Changes in Frequency and Activation Status of Major CD4+ T-Cell Subsets after Initiation of Immunosuppressive Therapy in a Patient with New Diagnosis Childhood-Onset Systemic Lupus Erythematosus

Aberrant phenotypes of circulating γδ-T cells may be involved in the onset of systemic lupus erythematosus

OBJECTIVE

Human gamma-delta T cells (γδ-T cells) play crucial roles in both innate and adaptive immune responses. However, much less is known about the immune status of γδT cells in systemic lupus erythematosus (SLE) patients. The objective of this study was to explore potential relationships between the frequency of γδ-T-cell subpopulations and disease activity, autoantibody titres and renal involvement in patients with SLE.

METHODS

Circulating γδ-T cells and their subsets (Vδ1+ T cells, Vδ2+ T cells and γδ-T-cell subpopulations defined by expression of surface receptors, including NKG2D, NKp30, NKp46 and PD-1), were identified via flow cytometry. Sixty active SLE patients were selected, including 41 new-onset and 19 relapsing cases. One hundred healthy controls (HCs) were enrolled as the control group. Percentages of these cell subsets in SLE patients and HCs and their relationships with disease activity were analysed. Twenty-two of the 41 new-onset SLE patients were assessed before and after treatment. Changes in the frequencies of these cell subsets and their relationships with renal involvement were also analysed.

RESULTS

Compared with that in HCs, the percentage of total γδ-T cells among CD3+ T cells in SLE patients was significantly lower. An imbalance in the proportions of Vδ1+ and Vδ2+ T cells among γδ-T cells was observed. The proportion of Vδ1+ T cells among γδ-T cells was significantly greater in SLE patients than in HCs, while the proportion of Vδ2+ T cells was significantly lower. Expression levels of PD-1, NKG2D, NKp30 and NKp46 in Vδ1+ T cells and Vδ2+ T cells from SLE patients were generally significantly increased, except for expression of NKG2D in Vδ2+ T cells. Moreover, Vδ2+ T cells, Vδ1+ T cells and Vδ1+PD-1+ T cells were associated with disease activity, and an increase in Vδ2+ T-cell frequency and a decrease in PD-1 expression by γδ-T cells might be associated with effective treatment. Interestingly, our results indicated that Vδ2+ T cells and their Vδ2+NKp30+ T-cell subpopulation might be associated with renal involvement in SLE.

CONCLUSION

A broad range of anomalies in the proportions of γδ-T-cell subsets and γδ-T cells in SLE patients may be involved in the pathogenesis of SLE. There is a strong association between Vδ2+ T cells and their Vδ2+NKp30+ T-cell subpopulation and LN occurrence. Our results indicate that γδ-T cells and their subpopulations might be key players in disease immunopathology and renal involvement in SLE.

Cell activation, PD-1 expression and in vitro cytokine production in patients with juvenile systemic lupus erythematosus

BACKGROUND

Juvenile systemic lupus erythematosus (jSLE) is known to be more severe and with a higher frequency of renal and central nervous system impairment when compared to systemic lupus erythematosus in adults. The study of immunological characteristics of jSLE patients might help to envisage better treatment strategies to reduce the burden of the disease.

OBJECTIVE

To characterize peripheral lymphocytes, assessing activation markers, and PD-1 expression on T cells; to evaluate in vitro cytokine expression upon stimulation in jSLE patients and age-matched controls.

METHODOLOGY

Eighteen jSLE patients on low disease activity and 25 matched healthy adolescents were evaluated for immune activation and PD-1 expression on peripheral blood lymphocytes by flow cytometry. Twenty-one cytokines were assessed by X-MAP technology after in vitro stimulation of peripheral blood with phytohemagglutinin.

RESULTS

jSLE patients had lower numbers of CD4 T, CD8 T, B, and NK cells; higher central memory CD8 T cell percentages were noted in jSLE adolescents in comparison with controls (p = 0.014). B cells subsets showed a higher percentage of exhausted memory subset than controls (p = 0.014). The expression of PD-1 on CD4 T and CD8 T cells did not show relevant changes in jSLE adolescents. After stimulation of peripheral blood, cell supernatant of jSLE patients showed a trend to lower concentrations of IL-10 (p=0.080) and higher concentrations of IL-23 (p = 0.063) than controls.

CONCLUSIONS

jSLE patients on low disease activity maintain lymphopenia of all subsets, with a B cell profile of exhaustion. Upon in vitro stimulation, peripheral blood cell supernatant showed a shift to IL-23, suggesting a role of inhibitors of this cytokine as another potential therapeutic target for those patients.

An Update on the Management of Childhood-Onset Systemic Lupus Erythematosus

Childhood-onset systemic lupus erythematosus (cSLE) is a prototype of a multisystemic, inflammatory, heterogeneous autoimmune condition. This disease is characterized by simultaneous or sequential organ and system involvement, with unpredictable flare and high levels of morbidity and mortality. Racial/ethnic background, socioeconomic status, cost of medications, difficulty accessing health care, and poor adherence seem to impact lupus outcomes and treatment response. In this article, the management of cSLE patients is updated. Regarding pathogenesis, a number of potential targets for drugs have been studied. However, most treatments in pediatric patients are off-label drugs with recommendations based on inadequately powered studies, therapeutic consensus guidelines, or case series. Management practices for cSLE patients include evaluations of disease activity and cumulative damage scores, routine non-live vaccinations, physical activity, and addressing mental health issues. Antimalarials and glucocorticoids are still the most common drugs used to treat cSLE, and hydroxychloroquine is recommended for nearly all cSLE patients. Disease-modifying antirheumatic drugs (DMARDs) should be standardized for each patient, based on disease flare and cSLE severity. Mycophenolate mofetil or intravenous cyclophosphamide is suggested as induction therapy for lupus nephritis classes III and IV. Calcineurin inhibitors (cyclosporine, tacrolimus, voclosporin) appear to be another good option for cSLE patients with lupus nephritis. Regarding B-cell-targeting biologic agents, rituximab may be used for refractory lupus nephritis patients in combination with another DMARD, and belimumab was recently approved by the US Food and Drug Administration for cSLE treatment in children aged > 5 years. New therapies targeting CD20, such as atacicept and telitacicept, seem to be promising drugs for SLE patients. Anti-interferon therapies (sifalimumab and anifrolumab) have shown beneficial results in phase II randomized control trials in adult SLE patients, as have some Janus kinase inhibitors, and these could be alternative treatments for pediatric patients with severe interferon-mediated inflammatory disease in the future. In addition, strict control of proteinuria and blood pressure is required in cSLE, especially with angiotensin-converting enzyme inhibitor and angiotensin receptor blocker use.

The PD-1/PD-L pathway in rheumatic diseases

BACKGROUND/PURPOSE

Autoimmune diseases are diseases in which the body produces an abnormal immune response to self-antigens and damages its own tissues. Programmed death-1 (PD-1) and its ligands (PD-Ls) have been discovered to be important negative regulators of the immune system, playing crucial roles in autoimmunity.

METHODS

We analyzed the existing scientific literature dealing with this issue. In this review, the PD-1/PD-L pathway in the genetic susceptibility to and pathogenesis of rheumatic diseases is discussed. The PD-1/PD-L pathway might be helpful for diagnosing, evaluating the disease activity of and treating rheumatic diseases.

RESULTS

PD-1/PD-L gene polymorphisms are associated with a genetic predisposition to rheumatic disorders, which can provide reference information for diagnosis and disease activity. The conclusion of the crucial role of the PD-1/PD-L pathway in the pathogenesis of rheumatic diseases is consistent, but the details remain controversial. In some animal models, manipulating the PD-1/PD-L pathway could decrease disease severity. PD-1/PD-Ls may enable us to develop new therapeutics for patients with rheumatic diseases in the future.

CONCLUSION

The PD-1/PD-L pathway plays crucial roles in rheumatic disease. More work is needed to provide a better mechanistic understanding of the PD-1/PD-L pathway and to facilitate the precise therapeutic manipulation of this pathway.

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.

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

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

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

Background

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

Methods

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

Results

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

Conclusions

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