CD4 CD25 Treg Research Articles

Expression of microRNA-155 and regulative T cell in sepsis patients and their relationship

To investigate the adjustment effect of microRNA-155 on CD4(+)CD25(+) regulative T cell (Treg) in peripheral blood of sepsis patients, and to elucidate the role of miR-155 in the pathogenesis of sepsis. A retrospective study was conducted. 60 sepsis patients (mild n=20, moderate n=20, and severe n=20) from emergency room or intensive care unit (ICU) of the Fourth Hospital of Jiangsu University were enrolled. 20 healthy volunteers were enrolled as controls. Real-time fluorescent quantitation polymerase chain reaction (qRT-PCR) was used to detect the levels of miR-155 and Foxp3 mRNA expressions in peripheral blood. CD4(+)CD25(+) Treg cells in peripheral blood were identified by flow cytometry. Peripheral interleukin-10 (IL-10) was measured by enzyme-linked immunosorbent assay (ELISA). The expressions of miR-155, Treg, Foxp3 mRNA and the level of IL-10 were higher in the patients with sepsis than those in healthy control group [Treg: (2.89±1.13)% vs. (2.32±0.91)%, t=10.540, P=0.002; miR-155: 1.19±0.48 vs. 0.80±0.33, t=8.605, P=0.006; Foxp3 mRNA: 0.18±0.08 vs. 0.13±0.03, t=6.862, P=0.008; IL-10: 56.89±17.28 ng/L vs. 33.24±11.93 ng/L, t=12.742, P=0.001]. These variables were elevated gradually with the elevation of acute physiology and chronic health evaluation II (APACHEII) score. The expressions of Treg, miR-155, Foxp3 mRNA and the level of IL-10 were (3.05±1.21)%, 1.36±0.79, 0.21±0.10, (62.82±21.38) ng/L in severe sepsis group; they were (2.86±0.88)%, 1.25±0.56, 0.17±0.08, (56.38±19.65) ng/L in moderate group; they were (2.61±0.87)%, 0.94±0.52, 0.15±0.05, (45.43±14.40) ng/L in mild group. The values showed significant statistical difference among the mild, moderate and severe sepsis groups (all P<0.01). Above values were significantly higher in non-survival group than those in survival group [Treg: (3.46±1.53)% vs. (2.85±1.03)%, t=14.250, P=0.005; miR-155: 1.41±0.85 vs. 1.16±0.76, t=11.875, P=0.006; Foxp3 mRNA: 0.24±0.11 vs. 0.17±0.09, t=8.795,P=0.001; IL-10: 65.47±23.58 ng/L vs. 51.70±16.86 ng/L, t=16.313, P=0.001]. The expression of miR-155 was positively correlated with the expression of CD4(+)CD25(+) Treg and Foxp3 mRNA (r 1=0.635, P 1=0.007; r 2=0.671, P 2=0.005). The result of this study suggest that miR-155 is involved in the cell proliferation regulation of CD4(+)CD25(+) Treg cells, and play some role in the immunological dissonance in sepsis.

Immunomodulatory effect of UC-MSC on function of immunocytes of rats with collagen type II induced arthritis

This study was purposed to observe the influence of umbilical cord mesenchymal stem cells (UC-MSC) on the peripheral blood CD4(+)CD25(+)regulatory T cells (Treg), Th17 cells and neutrophils in rats with collagen type II-induced arthritis(CIA), and to explore the regulating effect of UC-MSC transplantation on immunocyte subgroup. The rats wee divided into 3 groups: CIA group (model group), UC-MSC treated group and blank control group. The CIA rats were injected with UC-MSC via tail vein. The percentage of CD4(+)CD25(+) cells in peripheral blood and the expression of NCD11b on neutrophil surface in CIA rates was detected by flow cytometry (FCM), and the serum interleukin-17 (IL-17) was observed by enzyme-linked immunosorbent assay (ELISA). The results showed that the mean fluorescence intensity(MFI) of NCD11b and the level of IL-17 in the model group were significantly higher than those in the blank control group, and the ratio of CD4(+)CD25(+) cells were significantly lower (P < 0.05). The MIF of NCD11b and the level of IL-17 in the UC-MSC treated group were significantly lower than that in the model group (P < 0.05), while the proportion of CD4(+)CD25(+) Treg increased (P < 0.05). Since the fifth week, the above indicators in the UC-MSC group have almostly approached the control group. It is concluded that the UC-MSC can increase peripheral blood Treg proportion in CIA rat, inhibit the secretion of Th17 and the activity of neutrophils, reduce the immune inflammation reaction, decrease the release of proinflammatory factor, and induce immune reconstruction.

Effect of narrow band‐ultraviolet B on CD4+CD25highFoxP3+T‐lymphocytes in the peripheral blood of vitiligo patients

It is widely believed that an imbalance between activated CD8(+) T cells and regulatory T cells (Tregs) exists in patients with vitiligo. Although there is evidence that narrow band ultraviolet (NB-UVB) irradiation can induce Tregs' number and activity, but up to our knowledge, none of the published studies involved the possible effect of NB-UVB on Tregs in vitiligo. To evaluate the effect of NB-UVB on circulating CD4(+) CD25(high) FoxP3(+) regulatory T cells (FoxP3(+) Tregs) in vitiligo. This prospective analytic study included 20 patients with active non-segmental vitiligo and 20 healthy controls. The patients were exposed to NB-UVB therapy three times per week for 30 sessions. Blood sampling before and after NB-UVB phototherapy was done to evaluate circulating CD4(+) CD25(high) Tregs and Foxp3(+) Tregs. The CD4(+) CD25(high) Tregs% and FoxP3(+) Tregs% were significantly higher in vitiligo patients compared with controls. NB-UVB therapy decreased both of them in patients, but they did not reach those of controls. Each of circulating CD4(+) CD25(high) Tregs% and FoxP3(+) Tregs% didn't correlate with either extent or activity of vitiligo before or after NB-UVB. Tregs functional defect is probably having an impact on NSV. NB-UVB may improve the function of Tregs. Understanding the mechanisms through which NB-UVB exert its effect on reducing the number of circulating Tregs would help open up the paths for future therapeutic options.

CD4(+)CD25(+) regulatory T cells as a therapeutic target in rheumatoid arthritis.

CD4+CD25+ T cells are regulatory T cells (CD4+CD25+ Tregs), which can strengthen immune tolerance. They play a critical role in controlling the development of autoimmune diseases in animals and humans. Rheumatoid arthritis (RA) is a chronic autoimmune disease that affects the peripheral joints and eventually leads to joint destruction. Although the pathogenesis of RA remains unknown, it is supposed to be affected by autoreactive T cells and antibodies. At the same time, to make the CD4+CD25+ T cells active and to increase the number of the cells are responsible in the therapy of RA in recent studies. Now, many techniques about expansion of Tregs in vitro have been established to overcome the problem of their limited numbers in vivo. It is important to carry out a study of induction or amplification of Tregs in vitro. Here, we review our current understanding of CD4+CD25+ T cells in RA and the targeting of these cells in RA therapy.

Higher frequency of CD4+CD25high Treg cells in hemophilia patients with factor VIII inhibitor

The production of factor VIII inhibitor antibodies remains the most costly and serious complication in replacement therapy of hemophilia A. We investigated the clinical significance of CD4(+)CD25(high) T regulatory (Treg) cells in hemophilia patients. Our trial included 6 severe hemophilia A patients with factor VIII inhibitors, 6 hemophilia patients without inhibition of factor VIII, and 6 healthy persons (controls). Plasma factor VIII: c was measured by clotting assay. Peripheral blood samples were examined using mutiparameter flow cytometry with fluorescent-labeled monoclonal antibodies. Plasma levels of IFN-γ, IL-2, IL-10, and TGF-β were measured by ELISA. The frequency of CD4(+)CD25(high) Treg cells in CD4(+) cells was 1.07 ± 0.38% in inhibitor patients and 0.57 ± 0.14% in non-inhibitor patients. The proportion of Treg cells in healthy controls was similar to that of the non-inhibitor patients. However, there were significant differences between the inhibitor and non-inhibitor patients in levels of IFN-γ, IL-2, IL-10, and TGF-β. We conclude that the proportions of Treg cells and the concentrations of T cell cytokines in inhibitor patients are higher than those in non-inhibitor patients. The increased number of Treg cells and increased T-cell cytokines may be related to the development and efficiency of the factor VIII inhibitor.

Expression of Ets-1 and FOXP3 mRNA in CD4+CD25+ T regulatory cells from patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease with complex genetic predisposing factors involved. Ets-1 transcription factor plays an important role in the suppressive activity of CD4(+)CD25(+) Treg cells and stable expression of FOXP3. To find its potential role in the pathogenesis of SLE, we investigate the mRNA expression of Ets-1 and FOXP3 mRNA in CD4(+)CD25(+) Treg cells from patients with SLE. Real-time transcription-polymerase chain reaction analysis was used to determine the expression of Ets-1 and FOXP3 mRNA in CD4(+)CD25(+) Treg cells from 36 patients with SLE and 18 sex-and-age-matched healthy controls. The Ets-1 mRNA expression level was decreased in patients with SLE [0.225 (0.135, 0.337)] than healthy controls [0.528 (0.303, 0.681)] (P < 0.001). The expression levels of FOXP3 mRNA were lower in SLE patients [0.608 (0.272, 1.164)] than healthy controls [0.919 (0.690, 1.223)], but the difference was not significant (P = 0.106). Significant reduction in Ets-1 and FOXP3 expression was also found in new-onset SLE subgroup when compared with healthy controls (P < 0.001). The level of Ets-1 and FOXP3 mRNA was not significantly different in hyperactive and lower active SLE group when compared with inactive SLE group, respectively (P > 0.05). There were no significant differences between SLE with lupus nephritis (LN) and SLE without LN either (P > 0.05). Associations of Ets-1 and FOXP3 mRNA expression levels with major clinical and laboratory parameters of SLE patients were also analyzed. However, no significant association was found. Significant positive correlation was found between Ets-1 and FOXP3 mRNA expression in CD4(+)CD25(+) Treg cells from SLE patients (r = 0.698, P < 0.001). Our results found that the expression levels of Ets-1 mRNA were decreased in SLE patients and Ets-1 expression was positively correlated with the expression of FOXP3. It indicated that Ets-1 may play an important role in the stable expression of FOXP3 in CD4(+)CD25(+) Treg cells.

In vitro amplification of CD4(+) CD25(+) regulatory T cells and identification of amplified T cell immunosuppressive function

This study was purposed to compare the effect of 3 different cell components for expanding CD4(+) CD25(+) Treg in vitro, and identify their immunosuppressive function. CD4(+) T cells, CD4(+) CD25(-)T cells and CD4(+) CD25(+)T cells were isolated from mouse splenocytes by MACS and then expanded in vitro. Phenotype of the T cell lines and expression of the FOXP3 was determined by flow cytometry. The inhibitory effect of expanded CD4(+) CD25(+) T cells on CD4(+) CD25(-)T cells was tested by MLR method. The results showed that the Treg cells from all the three groups were expanded significantly after culture for 2 weeks. In the CD4(+) T cells group, the proliferation rate was (77.8 ± 5.32) folds with a percentage of Treg cells increasing from (6.61 ± 1.00)% to (15.33 ± 1.31)%. The proliferation rate in the CD4(+) CD25(-) T cells group was (95.20 ± 7.67) folds, with the percentage of CD4(+) CD25(+) T cells raising from (0.37 ± 0.13)% to (9.84 ± 0.98)%. The proliferation rate in the CD4(+) CD25(+) T cells group was (41.20 ± 6.92) folds, the proportion of Treg cells decreased from (86.75 ± 1.25)% to (85.32 ± 1.62)%, and the expression of Foxp3 decreased from (76.92 ± 1.72)% to (75.33 ± 2.11)% during the culture, there were not significant differences in the cell purity and the expression of Foxp3, compared with pre-amplification. The inhibitory test showed that the expanded CD4(+) CD25(+) T cells could inhibit the proliferation of CD4(+) CD25(-) T cells in vitro in a cell dose-dependent manner. It is concluded that the amplification of CD4(+) CD25(+) Treg cells is successful in vitro, especially in the CD4(+) CD25(+) T cells group, the cell purity and Foxp3 gene is not obviously changes after amplification.

Depletion of CD4+ CD25+ regulatory T cells promotes CCL21-mediated antitumor immunity.

CCL21 is known to attract dendritic cells (DCs) and T cells that may reverse tumor-mediated immune suppression. The massive infiltration of tumors by regulatory T cells (Tregs) prevents the development of a successful helper immune response. In this study, we investigated whether elimination of CD4+ CD25+ Tregs in the tumor microenvironment using anti-CD25 monoclonal antibodies (mAbs) was capable of enhancing CCL21-mediated antitumor immunity in a mouse hepatocellular carcinoma (HCC) model. We found that CCL21 in combination with anti-CD25 mAbs (PC61) resulted in improved antitumor efficacy and prolonged survival, not only inhibited tumor angiogenesis and cell proliferation, but also led to significant increases in the frequency of CD4+, CD8+ T cells and CD11c+ DCs within the tumor, coincident with marked induction of tumor-specific CD8+ cytotoxic T lymphocytes (CTLs) at the local tumor site. The intratumoral immune responses were accompanied by the enhanced elaboration of IL-12 and IFN-γ, but reduced release of the immunosuppressive mediators IL-10 and TGF-β1. The results indicated that depletion of Tregs in the tumor microenvironment could enhance CCL21-mediated antitumor immunity, and CCL21 combined with anti-CD25 mAbs may be a more effective immunotherapy to promote tumor rejection.

Role of IL‐10‐producing regulatory B cells in control of cerebral malaria in Plasmodium berghei infected mice

Cerebral malaria (CM) is a neurological syndrome often occurring in severe malaria. Although CM is known as an immunopathology in brain tissue mediated by excessive proinflammatory cytokines, the immunoregulatory mechanism is poorly understood. Here, we investigated the role of IL-10-producing regulatory B (Breg) cells in modulating CM development in a murine model of Plasmodium berghei ANKA infection. We observed that blood-stage P. berghei induced expansion of IL-10-producing Breg cells in C57BL/6 mice. Adoptive transfer of IL-10(+) Breg cells to P. berghei infected mice significantly reduced the accumulation of NK and CD8(+) T cells and hemorrhage in brain tissue, and improved the survival of the mice compared with control groups, although parasitemia levels were not altered. Treatment of Breg-cell recipient mice with anti-IL-10 receptor mAb blocked the protective effect of Breg cells. Adoptive transfer of CD4(+) CD25(+) Treg cells failed to prevent CM in infected mice. Spleen cells from Breg-cell recipient mice produced increased levels of IL-10 in vitro. Cell co-culture showed that purified IL-10(+) B cells, but not IL-10(-) B cells, promoted IL-10 production by CD4(+) T cells. These results demonstrate that IL-10-producing Breg cells may represent an important mechanism for controlling the immunopathology and prevention of CM associated with P. berghei infection.

Expression of blood Th17 and CD4(+) CD25(+) Treg cells in patients with aplastic anemia

This study was aimed to investigate the expression of blood Th17 and CD4(+) CD25(+) regulatory T cells (Treg) in the patients with aplastic anemia (AA). Forty-five patients with AA were enrolled into this study, and were divided into mild aplastic anemia (MAA) group (n = 25) and severe aplastic anemia group (SAA) (n = 20), blood cell count was recorded. 15 healthy donors were enrolled as control. Proportions of blood Th17 and CD4(+) CD25(+) Treg cells were determined by flow cytometry. The serum levels of IL-17, IFN-γ and TNF-α, as well as their concentrations in culture supernatant of phytohemagglutinin (PHA) -stimulated peripheral blood mononuclear cells, were measured by ELISA. The results showed that the proportions of blood Th17 cells and concentration of blood serum IL-17 and IFN-γ increased in patients with SAA, compared with MAA and normal controls, but CD4(+) CD25(+) Foxp3(+) Treg cells obviously decreased in patients with SAA. The concentrations of IL-17 and IFN-γ significantly increased in culture supernatant of SAA group. Hemoglobin level in the patients with AA negatively correlated with the population of Th17 cells and serum IL-17 level, whereas positively correlated with the expression of CD4(+) CD25(+)Treg cells. It is concluded that the increased response of Th17 cells and deficiency of CD4(+) CD25(+) Treg cells present in severe aplastic anemia. The severity of anemia may be related with the imbalance between Th17 and CD4(+) CD25(+)Treg cell response.

Impairment of Regulatory T-Cell Function in Autoimmune Thyroid Disease

Autoimmune thyroid disease (AITD) pathogenesis may result from a loss of immune tolerance to thyroid antigens. Regulatory T cells (Tregs) control immune responses, prevent excessive inflammation, and may be dysfunctional in AITD. We investigated the role of Tregs in Hashimoto's thyroiditis (HT) and Graves' disease (GD), complicated by Down syndrome (DS). Our goal was to identify differences in CD4(+)CD25(high) Treg function or number in patients with GD and HT, compared to healthy controls (HC). Treg number was assessed by flow cytometric analysis in samples from 20 AITD patients (seven GD, 13 HT), nine HC, and seven individuals with DS, a genetic disorder associated with multiple autoimmune disorders including AITD. Treg function was assessed by the inhibition of proliferation (radioactive thymidine incorporation into DNA) of blood-derived T effector (Teff) cells by Tregs in a coculture. Various methods of stimulation were contrasted. Cytokine levels were determined in conditioned media from the co-cultures. No differences were found in the frequency of Tregs as a percentage of CD4(+) cells between AITD and HC. AITD Tregs were less capable of inhibiting the proliferation of Teff cells when compared to HC; however, the impairment was dependent on the type of stimulation used. DS patients without AITD exhibited normal Treg function. We observed few differences in cytokine production between HC and AITD patients. Tregs from AITD patients are partly dysfunctional, possibly explaining their autoimmunity. Future work will elucidate the diagnostic potential and pathophysiology of Tregs in AITD.

CD4+CD25+ Regulatory T Cells Attenuate Lipopolysaccharide-Induced Systemic Inflammatory Responses and Promotes Survival in Murine Escherichia coli Infection

It is well established that CD4CD25 regulatory T cells (Tregs) downregulate inflammatory immune responses and help to maintain immune homeostasis. Recent reports have shown that ligation of germline encoded pattern recognition receptors such as Toll-like receptors can stimulate Tregs and therefore implicate Tregs in the pathophysiology of sepsis and other inflammatory diseases. In this report, we show that injection of lipopolysaccharide (LPS) leads to expansion of CD4CD25FoxP3 Tregs, suggesting that these cells may play an important role in immune regulation in LPS-induced acute inflammation. Indeed, genetic or immunological inhibition of Treg function using mice lacking functional Tregs (CD25 KO mice) or anti-CD25 monoclonal antibody (anti-CD25 mAb), respectively, led to acute death in an otherwise nonlethal LPS challenge. This was accompanied by exaggerated production of proinflammatory cytokines. Strikingly, adoptive transfer of CD4CD25 Tregs to CD25 KO mice before LPS challenge rescues mice from death. Unlike LPS, depletion of Tregs followed by concanavalin A (Con A) challenge does not result in mortality, suggesting that Treg depletion does not globally influence all models of acute inflammation. We authenticate our findings by showing that depletion of Tregs leads to mortality in a nonlethal Escherichia coli challenge accompanied by elevated serum levels of proinflammatory cytokines. Collectively, our results indicate that in addition to regulation of LPS-induced acute inflammation, Tregs help to improve bacterial clearance and promote survival in an acute model of bacterial infection.

Urinary Trypsin Inhibitor Attenuated Inflammatory Response of Patients Undergoing Cardiopulmonary Bypass by Inducing Activated Treg Cells

The urinary trypsin inhibitor (ulinastatin) is used in the clinic to prevent inflammatory responses in patients undergoing cardiopulmonary bypass (CPB); however, the anti-inflammatory mechanism is unclear. In the current study, we recruited 40 patients undergoing selective cardiac valve replacement surgery; and these patients were randomly divided into two groups (ulinastatin group [UG] and control group [CG]). We collected peripheral blood preoperatively, at the end of CPB, and postoperative days 1 and 3 and analyzed the kinetic changes in regulatory T (Treg) cell subsets. There was no statistically significant difference in the number of CD4(+) T cells between the two groups. The number of CD4(+)CD25(+) Treg cells, especially the suppressive activated Treg (aTreg) subset, was higher in the UG than the CG 1 and 3 days postoperatively. Thus, ulinastatin alleviated the inflammatory response during CPB by inducing the expansion of aTreg cells.

Characterization of a new regulatory CD4+ T cell subset in primary Sjogren's syndrome

CD4(+)CD25(low)GITR(+) T lymphocytes expressing FoxP3 and showing regulatory function have been recently described in healthy donors (HD). The objective of the study was to investigate their presence and role in patients with primary SS (pSS). CD4(+)CD25(low)GITR(+) cells circulating in peripheral blood (PB) of patients with pSS were isolated by MACS technique, their phenotype was studied by flow cytometry and real-time PCR, and their function was studied by in vitro co-culture. CD4(+)CD25(low)GITR(+) cells infiltrating salivary glands (SGs) were revealed by immunohistochemistry. Results indicated that conventional CD4(+)CD25(high) regulatory T cells (Tregs) are decreased, whereas CD4(+)CD25(low)GITR(+) cells are expanded in the PB of pSS as compared with HD. Phenotypic analysis demonstrated that CD4(+)CD25(low)GITR(+) cells display Treg markers, including FoxP3, TGF-β and IL-10, and functional experiments demonstrated that they exert a strong inhibitory activity against autologous effector cells. CD4(+)CD25(low)GITR(+) cells were detectable in great number in the SG inflammatory infiltrate. Interestingly, PB CD4(+)CD25(low)GITR(+) cell expansion was evident only in patients with inactive disease, while conventional CD4(+)CD25(high) Treg number was not associated with disease activity. The present data demonstrate that circulating CD4(+) cells expressing GITR, but with low levels of CD25 (CD4(+)CD25(low)GITR(+)), are detectable in pSS patients. These cells, displaying Treg phenotype and function, are present in SG inflamed tissues and are expanded in the PB of subjects with inactive disease. Data suggest that the expansion of CD4(+)CD25(low)GITR(+) cells in pSS may represent a counter-regulatory attempt against autoimmune-driven inflammation and may provide a new target for future treatment strategies.

Transient depletion of CD4+ CD25+ regulatory T cells results in multiple autoimmune diseases in wild‐type and B‐cell‐deficient NOD mice

Approximately 80% of female wild-type non-obese diabetic (WT NOD) mice spontaneously develop diabetes, whereas B-cell-deficient (B(-/-)) NOD mice are resistant to diabetes. B(-/-) mice are also resistant to other spontaneous and experimentally induced autoimmune diseases, including arthritis, systemic lupus erythematosus, Sjögren syndrome and thyroiditis. Under normal conditions, activation of self-reactive T cells in the periphery is limited by CD4(+) CD25(+) natural regulatory T (Treg) cells. B(-/-) NOD.H-2h4 mice, normally resistant to spontaneous autoimmune thyroiditis (SAT), develop SAT when Treg cells are depleted, suggesting that Treg cells are preferentially activated when autoantigen is initially presented by non-B-cell antigen-presenting cells. To test the hypothesis that increased Treg cell activity in B(-/-) mice contributes to their resistance to other autoimmune diseases, WT and B(-/-) NOD mice were given anti-CD25 to transiently deplete CD4(+) CD25(+) Treg cells. The WT and B(-/-) NOD mice given anti-CD25 developed diabetes much earlier than WT mice given rat IgG, whereas rat IgG-treated B(-/-) mice did not develop diabetes. Treg-cell-depleted mice had increased lymphocyte infiltration of the pancreas, salivary glands and thyroid compared with controls given rat IgG. These results are consistent with the hypothesis that resistance of B-cell-deficient NOD mice to several autoimmune diseases is due to the activity of Treg cells.

An Anti-Human CD13 Monoclonal Antibody That Suppresses the Suppressive Function of Treg Cells

CD13 (CD13/aminopeptidase N, APN, or CD13/APN) is a widely expressed type II membrane-bound metalloprotease. It is often overexpressed on cancer cells and expressed on CD4(+)CD25(hi) Treg cell subpopulation with higher suppressive ability. It has been determined to be a promising target in cancer diagnosis and therapy. In this study, a functional anti-human CD13 monoclonal antibody, MAb 9E4, was obtained and the specificity of this MAb was verified by flow cytometry. This MAb effectively recognized the CD13 molecule expressed on a series of malignant cell lines. Furthermore, we demonstrated that MAb 9E4 suppresses the suppressive function of Treg cells. This functional anti-human CD13 MAb provides a valuable tool for further study targeting the CD13 positive Treg cells.

Chronic exposure to stress predisposes to higher autoimmune susceptibility in C57BL/6 mice: Glucocorticoids as a double‐edged sword

Stress activates the hypothalamic-pituitary-adrenocortical axis to promote the release of corticosterone (CORT), which consequently suppresses pathogenic stimulation of the immune system. Paradoxically, however, stress often promotes autoimmunity through yet unknown mechanisms. Here we investigated how chronic variable stress (CVS), and the associated alterations in CORT levels, affect the susceptibility to experimental autoimmune encephalomyelitis (EAE) in female and male C57BL/6 mice. Under baseline (nonstressed) conditions, females exhibited substantially higher CORT levels and an attenuated EAE with less mortality than males. However, CVS induced a significantly worsened EAE in females, which was prevented if CORT signaling was blocked. In addition, females under CVS conditions showed a shift toward proinflammatory Th1/Th17 versus Th2 responses and a decreased proportion of CD4(+) CD25(+) Treg cells. This demonstrates that whereas C57BL/6 female mice generally exhibit higher CORT levels and an attenuated form of EAE than males, they become less responsive to the immunosuppressive effects of CORT under chronic stress and thereby prone to a higher risk of destructive autoimmunity.

Ribavirin Does Not Impair the Suppressive Activity of Foxp3+CD4+CD25+Regulatory T Cells

Ribavirin is an antiviral drug used in combination with pegylated interferon-α (IFN-α) for the treatment of hepatitis C virus (HCV) infection. Recently, ribavirin was reported to inhibit the suppressive activity of regulatory T (Treg) cells. In the present study, we re-evaluated the effect of ribavirin on Foxp3+CD4+CD25+ Treg cells from normal donors. First, we examined the expression of CTLA-4 and CD39, which are known to play a role in the suppressive function of Treg cells. We found that ribavirin treatment did not modulate the expression of CTLA-4 and CD39 in Treg cells. We also studied the effect of ribavirin on Treg cells in the presence of IFN-α; however, the expression of CTLA-4 and CD39 in Treg cells was not changed by ribavirin in the presence of IFN-α. Next, we directly evaluated the effect of ribavirin on the suppressive activity of Treg cells in the standard Treg suppression assay, by co-culturing CFSE-labeled non-Treg CD4+ T cells with purified Treg cells. We found that ribavirin did not attenuate the suppressive activity of Treg cells. Taken together, while ribavirin reversed Treg cell-mediated suppression of effector T cells in the previous study, we herein demonstrate that ribavirin does not impair the suppressive activity of Treg cells.

Functional changes in regulatory T cells during an experimental infection with sparganum (plerocercofid of Spirometra mansoni)

Regulatory T (Treg) cells are important in the regulation of immune response, but the exact regulation of Treg-cell function in vivo is still not well known. In the present study, we investigated the functional activity of CD4(+) CD25(+) Treg cells as well as the frequency and number of CD4(+) CD25(+) FoxP3(+) Treg cells in the spleens of experimentally infected mice with a tissue-migrating parasite, sparganum (plerocercoid of Spirometra mansoni) for 3 weeks. The results demonstrated fluctuations in the Treg-cell function during the parasite infection, being up-regulated at day 3, down-regulated until day 14, and thereafter up-regulated again at day 21. We also investigated the cytokine-producing capability of the splenocytes to study the pattern of immune response of the mice to the parasite. The results showed decreased capabilities of interleukin-2 (IL-2), interferon-γ (IFN-γ) and IL-17α production, whereas IL-4-producing and IL-10-producing capabilities were increased along with the parasitic infection. Meanwhile, IL-6-producing capability was increased to reach a peak at week 2, and thereafter was decreased to the baseline level. As a regulatory mechanism, we found that Treg-cell function was attenuated in the presence of the crude extracts of sparganum, but was enhanced in the presence of the excretory-secretory products, suggesting that sparganum products were involved in the triggering and regulation of immune response in the acute and chronic phases, respectively. Results show that Treg cells are central in the immune homeostasis in vivo that is maintained by host-parasite interactions during the parasitic infection.

The antiapoptotic activity of Heligmosomoides polygyrus antigen fractions

Our study identified Heligmosomoides polygyrus antigen factors with potential activity for regulation of T-cell proliferation and surviving of CD4(+) CD25(-) , CD4(+) CD25(hi) and CD3(+) CD8(+) cell populations. The antiapoptotic activity of antigenic fractions separated by HPLC was evaluated in vitro after exposure of cells to DEX and rTNF-α. Different populations of cells responded to antigen fractions in distinct pattern; the most sensitive population of cells to H. polygyrus products were CD4(+) CD25(hi) after exposure to DEX and CD3(+) CD8(+) T cells after exposure to rTNF-α. H. polygyrus antigens may influence survival of CD8(+) T cells by regulation of c-FLIP rather than Bcl-2, which affects survival of CD4(+) CD25(hi) Treg cells and CD4(+) T cells. Activation of NF-κB subunits, for example, p50 and p65 was essential for resistance of cells to apoptosis, and antigenic fractions F9 and F17 exerted different effect to F13. The most active fraction in inhibition of apoptosis was F9, which includes Hsp-60, calumenin, ferritin, galectin and thrombospondin. This study may provide new clues for recognition of factors that regulate the immune response during infection and which engage the TNF-α receptor-mediated and the mitochondria-mediated death pathway.