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Regulatory T cells (Tregs) and T helper 17 (Th17) cells contribute to cancer progression and prognosis. However, regulatory factors associated with Tregs-Th17 balance were not completely understood. We previously demonstrated an immune-modulatory capacity by Notch signaling inactivation to reverse Tregs-Th17 disequilibrium in chronic hepatitis C. Thus, the aim of current study was to assess the role of Notch signaling in modulation Tregs and Th17 cells function in gastric cancer (GC) patients. A total of 51 GC patients and 18 normal controls (NCs) were enrolled. Notch1 and Notch2 mRNA expressions were semiquantified by real-time polymerase chain reaction. Tregs/Th17 percentages, transcriptional factors, and cytokines production were investigated in response to the stimulation of Notch signaling inhibitor DAPT. Both Notch1 and Notch2 mRNA expressions were elevated in GC tissues and peripheral bloods in GC patients. CD4 + CD25 + CD127 dim/- Tregs and Th17 cells percentage was also elevated in GC patients compared with in NCs. DAPT treatment did not affect frequency of either circulating Tregs or Th17 cells, however, reduced FoxP3/RORγt mRNA expression and interleukin (IL)-35/IL-17 production in purified CD4 + T cells from GC patients. Moreover, blockade of Notch signaling also inhibited the suppressive function of purified CD4 + CD25 + CD127 dim/- Tregs from GC patients, which presented as elevation of cellular proliferation and IL-35 secretion. The current data further provided mechanism underlying Tregs-Th17 balance in GC patients. The link between Notch signaling and Th cells might lead to a new therapeutic target for GC patients., (© 2019 The Author(s).)

Background : Vitamin D has regulatory effects on different cells of the immune system and low levels are associated with several immune-mediated diseases. Aim : To investigate the association between neonatal 25-hydroxy vitamin D (25-OHD) level and the expression of lymphocyte activation markers (HLA-DR, CD69, CD25, CD45RA) on T-lymphocyte subpopulations and its impact in neonatal infection. Methods : 25-OHD level was measured in the cord blood of 56 neonates and their mothers using an enzyme immune-assay method. Based on the 25-OHD level, infants were categorised into four groups: severe deficiency ( n =  7), moderate deficiency ( n =  21), mild deficiency ( n =  15) and normal 25-OHD level ( n =  13). Mothers were classified into deficient ( n =  18), insufficient ( n =  21) and normal levels ( n =  17). T-lymphocyte subpopulations and lymphocyte activation markers were investigated using flow cytometry. Results : There was a positive correlation between maternal and cord blood 25-OHD levels ( r  = 0.503, p  = 0.001). The group with severe 25-OHD deficiency had the significantly lowest level of total lymphocytes, CD3+ T lymphocytes, CD4+ T-helper and CD8+ T-cytotoxic lymphocytes and CD4+CD45RA+ naïve T-cells compared with the other groups. The frequencies of CD8+CD25+, CD4+CD25+ and CD4+HLA-DR+ activated T-lymphocytes were significantly lower in the severe, moderate and mild deficiency groups than in the normal group. Seven of 43 (16.27%) infants with 25-OHD deficiency were admitted with sepsis to the neonatal intensive care unit and there were no cases of sepsis in the normal 25-OHD group. Conclusion : Vitamin D deficiency is associated with a reduction of lymphocyte subsets and altered T-lymphocyte activation which are considered to be risk factors for neonatal infection.

Immune responses play an important role in the pathogenesis of polycystic ovary syndrome (PCOS). However, the characteristics of T lymphocyte subsets in PCOS remain insufficiently understood. In this study, lymphocytes of follicular fluid (FF) were obtained from oocyte retrieval before in-vitro fertilization (IVF) in infertile women with or without PCOS. The levels of cluster of differentiation 25 (CD25), CD69, programmed death 1 (PD-1), interferon-γ (IFN-γ), interleukin 17A (IL-17A) and IL-10 in T lymphocytes were determined by flow cytometry. Our results showed that the percentage of FF CD8 + T cells was significantly decreased in infertile patients with PCOS (P < 0.05). Furthermore, the levels of CD69 and IFN-γ were significantly decreased and the level of PD-1 was increased in both CD4 + and CD8 + T cells from infertile patients with PCOS (P < 0.05). Moreover, the expression of PD-1 on CD4 + or CD8 + T cells was positively correlated with the estradiol (E2) levels in the serum and reversely correlated with the expression of IFN-γ in CD4 + or CD8 + T cells in infertile patients with PCOS. These results suggested that T cell dysfunction may be involved in the pathogenesis of PCOS.

Background: Regulatory T cells (Tregs) play a major role in tumor escape from immunosurveillance by suppressing effector cells. The number of Tregs is increased in tumor sites and peripheral blood of breast cancer patients. However, the data regarding phenotypic and functional heterogeneity of Treg subpopulations in breast cancer are limited. The present study aimed to investigate the number and suppressive potential of Tregs that possess natural naïve-(N nTregs), effector/memory-like (EM nTregs), and Tr1-like phenotypes in breast cancer patients and healthy women., Methods: The study included 10 HW and 17 primary breast cancer patients. Numbers of CD4 + CD25 + FoxP3 + CD45RA + N nTregs, CD4 + CD25 + FoxP3 + CD45RA - EM nTregs, and CD4 + IL-4 - IL-10 + Tr1 subsets and the expression of CTLA-4, CD39, GITR, LAP, and IL-35 by these Treg subsets were measured in freshly obtained peripheral blood by flow cytometry., Results: Herein, we demonstrate that the percentages of N nTregs, EM nTregs, CD25 + and FoxP3 + Tr1 cells are elevated in the peripheral blood of breast cancer patients, but do not correlate with cancer stages. Nevertheless, the frequency of CD25 + Tr1 cells was associated with nodal involvement, while the number of EM nTregs correlated with clinical outcome. The expression of CTLA-4 and IL-35 by all assessed Treg subsets was increased throughout all tumor stages (I-III)., Conclusions: Collectively, the current study shows phenotypic alterations in suppressive receptors of Treg subsets, suggesting that breast cancer patients have increased activity of N nTregs, EM nTregs and Tr1 cells; and EM nTregs and CD25 + Tr1 cells represent prospective markers for assessing disease prognosis.

The gut microbiota in chicken has long been studied, mostly from the perspective of growth performance. However, there are some immunological studies regarding gut homeostasis in chicken. Although CD4 + CD25 + T cells are reported to act as regulatory T cells (Tregs) in chicken, there have been no studies showing the relationship between gut microbiota and Tregs. Therefore, we established a model for 'antibiotics (ABX)-treated chickens' through administration of an antibiotic cocktail consisting of ampicillin, gentamycin, neomycin, metronidazole, and vancomycin in water for 7 days. CD4 + CD8 - CD25 + and CD4 + CD8 + CD25 + T cells in cecal tonsils were significantly decreased in this model. Gram-positive bacteria, especially Clostridia, was responsible for the changes in CD4 + CD8 - CD25 + or CD4 + CD8 + CD25 + T cells in cecal tonsils. Feeding ABX-treated chickens with acetate recovered CD4 + CD8 - CD25 + and CD4 + CD8 + CD25 + T cells in cecal tonsils. GPR43, a receptor for acetate, was highly expressed in CD4 + CD8 - CD25 + T cells. In conclusion, our study demonstrated that the gut microbiota can regulate the population of CD4 + CD8 - CD25 + and CD4 + CD8 + CD25 + T cells, and that acetate is responsible for the induction of CD4 + CD8 - CD25 + T cells in cecal tonsils via GPR43.

Previous studies established that GM-CSF-deficient (Csf2-deficient) mice exhibit profound resistance to experimental autoimmune encephalomyelitis. This study addressed whether the resistance of Csf2-deficient mice was a result of a requirement for GM-CSF in controlling the functional balance between effector and regulatory T cell subsets during experimental autoimmune encephalomyelitis. The main observation was that treatment with the anti-CD25 mAb PC61 rendered Csf2-deficient mice fully susceptible to severe, chronic experimental autoimmune encephalomyelitis, with disease incidences and severities equivalent to that of C57BL/6 mice. When both donors and recipients were treated with PC61 in a passive model of experimental autoimmune encephalomyelitis, adoptive transfer of myelin-specific Csf2-deficient T cells into Csf2-deficient recipients resulted in a nonresolving chronic course of severe paralytic experimental autoimmune encephalomyelitis. The peripheral Csf2-deficient T cell repertoire was marked by elevated CD3 + T cell frequencies that reflected substantial accumulations of naïve CD44 null-low CD4 + and CD8 + T cells but essentially normal frequencies of CD4 + CD25 + forkhead box P3 + T cells among the CD3 + T cell pool. These findings suggested that Csf2-deficient mice had secondary deficiencies in peripheral T cell sensitization to environmental antigens. In accordance, myelin oligodendrocyte glycoprotein 35-55/CFA-sensitized Csf2-deficient mice exhibited deficient peripheral sensitization to myelin oligodendrocyte glycoprotein, whereas pretreatment of Csf2-deficient mice with PC61 enabled the robust induction of myelin oligodendrocyte glycoprotein-specific T cell responses in the draining lymphatics. In conclusion, the experimental autoimmune encephalomyelitis resistance of Csf2-deficient mice, at least in part, reflects a deficient induction of effector T cell function that cannot surmount normal regulatory T cell barriers. Experimental autoimmune encephalomyelitis effector responses, however, are unleashed upon depletion of regulatory CD25 + T cells., (© Society for Leukocyte Biology.)

Unlabelled: Interleukin 2 (IL-2) signaling through the IL-2 receptor alpha chain (CD25) facilitates HIV replication in vitro and facilitates homeostatic proliferation of CD25(+) FoxP3(+) CD4(+) T cells. CD25(+) FoxP3(+) CD4(+) T cells may therefore constitute a suitable subset for HIV infection and plasma virion production. CD25(+) FoxP3(+) CD4(+) T cell frequencies, absolute numbers, and the expression of CCR5 and cell cycle marker Ki67 were studied in peripheral blood from HIV(+) and HIV(-) study volunteers. Different memory CD4(+) T cell subsets were then sorted for quantification of cell-associated HIV DNA and phylogenetic analyses of the highly variable EnvV1V3 region in comparison to plasma-derived virus sequences. In HIV(+) subjects, 51% (median) of CD25(+) FoxP3(+) CD4(+) T cells expressed the HIV coreceptor CCR5. Very high frequencies of Ki67(+) cells were detected in CD25(+) FoxP3(+) memory CD4(+) T cells (median, 27.6%) in comparison to CD25(-) FoxP3(-) memory CD4(+) T cells (median, 4.1%; P < 0.0001). HIV DNA content was 15-fold higher in CD25(+) FoxP3(+) memory CD4(+) T cells than in CD25(-) FoxP3(-) T cells (P = 0.003). EnvV1V3 sequences derived from CD25(+) FoxP3(+) memory CD4(+) T cells did not preferentially cluster with plasma-derived sequences. Quasi-identical cell-plasma sequence pairs were rare, and their proportion decreased with the estimated HIV infection duration. These data suggest that specific cellular characteristics of CD25(+) FoxP3(+) memory CD4(+) T cells might facilitate efficient HIV infection in vivo and passage of HIV DNA to cell progeny in the absence of active viral replication. The contribution of this cell population to plasma virion production remains unclear., Importance: Despite recent advances in the understanding of AIDS virus pathogenesis, which cell subsets support HIV infection and replication in vivo is incompletely understood. In vitro, the IL-2 signaling pathway and IL-2-dependent cell cycle induction are essential for HIV infection of stimulated T cells. CD25(+) FoxP3(+) memory CD4 T cells, often referred to as regulatory CD4 T cells, depend on IL-2 signaling for homeostatic proliferation in vivo Our results show that CD25(+) FoxP3(+) memory CD4(+) T cells often express the HIV coreceptor CCR5, are significantly more proliferative, and contain more HIV DNA than CD25(-) FoxP3(-) memory CD4 T cell subsets. The specific cellular characteristics of CD25(+) FoxP3(+) memory CD4(+) T cells probably facilitate efficient HIV infection in vivo and passage of HIV DNA to cell progeny in the absence of active viral replication. However, the contribution of this cell subset to plasma viremia remains unclear., (Copyright © 2016, American Society for Microbiology. All Rights Reserved.)

Cell-mediated immunity (CMI) plays a critical role in the control of brucellosis. Regulatory T cells (Tregs) have a functional character in modulating the balance between host immune response and tolerance, which can eventually lead to chronic infection or relapse. The aim of this study was to assess the alteration of Tregs in cases of brucellosis before and after treatment. Thirty cases of acute brucellosis with the mean age of 41.03±15.15 years (case group) and 30 healthy persons with the mean age of 40.63±13.95 years (control group) were selected and assessed. Peripheral blood mononuclear cells (PBMCs) were isolated from peripheral blood of all individuals. We analyzed the alteration of Treg cell count using flow cytometry for CD4, CD25, and FoxP3 markers. The level of CD4+ CD25+ FoxP3+ Treg cells was increased in active patients compared with controls (2.5±0.99% vs 1.6±0.84%, p= 0.0004), but it had declined in the treated cases (1.83±0.73%, p=0.02). The level of Tregs was elevated in three relapsed cases. The frequency of Tregs and Treg/Teff (effector T cell) ratio was correlated with inverse serum agglutination test (SAT) and, 2-mercaptoethanol (2-ME) titers as markers of treatment in brucellosis. Based on our findings, we suggest that regulatory cells, such as CD4+ CD25+ FoxP3+ Treg cells, may contribute to the development of infection processes involving immune responses in brucellosis, and evaluation of regulatory T-cell levels may be a potential diagnostic strategy for the treatment outcome in chronic and relapsed cases of brucellosis.

Background: The pro-inflammatory S100 calcium binding protein A8 (S100A8) is elevated in the serum of patients with Plasmodium falciparum malaria, but its function in Plasmodium vivax malaria is not yet clear. This function was investigated in P. vivax-infected patients in this study., Methods: The level of S100A8 in the serum was measured with ELISA. Full amino acids of S100A8 were synthesized to verify the functions for maturation of immature dendritic cell (iDC) and evaluation of CD4(+)CD25(+)Foxp3(+) regulatory T (Treg) generation by mature DC (mDC)., Results: A higher amount of S100A8 was detected in vivax-infected patients (141.2 ± 61.849 ng/ml, n = 40) compared with normal control group (48.1 ± 27.384 ng/ml, n = 40). The level of S100A8 did not coincide with that of anti-malarial antibody measured by indirect fluorescent antibody test (IFAT) using parasite-infected red blood cells as antigen. Programmed death-ligand 1 (PD-L1) was up-regulated on the surface of iDCs following treatment with synthetic S100A8, not with synthetic MSP-1, AMA-1 and CSP, as compared to the expression seen for non-treated iDCs. The addition of red blood cells of infected patients to iDCs also elevated their surface expression of CD86. However, the serum levels of S100A8 decreased with increase in parasitaemia. DCs matured by sera containing S100A8 generated Treg cells from naïve T cells. The ratio of Treg cells generated was inversely proportional to the concentration of S100A8 in sera., Conclusions: Treg cells suppress the activity of cytotoxic T cells, which kill malaria parasites; therefore, the up-regulation of S100A8 in malaria patients may contribute to pathogen immune escape or tolerance.

HCV is a global health problem with an estimated 230 million chronically infected people worldwide. It has been reported that a 17-kd protein translated from core-encoding genomic region can contribute to immune-mediated mechanisms associated with the development of the chronic disease. Also, Treg cells can be contributed to an inadequate response against the viruses, leading to chronic infection. Here we evaluated the ability of protein F to modulate the frequency of CD4+CD25+FoxP3+T and IL-10+T cells in patients with chronic HCV infection. F gene was amplified and cloned in the expression vector. The protein was purified and used for stimulation of PBMCs in the HCV chronic patients and the control groups. The frequency of CD4+CD25+FoxP3+ T cell-like populations and IL-10-producing CD4+CD25+ T cells was assessed in the HCV-infected patients and in the healthy controls by flow cytometry, which showed an increase of both CD4+CD25+FoxP3+ T cell-like population and IL-10-producing CD4+CD25+ T cells in the HCV-infected patients positive for anti-F antibody. Our results suggest the potential involvement of F and core antigens in increasing the frequency of CD4+CD25+FoxP3+ T cell-like population and IL-10-producing CD4+CD25+ T cells which may be associated with HCV-persistent infection., (© FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: The roles of CD4(+)CD25(+) regulatory T cells (Treg) in chronicity of hepatitis B virus (HBV) infection have been confirmed. We aimed to explore alteration of Treg in patients with HBV-related acute-on-chronic liver failure (ACLF)., Methods: Thirty-two HBV-related ACLF patients, 44 chronic hepatitis B patients, and 41 healthy controls were recruited. We detected frequencies of peripheral Treg and intrahepatic forkhead winged helix transcription factor (Foxp3)(+) cells. Inhibitory activity of Treg was assessed by functional suppression assays. Serum interferon-γ and interleukin-10 were also determined., Results: Peripheral Treg and intrahepatic Foxp3(+) cells were more markedly increased in ACLF than chronic hepatitis B and controls (all p < 0.001), and the Foxp3(+) cells located predominantly in the portal areas. The Treg frequency was positively correlated with HBV DNA load, international normalized ratio, model of end stage liver disease score, and serum interleukin-10 level in ACLF patients. Functional assays in vitro demonstrated that ACLF patients exhibited higher suppressive effects of Treg on proliferations of autologous CD4(+)CD25(-) T cells than controls. On logistic regression, prolonged international normalized ratio and higher peripheral Treg frequency predicted 30-day survival of ACLF., Conclusion: The patients with HBV-related ACLF exhibit increased amounts of Treg, of which redistribution from periphery to liver seems to modulate liver inflammation. Higher Treg amounts are associated with more severe liver disease in ACLF, and its level in combination with international normalized ratio may assist prediction of short-term outcomes of HBV-related ACLF., (Copyright © 2013. Published by Elsevier B.V.)

In the current study, we investigate changes in CD4+CD25+ cells in chickens during infectious bursal disease virus (IBDV) infection. The percentage of CD4+CD25+ cells in lymph organs, e.g., the thymus, spleen, bursa of Fabricius and peripheral blood, during the first 1-5 days post infection (dpi) was assessed by flow cytometry. The data revealed a remarkable decrease in the percentage of CD4+CD25+ cells in the thymus from 1 to 5 dpi and in the spleen during early infection. An increase of the percentage of CD4+CD25+ cells among peripheral blood lymphocytes was observed during the first two days of IBDV infection. Additionally, CD4+CD25+ cells infiltrated the bursa along with CD4+ cells after IBDV infection. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to measure the mRNA levels of immune-related cytokines in IBDV-infected thymus and bursa of Fabricius tissues. The data revealed that IBDV caused a significant increase in interleukin (IL)-10 mRNA levels, with the Harbin-1 strain (vvIBDV) inducing higher IL-10 expression than the Ts strain. Taken together, our data suggest that chicken CD4+CD25+ cells may participate in IBDV pathogenicity by migrating from their sites of origin and storage, the thymus and spleen, to the virally targeted bursa of Fabricius during IBDV infection.

CD4(+)CD25(+)FOXP3(+) regulatory T cells have long been shown to mediate susceptibility to Leishmania infection, mainly via interleukin 10 production. In this work, we showed that the main sources of interleukin 10 in peripheral blood mononuclear cells (PBMCs) from patients with cutaneous leishmaniasis due to Leishmania braziliensis are CD4(+)CD25(-)CD127(-/low)FOXP3(-) cells. Compared with uninfected controls, patients with CL had increased frequencies of circulating interleukin 10-producing CD4(+)CD25(-)CD127(-/low) cells, which efficiently suppressed tumor necrosis factor α production by the total PBMC population. Also, in CL lesions, interleukin 10 was mainly produced by CD4(+)CD25(-) cells, and interleukin 10 messenger RNA expression was associated with interleukin 27, interleukin 21, and interferon γ expression, rather than with FOXP3 or transforming growth factor β expressions. Active production of both interleukin 27 and interleukin 21, together with production of interferon γ and interleukin 10, was also detected in the lesions. Since these cytokines are associated with the differentiation and activity of Tr-1 cells, our results suggest that this cell population may play an important role in the immunomodulation of CL. Therefore, development of treatments that interfere with this pathway may lead to faster parasite elimination., (© The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)

Background: Conventional regulatory T cells (Tregs) can suppress human immunodeficiency virus type 1 (HIV-1)-specific immune responses but cannot control immune activation in primary HIV infection. Here, we characterized Treg subsets, using recently defined phenotypic delineation, and analyzed the relative contribution of cell subsets to the production of immunosuppressive cytokines in primary HIV infection., Methods: In a longitudinal prospective study, ex vivo phenotyping of fresh peripheral blood mononuclear cells from patients with primary HIV infection was performed at baseline and month 6 of follow-up to characterize Treg subsets, immune activation, and cytokine production in isolated CD4(+) T cells., Results: The frequency of CD4(+)CD25(+)CD127(low) Tregs and the distribution between the naive, memory, and activated/memory Treg subsets was similar in patients and healthy donors. However, Tregs from patients with primary HIV infection showed peculiar phenotypic profiles, such as elevated FoxP3, ICOS, and CTLA-4 expression, with CTLA-4 expression strikingly increased in all Treg subsets both at baseline and month 6 of follow-up. The great majority of interleukin 10 (IL-10)-producing CD4(+) T cells were FoxP3(neg) (ie, Tr1-like cells). In contrast to conventional Tregs, Tr1-like cells were inversely correlated with immune activation and not associated with lower effector T-cell responses., Conclusion: FoxP3(neg) Tr1-like cells-major contributors to IL-10 production-may have a beneficial role by controlling immune activation in early HIV infection., (© The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)

Tuberculosis (TB) remains the world's leading cause of morbidity and mortality. Although Mycobacterium bovis bacillus Calmette-Guérin (BCG) is the only vaccine currently in use, its efficacy is highly variable. It has been suggested that early antigenic presentation is a pivotal event leading to a better immune response in TB vaccine models. To investigate this further, we compared in vitro cell-mediated immune responses in the context of early sensitization with TB (i.e. healthy adults vaccinated with BCG when they were young, HD; n = 25) to those in its absence (i.e., newborns with naïve immunity to TB, UV; n = 10) by challenging mononuclear cells with BCG Moreau. After 48 hours, CD4+ and CD8+ T cells were harvested from both groups and stained for PD-1/CD25/ FOXP3. In addition, supernatants were assayed for a broad range of cytokines using an array system. The HD group showed robust reactivity to Protein Purified Derivative and BCG while the naïve, UV group did not. Similarly, in terms of PD-1 expression and Treg cells (CD4+/CD25high(+)/FOXP3+), only the HD group showed higher levels in CD4 lymphocytes. Otherwise, only the UV group showed expression of CD25dim+ as an activation marker dependent on BCG infection. In terms of cytokines, the HD group showed higher levels of Th1 (IL-2/TNF-α/IFN-γ) and regulatory (IL-10) profiles, with monocytes, but not Tr1 cells, acting as the main source of IL-10. Taken together, our results highlight critical roles of early sensitization with TB in mounting cell-mediated immune responses.

Background: Tolerance to the early acquisition of Helicobacter pylori is suggested because of a biased ratio of regulatory to effector T cells in a mice model. This study investigated whether the CD4CD25 regulatory T (Treg) and CD4+CD25- effector T (Teff) cell responses after H. pylori exposure determine H. pylori susceptibility in children., Methods: Treg and Teff cells from peripheral blood mononuclear cells (PBMCs) of H. pylori-infected and non-infected children were incubated with H. pylori protein. The cytokine levels and fraction of FOXP3+ to T cells were measured. FOXP3 expression was assessed by Western blotting and immunohistochemistry of gastric biopsies from dyspeptic children., Results: The fraction of FOXP3+ to CD4+CD25 high cells in PBMCs, FOXP3-positive staining and translation level in gastric tissues were higher in H. pylori-infected children than in controls (P < 0.05). The translation levels of TGF-β1 in gastric tissues were higher in H. pylori-infected children than in controls (P < 0.05). After H. pylori challenge, H. pylori-infected children had a positive net-change in TGF-β1 from Treg cells, and a negative net-change of IFN-γ from Teff cells. Paradoxically, the non-infected controls had a negative net-change in TGF-β1 from Treg cells, and a positive net-change of IFN-γ from Teff cells., Conclusions: The host response of Treg cells with increases in FOXP3 and TGF-β1 combined with a reduction in IFN-γ by Teff cells may contribute to H. pylori susceptibility in children.

We aimed to verify whether CD4(+)/CD25(+) T cells suppress CD4(+) T cells and secrete Granzyme B (GZB) during acute and chronic hepatitis C (CHC) infection. We enrolled 50 subjects: 20 patients with CHC (Group A), 15 healthy individuals (Group B), 10 patients with acute hepatitis C later evolved to persistent infection (Group C) and five patients who resolved hepatitis C virus infection during acute phase (Group D). We analysed, on enrolled subjects CD4(+)/CD25(+) T cells and related GZB production as well as Annexin V activity. Patients from Groups A and C had higher frequency and function of peripheral Treg cells than healthy individuals. Groups A and C showed an increase in spot-forming colonies (SFCs) of GZB compared with Group B (P < 0.01, Mann-Whitney U-test). CD4(+)/CD25(+) T cells in Group D had a lower number of GZB SFCs compared with Groups A and C but higher number than Group B (P < 0.01 Mann-Whitney U-test). Annexin V production was higher in Groups A and C than B or D. Patients having acute and chronic hepatitis C have a higher Treg frequency and function in peripheral blood than healthy controls or those resolving the infection in acute phase secreting GZB, probably inducing apoptosis., (© 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.)

CD4(+) T cells expressing the immunotolerizing molecule HLA-G have been described as a unique human thymus-derived regulatory T (tTreg) cell subset involved in immunoregulation and parenchymal homeostasis during infectious and autoimmune inflammation. We compared properties and molecular characteristics of human CD4(+)HLA-G(+) with those of CD4(+)CD25(+)FoxP3-expressing tTreg cells using in vitro studies of T-cell receptor (TCR) signaling, single-cell electrophysiology, and functional in vivo studies. Both tTreg populations are characterized by alterations in proximal-signaling pathways on TCR stimulation and a hyperpolarization of the plasma membrane when compared to conventional CD4(+) T cells. However, both clearly differ in phenotype and pattern of secreted cytokines, which results in distinct mechanisms of suppression: While CD4(+)HLA-G(+) cells secrete high levels of inhibitory molecules (IL-10, soluble HLA-G, IL-35), CD4(+)CD25(+)FoxP3(+) cells express these molecules at significantly lower levels and seem to exert their function mainly in a contact-dependent manner via cyclic adenosine-monophosphate. Finally we demonstrate that human CD4(+)HLA-G(+) tTreg cells significantly ameliorated graft-versus-host disease in a humanized mouse model as a first proof of their in vivo relevance. Our data further characterize and establish CD4(+)HLA-G(+) cells as a potent human tTreg population that can modulate polyclonal adaptive immune responses in vivo and thus being a promising candidate for potential clinical applications in the future., (© FASEB.)

Infections of neonatal piglets with Cystoisospora suis are responsible for substantial economic losses in pig production. To investigate kinetics of T-cell populations, which are possibly involved in this infection, lymphocytes from blood, spleen, mesenteric lymph nodes and the jejunal mucosa of infected and noninfected piglets were investigated by flow cytometry and immunohistochemistry at five time points during the acute phase of primary infection. Additionally, mRNA expression levels of pattern recognition receptors and immunomodulatory cytokines in the jejunum were investigated. T-cell receptor-γδ(+) T cells were found to be increased in the gut mucosa 4 days after infection and were most likely involved in the primary local immune response. Five to eleven days later, cytotoxic T cells peaked in this location, which was preceded by an expansion of this lymphocyte population in the mesenteric lymph nodes. In intestines of infected piglets, mRNA expressions of TLR-2, NOD2 and TNF-α were significantly upregulated, suggesting an involvement in parasite recognition, immune response and possibly also in immunopathology. Taken together, this study identifies cellular and molecular players involved in the early immune responses against C. suis, but their precise role in the pathogenesis and control of this neonatal disease requires further investigation., (© 2014 John Wiley & Sons Ltd.)

Background/purpose(s): We investigated whether CD4(+)CD25(+)Foxp3(+) regulatory T cells (Tregs) are induced in patients suffering from early-stage septic shock and distinguish them from noninfectious patients with systemic inflammatory response., Methods: The study included 37 patients with early-stage septic shock, 15 patients with noninfectious systemic inflammatory response syndrome (SIRS), and 24 heath controls. We prospectively assayed the fraction of Tregs expressing high levels of CD25 and forkhead box P3 (Foxp3) as well as the plasma levels of interferon-γ (IFN-γ), interleukin-4 (IL-4), and soluble CD25 in all the subjects studied., Results: Compared with the control groups, the plasma levels of IFN-γ [66.10 (45.23-85.08) pg/mL vs. 20.97 (17.58-26.21) pg/mL, p < 0.001] and IL-4 [100.69 (77.41-127.68) pg/mL vs. 70.40 (64.14-80.15) pg/mL, p < 0.001] as well as the IFN-γ/IL-4 ratio [0.66 (0.62-0.67) vs. 0.30 (0.27-0.33), p < 0.001] were significantly elevated in the patients with early-stage septic shock, but there was no difference between patients with sepsis and patients with SIRS. We found that the proportion of CD4(+)CD25(+)Foxp3(+) T cells was significantly increased in the patients with early-stage septic shock [(66.82 ± 21.79%) vs. (51.79 ± 21.79%) vs. (56.45 ± 10.68%), p = 0.003] in comparison with the SIRS and control groups, which could be differentiated from the patients with SIRS. The plasma levels of soluble CD25 were also increased, and positively correlated with the proportion of Tregs in patients with early-stage septic shock (Spearman correlation coefficient = 0.390, p = 0.003)., Conclusion: Our findings indicate that the proportion of CD4(+)CD25(+)Foxp3(+) T cells could be an indicator for the early diagnosis of sepsis. This proportion can also facilitate the evaluation of the patient's immune status and guide suitable immunoregulatory therapy., (Copyright © 2012. Published by Elsevier B.V.)

Effector T cell responses rely on a phenotypically and functionally heterogeneous population of cells. Whether this diversity is programmed before clonal expansion or in later phases as a result of stochastic events or asymmetric cell division is not fully understood. In this study, we first took advantage of a sensitive in vitro assay to analyze the composition of single CD8(+) T cell progenies. Heterogeneity was predominantly observed between progenies of distinct clones, but could also be detected within individual progenies. Furthermore, by physically isolating daughter cells of the first T cell division, we showed that differences in paired daughter cell progenies contributed to intraclonal diversification. Finally, we developed an in vivo limiting dilution assay to compare individual T cell progenies following immunization. We provided evidence for simultaneous intraclonal and interclonal diversification in vivo. Our results support the idea that T cell diversification is a continuous process, initiated before clonal expansion and amplified during the first and subsequent cell divisions.

Lentivirus infection activates CD4(+) CD25(+) T regulatory (Treg) cells. Activation of Treg cells may be due to direct virus infection or chronic antigenic stimulation. Herein we demonstrate that in vitro feline immunodeficiency virus (FIV) infection, but not UV-inactivated virus, activates Treg cells as measured by immunosuppressive function and upregulation of GARP, FoxP3, and membrane-bound transforming growth factor β (TGF-β). These data demonstrate for the first time that AIDS lentiviruses infect and activate Treg cells, potentially contributing to immune dysfunction.

Aims: Common variable immunodeficiency (CVID) is a primary antibody immunodeficiency with approximately 20% of patients reporting additional autoimmune symptoms. The primary aim of this study was to compare the levels of activated and regulatory T cells (Treg cells) in CVID patients in an attempt to clarify their possible interactions leading to the generation of autoimmunity., Methods: Immunophenotyping of T cells was performed by flow cytometry using a whole blood approach. Surface expression of human leukocyte antigen HLA class II DR and intracellular levels of granzyme B in T cell subsets were assessed; Treg levels were measured using CD4 CD25, FOXp3 and CTLA-4., Results: CVID patients had higher levels of granzyme B and HLA-DR on CD8(+) T cells compared with control values (mean of 59% vs 30% and 45% vs 21%, respectively). Patients also had reduced levels of Treg cells compared with control values (con mean=3.24% vs pat=2.54%). Patients with autoimmunity (5/23) had a similar level of T cell activation markers to the rest of the patients but with lower Treg cells (mean of 1.1%) and reduced CD25 and CTLA-4 expression. Patients with autoimmunity had a higher ratio of activated to Treg cells compared with patients with no autoimmune symptoms., Conclusions: These results highlight that reduced levels of Treg cells were associated with elevated levels of activated T cells, suggesting that reduced Treg cells in these patients may have functional consequences in allowing exaggerated T cell responses.

HTLV-1 infection is associated with several inflammatory disorders, including the neurodegenerative condition HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). It is unclear why a minority of infected subjects develops HAM/TSP. CD4⁺ T cells are the main target of infection and play a pivotal role in regulating immunity to HTLV and are hypothesized to participate in the pathogenesis of HAM/TSP. The CD39 ectonucleotidase receptor is expressed on CD4⁺ T cells and based on co-expression with CD25, marks T cells with distinct regulatory (CD39⁺CD25⁺) and effector (CD39⁺CD25⁻) function. Here, we investigated the expression of CD39 on CD4⁺ T cells from a cohort of HAM/TSP patients, HTLV-1 asymptomatic carriers (AC), and matched uninfected controls. The frequency of CD39⁺ CD4⁺ T cells was increased in HTLV-1 infected patients, regardless of clinical status. More importantly, the proportion of the immunostimulatory CD39⁺CD25⁻ CD4⁺ T-cell subset was significantly elevated in HAM/TSP patients as compared to AC and phenotypically had lower levels of the immunoinhibitory receptor, PD-1. We saw no difference in the frequency of CD39⁺CD25⁺ regulatory (Treg) cells between AC and HAM/TSP patients. However, these cells transition from being anergic to displaying a polyfunctional cytokine response following HTLV-1 infection. CD39⁻CD25⁺ T cell subsets predominantly secreted the inflammatory cytokine IL-17. We found that HAM/TSP patients had significantly fewer numbers of IL-17 secreting CD4⁺ T cells compared to uninfected controls. Taken together, we show that the expression of CD39 is upregulated on CD4⁺ T cells HAM/TSP patients. This upregulation may play a role in the development of the proinflammatory milieu through pathways both distinct and separate among the different CD39 T cell subsets. CD39 upregulation may therefore serve as a surrogate diagnostic marker of progression and could potentially be a target for interventions to reduce the development of HAM/TSP.

Objectives: CD4+CD25high regulatory T cells (TREG) represent a suppressive T cell subset deeply involved in the modulation of immune responses and eventually in the prevention of autoimmunity. Growing evidence demonstrated that patients with autoimmune and inflammatory chronic diseases display an impairment of TREG cells or activated effector T cells unresponsive to TREG. Glucocorticoid-induced TNFR-related protein (GITR) is a widely accepted marker of murine TREG cells, but little is known in humans. Aim of the present study was to investigate the characteristics of different subsets of TREG cells in Sjögren's syndrome and the potential role of GITR as marker of human TREG cells., Methods: Fifteen patients with primary Sjogren's syndrome (SS) and 10 sex- and age-matched normal controls (NC) were enrolled. CD4+ T cells were magnetic sorted from peripheral blood by negative selection. Cell phenotype was analyzed through flow-cytometry using primary and secondary antibodies. Disease activity was assessed using the EULAR Sjögren's syndrome disease activity index (ESSDAI)., Results: Although the proportion of circulating CD25highGITRhigh subset was similar in SS patients and NC, an expansion of the CD25-GITRhigh cell population was observed in the peripheral blood of SS patients. Interestingly, this expansion was more relevant in patients with inactive rather than active disease., Conclusions: The number of CD4+CD25-GITRhigh cells is increased in SS as compared to NC. Moreover, the fact that the expansion of this cell subset is prevalently observed in patients with inactive disease suggests that these cells may play a role in counteracting inflammatory response.

Background: Strain-specific effects of probiotics in pro- or anti-inflammatory immune responses have been well recognized. Several proinflammatory Lactobacillus strains have been shown to act as adjuvants to enhance the immunogenicity of vaccines. However, dose effects of probiotics in modulating immune responses are not clearly understood. This study examined the dose effects of Lactobacillus acidophilus (LA) NCFM strain on T cell immune responses to rotavirus vaccination in a gnotobiotic (Gn) pig model., Methods: Frequencies of IFN-γ producing CD4+ and CD8+ T cell and IL-10 and TGF-β producing CD4+CD25+ and CD4+CD25- regulatory T (Treg) cell responses were determined in the intestinal and systemic lymphoid tissues of Gn pigs vaccinated with an oral human rotavirus vaccine in conjunction with low dose (5 feedings; up to 10(6) colony forming units [CFU]/dose) or high dose (14 feedings; up to 10(9)CFU/dose) or without LA feeding., Results: Low dose LA significantly promoted IFN-γ producing T cell responses and down-regulated Treg cell responses and their TGF-β and IL-10 productions in all the tissues compared to the high dose LA and control groups. To the contrary, high dose LA increased the frequencies of Treg cells in most of the tissues compared to the control groups. The dose effects of LA on IFN-γ producing T cell and CD4+CD25- Treg cell immune responses were similar in the intestinal and systemic lymphoid tissues and were independent from the vaccination., Conclusion: Thus the same probiotic strain in different doses can either promote or suppress IFN-γ producing T cell or Treg cell immune responses. These findings have significant implications in the use of probiotic lactobacilli as immunostimulatory versus immunoregulatory agents. Probiotics can be ineffective or even detrimental if not used at the optimal dosage for the appropriate purposes., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Extrapulmonary tuberculosis may be due to underlying immune compromise. Immunosuppressive regulatory T cells (Treg cells), and CD4(+) T lymphocytes in general, are important in the host immune response to Mycobacterium tuberculosis. We evaluated T lymphocytes from patients after recovery from extrapulmonary tuberculosis, which may reflect conditions before M. tuberculosis infection. A case-control study was conducted among HIV-uninfected adults with previously treated extrapulmonary tuberculosis and 3 sets of controls: (i) subjects with previously treated pulmonary tuberculosis, (ii) close tuberculosis contacts with M. tuberculosis infection, and (iii) close tuberculosis contacts with no infection. Monocyte-depleted peripheral blood mononuclear cells (PBMC-M) were stained for CD4(+) CD25(hi) CD127(low) FoxP3(+) cell (Treg cell) and T lymphocyte activation. Both characteristics were compared as continuous variables between groups with the Kruskal-Wallis test. There were 7 extrapulmonary tuberculosis cases, 18 pulmonary tuberculosis controls, 17 controls with M. tuberculosis infection, and 18 controls without M. tuberculosis infection. The median Treg cell proportion was highest among persons with previous extrapulmonary tuberculosis (1.23%) compared to subjects with pulmonary tuberculosis (0.56%), latent M. tuberculosis infection (0.14%), or no M. tuberculosis infection (0.20%) (P = 0.001). The median proportion of CD4(+) T lymphocytes that expressed the activation markers HLA-DR and CD38 was highest for CD4(+) T lymphocytes from persons with previous extrapulmonary tuberculosis (0.79%) compared to subjects with pulmonary tuberculosis (0.44%), latent M. tuberculosis infection (0.14%), or no M. tuberculosis infection (0.32%) (P = 0.005). Compared with controls, persons with previously treated extrapulmonary tuberculosis had the highest Treg cell frequency, but also the highest levels of CD4(+) T lymphocyte activation. Immune dysregulation may be a feature of individuals at risk for extrapulmonary tuberculosis.

FOXP3 is critical for the development and function of CD4(+)CD25(bright) natural regulatory T cells (nTreg). Individuals harboring mutations in FOXP3 develop immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome (IPEX). We describe a child diagnosed with IPEX who underwent a reduced intensity, T and B cell depleted, matched unrelated donor bone marrow transplant followed by clinical resolution. Using lineage-specific donor chimerism studies, we demonstrate that non-myeloablative HSCT resolves disease in the context of low level donor hematopoietic stem cell (HSC) engraftment. Despite low-levels of donor HSC, thymically-derived nTreg and to a lesser extent CD4(+) and CD8(+) T cells, exhibit a selective in vivo growth advantage for populations containing a functional FOXP3 gene. Moreover, nTreg from this patient show regulatory function directly ex vivo. These results have implications for improving clinical therapy for patients with IPEX and provide mechanistic insight into the in vivo development of human nTreg and unexpectedly, non-regulatory T cells., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Background and Aim: A new subset of Treg cells, CD4(+) CD69(+) CD25(-) T cells, has been identified in mice. Herein, we aimed to identify this subset of T cells and to evaluate its function in patients with hepatocellular carcinoma (HCC)., Methods: We detected CD4(+) CD69(+) CD25(-) T cells and its expression of CCR6 and transforming growth factor-β1 (TGF-β1) in peripheral blood of 91 HCC patients, 38 chronic hepatitis patients and 34 healthy donors by flow cytometry. CD4(+) CD69(+) CD25(-) T cells in HCC tissues were also analyzed., Results: CD4(+) CD69(+) CD25(-) T cells were significantly increased in peripheral blood of HCC patients compared with healthy persons and chronic hepatitis patients (8.74% ± 0.42% vs 4.55% ± 0.33% and 5.15% ± 0.36%, P < 0.0001). The percentage of peripheral CD4(+) CD69(+) CD25(-) T cells was significantly higher in HCC patients with Tumor Node Metastasis (TNM) stage III plus IV (P < 0.05). Patients with large tumor size and tumor vascular invasion were inclined to obtain high percentage of CD4(+) CD69(+) CD25(-) T cells (P < 0.05). The frequency of membrane-bound TGF-β1 positive cells in CD4(+) CD69(+) CD25(-) T cells from HCC patients was higher than that from the other two groups (P < 0.0001). A considerable proportion of CD4(+) CD69(+) CD25(-) T cells were present in HCC tissues, which has significant correlation with tumor size and TNM stage. Few CD4(+) CD69(+) CD25(-) T cells express CCR6 both in peripheral blood and tumor tissues from HCC patients., Conclusions: Increased CD4(+) CD69(+) CD25(-) T cells in HCC patients are significantly correlated with tumor size, vascular invasion and TNM stage. Thus, increased CD4(+) CD69(+) CD25(-) T cells exert a critical role in HCC progression and might be a clinically aggressive phenotype of HCC., (© 2011 Journal of Gastroenterology and Hepatology Foundation and Blackwell Publishing Asia Pty Ltd.)

Background: Regulatory T cells have been implicated in the pathogenesis of COPD by the increased expression of CD25 on helper T cells along with enhanced intracellular expression of FoxP3 and low/absent CD127 expression on the cell surface., Method: Regulatory T cells were investigated in BALF from nine COPD subjects and compared to fourteen smokers with normal lung function and nine never-smokers., Results: In smokers with normal lung function, the expression of CD25+CD4+ was increased, whereas the proportions of FoxP3+ and CD127+ were unchanged compared to never-smokers. Among CD4+ cells expressing high levels of CD25, the proportion of FoxP3+ cells was decreased and the percentage of CD127+ was increased in smokers with normal lung function. CD4+CD25+ cells with low/absent CD127 expression were increased in smokers with normal lung function, but not in COPD, when compared to never smokers., Conclusion: The reduction of FoxP3 expression in BALF from smokers with normal lung function indicates that the increase in CD25 expression is not associated with the expansion of regulatory T cells. Instead, the high CD127 and low FoxP3 expressions implicate a predominantly non-regulatory CD25+ helper T-cell population in smokers and stable COPD. Therefore, we suggest a smoking-induced expansion of predominantly activated airway helper T cells that seem to persist after COPD development.

Background: Both regulatory T cells (Tregs) and PD-1/PD-L1 pathway were critically involved in HCV viral persistence. However, the association between them was not well investigated. Herein, we aimed to investigate the distributional profiles of Tregs subsets and association between PD-1 expression on these subsets and development of HCV long-term persistence., Methods: CD45RA and CD27 were employed to separate peripheral Tregs as naïve/central memory/effector memory/effector subsets. The phenotypic characteristics and PD-1 expression of Tregs were studied by flow cytometry., Results: In the present study, the majority of Tregs was identified as central memory phenotype in chronic hepatitis C patients compared with nearly equal contribution of naïve and central memory subsets in healthy individuals. PD-1 expression was elevated in all CD4+ T cell subset in chronic HCV infected patients, including Tregs. Of note, higher level of PD-1 expression was found on TEM- and effector-Treg than naïve- and TCM-Tregs subsets. The ratio of TEM-Tregs/naive-Tregs and TEM-Tregs/TCM-Tregs regarding to PD-1 MFI were significantly lower in CHC patients compared to controls., Conclusions: Our study indicated that distinctive characteristics of PD-1 expression on Tregs in HCV infection suggests associated with impaired adaptive immunity as well as viral long-term persistence. The cross talk between Treg cells and PD-1 induced inhibition in chronic HCV infection deserved further exploration for HCV infection associated immune pathogenesis.

Background: Blood transfusion (BT) may elicit both harmful and beneficial immune responses against a subsequent organ graft. Immune parameters of a single, non leukocyte-depleted BT were investigated in two groups: non-human leukocyte antigen (HLA)-sensitized recipients with a one-HLA-DR matched donor (protocolled BT [PBT]) and females with previous exposure to HLA alloantigens through pregnancy (donor-specific transfusion [DST])., Methods: Thirty-five percent of DST recipients and 9.5% of PBT recipients developed HLA antibodies after BT.Phenotypic and functional analyses were performed in pre-BT, 2 weeks post-BT, and more than 10 weeks post-BT samples (PBT: n=10; DST: n=14)., Result: The number of donor-reactive interferon-γ-producing memory T cells increased 2 weeks post-BT, but only in the DST group, increased frequencies persisted beyond 10 weeks (P0.004). In the DST recipients, the proportion of natural killer cells (CD3(-)CD56(+)) significantly increased after BT (P=0.01), whereas in PBT recipients, the proportion of regulatoryT cells (CD4(+)CD25(+)Foxp3(+)CD127 low) significantly increased at 2 weeks post-BT (P=0.039). Microarray analysis confirmed increased activity of genes involved in function of natural killer cells,Tcells, and Bcells in DSTrecipients and increased expression of immune regulatory genes (galectin-1, Foxo3a, and follistatin-like 3) in PBT recipients. Galectin-1 expression by quantitative polymerase chain reaction was significantly enhanced in peripheral blood cells after PBT (P0.05)., Conclusion: Decreased immune effector mechanisms combined with an increased immune regulatory cell signature after HLA-DR-matched BT in nonsensitized patients is in line with clinical observations of improved outcome of a subsequent graft. Previous sensitization, however, may lead to HLA antibody formation and prolonged donor-specific memory T-cell reactivity after BT.

Nephrotoxicity limits the use of cisplatin, a widely used chemotherapeutic agent for treatment of various malignancies. Overall, CD4+ T cells mediate cisplatin-induced renal injury; however, the CD4+CD25+ regulatory T-cell subset (CD4+CD25+ Treg) has broad suppressive effects on many different cell types. In this study, we determined whether CD4+CD25+ Treg cells had protective effects against cisplatin-induced acute renal injury in nu/nu mice that lack mature T cells. In these mice, there was marked attenuation of the decreased survival, renal dysfunction and tubular injury, renal tumor necrosis factor-α, and interleukin-1β cytokine levels. Furthermore, renal macrophage accumulation was reduced in CD4+CD25+ Treg cell-adoptive transferred nu/nu mice compared with control mice. Infusion of CD4+CD25+Treg cells into wild-type Balb/c mice reduced serum blood urea nitrogen and creatinine levels equivalent to those in nu/nu mice and extended their survival time after cisplatin injection. In contrast, depletion of CD4+CD25+ Treg cells in wild-type mice exacerbated kidney injury after cisplatin administration. Transcription factor Foxp3-positive cells (Treg cells) were detected in the kidneys of nu/nu mice after cisplatin injection. Our results suggest that CD4+CD25+ Treg cells directly affect cisplatin nephrotoxicity and their modulation represents an additional treatment strategy.

Importance of the Field: Hepatic cirrhosis is a frequent consequence of chronic hepatitis infection (HBV and HCV) or alcohol abuse and the most common cause of hepatocellular carcinoma (HCC). Currently, liver transplantation remains the only effective therapeutic approach for cirrhosis-related HCC patients. The evolution of the pathology strongly depends on immunological mechanisms., Areas Covered in This Review: Despite the presence of specific T cells, viral chronic infection and continuous tumor growth suggest a failure of immune control. It appears that direct suppression of antiviral or antitumor effector cells by regulatory T cells plays a pivotal role in the impairment of immune response. Several types of regulatory T cells have been described, natural regulatory T cells (nTreg) and induced-type 1 regulatory T cells (Tr1) being the best characterized., What the Reader Will Gain: Currently, there is no evidence for a direct implication of regulatory T cells in the evolution of hepatitis, especially concerning chronic infection, cirrhosis late stage and HCC progress. However, recent studies show that regulatory T cells are implicated in the modulation of HBV- and HCV-associated immune response, thus, promoting HCC progress., Take Home Message: Therefore, nTreg and Tr1 cells seem to play an important role in the control of immune response leading to chronic hepatitis infection and progression of the pathology to cirrhosis and HCC.

Objectives: Regulatory T cells (T(REG)) represent a T cell subset able to modulate immune response by suppressing autoreactive T-lymphocytes. The evidence of a reduced number and an impaired function of this cell population in autoimmune/inflammatory chronic diseases led to the hypothesis of its involvement in the pathogenesis of these disorders. Glucocorticoid-induced TNFR-related protein (GITR) is a well known marker of murine T(REG) cells, but little is known in humans. The aim of this study was to investigate the characteristics of T(REG) cells in systemic lupus erythematosus (SLE) and the potential role of GITR as marker of human T(REG)., Methods: Nineteen SLE patients and 15 sex- and age-matched normal controls (NC) were enrolled. CD4(+) T cells were magnetic sorted from peripheral blood by negative selection. Cell phenotype was analyzed through flow-cytometry using primary and secondary antibodies and real time polymerase-chain reaction (PCR) using TaqMan probes., Results: The CD25(high)GITR(high) subset was significantly decreased in SLE patients with respect to NC (0.37±0.21% vs 0.72±0.19%; p<0.05). On the opposite, the CD25⁻GITR(high) cell population was expanded in the peripheral blood of SLE patients (3.5±2.25 vs 0.70±0.32%, p<0.01). Interestingly, FoxP3 at mRNA level was expressed in both CD25⁻GITR(high) and CD25(high)GITR(high) cells, suggesting that both cell subsets have regulatory activity., Conclusions: CD4(+)CD25⁻GITR(high) cells are increased in SLE as compared to NC. The expression of high level of GITR, but not CD25, on FoxP3+ cells appears to point to a regulatory phenotype of this peculiar T cell subset.

Lymphoid nodules are a normal component of the mucosa of the rectum, but little is known about their function and whether they contribute to the host immune response in malignancy. In rectal cancer specimens from patients with local (n=18), regional (n=12) and distant (n=10) disease, we quantified T cell (CD3, CD25) and dendritic cell (CD1a, CD83) levels at the tumour margin as well as within tumour-associated lymphoid nodules. In normal tissue CD3+, but not CD25+, T cells are concentrated at high levels within lymphoid nodules, with significantly fewer cells found in surrounding normal mucosa (P=0.001). Mature (CD83), but not immature (CD1a), dendritic cells in normal tissue are also found clustered almost exclusively within lymphoid nodules (P=<0.0001). In rectal tumours, both CD3+ T cells (P=0.004) and CD83+ dendritic cells (P=0.0001) are also localized preferentially within tumour-associated lymphoid nodules. However, when comparing tumour specimens to normal rectal tissue, the average density of CD3+ T cells (P=0.0005) and CD83+ dendritic cells (P=0.0006) in tumour-associated lymphoid nodules was significantly less than that seen in lymphoid nodules in normal mucosa. Interestingly, regardless of where quantified, T cell and dendritic cell levels did not depend upon the stage of disease. Increased CD3+ T cell infiltration of tumour-associated lymphoid nodules predicted improved survival, independent of stage (P=0.05). Other T cell (CD25) markers and different levels of CD1a+ or CD83+ dendritic cells did not predict survival. Tumour-associated lymphoid nodules, enriched in dendritic cells and T cells, may be an important site for antigen presentation and increased T cell infiltration may be a marker for improved survival.

Previously, we found that co-expression of CD25 and TNFR2 identified the most suppressive subset of mouse Treg. In this study, we report that human peripheral blood (PB) FOXP3(+) cells present in CD25(high), CD25(low) and even CD25(-) subsets of CD4(+) cells expressed high levels of TNFR2. Consequently, TNFR2-expressing CD4(+)CD25(+) Treg included all of the FOXP3(+) cells present in the CD4(+)CD25(high) subset as well as a substantial proportion of the FOXP3(+) cells present in the CD4(+)CD25(low) subset. Flow cytometric analysis of PB identified five-fold more Treg, determined by FOXP3 expression, in the CD4(+)CD25(+)TNFR2(+) subset than in the CD4(+)CD25(high) subset. In addition, similar levels of FOXP3(+) cells were identified in both the CD4(+)CD25(+)TNFR2(+) and CD4(+)CD25(+)CD127(low/-) subsets. Furthermore, the CD4(+)CD25(+)TNFR2(+) subset expressed high levels of CTLA-4, CD45RO, CCR4 and low levels of CD45RA and CD127, a phenotype characteristic of Treg. Upon TCR stimulation, human PB CD4(+)CD25(+)TNFR2(+) cells were anergic and markedly inhibited the proliferation and cytokine production of co-cultured T-responder cells. In contrast, CD4(+)CD25(+)TNFR2(-) and CD4(+)CD25(-)TNFR2(+) T cells did not show inhibitory activity. As some non-Treg express TNFR2, the combination of CD25 and TNFR2 must be used to identify a larger population of human Treg, a population that may prove to be of diagnostic and therapeutic benefit in cancer and autoimmune diseases.

Although T central memory cells have been described as the most effective T-cell subtype against tumor growth, little is known about the requirements needed for their optimal ex vivo generation. Hence, our goal is to establish a protocol that will lead to consistent ex vivo generation of lymphocytes skewed toward a central memory phenotype. Antigen-specific T-cell lines were generated by ex vivo stimulation with Class-I and Class-II melanoma peptide pulsed dendritic cells in the presence of either IL-2 or IL-15 plus IL-21. Tumor specific lymphocytes of both central memory and effector characteristics were consistently generated from healthy donors and melanoma patients. IL15/IL21 cultures result in a cell population with a lower proportion of CD4(+)CD25(high)FoxP3(+) regulatory cells and higher number of CD8(+) and CD56(+) cells, and consequently render a higher yield of cells with a greater cytolytic activity and IFN-gamma production against melanoma cell lines.

The vagus nerve is a conduit for bidirectional signaling between the brain and the viscera. Vagal signaling has been shown to downregulate gastrointestinal inflammation, and the mechanism is thought to involve acetylcholine binding to the alpha-7 subunit of the nicotinic acetylcholine receptor on macrophages. The aims of this study were to quantify the impact of vagotomy in vivo by visualizing nuclear factor (NF)-kappaB activity and to determine if the proinflammatory impact of vagotomy could be transferred by lymphocytes. Real-time biophotonic imaging revealed that subdiaphragmatic vagotomy resulted in increased levels of NF-kappaB in vivo. NF-kappaB activation was further exaggerated in vivo following exposure to 4% DSS for 5 days. Vagotomized animals also exhibited higher disease activity scores and secreted more proinflammatory cytokines. Adoptive transfer of CD4(+) T cells from vagotomized animals (but not CD4(+) T cells from sham-operated controls) to naive dextran sulfate sodium (DSS)-treated recipients resulted in increased inflammatory scores. Further examination of the CD4(+) T cells revealed that adoptive transfer of the CD25(-) population alone from vagotomized donors (but not sham-operated donors) was sufficient to aggravate colitis in DSS-treated recipients. Increased DSS-induced inflammation was associated with reduced CD4(+)CD25(+)Foxp3(+) regulatory T cell numbers in recipients. This study clearly demonstrates the ability of the vagus nerve to modulate activity of the proinflammatory transcription factor NF-kappaB in vivo. The proinflammatory effect of vagotomy is transferable using splenic T cells and highlights a previously unappreciated cellular mechanism for linking central parasympathetic processes with mucosal inflammation and immune homeostasis.

We recently reported a critical role for T cells in the induction of eosinophilic esophagitis (EE) in mice; however, the role of specific T cell subsets in disease pathogenesis is not yet understood. In the current study, we tested the hypothesis that allergen-induced EE develops in response to the disproportion of functionally different effector and regulatory T cells in the esophagus. Fluorescence-activated cell sorter analysis was performed to examine activated T cell subsets using the cell surface activation markers CD25 and CD69. A significant increase in activated CD4(+) and CD4(-) T cells was observed in the total esophageal cells isolated from the mouse model of EE. Furthermore, an imbalance in the effector and regulatory T cells was observed in the esophagus. The esophageal CD4(+)CD45RB(high) effector T cells in allergen-challenged mice increased compared with saline-challenged mice (65.4 +/- 3.6 x 10(3) to 44.8 +/- 4.2 x 10(3)), whereas CD4(+)CD45RB(low) mostly regulatory T cells decreased in allergen-challenged mice compared with saline-challenged mice (5.8 +/- 0.9 x 10(3) from 10.2 +/- 1.7 x 10(3)). The functional characteristics were examined by analysis of the pro- and anti-inflammatory cytokine profile of purified low and high CD4(+)CD45RB subsets from the spleen. Additionally, a significantly reduced interleukin (IL)-2 production by CD4(+)CD45RB(low) cells in allergen-challenged mice compared with saline-challenged mice was observed. The reduced IL-2 in the CD4(+)CD45RB(low) subset may be associated with reduction of CD4(+)CD45RB(low) subset. In conclusion, our results suggest that local regulatory interaction of CD45RB(high) and CD45RB(low) CD4(+) T cells may be required for protective and pathogenic immunity in EE.

Background: During extracorporeal photophoresis (ECP), peripheral blood mononuclear cells are treated with DNA-intercalating agents and irradiated with ultraviolet light. This procedure exerts immunosuppressive effects, most likely mediated by regulatory T cells (Treg). However, the underlying mechanisms are not clear yet. In our study, we investigated the effect of ECP on frequency and function of Treg in the peripheral blood of patients suffering from graft-versus-host disease., Methods: Whole blood samples from graft-versus-host disease patients were taken before and after the ECP treatment on 2 consecutive days. Phenotypical analysis of changes in distinct leukocyte subsets within the peripheral blood of patients and healthy controls was performed by means of flow cytometry. Functional analysis of the Treg population after magnetic bead isolation was performed using conventional suppression assays, and adenosine was detected by means of high pressure liquid chromatography and Lanzetta assays., Results: We show that the frequency of CD4/CD25/FoxP3 Treg in the peripheral blood increases after each cycle of ECP and also in the course of treatment. The suppressive capacity of Treg after ECP was increased compared with that of Treg before ECP, although not reaching the suppression levels obtained with Treg from healthy controls. Furthermore, we show that ECP stimulates the CD39-mediated production of adenosine by Treg, which substantially reduces the T-cell proliferation in in vitro suppression assays., Conclusion: Our data indicate that ECP stimulates the conversion of ATP to adenosine by the ectonucleotiodase CD39, which acts as a novel soluble immunosuppressive reagent mediating immunosuppression of Treg.

Cryopreservation of peripheral blood mononuclear cells (PBMC) is essential for many clinical and research assays. Some studies reported consistent changes in PBMC phenotype following cryopreservation. We hypothesized that PBMC freezing may have a negative impact on estimation of the frequency of T regulatory cell (Treg). Treg levels were measured in 6 fresh PBMC samples isolated from 6 healthy donors and these levels were re-measured after freezing for three weeks. Herein, we report a significant reduction in Treg frequency in all samples following cryopreservation.

Coxsackievirus B3 (CVB3) causes severe myocarditis in BALB/c mice which depends upon CD4(+) T helper type 1 [Th1; i.e. interferon-gamma(+) (IFN-gamma(+))] and gammadelta(+) cells. Depleting gammadelta(+) cells using anti-gammadelta antibody suppresses myocarditis and CD4(+) IFN-gamma(+) cell numbers in the spleen and heart of infected mice while increasing CD4(+) FoxP3(+) cells. Mice deficient in gammadelta(+) cells have increased numbers of naïve (CD44(lo) CD62L(hi)) and fewer effector (CD44(hi) CD62(lo)) memory CD4(+) cells than infected gammadelta(+)-cell-sufficient mice. Virus neutralizing antibody titres are not significantly different between gammadelta(+) T-cell-sufficient and -deficient animals. To confirm that the memory cell response differs in acutely infected mice lacking gammadelta(+) cells, CD4(+) cells were purified and adoptively transferred into naïve recipients, which were rested for 4 weeks then infected with CVB3. Recipients given either 0.5 x 10(6) or 1.0 x 10(6) CD4(+) from infected donors developed over twice the severity myocarditis and 10-fold less cardiac virus titre compared with recipients given equivalent numbers of CD4(+) cells from infected and gammadelta(+)-cell-depleted donor animals. Additionally, to show that more functionally active T regulatory cells are present in gammadelta(+) T-cell-depleted mice, CD4(+) CD25(+) and CD4(+) CD25(-) cells were isolated and adoptively transferred into infected recipients. Mice receiving CD4(+) CD25(+) cells from gammadelta(+) T-cell-depleted donors developed significantly less myocarditis and CD4(+) Th1 cell responses compared with mice receiving equal numbers of CD4(+) CD25(+) cells from infected gammadelta(+) T-cell-sufficient animals. This study shows that gammadelta(+) cells promote CD4(+) IFN-gamma(+) acute and memory responses by limiting FoxP3(+) T regulatory cell activation.

Vdelta2+ T cells, the major circulating T-cell receptor-gammadelta-positive (TCR-gammadelta+) T-cell subset in healthy adults, are involved in immunity against many microbial pathogens including Mycobacterium tuberculosis. Vdelta2+ T cells recognize small phosphorylated metabolites (phosphoantigens), expand in response to whole M. tuberculosis bacilli, and complement the protective functions of CD4+ T cells. CD4+ CD25(high) Foxp3+ T cells (Tregs) comprise 5-10% of circulating T cells and are increased in patients with active tuberculosis (TB). We investigated whether, in addition to their known role in suppressing TCR-alphabeta+ lymphocytes, Tregs suppress Vdelta2+ T-cell function. We found that depletion of Tregs from peripheral blood mononuclear cells increased Vdelta2+ T-cell expansion in response to M. tuberculosis (H37Ra) in tuberculin-skin-test-positive donors. We developed a suppression assay with fluorescence-activated cell sorting-purified Tregs and Vdelta2+ T cells by coincubating the two cell types at a 1 : 1 ratio. The Tregs partially suppressed interferon-gamma secretion by Vdelta2+ T cells in response to anti-CD3 monoclonal antibody plus interleukin-2 (IL-2). In addition, Tregs downregulated the Vdelta2+ T-cell interferon-gamma responses induced by phosphoantigen (BrHPP) and IL-2. Under the latter conditions there was no TCR stimulus for Tregs and therefore IL-2 probably triggered suppressor activity. Addition of purified protein derivative (PPD) increased the suppression of Vdelta2+ T cells, suggesting that PPD activated antigen-specific Tregs. Our study provides evidence that Tregs suppress both anti-CD3 and antigen-driven Vdelta2+ T-cell activation. Antigen-specific Tregs may therefore contribute to the Vdelta2+ T-cell functional deficiencies observed in TB.

Forkhead box P3 (FoxP3) is a transcription factor whose expression characterizes regulatory T cells (T(reg)), but it is also present on activated T cells, thus hindering correct T(reg) identification. Using classical markers for T(reg) recognition, discordant results were found in terms of T(reg) expansion during active tuberculosis (TB) disease. Recently CD39 has been shown to be an accurate marker for T(reg) detection. The objectives of this study were: (i) to identify T(reg) expressing CD39 in patients with TB and to compare the results with those obtained by the standard phenotypic markers; (ii) to evaluate if T(reg) are expanded in vitro by exogenous interleukin (IL)-2 or by antigen-specific stimulation; and (iii) to characterize T(reg) function on the modulation of antigen-specific responses. We enrolled 13 patients with pulmonary TB and 12 healthy controls. T(reg) were evaluated by flow cytometry ex vivo and after antigen-specific in vitro stimulation using CD25, FoxP3, CD127 and CD39 markers. Results indicate that CD39(+) cells within the CD4(+)CD25(high) cells have T(reg) properties (absence of interferon-gamma production and transforming growth factor-beta1 release upon stimulation). Ex vivo analysis did not show significant differences between TB patients and controls of T(reg) by classical or novel markers. In contrast, a significantly higher percentage of T(reg) was found in TB patients after antigen-specific stimulation both in the presence or absence of IL-2. Depletion of CD39(+) T(reg) increased RD1-specific responses significantly. In conclusion, CD39 is an appropriate marker for T(reg) identification in TB. These results can be useful for future studies to monitor Mycobacterium tuberculosis-specific response during TB.

Staphylococcal enterotoxin B (SEB) activates T cells via non-canonical signalling through the T cell receptor and is an established model for T cell unresponsiveness in vivo. In this study, we sought to characterize the suppressive qualities of SEB-exposed CD4(+) T cells and correlate this with genetic signatures of anergy and suppression. SEB-exposed CD25(+) and CD25(-)Vbeta8(+)CD4(+) T cells expressed forkhead box P3 (FoxP3) at levels comparable to naive CD25(+) T regulatory cells and were enriched after exposure in vivo. Gene related to anergy in lymphocytes (GRAIL), an anergy-related E3 ubiquitin ligase, was up-regulated in the SEB-exposed CD25(+) and CD25(-)FoxP3(+)Vbeta8(+)CD4(+) T cells and FoxP3(-)CD25(-)Vbeta8(+)CD4(+) T cells, suggesting that GRAIL may be important for dominant and recessive tolerance. The SEB-exposed FoxP3(+)GRAIL(+) T cells were highly suppressive and non-proliferative independent of CD25 expression level and via a glucocorticoid-induced tumour necrosis factor R-related protein-independent mechanism, whereas naive T regulatory cells were non-suppressive and partially proliferative with SEB activation in vitro. Lastly, adoptive transfer of conventional T cells revealed that induction of FoxP3(+) regulatory cells is not operational in this model system. These data provide a novel paradigm for chronic non-canonical T cell receptor engagement leading to highly suppressive FoxP3(+)GRAIL(+)CD4(+) T cells.

Cyclic AMP (cAMP) is a ubiquitous second messenger that regulates diverse cellular functions. It has been found that CD4(+)CD25(+) regulatory T (T(REG)) cells exert their suppressor function by transferring cAMP to responder T cells. Here, we show that miR-142-3p regulates the production of cAMP by targeting adenylyl cyclase (AC) 9 messenger RNA in CD4(+)CD25(-) T cells and CD4(+)CD25(+) T(REG) cells. miR-142-3p limits the level of cAMP in CD4(+)CD25(-) T cells by inhibiting AC9 production, whereas forkhead box P3 (FOXP3) downregulates miR-142-3p to keep the AC9/cAMP pathway active in CD4(+)CD25(+) T(REG) cells. These findings reveal a new molecular mechanism through which CD4(+)CD25(+) T(REG) cells contain a high level of cAMP for their suppressor function, and also suggest that the microRNA controlling AC expression might restrict the final level of cAMP in various types of cells.

Tumour growth promotes the expansion of CD4(+) CD25(+) FoxP3(+) regulatory T cells (Tregs) which suppress various arms of immune responses and might therefore contribute to tumour immunosurveillance. In this study, we found an inverse correlation between circulating Treg frequencies and phosphoantigen-induced gammadelta T-cell proliferation in cancer patients, which prompted us to address the role of Tregs in controlling the gammadelta T-cell arm of innate immune responses. In vitro, human Treg-peripheral blood mononuclear cell (PBMC) co-cultures strongly inhibited phosphoantigen-induced proliferation of gammadelta T cells and depletion of Tregs restored the impaired phosphoantigen-induced gammadelta T-cell proliferation of cancer patients. Tregs did not suppress other effector functions of gammadelta T cells such as cytokine production or cytotoxicity. Our experiments indicate that Tregs do not mediate their suppressive activity via a cell-cell contact-dependent mechanism, but rather secrete a soluble non-proteinaceous factor, which is independent of known soluble factors interacting with amino acid depletion (e.g. arginase-diminished arginine and indolamine 2,3-dioxygenase-diminished tryptophan) or nitric oxide (NO) production. However, the proliferative activity of alphabeta T cells was not affected by this cell-cell contact-independent suppressive activity induced by Tregs. In conclusion, these findings indicate a potential new mechanism by which Tregs can specifically suppress gammadelta T cells and highlight the strategy of combining Treg inhibition with subsequent gammadelta T-cell activation to enhance gammadelta T cell-mediated immunotherapy.