MicroRNAs are implicated in the suppression of CD4CD25 conventional T cell proliferation by CD4CD25 regulatory T cells

CD4⁺CD25⁺ regulatory T cells (Tregs) are critical for sustaining immunological homeostasis. CD4⁺CD25⁻ conventional T cells (Tcons) are the progenitors of populations including Th1, Th2, Th17, Tfh, and Treg cells. Suppression of Tcons proliferation by Tregs requires cell–cell contact and/or is mediated by immunosuppressive soluble factors. However, upon receiving suppressive signals from Tregs, the exact molecular responses in Tcons remain elusive. Here, by using microRNA (miRNA) microarray preliminary screening and quantitative RT-PCR (qRT-PCR) validation, we showed that paralleled with the suppression of the Tcons proliferation, miR-146a was induced but miR-106b and miR-21 were reduced in Tcons upon receiving suppressive signals from Tregs. Moreover, our results showed that either increase of miR-146a or decrease of miR-106b and miR-21 by using miRNA mimics or inhibitors in Tcons significantly enhanced the suppression triggered by Tregs. However, decrease of miR-146a or increase of miR-106b and miR-21 in Tcons impaired the suppression triggered by Tregs. Collectively, our findings demonstrate the roles of miR-146a, miR-106b and miR-21 in Tcons in regulating Treg-triggered immune-suppression.     

Galectin-1 reduction and changes in T regulatory cells may play crucial roles in patients with unexplained recurrent spontaneous abortion

To investigate the changes of Galectin-1 and T-lymphocyte phenotypes in unexplained recurrent spontaneous abortion (URSA). Totally 60 participants were recruited and divided into 3 groups in average: pregnant patients with URSA (URSA group), normal early pregnant women with induced abortion (IA group) and normal non-pregnant women (control group). After the tissue and blood sample were collected, Galectin-1 was measured using enzyme-linked immunosorbent assay. Then the proportion of T regulatory cells was determined by flow cytometry. The expression levels of Galectin-1 in IA group and URSA group was significantly higher than that in the control group (24.30 ± 3.06 and 6.23 ± 2.41 vs. 1.30 ± 0.66, P < 0.05). Besides, the expression level of Galectin-1 in URSA group was lower than that in IA group (P < 0.05). The percentage of CD4⁺CD25⁺Foxp3⁺ Tregs was lower in URSA group than IA group (0.77 ± 0.31 vs. 1.00 ± 0.35, P < 0.05) and the ratio of CD4⁺CD25⁺Foxp3⁺/CD4⁺ in URSA group was also obviously lower than that in IA and control group (P < 0.05). Galectin-1 and CD4⁺CD25⁺Foxp3⁺ may play essential roles in maintaining a normal pregnancy and their reduction may involve in the pathogenesis of URSA.     

Effects of fentanyl anesthesia and sufentanil anesthesia on regulatory T cells frequencies

Background: CD4⁺CD25⁺Foxp3⁺ regulatory T cells (Tregs) can inhibit anti-tumor immune responses and opioids were also immunosuppressive. We set out to compare the effects of sufentanil and fentanyl on Tregs frequencies both in vitro and in breast cancer (BC) patients undergoing eradicative operation. Methods: PBMCs from 12 BC patients were activated in vitro in the presence of fentanyl or sufentanil. The percentage of Tregs was detected by flow cytometry after seven days culture. Other 38 patients who underwent eradicative operation were prospectively randomized to sufentanil anesthesia and fentanyl anesthesia. Blood samples were collected for Tregs quantification by flow cytometry analysis and for Foxp3 mRNA expression by RT-PCR, at 10 min before anesthesia (D0), 24h (D1), and 168 h (D7) after the operation respectively. Results: Activation of PBMCs in the presence of either fentanyl or sufentanil increased the Tregs number, and the effect of sufentanil was more significant under the same analgesic effect with fentanyl. In the 38 operated cases, both the Tregs frequencies and Foxp3 mRNA expression on D1 decreased in comparison to those on D0, but then recovered on D7. By comparing SF and F group, there ware no significant differences in Tregs frequencies and Foxp3 mRNA expression on D0, D1 and D7. Conclusion: With the same analgesic potency, sufentanil is more powerful in increasing the Tregs quantity than fentanyl in vitro. But there are no significant differences as to Tregs frequencies between sufentanil anesthesia and fentanyl anesthesia perioperatively. Further studies are needed to determine the differences in the Tregs function and long-term outcome of these patients.     

Dendritic cells expand antigen-specific Foxp3+CD25+CD4+ regulatory T cells including suppressors of alloreactivity

Summary: Thymic derived naturally occurring CD25⁺CD4⁺ T regulatory cells (Tregs) suppress immune responses, including transplantation. Here we discuss the capacity of dendritic cells (DCs) to expand antigen‐specific Tregs, particularly polyclonal Tregs directed to alloantigens. Initial studies have shown that mature DCs are specialized antigen‐presenting cells (APCs) for expanding antigen‐specific CD25⁺ CD4⁺ Tregs from TCR transgenic mice. When triggered by specific antigen, these Tregs act back on immature DCs to block the upregulation of CD80 and CD86 costimulatory molecules. More recently, DCs have been used to expand alloantigen‐specific CD25⁺CD4⁺ Tregs from the polyclonal repertoire in the presence of interleukin‐2 (IL‐2). Allogeneic DCs are much more effective than allogeneic spleen cells for expanding CD25⁺CD4⁺ Tregs. The DC‐expanded Tregs continue to express high levels of Foxp3, even without supplemental IL‐2, whereas spleen cells poorly sustain Foxp3 expression. When suppressive activity is tested, relatively small numbers of DC‐expanded CD25⁺CD4⁺ Tregs exert antigen‐specific suppression in the mixed leukocyte reaction (MLR), blocking immune responses to the original stimulating strain 10 times more effectively than to third party stimulating cells. DC‐expanded Tregs also retard graft versus host disease (GVHD) across full major histocompatibility complex (MHC) barriers. In vitro and in vivo, the alloantigen‐specific CD25⁺CD4⁺ Tregs are much more effective suppressors of transplantation reactions than polyclonal populations. We suggest that the expansion of Tregs from a polyclonal repertoire via antigen‐presenting DCs will provide a means for antigen‐specific control of unwanted immune reactions.     

CD8+ lymphocyte phenotype and cytokine production in long-term non-progressor and in progressor patients with HIV-1 infection

In most HIV-1-infected patients, clinical and immunological progression develops within a few years. Few infected people, termed long-term non-progressors (LTNP), remain healthy and immunologically stable for a long time. The factors governing the maintenance of this condition are not well known, but it is conceivable that CD8⁺ lymphocytes, cells that play a central role in controlling in vitro HIV replication, may have a part in vivo in this process. The aim of this study was to characterize the phenotypic profile and the cytokine production of CD8⁺ cells in a group of LTNP patients who had stable CD4⁺ cell counts (>500/mm³) for at least 7 years. Their CD8⁺ absolute numbers were similar to a control group composed of HIV-1⁺ patients who have a progressive decline of their CD4⁺ cell counts. However, our multiparameter immunofluorescence studies show that a clinical and immunologically stable condition is associated with the presence of a CD28⁺, CD95 strongly positive CD8⁺ population, while disease progression is marked by the CD28⁻CD95⁺CD8⁺ subset. Purified CD8⁺ cells from LTNP retain their ability to produce IL-2, interferon-gamma (IFN-γ) and, to a lesser degree, to produce IL-10 and IL-4. In contrast, CD8⁺ cells from progressors are unable to secrete IL-2 and IL-10. Although CD8⁺ cytokine profile does not fit with the proposed T helper (Th)1/Th2 switch in progressive HIV infection, LTNP CD8⁺ T cells maintain their capacity to produce IL-2 and IL-10 (Th0-like), a pattern very similar to that observed in normal HIV healthy controls. We suggest that CD8⁺ cells expressing CD28, CD95 and having a Th0-like profile may be considered to be associated with long-term survival.     

Programmed cell death 2 functions as a tumor suppressor in osteosarcoma

Objectives: To investigate the role of programmed cell death 2 (PDCD2) in osteosarcoma (OS), along with correlations between PDCD2 and CD4⁺/CD8⁺. Methods: Sprague-Dawley (SD) rats were randomly assigned to control group and OS group. The OS group rats were subjected to induce models of OS by transplantation with UMR106 cells. Peripheral blood was collected to test the percentages of the CD4⁺ and CD8⁺ cell subsets using flow cytometry (FCM). Western blotting was performed to determine the PDCD2 protein level. The correlations between PDCD2 and CD4⁺/CD8⁺ were analyzed by Pearson correlation coefficient. Besides, specific small interfering RNAs (siRNA) against PDCD2 and nonspecific (NS)-siRNA were transfected into UMR106 cells. Cell viability and invasive ability were determined after transfection. Results: CD4⁺ cells percentages were significantly decreased in the OS group, while CD8⁺ cells were significantly increased (P < 0.05). The PDCD2 protein levels were markedly lower than that in the control group (P < 0.05). Additionally, PDCD2 was positively correlated with CD4⁺ (R² = 0.66, P < 0.05), but was negatively correlated with CD8⁺ (R² = -0.94, P < 0.05). Moreover, the cell viability and invasion ability were significantly higher than that in the control group and the NS siRNA group after transfection with PDCD2 siRNA (P < 0.05). Conclusion: These results suggest that PDCD2 is involved in the pathogenesis of OS, and PDCD2 may play an important role in tumor suppression. These mechanisms might be related to immune response induced by CD4⁺ and CD8⁺ T cells.     

Involvement of Foxp3-expressing CD4+ CD25+ regulatory T cells in the development of tolerance induced by transforming growth factor-beta2-treated antigen-presenting cells

A growing body of evidence has shown that professional antigen-presenting cells (APC) treated with transforming growth factor-β (TGF-β) can induce a systemic antigen (Ag)-specific tolerance, similar to anterior chamber-associated immune deviation (ACAID). However, the exact mechanism for immune tolerance induced by TGF-β-treated APC has not been elucidated. In this study, we showed that intravenous injection of ovalbumin (OVA)-pulsed APC treated with TGF-β₂ induced a peripheral tolerance as evidenced by an impaired delayed-type hypersensitivity (DTH) response. CD4⁺ T cells from mice receiving an intravenous injection of TGF-β₂-treated APC pulsed with OVA could adoptively transfer a specific tolerance to naïve mice. An increased frequency of FoxP3-expressing CD4⁺ CD25⁺ T cells was observed in mice with tolerance. CD4⁺CD25⁺ T cells from TGF-β₂-treated APC-injected mice produced a large amount of TGF-β₁ and exhibited an in vitro antigen-specific suppressive activity. CD4⁺ CD25⁺ T cells from TGF-β₂-treated APC-injected mice were able to inhibit the antigen-specific DTH response significantly when adoptively transferred to naïve mice. These results indicate that FoxP3-expressing CD4⁺ CD25⁺ T cells might be actively involved in the development of tolerance induced by TGF-β₂-treated APC.     

CD4+ CD25high Foxp3+ regulatory T cells downregulate human Vδ2+ T-lymphocyte function triggered by anti-CD3 or phosphoantigen

Vδ2⁺ T cells, the major circulating T-cell receptor-γδ-positive (TCR-γδ⁺) T-cell subset in healthy adults, are involved in immunity against many microbial pathogens including Mycobacterium tuberculosis. Vδ2⁺ T cells recognize small phosphorylated metabolites (phosphoantigens), expand in response to whole M. tuberculosis bacilli, and complement the protective functions of CD4⁺ T cells. CD4⁺ CD25^high Foxp3⁺ T cells (Tregs) comprise 5–10% of circulating T cells and are increased in patients with active tuberculosis (TB). We investigated whether, in addition to their known role in suppressing TCR-αβ⁺ lymphocytes, Tregs suppress Vδ2⁺ T-cell function. We found that depletion of Tregs from peripheral blood mononuclear cells increased Vδ2⁺ T-cell expansion in response to M. tuberculosis (H37Ra) in tuberculin-skin-test-positive donors. We developed a suppression assay with fluorescence-activated cell sorting-purified Tregs and Vδ2⁺ T cells by coincubating the two cell types at a 1 : 1 ratio. The Tregs partially suppressed interferon-γ secretion by Vδ2⁺ T cells in response to anti-CD3 monoclonal antibody plus interleukin-2 (IL-2). In addition, Tregs downregulated the Vδ2⁺ T-cell interferon-γ responses induced by phosphoantigen (BrHPP) and IL-2. Under the latter conditions there was no TCR stimulus for Tregs and therefore IL-2 probably triggered suppressor activity. Addition of purified protein derivative (PPD) increased the suppression of Vδ2⁺ T cells, suggesting that PPD activated antigen-specific Tregs. Our study provides evidence that Tregs suppress both anti-CD3 and antigen-driven Vδ2⁺ T-cell activation. Antigen-specific Tregs may therefore contribute to the Vδ2⁺ T-cell functional deficiencies observed in TB.     

Oridonin promotes CD4+/CD25+ Treg differentiation, modulates Th1/Th2 balance and induces HO-1 in rat splenic lymphocytes

Objective and design: Oridonin is an ent-kaurene diterpenoid extracted from Isodon Serra, and we have previously demonstrated its immunosuppressive effect. Our goal was to study how Oridonin impacts CD4⁺/CD25⁺ regulatory T cells (Tregs) and Th1/Th2 balance, as well as its effect on the anti-inflammatory target HO-1. Material: Splenic lymphocytes were prepared from male 6–8-week-old SD rats. Treatment: Cells were cultured in four groups as Oridonin-L (Oridonin 12.5 μmol/l), Oridonin-H (Oridonin 25 μmol/l), Cobalt protoporphyrin (Copp 50 μmol/l) and control (DMSO) with stimulation of ConA (5 μg/ml) for 48 h or with no stimulation for 12 h. Method: We set up a model of Th1 polarization in vitro using ConA stimulation; ratios of CD4⁺/CD25⁺ Tregs (confirmed by the expression of Foxp3) were measured by flow cytometry, and levels of IL-2, IFN-γ, TGF-β and IL-10 were measured by ELISA. In addition, HO-1 expression was measured without stimulation with ConA by RT-PCR and Western blotting, and HO-1 level in vitro was then measured by enzyme activity assay. p<0.05 (t-test) was taken as the level of statistical significance. Result: Oridonin promoted differentiation towards CD4⁺/CD25⁺ Tregs, inhibited IL-2 and IFN-γ but induced TGF-β and IL-10, thus rectifed the Th1 polarization. Moreover, Oridonin induced the expression of HO-1 mRNA and protein, and HO-1 activity in vitro was enhanced accordingly. Conclusion: The results suggest that Oridonin has a distinct effect on promoting CD4⁺/CD25⁺ Treg differentiation and modulating Th1/Th2 balance, and this effect may be achieved via inducing the anti-inflammatory target HO-1. Received 16 October 2007; accepted by G. Wallace 26 November 2007     

A profile of TNFR2+ regulatory T cells and CD103+ dendritic cells in the peripheral blood of patients with asthma

The interaction of tolerogenic CD103⁺ dendritic cells (DCs) with regulatory T (Tregs) cells modulates immune responses by inducing immune tolerance. Hence, we determined the proportion of these cells in the peripheral blood mononuclear cells (PBMC) of asthmatic patients. We observed lower trends of CD11b^-CD103⁺ DCs and CD86 within CD11b^-CD103⁺ DCs, while increased levels of Foxp3 expressing CD25^+/-TNFR2⁺ cells in asthmatics. There was a positive correlation in the expression of Foxp3 within CD3⁺CD4⁺CD25⁺TNFR2⁺ Tregs and CD11b^-CD103⁺ as well as the expression of CD86 within HLA-DR⁺CD11c⁺CD11b^-CD103⁺ DCs. In conclusion, we suggest that the increased levels of Tregs in blood could continuously suppress the T helper 2 (Th2) cells activation in the circulation which is also supported by the increase of anti-inflammatory cytokines IL-10 and TNF. Overall, functional immunoregulation of the regulatory cells, particularly Tregs, exhibit immune suppression and induce immune tolerance linked with the immune activation by the antigen presenting cells (APC).     

CD<Subscript>4</Subscript><Superscript>+</Superscript>CD<Subscript>25</Subscript><Superscript>+</Superscript> Regulatory T Cells Decreased the Antitumor Activity of Cytokine-Induced Killer (CIK) Cells of Lung Cancer Patients

CD₄ ⁺CD₂₅ ⁺ regulatory T cells (Tregs) have been shown to inhibit cytotoxic lymphocytes-mediated immune responses. Cytokine-induced killer (CIK) cells exert high impact on adoptive immunotherapeutic approaches. Therefore, the purpose of this report was to determine the effect of Tregs on CIK cell growth and CIK-induced cytotoxicity for inhibition of tumor growth in vivo as well as in vitro. After depletion of CD₄ ⁺CD₂₅ ⁺ cells before culture, the proliferation and cytotoxicity of CIK cells, which indicated in bromodeoxyuridine (BrdU) and lactic dehydrogenase (LDH) assays, were significantly increased. Depletion of CD₄ ⁺CD₂₅ ⁺ cells preculture also enhanced the suppression effect on the lung cancer cells inoculated in experimental animals. Blockage of glucocorticoid-induced tumor necrosis factor receptor (GITR) and transforming growth factor β1 (TGF-β1) by antibodies partially abrogated the suppressive effect of CD₄ ⁺CD₂₅ ⁺ cells on CIK. These results indicated that Tregs could inhibit the antitumor activity of CIK cells. The molecules TGF-β and GITR may contribute to the suppressive function of CD₄ ⁺CD₂₅ ⁺ cells.     

Attenuation of Peripheral Regulatory T-Cell Suppression of Skin-Homing CD8+T Cells in Atopic Dermatitis

Purpose

Cutaneous lymphocyte-associated antigen (CLA)-expressing CD8⁺T cells have been known to play an important role in the pathogenesis of atopic dermatitis (AD). However, the mechanisms underlying the loss of self-tolerance remain unclear. Regulatory T cells (Tregs) play a key role in the development of homeostasis in the immune system. We, therefore, hypothesized that a reduced ability of Tregs to inhibit autologous CD8⁺CLA⁺T cells might be underlying mechanism in AD.

Materials and Methods

CD8⁺CLA⁺T cells and Tregs were obtained from the peripheral blood of AD patients and control volunteers. The frequencies of CD8⁺CLA⁺T cells were evaluated. The proliferative responses of CD8⁺CLA⁺T cells were assessed by flow cytometry, and the levels of transforming growth factor-β1 (TGF-β1) and interleukin-10 (IL-10) in culture supernatants were detected by enzyme-linked immunosorbent assay.

Results

Our results revealed higher frequency and increased expression of perforin and granzyme-B in peripheral CD8⁺CLA⁺T cells in AD, and lower inhibitory ability of Tregs on proliferation of CD8⁺CLA⁺T cells in AD. Meanwhile, the levels of TGF-β1 produced by Tregs were significantly lower in AD, and anti-TGF-β1 abolished such suppression.

Conclusion

The attenuated inhibitory ability of Tregs on hyper-activated autologous CD8⁺CLA⁺T cells, mediated by TGF-β1, plays an important role in the pathogenesis of AD.     

Upregulation of CD4+CD25+ T lymphocyte by adenovirus-mediated gene transfer of CTLA4Ig fusion protein in experimental autoimmune myocarditis

Objective: To explore the effects of adenovirus vector-mediated gene transfer of CTLA4Ig fusion protein on CD4⁺CD25⁺ T cells in experimental autoimmune myocarditis (EAM).

Methods: EAM was induced by porcine cardiac myosin as previously described. Adenovirus vector-mediated CTLA4Ig gene was administrated intravenously in EAM rats on days 1, 4 and 7, with EGFP as control. On day 21, myocardium histopathology was examined and CD4⁺CD25⁺ T cells were isolated. Proliferation and suppression assays were used to evaluate the suppressive capacity of CD4⁺CD25⁺ T cells in vitro. Relative mRNA level of Foxp3 and TGF-β was determined by quantitative real-time RT-PCR; expression of CTLA-4, B7-1 and B7-2 protein was compared with Western blot in CD4⁺CD25⁺ T_regs.

Results: Severe inflammatory lesions were observed in the hearts of EGFP-treated EAM rats and the untreated ones, while Ad–CMV–CTLA4Ig alleviated the myocarditis histologically. Adenovirus vector-mediated CTLA4Ig gene transfer up-regulated the proportion of CD4⁺CD25⁺ T_regs significantly. T cell proliferation was greatly inhibited in the CTLA4Ig group compared with the untreated and EGFP-treated groups in vitro. CTLA-4 and B7-2 proteins were down-regulated in the CTLA4Ig group, Foxp3 and TGF-β mRNA was up-regulated significantly by CTLA4Ig treatment.

Conclusions: Adenovirus vector-mediated CTLA4Ig gene transfer alleviated inflammation in EAM, one of the potential mechanisms is up-regulation of CD4⁺CD25⁺ T_regs.     

Dual immunoregulatory pathways of 4-1BB signaling

It is perhaps rare to encounter among the various immunologically competent receptor–ligand pairs that a single cell surface determinant unleashes both a hidden suppressive function and costimulation. 4-1BB, an activation-induced tumor necrosis factor receptor family member chiefly viewed as a powerful T-cell costimulatory molecule, is one such example. Accumulated evidence in recent years uncovered an unknown facet of in vivo 4-1BB signaling (i.e., “active suppression”). Although in vitro signaling via 4-1BB is shown to support both CD4⁺ and CD8⁺ T-cell responses, the same induces a predominant CD8⁺ T-cell response suppressing CD4⁺ T-cell function when applied in vivo. How, when, and why such dual immunoregulatory effect of anti-4-1BB monoclonal antibody (MAB) comes into play is currently the focus of intense research. Existing data, although not complete, uncover several important aspects of in vivo 4-1BB signaling in the amelioration or exacerbation of various immune disorders. Despite minor disagreements, a majority agree that upregulation of interferon (IFN)-γ is critical to anti-4-1BB MAB therapy in addition to immune modulators such as interleukin 2, transforming growth factor β, and indolamine 2,3-dioxygenase⁵, all of which contribute greatly to the success of anti-4-1BB MAB-based immunotherapy. Anti-4-1BB MAB-mediated expansion of novel CD11c⁺CD8⁺ T cells is additional weaponry that appears critical for its in vivo suppressive function. These CD11c⁺CD8⁺ T cells express high levels of IFN-γ, become effective killers, and mediate selective suppression of CD4⁺ T cells. In this review, we discuss the dual nature (costimulatory and suppressive) of 4-1BB-mediated immune regulation, its current status, future direction, and its impact on the immune system, with special reference to its immunotherapy.     

Regulatory CD4+CD25+ T-cells are Controlled by Multiple Pathways at Multiple Levels

CD4⁺CD25⁺ regulatory T-cells (Treg cells) are an important subset of T-cells that functions to negatively control immune responses to self or non-self antigens. Depletion of CD4⁺CD25⁺ Treg cells leads to the occurrence of lymphoproliferative autoimmune diseases in animals and humans. Therefore, CD4⁺CD25⁺ Treg cells must be tightly regulated in the physiologic situation. In this article, we try to summarize the regulating pathways of the development, survival, and function of CD4⁺CD25⁺ Treg cells at multiple levels and multiple pathways, including the dendritic cells, costimulatory signals, cytokines, as well as intracellular signals.     

Deacetylase inhibition increases regulatory T cell function and decreases incidence and severity of collagen-induced arthritis

Collagen-induced arthritis (CIA) is an established mouse model of disease with hallmarks of clinical rheumatoid arthritis. Histone/protein deacetylase inhibitors (HDACi) are known to inhibit the pathogenesis of CIA and other models of autoimmune disease, although the mechanisms responsible are unclear. Regulatory T cell (Treg) function is defective in rheumatoid arthritis. FOXP3 proteins in Tregs are present in a dynamic protein complex containing histone acetyltransferase and HDAC enzymes, and FOXP3 itself is acetylated on lysine residues. We therefore investigated the effects of HDACi therapy on regulatory T cell function in the CIA model. Administration of an HDACi, valproic acid (VPA), significantly decreased disease incidence (p < 0.005) and severity (p < 0.03) in CIA. In addition, VPA treatment increased both the suppressive function of CD4⁺CD25⁺ Tregs (p < 0.04) and the numbers of CD25⁺FOXP3⁺ Tregs in vivo. Hence, clinically approved HDACi such as VPA may limit autoimmune disease in vivo through effects on the production and function of FOXP3⁺ Treg cells.     

Role of myeloid-derived suppressor cells in mouse pre-sensitized cardiac transplant model

Harness of sensitized transplantation remains a clinical challenge particularly in parallel with prolonged cold ischemia time (PCI)-mediated injury. Our present study was to test the role of myeloid-derived suppressor cells (MDSCs) in mouse pre-sensitized transplantation. Our findings revealed that CD11b + Gr1^low MDSC was shown to have strong suppressive activity. MDSCs subsets from the tolerated mice exhibited higher suppressive capacities compared with counterparts from naive (untreated) mice. Depletion of Tregs could not affect splenic CD11b + Gr1^-low MDSC frequency, but increase peripheral and intragraft CD11b + Gr1^-low frequency. Intriguingly, boost of Tregs remarkably caused an increase of CD11b + Gr1^-low frequency in the graft, peripheral blood, and spleen. Furthermore, peripheral CD11b + Gr1^-low cells were massively accumulated at the early stage when allogeneic immune response was enhanced. Taken together, MDSCs could prevent grafts from PCI-mediated injury independent on Tregs in the pre-sensitized transplant recipients. Utilization of MDSC subset particularly CD11b + Gr1^-low might provide a novel insight into improving graft outcome under such clinical scenarios.     

Down-regulation of TET2 in CD3+ and CD34+ cells of myelodysplastic syndromes and enhances CD34+ cells proliferation

Aims and background: To investigate the expressions of TET2 mRNA in bone marrow CD3⁺ and CD34⁺ cells of the patients with myelodysplastic syndromes (MDS) and to study the effect of silencing TET2 by small interfering RNA (siRNA) on the biological characteristics of CD34⁺ cells. Methods: CD3⁺ and CD34⁺ cells were sorted by magnetic activated cell-sorting system from bone marrow of MDS patients and controls. The mRNA expressions of TET2 in bone marrow CD3⁺ and CD34⁺ cells of 28 MDS patients and 20 controls were detected by qPCR. The silencing effect of RNA interference (RNAi) on TET2 expression in CD34⁺ bone marrow cells of normal control was identified by qPCR and Western blot analysis. The cell cycle kinetics and cell apoptosis were then detected by flow cytometry. Results: The expression of TET2 mRNA in CD3⁺ and CD34⁺ cells was down-regulated in MDS compared with that in controls [(0.16±0.11) vs. (1.05±0.32) (P<0.001); (0.58±0.26) vs. (1.25±0.94) (P<0.005)]. The siRNA targeting TET2 suppressed the expression of TET2 in normal CD34⁺ cells. Meanwhile, the proliferation activity was significantly enhanced [G0/G1: (87.82±8.25)% vs. (92.65±7.06)% and (93.60±5.54)%, P<0.05; S: (11.50±8.31)% vs. (6.92±7.04)% and (5.95±5.53)%, P<0.05] and the apoptosis rate was declined [(21.28±9.73)% vs. (26.17±9.88)% and (26.20±9.78)%] in the cells which transfected with TET2 siRNA as compared to those in the cells transfected with scrambled siRNA and control cells. Conclusions: The TET2 expression of in CD3⁺ and CD34⁺ cells of MDS patients was decreased. Suppression of TET2 expression renders the CD34⁺ cells harboring more aggressive phenotype. This preliminary finding suggests that CD34⁺ cells lowering expression of TET2 may play an oncogenic role on myeloid tumor and CD3⁺ T cells of MDS patients may be derived from the malignant clone.     

Linfocitos NKT invariantes: ontogenia,fenotipo y función

Invariant natural killer (iNK) T lymphocytes (iNKTL) were initially identified due to having similar characteristics to NK and T cells. Nowadays, it is known that these cells are T lymphocytes with unique characteristics, from their maturing process and differentiation in the thymus to the response at specific stimuli. Studies in mice have been useful for examining the maturing process and differentiation pathways of iNKTL. In these pathways the CD1d molecule has a fundamental role in the selection of their precursors, and also in the peripheral glycolipid presentation for the activation of iNKTL. Four sub-populations of iNKTL CD4⁺, CD8αβ⁺, CD8αα⁺ and Double Negatives, were identified in human peripheral blood. They particularly cooperate and interact with others immune cells. The information obtained by studying iNKTL opens the possibility of proposing this cell line as a therapeutic alternative, but further studies on the behavior of this type of lymphocyte are needed.