Low-dose Interleukin-2 Therapy Research Articles

Efficacy and safety of low-dose interleukin 2 in the treatment of moderate-to-severe bullous pemphigoid: A single center perspective-controlled trial

BackgroundRegulatory T cells (Tregs) are reduced in the peripheral blood and skin lesions of patients with bullous pemphigoid (BP). Low-dose interleukin 2 (IL-2) therapy can stimulate Tregs specifically, suggesting potential for the treatment of BP. ObjectiveTo evaluate the response to low-dose IL-2 therapy in the treatment of moderate-to-severe BP. MethodsForty-three patients with moderate-to-severe BP were included. The therapy included systemic corticosteroids with an initial dose of 0.5 mg/kg/d for moderate and 1.0 mg/kg/d for severe disease, respectively, combined with allowed immunosuppressants for the control group, whereas in addition to the same corticosteroid therapy, IL-2 (half million IU) was administered subcutaneously every other day for the treatment group for 8 weeks. The primary outcome was the number of days required to achieve disease control. Secondary outcomes included other clinical responses. ResultsThe number of days required to achieve disease control with the treatment group was (7.60 ± 3.00), which was shorter than in the control group (10.43 ± 3.06) (P = .008). The total amount of systemic corticosteroids was less, and no serious infections were detected in the treatment group. LimitationsSingle center, open-label study with short duration and small size. ConclusionOur trial supports the potential of low-dose IL-2 therapy for patients with moderate-to-severe BP, which showed earlier treatment responses.

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 IL2has 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.

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.

Retrospective analysis of low-dose interleukin-2 therapy on chronic autoimmune thyroid disease with concurrent systemic lupus erythematosus

Introduction Low-dose interleukin-2 (IL-2) regulates the homeostasis of CD4+ T cells by modulating the proportions of effector and regulatory T cells, thus reducing disease activity in patients with systemic lupus erythematosus (SLE). However, to date, no research has been carried out on the efficacy of low-dose IL-2 for treating autoimmune thyroid disease (AITD). The aim of this study was to observe the effects of IL-2 on AITD patients with concurrent SLE, and explore potential mechanism of action. Methods A retrospective analysis was conducted on 29 SLE patients with concurrent AITD. Among them, 11 patients were in IL-2 therapy group and 18 patients without IL-2 treatment were considered as control group. Two groups had similar disease activities and were treated with comparable regular strategy. Free triiodothyronine (FT3), free thyroxine (FT4), thyroxine(T4), triiodothyronine(T3), thyroid stimulating hormone (TSH), thyroglobulin antibody (TG-Ab), thyroid peroxidase antibody (TPO-Ab) levels and immune cell subgroups were measured. Results After receiving low-dose IL-2 therapy, the TG-Ab and TPO-Ab levels decreased drastically (TG-Ab p = 0.008, TPO-Ab p = 0.007), and the majority of the AITD patients became seronegative, while there was no discernible change in control group. In IL-2 group, percentage of CD4+ T cells showed a significant increase after treatment (p = 0.029), with an upward trend in the ratio of regulatory T (Treg) cells to follicular helper T (Tfh) cells (Treg/Tfh). The percentage as well as absolute count of B cells demonstrated a decreasing trend. Conclusion Low-dose IL-2 may downregulate the levels of TG-Ab and TPO-Ab by modulating the immune balance of Treg/Tfh and B-cells, providing new avenue for clinical treatment of AITD.

Low-dose interleukin-2 promotes immune regulation in face transplantation: A pilot study

Face transplantation is a life-changing procedure for patients with severe composite facial defects. However, it is hampered by high acute rejection rates due to the immunogenicity of skin allograft and toxicity linked to high doses of immunosuppression. To reduce immunosuppression-associated complications, we, for the first time in face transplant recipients, used low-dose interleukin 2 (IL-2) therapy to expand regulatory T cells (Tregs) in vivo and to enhance immune modulation, under close immunological monitoring of peripheral blood and skin allograft. Low-dose IL-2 achieved a sustained expansion (∼4-fold to 5-fold) of circulating Tregs and a reduction (∼3.5-fold) of B cells. Post-IL-2 Tregs exhibited greater suppressive function, characterized by higher expression of TIM-3 and LAG3co-inhibitory molecules. In the skin allograft, Tregs increased after low-dose IL-2 therapy. IL-2 induced a distinct molecular signature in the allograft with reduced cytotoxicity-associated genes (granzyme B and perforin). Two complications were observed during the trial: one rejection event and an episode of autoimmune hemolytic anemia. In summary, this initial experience demonstrated that low-dose IL-2 therapy was not only able to promote immune regulation in face transplant recipients but also highlighted challenges related to its narrow therapeutic window. More specific targeted Treg expansion strategies are needed to translate this approach to the clinic.

Low-dose interleukin-2 therapy in autoimmune and inflammatory diseases: facts and hopes

Low-dose interleukin-2 therapy in autoimmune and inflammatory diseases: facts and hopes

Absolute decrease in regulatory T cells and low-dose interleukin-2 therapy: restoring and expanding regulatory T cells to treat systemic sclerosis: a 24-week study.

Systemic sclerosis (SSc) is an autoimmune disease characterized by vascular lesions, immunological alterations and tissue fibrosis. There is some evidence of an imbalance between T-cell subsets in this disease. Interleukin (IL)-2 is a cytokine that can regulate the activity of immune cells and there is evidence that low-dose IL-2 therapy can be used to treat immune diseases. To investigate the changes of peripheral lymphocyte subsets, especially T helper (Th)17 and regulatory T (Treg) cells and the effects of low-dose IL-2 therapy in patients with SSc. In total, 66 patients with SSc and 49 sex- and age-matched healthy controls (HCs), were enrolled. The absolute numbers of peripheral lymphocyte subsets in these individuals were determined by flow cytometry. The 66 patients, were divided into 2 groups: 23 (the IL-2 group) were treated with low-dose (5.0 × 105 IU) IL-2 by subcutaneous injection daily for 5 days combined with conventional therapy, while the remaining 23 patients received conventional therapy only. Compared with HCs, the absolute numbers of peripheral T, CD4+ T, CD8+ T, natural killer and Treg cells were significantly lower in patients with SSc, with the most dramatic difference seen in both the absolute number and percentage of Treg cells in these patients, including new (previously untreated) cases, resulting in an imbalance (elevated ratio) between Th17 and Treg cells. At Week 24 after commencement of IL-2 treatment, Treg cells were markedly increased and tended to restore the balance of Th17 to Treg cells compared with baseline. Erythrocyte sedimentation rate, C-reactive protein, modified Rodnan Skin Score and visual analogue scale score were significantly decreased in both the IL-2 and non-IL-2 groups, indicating disease improvement. Notably, compared with those in the non-IL-2 group, patients treated with IL-2 had greater improvement. Our study showed that the absolute numbers of peripheral Treg cells together with total T, CD4+ T, CD8+ T and NK is significantly decreased, leading to an imbalance of Th17 to Treg cells in patients with SSc, and that low-dose IL-2 treatment could restore the balance of the two immune cells and reduce disease activity without obvious adverse effects.

Durability of clinical and immunologic responses to extended low-dose interleukin-2 therapy in patients with refractory chronic graft-versus-host disease.

Chronic graft-versus-host disease (cGVHD) remains a frequent cause of non-relapse morbidity and mortality after allogeneic hematopoietic stem cell transplantation. In our single center trials of low-dose interleukin-2 (LD IL-2), the immunomodulatory properties of regulatory T cells (Tregs) have been harnessed to treat steroid-refractory cGVHD (SR-cGVHD) safely and effectively in adults and children. In these trials, 50-60% of patients showed clinical improvement of their cGVHD manifestations with partial responses at the primary response endpoint of 8-12 weeks. Many patients continued extended duration LD IL-2 therapy and achieved deeper clinical responses, including some complete responses. However, the durability of the clinical and immunologic improvement following IL-2 discontinuation has not been reported previously. We examined 20 adult and 2 pediatric patients who received extended duration LD IL-2 for a median of 103 weeks (range, 21-258) and had stable improvement or resolution of their cGVHD symptoms before discontinuing LD IL-2 therapy. The median follow-up after stopping IL-2 was 203 weeks (range 92-599). During this time, 16 patients (73%) were able to wean off all systemic immunosuppression without disease flare or progression. Among 13 patients with available immune cell data, the median fold change in absolute Treg count was 0.58 between 1 to 10 weeks after stopping IL-2 whereas CD4+ conventional T-cell (Tcon) and CD8+ T-cell numbers remained stable. Despite a decline in Treg numbers after IL-2 discontinuation, Treg numbers remained above the pre-treatment baseline. In addition, many patients had sustained clinical improvement after stopping IL-2, suggesting that extended IL-2 therapy can lead to immune tolerance.

Low-dose interleukin-2 therapy in active systemic lupus erythematosus (LUPIL-2): a multicentre, double-blind, randomised and placebo-controlled phase II trial

ObjectivesA regulatory T cell (Treg) insufficiency due to shortage of interleukin-2 (IL-2) is central to the pathophysiology of systemic lupus erythematosus (SLE). We performed a multicentre, double-blinded, randomised, placebo-controlled phase...

Driving Role of Interleukin-2-Related Regulatory CD4+ T Cell Deficiency in the Development of Lung Fibrosis and Vascular Remodeling in a Mouse Model of Systemic Sclerosis.

Systemic sclerosis (SSc) is a debilitating autoimmune disease characterized by severe lung outcomes resulting in reduced life expectancy. Fra-2-transgenic mice offer the opportunity to decipher the relationships between the immune system and lung fibrosis. This study was undertaken to investigate whether the Fra-2-transgenic mouse lung phenotype may result from an imbalance between the effector and regulatory arms in the CD4+ T cell compartment. We first used multicolor flow cytometry to extensively characterize homeostasis and the phenotype of peripheral CD4+ T cells from Fra-2-transgenic mice and control mice. We then tested different treatments for their effectiveness in restoring CD4+ Treg cell homeostasis, including adoptive transfer of Treg cells and treatment with low-dose interleukin-2 (IL-2). Fra-2-transgenic mice demonstrated a marked decrease in the proportion and absolute number of peripheral Treg cells that preceded accumulation of activated, T helper cell type 2-polarized, CD4+ T cells. This defect in Treg cell homeostasis was derived from a combination of mechanisms including impaired generation of these cells in both the thymus and the periphery. The impaired ability of peripheral conventional CD4+ T cells to produce IL-2 may greatly contribute to Treg cell deficiency in Fra-2-transgenic mice. Notably, adoptive transfer of Treg cells, low-dose IL-2 therapy, or combination therapy changed the phenotype of Fra-2-transgenic mice, resulting in a significant reduction in pulmonary parenchymal fibrosis and vascular remodeling in the lungs. Immunotherapies for restoring Treg cell homeostasis could be relevant in SSc. An intervention based on low-dose IL-2 injections, as is already proposed in other autoimmune diseases, could be the most suitable treatment modality for restoring Treg cell homeostasis for future research.

Organ-specific response after low-dose interleukin-2 therapy for steroid-refractory chronic graft-versus-host disease

AbstractDespite new therapeutic options, treatment of steroid-refractory chronic graft-versus-host disease (SR-cGVHD) remains challenging as organ involvement and clinical manifestations are highly variable. In previous trials of low-dose interleukin-2 (LD IL-2), we established the safety and efficacy of LD IL-2 for the treatment of SR-cGVHD. In the present report, we combined five phase 1 or 2 clinical trials conducted at our center to investigate organ-specific response rate, coinvolvement of organs, predictors of organ-specific response, and its possible association with immune response. For the 105 adult patients included in this report, the overall response rate after 8 or 12 weeks of LD IL-2 was 48.6% and 53.3%, including late responses in patients who continued treatment for extended periods. Skin was the most frequent organ involved (84%). The organ-specific response rate was highest in liver (66.7%) followed by the gastrointestinal tract (62.5%), skin (36.4%), joint/muscle/fascia (34.2%), and lung (19.2%). In multivariable analysis, shorter time from diagnosis of cGVHD to IL-2 initiation, shorter time from transplant to IL-2 initiation, and fewer prior therapies were associated with overall response as well as skin response. For immunologic correlates, the ratio of regulatory T cells:conventional T cells (ie, CD4Treg:CD4Tcon) ratio at 1 week was significantly higher in patients with overall and skin response; skin response was significantly associated with lower number of total CD3 T cells, CD4Tcon cells, and CD8 T cells and a higher number of B cells. For lung responders, terminal effector memory cell counts were lower within all T-cell populations compared with nonresponders. Organ-specific mechanisms of injury should be investigated, and organ-specific targeted therapies need to be developed.

Low Dose IL-2 Therapy Induces T Regulatory Cell Derived Circulatory Exosomes Containing PDL1 and CD73 and Abrogates Development of Chronic Cardiac Allograft Rejection

<h3>Purpose</h3> Aim of the study is to determine the effect of low dose interleukin-2 (IL-2) therapy on the kinetics of induction of circulating exosomes and their immunological properties resulting in prevention of chronic rejection following allogeneic murine cardiac transplantation (HTx). <h3>Methods</h3> BALB/c (H2^d) to C57BL/6 (H2^b) HTx was performed heterotopically in the abdominal cavity. Costimulatory blockade consisting of MR1 (250 μg/ip day 0) and CTLA4-Ig (200 μg/ip day 2) was administered to induce tolerance. IL-2 (2000IU/day) was administered from day 14 post-transplant for 3 weeks. Sera were collected on days 7-100 for analysis of exosome induction and characterization of cardiac self-antigens (SAgs) (Myosin, Vimentin) by western blot. Foxp3, PDL1, CD73 in exosomes were detected using aldehyde bead - based flow cytometry. Antibodies (Abs) to donor MHC and SAgs were detected using immunofluorescence and ELISA respectively. <h3>Results</h3> BALB/c to C57BL/6 HTx acutely rejected (AR) with median survival time of 8 days. Costimulatory blockade prevented AR but developed chronic rejection with mean of 42 days circulating exosomes contained significantly higher levels of Myosin and Vimentin in the exosomes day 15 (p<0.05) and day 30 (p<0.01). Abs to MHC (32±13.8% vs 2±1.1; p<0.001) was detected on day 30, whereas Abs to Myosin (1114.21±443.4 ng/ml; p<0.0001) and Vimentin (519±241 ng/ml; p<0.0001) were detected on day45 during chronic rejection with fibrosis (57.1±20.7 vs 2.3±1.7%). Low dose IL-2 significantly prolonged the survival, 115 vs 42 (p<0.001) and did not induce exosomes with cardiac SAgs or developed Abs to MHC or SAgs. Low dose IL-2 not only abrogated chronic rejection but also induced splenic CD4+CD25+ Foxp3 T regulatory (Treg) cells in the allograft by day 45. Flow cytometry of circulatory exosomes isolated in day 45 also demonstrated increased Foxp3+ PDL1+ (3.3 fold) and FoxP3+ CD73+ (3 fold) compared to exosomes isolated on day 45 from chronic rejecting animals. <h3>Conclusion</h3> Our results demonstrate that low dose IL-2 abrogated the development of chronic rejection following HTx and induced circulating Treg cells derived exosomes with PDL1 and CD73 along with splenic Tregs and graft infiltrating FoxP3 cells.

Low-Dose IL-2 Therapy in Autoimmune and Rheumatic Diseases.

Regulatory T cells (Treg) are crucial for the maintenance of peripheral tolerance and for the control of ongoing inflammation and autoimmunity. The cytokine interleukin-2 (IL-2) is essentially required for the growth and survival of Treg in the peripheral lymphatic tissues and thus plays a vital role in the biology of Treg. Most autoimmune and rheumatic diseases exhibit disturbances in Treg biology either at a numerical or functional level resulting in an imbalance between protective and pathogenic immune cells. In addition, in some autoimmune diseases, a relative deficiency of IL-2 develops during disease pathogenesis leading to a disturbance of Treg homeostasis, which further amplifies the vicious cycle of tolerance breach and chronic inflammation. Low-dose IL-2 therapy aims either to compensate for this IL-2 deficiency to restore a physiological state or to strengthen the Treg population in order to be more effective in counter-regulating inflammation while avoiding global immunosuppression. Here we highlight key findings and summarize recent advances in the clinical translation of low-dose IL-2 therapy for the treatment of autoimmune and rheumatic diseases.

HLA-Restriction of Human Treg Cells Is Not Required for Therapeutic Efficacy of Low-Dose IL-2 in Humanized Mice.

Regulatory T (Treg) cells are essential to maintain immune homeostasis in the intestine and Treg cell dysfunction is associated with several inflammatory and autoimmune disorders including inflammatory bowel disease (IBD). Efforts using low-dose (LD) interleukin-2 (IL-2) to expand autologous Treg cells show therapeutic efficacy for several inflammatory conditions. Whether LD IL-2 is an effective strategy for treating patients with IBD is unknown. Recently, we demonstrated that LD IL-2 was protective against experimental colitis in immune humanized mice in which human CD4+ T cells were restricted to human leukocyte antigen (HLA). Whether HLA restriction is required for human Treg cells to ameliorate colitis following LD IL-2 therapy has not been demonstrated. Here, we show that treatment with LD IL-2 reduced 2,4,6-trinitrobenzensulfonic acid (TNBS) colitis severity in NOD.PrkdcscidIl2rg-/- (NSG) mice reconstituted with human CD34+ hematopoietic stem cells. These data demonstrate the utility of standard immune humanized NSG mice as a pre-clinical model system to evaluate therapeutics targeting human Treg cells to treat IBD.

Low-dose IL-2 therapy limits the reduction in absolute numbers of circulating regulatory T cells in rheumatoid arthritis.

Background:Circulating regulatory T cells (Tregs) are responsible for mediating immune tolerance and maintaining immunological homeostasis. Decreases in Tregs may be involved in the onset of rheumatoid arthritis (RA). Low-dose interleukin-2 (IL-2) has been considered for the treatment of inflammatory diseases mediated by T cells. This study focused on the status of circulating CD4+T subsets and the clinical feasibility of IL-2 therapies in patients with RA.Methods:The subjects included 888 patients with RA and 100 healthy controls (HCs); 233 RA patients received IL-2 treatment with 0.5 million international units (MIU)/day from days 1 through 5. The demographic features, disease activity, and levels of CD4+T cells measured by modified flow cytometry were collected in all RA patients before and after treatment.Results:RA patients had lower absolute Treg counts (but not Th17) compared with HCs, which was associated with disease activity; previously treated RA patients had the fewest circulating Tregs (p < 0.05). Patients treated with low-dose IL-2 had a three-fold increase in absolute anti-inflammatory Treg counts, as well as a two-fold increase in the other CD4+T subsets. Moreover, post-treatment levels of markers of disease activity in RA patients treated with IL-2 were significantly lower than the baseline values (p < 0.001), with no apparent side effects.Conclusion:Decreased absolute counts of circulating CD4+T lymphocyte subsets were observed in patients with RA. Circulating Tregs, which mediate immune tolerance, may be involved in the pathogenesis and progression of RA; however, this was ameliorated by low-dose IL-2, without obvious side effects.Plain language summary Low-dose IL-2 treatment for rheumatoid arthritis • Circulating Tregs may be involved in the pathogenesis and progression of RA.• The absolute count of Tregs was significantly correlated with disease activity measures.• Low-dose IL-2 was able to effectively expade Tregs and help for RA patients’ symptoms remission without evaluated side effects.

Low-dose Interleukin-2: Biology and therapeutic prospects in rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic aggressive arthritis that is characterized with systemic inflammation response, the production of abnormal antibodies, and persistent synovitis. One of the key mechanisms underlying the pathogenesis of RA is the imbalance of CD4 + T lymphocyte subsets, from T helper (Th) 17 cells and regulatory T (Treg) cells to T follicular helper (Tfh) cells and T follicular regulatory (Tfr) cells, which can mediate autoimmune inflammatory response to promote the overproduction of cytokines and abnormal antibodies. Although the treatment of RA has greatly changed due to the discovery of biological agents such as anti-TNF, the remission of it is still not satisfactory, thus, it is urgently required new treatment to realize the sustained remission of RA via restoring the immune tolerance. Interleukin-2 (IL-2) has been discovered to be a pleiotropic cytokine to promote inflammatory response and maintain immune tolerance. Low-dose IL-2 therapy is a driver of the imbalance between autoimmunity and immune tolerance towards immune tolerance, which has been tried to treat various autoimmune diseases. Recent researches show that low-dose IL-2 is a promising treatment for RA. In this review, we summarize the advances understandings in the biology of IL-2 and highlight the impact of the IL-2 pathway on the balance of Th17/Treg and Tfh/Tfr aiming to investigate the role of IL-2-mediated immune tolerance in RA and discuss the application and the therapeutic prospect of low-dose IL-2 in the treatment of RA.

Sustained Immunogenic and Clinical Effects of Low-Dose Interleukin-2 Therapy with an Intermittent Maintenance Method for Refractory Chronic Graft-Versus-Host Disease: Results of Phase1/2a LDIL2-01 Study

Introduction and Objectives Regulatory T cells (Treg) play a central role in the maintenance of immune tolerance. We previously reported that the altered Treg homeostasis in the prolonged lymphopenia after HSCT is one of the major pathogenesis of impaired Treg recovery leading to the onset of chronic GVHD and low-dose IL-2 can restore normal Treg homeostasis by a PD-1-dependent mechanism, resulting in the improvement of clinical GVHD symptoms. In these years, the tolerogenic effects of IL-2 have been tested for various autoimmune diseases by clinical trials. However, the schedules of IL-2 dosing in each trial are different and the optimal strategy to expand Treg is still unclear. Our murine study has shown that daily administration of IL-2 seems to be optimal for the initial expansion of Treg but less frequent dosing within the threshold could be preferable for the following maintenance of expanded Treg. Methods Based on the findings, we conducted a phase1/2a clinical trial of low-dose IL-2 for steroid-refractory chronic GVHD with a distinctive dosing schedule consisting of an initial induction phase (IL-2 dosing everyday for the first 4 weeks) and a subsequent maintenance phase (IL-2 dosing 3 times a week for the following 8 weeks). Patients who obtained clinical benefit by the 3 months could proceed to the extended therapy up to total 12 months. The appropriate single dose of IL-2 was examined by a three-step dose escalation design. Results A total of 12 patients were enrolled. None had progression of chronic GVHD or recurrent hematologic malignancy. Dose-limiting toxicity did not occur even at the maximum dose. All patients were evaluable for response, and 7 had clinically significant responses involving multiple sites. Response was observed most often in the joints (67%). One patient with oral GVHD and another patient with gastrointestinal GVHD achieved complete response. One patient with severe lung GVHD markedly improved pulmonary functional test (%FEV1; from 24.8% to 64.8 %) and activity of daily life (from bedridden to return to work). Treg were preferentially increased in all patients, with a peak median value almost 10 times the baseline value (P Conclusion These results indicate that the sustained efficacy of IL-2 against chronic GVHD does not necessarily require that Treg is maintained at a high level by continuing daily IL-2 administration over the long term. Our data provide important information for reconsidering IL-2 dosing methods from the viewpoint of long-term safety and possible combination with other treatments.

Superior Treg-Expanding Properties of a Novel Dual-Acting Cytokine Fusion Protein.

Autoimmune diseases are caused by uncontrolled endogenous immune responses against healthy cells. They may develop due to an impaired function of regulatory T cells (Tregs), which normally suppress self-specific effector immune cells. Interleukin 2 (IL-2) and tumor necrosis factor (TNF) have been identified as key players that promote expansion, function, and stability of Tregs. In vivo, both low-dose IL-2 therapy and TNF receptor 2 (TNFR2) agonism were shown to expand Tregs and alleviate autoimmunity. We here designed a novel dimeric dual-acting fusion cytokine, where mouse IL-2 is genetically linked to a TNFR2-selective single-chain TNF mutein (IL2-EHD2-sc-mTNFR2). IL2-EHD2-sc-mTNFR2 showed high affinity to TNFR2 and efficiently activated IL-2 and TNFR2-selective signaling pathways. Further, IL2-EHD2-sc-mTNFR2 promoted superior Treg expansion, with both the IL-2 and the TNFR2 agonist (sc-mTNFR2) component necessary for this biological response. Ultimately, we propose that IL2-EHD2-sc-mTNFR2 is a dual-acting cytokine that efficiently promotes Treg expansion and might have a superior therapeutic window than conventional IL-2-based drugs.

IL-2 Therapy Diminishes Renal Inflammation and the Activity of Kidney-Infiltrating CD4+ T Cells in Murine Lupus Nephritis.

An acquired deficiency of interleukin-2 (IL-2) and related disturbances in regulatory T cell (Treg) homeostasis play an important role in the pathogenesis of systemic lupus erythematosus (SLE). Low-dose IL-2 therapy was shown to restore Treg homeostasis in patients with active SLE and its clinical efficacy is currently evaluated in clinical trials. Lupus nephritis (LN), a challenging organ manifestation in SLE, is characterized by the infiltration of pathogenic CD4+ T cells into the inflamed kidney. However, the role of the Treg-IL-2 axis in the pathogenesis of LN and the mode of action of IL-2 therapy in the inflamed kidneys are still poorly understood. Using the (NZB × NZW) F1 mouse model of SLE we studied whether intrarenal Treg are affected by a shortage of IL-2 in comparison with lymphatic organs and whether and how intrarenal T cells and renal inflammation can be influenced by IL-2 therapy. We found that intrarenal Treg show phenotypic signs that are reminiscent of IL-2 deprivation in parallel to a progressive hyperactivity of intrarenal conventional CD4+ T cells (Tcon). Short-term IL-2 treatment of mice with active LN induced an expansion the intrarenal Treg population whereas long-term IL-2 treatment reduced the activity and proliferation of intrarenal Tcon, which was accompanied by a clinical and histological amelioration of LN. The association of these immune pathologies with IL-2 deficiency and their reversibility by IL-2 therapy provides important rationales for an IL-2-based immunotherapy of LN.

Low-dose interleukin-2 therapy in refractory systemic lupus erythematosus: an investigator-initiated, single-centre phase 1 and 2a clinical trial

Summary Background An acquired deficiency of interleukin-2 (IL-2) and related defects in regulatory T cell homeostasis are thought to play a crucial role in the pathogenesis of systemic lupus erythematosus. We hypothesised that reconstitution of regulatory T-cell homoeostasis with low doses of IL-2 would be beneficial to patients with systemic lupus erythematosus. Methods In this uncontrolled, phase 1 and 2a trial done in the Department of Rheumatology and Clinical Immunology at Charite—University Medicine Berlin (Berlin, Germany), we assessed the safety and tolerability of low-dose recombinant human IL-2 (aldesleukin) and its effects on regulatory T cells. We recruited patients aged 18–75 years with a confirmed diagnosis of systemic lupus erythematosus and moderate-to-severe disease activity despite previous treatment with at least two conventional therapies. Patients were given four cycles of low-dose aldesleukin daily for 5 days followed by a 9–16 day rest. The primary endpoints were safety and the number of patients who achieved at least a 100% increase in the proportion of CD25hi-expressing cells among circulating CD3 + CD4 + FOXP3 + CD127lo regulatory T cells at day 62 (ie, after four treatment cycles). Secondary endpoints included disease activity as measured by the Safety of Estrogens in Lupus National Assessment-Systemic Lupus Erythematosus Disease Activity Index (SELENA-SLEDAI) and the British Isles Lupus Assessment Group (BILAG) score, disease flares as measured by the SLEDAI flare index, auto-antibody and complement concentrations at day 62. Exploratory endpoints included various cellular and immunological parameters. The trial is registered with WHO/ICTRP, number DRK4858. Findings Between March 31, 2014, and May 27, 2016, 13 patients were screened, of whom ten met eligibility criteria and were enrolled in the trial. Two additional patients were treated between April 1, 2013, and March 11, 2014, in a compassionate use setting. Eleven (92%) of the 12 patients achieved the primary endpoint. 159 adverse events were recorded, 75 (47%) of which were treatment related. Most treatment-related adverse events were transient and mild to moderate (grade 1–2). The most common adverse event was injection-site reaction (20%). No serious adverse events occurred during the treatment period. In ten (83%) of 12 patients, SELENA-SLEDAI scores were lower at day 62 than at baseline, and no severe disease flares were observed during the treatment period. Decreased disease activity correlated with the magnitude of increase in the proportion of activated regulatory T cells. IL-2 treatment resulted in a preferential proliferation of regulatory T cells that retained suppressive capacity. We observed decreases in cells that are involved in the regulation of germinal-centre reactions. Interpretation Low-dose IL-2 therapy is safe and well tolerated and selectively promotes the expansion of functional regulatory T cells in patients with moderate-to-severe systemic lupus erythematosus. Low-dose IL-2 treatment might also be beneficial in reducing disease activity, although larger trials are needed to address efficacy. Funding German Research Foundation.