• BMB Reports
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• 제44권4호
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• pp.217-231
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• 2011

T cell exhaustion develops under conditions of antigen-persistence caused by infection with various chronic pathogens, such as human immunodeficiency virus (HIV) and myco-bacterium tuberculosis (TB), or by the development of cancer. T cell exhaustion is characterized by stepwise and progressive loss of T cell function, which is probably the main reason for the failed immunological control of chronic pathogens and cancers. Recent observations have detailed some of the intrinsic and extrinsic factors that influence the severity of T cell exhaustion. Duration and magnitude of antigenic activation of T cells might be associated with up-regulation of inhibitory receptors, which is a major intrinsic factor of T cell exhaustion. Extrinsic factors might include the production of suppressive cytokines, T cell priming by either non-professional antigenpresenting cells (APCs) or tolerogenic dendritic cells (DCs), and alteration of regulatory T (Treg) cells. Further investigation of the cellular and molecular processes behind the development of T cell exhaustion can reveal therapeutic targets and strategies for the treatment of chronic infections and cancers. Here, we report the properties and the mechanisms of T cell exhaustion in a chronic environment.

• IMMUNE NETWORK
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• 제20권1호
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• pp.2.1-2.19
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• 2020

Acute viral infection or vaccination generates highly functional memory CD8 T cells following the Ag resolution. In contrast, persistent antigenic stimulation in chronic viral infection and cancer leads to a state of T-cell dysfunction termed T-cell exhaustion. We and other have recently identified a novel subset of exhausted CD8 T cells that act as stem cells for maintaining virus-specific CD8 T cells in a mouse model of chronic lymphocytic choriomeningitis virus infection. This stem cell-like CD8 T-cell subset has been also observed in both mouse and human tumor models. Most importantly, in both chronic viral infection and tumor models, the proliferative burst of Ag-specific CD8 T cells driven by PD-1-directed immunotherapy comes exclusively from this stem cell-like CD8 T-cell subset. Therefore, a better understanding of the mechanisms how CD8 T-cell subsets are regulated during chronic viral infection and cancer is required to improve the current immunotherapies that restore the function of exhausted CD8 T cells. In this review, we discuss the differentiation of virus-specific CD8 T cells during chronic viral infection, the characteristics and function of CD8 T-cell subsets, and the therapeutic intervention of PD-1-directed immunotherapy in cancer.

• IMMUNE NETWORK
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• 제23권1호
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• pp.9.1-9.15
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• 2023

Cancer immunotherapies continue to face numerous obstacles in the successful treatment of solid malignancies. While immunotherapy has emerged as an extremely effective treatment option for hematologic malignancies, it is largely ineffective against solid tumors due in part to metabolic challenges present in the tumor microenvironment (TME). Tumor-infiltrating CD8⁺ T cells face fierce competition with cancer cells for limited nutrients. The strong metabolic suppression in the TME often leads to impaired T-cell recruitment to the tumor site and hyporesponsive effector functions via T-cell exhaustion. Growing evidence suggests that mitochondria play a key role in CD8⁺ T-cell activation, migration, effector functions, and persistence in tumors. Therefore, targeting the mitochondrial metabolism of adoptively transferred T cells has the potential to greatly improve the effectiveness of cancer immunotherapies in treating solid malignancies.

• IMMUNE NETWORK
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• 제23권1호
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• pp.10.1-10.16
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• 2023

Memory T (Tm) cells protect against Ags that they have previously contacted with a fast and robust response. Therefore, developing long-lived Tm cells is a prime goal for many vaccines and therapies to treat human diseases. The remarkable characteristics of Tm cells have led scientists and clinicians to devise methods to make Tm cells more useful. Recently, Tm cells have been highlighted for their role in coronavirus disease 2019 vaccines during the ongoing global pandemic. The importance of Tm cells in cancer has been emerging. However, the precise characteristics and functions of Tm cells in these diseases are not completely understood. In this review, we summarize the known characteristics of Tm cells and their implications in the development of vaccines and immunotherapies for human diseases. In addition, we propose to exploit the beneficial characteristics of Tm cells to develop strategies for effective vaccines and overcome the obstacles of immunotherapy.

• IMMUNE NETWORK
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• 제24권1호
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• pp.5.1-5.19
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• 2024

The key role of T cells in cancer immunotherapy is well established and is highlighted by the remarkable capacity of Ab-mediated checkpoint blockade to overcome T-cell exhaustion and amplify anti-tumor responses. However, total or partial tumor remission following checkpoint blockade is still limited to only a few types of tumors. Hence, concerted attempts are being made to devise new methods for improving tumor immunity. Currently, much attention is being focused on therapy with IL-2. This cytokine is a powerful growth factor for T cells and optimises their effector functions. When used at therapeutic doses for cancer treatment, however, IL-2 is highly toxic. Nevertheless, recent work has shown that modifying the structure or presentation of IL-2 can reduce toxicity and lead to effective anti-tumor responses in synergy with checkpoint blockade. Here, we review the complex interaction of IL-2 with T cells: first during normal homeostasis, then during responses to pathogens, and finally in anti-tumor responses.

• Tuberculosis and Respiratory Diseases
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• 제87권1호
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• pp.22-30
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• 2024

Tumor immune evasion is a complex process that involves various mechanisms, such as antigen recognition restriction, immune system suppression, and T cell exhaustion. The tumor microenvironment contains various immune cells involved in immune evasion. Recent studies have demonstrated that granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) induce immune evasion in lung cancer by modulating neutrophils and myeloid-derived suppressor cells. Here we describe the origin and function of G-CSF and GM-CSF, particularly their role in immune evasion in lung cancer. In addition, their effects on programmed death-ligand 1 expression and clinical implications are discussed.

• IMMUNE NETWORK
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• 제20권1호
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• pp.6.1-6.20
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• 2020

IL-17 is produced by RAR-related orphan receptor gamma t (RORγt)-expressing cells including Th17 cells, subsets of γδT cells and innate lymphoid cells (ILCs). The biological significance of IL-17-producing cells is well-studied in contexts of inflammation, autoimmunity and host defense against infection. While most of available studies in tumor immunity mainly focused on the role of T-bet-expressing cells, including cytotoxic CD8⁺ T cells and NK cells, and their exhaustion status, the role of IL-17-producing cells remains poorly understood. While IL-17-producing T-cells were shown to be anti-tumorigenic in adoptive T-cell therapy settings, mice deficient in type 17 genes suggest a protumorigenic potential of IL-17-producing cells. This review discusses the features of IL-17-producing cells, of both lymphocytic and myeloid origins, as well as their suggested pro- and/or anti-tumorigenic functions in an organ-dependent context. Potential therapeutic approaches targeting these cells in the tumor microenvironment will also be discussed.

• Journal of Microbiology and Biotechnology
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• 제17권7호
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• pp.1162-1168
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• 2007

Although widely used as a host for recombinant protein production, Escherichia coli is unsuitable for massive screening of recombinant clones, owing to its poor secretion of proteins. A vector system containing T4 holin and T7 lysozyme genes under the control of the ptsG promoter derivative that is inducible in the absence of glucose was developed for programmed cell lysis of E. coli. Because E. coli harboring the vector grows well in the presence of glucose, but is lysed upon glucose exhaustion, the activity of the foreign gene expressed in E. coli can be monitored easily without an additional step for cell disruption after the foreign gene is expressed sufficiently with an appropriate concentration of glucose. The effectiveness of the vector was demonstrated by efficient screening of the amylase gene from a Bacillus subtilis genomic library. This vector system is expected to provide a more efficient and economic screening of bioactive products from DNA libraries in large quantities.

• IMMUNE NETWORK
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• 제20권1호
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• pp.11.1-11.14
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• 2020

Most patients with hepatocellular carcinoma (HCC) are diagnosed at an advanced stage of disease. Until recently, systemic treatment options that showed survival benefits in HCC have been limited to tyrosine kinase inhibitors, antibodies targeting oncogenic signaling pathways or VEGF receptors. The HCC tumor microenvironment is characterized by a dysfunction of the immune system through multiple mechanisms, including accumulation of various immunosuppressive factors, recruitment of regulatory T cells and myeloid-derived suppressor cells, and induction of T cell exhaustion accompanied with the interaction between immune checkpoint ligands and receptors. Immune checkpoint inhibitors (ICIs) have been interfered this interaction and have altered therapeutic landscape of multiple cancer types including HCC. In this review, we discuss the use of anti-PD-1, anti-PD-L1, and anti-CTLA-4 antibodies in the treatment of advanced HCC. However, ICIs as a single agent do not benefit a significant portion of patients. Therefore, various clinical trials are exploring possible synergistic effects of combinations of different ICIs (anti-PD-1/PD-L1 and anti-CTLA-4 antibodies) or ICIs and target agents. Combinations of ICIs with locoregional therapies may also improve therapeutic responses.

• Parasites, Hosts and Diseases
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• 제31권3호
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• pp.249-258
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• 1993

원발성 아메바성 수막뇌염을 야기하는 Naegleria fowleri를 사망율에 따라 $1{\;}{\times}{\;}10^4$개 아메바 영양형 접종군과. $1{\;}{\times}{\;}10^5$개 아메바 영양형 접종군으로 나누어 비장세포를 비특이 mitogen인 Phytohemagglutinin(PHA)과 특이항원인 N. fowleri Iysates로 자극하여 T 세포의 interleukin-2 생성정도를 측정하고 T 림프구의 아형 및 아세포화정도를 측정한 결과 N.fowleri 아메바 영양형 $1{\;}{\times}{\;}10^5$개 접종군에서의 마우스 사망율은 72.2%였으며 $1{\;}{\times}{\;}10^4$개 접종군에서의 마우스 사망율은 14.3%였다. 또한 IL릭 생성정도를 접종후 7, 14, 24일째 측정한 결과. 접종 후 14일째에는 두 실험군 모두에서 대조군과 비교하여 IL닉의 생성이 유의하게 감소하였으며 접종 후 24일째에는 두 실험군 모두에서 접종 후 14일째 보다는 증가하였으나 대조군과 비교하여 유의하게 억제되었다 비장세포내 T 림프구 아형의 변동은 전체 비장 림프구에 대한 $Thy-1.2^{+}{\;}T.{\;}L3T4^{+}{\;}T,{\;}Ly^{2+}{\;}T$ 세포는 N.fowleri아메바 영양형 $1{\;}{\times}{\;}10^5$개 접종군에서 접종 후 7일째 대조군과 비교하여 유의하게 증가하였고 접종 후 14일째와 24일째에는 대조군과 비교하여 유의한 차이가 없었다. 아메바 영양형 $1{\;}{\times}{\;}10^4$개를 접종시킨 실험군은 경과 일수에 관계없이 대조군과 비교하여 유의한 차이가 없었다. 비장세포내 T 세포의 DNA의 분획을 관찰한 결과 두 실험군 모두에서 접종 후 7일째에 S phase 분획이 가장 높이 증가하였으며 접종 후 14일과 24일째에도 대조군에 비하여는 유의하게 증가하여 있었다. 이상의 결과를 종합하여 볼 때, N.fowleri를 사망율을 기준으로 접종량을 달리하여 아메바 영양형 $1{\;}{\times}{\;}10^4$개 접종군과 $1{\;}{\times}{\;}10^5$개 접종군으로 나누어 접종하였을 때, 접종 후 7일을 전후하여 IL-2를 매개로 활성화되는 세포매개성 면역이 N.fowleri감염의 방어기작으로 작용하는 것으로 생각되며 아메바 접종 후 14일째에는 치명적인 수막뇌염으로 진행되어 비장세포의 IL-2의 생성능력이 매우 억제된 것으로 생각된다. 또한 IL-2 생성능력과 T 세포의 아세포화의 증가 및 T세포 아령의 수의 변동과는 잘 일치되지 않는 것으로 나타났다.