Foxp3 is critical for human natural CD4+CD25+ regulatory T cells to suppress alloimmune response

Ectopic FOXP3 Expression in Combination with TGF-β1 and IL-2 Stimulation Generates Limited Suppressive Function in Human Primary Activated Thymocytes Ex Vivo

Regulatory T cells (Tregs), which are characterized by the expression of the transcription factor forkhead box P3 (FOXP3), are the main immune cells that induce tolerance and are regulators of immune homeostasis. Natural Treg cells (nTregs), described as CD4⁺CD25⁺FOXP3⁺, are generated in the thymus via activation and cytokine signaling. Transforming growth factor beta type 1 (TGF-β1) is pivotal to the generation of the nTreg lineage, its maintenance in the thymus, and to generating induced Treg cells (iTregs) in the periphery or in vitro arising from conventional T cells (Tconvs). Here, we tested whether TGF-β1 treatment, associated with interleukin-2 (IL-2) and CD3/CD28 stimulation, could generate functional Treg-like cells from human thymocytes in vitro, as it does from Tconvs. Additionally, we genetically manipulated the cells for ectopic FOXP3 expression, along with the TGF-β1 treatment. We demonstrated that TGF-β1 and ectopic FOXP3, combined with IL-2 and through CD3/CD28 activation, transformed human thymocytes into cells that expressed high levels of Treg-associated markers. However, these cells also presented a lack of homogeneous suppressive function and an unstable proinflammatory cytokine profile. Therefore, thymocyte-derived cells, activated with the same stimuli as Tconvs, were not an appropriate alternative for inducing cells with a Treg-like phenotype and function.

Effect of TGF-β1 on blood CD4+CD25high regulatory T cell proliferation and Foxp3 expression during non-small cell lung cancer blood metastasis

Metastatic circulating tumor cells in non-small cell lung cancer (NSCLC) metastasis have been reported to be associated with an immune response. The present study aimed to provide a theoretical basis for the immunomodulatory processes during NSCLC blood metastasis. NSCLC blood and normal peripheral blood mononuclear cells (PBMCs) were collected. The quantity of cluster of differentiation (CD)4⁺CD25^high regulatory T (Treg) cells and the intracellular forkhead box protein 3 (Foxp3) expression in CD4⁺CD25^high Treg cells were determined by flow cytometry. Furthermore, the effect of transforming growth factor β1 (TGF-β1) on NSCLC blood CD4⁺CD25⁺ Treg cell proliferation was explored by activating blood mononuclear cells with an anti-CD3 monoclonal antibody, interleukin-2 and different doses of TGF-β1. Reverse transcription-quantitative polymerase chain reaction assays were used to detect the mRNA expression of Foxp3. Carboxyfluorescein succinimidyl ester staining was used to analyze the proliferation dynamics of lymphocyte subsets. Results indicate that the proportion of CD4⁺ T cells in the blood of patients with NSCLC was significantly higher compared with normal peripheral blood (P<0.01). Foxp3 expression in NSCLC blood Treg cells was significantly decreased compared with normal peripheral blood (P<0.01). NSCLC blood mononuclear cells treated with TGF-β1 at 1, 5 and 25 ng/ml significantly induced Foxp3 expression in CD4⁺CD25⁺ Treg cells compared with the control group (P<0.05). The proportion of CD4⁺CD25⁺ Treg and CD8⁺ T cells were elevated in generation 6, 7, 8 after 6 days of TGF-β1 treatment compared with untreated cells. The proportion of CD4⁺CD25⁺ Treg and CD8⁺ T cells were elevated in generation 8, 9 and with TGF-β1 treatment after 8 days compared with untreated cells. These results indicate that CD4⁺CD25⁺ Treg cells proliferate at a greater rate compared with CD8⁺ T cells after 4, 6 or 8 days of treatment. The proportion of CD4⁺CD25^high Treg cells in NSCLC blood was significantly higher (P<0.05) compared with normal peripheral blood. The number of Foxp3⁺ T cells was significantly lower (P<0.05) compared with normal peripheral blood. The data presented in this study suggest that NSCLC blood CD4⁺CD25^high Treg cells are functionally immature and that TGF-β1 may promote maturation.

New Insights into Regulatory T Cells: Exosome- and Non-Coding RNA-Mediated Regulation of Homeostasis and Resident Treg Cells

Regulatory T (Treg) cells are a group of cells that are heterogeneous in origin and in functional activity. Treg cells comprise a necessary balance to adaptive immune responses. As key regulators of self-tolerance, Treg cells have been involved in a series of pathologic processes and considered as therapeutic targets. Here, we summarize recent research regarding Treg cell origins and their functional classification, highlight the role of exosomes and non-coding RNA in modulating Treg cell homeostasis, and discuss the current understanding of resident Treg cells.

Treg cells as potential cellular targets for functionalized nanoparticles in cancer therapy

Treg cell-mediated immune suppression appears to represent a significant barrier to effective anticancer immune responses and their inactivation or removal is viewed as a potential therapeutic approach. Although suitable tools for selective Treg cell manipulation in man are missing, their number and function can be altered by a number of drugs and biologicals and by reprogramming tumor-infiltrating antigen presenting cells. Nanoparticles offer exceptional new options in drug and gene delivery by prolonging the circulation time of their cargo, protecting it from degradation and promoting its local accumulation in cells and tissues. In tumor therapy, the use of nanoparticles is expected to overcome limitations in drug delivery and provide novel means for cell-specific functional alteration. In this perspective, we summarize strategies suitable for interference with Treg-mediated suppression, discuss the potential use of nanoparticles for this purpose and identify additional, unexplored opportunities.

Platelet-cytokine Complex Suppresses Tumour Growth by Exploiting Intratumoural Thrombin-dependent Platelet Aggregation

Tumours constitute unique microenvironments where various blood cells and factors are exposed as a result of leaky vasculature. In the present study, we report that thrombin enrichment in B16F10 melanoma led to platelet aggregation, and this property was exploited to administer an anticancer cytokine, interferon-gamma induced protein 10 (IP10), through the formation of a platelet-IP10 complex. When intravenously infused, the complex reached platelet microaggregates in the tumour. The responses induced by the complex were solely immune-mediated, and tumour cytotoxicity was not observed. The complex suppressed the growth of mouse melanoma in vivo, while both platelets and the complex suppressed the accumulation of FoxP3⁺ regulatory T cells in the tumour. These results demonstrated that thrombin-dependent platelet aggregation in B16F10 tumours defines platelets as a vector to deliver anticancer cytokines and provide specific treatment benefits.

Not just for tumor targeting: unmet medical needs and opportunities for nanomedicine

During the last 3 decades, nanomedicines have provided novel opportunities to improve the delivery of chemotherapeutics in cancer therapy effectively. However, many principles learnt from there have the potential to be transferred to other diseases. This perspective article, on the one hand, critically reflects the limitations of nanomedicines in tumor therapy and, on the other hand, provides alternative examples of nanomedicinal applications in immunotherapy, noninvasive drug deliveries across epithelial barriers and strategies to combat intra- and extra-cellular bacterial infections. Looking ahead, access to highly complex nanoparticular delivery vehicles given nowadays may allow further improved therapeutic concepts against several diseases in the future too.

Activated Conventional T-Cells Are Present in Langerhans Cell Histiocytosis Lesions Despite the Presence of Immune Suppressive Cytokines

Langerhans cell histiocytosis (LCH) lesions are characterized by neoplastic CD1a(+)/Langerin(+) histiocytes (LCH-cells) and display many features of chronic inflammation. Cancer cells can escape immune-surveillance through intra-tumoral secretion of immune-suppressive cytokines. We therefore studied by immunohistochemistry the local cytokine milieu and phenotypic characteristics of T-cells and LCH-cells present in LCH lesions collected from 25 therapy naïve patients. LCH biopsies predominantly expressed interleukin-10 (IL-10) (10/25), transforming growth factor-beta (TGF-β) (9/25), or both cytokines (6/25). The absolute number of CD3(+)T-cells and the CD3(+)FOXP3(-) conventional cell (T-CONV) versus the CD3(+)FOXP3(+) regulatory T-cell (T-REG) was comparable for each suppressive cytokine profile (5:1). IL-10-expressing lesions contained, however, a higher proportion of T-CONV expressing the activation markers CD25 98% (38%-100%) and inducible costimulatory molecule (ICOS) 86% (47%-100%) than lesions wherein solely TGF-β was detected (CD25(+) 20% (6%-54%); ICOS(+) 29% (7%-51%)). Virtually all T-REG expressed CD25 and ICOS in IL-10 lesions, whereas TGF-β(+) lesions contained a lower proportion of ICOS(+) T-REG (P=0.05). IL-10(+) lesions contained more LCH-cells expressing high intensity of ICOS ligand (ICOSL) compared with TGF-β(+) lesions (P=0.03). ICOS expression by lesion-infiltrating T-CONV and T-REG positively correlated to the extent of ICOSL expression by LCH-cells (P=0.004). Our study points out that the combined detection of interlesional IL-10 and ICOSL expression by LCH-cells is associated with the highest prevalence of activated T-CONV. Immune profiling of LCH-affected tissues obtained at the time of diagnosis may set the stage for the development of new types of therapies, which aim at local boosting of immune cells that recognize and eliminate neoplastic LCH-cells.

Extension of the CD4⁺Foxp3⁺CD25(-/low) regulatory T-cell subpopulation in type 1 diabetes mellitus

Regulatory T-cells (Treg) have a crucial role in limiting physiologic autoreactivity. Foxp3 is a master regulator transcription factor of Treg differentiation and active Treg cells express high levels of IL-2 receptor α-chain (CD25). The aim of our study was to assess the key markers of Treg cell function in type 1 diabetic (T1DM) and control subjects by flow cytometry. The proportion of CD25(-/low) cells among CD4(+)Foxp3(+) Treg cells was higher in T1DM patients that might suggest a shifted proportion of the incomplete/reserve and the fully active (CD4(+)Foxp3(+)CD25(+)) Treg cell subpopulations in T1DM, similarly to other Th1-mediated autoimmune diseases. In addition to the decreased expression of CD25 and CTLA-4 in T1DM patients, a positive correlation was observed between the CD25 expression on CD4(+) and the CTLA-4 expression in CD8(-) T-lymphocytes both in the T1DM and in the healthy control group. Our results suggest an impaired balance of CD25(+) and CD25(-/low) Treg cells in T1DM which might reflect a decreased late phase peripheral Treg activation even in patients with a mean disease duration of more than a decade.

Special role of Foxp3 for the specifically altered microRNAs in Regulatory T cells of HCC patients

Background

Regulatory T cells (Tregs) exhibit functional abnormalities in the context of hepatocellular carcinoma (HCC). The microRNAs (miRNAs) are identified as the key modulators in Tregs. This study was to explore whether the expression profiles of miRNAs of Tregs were different in HCC-activated Tregs and whether Foxp3 had special effects on them.

Methods

We isolated HCC-activated Tregs from mice bearing HCC and compared the expression profiles of miRNAs between HCC-activated Tregs and control Tregs by microarray. RNA interference against Foxp3 was also performed through transfection of synthetic siRNAs to Tregs for analyzing the effect of Foxp3 on the expression of miRNAs. Tregs isolated from HCC patients (n = 12) and healthy controls (n = 7) were used for validation of the differentially expressed miRNAs. Finally, bioinformatic analysis was applied to infer their possible roles.

Results

We found nine specifically altered miRNAs in HCC-activated Tregs from the murine model. After transfection with siRNAs against Foxp3, control Tregs showed obvious reduction of Foxp3 and five miRNAs were significantly changed; HCC-activated Tregs exhibited a slight reduction of Foxp3 with three miRNAs significantly changed. Tregs from HCC patients and healthy controls finally confirmed the up-regulation of four miRNAs (hsa-miR-182-5p, hsa-miR-214-3p, hsa-miR-129-5p and hsa-miR-30b-5p). Following bioinformatic analysis suggested these altered miRNAs would target eight important signaling pathways that could affect the functions of Tregs.

Conclusions

Our studies provided the first evidence that Tregs in HCC had the specifically altered expression of miRNAs, which was affected by Foxp3. These results are useful both in finding new biomarkers and in further exploring the functions of Tregs in HCC patients.

Advances in siRNA delivery to T-cells: potential clinical applications for inflammatory disease, cancer and infection

The specificity of RNAi and its ability to silence ‘undruggable’ targets has made inhibition of gene expression in T-cells with siRNAs an attractive potential therapeutic strategy for the treatment of inflammatory disease, cancer and infection. However, delivery of siRNAs into primary T-cells represents a major hurdle to their use as potential therapeutic agents. Recent advances in siRNA delivery through the use of electroporation/nucleofection, viral vectors, peptides/proteins, nanoparticles, aptamers and other agents have now enabled efficient gene silencing in primary T-cells both in vitro and in vivo. Overcoming such barriers in siRNA delivery offers exciting new prospects for directly targeting T-cells systemically with siRNAs, or adoptively transferring T-cells back into patients following ex vivo manipulation with siRNAs. In the present review, we outline the challenges in delivering siRNAs into primary T-cells and discuss the mechanism and therapeutic opportunities of each delivery method. We emphasize studies that have exploited RNAi-mediated gene silencing in T-cells for the treatment of inflammatory disease, cancer and infection using mouse models. We also discuss the potential therapeutic benefits of manipulating T-cells using siRNAs for the treatment of human diseases.

Anti-TNF-α therapy improves Treg and suppresses Teff in patients with rheumatoid arthritis

Anti-TNF-α therapies have been applied in RA treatment, but the regulatory effect of the drug on immune system is not clear. In this study, we included 33 active RA patients and divided them into two groups. One group received anti-TNF-α mAb+methotrexate for 24 weeks, the other group got placebo+methotrexate for the first 12 weeks and anti-TNF-α mAb+methotrexate for another 12 weeks. Circulatory regulatory T cell (Treg) and effector T cell (Teff) frequency was analyzed pre-therapy and week 12 and week 24 for both group patients by flowcytometry. Our results indicated significantly elevated Treg and decreased Teff at week 24 compared with pre-therapy and week 12 for both group patients, and a little higher Treg and lower Teff frequency in anti-TNF-α therapy group than in placebo therapy patients. Our results demonstrated anti-TNF-α therapy has regulatory effect on immune system of RA patients by promoting Treg proportion increase and suppressing Teff.

An increase of Treg cells in the peripheral blood is associated with a better in vitro fertilization treatment outcome

PROBLEM

The objective of this study was to determine whether there was any association between the peripheral blood CD4(+) CD25(+) Foxp3(+) regulatory T cells (Treg cells) and implantation success in patients undergoing in vitro fertilization (IVF) treatment.

METHOD OF STUDY

Prospective observational study of 101 randomly selected women who underwent IVF treatment for tubal factor from May 2011 to June 2011. The percentage of peripheral blood Treg cells and the expression levels of Foxp3 and CTLA4 mRNA in peripheral blood mononuclear cells (PBMCs) were recorded and their relations to IVF treatment outcomes were analyzed.

RESULTS

Treg cells were significantly elevated in the pregnant group ( P = 0.03). The expression level of Foxp3 mRNA in PBMCs from pregnant group also significantly increased ( P = 0.02). A receiver operating characteristic analysis (area under curve = 0.631) found that those women with Treg cells >0.6%, the pregnancy rate and live birth rate were much higher as compared to women with Treg cells below this level ( P < 0.05). An increase of Treg cells in the peripheral blood was associated with a better IVF treatment outcome (OR 4.3, 95% CI = 1.76-10.48), with a sensitivity of 64%, specificity of 71%.

CONCLUSION

An elevated level of circulating Treg cells was associated with increased rates of pregnancy and live birth in IVF treatment.