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Suppressive Activity (suppressive + activity)

Distribution by Scientific Domains

Medical Sciences	85%
Life Sciences	7%

Distribution within Medical Sciences

Immunology	47%
Allergy & Clinical Immunology	12%

Selected Abstracts

Regulatory effects of senescence marker protein 30 on the proliferation of hepatocytes

PATHOLOGY INTERNATIONAL, Issue 7 2001
Terunobu Ishigami
Senescence marker protein 30 (SMP 30) is preferentially expressed in the liver. One of its remarkable functions is the protection of cells against various injuries by enhancement of membrane calcium-pump activity. We analyzed the role of SMP 30 in hepatocyte proliferation. SMP 30 expression was decreased initially, then increased along with hepatic regeneration, after carbon tetrachloride (CCl4) administration. SMP 30 expression was decreased in the necrotic phase and then gradually increased. Its increase was slightly delayed just after the mitotic phase. These results lead us to speculate that mitoses of hepatic cells induce enhanced SMP 30 expression. In contrast, administration of lead nitrate (LN) as a hepatic mitogen induced a more stable increase of SMP 30 expression. To estimate the effect of SMP 30 on cell proliferation, we evaluated hepatic mitosis in wild-type and SMP 30-deficient knockout (KO) mice after CCl4 administration. We found an increase in mitotic numbers in hepatocytes of KO mice. This result suggests that SMP 30 has a suppressive effect on cell proliferation. Suppressive activity of SMP 30 cDNA was shown in cultured hepatoblastic cells. Our results suggest that SMP 30 performs a regulatory function in liver regeneration. [source]

Suppressive activity of fexofenadine hydrochloride on metalloproteinase production from nasal fibroblasts in vitro

CLINICAL & EXPERIMENTAL ALLERGY, Issue 12 2004
K. Asano
Summary Background Allergic rhinitis (AR) is an inflammatory disease characterized by nasal wall remodelling with intense infiltration of eosinophils and mast cells/basophils. Matrix metalloproteinases (MMPs), MMP-2 and MMP-9, are the major proteolytic enzymes that induce airway remodelling. These enzymes are also important in the migration of inflammatory cells through basement membrane components. Objective We evaluated whether fexofenadine hydrochloride (FEX), the carboxylic acid metabolite of terfenadine with selective H1 -receptor antagonist activity, could inhibit MMP production from nasal fibroblasts (NFs) in response to TNF-, stimulation in vitro. Methods NFs were established from nasal polyp-derived fibroblasts (PFs) taken from patients with AR. Nasal mucosal fibroblasts (MFs) were also induced from nasal mucosal tissues from septal deformity patients without allergy. PF and MF (2 × 105 cells/mL, each) were stimulated with TNF-, in the presence of various concentrations of FEX. After 24 h, culture supernatants were obtained and assayed for MMP-2, MMP-9, tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 levels by ELISA. The influence of FEX on mRNA expression of MMPs and TIMPs in 4 h-cultured cells was also evaluated by real-time RT-PCR. Furthermore, nuclear factor-,B (NF-,B) activation in fibroblasts treated with FEX for 4 h was examined by ELISA. Results FEX at more than 350 ng/mL inhibited the production of MMP-2 and MMP-9 from both PF and MF in response to TNF-, stimulation, whereas TIMP-1 and TIMP-2 production was scarcely affected by FEX. FEX also inhibited MMP mRNA expression and NF-,B activation in PF and MF after TNF-, stimulation. Conclusion The present data suggest that the attenuating effect of FEX on MMP-2 and -9 production from NFs induced by inflammatory stimulation may underlie the therapeutic mode of action of the agent on allergic diseases, including AR. [source]

The Jak Inhibitor CP-690,550 Preserves the Function of CD4+CD25brightFoxP3+ Regulatory T Cells and Inhibits Effector T Cells

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 8 2010
V. D. K. D. Sewgobind
The Jak inhibitor CP-690,550 inhibits alloreactivity and is currently being investigated for prevention of allograft rejection after transplantation. In this study, we examined the effect of CP-690,550 on IL-2-mediated Jak/STAT5 phosphorylation by CD4+CD25brightFoxP3+CD127,/low T cells (Treg) and CD4+CD25neg effector T cells (Teff) in kidney transplant (KTx) patients. Phosphospecific flow cytometry was used to study the effect of CP-690,550 on IL-2-induced intracellular STAT5-phosphorylation. IL-2-induced phosphorylation of STAT5 (P-STAT5) in both Treg and Teff, which was significantly higher for CD4+CD25bright Treg (increased by 71%, mean) than for CD4+CD25neg Teff (increased by 42%). In the presence of 100 ng/mL CP-690,550, a clinically relevant exposure, IL-2-induced P-STAT5 was partially inhibited in CD4+CD25brightTreg (% inhibition; 51%), while almost completely blocked in Teff (%inhibition; 84%, p = 0.03). The IC50 was 2,3 times higher for Treg (104 ng/mL) than for Teff (40 ng/mL, p = 0.02). In the presence of CP-690,550, Treg exhibited additional suppressive activities on the alloactivated proliferation of Teff (56%, mean). In addition, CD4+CD25bright Treg from KTx-patients receiving CP-690,550 vigorously suppressed the proliferation of Teff (87%, mean). Our findings show that CP-690,550 effectively inhibits Teff function but preserves the suppressive activity of CD4+CD25bright regulatory T cells. [source]

Tumor expression of CD200 inhibits IL-10 production by tumor-associated myeloid cells and prevents tumor immune evasion of CTL therapy

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 9 2010
Lixin Wang
Abstract CD200 is a cell-surface glycoprotein that functions through interaction with the CD200 receptor on myeloid lineage cells to regulate myeloid cell functions. Expression of CD200 has been implicated in multiple types of human cancer; however, the impact of tumor expression of CD200 on tumor immunity remains poorly understood. To evaluate this issue, we generated CD200-positive mouse plasmacytoma J558 and mastocytoma P815 cells. We found that established CD200-positive tumors were often completely rejected by adoptively transferred CTL without tumor recurrence; in contrast, CD200-negative tumors were initially rejected by adoptively transferred CTL but the majority of tumors recurred. Tumor expression of CD200 significantly inhibited suppressive activity and IL-10 production by tumor-associated myeloid cells (TAMC), and as a result, more CTL accumulated in the tumor and exhibited a greater capacity to produce IFN-, in CD200-positive tumors than in CD200-negative tumors. Neutralization of IL-10 significantly inhibited the suppressor activity of TAMC, and IL-10-deficiency allowed TAMC to kill cancer cells and their antigenic variants, which prevented tumor recurrence during CTL therapy. Thus, tumor expression of CD200 prevents tumor recurrence via inhibiting IL-10 production by TAMC. [source]

Regulatory T cells in human geohelminth infection suppress immune responses to BCG and Plasmodium falciparum

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 2 2010
Linda J. Wammes
Abstract Chronic helminth infections induce T-cell hyporesponsiveness, which may affect immune responses to other pathogens or to vaccines. This study investigates the influence of Treg activity on proliferation and cytokine responses to BCG and Plasmodium falciparum -parasitized RBC in Indonesian schoolchildren. Geohelminth-infected children's in vitro T-cell proliferation to either BCG or pRBC was reduced compared to that of uninfected children. Although the frequency of CD4+CD25hiFOXP3+ T cells was similar regardless of infection status, the suppressive activity differed between geohelminth-infected and geohelminth-uninfected groups: Ag-specific proliferative responses increased upon CD4+CD25hi T-cell depletion in geohelminth-infected subjects only. In addition, IFN-, production in response to both BCG and parasitized RBC was increased after removal of CD4+CD25hi T cells. These data demonstrate that geohelminth-associated Treg influence immune responses to bystander Ag of mycobacteria and plasmodia. Geohelminth-induced immune modulation may have important consequences for co-endemic infections and vaccine trials. [source]

IL-2 induces in vivo suppression by CD4+CD25+Foxp3+ regulatory T cells

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 6 2008
Susan Brandenburg
Abstract Interleukin-2 (IL-2) treatment is currently used to enhance T cell-mediated immune responses against tumors or in viral infections. At the same time, IL-2 is essential for the peripheral homeostasis of CD4+CD25+Foxp3+ regulatory T cells (Treg). In our study, we show that IL-2 is also an important activator of Treg suppressive activity in vivo. IL-2 treatment induces Treg expansion as well as IL-10 production and increases their suppressive potential in vitro. Importantly, in vivo application of IL-2 via gene-gun vaccination using IL-2 encoding DNA plasmids (pIL-2) inhibited naive antigen-specific T cell proliferation as well as a Th1-induced delayed type hypersensitivity response. The suppressive effect can be transferred onto naive animals by Treg from IL-2-treated mice and the suppression depends on the synergistic action of IL-10 and TGF-,. These data highlight that during therapeutic treatment with IL-2 the concomitant activation of Treg may indeed counteract the intended activation of cellular immunity. [source]

Kinetics of CD8+ effector T cell responses and induced CD4+ regulatory T cell responses during Friend retrovirus infection

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 10 2006
Gennadiy Zelinskyy
Abstract Cytolytic CD8+ T cells are critical for the control of acute Friend virus (FV) infection yet they fail to completely eliminate the virus during chronic infection because they are functionally impaired by regulatory T cells (Treg). We performed a kinetic analysis of T cell responses during FV infection to determine when dysfunction of CD8+ T cells and suppressive activity of CD4+ regulatory T cells develops. At 1,week post infection, virus-specific CD8+ T cells with effector phenotype and cytolytic potential expanded. Peak expansion was found at 12,days post infection, correlating with peak viral loads. After 2,weeks when viral loads dropped, numbers of activated CD8+ T cells started to decline. However, a population of virus-specific CD8+ T cells with effector phenotype was still detectable subsequently, but these cells had lost their ability to produce granzymes and to degranulate cytotoxic molecules. Contemporaneous with the development of CD8+ T cell dysfunction, different CD4+ T cell populations expressing cell surface markers for Treg and the Treg-associated transcription factor Foxp3 expanded. Transfer as well as depletion experiments indicated that regulatory CD4+ cells developed during the second week of FV infection and subsequently suppressed CD8+ T cell functions, which was associated with impaired virus clearance. [source]

Suppressive properties of human CD4+CD25+ regulatory T,cells are dependent on CTLA-4 expression

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 12 2004
Brigitte Birebent
Abstract It has been demonstrated that T,cells with regulatory properties are present within the peripheral blood CD4+CD25+ T,cell compartment. Here, we describe an original method to purify human CD4+CD25+CD152+ T,lymphocytes as living cells by forcing the exportation of CTLA-4 molecules stored in intracellular vesicules at the cell surface. By doing so, we demonstrate that CD4+CD25+ T,cells contain a smaller and more homogeneous population enriched in cells with in vitro regulatory activity. Moreover, we show that this enrichment in regulatory T,cells is associated with an increased expression of Foxp3 and that CD4+CD25+CD152+ T,lymphocytes display a much stronger suppressive activity in controlling in vitro proliferation of alloantigen-specific T,cells than CD4+CD25+CD152, T,lymphocytes purified in parallel. Lastly, by purifying such cells expressing CTLA-4, we demonstrate that indeed CTLA-4 is involved in CD4+CD25+CD152+ T,cell regulatory activity, while suppressive cytokines are not. [source]

Aging-dependent generation of suppressive CD4+CD25,R123loCD103+ T,cells in mice

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 9 2003
Jun Shimizu
Abstract Advancing age is associated with significant alterations in immune functions, including a decline in CD4 T,cell function, in both mice and humans. In our previous report, we showed that CD4+CD25, T,cells in aged (24-month-old) mice, especially after in vitro pre-stimulation of these cells, exhibit hyporesponsive and suppressive properties. We examined here whether the suppressive activity of aged CD4+CD25, T,cells is ascribable to a particular population within these cells. In vitro analyses revealed that cell populations rapidly extruding Rhodamine-123 (R123) (referred to as R123lo cells) in aged CD4+CD25, T,cells have a more potent suppressive function compared with R123hi populations. In addition, CD103+ cells in freshly prepared aged CD4+CD25,R123lo T,cells had a most potent suppressive activity. Both R123hi and R123lo populations had individually stronger suppressive activity after pre-stimulation than before pre-stimulation. Furthermore, the R123lo population in young CD4+CD25, T,cells also had different properties from R123hi T cells: low responsiveness, no additive effect in proliferation assays, and the gain of a suppressive function after in vitro pre-stimulation. Takentogether, these results suggest that CD4+CD25,R123lo T,cells are a unique population within whole CD4+CD25, T,cells. This population exists in the earlystage of the life span, and the properties in this population become obvious with aging, that is the gain of their suppressive activity. [source]

Functional analysis of the basic helix-loop-helix transcription factor DEC1 in circadian regulation

FEBS JOURNAL, Issue 22 2004
Interaction with BMAL
The basic helix-loop-helix transcription factor DEC1 is expressed in a circadian manner in the suprachiasmatic nucleus where it seems to play a role in regulating the mammalian circadian rhythm by suppressing the CLOCK/BMAL1-activated promoter. The interaction of DEC1 with BMAL1 has been suggested as one of the molecular mechanisms of the suppression [Honma, S., Kawamoto, T., Takagi, Y., Fujimoto, K., Sato, F., Noshiro, M., Kato, Y. & Honma, K. (2002) Nature419, 841,844]. Deletion analysis of DEC1 demonstrated that its N-terminal region, which includes the basic helix-loop-helix domain, was essential for both the suppressive activity and the interaction with BMAL1, as DEC1 lacking the basic region did not show any suppression or interaction. Furthermore, we found that Arg65 in the basic region, which is conserved among group B basic helix-loop-helix proteins, was responsible for the suppression, for the interaction with BMAL1 and for its binding to CACGTG E-boxes. However, substitution of His57 for Ala significantly reduced the E-box binding activity of DEC1, although it did not affect the interaction with BMAL1 or suppression of CLOCK/BMAL1-induced transcription. On the other hand, the basic region-deleted DEC1 acted in a dominant-negative manner for DEC1 activity, indicating that the basic region was not required for homodimer formation of DEC1. Moreover, mutant DEC1 also counteracted DEC2-mediated suppressive activity in a dominant-negative manner. The heterodimer formation of DEC1 and DEC2 was confirmed by pull-down assay. These findings suggest that the basic region of DEC1 participates in the transcriptional regulation through a protein,protein interaction with BMAL1 and DNA binding to the E-box. [source]

GANP suppresses DNA recombination, measured by direct-repeat ,-galactosidase gene construct, but does not suppress the type of recombination applying to immunoglobulin genes in mammalian cells

GENES TO CELLS, Issue 10 2007
Mikoto Yoshida
Immunoglobulin V-region somatic hypermutation and C-region class-switch recombination are initiated by activation-induced cytidine deaminase (AID) in B-cells. AID-induced DNA damage at the immunoglobulin S-region is known to be repaired by non-homologous end-joining, but repair mechanisms at the V-region remain to be elucidated. In Saccharomyces cerevisiae, DNA homologous recombination is regulated by the expression of Sac3, involved in actin assembly, cell cycle transition and mRNA metabolism. Here, we demonstrate that the Sac3-homologue GANP suppresses DNA recombination in a direct-repeat ,-galactosidase gene construct in mammalian cells. Homozygous ganp gene knockout is embryonic lethal in mice. Embryonic fibroblasts immortalized from hetero-deficient ganp+/, mice showed more DNA recombination than wild-type. In contrast, over-expression of GANP suppressed either spontaneous DNA recombination or that caused by the introduction of aid cDNA into NIH3T3 cells (susceptible to I-sceI restriction enzyme cleavage but not to RAG-mediated immunoglobulin gene recombination). GANP suppresses the DNA recombination not only on the extrachromosomal DNA construct but also on the integrated DNA. The Sac3-homology portion is necessary for the suppressive activity, but the truncated carboxyl terminal MCM3-binding/acetylating region adversely augmented DNA recombination, acting as a dominant negative form. Expression of full-length GANP is critical for suppression of DNA hyper-recombination in mammalian cells. [source]

Distinct regulatory roles of transforming growth factor-, and interleukin-4 in the development and maintenance of natural and induced CD4+ CD25+ Foxp3+ regulatory T cells

IMMUNOLOGY, Issue 1pt2 2009
Jana Prochazkova
Summary The development and function of CD4+ CD25+ Foxp3+ regulatory T cells (Tregs) are strictly regulated by cytokines. Here we show that transforming growth factor-, (TGF-,) and interleukin-4 (IL-4) play a crucial and antagonistic role in the development of Tregs. Additionally, these cytokines also have distinct effects on the maintenance of natural (nTregs) and antigen-induced (iTregs) Tregs. Using double-staining and tracking of proliferation of purified and carboxyflourescein succinimidyl ester (CFSE)-labelled mouse T-cell subpopulations we demonstrated that CD4+ CD25+ Foxp3+ iTregs develop upon alloantigenic stimulation in the presence of TGF-, exclusively from CD4+ CD25, Foxp3, precursors. Both the induction of Foxp3 expression and Treg proliferation were prevented when the cells were stimulated in the presence of IL-4. By contrast, nTregs did not proliferate in the presence of the antigen and TGF-,, and partially lost their Foxp3 expression. IL-4 not only prevented the development of iTregs, but also down-regulated the level of Foxp3 mRNA and decreased the number of Foxp3+ cells in a population of iTregs. Further analyses proved that IL-4 decreased the expression of Foxp3 only in a population of iTregs, whereas it substantially supported the survival of nTregs. Functional experiments showed that Tregs induced in the presence of alloantigen and TGF-, inhibited, on a per-cell basis, cell proliferation comparably to nTregs, and their suppressive capacity was not modulated by IL-4. These data suggest that TGF-, and IL-4 differentially regulate the development of Tregs and distinctly sustain Foxp3 expression and the number of nTregs and iTregs, but have no influence on the suppressive activity of Tregs on a per-cell basis. [source]

Apoptotic cells induce dendritic cell-mediated suppression via interferon-,-induced IDO

IMMUNOLOGY, Issue 1 2008
Charlotte A. Williams
Summary Dendritic cells (DC) are sensitive to their local environment and are affected by proximal cell death. This study investigated the modulatory effect of cell death on DC function. Monocyte-derived DC exposed to apoptotic Jurkat or primary T cells failed to induce phenotypic maturation of the DC and were unable to support CD4+ allogeneic T-cell proliferation compared with DC exposed to lipopolysaccharide (LPS) or necrotic cells. Apoptotic cells coincubated with LPS- or necrotic cell-induced mature DC significantly suppressed CD80, CD86 and CD83 and attenuated LPS-induced CD4+ T-cell proliferation. Reduced levels of interleukin-12 (IL-12), IL-10, IL-6, tumour necrosis factor-, and interferon-, (IFN-,) were found to be concomitant with the suppressive activity of apoptotic cells upon DC. Furthermore, intracellular staining confirmed IFN-, expression by DC in association with apoptotic environments. The specific generation of IFN-, by DC within apoptotic environments is suggestive of an anti-inflammatory role by the induction of indoleamine 2,3-dioxygenase (IDO). Both neutralization of IFN-, and IDO blockade demonstrated a role for IFN-, and IDO in the suppression of CD4+ T cells. Moreover, we demonstrate that IDO expression within the DC was found to be IFN-,-dependent. Blocking transforming growth factor-, (TGF-,) also produced a partial release in T-cell proliferation. Our study strongly suggests that apoptosis-induced DC suppression is not an immunological null event and two prime mediators underpinning these functional effects are IFN-,-induced IDO and TGF-,. [source]

Characterization of T-regulatory cells, induced by immature dendritic cells, which inhibit enteroantigen-reactive colitis-inducing T-cell responses in vitro and in vivo

IMMUNOLOGY, Issue 4 2004
Monika Gad
Summary Regulatory T (Treg) cells, derived from co-cultures of unfractionated CD4+ T cells and immature dendritic cells (DC), suppress enteroantigen-induced proliferation of CD4+ CD25, T cells. The DC-induced Treg cells are a mixture of CD25+ (10,20%) and CD25, (80,90%) T cells. However, all the suppressor activity in vitro and in vivo resides in the CD25+ T-cell subset. The CD25+ DC-induced Treg cells can inhibit enteroantigen-induced proliferation in vitro through a transwell membrane, and their function does not appear to depend on previous activation. DC-induced CD25+ Treg cells display a naïve phenotype, expressing high levels of CD45RB and l -selectin (CD62L). In addition, the DC-induced Treg cells mediate a stronger suppressive activity than prototype CD25+ regulatory T cells. The DC-induced Treg cells, and hereof purified CD25+ and CD25, T-cell fractions, were co-injected into severe combined immunodeficiency (SCID) mice with colitis-inducing CD4+ CD25, T cells. Both unfractionated CD4+ and purified CD25+ Treg cells fully protected the recipients against the development of colitis. In contrast, co-transfer of fractionated CD25, T cells offered no protection against disease development. Enterobacterial antigen-exposed CD4+ T cells of the protected mice secreted higher levels of interleukin-10 and lower levels of interferon-, than the unprotected mice. The present data demonstrate DC-induced CD4+ CD25+ Treg cells, which phenotypically and functionally differ from the generally accepted prototype of CD25+ Treg cells. These data may initiate new procedures for the expansion of Treg cells for clinical use. [source]

Down-modulation of programmed death 1 alters regulatory T cells and promotes experimental autoimmune encephalomyelitis

JOURNAL OF NEUROSCIENCE RESEARCH, Issue 1 2010
Chunhe Wang
Abstract The regulatory role of programmed death 1 (PD-1) was investigated in the development of experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. Typical EAE could be induced by immunization without pertussis toxin (PTX) in PD-1-null but not in wild-type (WT) mice. However, both strains developed a similar EAE phenotype when immunized with PTX or by adoptive transfer of pathogenic T cells. In WT mice that did not develop EAE after immunization without PTX, the frequency of CD4+FoxP3+ Treg cells was boosted in the periphery but not in the thymus. This increase in Treg frequency was abrogated by PD-1 deficiency or inclusion of PTX. In addition, PD-1 expression was critical to in vitro conversion of naïve myelin-specific CD4 T cells into Treg cells and was directly related to Treg suppressive activity. Finally, PD-1 was markedly down-modulated in the periphery of WT mice after administration of PTX. Therefore, down-modulation of PD-1 in Treg cells may abrogate Treg-mediated immune suppression, permitting the activation of myelin-reactive T cells and induction of EAE. © 2009 Wiley-Liss, Inc. [source]

Effector and regulatory mechanisms in allergic contact dermatitis

ALLERGY, Issue 12 2009
M. Vocanson
Allergic contact dermatitis (ACD), one of the commonest occupational diseases, is a T-cell-mediated skin inflammation caused by repeated skin exposure to contact allergens, i.e. nonprotein chemicals called haptens. Allergic contact dermatitis, also referred to as contact hypersensitivity, is mediated by CD8+ T cells, which are primed in lymphoid organs during the sensitization phase and are recruited in the skin upon re-exposure to the hapten. Subsets of CD4+ T cells endowed with suppressive activity are responsible for both the down-regulation of eczema in allergic patients and the prevention of priming to haptens in nonallergic individuals. Therefore, ACD should be considered as a breakdown of the skin immune tolerance to haptens. Recent advances in the pathophysiology of ACD have demonstrated the important role of skin innate immunity in the sensitization process and have revisited the dogma that Langerhans cells are mandatory for CD8+ T-cell priming. They have also introduced mast cells as a pivotal actor in the magnitude of the inflammatory reaction. Finally, the most recent studies address the nature, the mode and the site of action of the regulatory T cells that control the skin inflammation with the aim of developing new strategies of tolerance induction in allergic patients. [source]

The functional insufficiency of human CD4+CD25high T-regulatory cells in allergic asthma is subjected to TNF-, modulation

ALLERGY, Issue 1 2008
Y.-L. Lin
Background:, Natural CD4+CD25highFoxp3+ regulatory T (nTreg) cells are important in maintaining immunologic tolerance, but their role in the pathogenesis of allergic asthma is unclear. We studied the function of nTreg cells in allergic asthmatic children and assessed the factors which may relate to the functional insufficiency of nTreg cells. Methods:, The percentage of CD4+CD25high Treg cells, the expression of Foxp3, and the cell-induced suppressive activity of nTreg cells isolated from nonatopic controls, allergic asthmatics, and allergen-specific immunotherapy (AIT)-treated asthmatic patients were studied. Results:, Although the percentage of nTreg in peripheral blood mononuclear cells was increased, the expression of Foxp3 and its cell-induced suppressive activity were significantly lower in Dermatophagoides pteronyssinus (Der p)-sensitive asthmatic children when compared to nonatopic controls. In contrast, the expression of Foxp3 and the functional activity of nTreg cells were reversed in allergic asthmatics who received AIT. The addition of recombinant tumor necrosis factor (TNF)-, directly downregulated Foxp3 expression and abrogated the cell-induced suppressive function of Treg cells. The anti-TNF-, reagent, etanercept, restored the functional activity and Foxp3 expression of CD4+CD25high Treg derived from allergic asthmatics. Conclusions:, The functional insufficiency of nTreg cells in patients with allergic asthma may be related to the enhanced production of TNF-, and its effect on the Foxp3 expression. These results may explain, in part, the effectiveness of anti-TNF-, therapy in the treatment of allergic asthma. [source]

The Jak Inhibitor CP-690,550 Preserves the Function of CD4+CD25brightFoxP3+ Regulatory T Cells and Inhibits Effector T Cells

Isolated CD39 Expression on CD4+ T Cells Denotes both Regulatory and Memory Populations

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 10 2009
Q. Zhou
Foxp3+ regulatory T cells (Tregs) express both ectoenzymes CD39 and CD73, which in tandem hydrolyze pericellular ATP into adenosine, an immunoinhibitory molecule that contributes to Treg suppressive function. Using Foxp3GFP knockin mice, we noted that the mouse CD4+CD39+ T-cell pool contains two roughly equal size Foxp3+ and Foxp3, populations. While Foxp3+CD39+ cells are CD73bright and are the bone fide Tregs, Foxp3,CD39+ cells do not have suppressive activity and are CD44+CD62L,CD25,CD73dim/,, exhibiting memory cell phenotype. Functionally, CD39 expression on memory and Treg cells confers protection against ATP-induced apoptosis. Compared with Foxp3,CD39, naïve T cells, Foxp3,CD39+ cells freshly isolated from non-immunized mice express at rest significantly higher levels of mRNA for T-helper lineage-specific cytokines IFN-, (Th1), IL-4/IL-10 (Th2), IL-17A/F (Th17), as well as pro-inflammatory cytokines, and rapidly secrete these cytokines upon stimulation. Moreover, the presence of Foxp3,CD39+ cells inhibits TGF-, induction of Foxp3 in Foxp3,CD39, cells. Furthermore, when transferred in vivo, Foxp3,CD39+ cells rejected MHC-mismatched skin allografts in a much faster tempo than Foxp3,CD39, cells. Thus, besides Tregs, CD39 is also expressed on pre-existing memory T cells of Th1-, Th2- and Th17-types with heightened alloreactivity. [source]

Tolerization with Hsp65 induces protection against adjuvant-induced arthritis by modulating the antigen-directed interferon-,, interleukin-17, and antibody responses

ARTHRITIS & RHEUMATISM, Issue 1 2009
Shailesh R. Satpute
Objective Pretreatment of Lewis rats with soluble mycobacterial Hsp65 affords protection against subsequent adjuvant-induced arthritis (AIA). This study was aimed at unraveling the mechanisms underlying mycobacterial Hsp65,induced protection against arthritis, using contemporary parameters of immunity. Methods Lewis rats were given 3 intraperitoneal injections of mycobacterial Hsp65 in solution prior to the initiation of AIA with heat-killed Mycobacterium tuberculosis. Thereafter, mycobacterial Hsp65,specific T cell proliferative, cytokine, and antibody responses were tested in tolerized rats. The roles of anergy and the indoleamine 2,3 dioxygenase (IDO),tryptophan pathway in tolerance induction were assessed, and the frequency and suppressive function of CD4+FoxP3+ Treg cells were monitored. Also tested was the effect of mycobacterial Hsp65 tolerization on T cell responses to AIA-related mycobacterial Hsp70, mycobacterial Hsp10, and rat Hsp65. Results The AIA-protective effect of mycobacterial Hsp65,induced tolerance was associated with a significantly reduced T cell proliferative response to mycobacterial Hsp65, which was reversed by interleukin-2 (IL-2), indicating anergy induction. The production of interferon-, (but not IL-4/IL-10) was increased, with concurrent down-regulation of IL-17 expression by mycobacterial Hsp65,primed T cells. Neither the frequency nor the suppressive activity of CD4+FoxP3+ T cells changed following tolerization, but the serum level of anti,mycobacterial Hsp65 antibodies was increased. However, no evidence was observed for a role of IDO or cross-tolerance to mycobacterial Hsp70, mycobacterial Hsp10, or rat Hsp65. Conclusion Tolerization with soluble mycobacterial Hsp65 leads to suppression of IL-17, anergy induction, and enhanced production of anti,mycobacterial Hsp65 antibodies, which play a role in protection against AIA. These results are relevant to the development of effective immunotherapeutic approaches for autoimmune arthritis. [source]

Increased number and function of FoxP3 regulatory T cells during experimental arthritis

ARTHRITIS & RHEUMATISM, Issue 12 2008
Kristen Monte
Objective CD4+CD25+FoxP3+ regulatory T (Treg) cells are critical regulators of autoimmunity. Yet the number of Treg cells is paradoxically increased in rheumatoid arthritis (RA) patients, and Treg cells show variable activity in human studies. The objective of this study was to characterize the expansion and function of Treg cells during the initiation and progression of experimental arthritis. Methods To unequivocally identify Treg cells, we crossed FoxP3gfp mice with K/BxN mice to generate arthritic mice in which Treg cells express green fluorescence protein. We examined the expansion and function of Treg cells and effector T (Teff) cells during different stages of arthritis, using flow cytometry and cell proliferation analyses. Results In K/BxN mice, thymic selection of KRN T cells resulted in an enrichment of forkhead box P3 (FoxP3),positive Treg cells. Treg cell numbers increased during arthritis, with significant increases in spleens and draining lymph nodes, indicating selective tropism to sites of disease. In contrast to the in vitro unresponsiveness of Treg cells when cultured alone, substantial proportions of Treg cells proliferated in both nonarthritic and arthritic mice. However, they also underwent greater apoptosis, thereby maintaining equilibrium with Teff cells. Similarly, enhanced Treg cell,suppressive activity during arthritis was offset by greater resistance by their Teff cell counterparts and antigen-presenting cells. Conclusion In this well-established model of RA, the interplay of Teff cells and Treg cells in K/BxN mice recapitulated many features of the human disease. We demonstrated an ordered expansion of Treg cells during arthritis and dynamic changes in Treg cell and Teff cell functions. By elucidating factors that govern Treg cell and Teff cell development in K/BxNgfp mice, we will gain insight into the pathophysiology of and develop novel therapeutics for human RA. [source]

Reduced CD4+,CD25, T cell sensitivity to the suppressive function of CD4+,CD25high,CD127,/low regulatory T cells in patients with active systemic lupus erythematosus

ARTHRITIS & RHEUMATISM, Issue 7 2008
Ram Kumar Chowdary Venigalla
Objective CD4+,CD25high regulatory T (Treg) cells play a crucial role in the maintenance of self tolerance and prevention of organ-specific autoimmunity. The presence of many in vivo,preactivated CD4+,CD25++ T cells in patients with systemic lupus erythematosus (SLE) poses a difficulty in discriminating CD25++ activated T cells from CD25high Treg cells. To overcome this problem, we analyzed the phenotype and function of CD4+,CD25high,CD127,/low natural Treg (nTreg) cells isolated from the peripheral blood of patients with SLE. Methods CD4+,CD25high,CD127,/low nTreg cells and CD4+,CD25, responder T (Tresp) cells from patients with SLE and normal donors were separated by fluorescence-activated cell sorting. Cell proliferation was quantified by 3H-thymidine incorporation, and immunophenotyping of the cells was done using FACScan. Results Comparable percentages of CD4+,CD25high,FoxP3+ T cells were observed in patients with SLE and normal donors. Proliferation of SLE nTreg cells sorted into the subset CD4+,CD25high,CD127,/low was significantly decreased compared with that of SLE nTreg cells sorted into the subset CD4+,CD25high (mean ± SEM 2,223 ± 351 counts per minute versus 9,104 ± 1,720 cpm, respectively), while in normal donors, these values were 802 ± 177 cpm and 2,028 ± 548 cpm, respectively, confirming that effector cell contamination was reduced. Notably, the suppressive activity of nTreg cells was intact in all groups. However, CD4+,CD25, Tresp cells isolated from patients with active SLE were significantly less sensitive than those from patients with inactive SLE to the suppressive function of autologous or normal donor CD4+,CD25high,CD127,/low nTreg cells. Furthermore, a significant inverse correlation was observed between the extent of T cell regulation in suppressor assays and the level of lupus disease activity. Conclusion This study is the first to show that, in human SLE, impaired sensitivity of Tresp cells to the suppressive effects of a comparably functional, highly purified nTreg cell population leads to a defective suppression of T cell proliferation in active SLE. Studies aiming to define the mechanisms leading to Tresp cell resistance might help in the development of highly specific, alternative immunotherapeutic tools for the control of systemic autoimmune diseases such as SLE. [source]

Dysfunctional CD4+,CD25+ regulatory T cells in untreated active systemic lupus erythematosus secondary to interferon-,,producing antigen-presenting cells

ARTHRITIS & RHEUMATISM, Issue 3 2008
Bing Yan
Objective To explore whether there are extrinsic factors that impair the suppressive function of CD4+,CD25+ regulatory T cells in patients with untreated active systemic lupus erythematosus (SLE). Methods We studied 15 patients with untreated active SLE, 10 patients with SLE in remission, and 15 healthy control subjects. Percentages of CD4+,CD25+,FoxP3+ Treg cells and levels of forkhead box P3 (FoxP3) protein were analyzed by flow cytometry. Expression of messenger RNA (mRNA) for FoxP3 in purified Treg cell populations was assessed by real-time polymerase chain reaction analysis. Experiments examining Treg cell function in SLE were designed to distinguish primary from secondary T cell dysfunction. Levels of interferon-, (IFN,) in supernatants from the function assays were determined with an IFN-stimulated response element,luciferase reporter assay. Results The percentage of CD4+,CD25+, FoxP3+ cells in peripheral blood was significantly increased in SLE patients as compared with controls (mean ± SEM 9.11 ± 0.73% versus 4.78 ± 0.43%; P < 0.0001). We found no difference in FoxP3 expression at either the mRNA or protein level in any CD4+,CD25+ T cell subset from SLE patients as compared with controls. Antigen-presenting cells (APCs) from SLE patients were responsible for decreased Treg cell activity and could also render dysfunctional Treg cells from healthy control subjects. CD4+,CD25+ Treg cells from SLE patients exhibited normal suppressive activity when cultured with APCs from healthy controls. A partial Treg cell blockade effect was induced by the high levels of IFN, derived from SLE patient APCs. Conclusion We suggest that blockade of Treg cell,mediated suppression by IFN,-producing APCs in SLE patients may contribute to a pathogenic loss of peripheral tolerance in this disease. [source]

Proinflammatory mediator,induced reversal of CD4+,CD25+ regulatory T cell,mediated suppression in rheumatoid arthritis

ARTHRITIS & RHEUMATISM, Issue 3 2007
Jocea M. R. van Amelsfort
Objective We previously demonstrated that CD4+,CD25+ regulatory T (Treg) cells are present in increased numbers in the synovial fluid (SF) of rheumatoid arthritis (RA) patients and display enhanced suppressive activity as compared with their peripheral blood (PB) counterparts. Despite the presence of these immunoregulatory cells in RA, chronic inflammation persists. The purpose of the present study was to investigate whether particular proinflammatory mediators that are associated with RA could abrogate CD4+,CD25+ Treg,mediated suppression. Methods Monocyte phenotype was determined by flow cytometry and cytokine levels by enzyme-linked immunosorbent assay. Magnetically sorted CD4+,CD25, and CD4+,CD25+ T cells derived from the PB and SF obtained from RA patients were stimulated alone or in coculture with anti-CD3 monoclonal antibody (mAb) and autologous antigen-presenting cells, in the absence or presence of anti-CD28 mAb or the proinflammatory cytokines interleukin-6 (IL-6), tumor necrosis factor , (TNF,), or IL-7. Results Monocytes from the SF of RA patients displayed increased expression of HLA class II molecules, CD80, CD86, and CD40 as compared with PB-derived monocytes, indicating their activated status. Mimicking this increased costimulatory potential, addition of anti-CD28 mAb to cocultures of CD4+,CD25, and CD4+,CD25+ T cells resulted in reduced CD4+,CD25+ Treg,mediated suppression in both PB and SF. Furthermore, IL-7 and, to a limited extent, TNF,, both of which are produced by activated monocytes and were detected in SF, abrogated the CD4+,CD25+ Treg,mediated suppression. In contrast, IL-6 did not influence Treg-mediated suppression. Conclusion Our findings suggest that the interaction of CD4+,CD25+ Treg cells with activated monocytes in the joint might lead to diminished suppressive activity of CD4+,CD25+ Treg cells in vivo, thus contributing to the chronic inflammation in RA. [source]

Frequencies and role of regulatory T cells in patients with (pre)malignant cervical neoplasia

CLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 2 2007
J. Visser
Summary Oncogenic human papillomavirus (HPV)-infection is crucial for developing cervical cancer and its precursor lesions [cervical intraepithelial neoplasia (CIN)]. Regulatory T cells (Tregs) might be involved in the failure of the immune system to control the development of HPV-induced cancer. We investigated frequencies, phenotype and activity of Tregs in patients with cervical neoplasia. CIN and cervical cancer patients showed increased CD4+/CD25high T cell frequencies in peripheral blood and CD4+ T cell fraction. These CD4+/CD25high T cells represent Tregs as demonstrated by their low proliferation rate, low interferon (IFN)-,/interleukin (IL)-10 ratio, high expression of CD45RO, GITR, CTLA-4, forkhead box P3 (FoxP3) and low CD45RA expression. Moreover, in HPV16+ cervical cancer patients, in-vitro depletion of CD25+ T cells resulted in increased IFN-, T cell responses against HPV16 E6- and E7 peptides. Thus, increased frequencies of Tregs in cervical cancer patients may indeed suppress HPV-specific immunity. Longitudinal analysis of CD4+/CD25high T cell frequencies in patients showed a modest decline 1 year after curative surgery or chemoradiation. This study demonstrates increased frequencies and suppressive activity of Tregs in cervical cancer. These results imply that Tregs may suppress the immune control of cervical neoplasia and furthermore that suppression of immunity by Tregs will be another hurdle to overcome in therapeutic immunization strategies against cervical neoplasia. [source]