Efficacy and safety of low-dose IL-2 in the treatment of systemic lupus erythematosus: a randomised, double-blind, placebo-controlled trial

Psoriasis and Lupus Erythematosus-Similarities and Differences between Two Autoimmune Diseases

Systemic lupus erythematosus (SLE) and psoriasis (Ps) are two clinically distinct diseases with different pathogenesis. However, recent studies indicate some similarities in both clinical presentation and pathogenetic mechanisms. The coexistence of both entities is very uncommon and has not been fully elucidated. Thus, it remains a diagnostic and therapeutic challenge. In fact, drugs used in SLE can induce psoriatic lesions, whereas phototherapy effective in Ps is an important factor provoking skin lesions in patients with SLE. The aim of this work is to discuss in detail the common pathogenetic elements and the therapeutic options effective in both diseases.

Low-dose Interleukin-2 Therapy: Fine-tuning Treg in Solid Organ Transplantation?

Regulatory T cells (Treg), a subset of CD4 + T cells, are potent regulators of immune reactions, which have been shown to be a promising therapeutic alternative to toxic immunosuppressive drugs. Data support the utility of Treg in managing immunopathologies, including solid organ transplant rejection, graft-versus-host disease, and autoimmune disorders. Notably, reports suggest that interleukin-2 (IL-2) is critical to survival of Treg, which constitutively express high levels of CD25, that is, the IL-2 receptor α-chain, and are exquisitely sensitive to IL-2, even at very low concentrations in contrast to effector T cells, which only upregulate IL-2 receptor α-chain on activation. This has led to the notion of using low doses of exogenous IL-2 therapeutically to modulate the immune system, specifically Treg numbers and function. Here, we summarize developments of clinical experience with low-dose IL-2 (LD-IL-2) as a therapeutic agent. So far, no clinical data are available to support the therapeutic use of LD-IL-2 therapy in the solid organ transplant setting. For the latter, fine-tuning by biotechnological approaches may be needed because of the narrow therapeutic window and off-target effects of LD-IL-2 therapy and so to realize the therapeutic potential of this molecule.

B- and T-Lymphocyte Attenuator in Systemic Lupus Erythematosus Disease Pathogenesis

B- and T-lymphocyte attenuator (BTLA; CD272) is an immunoglobulin superfamily member and part of a family of checkpoint inhibitory receptors that negatively regulate immune cell activation. The natural ligand for BTLA is herpes virus entry mediator (HVEM; TNFRSF14), and binding of HVEM to BTLA leads to attenuation of lymphocyte activation. In this study, we evaluated the role of BTLA and HVEM expression in the pathogenesis of systemic lupus erythematosus (SLE), a multisystem autoimmune disease. Peripheral blood mononuclear cells from healthy volunteers (N = 7) were evaluated by mass cytometry by time-of-flight to establish baseline expression of BTLA and HVEM on human lymphocytes compared with patients with SLE during a self-reported flare (N = 5). High levels of BTLA protein were observed on B cells, CD4+, and CD8+ T cells, and plasmacytoid dendritic cells in healthy participants. HVEM protein levels were lower in patients with SLE compared with healthy participants, while BTLA levels were similar between SLE and healthy groups. Correlations of BTLA-HVEM hub genes' expression with patient and disease characteristics were also analyzed using whole blood gene expression data from patients with SLE (N = 1,760) and compared with healthy participants (N = 60). HVEM, being one of the SLE-associated genes, showed an exceptionally strong negative association with disease activity. Several other genes in the BTLA-HVEM signaling network were strongly (negative or positive) correlated, while BTLA had a low association with disease activity. Collectively, these data provide a clinical rationale for targeting BTLA with an agonist in SLE patients with low HVEM expression.

Autoimmune diseases and atherosclerotic cardiovascular disease

Autoimmune diseases are associated with a dramatically increased risk of atherosclerotic cardiovascular disease and its clinical manifestations. The increased risk is consistent with the notion that atherogenesis is modulated by both protective and disease-promoting immune mechanisms. Notably, traditional cardiovascular risk factors such as dyslipidaemia and hypertension alone do not explain the increased risk of cardiovascular disease associated with autoimmune diseases. Several mechanisms have been implicated in mediating the autoimmunity-associated cardiovascular risk, either directly or by modulating the effect of other risk factors in a complex interplay. Aberrant leukocyte function and pro-inflammatory cytokines are central to both disease entities, resulting in vascular dysfunction, impaired resolution of inflammation and promotion of chronic inflammation. Similarly, loss of tolerance to self-antigens and the generation of autoantibodies are key features of autoimmunity but are also implicated in the maladaptive inflammatory response during atherosclerotic cardiovascular disease. Therefore, immunomodulatory therapies are potential efficacious interventions to directly reduce the risk of cardiovascular disease, and biomarkers of autoimmune disease activity could be relevant tools to stratify patients with autoimmunity according to their cardiovascular risk. In this Review, we discuss the pathophysiological aspects of the increased cardiovascular risk associated with autoimmunity and highlight the many open questions that need to be answered to develop novel therapies that specifically address this unmet clinical need.

Peroxynitrite reduces Treg cell expansion and function by mediating IL-2R nitration and aggravates multiple sclerosis pathogenesis: One sentence summary: Peroxynitrite-mediated Treg IL-2R nitration impacts on multiple sclerosis

T-helper 17 cells and regulatory T cells (Treg) are critical regulators in the pathogenesis of multiple sclerosis (MS) but the factors affecting Treg/Th17 balance remains largely unknown. Redox balance is crucial to maintaining immune homeostasis and reducing the severity of MS but the underlying mechanisms are unclear yet. Herein, we tested the hypothesis that peroxynitrite, a representative molecule of reactive nitrogen species (RNS), could inhibit peripheral Treg cells, disrupt Treg/Th17 balance and aggravate MS pathology by inducing nitration of interleukin-2 receptor (IL-2R) and down-regulating RAS/JNK-AP-1 signalling pathway. Experimental autoimmune encephalomyelitis (EAE) mouse model and serum samples of MS patients were used in the study. We found that the increases of 3-nitrotyrosine and IL-2R nitration in Treg cells were coincided with disease severity in the active EAE mice. Mechanistically, peroxynitrite-induced IL-2R nitration down-regulated RAS/JNK signalling pathway, subsequently impairing peripheral Treg expansion and function, increasing Teff infiltration into the central nerve system (CNS), aggravating demyelination and neurological deficits in the EAE mice. Those changes were abolished by peroxynitrite decomposition catalyst (PDC) treatment. Furthermore, transplantation of the PDC-treated-autologous Treg cells from donor EAE mice significantly decreased Th17 cells in both axillary lymph nodes and lumbar spinal cord, and ameliorated the neuropathology of the recipient EAE mice. Those results suggest that peroxynitrite could disrupt peripheral Treg/Th17 balance, and aggravate neuroinflammation and neurological deficit in active EAE/MS pathogenesis. The underlying mechanisms are related to induce the nitration of IL-2R and inhibit the RAS/JNK-AP-1 signalling pathway in Treg cells. The study highlights that targeting peroxynitrite-mediated peripheral IL-2R nitration in Treg cells could be a novel therapeutic strategy to restore Treg/Th17 balance and ameliorate MS/EAE pathogenesis. The study provides valuable insights into potential role of peripheral redox balance in maintaining CNS immune homeostasis.

New and emerging therapies for systemic lupus erythematosus

Systemic Lupus Erythematosus (SLE) and lupus nephritis treatment is still based on non-specific immune suppression despite the first biological therapy for the disease having been approved more than a decade ago. Intense basic and translational research has uncovered a multitude of pathways that are actively being evaluated as treatment targets in SLE and lupus nephritis, with two new medications receiving FDA approval in the last 3 years. Herein we provide an overview of targeted therapies for SLE including medications targeting the B lymphocyte compartment, intracellular signaling, co-stimulation, and finally the interferons and other cytokines.

Systemic lupus erythematosus therapeutic strategy: From immunotherapy to gut microbiota modulation

Systemic lupus erythematosus (SLE) is characterized by a systemic dysfunction of the innate and adaptive immune systems, leading to an attack on healthy tissues of the body. During the development of SLE, pathogenic features, such as the formation of autoantibodies to self-nuclear antigens, caused tissue damage including necrosis and fibrosis, with an increased expression of type Ⅰ interferon (IFN) regulated genes. Treatment of lupus with immunosuppressants and glucocorticoids, which are used as the standard therapy, is not effective enough and causes side effects. As an alternative, more effective immunotherapies have been developed, including monoclonal and bispecific antibodies that target B cells, T cells, co-stimulatory molecules, cytokines or their receptors, and signaling molecules. Encouraging results have been observed in clinical trials with some of these therapies. Furthermore, a chimeric antigen receptor T cells (CAR-T) therapy has emerged as the most effective, safe, and promising treatment option for SLE, as demonstrated by successful pilot studies. Additionally, emerging evidence suggests that gut microbiota dysbiosis may play a significant role in the severity of SLE, and the use of methods to normalize the gut microbiota, particularly fecal microbiota transplantation (FMT), opens up new opportunities for effective treatment of SLE.

Causal association of plasma circulating metabolites with nephritis: a Mendelian randomization study

Background

Nephritis is a pivotal catalyst in chronic kidney disease (CKD) progression. Although epidemiological studies have explored the impact of plasma circulating metabolites and drugs on nephritis, few have harnessed genetic methodologies to establish causal relationships.

Methods

Through Mendelian randomization (MR) in two substantial cohorts, spanning large sample sizes, we evaluated over 100 plasma circulating metabolites and 263 drugs to discern their causal effects on nephritis risk. The primary analytical tool was the inverse variance weighted (IVW) analysis. Our bioinformatic scrutiny of GSE115857 (IgA nephropathy, 86 samples) and GSE72326 (lupus nephritis, 238 samples) unveiled anomalies in lipid metabolism and immunological characteristics in nephritis. Thorough sensitivity analyses (MR-Egger, MR-PRESSO, leave-one-out analysis) were undertaken to verify the instrumental variables' (IVs) assumptions.

Results

Unique lipoprotein-related molecules established causal links with diverse nephritis subtypes. Notably, docosahexaenoic acid (DHA) emerged as a protective factor for acute tubulointerstitial nephritis (ATIN) (OR1 = 0.84, [95% CI 0.78-0.90], p1 = 0.013; OR2 = 0.89, [95% CI 0.82-0.97], p2 = 0.007). Conversely, multivitamin supplementation minus minerals notably increased the risk of ATIN (OR = 31.25, [95% CI 9.23-105.85], p = 0.004). Reduced α-linolenic acid (ALA) levels due to lipid-lowering drugs were linked to both ATIN (OR = 4.88, [95% CI 3.52-6.77], p < 0.001) and tubulointerstitial nephritis (TIN) (OR = 7.52, [95% CI 2.78-20.30], p = 0.042). While the non-renal drug indivina showed promise for TIN treatment, the use of digoxin, hydroxocobalamin, and liothyronine elevated the risk of chronic tubulointerstitial nephritis (CTIN). Transcriptome analysis affirmed that anomalous lipid metabolism and immune infiltration are characteristic of IgA nephropathy and lupus nephritis. The robustness of these causal links was reinforced by sensitivity analyses and leave-one-out tests, indicating no signs of pleiotropy.

Conclusion

Dyslipidemia significantly contributes to nephritis development. Strategies aimed at reducing plasma low-density lipoprotein levels or ALA supplementation may enhance the efficacy of existing lipid-lowering drug regimens for nephritis treatment. Renal functional status should also be judiciously considered with regard to the use of nonrenal medications.

Low-dose IL-2 therapy in autoimmune diseases: An update review

Regulatory T (Treg) cells are essential for maintaining self-immune tolerance. Reduced numbers or functions of Treg cells have been involved in the pathogenesis of various autoimmune diseases and allograft rejection. Therefore, the approaches that increase the pool or suppressive function of Treg cells in vivo could be a general strategy to treat different autoimmune diseases and allograft rejection. Interleukin-2 (IL-2) is essential for the development, survival, maintenance, and function of Treg cells, constitutively expressing the high-affinity receptor of IL-2 and sensitive response to IL-2 in vivo. And low-dose IL-2 therapy in vivo could restore the imbalance between autoimmune response and self-tolerance toward self-tolerance via promoting Treg cell expansion and inhibiting follicular helper T (Tfh) and IL-17-producing helper T (Th17) cell differentiation. Currently, low-dose IL-2 treatment is receiving extensive attention in autoimmune disease and transplantation treatment. In this review, we summarize the biology of IL-2/IL-2 receptor, the mechanisms of low-dose IL-2 therapy in autoimmune diseases, the application in the progress of different autoimmune diseases, including Systemic Lupus Erythematosus (SLE), Type 1 Diabetes (T1D), Rheumatoid Arthritis (RA), Autoimmune Hepatitis (AIH), Alopecia Areata (AA), Immune Thrombocytopenia (ITP) and Chronic graft-versus-host-disease (GVHD). We also discuss the future directions to optimize low-dose IL-2 treatments.

Concomitant use of interleukin-2 and tacrolimus suppresses follicular helper T cell proportion and exerts therapeutic effect against lupus nephritis in systemic lupus erythematosus-like chronic graft versus host disease

Introduction

Defective interleukin-2 (IL-2) production contributes to immune system imbalance in patients with systemic erythematosus lupus (SLE). Recent clinical studies suggested that low-dose IL-2 treatment is beneficial for SLE and the therapeutic effect is associated with regulatory T cell (Treg) expansion. Pharmacological calcineurin inhibition induces a reduction in the number of Tregs because they require stimulation of T cell receptor signaling and IL-2 for optimal proliferation. However, the activation of T cell receptor signaling is partially dispensable for the expansion of Tregs, but not for that of conventional T cells if IL-2 is present.

Aim

We examined whether addition of IL-2 restores the Treg proportion even with concurrent use of a calcineurin inhibitor and if the follicular helper T cell (Tfh) proportion is reduced in an SLE-like murine chronic graft versus host disease model.

Methods

Using a parent-into-F1 model, we investigated the effect of IL-2 plus tacrolimus on Treg and Tfh proportions and the therapeutic effect.

Results

Treatment with a combination of IL-2 and tacrolimus significantly delayed the initiation of proteinuria and decreased the urinary protein concentration, whereas tacrolimus or IL-2 monotherapy did not significantly attenuate proteinuria. Phosphorylation of signal transducer and activator of transcription 3, a positive regulator of Tfh differentiation, was reduced by combination treatment, whereas phosphorylation of signal transducer and activator of transcription 5, a negative regulator, was not reduced.

Conclusion

Addition of calcineurin inhibitors as adjunct agents may be beneficial for IL-2-based treatment of lupus nephritis.

The universal effects of low-dose interleukin-2 across 13 autoimmune diseases in a basket clinical trial

BACKGROUND

A Tregs insufficiency is central to autoimmune and inflammatory diseases pathophysiology and low dose interleukin-2 (IL-2LD) can specifically activate Tregs.

OBJECTIVE

To assess IL-2LD therapeutic potential and select diseases for further clinical development, we performed an open-label, phase 2a, disease-finding, "basket trial" involving patients with one of 13 different autoimmune diseases.

METHODS

81 patients treated with IL-2LD (1 million IU/day) for 5 days, followed by fortnightly injections. The first 48 patients received diluted Proleukin®, while the subsequent 33 received ready-to-use ILT-101®. The primary endpoint was the change in Tregs at day-8 compared to baseline. Key secondary endpoints included clinical efficacy assessments using the Clinical Global Impression (CGI) scale, disease-specific scores, and EuroQL-5D-5L.

RESULTS

Our study unveiled a universal and significant expansion and activation of Tregs, without concomitant Teffs activation, across all 13 autoimmune diseases. Both Proleukin® and ready-to-use ILT-101® demonstrated identical effects on Tregs. CGI scores reflecting activity, severity, and efficacy were significantly reduced in the overall patient population. Disease-specific clinical scores improved in five of the six disease cohorts with at least six patients, namely ankylosing spondylitis, systemic lupus erythematosus, Behçet's disease, Sjögren's syndrome, and systemic sclerosis. Urticaria was the only severe adverse event related to treatment.

CONCLUSION

IL-2LD was well-tolerated, exhibiting specific Treg activation and clinical improvements across the 13 autoimmune diseases.

CLINICAL IMPLICATION

Tregs stimulation by IL-2LD is a promising therapeutic strategy and IL-2LD holds considerable promise for integration into combinatorial therapeutic approaches.

An Updated Review of Interleukin-2 Therapy in Cancer and Autoimmune Diseases

Interleukin-2 (IL-2) is a cytokine that acts in dual and paradoxical ways in the immunotherapy of cancers and autoimmune diseases. Numerous clinical trial studies have shown that the use of different doses of this cytokine in various autoimmune diseases, transplantations, and cancers has resulted in therapeutic success. However, side effects of varying severity have been observed in patients. In recent years, to prevent these side effects, IL-2 has been engineered to bind more specifically to its receptors on the cell surface, decreasing IL-2 toxicities in patients. In this review article, we focus on some recent clinical trial studies and analyze them to determine the appropriate dose of IL-2 drug with the least toxicities. In addition, we discuss the engineering performed on IL-2, which shows that engineered IL-2 increases the specificity function of IL-2 and decreases its adverse effects.

A CD25-biased interleukin-2 for autoimmune therapy engineered via a semi-synthetic organism

BACKGROUND

Natural cytokines are poorly suited as therapeutics for systemic administration due to suboptimal pharmacological and pharmacokinetic (PK) properties. Recombinant human interleukin-2 (rhIL-2) has shown promise for treatment of autoimmune (AI) disorders yet exhibits short systemic half-life and opposing immune responses that negate an appropriate therapeutic index.

METHODS

A semi-synthetic microbial technology platform was used to engineer a site-specifically pegylated form of rhIL-2 with enhanced PK, specificity for induction of immune-suppressive regulatory CD4 + T cells (Tregs), and reduced stimulation of off-target effector T and NK cells. A library of rhIL-2 molecules was constructed with single site-specific, biorthogonal chemistry-compatible non-canonical amino acids installed near the interface where IL-2 engages its cognate receptor βγ (IL-2Rβγ) signaling complex. Biorthogonal site-specific pegylation and functional screening identified variants that retained engagement of the IL-2Rα chain with attenuated potency at the IL-2Rβγ complex.

RESULTS

Phenotypic screening in mouse identifies SAR444336 (SAR'336; formerly known as THOR-809), rhIL-2 pegylated at H16, as a potential development candidate that specifically expands peripheral CD4+ Tregs with upregulation of markers that correlate with their suppressive function including FoxP3, ICOS and Helios, yet minimally expands CD8 + T or NK cells. In non-human primate, administration of SAR'336 also induces dose-dependent expansion of Tregs and upregulated suppressive markers without significant expansion of CD8 + T or NK cells. SAR'336 administration reduces inflammation in a delayed-type hypersensitivity mouse model, potently suppressing CD4+ and CD8 + T cell proliferation.

CONCLUSION

SAR'336 is a specific Treg activator, supporting its further development for the treatment of AI diseases.

Novel and potential future therapeutic options in systemic autoimmune diseases

Autoimmune inflammation is caused by the loss of tolerance to specific self-antigens and can result in organ-specific or systemic disorders. Systemic autoimmune diseases affect a significant portion of the population with an increasing rate of incidence, which means that is essential to have effective therapies to control these chronic disorders. Unfortunately, several patients with systemic autoimmune diseases do not respond at all or just partially respond to available conventional synthetic disease-modifying antirheumatic drugs and targeted therapies. However, during the past few years, some new medications have been approved and can be used in real-life clinical settings. Meanwhile, several new candidates appeared and can offer promising novel treatment options in the future. Here, we summarize the newly available medications and the most encouraging drug candidates in the treatment of systemic lupus erythematosus, rheumatoid arthritis, Sjögren's disease, systemic sclerosis, systemic vasculitis, and autoimmune myositis.

Interleukin-2 signaling in the regulation of T cell biology in autoimmunity and cancer

Interleukin-2 (IL-2) is a critical cytokine for T cell peripheral tolerance and immunity. Here, we review how IL-2 interaction with the high-affinity IL-2 receptor (IL-2R) supports the development and homeostasis of regulatory T cells and contributes to the differentiation of helper, cytotoxic, and memory T cells. A critical element for each T cell population is the expression of CD25 (Il2rα), which heightens the receptor affinity for IL-2. Signaling through the high-affinity IL-2R also reinvigorates CD8+ exhausted T (Tex) cells in response to checkpoint blockade. We consider the molecular underpinnings reflecting how IL-2R signaling impacts these various T cell subsets and the implications for enhancing IL-2-dependent immunotherapy of autoimmunity, other inflammatory disorders, and cancer.

Th17 cells: A new target in kidney disease research

Type 17 T helper (Th17) cells, which are a subtype of CD4+ T helper cells, secrete pro-inflammatory cytokines such as IL-17A, IL-17F, IL-21, IL-22, and GM-CSF, which play crucial roles in immune defence and protection against fungal and extracellular pathogen invasion. However, dysfunction of Th17 cell immunity mediates inflammatory responses and exacerbates tissue damage. This pathological process initiated by Th17 cells is common in kidney diseases associated with renal injury, such as glomerulonephritis, lupus nephritis, IgA nephropathy, hypertensive nephropathy, diabetic kidney disease and acute kidney injury. Therefore, targeting Th17 cells to treat kidney diseases has been a hot topic in recent years. This article reviews the mechanisms of Th17 cell-mediated inflammation and autoimmune responses in kidney diseases and discusses the related clinical drugs that modulate Th17 cell fate in kidney disease treatment.

Comparison of Low-Dose Interleukin 2 Therapy in Conjunction With Standard Therapy in Patients With Systemic Lupus Erythematosus vs Rheumatoid Arthritis: A Systematic Review

This systematic review aims to compare the efficacy and safety of a novel immunotherapy with low-dose interleukin 2 (IL2) across two of the most prevalent autoimmune diseases i.e. systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). Contemporary therapeutic practices have not been able to achieve complete remission from these autoimmune disorders. In contrast, low-dose IL2 has shown promise in achieving this therapeutic goal via inducing self-tolerance in patients with autoimmune diseases; however, due to variable irregularities among autoimmune processes of variable diseases, the benefit of low-dose IL2 could not be determined among different autoimmune diseases. Therefore, we conducted a study to compare low-dose IL2 therapy effects on SLE and RA. We systematically screened four databases: PubMed, Medical Literature Analysis and Retrieval System Online (MEDLINE), PubMed Central (PMC), and Google Scholar. Inclusion and exclusion criteria were implemented. Quality appraisal of studies chosen for the review was done using the Cochrane Risk-of-Bias (RoB) assessment tool for randomized controlled trials, and the Newcastle-Ottawa Scale (NOS) and JBI critical appraisal tool for non-randomized clinical trials. Information was gathered from seven articles: three randomized controlled trials and four non-randomized clinical trials. Our review concluded that low-dose IL2 therapy in conjunction with respective standard therapies for SLE and RA has a higher efficacy and safety profile as compared to standard therapy alone and the therapeutic effects were comparable in both SLE and RA patients treated with low-dose IL2; however, this novel intervention does not seem to have a significant corrective effect on the biomarkers of RA as it does for SLE biomarkers.

The effects of low-dose IL-2 on Th17/Treg cell imbalance in primary biliary cholangitis mouse models

BACKGROUND/AIMS

Primary biliary cholangitis (PBC) is a chronic cholestatic liver disease. The imbalance of Th17/Treg cells has been reported in PBC patients. Low-dose IL-2 can alleviate disease severity through modulating CD4 + T cell subsets in patients with autoimmune diseases. Hence, the present study aimed to examine the effects and mechanism of low-dose IL-2 in PBC mouse models.

METHODS

PBC models were induced in female C57BL/6 mice by two immunizations with 2OA-BSA at two-week intervals, and poly I: C every three days. PBC mouse models were divided into the IL-2 treated and untreated groups and low-dose IL-2 was injected at three different time points. Th17 and Tregs were analyzed by flow cytometry, and the related cytokines were analyzed by ELISA. Liver histopathology was examined by H&E and immunohistochemical staining.

RESULTS

Twelve weeks after modeling, the serum AMA was positive and the ALP was significantly increased in PBC mouse models (P<0.05). The pathology showed lymphocyte infiltration in the portal area, damage, and reactive proliferation of the small bile duct (P<0.05). The flow cytometric showed the imbalance of Th17/Treg cells in the liver of PBC mouse models, with decreased Treg cells, increased Th17 cells, and Th17/Treg ratio (P < 0.05). After the low-dose IL-2 intervention, biochemical index and liver pathologies showed improvement at 12 weeks. Besides, the imbalance of Th17 and Treg cells recovered. Public database mining showed that Th17 cell differentiation may contribute to poor response in PBC patients.

CONCLUSION

Low-dose IL-2 can significantly improve liver biochemistry and pathology by reversing the imbalance of Th17 and Treg cells, suggesting that it may be a potential therapeutic target for PBC.

Smith-specific regulatory T cells halt the progression of lupus nephritis

Antigen-specific regulatory T cells (Tregs) suppress pathogenic autoreactivity and are potential therapeutic candidates for autoimmune diseases such as systemic lupus erythematosus (SLE). Lupus nephritis is associated with autoreactivity to the Smith (Sm) autoantigen and the human leucocyte antigen (HLA)-DR15 haplotype; hence, we investigated the potential of Sm-specific Tregs (Sm-Tregs) to suppress disease. Here we identify a HLA-DR15 restricted immunodominant Sm T cell epitope using biophysical affinity binding assays, then identify high-affinity Sm-specific T cell receptors (TCRs) using high-throughput single-cell sequencing. Using lentiviral vectors, we transduce our lead Sm-specific TCR into Tregs derived from patients with SLE who are anti-Sm and HLA-DR15 positive. Compared with polyclonal mock-transduced Tregs, Sm-Tregs potently suppress Sm-specific pro-inflammatory responses in vitro and suppress disease progression in a humanized mouse model of lupus nephritis. These results show that Sm-Tregs are a promising therapy for SLE.

A State-of-the-Art Review on the Recent Advances of Mesenchymal Stem Cell Therapeutic Application in Systematic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease with an unknown etiology that has widespread clinical and immunological manifestations. Despite the increase in knowledge about the pathogenesis process and the increase in treatment options, however, the treatments fail in half of the cases. Therefore, there is still a need for research on new therapies. Mesenchymal stem cells (MSCs) are powerful regulators of the immune system and can reduce the symptoms of systemic lupus erythematosus. This study aimed to review the mechanisms of immune system modulation by MSCs and the role of these cells in the treatment of SLE. MSCs suppress T lymphocytes through various mechanisms, including the production of transforming growth factor-beta (TGF-B), prostaglandin E2 (PGE2), nitric oxide (NO), and indolamine 2 and 3-oxygenase (IDO). In addition, MSCs inhibit the production of their autoantibodies by inhibiting the differentiation of lymphocytes. The production of autoantibodies against nuclear antigens is an important feature of SLE. On the other hand, MSCs inhibit antigen delivery by antigen-presenting cells (APCs) to T lymphocytes. Studies in animal models have shown the effectiveness of these cells in treating SLE. However, few studies have been performed on the effectiveness of this treatment in humans. It can be expected that new treatment strategies for SLE will be introduced in the future, given the promising results of MSCs application.

Efficacy, Safety and the Lymphocyte Subset Changes of Low-Dose IL-2 in Patients with Autoimmune Rheumatic Diseases: A Systematic Review and Meta-Analysis

INTRODUCTION

Current therapies for autoimmune rheumatic diseases (ARDs) have limited efficacy in certain patients, highlighting the need for the development of novel treatment approaches. This meta-analysis aims to assess the efficacy and safety of low-dose interleukin-2 (LD-IL-2) and evaluate the alterations in lymphocyte subsets in various rheumatic diseases following administration of different dosages of LD-IL-2.

METHODS

A comprehensive search was conducted in PubMed, Web of Science, the Cochrane Library, Embase databases and CNKI to identify relevant studies. A total of 31 trials were included in this meta-analysis. The review protocols were registered on PROSPERO (CRD42022318916), and the study followed the PRISMA guidelines.

RESULTS

Following LD-IL-2 treatment, patients with ARDs exhibited a significant increase in the number of Th17 cells and Tregs compared to their pre-treatment levels [standardized mean difference (SMD) = 0.50, 95% confidence interval (CI) (0.33, 0.67), P < 0.001; SMD = 1.13, 95% CI (0.97, 1.29), P < 0.001]. Moreover, the Th17/Tregs ratio showed a significant decrease [SMD = - 0.54, 95% CI (- 0.64, - 0.45), P < 0.001]. In patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), LD-IL-2 injection led to a significant increase in Treg numbers, and the Th17/Tregs ratio and disease activity scores, including Disease Activity Score-28 joints (DAS28), Systemic Lupus Erythematosus Disease Activity Index (SELENA-SLEDAI) and Cutaneous Dermatomyositis Disease Area and Severity Index (CDASI), were all significantly reduced. No serious adverse events were reported in any of the included studies. Additionally, 54.8% of patients with lupus nephritis achieved distinct clinical remission following LD-IL-2 treatment. Injection site reactions and fever were the most common side effects of LD-IL-2, occurring in 33.1% and 14.4% of patients, respectively.

CONCLUSION

LD-IL-2 treatment showed promise and was well tolerated in the management of ARDs, as it effectively promoted the proliferation and functional recovery of Tregs.

TRIAL REGISTRATION

Retrospectively registered (CRD42022318916, 21/04/2022).

[Immunopathogenesis of systemic lupus erythematosus]

Insights into the immunopathogenesis of systemic lupus erythematosus (SLE) help to understand the complex disease patterns and to develop new treatment strategies. The disease manifestations essentially result from autoantibodies, immune complexes and cytokines. Particularly the propensity towards developing various autoantibodies is central to the disease itself; autoantibody specificities lead to highly variable organ manifestations. This review article delineates the clinically relevant state of knowledge on SLE pathogenesis, with the goal to establish a model useful for clinical practice, which also helps to classify the novel therapeutic approaches.

Immunotherapy Strategy for Systemic Autoimmune Diseases: Betting on CAR-T Cells and Antibodies

Systemic autoimmune diseases (SAIDs), such as systemic lupus erythematosus (SLE), systemic sclerosis (SSc) and rheumatoid arthritis (RA), are fully related to the unregulated innate and adaptive immune systems involved in their pathogenesis. They have similar pathogenic characteristics, including the interferon signature, loss of tolerance to self-nuclear antigens, and enhanced tissue damage like necrosis and fibrosis. Glucocorticoids and immunosuppressants, which have limited specificity and are prone to tolerance, are used as the first-line therapy. A plethora of novel immunotherapies have been developed, including monoclonal and bispecific antibodies, and other biological agents to target cellular and soluble factors involved in disease pathogenesis, such as B cells, co-stimulatory molecules, cytokines or their receptors, and signaling molecules. Many of these have shown encouraging results in clinical trials. CAR-T cell therapy is considered the most promising technique for curing autoimmune diseases, with recent successes in the treatment of SLE and SSc. Here, we overview novel therapeutic approaches based on CAR-T cells and antibodies for targeting systemic autoimmune diseases.

Beyond FOXP3: a 20-year journey unravelling human regulatory T-cell heterogeneity

The initial idea of a distinct group of T-cells responsible for suppressing immune responses was first postulated half a century ago. However, it is only in the last three decades that we have identified what we now term regulatory T-cells (Tregs), and subsequently elucidated and crystallized our understanding of them. Human Tregs have emerged as essential to immune tolerance and the prevention of autoimmune diseases and are typically contemporaneously characterized by their CD3+CD4+CD25high CD127lowFOXP3+ phenotype. It is important to note that FOXP3+ Tregs exhibit substantial diversity in their origin, phenotypic characteristics, and function. Identifying reliable markers is crucial to the accurate identification, quantification, and assessment of Tregs in health and disease, as well as the enrichment and expansion of viable cells for adoptive cell therapy. In our comprehensive review, we address the contributions of various markers identified in the last two decades since the master transcriptional factor FOXP3 was identified in establishing and enriching purity, lineage stability, tissue homing and suppressive proficiency in CD4+ Tregs. Additionally, our review delves into recent breakthroughs in innovative Treg-based therapies, underscoring the significance of distinct markers in their therapeutic utilization. Understanding Treg subsets holds the key to effectively harnessing human Tregs for immunotherapeutic approaches.

Targeted therapies for lupus nephritis: Current perspectives and future directions

ABSTRACT

Lupus nephritis (LN), a severe manifestation of systemic lupus erythematosus, poses a substantial risk of progression to end-stage renal disease, with increased mortality. Conventional therapy for LN relies on broad-spectrum immunosuppressants such as glucocorticoids, mycophenolate mofetil, and calcineurin inhibitors. Although therapeutic regimens have evolved over the years, they have inherent limitations, including non-specific targeting, substantial adverse effects, high relapse rates, and prolonged maintenance and remission courses. These drawbacks underscore the need for targeted therapeutic strategies for LN. Recent advancements in our understanding of LN pathogenesis have led to the identification of novel therapeutic targets and the emergence of biological agents and small-molecule inhibitors with improved specificity and reduced toxicity. This review provides an overview of the current evidence on targeted therapies for LN, elucidates the biological mechanisms of responses and failure, highlights the challenges ahead, and outlines strategies for subsequent clinical trials and integrated immunomodulatory approaches.

Efficacy, safety and the lymphocyte subsets changes of low-dose IL-2 in patients with systemic lupus erythematosus: A systematic review and meta-analysis

INTRODUCTION

Existing therapies of systemic lupus erythematosus (SLE) are efficacious only in certain patients. Developing new treatment methods is urgent. This meta-analysis aimed to evaluate the efficacy and safety of low-dose IL-2 (LD-IL-2).

METHODS

According to published data from PubMed, Web of Science, Embase, ClinicalTrials.gov, MEDLINE, MEDLINE, Web of Knowledge, Cochrane Library, and FDA.gov, eight trials were included.

RESULTS

After the LD-IL-2 treatment, 54.8% of patients had distinct clinical remission. The SRI-4 response rates were 0.819 (95% confidence interval [CI]: 0.745-0.894), and the SELENA-SLEDAI scores were significantly decreased (SMD = -2.109, 95% CI: [-3.271, -0.947], p < .001). Besides, the proportions of CD4+ T (SMD = 0.614, 95% CI: [0.250, 0.979], p = .001) and Treg cells (SMD = 1.096, 95% CI: [0.544, 1.649], p < .001) were increased dramatically after LD-IL-2 treatment, while there were no statistical differences in the proportions of CD8+ T cells, Th1 cells, Th2 cells, and Th17 cells (p > .05). Besides, the proportions of Th17 (SMD = 1.121, 95% CI: [0.709, 1.533], p < .001) and Treg (SMD = 0.655, 95% CI: [0.273, 1.038], p = .001) were significantly increased after receiving subcutaneously 0.5 million IU of LD-IL-2 treatment per day for 5 days, but there were no statistical differences in the proportions of Treg after receiving 1 million IU every other day subcutaneously of LD-IL-2 treatment. Injection site reaction and fever were common side effects of IL-2, which occurred in 33.1% and 14.4% of patients. No serious adverse events were reported.

CONCLUSION

LD-IL-2 was promising and well-tolerated in treating SLE, which could promote Treg's proliferation and functional recovery. Injecting 0.5 million IU of IL-2 daily can better induce the differentiation of Treg cells and maintain immune homeostasis than injecting 1 million IU every other day.

Th1-related transcription factors and cytokines in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an inflammatory disorder related to immunity dysfunction. The Th1 cell family including Th1 cells, transcription factor T-bet, and related cytokines IFNγ, TNFα, IL-2, IL-18, TGF-β, and IL-12 have been widely discussed in autoimmunity, such as SLE. In this review, we will comprehensively discuss the expression profile of the Th1 cell family in both SLE patients and animal models and clarify how the family members are involved in lupus development. Interestingly, T-bet-related age-associated B cells (ABCs) and low-dose IL-2 treatment in lupus were emergently discussed as well. Collection of the evidence will better understand the roles of the Th1 cell family in lupus pathogenesis, especially targeting IL-2 in lupus.

An IL-2 mutein increases IL-10 and CTLA-4-dependent suppression of dendritic cells by regulatory T cells

Interleukin-2 (IL-2) variants with increased CD25 dependence that selectively expand Foxp3+ regulatory T (TR) cells are in clinical trials for treating inflammatory diseases. Using an Fc-fused IL-2 mutein (Fc.IL-2 mutein) we developed that prevents diabetes in non-obese diabetic (NOD) mice, we show that Fc.IL-2 mutein induced an activated TR population with elevated proliferation, a transcriptional program associated with Stat5- and TCR-dependent gene modules, and high IL-10 and CTLA-4 expression. Increased IL-10 signaling limited surface MHC class II upregulation during conventional dendritic cell (cDC) maturation, while increased CTLA-4-dependent transendocytosis led to the transfer of CD80 and CD86 costimulatory ligands from maturing cDCs to TR cells. In NOD mice, Fc.IL-2 mutein treatment promoted the suppression of cDCs in the inflamed pancreas and pancreatic lymph nodes resulting in T cell anergy. Thus, IL-2 mutein-expanded TR cells have enhanced functional properties and restrict cDC function, offering promise for targeted immunotherapy use in autoimmune disease.

Why Treg should be the focus of cancer immunotherapy: The latest thought

Regulatory T cells are a subgroup of T cells with immunomodulatory functions. Different from most cytotoxic T cells and helper T cells, they play a supporting role in the immune system. What's more, regulatory T cells often play an immunosuppressive role, which mainly plays a role in maintaining the stability of the immune system and regulating the immune response in the body. However, recent studies have shown that not only playing a role in autoimmune diseases, organ transplantation, and other aspects, regulatory T cells can also play a role in the immune escape of tumors in the body, through various mechanisms to help tumor cells escape from the demic immune system, weakening the anti-cancer effect in the body. For a better understanding of the role that regulatory T cells can play in cancer, and to be able to use regulatory T cells for tumor immunotherapy more quickly. This review focuses on the research progress of various mechanisms of regulatory T cells in the tumor environment, the related research of tumor cells acting on regulatory T cells, and the existing various therapeutic methods acting on regulatory T cells.

Low-dose Interleukin-2 For Psoriasis Therapy Based on the Regulation of Th17/Treg Cell Balance in Peripheral Blood

The imbalance between regulatory T (Treg) cells and efficient T cells plays an important role in psoriasis. Low-dose interleukin (IL)-2 can preferentially activate Treg cells and ameliorate the imbalance of Treg/efficient T cells. This study focused on the status of circulating CD4+ T subsets and the clinical efficacy of low-dose IL-2 therapies in psoriasis. This retrospective study included peripheral blood samples obtained from 45 psoriatic patients and 40 healthy controls. The 45 psoriatic patients received three cycles of subcutaneous low-dose IL-2 treatment (0.5 million IU/day for 2 weeks) combined with conventional therapies. Inflammatory indices, CD4+ T-lymphocyte subsets, and cytokines were measured in all patients before and after treatment. The percentage of Treg cells was dramatically decreased in the psoriasis group compared to the healthy group, and the percentage of Treg cells negatively correlated with the disease indices and the Psoriasis Area and Severity Index (PASI) (P < 0.001). The Th17/Treg ratio was significantly increased in the psoriasis group compared to the healthy group, and the Th17/Treg ratio positively correlated with disease indices and PASI (P < 0.001). Low-dose IL-2 treatment significantly amplified the percentage of Treg cells and restored the Th17 and Treg immune balance in psoriasis (P < 0.001). Low-dose IL-2 combination therapy effectively improved the clinical manifestations of psoriasis but decreased the inflammatory indicators of the disease activity, with no apparent side effects. Thus, low-dose IL-2 provides a new strategy for the treatment of psoriasis.

Identification and Characterization of CD8+ CD27+ CXCR3- T Cell Dysregulation and Progression-Associated Biomarkers in Systemic Lupus Erythematosus

Systemic Lupus Erythematosus (SLE) etiopathogenesis highlights the contributions of overproduction of CD4+ T cells and loss of immune tolerance. However, the involvement of CD8+ T cells in SLE pathology and disease progression remains unclear. Here, the comprehensive immune cell dysregulation in total 263 clinical peripheral blood samples composed of active SLE (aSLE), remission SLE (rSLE) and healthy controls (HCs) is investigated via mass cytometry, flow cytometry and single-cell RNA sequencing. This is observed that CD8+ CD27+ CXCR3- T cells are increased in rSLE compare to aSLE. Meanwhile, the effector function of CD8+ CD27+ CXCR3- T cells are overactive in aSLE compare to HCs and rSLE, and are positively associated with clinical SLE activity. In addition, the response of peripheral blood mononuclear cells (PBMCs) is monitored to interleukin-2 stimulation in aSLE and rSLE to construct dynamic network biomarker (DNB) model. It is demonstrated that DNB score-related parameters can faithfully predict the remission of aSLE and the flares of rSLE. The abundance and functional dysregulation of CD8+ CD27+ CXCR3- T cells can be potential biomarkers for SLE prognosis and concomitant diagnosis. The DNB score with accurate prediction to SLE disease progression can provide clinical treatment suggestions especially for drug dosage determination.

New and future therapies: Changes in the therapeutic armamentarium for SLE

Following better understanding of molecular pathways involved in the pathogenesis of Systemic lupus erythematosus (SLE), pharmaceutical companies have been investigating new targeted drugs for SLE. The purpose of this scoping review is to provide an updated view of the most promising targeted therapies currently in clinical development or recently approved for SLE treatment as well as of the most promising potential future therapeutic strategies in SLE. In the past several years, two new drugs have been developed for lupus treatment along with an extended indication for belimumab. Anifrolumab, the anti-interferon medication, to treat non-renal lupus; voclosporin, a calcineurin inhibitor, for the treatment of lupus nephritis; and belimumab for lupus nephritis. More than 90 investigational drugs are currently in clinical development for SLE treatment, with various targets including inflammatory cytokines and their receptors, intracellular signaling, B cells or plasma cells, co-stimulation molecules, complement fractions, T cells, plasmacytoid dendritic cells as well as various other immunological targets of interest. Researchers are also actively engaged in the development of new therapeutic strategies, including the use of monoclonal antibodies in combination with bispecific monoclonal antibodies, nanobodies and nanoparticles, therapeutic vaccines, utilizing siRNA interference techniques, autologous hematopoietic stem-cell transplantation and Chimeric Antigens Receptor (CAR)-T cells. The therapeutic management and prognosis of SLE have profoundly evolved with changes in the therapeutic armamentarium. With the broad pipeline of targeted treatments in clinical development and new treatment strategies in the future, current challenges are transitioning from the availability of new drugs to the selection of the most appropriate strategy at the patient level.

Rapamycin nanoparticles increase the therapeutic window of engineered interleukin-2 and drive expansion of antigen-specific regulatory T cells for protection against autoimmune disease

Interleukin-2 (IL-2) therapies targeting the high affinity IL-2 receptor expressed on regulatory T cells (Tregs) have shown promising therapeutic benefit in autoimmune diseases through nonselective expansion of pre-existing Treg populations, but are potentially limited by the inability to induce antigen-specific Tregs, as well as by dose-limiting activation of effector immune cells in settings of inflammation. We recently developed biodegradable nanoparticles encapsulating rapamycin, called ImmTOR, which induce selective immune tolerance to co-administered antigens but do not increase total Treg numbers. Here we demonstrate that the combination of ImmTOR and an engineered Treg-selective IL-2 variant (termed IL-2 mutein) increases the number and durability of total Tregs, as well as inducing a profound synergistic increase in antigen-specific Tregs when combined with a target antigen. We demonstrate that the combination of ImmTOR and an IL-2 mutein leads to durable inhibition of antibody responses to co-administered AAV gene therapy capsid, even at sub-optimal doses of ImmTOR, and provides protection in autoimmune models of type 1 diabetes and primary biliary cholangitis. Importantly, ImmTOR also increases the therapeutic window of engineered IL-2 molecules by mitigating effector immune cell expansion and preventing exacerbation of disease in a model of graft-versus-host-disease. At the same time, IL-2 mutein shows potential for dose-sparing of ImmTOR. Overall, these results establish that the combination of ImmTOR and an IL-2 mutein show synergistic benefit on both safety and efficacy to provide durable antigen-specific immune tolerance to mitigate drug immunogenicity and to treat autoimmune diseases.

Biomarkers Associated with Drugs for the Treatment of Lupus Nephritis

The constant updating of lupus drug treatment guidelines has led to a question. How can the efficacy of treatment be more effectively monitored? Systemic lupus erythematosus (SLE) is a complex autoimmune disease that often presents clinically with multi-organ involvement, and approximately 30% of patients with SLE develop lupus nephritis (LN). Therefore, it is important to better track disease progression and drug efficacy. Now, kidney biopsy is still the gold standard for diagnosing and guiding the treatment of LN, but it is invasive and expensive. If simple, non-invasive and effective biomarkers can be found, drug intervention and prognosis can be better monitored and targeted. In this review, we focus on LN and explore biomarkers related to LN therapeutics, providing clinicians with more possibilities to track the therapeutic effect of drugs, improve treatment options and assess patient outcomes.

CD4+CD25+FOXP3+ regulatory T cells: a potential "armor" to shield "transplanted allografts" in the war against ischemia reperfusion injury

Despite the advances in therapeutic interventions, solid organ transplantation (SOT) remains the "gold standard" treatment for patients with end-stage organ failure. Recently, vascularized composite allotransplantation (VCA) has reemerged as a feasible treatment option for patients with complex composite tissue defects. In both SOT and VCA, ischemia reperfusion injury (IRI) is inevitable and is a predominant factor that can adversely affect transplant outcome by potentiating early graft dysfunction and/or graft rejection. Restoration of oxygenated blood supply to an organ which was previously hypoxic or ischemic for a period of time triggers cellular oxidative stress, production of both, pro-inflammatory cytokines and chemokines, infiltration of innate immune cells and amplifies adaptive alloimmune responses in the affected allograft. Currently, Food and Drug Administration (FDA) approved drugs for the treatment of IRI are unavailable, therefore an efficacious therapeutic modality to prevent, reduce and/or alleviate allograft damages caused by IRI induced inflammation is warranted to achieve the best-possible transplant outcome among recipients. The tolerogenic capacity of CD4+CD25+FOXP3+ regulatory T cells (Tregs), have been extensively studied in the context of transplant rejection, autoimmunity, and cancer. It was not until recently that Tregs have been recognized as a potential cell therapeutic candidate to be exploited for the prevention and/or treatment of IRI, owing to their immunomodulatory potential. Tregs can mitigate cellular oxidative stress, produce anti-inflammatory cytokines, promote wound healing, and tissue repair and prevent the infiltration of pro-inflammatory immune cells in injured tissues. By using strategic approaches to increase the number of Tregs and to promote targeted delivery, the outcome of SOT and VCA can be improved. This review focuses on two sections: (a) the therapeutic potential of Tregs in preventing and mitigating IRI in the context of SOT and VCA and (b) novel strategies on how Tregs could be utilized for the prevention and/or treatment of IRI.

Occurrence and localization of FOXP3 + cells in kidney biopsies in lupus nephritis and ANCA-associated vasculitis

The study aims to increase the understanding regarding the role of regulatory T cells (Tregs) in lupus nephritis (LN) and ANCA-associated vasculitis (AAV) by comparing their localization in renal tissue and changes following immunosuppressive therapy. Kidney biopsies from 12 patients with LN and 7 patients with AAV were examined. Kidney biopsies had been performed both at active disease and following immunosuppressive treatment. Clinical data was collected at both biopsy occasions. Expression of Forkhead Box P 3 (Foxp3) in renal tissue was assessed by immunohistochemistry. An arbitrary scale was used to estimate the number of Foxp3+ cells. In LN, 8/12 (67%) had positive tissue staining for Foxp3 at baseline, most pronounced in inflammatory infiltrates, but also interstitially and in a peri-glomerular pattern. At second biopsies, after immunosuppressive treatment, 4/12 (33%) still had detectable Foxp3+ cells, found in persisting inflammatory infiltrates and some in the interstitium. Patients with a good clinical response to treatment had high grade of Foxp3+ cells in first biopsies. In AAV, only 2/7 (29%) had positive staining for Foxp3 at baseline, in inflammatory infiltrates and to a lesser extent in the interstitium, despite large areas of inflammatory infiltrates in all patients. At follow-up, 2/7 (29%) biopsies were positive for Foxp3. Our data show a higher presence of Foxp3+ cells in renal tissue from LN patients compared to AAV, suggesting that Tregs may be differently involved in the control of inflammatory mechanisms in these diseases. These findings could have further implication for therapeutic approaches aiming at restoring the immunological tolerance. Key Points • Foxp3+-cells are present in larger amount in renal tissue in lupus nephritis vs. ANCA-associated vasculitis. • Our data suggest that Foxp3+ regulatory T cells are involved in the control of inflammatory processes in lupus nephritis.

Strategies to therapeutically modulate cytokine action

Cytokines are secreted or membrane-presented molecules that mediate broad cellular functions, including development, differentiation, growth and survival. Accordingly, the regulation of cytokine activity is extraordinarily important both physiologically and pathologically. Cytokine and/or cytokine receptor engineering is being widely investigated to safely and effectively modulate cytokine activity for therapeutic benefit. IL-2 in particular has been extensively engineered, to create IL-2 variants that differentially exhibit activities on regulatory T cells to potentially treat autoimmune disease versus effector T cells to augment antitumour effects. Additionally, engineering approaches are being applied to many other cytokines such as IL-10, interferons and IL-1 family cytokines, given their immunosuppressive and/or antiviral and anticancer effects. In modulating the actions of cytokines, the strategies used have been broad, including altering affinities of cytokines for their receptors, prolonging cytokine half-lives in vivo and fine-tuning cytokine actions. The field is rapidly expanding, with extensive efforts to create improved therapeutics for a range of diseases.

Autoimmune uveitis in Behçet's disease and Vogt-Koyanagi-Harada disease differ in tissue immune infiltration and T cell clonality

Objectives

Non-infectious uveitis is often secondary to systemic autoimmune diseases, with Behçet's disease (BD) and Vogt-Koyanagi-Harada disease (VKHD) as the two most common causes. Uveitis in BD and VKHD can show similar clinical manifestations, but the underlying immunopathogenesis remains unclear.

Methods

To understand immune landscapes in inflammatory eye tissues, we performed single-cell RNA paired with T cell receptor (TCR) sequencing of immune cell infiltrates in aqueous humour from six patients with BD (N = 3) and VKHD (N = 3) uveitis patients.

Results

Although T cells strongly infiltrated in both types of autoimmune uveitis, myeloid cells only significantly presented in BD uveitis but not in VKHD uveitis. Conversely, VKHD uveitis but not BD uveitis showed an overwhelming dominance by CD4+ T cells (> 80%) within the T cell population due to expansion of CD4+ T cell clusters with effector memory (Tem) phenotypes. Correspondingly, VKHD uveitis demonstrated a selective expansion of CD4+ T cell clones which were enriched in pro-inflammatory Granzyme H+ CD4+ Tem cluster and showed TCR and Th1 pathway activation. In contrast, BD uveitis showed a preferential expansion of CD8+ T cell clones in pro-inflammatory Granzyme H+ CD8+ Tem cluster, and pathway activation for cytoskeleton remodelling, cellular adhesion and cytotoxicity.

Conclusion

Single-cell analyses of ocular tissues reveal distinct landscapes of immune cell infiltration and T-cell clonal expansions between VKHD and BD uveitis. Preferential involvements of pro-inflammatory CD4+ Th1 cells in VKHD and cytotoxic CD8+ T cells in BD suggest a difference in disease immunopathogenesis and can guide precision disease management.

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.

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.

East-Asian lupus nephritis in the Hopkins Lupus Cohort

Background and Objective

East Asian systemic lupus erythematosus (SLE) is under represented in lupus cohorts outside of East Asia. We asked whether lupus nephritis was more common and more severe in East Asians than in other ethnicities in a large United States SLE cohort.

Methods

The Hopkins Lupus Cohort, a longitudinal cohort of 2802 patients (53.5% Caucasian, 39.2% African-American, 3.2% East Asian) was studied. The SLICC/ACR Damage Index was used to assess renal outcomes. Results: East Asian patients had the same prevalence of lupus nephritis as African-Americans and both were higher than Caucasians. East Asians were not significantly different in frequency of end stage kidney disease compared with African-Americans. East Asians were more likely than Caucasians to have anti-Sm, low C3 and low C4. East Asians were more likely than African-Americans to have low C3 and low C4.

Conclusion

East Asians living in the United States were more likely to have lupus nephritis than Caucasians. Poor outcomes such as end stage kidney disease occurred at an equal frequency in East Asians as in African-Americans. Lupus nephritis was both more frequent and more severe in East Asians than in African-Americans.

Regulatory T cells: a new therapeutic link for Sjögren syndrome?

Great advancements have been made in understanding the pathogenesis of SS, but there remain unmet needs for effective and targeted treatments. Glandular and extraglandular dysfunction in SS is associated with autoimmune lymphocytic infiltration that invades the epithelial structures of affected organs. Regulatory T (Treg) cells are a subset of CD4+ T lymphocytes that maintain self-tolerance during physiological conditions. Besides inhibiting excessive inflammation and autoimmune response by targeting various immune cell subsets and tissues, Treg cells have also been shown to promote tissue repair and regeneration in pathogenic milieus. The changes of quantity and function of Treg cells in various autoimmune and chronic inflammatory disorders have been reported, owing to their effects on immune regulation. Here we summarize the recent findings from murine models and clinical data about the dysfunction of Treg cells in SS pathogenesis and discuss the therapeutic strategies of direct or indirect targeting of Treg cells in SS. Understanding the current knowledge of Treg cells in the development of SS will be important to elucidate disease pathogenesis and may guide research for successful therapeutic intervention in this disease.

A randomized double-blind placebo-controlled trial of low-dose interleukin-2 in relapsing-remitting multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) is associated with regulatory T cells (Tregs) insufficiency while low-dose interleukin-2 (IL2LD) activates Tregs and reduces disease activity in autoimmune diseases.

METHODS

We aimed at addressing whether IL2LD improved Tregs from MS patients. MS-IL2 was a single-center double-blind phase-2 study. Thirty patients (mean [SD] age 36.8 years [8.3], 16 female) with relapsing-remitting MS with new MRI lesions within 6 months before inclusion were randomly assigned in a 1:1 ratio to placebo or IL-2 at 1 million IU, daily for 5 days and then fortnightly for 6 months. The primary endpoint was change in Tregs at day-5.

RESULTS

Unlike previous trials of IL2LD in more than 20 different autoimmune diseases, Tregs were not expanded at day-5 in IL2LD group, but only at day-15 (median [IQR] fold change from baseline: 1.26 [1.21-1.33] in IL2LD group; 1.01 [0.95-1.05] in placebo group, p < 0.001). At day-5, however, Tregs had acquired an activated phenotype (fold change of CD25 expression in Tregs: 2.17 [1.70-3.55] in IL2LD versus 0.97 [0.86-1.28] in placebo group, p < 0.0001). Regulator/effector T cells ratio remained elevated throughout treatment period in the IL2LD group (p < 0.001). Number of new active brain lesions and of relapses tended to be reduced in IL2LD treated patients, but the difference did not reach significance in this trial not powered to detect clinical efficacy.

CONCLUSION

The effect of IL2LD on Tregs in MS patients was modest and delayed, compared to other auto-immune diseases. This, together with findings that Tregs improve remyelination in MS models and recent reports of IL2LD efficacy in amyotrophic lateral sclerosis, warrants larger studies of IL2LD in MS, notably with increased dosages and/or modified modalities of administration.

TRIAL REGISTRATION INFORMATION

ClinicalTrials.gov: NCT02424396; EU Clinical trials Register: 2014-000088-42.

Real-world experience with low-dose IL-2 for children and young adults with refractory chronic graft-versus-host disease

The majority of patients with chronic graft-versus-host disease (cGVHD) are steroid refractory (SR), creating a need for safe and effective therapies. Subcutaneous low-dose interleukin-2 (LD IL-2), which preferentially expands CD4+ regulatory T cells (Tregs), has been evaluated in 5 clinical trials at our center with partial responses (PR) in ∼50% of adults and 82% of children by week 8. We now report additional real-world experience with LD IL-2 in 15 children and young adults. We conducted a retrospective chart review of patients with SR-cGVHD at our center who received LD IL-2 from August 2016 to July 2022 not on a research trial. The median age at start of LD IL-2 was 10.4 years (range, 1.2-23.2 years) at a median of 234 days from cGVHD diagnosis (range, 11-542 days). Patients had a median of 2.5 (range, 1-3) active organs at LD IL-2 start and received a median of 3 (range, 1-5) prior therapies. The median duration of LD IL-2 therapy was 462 days (range, 8-1489 days). Most patients received 1 × 106 IU/m2 per day. There were no serious adverse effects. The overall response rate in 13 patients who received >4 weeks of therapy was 85% (complete response, n = 5; PR, n = 6) with responses in diverse organs. Most patients significantly weaned corticosteroids. Tregs preferentially expanded with a median peak fold increase of 2.8 in the ratio of Tregs to CD4+ conventional T cells (range, 2.0-19.8) by 8 weeks on therapy. LD IL-2 is a well-tolerated, steroid-sparing agent with a high response rate in children and young adults with SR-cGVHD.

Endocrine-disrupting chemicals and autoimmune diseases

Endocrine-disrupting chemicals (EDCs) widely exist in people's production and life which have great potential to damage human and animal health. Over the past few decades, growing attention has been paid to the impact of EDCs on human health, as well as immune system. So far, researchers have proved that EDCs (such as bisphenol A (BPA), phthalate, tetrachlorodibenzodioxin (TCDD), etc.) affect human immune function and promotes the occurrence and development of autoimmune diseases (ADs). Therefore, in order to better understand how EDCs affect ADs, we summarized the current knowledge about the impact of EDCs on ADs, and elaborated the potential mechanism of the impact of EDCs on ADs in this review.

CD56bright natural killer cells preferentially kill proliferating CD4+ T cells

Human CD56br natural killer (NK) cells represent a small subset of CD56+ NK cells in circulation and are largely tissue-resident. The frequency and number of CD56br NK cells in blood has been shown to increase following administration of low-dose IL-2 (LD-IL2), a therapy aimed to specifically expand CD4+ regulatory T cells (Tregs). Given the potential clinical application of LD-IL-2 immunotherapy across several immune diseases, including the autoimmune disease type 1 diabetes, a better understanding of the functional consequences of this expansion is urgently needed. In this study, we developed an in vitro co-culture assay with activated CD4+ T cells to measure NK cell killing efficiency. We show that CD56br and CD56dim NK cells show similar efficiency at killing activated CD4+ conventional T (Tconv) and Treg cell subsets. However, in contrast to CD56dim cells, CD56br NK cells preferentially target highly proliferative cells. We hypothesize that CD56br NK cells have an immunoregulatory role through the elimination of proliferating autoreactive CD4+ Tconv cells that have escaped Treg suppression. These results have implications for the interpretation of current and future trials of LD-IL-2 by providing evidence for a new, possibly beneficial immunomodulatory mechanism of LD-IL-2-expanded CD56br NK cells.

Role of IL-2/IL-2 receptor in pathogenesis of autoimmune disorders: Genetic and therapeutic aspects

Interleukin-2 (IL-2) is an important cytokine that plays a key role in the immune response. The IL-2 receptor (IL-2R) is composed of three subunits, alpha, beta, and gamma, with the alpha subunit having the highest affinity for IL-2. Several studies reported that immune dysregulation of IL-2 may cause tissue injury as well as damage leading to the pathogenesis of various autoimmune diseases such as acute necrotizing vasculitis in systemic lupus erythematosus (SLE), inflammatory synovitis in rheumatoid arthritis (RA), salivary and lacrimal gland dys-function in Sjogren syndrome (SS), obliterative vasculopathy fibrosis in systemic sclerosis (SSc), and inflammatory demyelination in multiple sclerosis (MS). The aim of this review paper was to examine the role of IL-2/IL-2R in various autoimmune disorders, taking into account recent advancements and discoveries, gaps in the current literature, ongoing debates, and potential avenues for future research. The focus of this review is on systemic lupus erythematosus, rheumatoid arthritis, systemic sclerosis, sjogren syndrome, and multiple sclerosis, which are all linked to the malfunctioning of IL-2/IL-2R. In genetic studies, gene polymorphisms of IL-2 such as IL-2 330/T, IL-2 330/G, and rs2069763 are involved in increasing the risk of SLE. Furthermore, genetic associations of IL-2/IL-2R such as rs791588, rs2281089, rs2104286, rs11594656, and rs35285258 are significantly associated with RA susceptibility. The IL-2 polymorphism including rs2069762A, rs6822844T, rs6835457G, and rs907715T are significant connections with systemic sclerosis. In addition, rs2104286 (IL-2), rs11594656 (IL-2RA), rs35285258 (IL-2RB) gene polymorphism significant increases the risk of multiple sclerosis. In therapeutic approaches, low-dose IL-2 therapy could regulate Tfr and Tfh cells, resulting in a reduction in disease activity in the SLE patients. In addition, elevated sIL-2R levels in the peripheral blood of SLE patients could be linked to an immunoregulatory imbalance, which may contribute to the onset and progression of SLE. Consequently, sIL-2R could potentially be a target for future SLE therapy. Moreover, Low dose-IL2 was well-tolerated, and low levels of Treg and high levels of IL-21 were associated with positive responses to Ld-IL2 suggested to be a safe and effective treatment for RA. Additionally, low-dose IL-2 treatment improves the exocrine glands' ability to secrete saliva in SS-affected mice. Whereas, Basiliximab targets the alpha chain of the IL-2 receptor suggested as a potential treatment for SSc. Also, pre-and post-treatment with Tregs, MDSCs, and IL-2 may have the potential to prevent EAE induction in patients with MS. It is suggested that further studies should be conducted on IL-2 polymorphism in Sjogren syndrome.

Rapamycin and Low-dose IL-2 Mediate an Immunosuppressive Microenvironment to Inhibit Benign Prostatic Hyperplasia

Benign prostatic hyperplasia (BPH) is a condition that becomes more common with age and manifests itself primarily as the expansion of the prostate and surrounding tissues. However, to date, the etiology of BPH remains unclear. In this respect, we performed single-cell RNA sequencing of prostate transition zone tissues from elderly individuals with different prostate volumes to reveal their distinct tissue microenvironment. Ultimately, we demonstrated that a reduced Treg/CD4+ T-cell ratio in the large-volume prostate and a relatively activated immune microenvironment were present, characterized partially by increased expression levels of granzymes, which may promote vascular growth and profibrotic processes and further exacerbate BPH progression. Consistently, we observed that the prostate gland of patients taking immunosuppressive drugs usually remained at a smaller volume. Furthermore, in mouse models, we confirmed that both suppression of the immune system with rapamycin and induction of Treg proliferation with low doses of IL-2 therapy indeed prevented the progression of BPH. Taken together, our findings suggest that an activated immune microenvironment is necessary for prostate volume growth and that Tregs can reverse this immune activation state, thereby inhibiting the progression of BPH.

Current Treatment Approach, Emerging Therapies and New Horizons in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE), the prototype of systemic autoimmune diseases is characterized by extreme heterogeneity with a variable clinical course. Renal involvement may be observed and affects the outcome. Hydroxychloroquine should be administered to every lupus patient irrespective of organ involvement. Conventional immunosuppressive therapy includes corticosteroids, methotrexate, cyclophosphamide, mycophenolate mofetil, azathioprine, cyclosporine and tacrolimus. However, despite conventional immunosuppressive treatment, flares occur and broad immunosuppression is accompanied by multiple side effects. Flare occurrence, target organ involvement, side effects of broad immunosuppression and increased knowledge of the pathogenetic mechanisms involved in SLE pathogenesis as well as the availability of biologic agents has led to the application of biologic agents in SLE management. Biologic agents targeting various pathogenetic paths have been applied. B cell targeting agents have been used successfully. Belimumab, a B cell targeting agent, has been approved for the treatment of SLE. Rituximab, an anti-CD20 targeting agent is also used in SLE. Anifrolumab, an interferon I receptor-targeting agent has beneficial effects on SLE. In conclusion, biologic treatment is applied in SLE and should be further evaluated with the aim of a good treatment response and a significant improvement in quality of life.