• Clinical and Experimental Pediatrics
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• v.50 no.12
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• pp.1165-1172
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• 2007

Self/non-self discrimination and unresponsiveness to self is the fundamental properties of the immune system. Self-tolerance is a state in which the individual is incapable of developing an immune response to an individual's own antigens and it underlies the ability to remain tolerant of individual's own tissue components. Several mechanisms have been postulated to explain the tolerant state. They can be broadly classified into two groups: central tolerance and peripheral tolerance. Several mechanisms exist, some of which are shared between T cells and B cells. In central tolerance, the recognition of self-antigen by lymphocytes in bone marrow or thymus during development is required, resulting in receptor editing (revision), clonal deletion, anergy or generation of regulatory T cells. Not all self-reactive B or T cells are centrally purged from the repertoire. Additional mechanisms of peripheral tolerance are required, such as anergy, suppression, deletion or clonal ignorance. Tolerance is antigen specific. Generating and maintaining the self-tolerance for T cells and B cells are complex. Failure of self-tolerance results in immune responses against self-antigens. Such reactions are called autoimmunity and may give rise to autoimmune diseases. Development of autoimmune disease is affected by properties of the genes of the individual and the environment, both infectious and non-infectious. The host's genes affect its susceptibility to autoimmunity and the environmental factors promote the activation of self-reactive lymphocytes, developing the autoimmunity. The changes in participating antigens (epitope spreading), cells, cytokines or other inflammatory mediators contribute to the progress from initial activation to a chronic state of autoimmune diseases.

• Parasites, Hosts and Diseases
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• v.54 no.2
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• pp.163-171
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• 2016

As most infections by the helminth parasite elicit the recruitment of $CD4^+CD25^+Foxp3^+$ T ($T_{reg}$) cells, many scientists have suggested that these cells could be used for the treatment of immune-mediated inflammation and associated diseases. In order to investigate the distribution and alteration of activated $T_{reg}$ cells, we compared the expression levels of $T_{reg}$ cell activation markers in the ileum and gastrocnemius tissues 1, 2, and 4 weeks after infection. The number of $T_{reg}$ cells was monitored using GFP-coded Foxp3 transgenic mice. In mice at 1 week after Trichinella spiralis infection, the number of activated $T_{reg}$ cells was higher than in the control group. In mice at 2 weeks after infection, there was a significant increase in the number of cells expressing Foxp3 and CTLA-4 when compared to the control group and mice at 1 week after infection. At 4 weeks after infection, T. spiralis was easily identifiable in nurse cells in mouse muscles. In the intestine, the expression of Gzmb and Klrg1 decreased over time and that of Capg remained unchanged for the first and second week, then decreased in the 4th week. However, in the muscles, the expression of most chemokine genes was increased due to T. spiralis infection, in particular the expression levels of Gzmb, OX40, and CTLA-4 increased until week 4. In addition, increased gene expression of all chemokine receptors in muscle, CXCR3, CCR4, CCR5, CCR9, and CCR10, was observed up until the 4th week. In conclusion, various chemokine receptors showed increased expressions combined with recruitment of $T_{reg}$ cells in the muscle tissue.

• IMMUNE NETWORK
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• v.14 no.6
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• pp.277-288
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• 2014

T cells are central players in the regulation of adaptive immunity and immune tolerance. In the periphery, T cell differentiation for maturation and effector function is regulated by a number of factors. Various factors such as antigens, co-stimulation signals, and cytokines regulate T cell differentiation into functionally specialized effector and regulatory T cells. Other factors such as nutrients, micronutrients, nuclear hormones and microbial products provide important environmental cues for T cell differentiation. A mounting body of evidence indicates that the microbial metabolites short-chain fatty acids (SCFAs) have profound effects on T cells and directly and indirectly regulate their differentiation. We review the current status of our understanding of SCFA functions in regulation of peripheral T cell activity and discuss their impact on tissue inflammation.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.28 no.4
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• pp.92-110
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• 2015

Objectives : The water extract of Bowon-tang composited with thePanax, AstragalusandGlycyrrhiza Radixhas been traditionally used for treatment of a sickly child and smallpox in oriental medicine. However, little is known about the regulatory effects of Bowon-tang on the production, expression and activity of immune mediators [nitric oxide, prostaglandin E2, inducible nitric oxide synthetase, cyclooxygenase-2], the macrophage activation factor production, the proliferation, subset expression, the killing activity, and the capping in immune cells.Methods : In this study, we investigated the effects of water extracts from Bowon-tang,Panax, AstragalusorGRin mouse immune cells or human Jurkat T cells. Each extract (25-200 ㎍/㎖)perse had no cytotoxic effect in unstimulated macrophages, but concentration-dependently regulated NO and PGE₂production, iNOS expression, and COX-2 activity in mouse peritoneal macrophages with MAF stimulation. These regulatory effects were synergistically increased by their combination (Bowon-tang).Results : The extract of Bowon-tang concentration-dependently regulated T cell proliferation, CD4⁺and CD8⁺expression, and NK killing activity in mouse splenocytes and capping in Jurkat T cells.Conclusions : These results suggest that the water extract of Bowon-tang composited with thePanax, AstragalusandGRmay be useful for therapeutic drugs against a sickly constitution and immune diseases, probably by regulating the production of immune mediators.

• BMB Reports
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• v.50 no.1
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• pp.49-54
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• 2017

Previously, we reported that vitamin C facilitates the CpG demethylation of Foxp3 enhancer in $CD4^+Foxp3^+$ regulatory T cells (Tregs) by enhancing the activity of a DNA demethylase ten-eleven-translocation (Tet). However, it is not clear whether vitamin C affects other helper T cell lineages like T helper type 17 (Th17) cells which are related with Tregs. Here, we show that the expression of interleukin-17A (IL17) increases with the treatment of vitamin C but not with other antioxidants. Interestingly, the upregulation of IL17 was not accompanied by DNA demethylation in Il17 promoter and was independent of Tet enzymes. Rather, vitamin C reduced the trimethylation of histone H3 lysine 9 (H3K9me3) in the regulatory elements of the Il17 locus, and the effects of vitamin C were abrogated by knockdown of jumonji-C domain-containing protein 2 (jmjd2). These results suggest that vitamin C can affect the expression of IL17 by modulating the histone demethylase activity.

• BLOOD RESEARCH
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• v.53 no.4
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• pp.294-298
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• 2018

Background Production of immunosuppressive enzymes such as indoleamine 2,3-dioxygenase (IDO) is one of the strategies employed by hematologic malignancies, including acute myeloid leukemia (AML), to circumvent immune surveillance. Moreover, IDO has the ability to convert $CD4^+CD25^-$ conventional T cells into regulatory T cells (Tregs). In this study, we evaluated the expression of IDO in cytogenetically normal acute myeloid leukemia (CN-AML) patients and its correlation with the Treg marker, FOXP3, as well as clinical and laboratory parameters. Methods Thirty-seven newly diagnosed CN-AML patients were enrolled in our study along with 22 healthy individuals. The expression of the IDO and FOXP3 genes was analyzed by SYBR Green real-time PCR. Results Both IDO and FOXP3 were highly upregulated in CN-AML patients compared to control groups (P=0.004 and P=0.031, respectively). A positive correlation was observed between IDO and FOXP3 expression among AML patients (r=0.512, P=0.001). Expression of IDO and FOXP3 showed no significant correlation with laboratory parameters such as white blood cell and platelet counts, hemoglobin levels, bone marrow blast percentage, gender, and FLT3 mutation status (P>0.05). Conclusion Higher IDO expression in CN-AML patients may be associated with an increased Treg phenotype which may promote disease progression and lead to poor prognosis of CN-AML patients.

• Journal of Periodontal and Implant Science
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• v.44 no.5
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• pp.235-241
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• 2014

Purpose: Regulatory T cells (Tregs), expressing CD4 and CD25 as well as Foxp3, are known to play a pivotal role in immunoregulatory function in autoimmune diseases, cancers, and graft rejection. Dendritic cells (DCs) are considered the major antigen-presenting cells (APCs) for initiating these T-cell immune responses, of which $CD103^+$ DCs are derived from precursor human peripheral blood mononuclear cells (PBMCs). The aim of the present study was to evaluate the capacity of these PBMC-derived $CD103^+$ DCs to promote the differentiation of antigen-specific Tregs. Methods: Monocyte-derived DCs were induced from $CD14^+$ monocytes from the PBMCs of 10 healthy subjects. Once the $CD103^+$ DCs were purified, the cell population was enriched by adding retinoic acid (RA). Peptide numbers 14 and 19 of Porphyromonas gingivalis heat shock protein 60 (HSP60) were synthesized to pulse $CD103^+$ DCs as a tool for presenting the peptide antigens to stimulate $CD3^+$ T cells that were isolated from human PBMC. Exogenous interleukin 2 was added as a coculture supplement. The antigen-specific T-cell lines established were phenotypically identified for their expression of CD4, CD25, or Foxp3. Results: When PBMCs were used as APCs, they demonstrated only a marginal capacity to stimulate peptide-specific Tregs, whereas $CD103^+$ DCs showed a potent antigen presenting capability to promote the peptide-specific Tregs, especially for peptide 14. RA enhanced the conversion of $CD103^+$ DCs, which paralleled the antigen-specific Treg-stimulating effect, though the differences failed to reach statistical significance. Conclusions: We demonstrated that $CD103^+$ DCs can promote antigen-specific Tregs from naive T cells, when used as APCs for an epitope peptide from P. gingivalis HSP60. RA was an effective reagent that induces mature DCs with the typical phenotypic expression of CD103 that demonstrated the functional capability to promote antigen-specific Tregs.

• Biomedical Science Letters
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• v.21 no.2
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• pp.60-68
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• 2015

NecroX-7 is a novel small compound of the NecroX series based on the indole moiety, which has potent cytoprotective and antioxidant properties. We previously detected potential immune regulatory effects of NecroX-7 in immune related diseases like Graft-versus-Host Disease. However, the function and the underlying mechanisms of immunological effects of NecroX-7 in the immune system have not been well established. In this study, we investigated the immune response characterization of differentially expressed genes of NecroX-7 administration in $CD4^+$ T cells by microarray analysis. $CD4^+$ T cells stimulated with NecroX-7 ($40{\mu}M$) or vehicle for 72 hours resulted in the identification of 337 differentially expressed genes (1.5 fold, P<0.05) by expression profiling analysis. Twenty eight of the explored NecroX-7-regulated genes were related to immune system processes. These genes were validated by quantitative real-time PCR. The most significant genes were glutathione reductase, eukaryotic translation elongation factor 1, lymphotoxin-alpha, heat shock protein 9 and chloride intracellular channel protein 4. These findings demonstrate the strongly immune response of NecroX-7 in $CD4^+$ T cells, suggesting that cytoprotection and immune regulation may underlie the critical aspects of NecroX-7 exposure.

• IMMUNE NETWORK
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• v.22 no.1
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• pp.10.1-10.17
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• 2022

Systemic autoimmune diseases arise from loss of self-tolerance and immune homeostasis between effector and regulator functions. There are many therapeutic modalities for autoimmune diseases ranging from conventional disease-modifying anti-rheumatic drugs and immunosuppressants exerting nonspecific immune suppression to targeted agents including biologic agents and small molecule inhibitors aiming at specific cytokines and intracellular signal pathways. However, such current therapeutic strategies can rarely induce recovery of immune tolerance in autoimmune disease patients. To overcome limitations of conventional treatment modalities, novel approaches using specific cell populations with immune-regulatory properties have been attempted to attenuate autoimmunity. Recently progressed biotechnologies enable sufficient in vitro expansion and proper manipulation of such 'tolerogenic' cell populations to be considered for clinical application. We introduce 3 representative cell types with immunosuppressive features, including mesenchymal stromal cells, Tregs, and myeloid-derived suppressor cells. Their cellular definitions, characteristics, mechanisms of immune regulation, and recent data about preclinical and clinical studies in systemic autoimmune diseases are reviewed here. Challenges and limitations of each cell therapy are also addressed.

• IMMUNE NETWORK
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• v.24 no.1
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• pp.9.1-9.21
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• 2024

The cytokine IL-7 plays critical and nonredundant roles in T cell immunity so that the abundance and availability of IL-7 act as key regulatory mechanisms in T cell immunity. Importantly, IL-7 is not produced by T cells themselves but primarily by non-lymphoid lineage stromal cells and epithelial cells that are limited in their numbers. Thus, T cells depend on cell extrinsic IL-7, and the amount of in vivo IL-7 is considered a major factor in maximizing and maintaining the number of T cells in peripheral tissues. Moreover, IL-7 provides metabolic cues and promotes the survival of both naïve and memory T cells. Thus, IL-7 is also essential for the functional fitness of T cells. In this regard, there has been an extensive effort trying to increase the protein abundance of IL-7 in vivo, with the aim to augment T cell immunity and harness T cell functions in anti-tumor responses. Such approaches started under experimental animal models, but they recently culminated into clinical studies, with striking effects in re-establishing T cell immunity in immunocompromised patients, as well as boosting anti-tumor effects. Depending on the design, glycosylation, and the structure of recombinantly engineered IL-7 proteins and their mimetics, recombinant IL-7 molecules have shown dramatic differences in their stability, efficacy, cellular effects, and overall immune functions. The current review is aimed to summarize the past and present efforts in the field that led to clinical trials, and to highlight the therapeutical significance of IL-7 biology as a master regulator of T cell immunity.