Accumulation Of Foxp3 Research Articles

Interleukin-7 matures suppressive CD127+ forkhead box P3 (FoxP3)+ T cells into CD127- CD25high FoxP3+ regulatory T cells

We have identified a novel interleukin (IL)-7-responsive T cell population [forkhead box P3 (FoxP3(+) ) CD4(+) CD25(+) CD127(+) ] that is comparably functionally suppressive to conventional FoxP3(+) CD4(+) CD25(+) regulatory T cells (T(regs) ). Although IL-2 is the most critical cytokine for thymic development of FoxP3(+) T(regs) , in the periphery other cytokines can be compensatory. CD25(+) CD127(+) T cells treated with IL-7 phenotypically 'matured' into the known 'classical' FoxP3(+) CD4(+) CD25(high) CD127(-) FoxP3(+) T(regs) . In freshly isolated splenocytes, the highest level of FoxP3 expression was found in CD127(+) CD25(+) T cells when compared with CD127(-) CD25(+) or CD127(+) CD25(-) cells. IL-7 treatment of CD4(+) CD25(+) T cells induced an increase in the accumulation of FoxP3 in the nucleus in vitro. IL-7-mediated CD25 cell surface up-regulation was accompanied by a concurrent down-regulation of CD127 in vitro. IL-7 treatment of the CD127(+) CD25(+) FoxP3(+) cells also resulted in up-regulation of cytotoxic T lymphocyte antigen 4 without any changes in CD45RA at the cell surface. Collectively, these data support emerging evidence that FoxP3(+) T cells expressing CD127 are comparably functionally suppressive to CD25(+) CD127(-) FoxP3(+) T cells. This IL-7-sensitive regulation of FoxP3(+) T(reg) phenotype could underlie one peripheral non-IL-2-dependent compensatory mechanism of T(reg) survival and functional activity, particularly for adaptive T(regs) in the control of autoimmunity or suppression of activated effector T cells.

Accumulation of Foxp3+ T Regulatory Cells in Draining Lymph Nodes Correlates with Disease Progression and Immune Suppression in Colorectal Cancer Patients

To assess the relation of Foxp3(+) regulatory T cells (Treg) in tumor draining lymph nodes (TDLNs) with tumor progression and immune suppression in colorectal cancer (CRC). Flow cytometry was used to analyze the densities of Tregs in lymphocytes of TDLNs, peripheral blood, and tumors from 34 patients with CRC. The frequency of Tregs was compared and evaluated for the association with disease stage. The effect of Tregs on the function of CD8(+) T cells was investigated by IFN-gamma production. The density of Foxp3(+) Tregs in TDLNs was dramatically higher than that in peripheral blood lymphocytes, but significantly lower than that in tumor-infiltrating lymphocytes. Importantly, the frequency of Foxp3(+) Tregs in TDLNs, rather than that in tumors and peripheral blood, was positively correlated with disease stage. In addition, the functions of CD8(+) T cells were impaired in TDLNs compared with peripheral blood lymphocytes and were restored after Treg depletion. Foxp3(+) Tregs in TDLNs are more correlated with disease progression and potentially influence CD8(+) T-cell functions. This study suggests that the frequency of Tregs in TDLNs may provide a valuable prognostic tool in the treatment of CRC.

Brief Definitive Report: Human visceral leishmaniasis is not associated with expansion or accumulation of Foxp3+ CD4 cells in blood or spleen

Natural regulatory T cells (CD4(+) CD25(+) Foxp3(+)), natural regulatory T cells (nTreg), play an important role in the regulation of inflammatory immune responses. However, the immunosuppressive properties of nTreg may unfavourably affect the host's ability to clear certain infections. In human visceral leishmaniasis (VL), reports on the frequency and function of nTreg are not conclusive. A limitation of our own previous studies that did not indicate a major role for Foxp3(+) nTreg in VL pathogenesis was that Foxp3 was measured by mRNA expression alone, as other tools were not available at the time. We have in this study assessed CD4(+)CD25(+)Foxp3(+) cells in splenic aspirates and peripheral blood mononuclear cells (PBMC) from an extensive series of patients with VL and endemic controls (EC) by flow cytometry (FACS). The results do not show increased frequencies of Foxp3(+) cells in patient with VL pre- and post-treatment, neither were they elevated when compared to PBMC of EC. We conclude that active VL is not associated with increased frequencies of peripheral Foxp3 Treg or accumulation at the site of infection.

Intracerebral Mycobacterium bovis bacilli Calmette–Guerin infection-induced immune responses in the CNS

To study whether cerebral mycobacterial infection induces granuloma and protective immunity similar to systemic infection, we intracerebrally infected mice with Mycobacterium bovis bacilli Calmette–Guerin. Granuloma and IFN-γ +CD4 + T cell responses are induced in the central nervous system (CNS) similar to periphery, but the presence of IFN-γIL-17 double-positive CD4 + T cells is unique to the CNS. The major CNS source of TNF-α is microglia, with modest production by CD4 + T cells and macrophage. Protective immunity is accompanied by accumulation of Foxp3 +CD4 + T cells and PD-L2 + dendritic cells, suggesting that both inflammatory and anti-inflammatory responses develop in the CNS following mycobacterial infection.

Distribution of Foxp3 + T-regulatory cells in experimental autoimmune neuritis rats

T-regulatory cells expressing the forkhead box transcription factor 3 (Foxp3) play essential roles in immune homeostasis. Experimental autoimmune neuritis (EAN) is an autoantigen-specific T-cell-mediated disease model for human demyelinating inflammatory disease of the peripheral nervous system. We investigated the distribution of Foxp3 + cells in sciatic nerves, spleen and lymph nodes of EAN rats, and the influence of FTY720 on the localization of Foxp3 + cells in EAN rats. In sciatic nerves of EAN rats, accumulation of Foxp3 + cells was not seen during the pre-symptomatic phase (until Day 9) or during early or peak disease activity. In contrast, Foxp3 + cell accumulation was regularly seen in the recovery from neurologic disease, suggesting a contribution of Foxp3 + cells to the resolution of EAN. FTY720 was given at onset of EAN (Day 10) until Day 18. Following FTY720 administration, percentages of Foxp3 + cells in EAN rats were increased in circulating blood, but reduced in lymph nodes compared to the PBS control. FTY720 treatment suppressed total numbers but increased percentages of Foxp3 + cells in sciatic nerves of EAN rats. These data not only suggests a protective role of Foxp3 + cells in EAN but also provides a potential way to alter localization of Foxp3 + cells in vivo.

Regulatory Role of B Cells in a Murine Model of Allergic Airway Disease

Mice sensitized to OVA and subjected to acute OVA aerosol exposures develop allergic airway disease (AAD). However, chronic continuous Ag exposure results in resolution of AAD and the development of local inhalational tolerance (LIT). Because we have previously observed the persistence of B cells in the bronchoalveolar lavage (BAL) and hilar lymph nodes (HLN) at the resolution stage of this model, we investigated the role of B cells in the modulation of AAD. Although B cell-deficient mice developed LIT, adoptive transfer of HLN B cells from LIT mice to OVA-sensitized recipients resulted in attenuated AAD following subsequent OVA aerosol exposure, as determined by reduced BAL leukocytosis and eosinophilia, decreased tissue inflammation, and absent methacholine hyper-responsiveness. In similar adoptive transfer studies, HLN B cells from AAD mice were without effect. The protection transferred by LIT HLN B cells was Ag specific and was associated with accumulation of Foxp3(+) T regulatory cells regionally in BAL and HLN, but not systemically in the spleen. Fluorescent labeling of LIT HLN B cells before adoptive transfer demonstrated that these cells had the capacity to migrate to local inflammatory sites. In vitro assessment demonstrated that the LIT HLN B cells exerted this regulatory effect via TGF-beta induced conversion of CD4(+)CD25(-) T effector cells into functionally suppressive CD4(+)CD25(+)Foxp3(+) T regulatory cells. These findings illustrated a novel regulatory role for regional B cells in AAD and suggested a possible contributory role of B cells, along with other cell types, in the establishment of LIT.

Histamine 4 Receptor Activation Induces Recruitment of FoxP3+ T Cells and Inhibits Allergic Asthma in a Murine Model

Histamine has an important role in regulation of immune response which is mediated by differential expression of four distinct receptors, H1R-H4R. H1R and HR2 have previously been shown to be involved with modulation of lung inflammation. H4R is also expressed on inflammatory cells; therefore, we investigated the potential role of H4R in development of allergic asthma in a murine model. We determined that the H4R agonist 4-methylhistamine when delivered intratracheally before Ag challenge mitigated airway hyperreactivity and inflammation. This was associated with an increase in IL-10 and IFN-gamma, but not TGF-beta or IL-16, as well as a decrease in IL-13 in the bronchoalveolar lavage fluid. We also observed that H4R agonist instillation resulted in accumulation of FoxP3(+) T cells suggesting a direct effect on T regulatory cell recruitment. To investigate this further, we determined the in vitro effect of H4R stimulation on human T cell migration. The H4R agonist induced a 2- to 3-fold increase in T cell migration, similar to that seen for H1R agonists. Cells transmigrating to the H4R agonist, but not H1R, were skewed toward a CD4 cell expressing CD25 and intracellular FoxP3. H4R-responsive cells suppressed proliferation of autologous T cells, an effect that was dependent on IL-10 production. We conclude that H4R stimulation enriches for a regulatory T cell with potent suppressive activity for proliferation. These findings identify a novel function for H4R and suggest a potential therapeutic approach to attenuation of asthmatic inflammation.

Origin and Dynamics of Tumor-Associated Foxp3+ Regulatory T Cells (49.4)

Abstract Regulatory T cells (Tregs) expressing the forkhead transcription factor Foxp3 play a central role in the dominant control of immunological tolerance. Compelling evidence obtained from both animal and clinical studies have now linked the expansion and accumulation of Foxp3+ Tregs at the tumor site to the failure of immune-mediated tumor rejection. However, little is known regarding tumor-associated Foxp3+ Tregs within tumor tissues. Using both subcutaneous (s.c.) tumor and lung metastasis models of MCA-205 fibrosarcoma, we have found that tumor-associated Foxp3+ Tregs are highly activated and undergo vigorous cellular proliferation. Tumor-associated Foxp3+ Tregs were also found to be more potent functionally by in-vitro suppression assays and express higher levels of membrane-bound TGF-b1. To visualize endogenous Foxp3+ Tregs, we have generated Foxp3-GFP transgenic reporter mice by inserting GFP into a bacterial artificial chromosome (BAC) encompassing the Foxp3 locus. Using multi-photon microscopy, we observed a rapid recruitment and accumulation of Foxp3+ Tregs to the nascent lung tumor metastasis as early as 3 days after tumor inoculation. Intravital imaging of established s.c. tumors revealed a distinctive behavior of Foxp3+Tregs: the suppressor cells form a well-defined periperipheral layer encasing the tumor mass, moving rapidly within the superficial plain but not perpendicularly in and out of the tumor. Together, these data highlight that tumor-associated Foxp3+ Tregs are highly dynamic in function, behavior, and origin, perhaps contributing to overall poor immunogenicty of tumors.

Th3 Cells in Peripheral Tolerance. II. TGF-β-Transgenic Th3 Cells Rescue IL-2-Deficient Mice from Autoimmunity

We developed a transgenic (Tg) mouse that expresses TGF-beta under control of the IL-2 promoter to investigate Th3 cell differentiation both in vitro and in vivo. We previously found that repetitive in vitro Ag stimulation results in constant expression of Foxp3 in TGF-beta-Tg Th3 cells that acquire regulatory function independent of surface expression of CD25. To examine the differentiation and function of Th3 cells in vivo and to compare them with thymic-derived CD4(+)CD25(+) regulatory T cells (Treg), we introduced the TGF-beta transgene into T cells of IL-2-deficient (IL-2(-/-)) mice. We found that the induction, differentiation, and function of TGF-beta-derived Foxp3(+) Th3 cells were independent of IL-2, which differs from thymic Tregs. In an environment that lacks functional CD25(+) thymic-derived Tregs, expression of the TGF-beta transgene in IL-2(-/-) mice led to the induction of distinct CD25(-) regulatory cells in the periphery. These cells expressed Foxp3 and efficiently controlled hyperproliferation of T cells and rescued the IL-2(-/-) mouse from lethal autoimmunity. Unlike IL-2(-/-) animals, TGF-beta/IL-2(-/-) mice had normal numbers of T cells, B cells, macrophages, and dendritic cells and did not have splenomegaly, lymphadenopathy, or inflammation in multiple organs. Accumulation of Foxp3(+) cells over time, however, was dependent on IL-2. Our results suggest that TGF-beta-derived Foxp3(+)CD25(+/-) Th3 regulatory cells represent a different cell lineage from thymic-derived CD25(+) Tregs in the periphery but may play an important role in maintaining thymic Tregs in the peripheral immune compartment by secretion of TGF-beta.

Immunomodulatory effects associated with a live vaccine against Leishmania major containing CpG oligodeoxynucleotides

The inoculation of live Leishmania major to produce a lesion that heals (leishmanization) is to date the only vaccine against cutaneous leishmaniasis that has proven effective in humans, but it still has an unacceptable frequency of large ulcerating lesions that are slow to heal or, in rare cases, non-healing. We have previously shown that C57BL/6 mice vaccinated intradermally with 10(4) L. major/50 microg CpG oligodeoxynucleotides develop little or no dermal lesions and show early containment of parasite growth in the vaccination site, eliminating safety concerns related to the inoculation of live organisms. The addition of CpG to the live vaccine resulted in early activation of dermal dendritic cells and increased IL-6 production, as well as in a reduction in the accumulation of Foxp3(+)CD4(+)CD25(+) regulatory T (T(reg)) cells that naturally occurs in the skin following Leishmania infection. Neutralization of IL-6 caused the development of larger lesions and increased local T(reg) cell numbers. Transfer of vaccine-primed dendritic cells into IL-6-deficient mice mitigated lesion development, indicating that IL-6 reconstitution limited pathology in the vaccination site.