapies are the only approach to treat glaucoma. Neuroprotective strategies to protect the retinal ganglion cells (RGC) from apoptosis are lacking to date. Substantial amount of research concerning the role of the immune system in glaucoma has been performed in the recent years. This review aims to analyse changes found in the peripheral immune system, as well as selected local changes of retina immune cells in the glaucomatous retina.

Methods:

By dividing the immune system into the innate and the adaptive immune system, a systematic literature research was performed to find recent approaches concerning the modulation of the immune system in the context of glaucoma. Also ClinicalTrials.gov was assessed to identify studies with a translational context.

Results:

We found that some aspects of the immune system, such as changes in antibody levels, changes in toll like receptor signalling, T cells and retinal microglial cells, experience more research activity than other areas such as changes in dendritic cells or macrophages. Briefly, results from clinical studies revealed altered immunoreactivities against retinal and optic nerve antigens in sera and aqueous humor of glaucoma patients and point toward an autoimmune involvement in glaucomatous neurodegeneration and RGC death. IgG accumulations along with plasma cells were found localised in human glaucomatous retinae in a pro-inflammatory environment possibly maintained by microglia. Animal studies show that antibodies (e.g. anti- heat shock protein 60 and anti-myelin basic protein) elevated in glaucoma patients provoke autoaggressive RGC loss and are associated with IgG depositions and increased microglial cells. Also, studies addressing changes in T lymphocytes, macrophages but also local immune responses in the retina have been performed and also hold promising results.

Conclusions:

This recapitulation of recent literature demonstrates that the immune system definitely plays a role in the pathogenesis of glaucoma. Multiple changes in the peripheral innate as well as adaptive immune system have been detected and give room for further research concerning valuable therapeutic targets. We conclude that there still is a great need to bring together the results derived from basic research analysing different aspects of the immune system in glaucoma to understand the immune context of the disease. Furthermore local immune changes in the retina of glaucoma patients still leave room for further therapeutic targets

Ratio of CD147high/CD147low in CD4+CD25+ T cells: A potential biomarker for early diagnosis and prediction of response to therapy for autoimmune diseases

Regulatory T cell (Treg cell) is an important immunosuppressive T cell subset and plays a dominant role in maintaining the immune balance in vivo. The function defects in Treg cells have been involved in the pathogenesis of many autoimmune diseases. The detection of Treg cell suppressive function is important for early diagnosis and prediction of response to treatment for autoimmune diseases. The traditional detection of Treg cell suppressive function needs at least 20 mL peripheral blood sample of patients and the results would be got in sixth day, therefore, it could not be widely applied in clinical. However, to find fast and simple detection method is very important. CD147 is a transmembrane protein and its expression is related to Treg cell suppressive function. Recent research has shown that the Treg cells with high CD147 expression have stronger suppressive function than which with low CD147 expression. In this work, we detected the ratio of CD147^high/CD147^low in CD4⁺CD25⁺ T cells in patients with active AS using fluorescence-activated cell sorter (FACS). The results show the ratio of CD147^high/CD147^low decreased obviously in patients with active AS compared with healthy controls, which reflects the suppressive function deficit of Treg cell. In the same time, the detection of the ratio of CD147^high/CD147^low needs only 150 μL peripheral blood sample and the result would be got in 4 h. We therefore hypothesize that the ratio of CD147^high/CD147^low is a good indicator for the Treg cell function, and it is especially suitable for early diagnosis and prediction of response to therapy targeted recovering Treg cell function in autoimmune diseases.

Targeting Regulatory T Cells to Treat Patients With Systemic Lupus Erythematosus

Regulatory T cells (Tregs) are central in integration and maintenance of immune homeostasis. Since breakdown of self-tolerance is a major culprit in the pathogenesis of systemic lupus erythematosus (SLE), restoration of the immune tolerance through the manipulation of Tregs can be exploited to treat patients with SLE. New information has revealed that Tregs besides their role in suppressing the immune response are important in tissue protection and regeneration. Expansion of Tregs with low-dose IL-2 represents an approach to control the autoimmune response. Moreover, control of Treg metabolism can be exploited to restore or improve their function. Here, we summarize the function and diversity of Tregs and recent strategies to improve their function in patients with SLE.

Saponins from Panax notoginseng leaves improve the symptoms of aplastic anemia and aberrant immunity in mice

Aplastic anemia (AA) is usually treated with immunosuppressive agents, but their efficacy and safety are not satisfactory. Panax notoginseng saponins (PNS) promote the proliferation of hematopoietic stem/progenitor cells. This study aimed to examine the effects of leaf PNS (LPNS) on hematopoiesis and T cells in mouse models of AA. The experiments were performed in normal mice and AA mice (controls, cyclosporine, and low, medium, and high doses of LPNS). Hematopoietic cells were counted using colony formation assays. The proportions of T cells were measured by flow cytometry. The ERK1/2, T-bet, GATA-3, FOXP3, and RORγ proteins were assessed by western blotting. Cytokines were measured using a cytometric bead array. AA mice showed impaired hematopoiesis, high activation of T cells, and decreased expression of T-bet, GATA-3, and FOXP3. LPNS attenuated the inflammation observed in AA mice, and significantly increased the number of hematopoietic progenitor cells. The proportions of Th2 and regulatory T cells and the protein levels of P-ERK1/2, GATA-3, and FOXP3 were increased in the AA + LPNS mice compared with the AA mice. In contrast, LPNS decreased the proportions of Th1 and Th17 cells and the protein expression of T-bet. LPNS and cyclosporine had similar effects, but of different amplitudes. These results suggest that LPNS have dual activities in AA: 1) promoting the proliferation of hematopoietic progenitor cells; and 2) modulating T cell immune functions, an activity similar to that of cyclosporine. Additional studies are necessary to confirm those results before clinical use.

CCR6+ Th cell distribution differentiates systemic lupus erythematosus patients based on anti-dsDNA antibody status

Background

Systemic lupus erythematosus (SLE) disease has been shown to be associated with the generation of multiple auto-antibodies. Among these, anti-dsDNA antibodies (anti-DNAs) are specific and play a pathogenic role in SLE. Indeed, anti-DNA⁺ SLE patients display a worse disease course. The generation of these pathogenic anti-DNAs has been attributed to the interaction between aberrant T helper (Th) cells and autoimmune B cells. Thus, in this study we have investigated whether CCR6⁺Th cells have the ability to differentiate SLE patients based on anti-DNA status, and if their distribution has any correlation with disease activity.

Methods

We recruited 25 anti-DNA⁺ and 25 anti-DNA⁻ treatment-naive onset SLE patients, matched for various clinical characteristics in our nested matched case-control study. CCR6⁺ Th cells and their additional subsets were analyzed in each patient by flow cytometry.

Results

Anti-DNA⁺ SLE patients specifically had a higher percentage of Th cells expressing CCR6 and CXCR3. Further analysis of CCR6⁺ Th cell subsets showed that anti-DNA⁺ SLE patients had elevated proportions of Th9, Th17, Th17.1 and CCR4/CXCR3 double-negative (DN) cells. However, the proportions of CCR6⁻ Th subsets, including Th1 and Th2 cells, did not show any association with anti-DNA status. Finally, we identified a correlation between CCR6⁺ Th subsets and clinical indicators, specifically in anti-DNA⁺ SLE patients.

Conclusions

Our data indicated that CCR6⁺ Th cells and their subsets were elevated and correlated with disease activity in anti-DNA⁺ SLE patients. We speculated that CCR6⁺ Th cells may contribute to distinct disease severity in anti-DNA⁺ SLE patients.

CCR6 signaling inhibits suppressor function of induced-Treg during gut inflammation

CCR6 is a G protein-coupled receptor (GPCR) that binds to a specific chemokine, CCL20. The role of CCR6-CCL20 is very well studied in the migration of immune cells, but the non-chemotaxis functions of CCR6 signaling were not known. Here, we show that during gut inflammation, the frequency of Foxp3⁺CD4⁺ T cells (Tregs) reduced in the secondary lymphoid tissues and CCR6⁺ Tregs enhanced the expression of RORγt. The peripheral blood mononuclear cells (PBMCs) of ulcerative colitis (UC) patients showed lower percentages of Foxp3⁺CD4⁺ T cells, as compared to healthy individuals, with CCR6⁺ Tregs showing higher RORγt expression as compared to CCR6^-Tregs. CCL20 inhibited the TGF-β1-induced Treg (iTreg) differentiation and directed them towards the pathogenic Th17-lineage in a CCR6-dependent manner. The iTreg that differentiated in the presence of CCL20 showed lower surface expression of suppressor molecules such as CD39, CD73 and FasL, and had impaired suppressive function. Furthermore, CCR6 signaling induced phosphorylation of Akt, mTOR, and STAT3 molecules in T cells. In conclusion, we have identified a new role of CCR6 signaling in the differentiation of iTregs during inflammation and gut autoimmunity.