Functional dynamics of Foxp3⁺ regulatory T cells in mice and humans

Circulating and intestinal regulatory T cells in inflammatory bowel disease: A systemic review and meta-analysis

Regulatory T cells (Tregs) play an important immunosuppressive role in inflammatory bowel disease (IBD). However, findings on the quantitative and functional changes of intestinal and circulating Tregs in patients with IBD are rather contradictory. We therefore conducted a meta-analysis on this issue. The pooled effect was assessed using the standardized mean difference (SMD) with a 95% confidence interval (CI), and subgroup analyses were performed to investigate heterogeneity. This analysis included 764 IBD (402 UC and 362 CD) patients and 341 healthy controls (HCs) pooled from 17 eligible studies. The percentage of circulating Tregs was significantly decreased in active IBD patients compared to HCs (SMD = -0.95, p < 0.001) and inactive IBD patients (SMD = -0.80, p < 0.001). There was no difference in the percentage of circulating Tregs between inactive IBD patients and HCs. The suppressive function of circulating Tregs was impaired in active IBD patients according to limited data (SMD = -0.75, p = 0.02). Besides, the percentage of intestinal Tregs was significantly higher in inflamed regions than in non-inflamed regions (SMD = 0.85, p < 0.001). Our study quantitatively summarized the quantitative and functional changes of Tregs and supported the therapeutic potential of Tregs in IBD. Moreover, additional research into the functions and characteristics of intestinal Tregs in IBD is needed.

The eIF4EBP-eIF4E axis regulates CD4+ T cell differentiation through modulation of T cell activation and metabolism

CD4⁺ T cells are critical for adaptive immunity, differentiating into distinct effector and regulatory subsets. Although the transcriptional programs underlying their differentiation are known, recent research has highlighted the importance of mRNA translation in determining protein abundance. We previously conducted genome-wide analysis of translation in CD4⁺ T cells revealing distinct translational signatures distinguishing these subsets, identifying eIF4E as a central differentially translated transcript. As eIF4E is vital for eukaryotic translation, we examined how altered eIF4E activity affected T cell function using mice lacking eIF4E-binding proteins (BP^-/-). BP^-/- effector T cells showed elevated Th1 responses ex vivo and upon viral challenge with enhanced Th1 differentiation observed in vitro. This was accompanied by increased TCR activation and elevated glycolytic activity. This study highlights how regulating T cell-intrinsic eIF4E activity can influence T cell activation and differentiation, suggesting the eIF4EBP-eIF4E axis as a potential therapeutic target for controlling aberrant T cell responses.

CPHEN-014: Comprehensive phenotyping of mouse regulatory T cells relevant to viral infections

Regulatory T (Treg) cells are a specialized subpopulation of CD4⁺ T cells that enforce peripheral immune tolerance. Treg cells act to suppress exuberant immune responses, limit inflammation, and promote tissue repair, thereby maintaining homeostasis and tolerance to self-antigens and those of the commensal microbial flora. Treg cells are characterized by the expression of the master regulator Foxp3, which plays a major role in Treg cells development and function. Under inflammatory conditions, Foxp3⁺ Treg cells may acquire effector T cell programs that modify their phenotype and function, reflecting their plasticity. During microbial infections, Treg cells act to limit the immunopathology triggered by the host immune response to pathogens albeit at the potential risk of pathogen persistence. In this review, we will discuss the influence of Treg cells on the outcome of viral infection and will give an overview of the Treg phenotype at steady-state and in inflammatory conditions.

The Yin and Yang of Targeting KLRG1+ Tregs and Effector Cells

The literature surrounding KLRG1 has primarily focused on NK and CD8⁺ T cells. However, there is evidence that the most suppressive Tregs express KLRG1. Until now, the role of KLRG1 on Tregs has been mostly overlooked and remains to be elucidated. Here we review the current literature on KLRG1 with an emphasis on the KLRG1⁺ Treg subset role during cancer development and autoimmunity. KLRG1 has been recently proposed as a new checkpoint inhibitor target, but these studies focused on the effects of KLRG1 blockade on effector cells. We propose that when designing anti-tumor therapies targeting KLRG1, the effects on both effector cells and Tregs will have to be considered.

Regulatory T Cells in Autoimmune Vasculitis

Blood vessels are indispensable for host survival and are protected from inappropriate inflammation by immune privilege. This protection is lost in patients with autoimmune vasculitides, a heterogeneous group of diseases causing damage to arteries, arterioles, and capillaries. Vasculitis leads to vascular wall destruction and/or luminal occlusion, resulting in hemorrhage and tissue ischemia. Failure in the quantity and quality of immunosuppressive regulatory T cells (Treg) has been implicated in the breakdown of the vascular immune privilege. Emerging data suggest that Treg deficiencies are disease-specific, affecting distinct pathways in distinct vasculitides. Mechanistic studies have identified faulty CD8+ Tregs in Giant Cell Arteritis (GCA), a vasculitis of the aorta and the large aortic branch vessels. Specifically, aberrant signaling through the NOTCH4 receptor expressed on CD8+ Treg cells leads to rerouting of intracellular vesicle trafficking and failure in the release of immunosuppressive exosomes, ultimately boosting inflammatory attack to medium and large arteries. In Kawasaki’s disease, a medium vessel vasculitis targeting the coronary arteries, aberrant expression of miR-155 and dysregulated STAT5 signaling have been implicated in undermining CD4+ Treg function. Explorations of mechanisms leading to insufficient immunosuppression and uncontrolled vascular inflammation hold the promise to discover novel therapeutic interventions that could potentially restore the immune privilege of blood vessels and pave the way for urgently needed innovations in vasculitis management.

Crosstalk Between the Tumor Microenvironment and Cancer Cells: A Promising Predictive Biomarker for Immune Checkpoint Inhibitors

Immune checkpoint inhibitors (ICIs) have changed the landscape of cancer treatment and are emerging as promising curative treatments in different type of cancers. However, only a small proportion of patients have benefited from ICIs and there is an urgent need to find robust biomarkers for individualized immunotherapy and to explore the causes of immunotherapy resistance. In this article, we review the roles of immune cells in the tumor microenvironment (TME) and discuss the effects of ICIs on these cell populations. We discuss the potential of the functional interaction between the TME and cancer cells as a predictive biomarker for ICIs. Furthermore, we outline the potential personalized strategies to improve the effectiveness of ICIs with precision.

Immune Microenvironment: New Insight for Familial Adenomatous Polyposis

Currently, the main treatment for familial adenomatous polyposis (FAP) is surgery, however, surgery is far from ideal as there are many complications such as uncontrollable bowel movements, pouch inflammation, anastomotic stricture, and secondary fibroids. Therefore, it is necessary to further expand the understanding of FAP and develop new treatments for FAP. The immune microenvironment including immune cells and cytokines, plays an important role in FAP and the progression of FAP to adenocarcinoma, thus it may be a promising treatment for FAP. In the current review, we summarized the recent progress in the immune microenvironment of FAP.

Methylation-Sensitive Restriction Enzyme Quantitative Polymerase Chain Reaction Enables Rapid, Accurate, and Precise Detection of Methylation Status of the Regulatory T Cell (Treg)-Specific Demethylation Region in Primary Human Tregs

Human regulatory T cells (Tregs) have been implicated in cancer immunotherapy and are also an emerging cellular therapeutic for the treatment of multiple indications. Although Treg stability during ex vivo culture has improved, methods to assess Treg stability such as bisulfite Sanger sequencing to determine the methylation status of the Treg-specific demethylated region (TSDR) have remained unchanged. Bisulfite Sanger sequencing is not only costly and cumbersome to perform, it is inaccurate because of relatively low read counts. Bisulfite next-generation sequencing, although more accurate, is a less accessible method. In this study, we describe the application of methylation-sensitive restriction enzymes (MSRE) and quantitative PCR (qPCR) to determine the methylation status of the TSDR. Using known ratios of Tregs and non-Tregs, we show that MSRE-qPCR can distinguish the methylation status of the TSDR in populations of cells containing increasing proportions of Tregs from 0 to 100%. In a comparison with values obtained from an established bisulfite next-generation sequencing approach for determining the methylation status of the TSDR, our MSRE-qPCR results were within 5% on average for all samples with a high percentage (>70%) of Tregs, reinforcing that MSRE-qPCR can be completed in less time than other methods with the same level of accuracy. The value of this assay was further demonstrated by quantifying differences in TSDR methylation status of Tregs treated with and without rapamycin during an ex vivo expansion culture. Together, we show that our novel application of the MSRE-qPCR to the TSDR is an optimal assay for accurate assessment of Treg purity.

Vitamin D Supplementation Modulates ICOS+ and ICOS- Regulatory T Cell in Siblings of Children With Type 1 Diabetes

OBJECTIVES

Vitamin D plays an immunoregulatory activity. The aim of this study was to assess the correlation between blood serum 25(OH)D levels and Th17 and Treg circulating subsets, mainly Treg/inducible costimulatory-positive (ICOS+), which seems to have a protective role in autoimmunity, in children with type 1 diabetes mellitus (T1D) and their healthy siblings (S). The secondary aim was to evaluate the impact of vitamin D supplementation on these subsets.

PATIENTS AND METHODS

22 T1D and 33 S were enrolled. Glucose, hemoglobin A1c, 25 OH vitamin D (25[OH]D), T helper type 17 (Th17; CD4+CCR6+), regulatory T cells (Treg; CD4+CD25+Foxp3+), and Treg/ICOS+ cells were evaluated. According to human leukocyte antigen (HLA) haplotypes, subjects were classified as "at risk" (HLA+), "protective haplotypes" (HLA-; "nested controls"), and "undetermined" (HLAUND). T1D and S subjects were supplemented with cholecalciferol 1000 IU/die and evaluated after 6 months.

RESULTS

Vitamin D insufficiency (74.4%) and deficiency (43%) were frequent. S subjects with 25(OH)D levels <25 nmol/L had Th17, Treg (p < 0.01), and Treg/ICOS+ (P < 0.05) percentages higher than subjects with 25(OH)D >75 nmol/L. Treg/ICOS+ percentages (P < 0.05) were higher in HLA- S subjects compared to percentages observed in S with T1D. At baseline, in S subjects, a decreasing trend in Th17 and Treg/ICOS+ values (P < 0.05) from vitamin D deficiency to sufficiency was observed; 25(OH)D levels were negative predictors of Treg/ICOS+ (R2 = 0.301) and Th17 percentages (R2 = 0.138). After 6 months, supplemented S subjects showed higher 25(OH)D levels (P < 0.0001), and lower Th17 (P < 0.0001) and Treg/ICOS+ (P < 0.05) percentages than at baseline; supplemented T1D patients only had a decrease in Th17 levels (P < 0.05).

CONCLUSION

Serum 25(OH)D levels seem to affect Th17 and Treg cell subsets in S subjects, consistent with its immunomodulating role. HLA role should be investigated in a larger population.

Molecular Mechanisms Controlling Foxp3 Expression in Health and Autoimmunity: From Epigenetic to Post-translational Regulation

The discovery of the transcription factor Forkhead box-p3 (Foxp3) has shed fundamental insights into the understanding of the molecular determinants leading to generation and maintenance of T regulatory (Treg) cells, a cell population with a key immunoregulatory role. Work over the past few years has shown that fine-tuned transcriptional and epigenetic events are required to ensure stable expression of Foxp3 in Treg cells. The equilibrium between phenotypic plasticity and stability of Treg cells is controlled at the molecular level by networks of transcription factors that bind regulatory sequences, such as enhancers and promoters, to regulate Foxp3 expression. Recent reports have suggested that specific modifications of DNA and histones are required for the establishment of the chromatin structure in conventional CD4⁺ T (Tconv) cells for their future differentiation into the Treg cell lineage. In this review, we discuss the molecular events that control Foxp3 gene expression and address the associated alterations observed in human diseases. Also, we explore how Foxp3 influences the gene expression programs in Treg cells and how unique properties of Treg cell subsets are defined by other transcription factors.

Rebalancing Immune Homeostasis to Treat Autoimmune Diseases

During homeostasis, interactions between tolerogenic dendritic cells (DCs), self-reactive T cells, and T regulatory cells (Tregs) contribute to maintaining mammalian immune tolerance. In response to infection, immunogenic DCs promote the generation of proinflammatory effector T cell subsets. When complex homeostatic mechanisms maintaining the balance between regulatory and effector functions become impaired, autoimmune diseases can develop. We discuss some of the newest advances on the mechanisms of physiopathologic homeostasis that can be employed to develop strategies to restore a dysregulated immune equilibrium. Some of these designs are based on selectively activating regulators of immunity and inflammation instead of broadly suppressing these processes. Promising approaches include the use of nanoparticles (NPs) to restore Treg control over self-reactive cells, aiming to achieve long-term disease remission, and potentially to prevent autoimmunity in susceptible individuals.

Dexamethasone affects day/night development and function of thymus-derived T regulatory cells

Thymus-derived T regulatory (tTregs) cells play a crucial role in the maintenance of tolerance and immune homeostasis. Mechanisms and factors regulating tTreg development and function are widely investigated, but to a large degree still remain unclear. Our previous findings demonstrated that, in physiological conditions, the development and suppressive function of tTregs demonstrated day/night rhythmicity, which correlated with the concentration of plasma corticosterone and the expression of glucocorticoid receptors. In this study we ask whether synthetic glucocorticoids commonly used to inhibit excessive activity of the immune system, can modulate the development and suppressive function of tTregs in vivo depending on the time of administration. Young C57BL/6 male and female mice were injected intraperitoneally with a single dose of dexamethasone at two time points of the day: 7.00-8.00 a.m. and 7.00-8.00 p.m. The experimental can be used to indicate on the potentially expected positive or adverse side effects and can constitute also a good model for the assessment of the effects of long-term therapy. The results of our studies demonstrated the increase of the percentage of tTregs at both time points in male mice, but only in the evening in females. The suppressive activity of tTregs increased independently on the day time of in female mice, but in the morning only in males. We concluded that in the condition of dexamethasone supplementation, the elevated suppressive potential of tTregs is balanced by the induction apoptosis in order to prevent excessive suppression.

Beneficial effects of curtailing immune susceptibility in an Alzheimer's disease model

BACKGROUND

Currently, there are no effective therapeutic options for Alzheimer's disease, the most common, multifactorial form of dementia, characterized by anomalous amyloid accumulation in the brain. Growing evidence points to neuroinflammation as a major promoter of AD. We have previously shown that the proinflammatory cytokine TNFSF10 fuels AD neuroinflammation, and that its immunoneutralization results in improved cognition in the 3xTg-AD mouse.

METHODS

Here, we hypothesize that inflammatory hallmarks of AD might parallel with central and peripheral immune response dysfunction. To verify such hypothesis, we used a triple transgenic mouse model of AD. 3xTg-AD mice were treated for 12 months with an anti-TNFSF10 antibody, and thereafter immune/inflammatory markers including COX2, iNOS, IL-1β and TNF-α, CD3, GITR, and FoxP3 (markers of regulatory T cells) were measured in the spleen as well as in the hippocampus.

RESULTS

Spleens displayed accumulation of amyloid-β1-42 (Aβ1-42), as well as high expression of Treg cell markers FoxP3 and GITR, in parallel with the increased levels of inflammatory markers COX2, iNOS, IL-1β and TNF-α, and blunted IL-10 expression. Moreover, CD3 expression was increased in the hippocampus, consistently with FoxP3 and GITR. After chronic treatment of 3xTg-AD mice with an anti-TNFSF10 antibody, splenic FoxP3, GITR, and the above-mentioned inflammatory markers expression was restored to basal levels, while expression of IL-10 was increased. A similar picture was observed in the hippocampus. Such improvement of peripheral and CNS inflammatory/immune response was associated with decreased microglial activity in terms of TNFα production, as well as decreased expression of both amyloid and phosphorylated tau protein in the hippocampus of treated 3xTg-AD mice. Interestingly, we also reported an increased expression of both CD3 and FoxP3, in sections from human AD brain.

CONCLUSIONS

We suggest that neuroinflammation in the brain of 3xTg-AD mice triggered by TNFSF10 might result in a more general overshooting of the immune response. Treatment with an anti-TNFSF10 antibody blunted inflammatory processes both in the spleen and hippocampus. These data confirm the detrimental role of TNFSF10 in neurodegeneration, and corroborate the hypothesis of the anti-TNFSF10 strategy as a potential treatment to improve outcomes in AD.

Signaling Through gp130 Compromises Suppressive Function in Human FOXP3+ Regulatory T Cells

The CD4⁺FOXP3⁺ regulatory T cell (Treg) subset is an indispensable mediator of immune tolerance. While high and stable expression of the transcription factor FOXP3 is considered a hallmark feature of Treg cells, our previous studies have demonstrated that the human FOXP3⁺ subset is functionally heterogeneous, whereby a sizeable proportion of FOXP3⁺ cells in healthy individuals have a diminished capacity to suppress the proliferation and cytokine production of responder cells. Notably, these non-suppressive cells are indistinguishable from suppressive Treg cells using conventional markers of human Treg. Here we investigate potential factors that underlie loss of suppressive function in human Treg cells. We show that high expression of the IL-6 family cytokine receptor subunit gp130 identifies Treg cells with reduced suppressive capacity ex vivo and in primary FOXP3⁺ clones. We further show that two gp130-signaling cytokines, IL-6 and IL-27, impair the suppressive capacity of human Treg cells. Finally, we show that gp130 signaling reduces the expression of the transcription factor Helios, whose expression is essential for stable Treg function. These results highlight the role of gp130 in regulating human Treg function, and suggest that modulation of gp130 signaling may serve as a potential avenue for the therapeutic manipulation of human Treg function.

The Effects of Immunosuppressive Factors on Primary Dendritic Cells from C57BL/6 and CBA Mice

Introduction

Dendritic cells (DCs) control immune responses by modulating T and B cells towards effector or tolerogenic responses. In this study, we evaluated the effects of different immunosuppressive molecules on the phenotypic and functional characteristics of primary dendritic cells from C57BL/6 and CBA mice.

Methods

DCs were derived from bone marrow cells in the presence of rmGM-CSF and rmIL-4. DCs were then treated with different types of immunosuppressive molecules (rmIL-10, rmTGF-β, and BAY 11-7082) and cocultured with syngeneic splenocytes. The amount of CD4+CD25hiFoxP3+ Tregs, IL-10 expression, and proliferation were evaluated.

Results

Tolerogenic factors were found to have different effects on DCs C57Bl/6 mice. In C57Bl/6 mice, BAY 11-7082 alone had no effect on the expression of DC maturation molecules (CD80, CD86). Transforming growth factor beta (TGF-β), alone and in combination with BAY 11-7082, reduced the expression of these molecules. Cocultivation of DCs with splenocytes in the presence of TGF-β and BAY 11-7082 favored regulatory T cell (CD4+CD25hiFoxP3+) differentiation and disfavored differentiation of CD4+ T cells producing IL-10. In CBA mice, we found that rmIL-10 and rmTGF-β have a weak effect on maturation of DCs and their functional properties to induce Treg cells and IL-10 production.

Conclusion

These results indicate that TGF-β and IL-10 have different effects on the phenotypic and functional characteristics of DCs and that the NF-κB inhibitor, BAY 11-7082, has no synergistic effect on these treatments. In mice with an opposite nature of the immune response, the effects of immunoregulatory cytokines (IL-10 and TGF-b) differ on maturation of dendritic cells.

Molecular Characterization and Biological Function of a Novel LncRNA CRNG in Swine

Our previous study has showed that a novel gene is differentially expressed in the liver of cyadox-fed piglets, but its sequence and function are unknown. Here, rapid amplification of cDNA ends (RACE) and bioinformatics analysis showed that the novel gene is 953 bp without protein-coding ability and locates in chromosome 11. Hence, we identified the novel gene as long non-coding RNA (lncRNA) and named it cyadox-related novel gene (CRNG). Fluorescence in situ hybridization (FISH) showed that CRNG mainly distributes in cytoplasm. Moreover, microarray assay in combination with CRNG interference and overexpression showed that the differential genes such as ANPEP, KITLG, STAT5A, FOXP3, miR-451, IL-2, IL-10, IL-6, and TNF-α are mainly involved in viral and pathogens infection and the immune-inflammatory responses in PK-15 cells. This work reveals that CRNG might play a role in preventing the host from being infected by pathogens and viruses and exerting immune regulatory effects in the cytoplasm, which may be involved in prophylaxis of cyadox in piglets.

Lung Injury and Loss of Regulatory T Cells Primes for Lung-Restricted Autoimmunity

Lung transplantation is a life-saving therapy for several end-stage lung diseases. However, lung allografts suffer from the lowest survival rate predominantly due to rejection. The pathogenesis of alloimmunity and its role in allograft rejection has been extensively studied and multiple approaches have been described to induce tolerance. However, in the context of lung transplantation, dysregulation of mechanisms, which maintain tolerance against self-antigens, can lead to lung-restricted autoimmunity, which has been recently identified to drive the immunopathogenesis of allograft rejection. Indeed, both preexisting as well as de novo lung-restricted autoimmunity can play a major role in the development of lung allograft rejection. The three most widely studied lung-restricted self-antigens include collagen type I, collagen type V, and k-alpha 1 tubulin. In this review, we discuss the role of lung-restricted autoimmunity in the development of both early as well as late lung allograft rejection and recent literature providing insight into the development of lung-restricted autoimmunity through the dysfunction of immune mechanisms which maintain peripheral tolerance.

Pleiotropic Effects of IL-33 on CD4+ T Cell Differentiation and Effector Functions

IL-33, a member of the IL-1 family of cytokines, was originally described in 2005 as a promoter of type 2 immune responses. However, recent evidence reveals a more complex picture. This cytokine is released locally as an alarmin upon cellular damage where innate cell types respond to IL-33 by modulating their differentiation and influencing the polarizing signals they provide to T cells at the time of antigen presentation. Moreover, the prominent expression of the IL-33 receptor, ST2, on GATA3⁺ T helper 2 cells (T_H2) demonstrated that IL-33 could have a direct impact on T cells. Recent observations reveal that T-bet⁺ T_H1 cells and Foxp3⁺ regulatory T (T_REG) cells can also express the ST2 receptor, either transiently or permanently. As such, IL-33 can have a direct effect on the dynamics of T cell populations. As IL-33 release was shown to play both an inflammatory and a suppressive role, understanding the complex effect of this cytokine on T cell homeostasis is paramount. In this review, we will focus on the factors that modulate ST2 expression on T cells, the effect of IL-33 on helper T cell responses and the role of IL-33 on T_REG cell function.

Altered T-cell subsets and transcription factors in latent autoimmune diabetes in adults taking sitagliptin, a dipeptidyl peptidase-4 inhibitor: A 1-year open-label randomized controlled trial

AIMS/INTRODUCTION

Dipeptidyl peptidase-4 inhibitor has been proven to improve glycemic control and β-cell function in latent autoimmune diabetes in adults (LADA). The potential immune modulation mechanism is still unknown. Thus, we tested T-lymphocyte subsets and expression of relevant transcription factors in LADA patients with sitagliptin intervention for up to 1-year.

MATERIALS AND METHODS

A total of 40 LADA patients were randomly assigned to sitagliptin and/or insulin treatment (SITA group; n = 20) or insulin alone treatment (CONT group; n = 20). Peripheral blood mononuclear cells were isolated at baseline, 6 months and 12 months. The percentage of T-lymphocyte subsets (T helper 1, T helper 2, T helper 17 and regulatory T cells) tested by flow cytometry, and the messenger ribonucleic acid expression (T box expressed in T cells [T-BET], GATA binding protein 3 [GATA3], forkhead box protein 3 [FOXP3] and related orphan receptor C [RORC]) tested by real-time polymerase chain reaction were determined at baseline, 6 months and 12 months.

RESULTS

The percentage of regulatory T cells in the SITA group was significantly lower than that of the CONT group at baseline. The percentage of T helper 2 cells was higher than that of the CONT group at 6 months and 12 months. At 12 months, the percentage of T helper 17 cells was lower in the SITA group than that of the CONT group. After a 1-year visit, the messenger ribonucleic acid expression levels of T-BET expressed in T cells and RORC in the SITA group were significantly lower than at baseline. Whereas that of RORC in the CONT group were significantly lower than that at baseline.

CONCLUSIONS

The data confirmed that sitagliptin altered the phenotype of T cells and downregulated the expression of T-BET and RORC in LADA patients, and ameliorated glycemic control in LADA patients.

Scutellarin Prevents Angiogenesis in Diabetic Retinopathy by Downregulating VEGF/ERK/FAK/Src Pathway Signaling

BACKGROUND

Diabetic retinopathy (DR) is a serious microvascular complication of diabetes. This study demonstrates the antiangiogenic effects of scutellarin (SCU) on high glucose- and hypoxia-stimulated human retinal endothelial cells (HRECs) and on a diabetic rat model by oral administration. The antiangiogenic mechanisms of SCU in vitro and in vivo were investigated.

METHOD

HRECs were cultured in high glucose- (30 mM D-glucose) and hypoxia (cobalt chloride-treated)-stimulated diabetic condition to evaluate the antiangiogenic effects of SCU by CCK-8 test, cell migration experiment (wound healing and transwell), and tube formation experiment. A streptozotocin-induced type II diabetic rat model was established to measure the effects of oral administration of SCU on protecting retinal microvascular dysfunction by Doppler waveforms and HE staining. We further used western blot, luciferase reporter assay, and immunofluorescence staining to study the antiangiogenic mechanism of SCU. The protein levels of phospho-ERK, phospho-FAK, phospho-Src, VEGF, and PEDF were examined in HRECs and retina of diabetic rats.

RESULT

Our results indicated that SCU attenuated diabetes-induced HREC proliferation, migration, and tube formation and decreased neovascularization and resistive index in the retina of diabetic rats by oral administration. SCU suppressed the crosstalk of phospho-ERK, phospho-FAK, phospho-Src, and VEGF in vivo and in vitro.

CONCLUSIONS

These results suggested that SCU can be an oral drug to alleviate microvascular dysfunction of DR and exerts its antiangiogenic effects by inhibiting the expression of the crosstalk of VEGF, p-ERK, p-FAK, and p-Src.

Expression of Th17/Treg related molecules in gastric cancer tissues

BACKGROUND/AIMS

The function of regulatory T cells (Treg) and helper T cells 17 (Th17) related indexes, such as interleukin (IL)-6, IL-17, transforming growth factor (TGF)-β1, and forkhead box protein 3(FoxP3) in gastric adenocarcinoma tissues remains undefined. We investigated and analyzed the relevance of the proteins with the clinicopathological characteristics and the interactions among them in gastric cancer.

MATERIALS AND METHODS

A total 68 gastric cancer patients and 40 healthy controls were enrolled. Immunohistochemistry (IHC) as well as quantitative real-time reverse transcription- polymerase chain reaction (RT-PCR) was used to determine the expression levels of IL-6, TGF-β1, IL-17, and FoxP3 in the prepared tissues. Statistical analysis included ANOVA and chi-square test.

RESULTS

The expression levels of IL-6, IL-17, FoxP3, and TGF-β1 had significantly increased in cancer tissues compared to controls. Clinical staging of gastric cancer were correlated with the rise of IL-6, IL-17, FoxP3, and TGF-β1 levels expressed in cancer tissues. The expression level of TGF-β1 and IL-6 was positively related to that of IL-17 and FoxP3, similar to FoxP3 and IL-17 in gastric cancer tissues.

CONCLUSION

IL-6, TGF-β1, FoxP3, and IL-17 may promote the progression of gastric cancer individually or jointly and have complex interactions.

BET Bromodomain Inhibition Cooperates with PD-1 Blockade to Facilitate Antitumor Response in Kras-Mutant Non-Small Cell Lung Cancer

KRAS mutation is present in approximately 30% of human lung adenocarcinomas. Although recent advances in targeted therapy have shown great promise, effective targeting of KRAS remains elusive, and concurrent alterations in tumor suppressors render KRAS-mutant tumors even more resistant to existing therapies. Contributing to the refractoriness of KRAS-mutant tumors are immunosuppressive mechanisms, such as increased presence of suppressive regulatory T cells (Treg) in tumors and elevated expression of the inhibitory receptor PD-1 on tumor-infiltrating T cells. Treatment with BET bromodomain inhibitors is beneficial for hematologic malignancies, and they have Treg-disruptive effects in a non-small cell lung cancer (NSCLC) model. Targeting PD-1-inhibitory signals through PD-1 antibody blockade also has substantial therapeutic impact in lung cancer, although these outcomes are limited to a minority of patients. We hypothesized that the BET bromodomain inhibitor JQ1 would synergize with PD-1 blockade to promote a robust antitumor response in lung cancer. In the present study, using Kras^+/LSL-G12D ; Trp53^L/L (KP) mouse models of NSCLC, we identified cooperative effects between JQ1 and PD-1 antibody. The numbers of tumor-infiltrating Tregs were reduced and activation of tumor-infiltrating T cells, which had a T-helper type 1 (Th1) cytokine profile, was enhanced, underlying their improved effector function. Furthermore, lung tumor-bearing mice treated with this combination showed robust and long-lasting antitumor responses compared with either agent alone, culminating in substantial improvement in the overall survival of treated mice. Thus, combining BET bromodomain inhibition with immune checkpoint blockade offers a promising therapeutic approach for solid malignancies such as lung adenocarcinoma. Cancer Immunol Res; 6(10); 1234-45. ©2018 AACR.

Dipeptidyl peptidase-4(DPP-4) inhibitors: promising new agents for autoimmune diabetes

Dipeptidyl peptidase-4 (DPP-4) inhibitors constitute a novel class of anti-diabetic agents confirmed to improve glycemic control and preserve β-cell function in type 2 diabetes. Three major large-scale studies, EXAMINE, SAVOR-TIMI 53, and TECOS, have confirmed the cardiovascular safety profile of DPP-4 inhibitors. Based on these results, DPP-4 inhibitors have gained widespread use in type 2 diabetes treatment. It is currently unknown, however, whether DPP-4 inhibitors have similar therapeutic efficacy against autoimmune diabetes. Several in vitro and in vivo studies have addressed this issue, but the results remain controversial. In this review, we summarize experimental findings and preliminary clinical trial results, and identify potentially effective immune modulation targets of DPP-4 inhibitors for autoimmune diabetes.

Recent advances in CD8+ regulatory T cell research

Various subgroups of CD8⁺ T lymphocytes do not only demonstrate cytotoxic effects, but also serve important regulatory roles in the body's immune response. In particular, CD8⁺ regulatory T cells (CD8⁺ Tregs), which possess important immunosuppressive functions, are able to effectively block the overreacting immune response and maintain the body's immune homeostasis. In recent years, studies have identified a small set of special CD8⁺ Tregs that can recognize major histocompatibility complex class Ib molecules, more specifically Qa-1 in mice and HLA-E in humans, and target the self-reactive CD4⁺ T ce lls. These findings have generated broad implications in the scientific community and attracted general interest to CD8⁺ Tregs. The present study reviews the recent research progress on CD8⁺ Tregs, including their origin, functional classification, molecular markers and underlying mechanisms of action.

Comparative Analysis of the Regulatory T Cells Dynamics in Peripheral Blood in Human and Porcine Polytrauma

Background

Severely injured patients experience substantial immunological stress in the aftermath of traumatic insult, which often results in systemic immune dysregulation. Regulatory T cells (Treg) play a key role in the suppression of the immune response and in the maintenance of immunological homeostasis. Little is known about their presence and dynamics in blood after trauma, and nothing is known about Treg in the porcine polytrauma model. Here, we assessed different subsets of Treg in trauma patients (TP) and compared those to either healthy volunteers (HV) or data from porcine polytrauma.

Methods

Peripheral blood was withdrawn from 20 TP with injury severity score (ISS) ≥16 at the admittance to the emergency department (ED), and subsequently on day 1 and at day 3. Ten HV were included as controls (ctrl). The porcine polytrauma model consisted of a femur fracture, liver laceration, lung contusion, and hemorrhagic shock resulting in an ISS of 27. After polytrauma, the animals underwent resuscitation and surgical fracture fixation. Blood samples were withdrawn before and immediately after trauma, 24 and 72 h later. Different subsets of Treg, CD4+CD25+, CD4+CD25+FoxP3+, CD4+CD25+CD127-, and CD4+CD25+CD127-FoxP3+ were characterized by flow cytometry.

Results

Absolute cell counts of leukocytes were significantly increasing after trauma, and again decreasing in the follow-up in human and porcine samples. The proportion of human Treg in the peripheral blood of TP admitted to the ED was lower when compared to HV. Their numbers did not recover until 72 h after trauma. Comparable data were found for all subsets. The situation in the porcine trauma model was comparable with the clinical data. In porcine peripheral blood before trauma, we could identify Treg with the typical immunophenotype (CD4+CD25+CD127-), which were virtually absent immediately after trauma. Similar to the human situation, most of these cells expressed FoxP3, as assessed by intracellular FACS stain.

Conclusion

Despite minor percental differences in the recovery of Treg populations after trauma, our findings show a comparable decrease of Treg early after polytrauma, and strengthen the immunological significance of the porcine polytrauma model. Furthermore, the Treg subpopulation CD4+CD25+CD127- was characterized in porcine samples.

Transcriptional regulation and development of regulatory T cells

Regulatory T (Treg) cells are a distinct subset of CD4⁺ T cells. Instead of triggering adaptive immunity, they suppress immune responses. Small numbers of Treg cells reside within lymphoid organs and peripheral tissues, but their contribution to immune tolerance is so significant that defects in Treg cell function cause catastrophic immune disorders. Since they were first discovered 20 years ago, efforts have been made to understand the differences in developmental processes between Treg cells and conventional T cells that determine the ultimate fate of the overall T-cell population. Transcription factor Foxp3 is crucial for Treg cell differentiation, but it is not the whole story. Owing to recent advances in Treg cell research, we are now on the verge of appreciating the comprehensive mechanisms underlying Treg cell generation. Here, we discuss major discoveries, active study topics and remaining questions regarding Treg cell development.

Therapeutic application of T regulatory cells in composite tissue allotransplantation

With growing number of cases in recent years, composite tissue allotransplantation (CTA) has been improving the quality of life of patient who seeks reconstruction and repair of damaged tissues. Composite tissue allografts are heterogeneous. They are composed of a variety of tissue types, including skin, muscle, vessel, bone, bone marrow, lymph nodes, nerve, and tendon. As a primary target of CTA, skin has high antigenicity with a rich repertoire of resident cells that play pivotal roles in immune surveillance. In this regard, understanding the molecular mechanisms involved in immune rejection in the skin would be essential to achieve successful CTA. Although scientific evidence has proved the necessity of immunosuppressive drugs to prevent rejection of allotransplanted tissues, there remains a lingering dilemma due to the lack of specificity of targeted immunosuppression and risks of side effects. A cumulative body of evidence has demonstrated T regulatory (Treg) cells have critical roles in induction of immune tolerance and immune homeostasis in preclinical and clinical studies. Presently, controlling immune susceptible characteristics of CTA with adoptive transfer of Treg cells is being considered promising and it has drawn great interests. This updated review will focus on a dominant form of Treg cells expressing CD4+CD25+ surface molecules and a forkhead box P3 transcription factor with immune tolerant and immune homeostasis activities. For future application of Treg cells as therapeutics in CTA, molecular and cellular characteristics of CTA and immune rejection, Treg cell development and phenotypes, Treg cell plasticity and stability, immune tolerant functions of Treg cells in CTA in preclinical studies, and protocols for therapeutic application of Treg cells in clinical settings are addressed in this review. Collectively, Treg cell therapy in CTA seems feasible with promising perspectives. However, the extreme high immunogenicity of CTA warrants caution.

Ex vivo-expanded baboon CD39 + regulatory T cells prevent rejection of porcine islet xenografts in NOD-SCID IL-2rγ-/- mice reconstituted with baboon peripheral blood mononuclear cells

BACKGROUND

A high immunosuppressive burden is required for long-term islet xenograft survival in non-human primates even using genetically modified donor pigs.

AIMS

We aimed to investigate the capacity of baboon regulatory T cells (Treg) to suppress islet xenograft rejection, thereby developing a potential immunoregulatory or tolerance therapy that could be evaluated in NHP models of xenotransplantation.

MATERIALS & METHODS

Baboon Treg expanded with stimulation by porcine peripheral blood mononuclear cells (PBMC) were characterized by cell phenotyping and suppressive activity assays in vitro. Their function in vivo was evaluated in neonatal porcine islet cell clusters (NICC) transplanted NOD-SCID IL-2rγ-/- (NSG) mice receiving baboon PBMC alone or with expanded autologous Treg.

RESULTS

The majority of expanded Treg coexpressed Foxp3 and CD39 and were highly suppressive of the baboon anti-pig xenogeneic T cell response in vitro. Reconstitution of mice with baboon PBMC alone resulted in NICC xenograft rejection within 35 days. Cotransfer with baboon PBMC and Treg prolonged islet xenograft survival beyond 100 days, correlating with Treg engraftment, intragraft CD39 and Foxp3 gene expression, and reduced graft infiltrating effector T cells and reduced interferon-γ production.

DISCUSSION & CONCLUSION

Our data supports the capacity of ex vivo expanded CD39+ baboon Treg to suppress islet xenograft rejection in primatized mice, suggesting it has potential as an adjunctive immunotherapy in preclinical NHP models of xenotransplantation.

Suppression by human FOXP3 + regulatory T cells requires FOXP3-TIP60 interactions

Targeting the FOXP3-TIP60 interaction may modulate T reg activity in IPEX and other autoimmune and inflammatory diseases.

Enhancement of scutellarin oral delivery efficacy by vitamin B12-modified amphiphilic chitosan derivatives to treat type II diabetes induced-retinopathy

BACKGROUND

Diabetic retinopathy is the most common complication in diabetic patients relates to high expression of VEGF and microaneurysms. Scutellarin (Scu) turned out to be effective against diabetes related vascular endothelial cell dysfunction. However, its clinical applications have been limited by its low bioavailability. In this study, we formulated and characterized a novel intestinal target nanoparticle carrier based on amphiphilic chitosan derivatives (Chit-DC-VB12) loaded with scutellarin to enhance its bioavailability and then evaluated its therapeutic effect in experimental diabetic retinopathy model.

RESULTS

Chit-DC-VB12 nanoparticles showed low toxicity toward the human colon adenocarcinoma (Caco-2) cells and zebra fish within concentration of 250 μg/ml, owing to good biocompatibility of chitosan. The scutellarin-loaded Chit-DC-VB12 nanoparticles (Chit-DC-VB12-Scu) were then prepared by self-assembly in aqueous solution. Scanning electron microscopy and dynamic light scattering analysis indicated that the Chit-DC-VB12-Scu nanoparticles were spherical particles in the sizes ranging from 150 to 250 nm. The Chit-DC-VB12-Scu nanoparticles exhibited high permeation in Caco-2 cell, indicated it could be beneficial to be absorbed in humans. We also found that Chit-DC-VB12 nanoparticles had a high cellular uptake. Bioavailability studies were performed in Sprague-Dawley rats, which present the area under the curve of scutellarin of Chit-DC-VB12-Scu was two to threefolds greater than that of free scutellarin alone. Further to assess the therapeutic efficacy of diabetic retinopathy, we showed Chit-DC-VB12-Scu down-regulated central retinal artery resistivity index and the expression of angiogenesis proteins (VEGF, VEGFR2, and vWF) of retinas in type II diabetic rats.

CONCLUSIONS

Chit-DC-VB12 nanoparticles loaded with scutellarin have better bioavailability and cellular uptake efficiency than Scu, while Chit-DC-VB12-Scu nanoparticles alleviated the structural disorder of intraretinal neovessels in the retina induced by diabetes, and it also inhibited the retinal neovascularization via down-regulated the expression of angiogenesis proteins. In conclusion, the Chit-DC-VB12 nanoparticles enhanced scutellarin oral delivery efficacy and exhibited potential as small intestinal target promising nano-carriers for treatment of type II diabetes induced-retinopathy.

Peripherally Generated Foxp3+ Regulatory T Cells Mediate the Immunomodulatory Effects of IVIg in Allergic Airways Disease

IVIg is widely used as an immunomodulatory therapy. We have recently demonstrated that IVIg protects against airway hyperresponsiveness (AHR) and inflammation in mouse models of allergic airways disease (AAD), associated with induction of Foxp3⁺ regulatory T cells (Treg). Using mice carrying a DTR/EGFP transgene under the control of the Foxp3 promoter (DEREG mice), we demonstrate in this study that IVIg generates a de novo population of peripheral Treg (pTreg) in the absence of endogenous Treg. IVIg-generated pTreg were sufficient for inhibition of OVA-induced AHR in an Ag-driven murine model of AAD. In the absence of endogenous Treg, IVIg failed to confer protection against AHR and airway inflammation. Adoptive transfer of purified IVIg-generated pTreg prior to Ag challenge effectively prevented airway inflammation and AHR in an Ag-specific manner. Microarray gene expression profiling of IVIg-generated pTreg revealed upregulation of genes associated with cell cycle, chromatin, cytoskeleton/motility, immunity, and apoptosis. These data demonstrate the importance of Treg in regulating AAD and show that IVIg-generated pTreg are necessary and sufficient for inhibition of allergen-induced AAD. The ability of IVIg to generate pure populations of highly Ag-specific pTreg represents a new avenue to study pTreg, the cross-talk between humoral and cellular immunity, and regulation of the inflammatory response to Ags.

Analyses of regulatory CD4+ CD25+ FOXP3+ T cells and observations from peripheral T cell subpopulation markers during the development of type 1 diabetes in children

Our aim was to study whether the aberrant amount or function of regulatory T cells is related to the development of type 1 diabetes (T1D) in children. We also set out to investigate the balance of different T cell subtype markers during the T1D autoimmune process. Treg cells were quantified with flow cytometric assay, and the suppression capacity was analysed with a carboxyfluorescein succinimidyl ester (CFSE)-based T cell suppression assay in children in various phases of T1D disease process and in healthy autoantibody-negative control children. The mRNA expression of different T cell subpopulation markers was analysed with real-time qPCR method. The proportion and suppression capacity of regulatory T cells were similar in seroconverted children at an early stage of beta cell autoimmunity and also in children with T1D when compared to healthy and autoantibody-negative children. Significant differences were observed in the mRNA expression of different T cell subpopulation markers in prediabetic children with multiple (≥ 2) autoantibodies and in children with newly diagnosed T1D when compared to the control children. In conclusion, there were no quantitative or functional differences in regulatory T cells between the case and control groups in any phase of the autoimmune process. Decreased mRNA expression levels of T cell subtype markers were observed in children with multiple islet autoantibodies and in those with newly diagnosed T1D, probably reflecting an exhaustion of the immune system after the strong immune activation during the autoimmune process or a generally aberrant immune response related to the progression of the disease.

Categorical Analysis of Human T Cell Heterogeneity with One-Dimensional Soli-Expression by Nonlinear Stochastic Embedding

Rapid progress in single-cell analysis methods allow for exploration of cellular diversity at unprecedented depth and throughput. Visualizing and understanding these large, high-dimensional datasets poses a major analytical challenge. Mass cytometry allows for simultaneous measurement of >40 different proteins, permitting in-depth analysis of multiple aspects of cellular diversity. In this article, we present one-dimensional soli-expression by nonlinear stochastic embedding (One-SENSE), a dimensionality reduction method based on the t-distributed stochastic neighbor embedding (t-SNE) algorithm, for categorical analysis of mass cytometry data. With One-SENSE, measured parameters are grouped into predefined categories, and cells are projected onto a space composed of one dimension for each category. In contrast with higher-dimensional t-SNE, each dimension (plot axis) in One-SENSE has biological meaning that can be easily annotated with binned heat plots. We applied One-SENSE to probe relationships between categories of human T cell phenotypes and observed previously unappreciated cellular populations within an orchestrated view of immune cell diversity. The presentation of high-dimensional cytometric data using One-SENSE showed a significant improvement in distinguished T cell diversity compared with the original t-SNE algorithm and could be useful for any high-dimensional dataset.

MicroRNA-21 deficiency protects from lupus-like autoimmunity in the chronic graft-versus-host disease model of systemic lupus erythematosus

MicroRNAs (miRNAs) are small, non-coding RNAs that regulate gene expression primarily at the post-transcriptional level. Emerging evidence supports a regulatory role for miRNAs in the immune response and autoimmunity. In this work, we investigated the implication of miR-21 in the experimentally inducible bm12→B6 cGVHD model of systemic lupus erythematosus (SLE). cGVHD host mice deficient in miR-21 show a 2-fold reduction in splenomegaly, significantly reduced autoantibody titers and down-regulated components of the CD40:CD40L and CD28:CD80/86 co-stimulation pathways. Furthermore, we demonstrate that miR-21-deficient hosts have reduced CD4(+) IL-17(+) cell populations and an expanded CD4(+) CD25(+) FoxP3(+) cell compartment. We propose that miR-21 has a pluripotent role, serving to link distinct lymphocyte signaling pathways and acting as a "rheostat" for signals that promote B and T cell activation in lupus. Collectively, our experiments demonstrate that miR-21 deficiency in cGVHD host mice is sufficient to protect from lupus-like autoimmunity.

The Molecular Control of Regulatory T Cell Induction

Regulatory T cells (Tregs) are characterized by the expression of the master transcription factor forkhead box P3 (Foxp3). Although Foxp3 expression is widely used as a marker of the Treg lineage, recent data show that the Treg fate is determined by a multifactorial signaling pathway, involving cytokines, nuclear factors, and epigenetic modifications. Foxp3 expression and the Treg phenotype can be acquired by T cells in the periphery, illustrating that the Treg fate is not necessarily conferred during thymic development. The two main Treg populations in vivo, thymic Tregs and peripheral Tregs, differ in the pathways followed for their maturation. This chapter discusses the molecular control of Treg induction, in the thymus as well as the periphery.

Induction of Regulatory T Cells by Intravenous Immunoglobulin: A Bridge between Adaptive and Innate Immunity

Intravenous immunoglobulin (IVIg) is a polyclonal immunoglobulin G preparation with potent immunomodulatory properties. The mode of action of IVIg has been investigated in multiple disease states, with various mechanisms described to account for its benefits. Recent data indicate that IVIg increases both the number and the suppressive capacity of regulatory T cells, a subpopulation of T cells that are essential for immune homeostasis. IVIg alters dendritic cell function, cytokine and chemokine networks, and T lymphocytes, leading to development of regulatory T cells. The ability of IVIg to influence Treg induction has been shown both in animal models and in human diseases. In this review, we discuss data on the potential mechanisms contributing to the interaction between IVIg and the regulatory T-cell compartment.