Regulatory T cells in the central nervous system.
TL;DR: Understanding how tumors induce Treg function to escape immune surveillance in marked contrast to autoimmune diseases will provide valuable lessons regarding Treg biology and potential therapeutic targets for CNS diseases.
Abstract: Regulatory T cells (Tregs) are critical to the human immune system, providing appropriately scaled immune responses and mediating peripheral tolerance. A central role for forkhead box protein 3 (FoxP3)(+) Tregs has been shown in the pathogenesis of mechanistically diverse central nervous system (CNS) diseases from autoimmune diseases such as multiple sclerosis to glioblastomas. Understanding how tumors induce Treg function to escape immune surveillance in marked contrast to autoimmune diseases, where there is loss of Treg function, will provide valuable lessons regarding Treg biology and potential therapeutic targets for CNS diseases.
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TL;DR: The recent developments in CD4(+) T cell plasticity are discussed with a focus on Treg and Th17 cells and its role in human autoimmune disease, in particular multiple sclerosis (MS).
314 citations
TL;DR: The most potent drug for inhibiting relapses, the humanized anti-α4 integrin antibody known as Natalizumab, blocks homing of mononuclear cells to the CNS and provides a strong foundation for understanding the pathobiology of the relapse.
Abstract: Eighty percent of individuals with multiple sclerosis (MS) initially develop a clinical pattern with periodic relapses followed by remissions, called relapsing-remitting MS (RRMS). This period of fluctuating disease may last for a decade or more. Clinical relapses reflect acute inflammation in the central nervous system (CNS), composed of the brain and spinal cord. Often, different anatomic areas in the CNS are involved each time a relapse occurs, resulting in varied clinical manifestations in each instance. Relapses are nearly always followed by some degree of remission, though recovery to baseline status before the flare is often incomplete. There are nine approved drugs for treatment of RRMS. The most potent drug for inhibiting relapses, the humanized anti-α4 integrin antibody known as Natalizumab, blocks homing of mononuclear cells to the CNS. The mechanisms of action of the approved drugs for RRMS provide a strong foundation for understanding the pathobiology of the relapse. Despite substantial progress in controlling relapses with the current armamentarium of medications, there is much to learn and ever more effective and safe therapies to develop.
256 citations
TL;DR: The Th17/Th1 paradigm as mentioned in this paper was proposed to investigate the role of Th17 cells in the early stages of MS/EAE in an animal model of multiple sclerosis.
225 citations
Cites background from "Regulatory T cells in the central n..."
...preventing autoimmunity and by dampening or quenching anti-microbial immune responses that can harm the organism if they become exaggerated, or are unnecessary after infection has been cleared (159)....
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TL;DR: The role of CD4+ regulatory T cells in autoimmune neuroinflammation with an emphasis on Tregs and Tr1 cells in MS is discussed.
Abstract: Regulatory T cells are the central element for the maintenance of peripheral tolerance. Several subtypes of regulatory T (Treg) cells have been described, and most of them belong to the CD4(+) T-helper (Th) cell lineage. These specific subtypes can be discriminated according to phenotype and function. Forkhead box protein 3 (FoxP3)-expressing natural Treg cells (Tregs) and IL-10-producing, T-regulatory type 1 cells (Tr1) are the best-studied types of CD4(+) regulatory T cells in humans and experimental animal models. It was shown that they play a crucial role during autoimmune neuroinflammation. Both cells types seem to be particularly important for multiple sclerosis (MS). Here, we discuss the role of CD4(+) regulatory T cells in autoimmune neuroinflammation with an emphasis on Tregs and Tr1 cells in MS.
177 citations
TL;DR: The data suggest that IRT5 probiotics could be applicable to modulate T cell mediated neuronal autoimmune diseases, including multiple sclerosis.
166 citations
Cites background from "Regulatory T cells in the central n..."
...In addition, depletion of Foxp3+ Treg cells decreased threshold of antigen required for the development of EAE and prevented efficient recovery, inversely, transfer of CD4+CD25+ Treg cells reduced disease severity in EAE [8]....
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References
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TL;DR: Foxp3, which encodes a transcription factor that is genetically defective in an autoimmune and inflammatory syndrome in humans and mice, is specifically expressed in naturally arising CD4+ regulatory T cells and retroviral gene transfer of Foxp3 converts naïve T cells toward a regulatory T cell phenotype similar to that of naturally occurring CD4+.
Abstract: Regulatory T cells engage in the maintenance of immunological self-tolerance by actively suppressing self-reactive lymphocytes. Little is known, however, about the molecular mechanism of their development. Here we show that Foxp3, which encodes a transcription factor that is genetically defective in an autoimmune and inflammatory syndrome in humans and mice, is specifically expressed in naturally arising CD4+ regulatory T cells. Furthermore, retroviral gene transfer of Foxp3 converts naive T cells toward a regulatory T cell phenotype similar to that of naturally occurring CD4+ regulatory T cells. Thus, Foxp3 is a key regulatory gene for the development of regulatory T cells.
8,082 citations
TL;DR: It is reported that the forkhead transcription factor Foxp3 is specifically expressed in CD4+CD25+ regulatory T cells and is required for their development and function and ectopic expression ofFoxp3 confers suppressor function on peripheral CD4-CD25− T cells.
Abstract: CD4+CD25+ regulatory T cells are essential for the active suppression of autoimmunity. Here we report that the forkhead transcription factor Foxp3 is specifically expressed in CD4+CD25+ regulatory T cells and is required for their development. The lethal autoimmune syndrome observed in Foxp3-mutant scurfy mice and Foxp3-null mice results from a CD4+CD25+ regulatory T cell deficiency and not from a cell-intrinsic defect of CD4+CD25- T cells. CD4+CD25+ regulatory T cells rescue disease development and preferentially expand when transferred into neonatal Foxp3-deficient mice. Furthermore, ectopic expression of Foxp3 confers suppressor function on peripheral CD4+CD25- T cells. Thus, Foxp3 is a critical regulator of CD4+CD25+ regulatory T cell development and function.
7,321 citations
TL;DR: The authors showed that CD4+CD25+ cells contribute to maintaining self-tolerance by downregulating immune response to self and non-self Ags in an Ag-nonspecific manner, presumably at the T cell activation stage.
Abstract: Approximately 10% of peripheral CD4+ cells and less than 1% of CD8+ cells in normal unimmunized adult mice express the IL-2 receptor alpha-chain (CD25) molecules. When CD4+ cell suspensions prepared from BALB/c nu/+ mice lymph nodes and spleens were depleted of CD25+ cells by specific mAb and C, and then inoculated into BALB/c athymic nude (nu/nu) mice, all recipients spontaneously developed histologically and serologically evident autoimmune diseases (such as thyroiditis, gastritis, insulitis, sialoadenitis, adrenalitis, oophoritis, glomerulonephritis, and polyarthritis); some mice also developed graft-vs-host-like wasting disease. Reconstitution of CD4+CD25+ cells within a limited period after transfer of CD4+CD25- cells prevented these autoimmune developments in a dose-dependent fashion, whereas the reconstitution several days later, or inoculation of an equivalent dose of CD8+ cells, was far less efficient for the prevention. When nu/nu mice were transplanted with allogeneic skins or immunized with xenogeneic proteins at the time of CD25- cell inoculation, they showed significantly heightened immune responses to the skins or proteins, and reconstitution of CD4+CD25+ cells normalized the responses. Taken together, these results indicate that CD4+CD25+ cells contribute to maintaining self-tolerance by down-regulating immune response to self and non-self Ags in an Ag-nonspecific manner, presumably at the T cell activation stage; elimination/reduction of CD4+CD25+ cells relieves this general suppression, thereby not only enhancing immune responses to non-self Ags, but also eliciting autoimmune responses to certain self-Ags. Abnormality of this T cell-mediated mechanism of peripheral tolerance can be a possible cause of various autoimmune diseases.
5,929 citations
TL;DR: It is shown, in detailed studies of CD4+CD25+FOXP3+ Treg cells in 104 individuals affected with ovarian carcinoma, that human tumor T Reg cells suppress tumor-specific T cell immunity and contribute to growth of human tumors in vivo.
Abstract: Regulatory T (T(reg)) cells mediate homeostatic peripheral tolerance by suppressing autoreactive T cells. Failure of host antitumor immunity may be caused by exaggerated suppression of tumor-associated antigen-reactive lymphocytes mediated by T(reg) cells; however, definitive evidence that T(reg) cells have an immunopathological role in human cancer is lacking. Here we show, in detailed studies of CD4(+)CD25(+)FOXP3(+) T(reg) cells in 104 individuals affected with ovarian carcinoma, that human tumor T(reg) cells suppress tumor-specific T cell immunity and contribute to growth of human tumors in vivo. We also show that tumor T(reg) cells are associated with a high death hazard and reduced survival. Human T(reg) cells preferentially move to and accumulate in tumors and ascites, but rarely enter draining lymph nodes in later cancer stages. Tumor cells and microenvironmental macrophages produce the chemokine CCL22, which mediates trafficking of T(reg) cells to the tumor. This specific recruitment of T(reg) cells represents a mechanism by which tumors may foster immune privilege. Thus, blocking T(reg) cell migration or function may help to defeat human cancer.
4,795 citations
"Regulatory T cells in the central n..." refers background in this paper
...Although depletion of the Treg population inhibits recovery of the animals (147), their suppressive ability remains unclear: Tregs taken from one model at peak of disease were unable to suppress CNS-derived effector T cells (146) but from another, CNS-derived Tregs taken from the 2012 John Wiley & Sons A/S 162 Immunological Reviews 248/2012 CNS during the recovery phase of EAE could suppress MOGspecific IFNc, but not IL-17 in vitro (148)....
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...We and others (53–55) have observed human Tregs capable of releasing the pro-inflammatory cytokine IL-17, and non-regulatory cells that are CD25+CD127low have also been described that secrete either IFNc or IL-17 (38, 56)....
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...This recruitment has been shown to be driven by CCL2 and CCL22 secreted by the tumor and macrophages in both glioblastoma multiforme (GBM) and ovarian cancer (149, 153), but the presence of Tregs is secondary to the release of CCL2, implying that Tregs may be necessary for the growth of tumors, but not their initial establishment (160)....
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...Recently, we showed that FoxP3+ Tregs were capable of producing IFNc ex vivo and that there was a higher frequency of these cells in untreated patients with RRMS as compared with healthy controls (136) (Fig....
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...In ovarian cancer, a decreased ratio of CD8 T cells to Tregs in tumors is correlated with poor prognosis, and Tregs are able to inhibit tumor infiltrating T cells by reducing production of IL-12 and IFNc (149)....
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TL;DR: The Phase II HapMap is described, which characterizes over 3.1 million human single nucleotide polymorphisms genotyped in 270 individuals from four geographically diverse populations and includes 25–35% of common SNP variation in the populations surveyed, and increased differentiation at non-synonymous, compared to synonymous, SNPs is demonstrated.
Abstract: We describe the Phase II HapMap, which characterizes over 3.1 million human single nucleotide polymorphisms (SNPs) genotyped in 270 individuals from four geographically diverse populations and includes 25-35% of common SNP variation in the populations surveyed. The map is estimated to capture untyped common variation with an average maximum r2 of between 0.9 and 0.96 depending on population. We demonstrate that the current generation of commercial genome-wide genotyping products captures common Phase II SNPs with an average maximum r2 of up to 0.8 in African and up to 0.95 in non-African populations, and that potential gains in power in association studies can be obtained through imputation. These data also reveal novel aspects of the structure of linkage disequilibrium. We show that 10-30% of pairs of individuals within a population share at least one region of extended genetic identity arising from recent ancestry and that up to 1% of all common variants are untaggable, primarily because they lie within recombination hotspots. We show that recombination rates vary systematically around genes and between genes of different function. Finally, we demonstrate increased differentiation at non-synonymous, compared to synonymous, SNPs, resulting from systematic differences in the strength or efficacy of natural selection between populations.
4,565 citations
"Regulatory T cells in the central n..." refers background in this paper
...This identification of risk alleles for MS has only been possible in the years following the complete sequencing of the human genome and the publication of the Haplotype Map (Hapmap) (109, 110)....
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