CD4+CD25bright regulatory T cells actively regulate inflammation in the joints of patients with the remitting form of juvenile idiopathic arthritis

This study investigates the role of CD4(+)CD25(+) regulatory T cells during the clinical course of juvenile idiopathic arthritis (JIA). Persistent oligoarticular JIA (pers-OA JIA) is a subtype of JIA with a relatively benign, self-remitting course while extended oligoarticular JIA (ext-OA JIA) is a subtype with a much less favorable prognosis. Our data show that patients with pers-OA JIA display a significantly higher frequency of CD4(+)CD25(bright) T cells with concomitant higher levels of mRNA FoxP3 in the peripheral blood than ext-OA JIA patients. Furthermore, while numbers of synovial fluid (SF) CD4(+)CD25(bright) T cells were equal in both patient groups, pers-OA JIA patients displayed a higher frequency of CD4(+)CD25(int) T cells and therefore of CD4(+)CD25(total) in the SF than ext-OA JIA patients. Analysis of FoxP3 mRNA levels revealed a high expression in SF CD4(+)CD25(bright) T cells of both patient groups and also significant expression of FoxP3 mRNA in the CD4(+)CD25(int) T cell population. The CD4(+)CD25(bright) cells of both patient groups and the CD4(+)CD25(int) cells of pers-OA JIA patients were able to suppress responses of CD25(neg) cells in vitro. A markedly higher expression of CTLA-4, glucocorticoid-induced TNFR, and HLA-DR on SF CD4(+)CD25(bright) T regulatory (Treg) cells compared with their peripheral counterparts suggests that the CD4(+)CD25(+) Treg cells may undergo maturation in the joint. In correlation with this mature phenotype, the SF CD4(+)CD25(bright) T cells showed an increased regulatory capacity in vitro compared with peripheral blood CD4(+)CD25(bright) T cells. These data suggest that CD4(+)CD25(bright) Treg cells play a role in determining the patient's fate toward either a favorable or unfavorable clinical course of disease.     

SLE带状疱疹患者外周血CD4~+CD28~+和CD4~+CD25~+FoxP3~+调节性T细胞的表达及相关性研究

目的:检测系统性红斑狼疮(systemic lupus erythematosus,SLE)合并带状疱疹患者外周血CD4~+CD28~+和CD4~+CD25~+Fox P3~+调节性T细胞的表达及相关性,探讨其在SLE合并带状疱疹发病中的临床意义。方法:采用流式细胞术检测30例SLE患者、30例SLE合并带状疱疹患者及30例健康对照者外周血中CD4~+/CD8~+T淋巴细胞亚群表面CD28的表达及CD4~+CD25~+Fox P3~+Treg细胞的表达水平,并分析SLE合并带状疱疹患者外周血CD4~+CD28~+和CD4~+CD25~+Fox P3~+调节性T细胞表达的相关性。结果:SLE合并带状疱疹组患者急性期外周血CD4~+T淋巴细胞比率、绝对计数显著降低,CD4~+、CD8~+T淋巴细胞表面的CD28表达下调,CD4~+CD25~+Fox P3~+Treg细胞水平显著高于SLE组及健康对照组,SLE合并带状疱疹组患者外周血CD4~+CD25~+Fox P3~+Treg水平与CD4~+CD28~+水平成负相关(P均0.05)。结论:SLE合并带状疱疹患者CD4~+、CD8~+T细胞活化异常,CD4~+CD25~+Fox P3~+Treg细胞可能参与抑制了T细胞的活化。     

CD4+CD25+ T regulatory cells suppress NK cell-mediated immunotherapy of cancer

CD4+CD25+ regulatory T cells (Treg) that suppress T cell-mediated immune responses may also regulate other arms of an effective immune response. In particular, in this study we show that Treg directly inhibit NKG2D-mediated NK cell cytotoxicity in vitro and in vivo, effectively suppressing NK cell-mediated tumor rejection. In vitro, Treg were shown to inhibit NKG2D-mediated cytolysis largely by a TGF-beta-dependent mechanism and independently of IL-10. Adoptively transferred Treg suppressed NK cell antimetastatic function in RAG-1-deficient mice. Depletion of Treg before NK cell activation via NKG2D and the activating IL-12 cytokine, dramatically enhanced NK cell-mediated suppression of tumor growth and metastases. Our data illustrate at least one mechanism by which Treg can suppress NK cell antitumor activity and highlight the effectiveness of combining Treg inhibition with subsequent NK cell activation to promote strong innate antitumor immunity.     

Protection from type 1 diabetes by invariant NK T cells requires the activity of CD4+CD25+ regulatory T cells

Invariant NK T (iNKT) cells regulate immune responses, express NK cell markers and an invariant TCR, and recognize lipid Ags in a CD1d-restricted manner. Previously, we reported that activation of iNKT cells by alpha-galactosylceramide (alpha-GalCer) protects against type 1 diabetes (T1D) in NOD mice via an IL-4-dependent mechanism. To further investigate how iNKT cells protect from T1D, we analyzed whether iNKT cells require the presence of another subset(s) of regulatory T cells (Treg), such as CD4+ CD25+ Treg, for this protection. We found that CD4+ CD25+ T cells from NOD.CD1d(-/-) mice deficient in iNKT cell function similarly in vitro to CD4+ CD25+ T cells from wild-type NOD mice and suppress the proliferation of NOD T responder cells upon alpha-GalCer stimulation. Cotransfer of NOD diabetogenic T cells with CD4+ CD25+ Tregs from NOD mice pretreated with alpha-GalCer demonstrated that activated iNKT cells do not influence the ability of T(regs) to inhibit the transfer of T1D. In contrast, protection from T1D mediated by transfer of activated iNKT cells requires the activity of CD4+ CD25+ T cells, because splenocytes pretreated with alpha-GalCer and then inactivated by anti-CD25 of CD25+ cells did not protect from T1D. Similarly, mice inactivated of CD4+ CD25+ T cells before alpha-GalCer treatment were also not protected from T1D. Our data suggest that CD4+ CD25+ T cells retain their function during iNKT cell activation, and that the activity of CD4+ CD25+ Tregs is required for iNKT cells to transfer protection from T1D.     

CD4+CXCR4highCD69+ T cells accumulate in lung adenocarcinoma

The chemokine receptor CXCR4 is involved in the growth and metastasis of tumor cells. However, the expression of its ligand, the chemokine CXCL12, in tumors and its role in regulating the accumulation of immune cells within the tumors is not clear. Using ELISA and immunohistochemistry we found that CXCL12 is expressed in the majority of nonsmall cell lung cancer tissue sections obtained from stage IA to IIB nonsmall cell lung cancer patients undergoing operation. Histopathologic examination of these sections indicated that high CXCL12 expression correlated with increased tumor inflammation. In addition, disease recurrence rates in a subgroup of adenocarcinoma patients showed a tendency to correlate with high CXCL12 expression in the tumor. Isolation of adenocarcinoma-infiltrating immune cells demonstrated an increase in the percentage of CD4+CD69+CXCR4+ T cells as compared with normal lung tissue. About 30% of these cells expressed the regulatory T cell markers CD25high and FoxP3. The percentage of CD8 T cells within the tumor did not change, however; the percentage of NK and NK T cells was significantly reduced. In correlation with CXCR4 expression, CD4 T cells showed increased migration in response to CXCL12 compared with CD8 T cells and NK cells. Overall, these observations suggest that CXCL12 expression may influence tumor progression by shaping the immune cell population infiltrating lung adenocarcinoma tumors.     

Human CD4+ T cells express TLR5 and its ligand flagellin enhances the suppressive capacity and expression of FOXP3 in CD4+CD25+ T regulatory cells

Germline encoded pattern recognition receptors, such as TLRs, provide a critical link between the innate and adaptive immune systems. There is also evidence to suggest that pathogen-associated molecular patterns may have the capacity to modulate immune responses via direct effects on CD4+ T cells. Given the key role of both CD4+CD25+ T regulatory (Treg) cells and the TLR5 ligand flagellin in regulating mucosal immune responses, we investigated whether TLR5 may directly influence T cell function. We found that both human CD4+CD25+ Treg and CD4+CD25- T cells express TLR5 at levels comparable to those on monocytes and dendritic cells. Costimulation of effector T cells with anti-CD3 and flagellin resulted in enhanced proliferation and production of IL-2, at levels equivalent to those achieved by costimulation with CD28. In contrast, costimulation with flagellin did not break the hyporesponsiveness of CD4+CD25+ Treg cells, but rather, potently increased their suppressive capacity and enhanced expression of FOXP3. These observations suggest that, in addition to their APC-mediated indirect effects, TLR ligands have the capacity to directly regulate T cell responses and modulate the suppressive activity of Treg cells.     

Effect of medical castration on CD4+ CD25+ T cells, CD8+ T cell IFN-gamma expression, and NK cells: a physiological role for testosterone and/or its metabolites

The higher prevalence of autoimmune disease among women compared with men suggests that steroids impact immune regulation. To investigate how sex steroids modulate cellular immune function, we conducted a randomized trial in 12 healthy men aged 35-55 yr treated for 28 days with placebo, a GnRH antagonist, acyline to induce medical castration, or acyline plus daily testosterone (T) gel to replace serum T, followed by a 28-day recovery period. Serum hormones were measured weekly and peripheral blood lymphocytes (PBLs) were collected biweekly for analyses of thymus-derived lymphocyte (T cell) subtypes and natural killer (NK) cells. Compared with the other groups and to baseline throughout the drug exposure period, men receiving acyline alone had significant reductions in serum T (near or below castrate levels), dihydrotestosterone, and estradiol (P < 0.05). Medical castration significantly reduced the percentage of CD4+ CD25+ T cells (P < 0.05), decreased mitogen-induced CD8+ T cell IFN-gamma expression, and increased the percentage of NK cells without affecting the ratio of CD4+ to CD8+ T cells and the expression of NK cell-activating receptor NKG2D or homing receptor CXCR1. No changes in immune composition were observed in subjects receiving placebo or acyline with replacement T. These data suggest that T and/or its metabolites may help maintain the physiological balance of autoimmunity and protective immunity by preserving the number of regulatory T cells and the activation of CD8+ T cells. In addition, sex steroids suppress NK cell proliferation. This study supports a complex physiological role for T and/or its metabolites in immune regulation.     

CD39 is highly involved in mediating the suppression activity of tumor-infiltrating CD8+ T regulatory lymphocytes

CD39 is an ectoenzyme, present on different immune cell subsets, which mediates immunosuppressive functions catalyzing ATP degradation. It is not known whether CD39 is expressed and implicated in the activity of CD8+ regulatory T lymphocytes (Treg). In this study, CD39 expression and function was analyzed in both CD8+ and CD4+CD25^hi Treg from the peripheral blood of healthy donors as well as from tumor specimens. CD39 was found expressed by both CD8+ (from the majority of healthy donors and tumor patients) and CD4+CD25^hi Treg, and CD39 expression correlated with suppression activity mediated by CD8+ Treg. Importantly, CD39 counteraction remarkably inhibited the suppression activity of CD8+ Treg (both from peripheral blood and tumor microenvironment) suggesting that CD39-mediated inhibition constitutes a prevalent hallmark of their function. Collectively, these findings, unveiling a new mechanism of action for CD8+ Treg, provide new knowledge on intratumoral molecular pathways related to tumor immune escape, which could be exploited in the future for designing new biological tools for anticancer immune intervention.     

CD4dimCD25bright Treg cell frequencies above a standardized gating threshold are similar in asthmatics and controls.

BACKGROUND: Thymus selected CD4(+)CD25(bright) natural regulatory Treg cells expressing FOXP3 may contribute to control of immune responses. No unique markers have been available to identify and characterize Treg. We present a gating strategy that allows enumeration of Treg on the basis of CD4 and CD25 and investigate whether asthmatics have fewer Treg than controls. METHODS: Asthmatics and controls were selected from responses to a mailed questionnaire. CD25, CD4, HLA DR, and appropriate isotypes were recorded by flow cytometry. RESULTS: The CD4 T cells expressing most CD25 are a separate population expressing FOXP3 and lower levels of CD4 and CD127. On a CD4 CD25 dot-plot, the CD4 MFI of Treg for 152 participants was calculated to be 0.83 +/- 0.043*MFI of CD25(bright) T-cells. CD4(dim)CD25(bright) T cells in a rectangular gate with a CD4 MFI 相似文献   

CTLA-4 and CD4+ CD25+ regulatory T cells inhibit protective immunity to filarial parasites in vivo

The T cell coinhibitory receptor CTLA-4 has been implicated in the down-regulation of T cell function that is a quintessential feature of chronic human filarial infections. In a laboratory model of filariasis, Litomosoides sigmodontis infection of susceptible BALB/c mice, we have previously shown that susceptibility is linked both to a CD4+ CD25+ regulatory T (Treg) cell response, and to the development of hyporesponsive CD4+ T cells at the infection site, the pleural cavity. We now provide evidence that L. sigmodontis infection drives the proliferation and activation of CD4+ Foxp3+ Treg cells in vivo, demonstrated by increased uptake of BrdU and increased expression of CTLA-4, Foxp3, GITR, and CD25 compared with naive controls. The greatest increases in CTLA-4 expression were, however, seen in the CD4+ Foxp3- effector T cell population which contained 78% of all CD4+ CTLA-4+ cells in the pleural cavity. Depletion of CD25+ cells from the pleural CD4+ T cell population did not increase their Ag-specific proliferative response in vitro, suggesting that their hyporesponsive phenotype is not directly mediated by CD4+ CD25+ Treg cells. Once infection had established, killing of adult parasites could be enhanced by neutralization of CTLA-4 in vivo, but only if performed in combination with the depletion of CD25+ Treg cells. This work suggests that during filarial infection CTLA-4 coinhibition and CD4+ CD25+ Treg cells form complementary components of immune regulation that inhibit protective immunity in vivo.     

CD13+CD4+CD25hi regulatory T cells exhibit higher suppressive function and increase with tumor stage in non-small cell lung cancer patients

Regulatory T cells (Tregs) in peripheral blood and tumor infiltrating lymphocytes (TILs) play crucial roles in suppressing anti-tumor immune responses in cancer patients, and correlate with clinical outcomes. We identified an important subpopulation, CD13+CD4+CD25hiTreg cells, among CD4+CD25hiTreg cells in the peripheral blood of non-small cell lung cancer (NSCLC) patients. Peripheral blood mononuclear cells (PBMCs) were isolated from patients with NSCLC (n=72) or from healthy donors (n=30). Flow cytometric analyses were performed to study the expression of cell-surface or intracellular markers on the CD4+CD25hiTreg cells. The immune suppressive function of CD13+CD4+CD25hiTreg cells was evaluated by co-culturing with CD4+CD25-T cells that were activated by PHA. Our data showed that, compared with CD4+CD25Low/-T cells, CD13 expression was enriched on CD4+CD25hiTreg cells. The CD13+CD4+CD25hiTreg cells also expressed higher levels of Foxp3, CTLA-4, membrane-bound transforming growth factor β1 (mTGF-β1) and B7-H1, and are more suppressive to CD25 expression and proliferation of CD4+CD25-T cells. Additionally, we showed that the expression of Foxp3, CTLA-4, B7-H1, mTGF-β1 and the secretion of TGF-β1 and IL-10 on CD13+CD4+CD25hiTreg cells was significantly suppressed by anti-CD13 mAb (WM15), and the ability of these cells to suppress CD25 expression and proliferation of CD4+CD25-T cells was inhibited by WM15 as well. Interestingly, the percentage of CD13+CD4+CD25hiTreg cells among the CD4+CD25hiTreg population increased significantly and correlated with pathological stage in NSCLC: healthy donor (9.84%±2.23%) < stage I (21.64%±2.78%) < stage II (31.86%±3.01%) < stage III (45.64%±6.12%) < stage IV (58.78%±12.89%). Moreover, the percentage of CD13+CD4+CD25hiTreg cells decreased dramatically after surgical removal of tumors. CD13 is a new surface molecule for identifying a CD4+CD25hiTreg cell subpopulation with higher suppressive ability. The percentage of CD13+CD4+CD25hiTreg cells among the CD4+CD25hiTreg cell population correlated with the pathological stage in NSCLC and tumor burden. CD13 represents a potential target to suppress Treg cells in anti-tumor therapy.     

The majority of human peripheral blood CD4+CD25highFoxp3+ regulatory T cells bear functional skin-homing receptors

CD4+CD25+ T regulatory cells (Treg) are thought to be important in the peripheral tolerance. Recent evidence suggests that human peripheral blood CD4+CD25+ T cells are heterogeneous and contain both CD4+CD25(high) T cells with potent regulatory activity and many more CD4+CD25(low/med) nonregulatory T cells. In this study, we found that virtually all peripheral blood CD4+CD25(high)Foxp3+ Treg expressed high levels of the chemokine receptor CCR4. In addition, 80% of Treg expressed cutaneous lymphocyte Ag (CLA) and 73% expressed CCR6. These molecules were functional, as CLA+ Treg showed CD62E ligand activity and demonstrable chemotactic responses to the CCR4 ligands CCL22 and CCL17 and to the CCR6 ligand CCL20. The phenotype and chemotactic response of these Treg were significantly different from those of CD4+CD25(med) nonregulatory T cells. We further demonstrated that blood CLA+ Treg inhibited CD4+CD25- T cell proliferation induced by anti-CD3. Based on homing receptor profile, CLA+ Treg should enter normal skin. We next isolated CD4+CD25(high) T cells directly from normal human skin; these cells suppressed proliferation of skin CD4+CD25- T cells. Therefore, the majority of true circulating Treg express functional skin-homing receptors, and human Treg may regulate local immune responses in normal human skin.     

CD4+CD25hiCD127low Regulatory T Cells Are Increased in Oral Squamous Cell Carcinoma Patients

Regulatory T cells (Tregs), a subset of CD4⁺ T cells plays a pivotal role in regulating the immune system. An increase in Treg numbers enables cancer progression by dampening the immune system and allowing tumor cells to evade immune detection and destruction. An increase in Treg numbers and expression of inhibitory cytokines including TGF-β and IL-10 are mechanisms by which Tregs exert their immune suppressive function. However, the presence of Tregs and inhibitory cytokines in oral cancer patients is still unclear. In this study, the presence of circulating Tregs in 39 oral cancer patients and 24 healthy donors was examined by studying the presence of the CD4⁺CD25^hiCD127^low cell population in their peripheral blood mononuclear cells using flow cytometry. Serum levels of TGF-β and IL-10 were measured by ELISA. T cell subsets of OSCC patients were found to differ significantly from healthy donors where a decrease in CD8⁺ cytotoxic T cells and an increase in Tregs (CD4⁺CD25^hiCD127^low) were observed. Further, the ratio of CD8⁺ T cells/Tregs was also decreased in patients compared to healthy donors. The presence of Tregs was accompanied by a decrease in IL-10 but not TGF-β secretion in OSCC patients when compared to donors; in addition, the analysis also revealed that an increased presence of Tregs was accompanied by better patient survival. Amongst OSCC patients, smokers had significantly higher levels of TGF-β. It is apparent that the immune system is compromised in OSCC patients and the characterization of the Treg subpopulation could form a basis for improving our understanding of the perturbations in the immune system that occur during OSCC tumorigenesis.     

Circulating and liver resident CD4+CD25+ regulatory T cells actively influence the antiviral immune response and disease progression in patients with hepatitis B

CD4+CD25+ regulatory T cells (Treg) have been shown to maintain immune tolerance against self and foreign Ags, but their role in persistent viral infection has not been well-defined. In this study, we investigated whether and where CD4+CD25+ Treg contribute to the development of chronic hepatitis B (CHB). One hundred twenty-one patients were enrolled, including 16 patients with acute hepatitis B, 76 with CHB, and 29 with chronic severe hepatitis B. We demonstrated that in chronic severe hepatitis B patients, the frequencies of CD4+CD25+ Treg in both PBMC and liver-infiltrating lymphocytes were significantly increased and there was a dramatic increase of FoxP3(+)-cell and inflammatory cell infiltration in the liver compared with healthy controls. In CHB patients, circulating CD4+CD25+ Treg frequency significantly correlates with serum viral load. In acute hepatitis B patients, circulating CD4+CD25+ Treg frequency was initially low and with time, the profile reversed to exhibit an increased number of circulating Treg in the convalescent phase and restored to normal levels upon resolution. In PBMC taken from infected patients, depletion of CD4+CD25+ Treg led to an increase of IFN-gamma production by HBV-Ag-stimulated PBMC. In addition, CD4+CD25+ Treg were capable of suppressing proliferation of autologous PBMC mediated by HBV Ags, which probably reflects the generation of HBV-Ag-specific Treg in circulation and in the liver of HBV-infected patients. Together, our findings suggest that CD4+CD25+ Treg play an active role not only in modulating effectors of immune response to HBV infection, but also in influencing the disease prognosis in patients with hepatitis B.     

Immune modulation of effector CD4+ and regulatory T cell function by sorafenib in patients with hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a difficult to treat cancer characterized by poor tumor immunity with only one approved systemic drug, sorafenib. If novel combination treatments are to be developed with immunological agents, the effects of sorafenib on tumor immunity are important to understand. In this study, we investigate the impact of sorafenib on the CD4+CD25? effector T cells (Teff) and CD4+CD25+ regulatory T cells (Tregs) from patients with HCC. We isolated Teff and Treg from peripheral mononuclear cells of HCC patients to determine immune reactivity by thymidine incorporation, ELISA and flow cytometry. Teff cultured alone or with Treg were supplemented with different concentrations of sorafenib. The effects of sorafenib on Teff responses were dose-dependent. Pharmacologic doses of sorafenib decreased Teff activation by down regulating CD25 surface expression. In contrast, sub-pharmacologic concentrations of sorafenib resulted in Teff activation. These low doses of sorafenib in the Teff cultures led to a significant increase in Teff proliferation, IL2 secretion and up-regulation of CD25 expression on the cell surface. In addition, low doses of sorafenib in the suppression Teff/Treg cocultures restored Teff responses by eliminating Treg suppression. The loss of Treg suppressive function correlated with an increase in IL2 and IL6 secretion. Our findings show that sub-pharmacologic doses of sorafenib impact subsets of T cells differently, selectively increasing Teff activation while blocking Treg function. In conclusion, this study describes novel immune activating properties of low doses of sorafenib by promoting immune responsiveness in patients with HCC.     

Guarding the immune system: suppression of autoimmunity by CD4+CD25+ immunoregulatory T cells

CD4+CD25+Foxp3+ T cells (CD25+ T regulatory [Treg] cells) are a naturally occurring suppressor T-cell population that regulates a wide variety of immune responses. A major function of CD25+ Treg cells is to inhibit the activity of self-reactive T cells that can potentially cause autoimmune disease. This review examines the recent advances in CD25+ Treg cell biology, with particular focus on the thymic and peripheral development of CD25+ Treg cells, the signals that promote their expansion and maintenance in the periphery and the mechanism by which they mediate their suppressor activity in peripheral lymphoid tissues. An understanding of these issues is likely to facilitate the development of CD25+ Treg-cell-based therapies for the treatment of autoimmune disease.     

In vitro expansion of CD4+CD25highFOXP3+CD127low/- regulatory T cells from peripheral blood lymphocytes of healthy Mycobacterium tuberculosis-infected humans

CD4+CD25highFOXP3+ regulatory T (Treg) cells have recently been found at elevated levels in the peripheral blood of tuberculosis patients, compared to Mycobacterium tuberculosis latently infected (LTBI) healthy individuals and non-infected controls. Here, we show that CD4+CD25highFOXP3+ T lymphocytes can be expanded in vitro from peripheral blood mononuclear cells (PBMC) of LTBI individuals, but not of uninfected controls by incubating them with BCG in the presence of TGF-beta. These expanded cells from the PBMC of LTBI subjects expressed CTLA-4, GITR and OX-40, but were CD127low/- and have therefore the phenotype of Treg cells. In addition, they inhibited in a dose-dependant manner the proliferation of freshly isolated mononuclear cells in response to polyclonal stimulation, indicating that they are functional Treg lymphocytes. In contrast, incubation of the PBMC with BCG alone preferentially induced activated CD4+ T cells, expressing CD25 and/or CD69 and secreting IFN-gamma. These results show that CD4+CD25highFOXP3+ Treg cells can be expanded or induced in the peripheral blood of LTBI individuals in conditions known to predispose to progression towards active tuberculosis and may therefore play an important role in the pathogenesis of the disease.     

Functional study of CD4+CD25+ regulatory T cells in health and autoimmune hepatitis

Regulatory CD4(+)CD25(+) T cells (Tregs) are defective numerically and functionally in autoimmune hepatitis (AIH). We have investigated and compared the mechanism of action of Tregs in healthy subjects and in AIH patients using Transwell experiments, where Tregs are cultured either in direct contact with or separated from their targets by a semipermeable membrane. We also studied Treg FOXP3 expression and effect on apoptosis. Direct contact is necessary for Tregs to suppress proliferation and IFN-gamma production by CD4(+)CD25(-) and CD8(+) T cells in patients and controls. Moreover, in both, direct contact of Tregs with their targets leads to increased secretion of regulatory cytokines IL-4, IL-10, and TGF-beta, suggesting a mechanism of linked immunosuppression. Tregs/CD4(+)CD25(-) T cell cocultures lead to similar changes in IFN-gamma and IL-10 secretion in patients and controls, whereas increased TGF-beta secretion is significantly lower in patients. In contrast, in patients, Tregs/CD8(+) T cell cocultures lead to a higher increase of IL-4 secretion. In AIH, Treg FOXP3 expression is lower than in normal subjects. Both in patients and controls, FOXP3 expression is present also in CD4(+)CD25(-) T cells, although at a low level and not associated to suppressive function. Both in patients and controls, addition of Tregs does not influence target cell apoptosis, but in AIH, spontaneous apoptosis of CD4(+)CD25(-) T cells is reduced. In conclusion, Tregs act through a direct contact with their targets by modifying the cytokine profile and not inducing apoptosis. Deficient CD4(+)CD25(-) T cell spontaneous apoptosis may contribute to the development of autoimmunity.     

Lipopolysaccharide-activated CD4+CD25+ T regulatory cells inhibit neutrophil function and promote their apoptosis and death

CD4+CD25+ T regulatory (Treg) cells play a central role in the suppression of immune response and prevention of autoimmune reactions. Pathogen recognition receptors expressed by immune cells, such as TLRs, may provide a critical link between the innate and adaptive immune systems. There is also evidence that TLR ligands can directly modulate the suppressive capacity of Treg cells. Here, we showed that CD4+CD25+ Treg cells affect neutrophil function and survival and that the TLR4 ligand is involved in the regulation of the cell interactions. We found that LPS-activated Treg cells inhibit reactive oxygen intermediates and cytokine production by neutrophils. Moreover, Treg cells reverse LPS-induced survival of neutrophils and promote their apoptosis and death. We also found that TCR-activated Treg cells induce the same effects on polymorphonuclear neutrophils as those achieved by TLR4 stimulation. Importantly, the suppressive potential of CD4+CD25+ Treg cells induced by LPS seems to be partially IL-10 and TGF-beta dependent, whereas anti-CD3/CD28 stimulation is rather contact dependent. Together, these observations suggest that Treg cells have the ability to directly regulate neutrophil function and life span when both types of the cells are exposed to LPS.