Interleukin-6 promotes systemic lupus erythematosus progression with Treg suppression approach in a murine systemic lupus erythematosus model

Downregulation of circular RNA ETS1 promotes SLE activity and inhibits Treg cell differentiation through miR-1205/FoxP3 molecular axis

PURPOSE

This study aimed to explore the mechanism by which systemic lupus erythematosus (SLE) activity is promoted through Treg inhibition from the perspective of ceRNA.

METHODS

qRT-PCR was used to detect the expressions of circETS1, miR-1205, and FoxP3 in clinical SLE patient samples. Overexpression of circETS1and miR-1205, along with knockdown of miR-1205 and FoxP3 were conducted in CD4+ T cells, while the proliferation of helper T cell 17 (Th17) and regulatory T cell (Treg) was detected. Arescue assay was performed to verify the molecular mechanism of circETS1/miR-1205/Foxp3 mRNA axis in regulating CD4+ T cell differentiation. In the in vivo experiment, the expression of miR-1205 in SLE mice was intervened, and renal function, inflammatory factors, and serum complement were measured. Additionally, Treg/Th17 cell ratio was detected by flow cytometry.

RESULTS

In SLE patients, Treg cells were found to decrease, while Th17 cells increased. Transfection with circETS1 overexpression led to CD4+ T cells differentiating into Treg cells, causing an imbalance in the Th17/Treg ratio. Transfection of miR-1205 mimic and si-FoxP3 could reverse the effect of circETS1 overexpression. Moreover, inhibiting the expression of miR-1205 showed therapeutic effects on SLE mice.

CONCLUSION

circETS1 inhibits Treg via the miR-1205/FoxP3 axis, thereby promoting SLE activity, which may become a new target for SLE treatment.

No evidence of genetic causal association between sex hormone-related traits and systemic lupus erythematosus: A two-sample Mendelian randomization study

OBJECTIVE

Previous studies have demonstrated an association between sex hormone-related traits and systemic lupus erythematosus (SLE). However, because of the difficulties in determining sequential temporality, the causal association remains elusive. In this study, we used two-sample Mendelian randomization (MR) to explore the genetic causal associations between sex hormone-related traits and SLE.

METHODS

We used a two-sample MR to explore the causal association between sex hormone-related traits and SLE. The summarized data for sex hormone-related traits (including testosterone, estradiol (E2), sex hormone-binding globulin (SHBG), and bioavailable testosterone (BT)) originated from large genome-wide association studies (GWASs) of European descent. Aggregated data for SLE were derived from the FinnGen consortium (835 cases and 300,162 controls). Random-effects inverse-variance weighted (IVW), MR-Egger, weighted median, simple mode, weighted mode, and fixed-effects IVW methods were used for the MR analysis. Random-effects IVW was the primary method used to analyze the genetic causal association between sex hormone-related traits and SLE. Heterogeneity of the MR results was detected using the IVW Cochran's Q estimates. The pleiotropy of MR results was detected using MR-Egger regression and the MR pleiotropy residual sum and outlier (MR-PRESSO) test. Finally, leave-one-out analysis was performed to determine whether MR results were affected by a single single-nucleotide polymorphism (SNP).

RESULTS

Random-effects IVW as the primary method showed that testosterone (odds ratio (OR), 0.87; 95% confidence interval (CI), 0.41-1.82; P = 0.705), E2 (OR, 0.95; 95% CI, 0.73-1.23; P = 0.693), SHBG (OR, 1.25; 95% CI, 0.74-2.13; P = 0.400), and BT (OR, 0.99; 95% CI, 0.67-1.47; P = 0.959) had no potential causal association with SLE. The MR-Egger, weighted median, simple mode, weighted mode, and fixed-effects IVW methods all indicated consistent results. The results of the MR-Egger regression showed that there was no pleiotropy in our MR analysis (P > 0.05). The IVW Cochran's Q estimates showed that the MR analysis results of E2, SHBG, and BT on SLE had no heterogeneity (P > 0.05), but testosterone and SLE had heterogeneity (P < 0.05). The leave-one-out analysis confirmed that a single SNP did not affect the MR results.

CONCLUSIONS

Our MR analysis demonstrated that genetically predicted testosterone, E2, SHBG, and BT levels were not associated with SLE risk, but the roles of other non-genetic pathways cannot be ruled out. Key Points • This is the first MR study to explore the causal association of sex hormone-related traits with SLE. • No evidence to support causal associations between sex hormone-related traits and SLE. • Our MR analysis may provide novel insights into the causal association between sex hormone-related traits and SLE risk.

Phase II, randomised, double-blind, multicentre study evaluating the safety and efficacy of filgotinib and lanraplenib in patients with lupus membranous nephropathy

Objectives

Patients with lupus membranous nephropathy (LMN) are at risk for prolonged proteinuria and progressive chronic kidney disease. There are no proven effective treatments for LMN, and controlled trials are lacking. This trial assessed the preferential Janus kinase 1 (JAK1) inhibitor filgotinib and the spleen tyrosine kinase inhibitor lanraplenib in patients with LMN.

Methods

This was a phase II, randomised, double-blind trial conducted at 15 centres in the USA to evaluate the safety and efficacy of filgotinib or lanraplenib for the treatment of LMN. Eligible patients were randomised 1:1 to receive either filgotinib or lanraplenib in a blinded fashion for up to 52 weeks. The primary endpoint was the per cent change in 24-hour urine protein from baseline to week 16.

Results

Nine patients were randomised to receive filgotinib (n=5) or lanraplenib (n=4). Four patients in the filgotinib group and one patient in the lanraplenib group completed week 16. There was a median reduction of 50.7% in 24-hour urine protein after 16 weeks of treatment with filgotinib (n=4), and the median Systemic Lupus Erythematosus Disease Activity Index from the Safety of Estrogens in Lupus National Assessment score remained stable. Filgotinib treatment was well tolerated. Limited conclusions can be drawn about treatment with lanraplenib.

Conclusion

The number of patients treated in this study was small, and only limited conclusions can be drawn. There may be a therapeutic benefit with filgotinib treatment, which may support future investigations with filgotinib or other JAK inhibitors in patients with LMN.

Trial registration number

NCT03285711.

Tofacitinib Ameliorates Lupus Through Suppression of T Cell Activation Mediated by TGF-Beta Type I Receptor

Autoreactive T cells play a crucial role in the pathogenesis of systemic lupus erythematosus (SLE). TGF-β type I receptor (TGFβRI) is pivotal in determining T cell activation. Here, we showed that TGFβRI expression in naïve CD4⁺ T cells was decreased in SLE patients, especially in those with high disease activity. Moreover, IL-6 was found to downregulate TGFβRI expression through JAK/STAT3 pathway in SLE patients. In vitro, the JAK inhibitor tofacitinib inhibited SLE T cell activating by upregulating TGFβRI expression in a dose-dependent manner. In MRL/lpr mice, tofacitinib treatment ameliorated the clinical indicators and lupus nephritis, as evidenced by reduced plasma anti-dsDNA antibody levels, decreased proteinuria, and lower renal histopathological score. Consistently, tofacitinib enhanced TGFβRI expression and inhibited T cell activation in vivo. TGFβRI inhibitor SB431542 reversed the effects of tofacitinib on T cell activation. Thus, our results have indicated that tofacitinib can suppress T cell activation by upregulating TGFβRI expression, which provides a possible molecular mechanism underlying clinical efficacy of tofacitinib in treating SLE patients.

Th cytokine profile in childhood-onset systemic lupus erythematosus

Background

Childhood-onset systemic lupus erythematosus (cSLE) is a kind of chronic inflammatory disease characterized by a highly abnormal immune system. This study aimed to detect the serum levels of Th (T helper) cytokines (IL-2, IL-4, IL-5, IL-6, IL-9, IL-10, IL-13, IL-17A, IL-17F, IL-21, IL-22, IFN-γ and TNF-α) in cSLE and healthy controls, and then to elucidate their association with clinical manifestations, disease activity and laboratory parameters. In order to provide clues for early diagnosis and timely intervention treatment of cSLE patients.

Methods

A total of 33 children with cSLE and 30 healthy children were enrolled in this study. Children in the cSLE group were classified into the inactive or active cSLE group according to their SLE disease activity index 2000 (SLEDAI-2 K) score. Th cytokine profiles in the peripheral blood were detected and analysed.

Results

Levels of IL-2, IL-10 and IL-21 in the cSLE group were significantly higher than those in the healthy control group (P < 0.05, P < 0.01 and P < 0.01, respectively). Expression of IL-2, IL-10 and IL-21 in the active cSLE group was significantly higher than that in the healthy control group (P < 0.05, P < 0.01 and P < 0.05, respectively), but that of IL-22 expression was markedly lower in the active cSLE group than in the healthy control group (P < 0.001). IL-21 in the inactive SLE group was significantly higher than that in the healthy control group (P < 0.05), and levels of IL-2 and IL-10 in the active cSLE group were significantly higher than those in the inactive cSLE group (P < 0.01 and P < 0.05). In-depth analysis showed that after excluding age, gender and drug interference, the levels of IL-2 (P < 0.05), IL-6 (P < 0.05) and IL-10 (P < 0.05) were still positively correlated with SLEDAI-2 K scores. However, the levels of IL-6 (P < 0.05) and IFN- γ (P < 0.05) were still negatively correlated with CD4⁺/CD8⁺, and the concentration of IL-6 (P < 0.05) was still positively correlated with the occurrence of nephritis.

Conclusion

This study provides a theoretical basis for the discovery of effective methods to regulate imbalance in T lymphocyte subsets in cSLE, which may lead to new approaches for the diagnosis of cSLE.

Azithromycin alleviates systemic lupus erythematosus via the promotion of M2 polarisation in lupus mice

Our previous study demonstrated that azithromycin could promote alternatively activated (M2) macrophages under lupus conditions in vitro, which might be beneficial for lupus treatment. Thus, the aim of this study was to further confirm whether azithromycin can drive M2 polarisation in lupus and ultimately alleviate systemic lupus erythematosus (SLE) in vivo. Lymphocyte-derived DNA (ALD-DNA)-induced mice (induced lupus model) and MRL-Fas^lpr mice (spontaneous lupus model) were both used in the experiment. First, we observed symptoms of lupus by assessing the levels of serum anti-dsDNA antibodies and serum creatinine and renal pathology. We found that both murine models showed increased levels of serum anti-dsDNA antibodies and creatinine, enhanced glomerular fibrosis and cell infiltration, basement membrane thickening and elevated IgG deposition. After azithromycin treatment, all these medical indexes were alleviated, and kidney damage was effectively reversed. Next, macrophage polarisation was assessed in the spleen and kidneys. Macrophage infiltration in the spleen was notably decreased after azithromycin treatment in both murine models, with a remarkably elevated proportion of M2 macrophages. In addition, the expression of interleukin (IL)-1, IL-6, tumour necrosis factor (TNF)-α, inducible nitric oxide synthase (iNOS), CD86, toll-like receptor (TLR)2 and TLR4 was extremely downregulated, while the expression of transforming growth factor (TGF)-β, arginase-1 (Arg-1), chitinase-like 3 (Ym-1), found in inflammatory zone (Fizz-1) and mannose receptor (CD206) was significantly upregulated in the kidneys after azithromycin treatment. Taken together, our results indicated for the first time that azithromycin could alleviate lupus by promoting M2 polarisation in vivo. These findings exploited the newly discovered potential of azithromycin, a conventional drug with verified safety, affordability and global availability, which could be a novel treat-to-target strategy for SLE via macrophage modulation.

Sex Hormones in Acquired Immunity and Autoimmune Disease

Women have stronger immune responses to infections and vaccination than men. Paradoxically, the stronger immune response comes at a steep price, which is the high incidence of autoimmune diseases in women. The reasons why women have stronger immunity and higher incidence of autoimmunity are not clear. Besides gender, sex hormones contribute to the development and activity of the immune system, accounting for differences in gender-related immune responses. Both innate and adaptive immune systems bear receptors for sex hormones and respond to hormonal cues. This review focuses on the role of sex hormones particularly estrogen, in the adaptive immune response, in health, and autoimmune disease with an emphasis on systemic lupus erythematosus.

Regulatory T Cells Compensation Failure Cause the Dysregulation of Immune Response in Pristane Induced Lupus Mice Model

Introduction

Regulatory T cells' (Tregs') role remains unclear in the pathogenesis of systemic lupus erythematosus (SLE). This study was aimed at monitoring the percentage of Tregs within 32 weeks and monitoring its relationship with the percentage of other T helper (Th) cell subsets and the levels of autoantibodies and pro-inflammatory cytokines in a murine SLE model induced by pristane.

Methods

Forty-eight female BALB/c mice were divided into a healthy control (HC) and a pristine-induced (PI) group. SLE was induced by a single 0.5 cc pristane intraperitoneal injection. Six from each group were sacrificed every eight weeks until 32 weeks post-pristane injection. Treg, Th1, Th2 and Th17 percentages from the spleen were measured using flowcytometry. ANA, IL-6 and IFN-α levels were measured from serum using ELISA.

Results

The Treg percentage from the PI group increased significantly at 16 weeks compared to the HC group, while Th1, Th2 and Th17 percentages decreased. Tregs in the PI group began to reduce from the 24th to 32nd weeks, followed by an elevation of the Th1, Th2 and Th17 percentages. Tregs were negatively correlated with Th1 and Th2. Tregs in the PI group had a negative correlation with ANA and IFN-α levels from serum, whereas Tregs had a positive correlation with IL-6 levels.

Conclusion

The compensation of Tregs observed at 16 weeks after pristane injection failed, marked by a decreasing number of Tregs, followed by an increase of Th subsets, pro-inflammatory cytokines and autoantibodies. This compensatory failure of Tregs could be affected by pro-inflammatory cytokines, such as IFN-α and IL-6.

Foxp3, Regulatory T Cell, and Autoimmune Diseases

Regulatory T cells (Tregs) represent a cell type that promotes immune tolerance to autologous components and maintains immune system homeostasis. The abnormal function of Tregs is relevant to the pathogenesis of systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and other autoimmune diseases. Therefore, therapeutic modulation of Tregs could be a potent means of treating autoimmune diseases. Human Tregs are diverse, however, and not all of them have immunosuppressive effects. Forkhead box P3 (Foxp3), a pivotal transcription factor of Tregs that is crucial in maintaining Treg immunosuppressive function, can be expressed heterogeneously or unstably across Treg subpopulations. Insights into modulating Treg differentiation on the level of DNA transcription or protein modification may improve the success of Treg modifying immunotherapies. In this review, we will summarize three main prospects: the regulatory mechanism of Foxp3, the influence on Foxp3 and Tregs in autoimmune diseases, then finally, how Tregs can be used to treat autoimmune diseases.

The phenolic fraction of extra virgin olive oil modulates the activation and the inflammatory response of T cells from patients with systemic lupus erythematosus and healthy donors

SCOPE

Systemic lupus erythematosus (SLE) is a chronic multiorgan autoimmune disease characterized by immune deregulation, which involves altered T-cell response and imbalance of cytokine production. The phenolic fraction (PE) of extra virgin olive oil (EVOO) possesses anti-inflammatory and immunomodulatory properties and exerts preventive effects in murine models of immune-inflammatory diseases, such as SLE. The present study was designed to determine the in vitro effects of the PE from EVOO on peripheral blood mononuclear cells (PBMC) from inactive patients with SLE and healthy donors.

METHODS AND RESULTS

T-cell phenotype was investigated by flow cytometry, cytokine levels were determined by ELISA, and protein expression was detected by Western blot. The PE of EVOO decreased the frequency of CD69⁺ cells and the secretion of IFN-γ, TNF-α, IL-6, IL-1β, and IL-10. Moreover, PE increased the expression of I-kappa-B-α and decreased extracellular signal regulated kinase phosphorylation on PBMC from patients with SLE and healthy donors.

CONCLUSION

PE modulates cytokine production and attenuates induced T-cell activation, probably through NF-κB signaling pathway, providing the first evidence that PE from EVOO has an anti-inflammatory and immunomodulatory role in SLE patients and it might therefore be considered as a dietary complement in SLE management.

Blunting Autoantigen-induced FOXO3a Protein Phosphorylation and Degradation Is a Novel Pathway of Glucocorticoids for the Treatment of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a chronic inflammatory autoimmune disease affecting multiple organs. Glucocorticoids (GCs), the potent anti-inflammatory drugs, remain as a cornerstone in the treatment for SLE; nevertheless, their clinical efficacy is compromised by the side effects of long term treatment and resistance. To improve the therapeutic efficacy of GCs in SLE, it is important to further decipher the molecular mechanisms of how GCs exert their anti-inflammatory effects. In this investigation, FOXO3a was identified as a molecule that was down-regulated in the course of SLE. Of interest, GC treatment was found to rescue FOXO3a expression both in SLE mice and in SLE patients. Gain- and loss-of-function studies demonstrated that FOXO3a played a crucial role in GC treatment of SLE via inhibiting inflammatory responses. Further studies showed that the up-regulation of FOXO3a by GCs relied on the suppression of pI3K/AKT-mediated FOXO3a phosphorylation and the arrest of FOXO3a in the nucleus. Finally, our data revealed that FOXO3a was critical for GC-mediated inhibition of NF-κB activity, which might involve its interaction with NF-κB p65 protein. Collectively, these data indicated that FOXO3a played an important role in GC treatment of SLE by suppressing pro-inflammatory response, and targeting FOXO3a might provide a novel therapeutic strategy against SLE.

The association of interleukin-31 polymorphisms with interleukin-31 serum levels and risk of systemic lupus erythematosus

Interleukin-31 (IL-31) is the most recently discovered member of the gp130/IL-6 cytokine family which is produced mainly by activated Th2 cells. IL-31 was proved to play a crucial role in autoimmune and inflammatory diseases such as atopic dermatitis, asthma, cutaneous T cell lymphomas, Kawasaki disease and allergic rhinitis. Previous studies have identified that IL-31 could significantly induce the release of proinflammatory cytokines IL-6. Moreover, a large number of studies have shown that IL-6 plays an important role in the pathogenesis of systemic lupus erythematosus (SLE). However, up to date, no study to data was reported on the relationship between IL-31 and SLE. Therefore, in the present study, we investigated the association between IL-31 polymorphisms and its serum levels with the risk of SLE in a Chinese population. We analyzed two single nucleotide polymorphisms of IL-31 gene rs7977932 C/G and rs4758680 G/T in 190 patients with SLE and 250 age- and sex-matched controls, using polymerase chain reaction-single base extension and DNA sequencing methods. Soluble IL-31 (sIL-31) levels were measured by ELISA. From this study, we found that there were significant differences in the genotype and allele frequencies of IL-31 gene rs7977932 C/G polymorphism between the group of patients with SLE and the control group (P < 0.05). sIL-31 levels were increased in patients with SLE compared with controls (P < 0.01). Moreover, genotypes carrying the IL-31 rs7977932 G variant allele were associated with increased IL-31 levels compared to the homozygous wild-type genotype in patients with SLE. The rs7977932 C/G polymorphism of IL-31 gene and its sIL-31 levels were associated with SLE in the Chinese population. Our data suggest that IL-31 gene may play a role in the development of SLE.

Pathogenic Inflammation and Its Therapeutic Targeting in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE, lupus) is a highly complex and heterogeneous autoimmune disease that most often afflicts women in their child-bearing years. It is characterized by circulating self-reactive antibodies that deposit in tissues, including skin, kidneys, and brain, and the ensuing inflammatory response can lead to irreparable tissue damage. Over many years, clinical trials in SLE have focused on agents that control B- and T-lymphocyte activation, and, with the single exception of an agent known as belimumab which targets the B-cell survival factor BAFF, they have been disappointing. At present, standard therapy for SLE with mild disease is the agent hydroxychloroquine. During disease flares, steroids are often used, while the more severe manifestations with major organ involvement warrant potent, broad-spectrum immunosuppression with cyclophosphamide or mycophenolate. Current treatments have severe and dose-limiting toxicities and thus a more specific therapy targeting a causative factor or signaling pathway would be greatly beneficial in SLE treatment. Moreover, the ability to control inflammation alongside B-cell activation may be a superior approach for disease control. There has been a recent focus on the innate immune system and associated inflammation, which has uncovered key players in driving the pathogenesis of SLE. Delineating some of these intricate inflammatory mechanisms has been possible with studies using spontaneous mouse mutants and genetically engineered mice. These strains, to varying degrees, exhibit hallmarks of the human disease and therefore have been utilized to model human SLE and to test new drugs. Developing a better understanding of the initiation and perpetuation of disease in SLE may uncover suitable novel targets for therapeutic intervention. Here, we discuss the involvement of inflammation in SLE disease pathogenesis, with a focus on several key proinflammatory cytokines and myeloid growth factors, and review the known outcomes or the potential for targeting these factors in SLE.

FOXP3(+) Treg Cells and Gender Bias in Autoimmune Diseases

CD4⁺CD25⁺ regulatory T (Treg) cells play a pivotal role in the maintenance of immune homeostasis, where the X-linked master transcription factor forkhead box P3 (FOXP3) determines Treg cell development and function. Genetic deficiency of foxp3 induces dysfunction of Treg cells and immuno-dysregulation, polyendocrinopathy, enteropathy, and X-linked syndrome in humans. Functionally deficient Treg cells or the development of exTreg cells positively correlate with autoimmune diseases, such as systemic lupus erythematosus (SLE), multiple sclerosis (MS), and ankylosing spondylitis (AS). In general, females are more susceptible to SLE and MS but less susceptible to AS, where the expression of FOXP3 and its protein complex are perturbed by multiple factors, including hormonal fluctuations, inflammatory cytokines, and danger signals. Therefore, it is critical to explore the potential molecular mechanisms involved and these differences linked to gender. Here, we review recent findings on the regulation of FOXP3 activity in Treg cells and also discuss gender difference in the determination of Treg cell function in autoimmune diseases.

Influences of laparoscopic-assisted gastrectomy and open gastrectomy on serum interleukin-6 levels in patients with gastric cancer among Asian populations: a systematic review

BACKGROUND

To compare the effects of laparoscopic-assisted gastrectomy (LAG) and open gastrectomy (OG) on serum interleukin-6 (IL-6) levels in gastric cancer (GC) patients from Asia.

METHODS

The following scientific literature databases were searched for relevant clinical studies: PubMed, EBSCO, Ovid, Wiley, Web of Science, Cochrane library, EMBASE, WANFANG and VIP databases. The studies retrieved from database searches were screened based on stringent inclusion and exclusion criteria to select high quality cohort studies for the present meta-analysis. The data extracted from final selected studies were analyzed using STATA 12.0 software.

RESULTS

A total of 54 studies were initially retrieved from database searches, and 11 clinical cohort studies were eventually enrolled in this meta-analysis. The 11 selected studies contained a combined total of 767 GC patients (427 patients in LAG group and 340 patients in OG group). Meta-analysis results demonstrated that postoperative serum IL-6 levels in GC patients in LAG group was significantly lower than the OG group (SMD = -2.16, 95% CI = -3.19 ~ -1.14, P < 0.001). The difference in serum IL-6 levels between the preoperative and postoperative GC patients was significantly lower in the LAG group compared to the difference found in the OG group (SMD = -3.44, 95% CI = -4.87 ~ -2.01, P < 0.001). Subgroup analysis based on country showed that, in both Chinese and Japanese GC patients, the postoperative increase in serum IL-6 levels in LAG group were significantly lower than the increase observed in the OG group (all P < 0.05). In Korean GC patients, the postoperative increase in serum IL-6 levels was not significantly different between the LAG group and OG group (all P > 0.05).

CONCLUSION

Our results provide strong evidence that LAG is associated with significantly lower serum IL-6 levels, compared to OG. Thus, LAG carries markedly lower risk of adverse inflammatory reactions in GC patients among Asian population.

iTreg induced from CD39(+) naive T cells demonstrate enhanced proliferate and suppressive ability

CD4(+)CD25(+)FoxP3(+) regulatory T (Treg) cells which consist of naturally occurring Treg (nTreg) and induced Treg (iTreg) cells are associated with the maintenance of immune homeostasis. Previous studies were focused on their potential to ameliorate graft-versus-host disease (GVHD) in human and mice. CD39 is a surface marker both expressed on CD4(+)CD25(-) T cells and Treg cells. CD39(+) Treg cells demonstrate stronger suppressive ability compared to conventional Treg cells. However, whether the potential of CD39(+) naïve T cells induced Treg cells is different from conventional naïve T cells induced Treg cells in vivo and vitro remains to be inconclusive. Here we demonstrate that CD39(+) iTreg cells show enhanced proliferation and suppressive ability as well as lower inflammatory cytokines compared to CD39(-) iTreg cells. To conclude, our findings demonstrate that CD39(+) iTreg cells acquire high suppressive capacity in vitro and vivo, and this may provide a new insight into Treg cell therapy in GVHD clinical trials.