101
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Li T, Wong VKW, Yi XQ, Wong YF, Zhou H, Liu L. Pseudolaric acid B suppresses T lymphocyte activation through inhibition of NF-κB signaling pathway and p38 phosphorylation. J Cell Biochem 2009; 108:87-95. [DOI: 10.1002/jcb.22230] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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102
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Weng NP, Akbar AN, Goronzy J. CD28(-) T cells: their role in the age-associated decline of immune function. Trends Immunol 2009; 30:306-12. [PMID: 19540809 DOI: 10.1016/j.it.2009.03.013] [Citation(s) in RCA: 432] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2009] [Revised: 03/23/2009] [Accepted: 03/23/2009] [Indexed: 02/06/2023]
Abstract
The accumulation of CD28(-) T cells, particularly within the CD8 subset, is one of the most prominent changes during T-cell homeostasis and function associated with aging in humans. CD28, a major co-stimulatory receptor, is responsible for the optimal antigen-mediated T-cell activation, proliferation and survival of T cells. CD28(-) T cells exhibit reduced antigen receptor diversity, defective antigen-induced proliferation and a shorter replicative lifespan while showing enhanced cytotoxicity and regulatory functions. Gene expression analyses reveal profound changes of CD28(-) T cells in comparison to their CD28(+) counterparts and corroborate their functional differences. Here we review recent advances in our understanding of CD28(-) T cells and their role in the age-associated decline of immune function.
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Affiliation(s)
- Nan-Ping Weng
- Laboratory of Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA.
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103
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Milone MC, Fish JD, Carpenito C, Carroll RG, Binder GK, Teachey D, Samanta M, Lakhal M, Gloss B, Danet-Desnoyers G, Campana D, Riley JL, Grupp SA, June CH. Chimeric receptors containing CD137 signal transduction domains mediate enhanced survival of T cells and increased antileukemic efficacy in vivo. Mol Ther 2009; 17:1453-64. [PMID: 19384291 DOI: 10.1038/mt.2009.83] [Citation(s) in RCA: 855] [Impact Index Per Article: 57.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Persistence of T cells engineered with chimeric antigen receptors (CARs) has been a major barrier to use of these cells for molecularly targeted adoptive immunotherapy. To address this issue, we created a series of CARs that contain the T cell receptor-zeta (TCR-zeta) signal transduction domain with the CD28 and/or CD137 (4-1BB) intracellular domains in tandem. After short-term expansion, primary human T cells were subjected to lentiviral gene transfer, resulting in large numbers of cells with >85% CAR expression. In an immunodeficient mouse xenograft model of primary human pre-B-cell acute lymphoblastic leukemia, human T cells expressing anti-CD19 CARs containing CD137 exhibited the greatest antileukemic efficacy and prolonged (>6 months) survival in vivo, and were significantly more effective than cells expressing CARs containing TCR-zeta alone or CD28-zeta signaling receptors. We uncovered a previously unrecognized, antigen-independent effect of CARs expressing the CD137 cytoplasmic domain that likely contributes to the enhanced antileukemic efficacy and survival in tumor bearing mice. Furthermore, our studies revealed significant discrepancies between in vitro and in vivo surrogate measures of CAR efficacy. Together these results suggest that incorporation of the CD137 signaling domain in CARs should improve the persistence of CARs in the hematologic malignancies and hence maximize their antitumor activity.
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Affiliation(s)
- Michael C Milone
- Department of Pathology and Laboratory Medicine, Abramson Family Cancer Research Institute, University of Pennsylvania, Philadelphia, Pennsylvania 19104-5160, USA.
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104
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Abstract
In rheumatoid arthritis (RA), chronically stimulated T lymphocytes sustain tissue-destructive joint inflammation. Both naïve and memory T cells in RA are prematurely aged with accelerated loss of telomeres suggesting excessive proliferative pressure or inadequate telomeric maintenance. Upon stimulation, RA naïve CD4 T cells are defective in up-regulating telomerase activity (P < 0.0001) due to insufficient induction of the telomerase component human telomerase reverse transcriptase (hTERT); T cell activation and cell cycle progression are intact. Telomerase insufficiency does not affect memory T cells or CD34 hematopoietic stem cells and is present in untreated patients and independent from disease activity. Knockdown of hTERT in primary human T cells increases apoptotic propensity (P = 0.00005) and limits clonal burst (P = 0.0001) revealing a direct involvement of telomerase in T cell fate decisions. Naïve RA CD4 T cells stimulated through the T cell receptor are highly susceptible to apoptosis, expanding to smaller clonal size. Overexpression of ectopic hTERT in naïve RA T cells conveys apoptotic resistance (P = 0.008) and restores proliferative expansion (P < 0.0001). Telomerase insufficiency in RA results in excessive T cell loss, undermining homeostatic control of the naive T cell compartment and setting the stage for lymphopenia-induced T cell repertoire remodeling. Restoring defective telomerase activity emerges as a therapeutic target in resetting immune abnormalities in RA.
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105
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Control of large, established tumor xenografts with genetically retargeted human T cells containing CD28 and CD137 domains. Proc Natl Acad Sci U S A 2009; 106:3360-5. [PMID: 19211796 DOI: 10.1073/pnas.0813101106] [Citation(s) in RCA: 664] [Impact Index Per Article: 44.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Mesothelin is a cell-surface molecule over-expressed on a large fraction of carcinomas, and thus is an attractive target of immunotherapy. A molecularly targeted therapy for these cancers was created by engineering T cells to express a chimeric receptor with high affinity for human mesothelin. Lentiviral vectors were used to express a single-chain variable fragment that binds mesothelin and that is fused to signaling domains derived from T-cell receptor zeta, CD28, and CD137 (4-1BB). When stimulated by mesothelin, lentivirally transduced T cells were induced to proliferate, express the antiapoptotic gene Bcl-X(L), and secrete multiple cytokines, all features characteristic of central memory T cells. When transferred intratumorally or intravenously into NOD/scid/IL2rgamma(-/-) mice engrafted with large pre-established tumors, the engineered T cells reduced the tumor burden, and in some cases resulted in complete eradication of the tumors at low effector-to-target ratios. Incorporation of the CD137 signaling domain specifically reprogrammed cells for multifunctional cytokine secretion and enhanced persistence of T cells. These findings have important implications for adoptive immunotherapy of cancer, especially in the context of poorly immunogenic tumors. Genetically redirected T cells have promise of targeting T lymphocytes to tumor antigens, confer resistance to the tumor microenvironment, and providing immunosurveillance.
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106
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Regulation of telomerase activity by interferon regulatory factors 4 and 8 in immune cells. Mol Cell Biol 2008; 29:929-41. [PMID: 19047367 DOI: 10.1128/mcb.00961-08] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Telomerase activity is downregulated in somatic cells but is upregulated during the activation of cells of the immune system. The mechanism of this reactivation is not well understood. In this study, we demonstrated that interferon regulatory factor 4 (IRF-4) and, to a lesser extent, IRF-8 induce telomerase activity. The suppression of IRF-4 results in decreased levels of TERT (telomerase reverse transcriptase) mRNA and telomerase activity and reduces cell proliferation. The overexpression of TERT compensates for this proliferation defect, suggesting that telomerase contributes to the regulation of cell proliferation by IRF-4. The induction of telomerase by IRF-4 and IRF-8 correlates with the activation of the TERT promoter. IRF-4 binds the interferon response-stimulated element and the gamma interferon-activated sequence composite binding site in the TERT core promoter region in vivo. Additionally, the binding of Sp1, Sp3, USF-1, USF-2, and c-Myc to the TERT promoter is elevated in cells expressing IRF-4. IRF-4, but not IRF-8, synergistically cooperates with Sp1 and Sp3 in the activation of the TERT promoter. Collectively, these results indicate that IRF-4 and IRF-8, two lymphoid cell-specific transcription factors, increase telomerase activity by activating TERT transcription in immune cells.
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107
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Ornish D, Lin J, Daubenmier J, Weidner G, Epel E, Kemp C, Magbanua MJM, Marlin R, Yglecias L, Carroll PR, Blackburn EH. Increased telomerase activity and comprehensive lifestyle changes: a pilot study. Lancet Oncol 2008; 9:1048-57. [DOI: 10.1016/s1470-2045(08)70234-1] [Citation(s) in RCA: 311] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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108
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Telomerase activity of HIV-1-specific CD8+ T cells: constitutive up-regulation in controllers and selective increase by blockade of PD ligand 1 in progressors. Blood 2008; 112:3679-87. [PMID: 18728248 DOI: 10.1182/blood-2008-01-135442] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Exhaustion of virus-specific T cells may play an important role in the pathophysiology of chronic viral infections. Here, we analyzed telomere length and telomerase activity in HIV-1-specific CD8+ T cells from progressors or controllers to determine underlying molecular pathways of T-cell exhaustion and senescence. Telomere lengths of HIV-1-specific CD8+ T cells from progressors were significantly shorter compared with autologous cytomegalovirus (CMV)/Epstein-Barr virus (EBV)-specific CD8+ T cells or bulk CD8+ T cells, while telomere lengths from controllers significantly exceeded those of autologous bulk CD8+ T cells and reached a similar level as HIV-1-specific CD8+ T cells collected during primary HIV-1 infection. Telomere length stabilization in controllers corresponded to high levels of constitutive telomerase activity, which was associated with preservation of cytotoxic and proliferative properties. Conversely, limited constitutive telomerase activity was observed in HIV-1-specific CD8+ T cells from progressors, although an increase in both telomere length and telomerase activity was achieved in antigenic-peptide-stimulated cells from progressors after blocking the PD-1/PD ligand 1 (PD-L1) pathway. Collectively, these data suggest a causal role of telomere shortening for the functional deficiencies of HIV-1-specific CD8+ T cells in chronic progressive infection, while high constitutive telomerase activities appears to contribute to maintenance of polyfunctional HIV-1-specific CD8+ T cells from HIV-1 controllers.
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109
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Abstract
Leukemia caused by retroviral insertional mutagenesis after stem cell gene transfer has been reported in several experimental animals and in patients treated for X-linked severe combined immunodeficiency. Here, we analyzed whether gene transfer into mature T cells bears the same genotoxic risk. To address this issue in an experimental "worst case scenario," we transduced mature T cells and hematopoietic progenitor cells from C57BL/6 (Ly5.1) donor mice with high copy numbers of gamma retroviral vectors encoding the potent T-cell oncogenes LMO2, TCL1, or DeltaTrkA, a constitutively active mutant of TrkA. After transplantation into RAG-1-deficient recipients (Ly5.2), animals that received stem cell transplants developed T-cell lymphoma/leukemia for all investigated oncogenes with a characteristic phenotype and after characteristic latency periods. Ligation-mediated polymerase chain reaction analysis revealed monoclonality or oligoclonality of the malignancies. In striking contrast, none of the mice that received T-cell transplants transduced with the same vectors developed leukemia/lymphoma despite persistence of gene-modified cells. Thus, our data provide direct evidence that mature T cells are less prone to transformation than hematopoietic progenitor cells.
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110
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Yang Y, An J, Weng NP. Telomerase is involved in IL-7-mediated differential survival of naive and memory CD4+ T cells. THE JOURNAL OF IMMUNOLOGY 2008; 180:3775-81. [PMID: 18322183 DOI: 10.4049/jimmunol.180.6.3775] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
IL-7 plays an essential role in T cell maintenance and survival. The survival effect of IL-7 is thought to be mediated through regulation of Bcl2 family proteins. After a comparative analysis of IL-7-induced growth and cell death of human naive and memory CD4(+) T cells, we observed that more memory CD4(+) T cells underwent cell division and proceeded to apoptosis than naive cells in response to IL-7. However, IL-7-induced expressions of Bcl2 family members (Bcl2, Bcl-x(L), Bax, and Bad) were similar between naive and memory cells. Instead, we found that IL-7 induced higher levels of telomerase activity in naive cells than in memory cells, and the levels of IL-7-induced telomerase activity had a significant inverse correlation with cell death in CD4(+) T cells. Furthermore, we showed that reducing expression of telomerase reverse transcriptase and telomerase activity significantly increased cell death of IL-7-cultured CD4(+) T cells. Together, these findings demonstrate that telomerase is involved in IL-7-mediated differential survival of naive and memory CD4(+) T cells.
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Affiliation(s)
- Yinhua Yang
- Laboratory of Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
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111
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Hara T, Matsumura-Arioka Y, Ohtani K, Nakamura M. Role of human T-cell leukemia virus type I Tax in expression of the human telomerase reverse transcriptase (hTERT) gene in human T-cells. Cancer Sci 2008; 99:1155-63. [PMID: 18422743 PMCID: PMC11159262 DOI: 10.1111/j.1349-7006.2008.00798.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 01/08/2008] [Accepted: 01/31/2008] [Indexed: 12/22/2022] Open
Abstract
The viral product Tax encoded by human T-cell leukemia virus type I (HTLV-I) is thought to play a central role in leukemogenesis. Clonal expansion of HTLV-I-infected cells requires the extension of cell division with telomere maintenance, which is regulated by the ribonucleoprotein enzyme telomerase. However, the roles of Tax in the expression of telomerase activity in T-cells remains controversial. Our previous study indicated that expression of the human telomerase reverse transcriptase subunit (hTERT) gene, which determines telomerase activity, is tightly regulated in human T-cells. In the present study, we investigated Tax-mediated regulation of hTERT gene expression by Tax in human T-cells. HTLV-I Tax induced expression of the hTERT gene in human peripheral blood leukocytes. Reporter assays revealed that Tax activated the hTERT promoter in quiescent Kit 225 cells, while the promoter activity was repressed by Tax in proliferating Jurkat cells. Both up-regulation and down-regulation by Tax were mediated through the 43-bp sequences in the promoter, which carried at least two elements that independently functioned as repressors. The two elements bound distinct factors. G1 to S phase transition induced by introduction of either cyclin D2 with cdk4 or p130-specific shRNA also activated the hTERT promoter, implying that activation of the hTERT promoter in quiescent Kit 225 cells is associated with cell cycle progression. Our findings suggest that the cell cycle state critically influences Tax-mediated regulation of hTERT expression.
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Affiliation(s)
- Toshifumi Hara
- Human Gene Sciences Center, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
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112
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Joshi NS, Kaech SM. Effector CD8 T cell development: a balancing act between memory cell potential and terminal differentiation. THE JOURNAL OF IMMUNOLOGY 2008; 180:1309-15. [PMID: 18209024 DOI: 10.4049/jimmunol.180.3.1309] [Citation(s) in RCA: 181] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Immune responses to infection are optimally designed to generate large numbers of effector T cells while simultaneously minimizing the collateral damage of their potentially lethal actions and generating memory T cells to protect against subsequent encounter with pathogens. Much remains to be discovered about how these equally essential processes are balanced to enhance health and longevity and, more specifically, what factors control effector T cell expansion, differentiation, and memory cell formation. The innate immune system plays a prominent role in the delicate balance of these decisions. Insights into these questions from recent work in the area of effector CD8 T cell differentiation will be discussed.
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Affiliation(s)
- Nikhil S Joshi
- Department of Immunobiology, Yale University School of Medicine, 300 Cedar Street, New Haven, CT 06520, USA
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113
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Yamada O, Ozaki K, Nakatake M, Akiyama M, Kawauchi K, Matsuoka R. Multistep regulation of telomerase during differentiation of HL60 cells. J Leukoc Biol 2008; 83:1240-8. [DOI: 10.1189/jlb.1207848] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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114
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Wang FZ, Sha L, Ye LH, Zhang XD. Promotion of cell proliferation by HBXIP via upregulation of human telomerase reverse transcriptase in human mesenchymal stem cells. Acta Pharmacol Sin 2008; 29:83-9. [PMID: 18158869 DOI: 10.1111/j.1745-7254.2008.00729.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
AIM We previously found that the hepatitis B X-interacting protein (HBXIP) was able to promote the proliferation of cells. Telomerase activity is known to be critical in cellular senescence and its level is modulated by the regulation of the telomerase catalytic subunit, telomerase reverse transcriptase (TERT), at both the transcriptional and post-transcriptional levels. To investigate the mechanism of promoting proliferation by HBXIP, the effect of HBXIP on human TERT (hTERT) was investigated in human mesenchymal stem cells (hMSC). METHODS BMMS-03 cells and hMSC from the bone marrow of a 4-month-old elicited fetus, were transiently transfected with the pcDNA3-hbxip plasmid encoding the HBXIP gene and pSilencer-hbxip plasmid encoding RNA interference (RNAi) targeting HBXIP mRNA, followed by the examination of the hTERT promoter reporter gene by luciferase assay, and the detection of telomerase activity by telomeric repeat amplication protocol, respectively, as well as the expression levels of hTERT, c-Myc, and Bcl-2 by Western blot analysis. RESULTS The overexpression of HBXIP led to a significant upregulation of hTERT promoter activity, telomerase activity, and the expression levels of hTERT, c-Myc, and Bcl-2 in BMMS-03 cells. RNAi targeting HBXIP mRNA produced the opposite results completely. CONCLUSION Our data demonstrated that HBXIP significantly stimulated the transcription and expression of hTERT and increased the activity of telomerase in BMMS-03 cells, which provides a new insight into the mechanism of promoting cell proliferation by HBXIP.
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Affiliation(s)
- Feng-ze Wang
- Departments of Biochemistry, Tianjin Key Laboratory of Microbial Functional Genomics, Institute for Molecular Biology, College of Life Sciences, Nankai University, Tianjin, China
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115
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Weng NP. Telomere and adaptive immunity. Mech Ageing Dev 2007; 129:60-6. [PMID: 18199471 DOI: 10.1016/j.mad.2007.11.005] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2007] [Revised: 11/15/2007] [Accepted: 11/28/2007] [Indexed: 12/23/2022]
Abstract
The adaptive immune response relies on the ability of lymphocytes to undergo periodic massive expansion. It is an enigma how lymphocytes are able to undergo this seemingly unlimited number of cell divisions. Telomeres and telomerase play a critical role in regulation of the replicative lifespan of cells, providing a potential mechanism which lymphocytes may employ. Here I will review the recent progress of the role of telomeres and telomerase in lymphocyte differentiation, function, and aging.
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Affiliation(s)
- Nan-ping Weng
- Laboratory of Immunology, National Institute on Aging, National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, MD 21224, United States.
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116
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Targonski PV, Caldwell CR, Strausbauch M, Wettstein P, Poland GA, Tangalos EG. White blood cell telomerase activity and incident respiratory illness among community-dwelling elderly vaccinated against seasonal influenza. Clin Pharmacol Ther 2007; 82:694-9. [PMID: 17971815 DOI: 10.1038/sj.clpt.6100410] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Immune cell telomerase activity may impact vaccine response in the elderly. Fifty persons aged 60-100 years were tested for post-influenza vaccination telomerase RNA expression (TERT) in peripheral blood mononuclear cells to assess for an association with influenza antibody levels and influenza-like illness or incident respiratory infection (IRI) in the year following vaccination. High rates of seroprotective influenza antibody (> or = 1:40 titers) were observed post-vaccination (86-92% to vaccine viral strains), with no association to TERT. No IRI occurred among persons in the top quartile of TERT expression, whereas the IRI rate was 33% in the lower three quartiles (Kaplan-Meier P=0.028). TERT expression was also IRI significantly higher in those who did not experience IRI than those who did in the follow-up period (0.845 vs. 0.301, P=0.024). These data suggest that telomerase expression may correlate with immune capacity for vaccine response in the elderly and could represent a target for recognizing risk for vaccine failure.
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Affiliation(s)
- P V Targonski
- Mayo Vaccine Research Group, Rochester, Minnesota, USA.
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117
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Iancu EM, Speiser DE, Rufer N. Assessing ageing of individual T lymphocytes: mission impossible? Mech Ageing Dev 2007; 129:67-78. [PMID: 18048082 DOI: 10.1016/j.mad.2007.10.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Revised: 10/15/2007] [Accepted: 10/23/2007] [Indexed: 12/22/2022]
Abstract
Effector T lymphocytes are the progeny of a limited number of antigen-specific precursor cells and it has been estimated that clonotypic human T cells may expand million fold on their way reaching high cell numbers that are sufficient for immune protection. Moreover, memory T cell responses are characterized by repetitive expansion of antigen-specific T cell clonotypes, and limitations in the proliferative capacity could lead to immune senescence. Because telomeres progressively shorten as a function of cell division, telomere length is a powerful indicator of the replicative in vivo history of human T lymphocytes. In this review, we summarize observations made over the last decade on telomere length dynamics of well-defined T cell populations derived from healthy donors and patients with infectious disease or cancer. We focus on T cell differentiation, T cell ageing, and natural and vaccine induced immune responses. We also discuss the scientific evidence for in vivo replicative senescence of antigen-specific T cells, and evaluate the available methods for measuring telomere lengths and telomerase activity, and their potential and limitations to increase our understanding of T cell physiology.
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Affiliation(s)
- Emanuela M Iancu
- Division of Experimental Oncology, Multidisciplinary Oncology Center CePO, Avenue Pierre-Decker 4, CH-1005 Lausanne, Switzerland
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118
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Zimmermann S, Martens UM. Telomeres, senescence, and hematopoietic stem cells. Cell Tissue Res 2007; 331:79-90. [PMID: 17960423 DOI: 10.1007/s00441-007-0469-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2007] [Accepted: 07/10/2007] [Indexed: 01/01/2023]
Abstract
The replicative lifespan of normal somatic cells is restricted by the erosion of telomeres, which are protective caps at the ends of linear chromosomes. The loss of telomeres induces antiproliferative signals that eventually lead to cellular senescence. The enzyme complex telomerase can maintain telomeres, but its expression is confined to highly proliferative cells such as stem cells and tumor cells. The immense regenerative capacity of the hematopoietic system is provided by a distinct type of adult stem cell: hematopoietic stem cells (HSCs). Although blood cells have to be produced continuously throughout life, the HSC pool seems not to be spared by aging processes. Indeed, limited expression of telomerase is not sufficient to prevent telomere shortening in these cells, which is thought ultimately to limit their proliferative capacity. In this review, we discuss the relevance of telomere maintenance for the hematopoietic stem cell compartment and consider potential functions of telomerase in this context. We also present possible clinical applications of telomere manipulation in HSCs and new insights affecting the aging of the hematopoietic stem cell pool and replicative exhaustion.
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Affiliation(s)
- Stefan Zimmermann
- Department of Hematology/Oncology, Freiburg University Medical Center, Hugstetterstrasse 55, 79106, Freiburg, Germany.
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119
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Kurosaka D, Yasuda J, Ikeshima-Kataoka H, Ozawa Y, Yoshida K, Yasuda C, Kingetsu I, Saito S, Yamada A. Decreased numbers of signal-joint T cell receptor excision circle-containing CD4+ and CD8+ cells in systemic lupus erythematosus patients. Mod Rheumatol 2007; 17:296-300. [PMID: 17694262 DOI: 10.1007/s10165-007-0583-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2006] [Accepted: 03/06/2007] [Indexed: 11/25/2022]
Abstract
Systemic lupus erythematosus (SLE) patients have a decreased number of peripheral blood T cells containing signal-joint T cell receptor excision circles (Sj TRECs), which are considered an indicator of thymic output. The objective of this study was to investigate the mechanism of the decrease in such T cells. Peripheral blood T cells from SLE patients were classified into CD4+ and CD8+ cells. Sj TREC levels were measured by real-time PCR. Telomerase activity was determined by the telomeric repeat amplification protocol assay. The numbers of Sj TREC containing CD4+ and CD8+ cells were lower in the peripheral blood of SLE patients than in the controls. A correlation was found between the numbers of Sj TREC-positive CD4+ and CD8+ cells. The level of TRECs is influenced by an increase in cell division. To examine this increase, telomerase activity as an indicator of cell division was measured simultaneously; however, there was no correlation between the Sj TREC level and telomerase activity. These results suggest that decreased thymic output occurs in SLE patients.
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Affiliation(s)
- Daitaro Kurosaka
- Division of Rhuematology, Department of Internal Medicine, Jikei University School of Medicine, 3-25-8 Nishishinbashi, Minato-ku, Tokyo, 105-8461, Japan.
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120
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Khair G, Monson JRT, Greenman J. Epithelial molecular markers in the peripheral blood of patients with colorectal cancer. Dis Colon Rectum 2007; 50:1188-203. [PMID: 17436048 DOI: 10.1007/s10350-006-0875-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Despite the modest improvements in patient survival from colorectal cancer in the last few decades, the overall five-year survival rate remains at 40 to 45 percent. Surgical resection is the mainstay of treatment for colorectal cancer; however, nearly one-half of all patients who undergo a potentially curative resection will relapse because of undetected micrometastasis. The fact that the overall survival rate remains poor strongly suggests that the dissemination of these cells occurs early in the disease process and emphasizes the need for finding feasible diagnostic methods with sufficient sensitivity and specificity. The most commonly used technique for the detection of nucleic acid material of disseminated tumor cells is the polymerase chain reaction. We critically review the literature on DNA and messenger ribonucleic acid molecular markers that have been used for the detection of circulating tumor cells in the peripheral blood of patients with colorectal cancer and other solid tumors as appropriate for comparison. The cytokeratins, particularly cytokeratin 19 and cytokeratin 20, are the most investigated prognostic markers, but even for these questions remain about their clinical value, and hence most recent studies are utilizing a combination of factors. There is an urgent need for standardized isolation and analysis techniques to be adopted thus allowing large-scale, appropriately controlled, multicenter trials to be undertaken on the most promising candidate markers.
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Affiliation(s)
- Ghaith Khair
- Cancer Division, Postgraduate Medical Institute, University of Hull, Kingston-upon-Hull, UK
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121
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Plunkett FJ, Franzese O, Finney HM, Fletcher JM, Belaramani LL, Salmon M, Dokal I, Webster D, Lawson ADG, Akbar AN. The loss of telomerase activity in highly differentiated CD8+CD28-CD27- T cells is associated with decreased Akt (Ser473) phosphorylation. THE JOURNAL OF IMMUNOLOGY 2007; 178:7710-9. [PMID: 17548608 DOI: 10.4049/jimmunol.178.12.7710] [Citation(s) in RCA: 152] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The enzyme telomerase is essential for maintaining the replicative capacity of memory T cells. Although CD28 costimulatory signals can up-regulate telomerase activity, human CD8(+) T cells lose CD28 expression after repeated activation. Nevertheless, telomerase is still inducible in CD8(+)CD28(-) T cells. To identify alternative costimulatory pathways that may be involved, we introduced chimeric receptors containing the signaling domains of CD28, CD27, CD137, CD134, and ICOS in series with the CD3 zeta (zeta) chain into primary human CD8(+) T cells. Although CD3 zeta-chain signals alone were ineffective, triggering of all the other constructs induced proliferation and telomerase activity. However, not all CD8(+)CD28(-) T cells could up-regulate this enzyme. The further fractionation of CD8(+)CD28(-) T cells into CD8(+)CD28(-) CD27(+) and CD8(+)CD28(-)CD27(-) subsets showed that the latter had significantly shorter telomeres and extremely poor telomerase activity. The restoration of CD28 signaling in CD8(+)CD28(-)CD27(-) T cells could not reverse the low telomerase activity that was not due to decreased expression of human telomerase reverse transcriptase, the enzyme catalytic subunit. Instead, the defect was associated with decreased phosphorylation of the kinase Akt, that phosphorylates human telomerase reverse transcriptase to induce telomerase activity. Furthermore, the defective Akt phosphorylation in these cells was specific for the Ser(473) but not the Thr(308) phosphorylation site of this molecule. Telomerase down-regulation in highly differentiated CD8(+)CD28(-)CD27(-) T cells marks their inexorable progress toward a replicative end stage after activation. This limits the ability of memory CD8(+) T cells to be maintained by continuous proliferation in vivo.
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Affiliation(s)
- Fiona J Plunkett
- Department of Immunology and Molecular Pathology, University College London, 46 Cleveland Street, London, United Kingdom
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122
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Akbar AN, Vukmanovic-Stejic M. Telomerase in T lymphocytes: use it and lose it? THE JOURNAL OF IMMUNOLOGY 2007; 178:6689-94. [PMID: 17513711 DOI: 10.4049/jimmunol.178.11.6689] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The enzyme telomerase counteracts telomere loss in proliferating cells and extends their capacity for replication. The importance of telomerase is highlighted by the award of the 2006 Albert Lasker Prize for Basic Medical Research for its discovery. Malignant cells subvert telomerase induction to their advantage, and up-regulation of this enzyme confers these populations with unlimited proliferative potential with obvious detrimental consequences. However this enzyme is also essential for the lifelong maintenance of normal cell populations that have a high rate of turnover. Thymic involution in early adulthood dictates that memory T cell populations have to be maintained by continuous proliferation. This highlights the inherent paradox that telomerase down-regulation in T cells may protect against malignancy yet also lead to replicative exhaustion of repeatedly activated memory T cells. In this article, we review the data on telomerase regulation in T lymphocytes and the implications this has for the maintenance of T cell memory.
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Affiliation(s)
- Arne N Akbar
- Department of Immunology and Molecular Pathology, University College London, London, United Kingdom
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123
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Drummond MW, Balabanov S, Holyoake TL, Brummendorf TH. Concise review: Telomere biology in normal and leukemic hematopoietic stem cells. Stem Cells 2007; 25:1853-61. [PMID: 17510216 DOI: 10.1634/stemcells.2007-0057] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The measurement of telomere length can give an insight into the replicative history of the cells in question. Much of the observed telomere loss occurs at the stem and progenitor cell level, even though these populations express the enzyme telomerase. Telomerase-transfected hematopoietic stem cells (HSC), although able to maintain telomere length, are still limited in terms of ability to undergo sequential transplantation, and other factors require to be addressed to achieve optimal levels of stem cell expansion. Unchecked telomere loss by HSC, meanwhile, would appear to play a significant role in the pathogenesis of bone marrow failure, as observed in the condition dyskeratosis congenita. This heterogeneous inherited condition appears to exhibit telomerase dysfunction as a common final pathogenic mechanism. Although less well-established for acquired marrow failure syndromes, mutations in key telomerase components have been described. The identification of the leukemic stem cell (LSC), along with the desire to target this population with anti-leukemia therapy, demands that telomerase biology be fully understood in this cell compartment. Future studies using primary selected LSC-rich samples are required. A better understanding of telomerase regulation in this population may allow effective targeting of the telomerase enzyme complex using small molecule inhibitors or additional novel approaches. Disclosure of potential conflicts of interest is found at the end of this article.
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MESH Headings
- Acute Disease
- Animals
- Cell Proliferation
- DNA Replication/physiology
- DNA, Neoplasm/physiology
- Hematopoietic Stem Cell Transplantation
- Hematopoietic Stem Cells/enzymology
- Hematopoietic Stem Cells/pathology
- Hematopoietic Stem Cells/physiology
- Humans
- Leukemia/enzymology
- Leukemia/genetics
- Leukemia/pathology
- Leukemia/physiopathology
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/enzymology
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/genetics
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/physiopathology
- Leukemia, Myeloid/enzymology
- Leukemia, Myeloid/genetics
- Leukemia, Myeloid/physiopathology
- Mice
- Mice, Knockout
- Models, Biological
- Neural Tube Defects/enzymology
- Neural Tube Defects/genetics
- Neural Tube Defects/physiopathology
- Telomerase/genetics
- Telomerase/metabolism
- Telomerase/physiology
- Telomere/metabolism
- Telomere/physiology
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124
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Kurosaka D. [Abnormalities in lymphocyte telomerase activity and telomere length in systemic lupus erythematosus]. ACTA ACUST UNITED AC 2007; 30:29-36. [PMID: 17332702 DOI: 10.2177/jsci.30.29] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
T-cell telomerase activity was high in the active and inactive stages of systemic lupus erythematosus (SLE). In contrast, B-cell telomerase activity was very high only in the active stage. Compared with normal subjects, SLE patients had a shorter T-cell telomere, but their B-cell telomere length did not differ from that of normal subjects. These findings suggest that T cells are always activated, and that the manifestation of the disease requires the activation of not only T but also B cells. B-cell inhibition alone may be sufficient to suppress the clinical symptoms of SLE, but we consider that the essential treatment of SLE should target T cells as well. In recent years, various biologicals have begun to be used for the treatment of SLE. It is interesting how the use of such biologicals in the future will change T- and B-cell telomerase activity. In formulating a therapeutic strategy using biologicals for SLE, the measurement of telomerase activity in T and B cells seems useful for the preparation of target cells, selection of therapeutic drugs, and evaluation of therapeutic responses.
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Affiliation(s)
- Daitaro Kurosaka
- Division of Rheumatology, Department of Internal Medicine, Jikei University School of Medicine
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125
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Hsu C, Jones SA, Cohen CJ, Zheng Z, Kerstann K, Zhou J, Robbins PF, Peng PD, Shen X, Gomes TJ, Dunbar CE, Munroe DJ, Stewart C, Cornetta K, Wangsa D, Ried T, Rosenberg SA, Morgan RA. Cytokine-independent growth and clonal expansion of a primary human CD8+ T-cell clone following retroviral transduction with the IL-15 gene. Blood 2007; 109:5168-77. [PMID: 17353346 PMCID: PMC1890824 DOI: 10.1182/blood-2006-06-029173] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Malignancies arising from retrovirally transduced hematopoietic stem cells have been reported in animal models and human gene therapy trials. Whether mature lymphocytes are susceptible to insertional mutagenesis is unknown. We have characterized a primary human CD8(+) T-cell clone, which exhibited logarithmic ex vivo growth in the absence of exogenous cytokine support for more than 1 year after transduction with a murine leukemia virus-based vector encoding the T-cell growth factor IL-15. Phenotypically, the clone was CD28(-), CD45RA(-), CD45RO(+), and CD62L(-), a profile consistent with effector memory T lymphocytes. After gene transfer with tumor-antigen-specific T-cell receptors, the clone secreted IFN-gamma upon encountering tumor targets, providing further evidence that they derived from mature lymphocytes. Gene-expression analyses revealed no evidence of insertional activation of genes flanking the retroviral insertion sites. The clone exhibited constitutive telomerase activity, and the presence of autocrine loop was suggested by impaired cell proliferation following knockdown of IL-15R alpha expression. The generation of this cell line suggests that nonphysiologic expression of IL-15 can result in the long-term in vitro growth of mature human T lymphocytes. The cytokine-independent growth of this line was a rare event that has not been observed in other IL-15 vector transduction experiments or with any other integrating vector system. It does not appear that the retroviral vector integration sites played a role in the continuous growth of this cell clone, but this remains under investigation.
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Affiliation(s)
- Cary Hsu
- Surgery Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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126
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Cortez-Gonzalez X, Zanetti M. Telomerase immunity from bench to bedside: round one. J Transl Med 2007; 5:12. [PMID: 17324292 PMCID: PMC1839079 DOI: 10.1186/1479-5876-5-12] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2006] [Accepted: 02/26/2007] [Indexed: 11/10/2022] Open
Abstract
Telomerase, a reverse transcriptase primarily devoted to the elongation of telomeres in mammalian cells, is also the first bona fide common tumor antigen. In fact, telomerase is over-expressed in > 85% of tumor cells irrespective of origin and histological type. In the past seven years, there has been considerable interest in assessing telomerase as substrate for vaccination in cancer patients to induce CD8 T cell responses. Because the activation of T cells is restricted by the MHC molecules on antigen presenting cells or tumor cells, the identification of telomerase peptides immunogenic for humans is tightly linked with HLA types. To date, a handful of peptides have been identified through a variety of screening procedures, including bioinformatics prediction, in vivo immunization of HLA transgenic mice, in vitro immunization of PBMC from normal donors and cancer patients, and processing in human tumor cells. Currently, there exist putative peptides for five major HLA types (A2, A1, A3, A24 and B7). Due to the complexity of the HLA system, trials have been performed focusing on the most prevalent HLA type, HLA-A2. Here, we summarize this collective effort and highlight results obtained in Phase 1 trials including a Phase 1 trial performed at the UCSD Cancer Center.
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Affiliation(s)
- Xochtil Cortez-Gonzalez
- The Laboratory of Immunology, Department of Medicine and Moores Cancer Center, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0837, USA.
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127
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Thomas-Kaskel AK, Portugal TGA, Herchenbach D, Houet L, Veelken H, Finke J. Allogeneic HLA-matched donor dendritic cells loaded with patient leukemic blasts preferentially induce CD4-positive leukemia-reactive donor lymphocytes. Acta Haematol 2007; 117:226-35. [PMID: 17308369 DOI: 10.1159/000099547] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2006] [Accepted: 11/14/2006] [Indexed: 11/19/2022]
Abstract
BACKGROUND The therapeutic value of donor lymphocyte infusions in patients who relapse with acute myeloid leukemia (AML) after allogeneic hematopoietic stem cell transplantation (HSCT) is limited by a low efficacy and the risk of graft-versus-host disease. We aimed at generating leukemia-reactive donor T cells for patients with AML. METHODS Peripheral blood mononuclear cells of the donor were stimulated with mature donor dendritic cells, pulsed with irradiated patient leukemic blasts (LB), or directly with cytokine-treated LB. After 3 weekly stimulations, donor cells were tested for anti-leukemic reactivity in an IFNgamma Elispot. RESULTS In 5 of 6 donors, cells with reactivity against patient LB with low or absent reactivity against non-leukemic cells could be generated. T cell subset analyses in 2 donors indicated that specific anti-leukemic reactivity was mainly mediated by CD4+ T cells, which were also the predominant cell fraction in 4 of 6 donors. One leukemia-reactive donor T cell line was expanded with a recently developed system. One week of expansion resulted in a 10-fold increase in reactivity with sustained specificity of the resulting T cell line. CONCLUSIONS Our results show the feasibility of the in vitro generation of leukemia-reactive donor lymphocytes, rendering this method a promising tool for post-HSCT immunotherapy.
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Affiliation(s)
- Anna-Katharina Thomas-Kaskel
- Department of Internal Medicine I, Hematology and Oncology, Freiburg University Medical Center, Freiburg, Germany.
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128
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Targonski PV, Jacobson RM, Poland GA. Immunosenescence: role and measurement in influenza vaccine response among the elderly. Vaccine 2007; 25:3066-9. [PMID: 17275144 DOI: 10.1016/j.vaccine.2007.01.025] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Immunosenescence refers to the inability of an aging immune system to produce an appropriate and effective response to challenge. This immune dysfunction may manifest as increased susceptibility to infection, cancer, autoimmune disease, and vaccine failure. Mounting biological evidence supports the potential clinical relevance and impact of immunosenenscence. We briefly review immunosenescence with a focus on replicative senescence in cytotoxic T cells and recent clinical studies examining its association with influenza and infectious disease outcomes.
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Affiliation(s)
- Paul V Targonski
- Vaccine Research Group, Mayo Clinic, 200 First Street Southwest, Rochester, MN 55905-0001, United States.
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129
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Shen X, Zhou J, Hathcock KS, Robbins P, Powell DJ, Rosenberg SA, Hodes RJ. Persistence of tumor infiltrating lymphocytes in adoptive immunotherapy correlates with telomere length. J Immunother 2007; 30:123-9. [PMID: 17198091 PMCID: PMC2151201 DOI: 10.1097/01.cji.0000211321.07654.b8] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Transfer of autologous tumor-specific tumor infiltrating lymphocytes (TILs) in adoptive immunotherapy can mediate the regression of tumor in patients with metastatic melanoma. In this procedure, TILs from resected tumors are expanded in vitro, then administered to patients and further stimulated to proliferate in vivo by the administration of high dose IL-2. After in vitro expansion, TILs are often dominated by a few specific clonotypes, and recently it was reported that the persistence in vivo of one or more of these clonotypes correlated with positive therapeutic response. We and others have previously shown that repeated in vitro stimulation and clonal expansion of normal human T lymphocytes results in progressive decrease in telomerase activity and shortening of telomeres, ultimately resulting in replicative senescence. In the studies reported here, we therefore compared telomerase activity and telomere length in persistent and nonpersistent TIL clonotypes before transfer in vivo, and found a correlation between telomere length and clonal persistence. We also observed that TILs proliferate extensively in vivo in the days after transfer, but fail to induce substantial telomerase activity, and undergo rapid decreases in telomere length within days after transfer. Thus, in vivo loss of telomeres by clonotypes that have the shortest telomeres at the time of administration may drive these clones to replicative senescence, whereas cells with longer telomeres are able to persist and mediate antitumor effects. These findings are relevant both to predicting effectiveness of adoptive immunotherapy and in deriving strategies for improving effectiveness by sustaining telomere length.
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Affiliation(s)
- Xinglei Shen
- Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Juhua Zhou
- Surgery Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Karen S. Hathcock
- Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Paul Robbins
- Surgery Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Daniel J. Powell
- Surgery Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Steven A. Rosenberg
- Surgery Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Richard J. Hodes
- Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
- National Institute on Aging, National Institutes of Health, Bethesda, MD 20892
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130
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Röth A, Schneider L, Himmelreich H, Baerlocher GM, Dührsen U. Impact of culture conditions on the proliferative lifespan of human T cells in vitro. Cytotherapy 2007; 9:91-8. [PMID: 17354104 DOI: 10.1080/14653240601113197] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
BACKGROUND In human T cells, telomerase is transiently expressed upon activation and stimulation and, as shown previously, telomerase levels are able to control the lifespan of T cells. To improve T-cell expansion it is of critical importance to understand the effects of culture parameters on telomerase activity and lifespan. METHODS We investigated the influence of culture condition (FCS, human AB serum and autologous serum) and stimulation (PHA/feeder cells, anti-CD3/CD28 beads) on the lifespan, clonogenicity (number of positive wells), cell cycle, telomerase activity and telomere length of T cells in vitro. RESULTS The proliferative lifespan of T cells expanded with PHA/feeder cells and autologous serum from different donors was doubled compared with stimulation with PHA/feeder cells and AB serum. No or only a small difference was found for T cells expanded with anti-CD3/CD28 beads and autologous or AB serum. The use of autologous serum also increased the clonogenicity to about three-fold compared with the use of AB serum or FCS, without any signs of differences in the fractions of cycling cells. Interestingly, T cells cultured with autologous serum exhibited a significantly higher telomerase activity at day 6 after stimulation and a reduced decline of telomerase activity compared with cultures with AB serum. DISCUSSION The use of autologous serum combined with PHA stimulation and feeder cells remarkably extends the proliferative lifespan and clonogenicity and increases the telomerase activity of human T cells in vitro. This might be useful for applications where large numbers of specific T cells are required.
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Affiliation(s)
- A Röth
- Department of Hematology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
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131
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Sheng WY, Chen YR, Wang TCV. A major role of PKC theta and NFkappaB in the regulation of hTERT in human T lymphocytes. FEBS Lett 2006; 580:6819-24. [PMID: 17141225 DOI: 10.1016/j.febslet.2006.11.044] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2006] [Revised: 11/13/2006] [Accepted: 11/16/2006] [Indexed: 10/23/2022]
Abstract
Expression of the telomerase catalytic subunit (TERT) is the rate-limiting determinant of telomerase activity in most human cells. In this work, we examined the participation of protein kinase C (PKC) in the regulation of hTERT expression in human T lymphocytes. Transient expression assays using luciferase reporter plasmids containing hTERT promoter showed that overexpression of PKC theta, but not the other PKC isoforms, could activate the promoter activity of hTERT in resting T lymphocytes. Among the PKC theta-activated signalings, we presented evidence that the expression of hTERT is mediated through NFkappaB but not through MEK or c-Jun N-terminal kinase pathways. Analysis of the hTERT promoter occupancy in vivo using chromatin immunoprecipitation assays, however, did not detect an increased binding of NFkappaB to the hTERT promoter in the activated T cells, although an increased binding of cMyc and Sp1 was detected. Together with the observation that inhibition of NFkappaB eliminated the induction of cMyc in activated T cells, these results suggest that PKC theta-activated NFkappaB signaling regulates the expression of hTERT via cMyc in human T lymphocytes.
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Affiliation(s)
- Wei-Yun Sheng
- Department of Molecular and Cellular Biology, Chang Gung University, Kwei-San, Tao-Yuan 333, Taiwan
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132
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Batinac T, Zamolo G, Hadzisejdic I. Telomerase in anti-tumor response. Med Hypotheses 2006; 68:128-30. [PMID: 16935436 DOI: 10.1016/j.mehy.2006.07.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2006] [Accepted: 06/12/2006] [Indexed: 11/17/2022]
Abstract
Telomerase is responsible for maintaining the length of telomeres at the end of chromosomes. It protects chromosomes from degradation and aberrant recombination during replication prolonging the life span of the cell. Human telomerase reverse transcriptase (hTERT) is highly expressed in >85% of cancer cells but its expression is repressed in most human somatic cells. It has been shown that expression of human telomerase reverse transcriptase greatly extends the life span of both human CD8+ and CD4+ T cells during activation and proliferation. hTERT-positive tumor cells can induce cytotoxic T lymphocyte response as well as T helper response. On the other hand, it is possible that cytotoxic immune response to hTERT-positive tumor cells can cause autoimmune reaction directed against T cells in a tumor bearing host. This could lead to apoptosis and decreased number of activated T cells and insufficient anti-tumor immunity resulting in tumor progression.
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Affiliation(s)
- Tanja Batinac
- Department of Dermatovenerology, Rijeka University Hospital, Kresimirova 42, 51000 Rijeka, Croatia
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133
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Miyoshi T, Hirohata S, Ogawa H, Doi M, Obika M, Yonezawa T, Sado Y, Kusachi S, Kyo S, Kondo S, Shiratori Y, Hudson BG, Ninomiya Y. Tumor-specific expression of the RGD-alpha3(IV)NC1 domain suppresses endothelial tube formation and tumor growth in mice. FASEB J 2006; 20:1904-6. [PMID: 16877525 DOI: 10.1096/fj.05-5565fje] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Angiogenesis plays an essential role in tumor growth. This study investigated expression of the noncollagenous domain of alpha3(IV) collagen (alpha3(IV)NC1) transduced into tumors and its inhibition of tumor growth. We hypothesized that if a human telomerase reverse transcriptase (hTERT) promoter-driven RGD motif containing alpha3(IV)NC1 (hTERT/RGD-alpha3(IV)NC1) were expressed in telomerase-expressing tumor cells, it would inhibit tumor growth by its anti-angiogenic property. Adenoviral transduction of hTERT/RGD-alpha3(IV)NC1 expressed RGD-alpha3(IV)NC1 in hTERT-positive tumor cell lines. However, hTERT/RGD-alpha3(IV)NC1 did not express RGD-alpha3(IV)NC1 in hTERT-negative cells such as keratinocytes and fibroblasts. The secreted RGD-alpha3(IV)NC1 in the conditioned medium from tumor cells inhibited cell proliferation as well as tube formation in cultured endothelial cells, but had no effect on other types of cells. In an in vivo model, adenoviral hTERT/RGD-alpha3(IV)NC1 gene therapy showed limited expression of RGD-alpha3(IV)NC1 in tumors and resulted in a significant decrease of vessel density in tumors. The growth of subcutaneous (s.c.) tumors in nude mice was significantly suppressed by treatment with hTERT/RGD-alpha3(IV)NC1. In addition, long-term inhibition of tumor growth was achieved by intermittent administration of hTERT/RGD-alpha3(IV)NC1. In conclusion, our findings demonstrate that tumor-specific anti-angiogenic gene therapy utilizing RGD-alpha3(IV)NC1 under the hTERT promoter inhibited angiogenesis in tumors, resulting in an antitumor effect.
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Affiliation(s)
- Toru Miyoshi
- Department of Medicine and Medical Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Japan
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134
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Trapp S, Parcells MS, Kamil JP, Schumacher D, Tischer BK, Kumar PM, Nair VK, Osterrieder N. A virus-encoded telomerase RNA promotes malignant T cell lymphomagenesis. ACTA ACUST UNITED AC 2006; 203:1307-17. [PMID: 16651385 PMCID: PMC2121211 DOI: 10.1084/jem.20052240] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Telomerase is a ribonucleoprotein complex consisting of two essential core components: a reverse transcriptase and an RNA subunit (telomerase RNA [TR]). Dysregulation of telomerase has been associated with cell immortalization and oncogenesis. Marek's disease herpesvirus (MDV) induces a malignant T cell lymphoma in chickens and harbors in its genome two identical copies of a viral TR (vTR) with 88% sequence identity to chicken TR. MDV mutants lacking both copies of vTR were significantly impaired in their ability to induce T cell lymphomas, although lytic replication in vivo was unaffected. Tumor incidences were reduced by >60% in chickens infected with vTR− viruses compared with animals inoculated with MDV harboring at least one intact copy of vTR. Lymphomas in animals infected with the vTR− viruses were also significantly smaller in size and less disseminated. Constitutive expression of vTR in the chicken fibroblast cell line DF-1 resulted in a phenotype consistent with transformation as indicated by morphological alteration, enhanced anchorage-independent cell growth, cell growth beyond saturation density, and increased expression levels of integrin αv. We concluded that vTR plays a critical role in MDV-induced T cell lymphomagenesis. Furthermore, our results provide the first description of tumor-promoting effects of TR in a natural virus–host infection model.
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Affiliation(s)
- Sascha Trapp
- Department of Microbiology and Immunology, Cornell University, Ithaca, NY 14853, USA
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135
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Ram R, Uziel O, Lahav M. The importance of the telomere and telomerase system in hematological malignancies. Leuk Lymphoma 2006; 46:1121-35. [PMID: 16085552 DOI: 10.1080/10428190500125853] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Telomeres are specialized chromosomal end structures composed of repeat TTAGGG sequences in humans. They shorten with each cell division and thus serve as the "mitotic clock" of the cell. One of their main functions is the maintenance of chromosomal integrity and their excessive shortening is associated with DNA instability. Telomerase, a unique reverse transcriptase, is inactive in most somatic human cells and is up-regulated in most cancer cells. Recently, the biology of the telomere/telomerase system has attracted much attention because of its possible role in carcinogenesis and aging. In this article we review the biology of this system and its relevance to normal and malignant hematopoietic cells. The biological, diagnostic and prognostic value of telomere/telomerase biology is discussed, as well as its potential future applications in cancer therapeutics.
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Affiliation(s)
- Ron Ram
- Department of Medicine A, Rabin medical Center, Beilinson Campus, Petah-Tikva, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
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136
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Zhou J, Shen X, Huang J, Hodes RJ, Rosenberg SA, Robbins PF. Telomere length of transferred lymphocytes correlates with in vivo persistence and tumor regression in melanoma patients receiving cell transfer therapy. THE JOURNAL OF IMMUNOLOGY 2006; 175:7046-52. [PMID: 16272366 PMCID: PMC1351312 DOI: 10.4049/jimmunol.175.10.7046] [Citation(s) in RCA: 252] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Recent studies have indicated that adoptive immunotherapy with autologous antitumor tumor-infiltrating lymphocytes (TILs) following nonmyeloablative chemotherapy mediates tumor regression in approximately 50% of treated patients with metastatic melanoma, and that tumor regression is correlated with the degree of persistence of adoptively transferred T cells in peripheral blood. These findings, which suggested that the proliferative potential of transferred T cells may play a role in clinical responses, led to the current studies in which telomere length as well as phenotypic markers expressed on the administered TILs were examined. TILs that were associated with objective clinical responses following adoptive transfer possessed a mean telomere length of 6.3 kb, whereas TILs that were not associated with significant clinical responses were significantly shorter, averaging 4.9 kb (p < 0.01). Furthermore, individual TIL-derived T cell clonotypes that persisted in vivo following adoptive cell transfer possessed telomeres that were longer than telomeres of T cell clonotypes that failed to persist (6.2 vs 4.5 kb, respectively; p < 0.001). Expression of the costimulatory molecule CD28 also appeared to be associated with long telomeres and T cell persistence. These results, indicating that the telomere length of transferred lymphocytes correlated with in vivo T cell persistence following adoptive transfer, and coupled with the previous observation that T cell persistence was associated with clinical responses in this adoptive immunotherapy trial, suggest that telomere length and the proliferative potential of the transferred T cells may play a significant role in mediating response to adoptive immunotherapy.
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Affiliation(s)
- Juhua Zhou
- Surgery Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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137
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Marrone A, Walne A, Dokal I. Dyskeratosis congenita: telomerase, telomeres and anticipation. Curr Opin Genet Dev 2005; 15:249-57. [PMID: 15917199 DOI: 10.1016/j.gde.2005.04.004] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2004] [Accepted: 04/06/2005] [Indexed: 01/07/2023]
Abstract
Dyskeratosis congenita (DC) is a rare bone marrow failure syndrome that displays marked clinical and genetic heterogeneity. The identification of dyskeratosis congenita gene 1 (DKC1) mutations in X-linked recessive patients initially suggested that DC is a defective pseudouridylation disorder. The subsequent identification of mutations in the telomerase RNA component (TERC) of autosomal dominant DC patients together with the discovery that both TERC and the DKC1-encoded protein, dyskerin, are closely associated in the telomerase complex have suggested that the pathophysiology of DC predominantly relates to defective telomere maintenance. Recent discoveries have shown that autosomal dominant DC exhibits disease anticipation and that this is associated with progressive telomere shortening owing to the haplo-insufficiency of TERC.
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Affiliation(s)
- Anna Marrone
- Department of Haematology, Imperial College London, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK.
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138
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Faraoni I, Cottarelli A, Giuliani A, Bonmassar L, Rossi L, Bonmassar E. A novel telomerase-based approach to detect natural cell-mediated cytotoxic activity against tumor cells in vitro. J Immunol Methods 2005; 305:162-72. [PMID: 16165149 DOI: 10.1016/j.jim.2005.07.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2005] [Revised: 07/01/2005] [Accepted: 07/07/2005] [Indexed: 11/16/2022]
Abstract
This study was designed to develop a novel technical approach based on tumor-associated telomerase activity to detect cytotoxic activity of effector cells of the natural immune system against neoplastic cells. Human K562, DAUDI or Raji leukemia cells were co-cultured with NK or LAK effector cells at 37 degrees C for 4 h. Target cell killing was evaluated by 51Cr-release assay (CRA) or reduction of telomerase activity (R-TRAPCTX) of the target after exposure to effector cells. NK and LAK effector cells tested against K562 target cells at effector/target ratio of 50:1 showed cytotoxicity of 65% and 78%, respectively, with CRA and 51% and 74%, respectively, with R-TRAPCTX. Incorrect results were obtained with CRA when target cells were admixed with normal fibroblasts, whereas R-TRAPCTX was not influenced by the presence of normal cells. Control experiments performed with telomerase-negative cells showed that telomerase activity of effector cells was not altered during the cytolytic reaction. Moreover, supernatants obtained from effector-target cell co-cultures did not influence telomerase activity of targets. This novel R-TRAPCTX method to assay anti-tumor natural and possibly antigen-dependent cell-mediated cytotoxicity appears to provide sensible advantages over classical CRA or gamma-interferon release by effector cells in presence of target cells (ELISPOT), since (a) it furnishes reliable data on effector cell killing against neoplastic cells, even when malignant cells are admixed with normal cells, as frequently occurs in tumor biopsies, not manageable with CRA; (b) it provides an actual measure of target cell killing, not furnished by ELISPOT technique.
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Affiliation(s)
- Isabella Faraoni
- Department of Neuroscience, University of Rome Tor Vergata, Via Montpellier 1, 00133 Rome, Italy.
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139
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Satra M, Dalekos GN, Kollia P, Vamvakopoulos N, Tsezou A. Telomerase reverse transcriptase mRNA expression in peripheral lymphocytes of patients with chronic HBV and HCV infections. J Viral Hepat 2005; 12:488-93. [PMID: 16108763 DOI: 10.1111/j.1365-2893.2005.00550.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Telomerase activity is present at low levels in peripheral lymphocytes (PL) and is upregulated upon activation, possibly protecting PL from telomere shortening. As decreased telomere length is considered a sign of cellular senescence, telomerase may, therefore, play an important role on immune function, organ regeneration and carcinogenesis. So far, quantification of human telomerase reverse transcriptase levels (hTERT) in PL, has not been reported. We determined hTERT mRNA levels in PL of hepatitis B virus (HBV) and hepatitis C virus (HCV) patients, in an attempt to address whether hTERT transcripts in PL are altered in these viral diseases, which are characterized by immune dysfunction and increased incidence of hepatocarcinogenesis. hTERT mRNA levels in PL of HBV (n = 17), HCV (n = 24) patients and healthy controls (n = 22) were quantified by real-time polymerase chain reaction. We observed significantly lower hTERT mRNA levels in HBV and HCV patients compared with healthy individuals (P < 0.05). hTERT mRNA levels were not associated with the patients' clinical status (inactive, hepatitis and cirrhosis). Also no correlation was observed between hTERT mRNA expression, and HBV and HCV replicative activity. In the inactive group (n = 18) we observed a negative correlation between hTERT mRNA expression and disease duration (rs = -0.52, P < 0.03). We performed for the first time an accurate quantification of hTERT mRNA expression in PL of HBV and HCV patients. The observed low levels of hTERT mRNA expression in the above patients may suggest its involvement in the immunopathogenesis of chronic viral hepatitis.
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Affiliation(s)
- M Satra
- Department of Biology, Academic Liver Unit, Medical School, University of Thessaly, Larissa, Greece
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140
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Long S, Argyle DJ, Gault EA, Campbell S, Nasir L. The canine telomerase catalytic subunit (dogTERT): Characterisation of the gene promoter and identification of proximal core sequences necessary for specific transcriptional activity in canine telomerase positive cell lines. Gene 2005; 358:111-20. [PMID: 16051448 DOI: 10.1016/j.gene.2005.05.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2005] [Revised: 04/08/2005] [Accepted: 04/14/2005] [Indexed: 11/20/2022]
Abstract
Telomerase biology is complicated by studies that show that telomere expression and telomere biology differs between species, and that existing animal models do not closely resemble the human situation. We have previously reported a description of telomere/telomerase biology in the dog and have suggested this as an alternative model system. To further elucidate telomerase biology in this species we have cloned and characterised the canine reverse transcriptase (dogTERT) promoter. We demonstrate that core promoter activity is contained within a region extending approximately 300 bp upstream of the ATG codon. Transient transfections in telomerase-positive canine cell lines and telomerase negative fibroblasts showed that the promoter is only active in telomerase positive cell lines. Sequence analysis demonstrated that the 5' regulatory region is GC-rich and contains no TATA or CAAT box, similar to the human TERT promoter. Motif searches revealed the presence of multiple transcription factor binding sites common to both the human and canine TERT promoters, including a single E-box, Sp1, AP1, MZF-2 and ER/Sp1 binding sites. These findings suggest that the dogTERT gene shares similar transcriptional control to hTERT. Identification of the core promoter necessary for activity may allow the use of naturally occurring cancers in dogs as a preclinical testing ground for telomerase targeted therapies in human cancer patients.
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Affiliation(s)
- S Long
- Division of Pathological Sciences, Institute of Comparative Medicine, Faculty of Veterinary Medicine, University of Glasgow, Bearsden Road, Glasgow, G61 1QH, Scotland, UK.
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141
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von Zglinicki T, Martin-Ruiz CM, Saretzki G. Telomeres, cell senescence and human ageing. ACTA ACUST UNITED AC 2005. [DOI: 10.1002/sita.200400049] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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142
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Effros RB, Dagarag M, Spaulding C, Man J. The role of CD8+ T-cell replicative senescence in human aging. Immunol Rev 2005; 205:147-57. [PMID: 15882351 DOI: 10.1111/j.0105-2896.2005.00259.x] [Citation(s) in RCA: 228] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The strict limit in proliferative potential of normal human somatic cells - a process known as replicative senescence - is highly relevant to the immune system, because clonal expansion is fundamental to adaptive immunity. CD8(+) T cells that undergo extensive rounds of antigen-driven proliferation in cell culture invariably reach the end stage of replicative senescence, characterized by irreversible cell-cycle arrest and a critically short telomere length. Cultures of senescent CD8(+) T cells also show resistance to apoptosis, permanent loss of CD28 expression, altered cytokine profiles, reduced ability to respond to stress, and various functional changes. Cells with similar characteristics accumulate during normal aging as well as in younger persons infected with human immunodeficiency virus, suggesting that the process of replicative senescence is not an artifact of cell culture but is also occurring in vivo. Interestingly, in elderly persons, the presence of high proportions of CD8(+) T cells with characteristics of replicative senescence is correlated with reduced antibody responses to vaccines as well as with osteoporotic fractures. CD8(+)CD28(-) T cells also accumulate in patients with certain types of cancer. The emerging picture is that senescent CD8(+) T cells may modulate both immune and non-immune functions, contributing not only to reduced anti-viral immunity but also to diverse age-related pathologies.
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Affiliation(s)
- Rita B Effros
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
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143
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Kawauchi K, Ihjima K, Yamada O. IL-2 increases human telomerase reverse transcriptase activity transcriptionally and posttranslationally through phosphatidylinositol 3'-kinase/Akt, heat shock protein 90, and mammalian target of rapamycin in transformed NK cells. THE JOURNAL OF IMMUNOLOGY 2005; 174:5261-9. [PMID: 15843522 DOI: 10.4049/jimmunol.174.9.5261] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Human telomerase activity is induced by Ag receptor ligation in T and B cells. However, it is unknown whether telomerase activity is increased in association with activation and proliferation of NK cells. We found that telomerase activity in a human NK cell line (NK-92), which requires IL-2 for proliferation, was increased within 24 h after stimulation with IL-2. Levels of human telomerase reverse transcriptase (hTERT) mRNA and protein correlated with telomerase activity. ERK1/2 and Akt kinase (Akt) were activated by IL-2 stimulation. LY294002, an inhibitor of PI3K, abolished expression of hTERT mRNA and protein expression and abolished hTERT activity, whereas PD98059, which inhibits MEK1/2 and thus ERK1/2, had no effect. In addition, radicicol, an inhibitor of heat shock protein 90 (Hsp90), and rapamycin, an inhibitor of the mammalian target of rapamycin (mTOR), blocked IL-2-induced hTERT activity and nuclear translocation of hTERT but not hTERT mRNA expression. hTERT was coimmunoprecipitated with Akt, Hsp90, mTOR, and p70 S6 kinase (S6K), suggesting that these molecules form a physical complex. Immunoprecipitates of Akt, Hsp90, mTOR, and S6K from IL-2-stimulated NK-92 cells contained telomerase activity. Furthermore, the findings that Hsp90 and mTOR immunoprecipitates from primary samples contained telomerase activity are consistent with the results from NK-92 cells. These results indicate that IL-2 stimulation induces hTERT activation and that the mechanism of IL-2-induced hTERT activation involves transcriptional or posttranslational regulation through the pathway including PI3K/Akt, Hsp90, mTOR, and S6K in NK cells.
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MESH Headings
- Cell Line, Transformed
- Chromones/pharmacology
- DNA-Binding Proteins
- Enzyme Inhibitors/pharmacology
- Extracellular Signal-Regulated MAP Kinases/metabolism
- Flavonoids/pharmacology
- HSP90 Heat-Shock Proteins/physiology
- Humans
- Interleukin-2/antagonists & inhibitors
- Interleukin-2/physiology
- Killer Cells, Natural/enzymology
- Killer Cells, Natural/immunology
- Killer Cells, Natural/metabolism
- Lactones/pharmacology
- Leukemia, Lymphocytic, Chronic, B-Cell/enzymology
- Leukemia, Lymphoid/enzymology
- Lymphocyte Activation/immunology
- Macrolides
- Morpholines/pharmacology
- Phosphatidylinositol 3-Kinases/physiology
- Protein Kinases/physiology
- Protein Processing, Post-Translational/immunology
- Protein Serine-Threonine Kinases/metabolism
- Proto-Oncogene Proteins/metabolism
- Proto-Oncogene Proteins c-akt
- RNA-Directed DNA Polymerase/metabolism
- Ribosomal Protein S6 Kinases, 70-kDa/metabolism
- Sirolimus/pharmacology
- TOR Serine-Threonine Kinases
- Telomerase/antagonists & inhibitors
- Telomerase/genetics
- Telomerase/metabolism
- Transcription, Genetic/immunology
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Affiliation(s)
- Kiyotaka Kawauchi
- Department of Medicine, Daini Hospital, Tokyo Women's Medical University, Arakawa-ku, Tokyo, Japan
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144
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Marinova E, Han S, Zheng B. Age-associated deficiency in activation-induced up-regulation of telomerase activity in CD4+ T cells. Clin Exp Immunol 2005; 140:258-64. [PMID: 15807849 PMCID: PMC1809353 DOI: 10.1111/j.1365-2249.2005.02762.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
For lymphocytes, the ability to undergo clonal expansion is crucial for effective immune function. Telomerase activity compensates for telomere erosion during cell division and contributes to the capability of lymphocytes to maintain cellular proliferation. In addition, telomerase activity may have a fundamental role in cell growth and survival. To determine whether age-related immune dysfunction is associated with an abnormality in telomerase activity, we investigated telomerase activity in T cell populations from young adult and aged mice. Our data show that the ability of T cells from aged mice to up-regulate telomerase activity after activation was significantly diminished. This age-related deficiency in telomerase induction is restricted to CD4(+) T cells, as CD8(+) T cells retain the capability to up-regulate telomerase activity. These findings reinforce the notion that age-related immune dysfunction results mainly from impairment of helper T cells, and may have important implications for designing novel means to improve immune responses in aged individuals by enhancing CD8(+) T cell functions, which are crucial in both viral and tumour immunity.
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Affiliation(s)
- E Marinova
- Department of Immunology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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145
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Kundra V, Krane JF, Nikolaidis P, Green DS, Zou KH, Tuncali K, Vansonnenberg E, Silverman SG. Telomerase activity predicts malignancy in percutaneous image-guided needle biopsy specimens of the abdomen and pelvis. Radiology 2005; 234:941-7. [PMID: 15734943 DOI: 10.1148/radiol.2343031701] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
PURPOSE To determine prospectively if assessment of telomerase activity in percutaneous needle biopsy specimens improves sensitivity and specificity in the diagnosis of abdominal and pelvic malignancy. MATERIALS AND METHODS The study was approved by the institutional review board, and written informed consent was obtained from all patients. A prospective double-blinded design was used to assess telomerase activity in abdominal and pelvic biopsy specimens from 99 patients (64 men, 35 women; age range, 22-87 years). After the clinical sample was retrieved, a study specimen from an extra needle pass was divided and independently analyzed for cytologic characteristics and telomerase activity. The final diagnosis was based on chart review at a minimum 1-year follow-up. Statistical analyses included sensitivity, specificity, and accuracy of cytologic examination and/or telomerase activity in predicting malignancy. RESULTS Data from study specimens indicated that the sensitivity, specificity, and accuracy of telomerase activity (n=99) in predicting malignancy were 55%, 79%, and 60%, respectively. For cytologic examination (n=86), the sensitivity, specificity, and accuracy in predicting malignancy were 74%, 94%, and 78%, respectively. Combining the two tests (n=86) and classifying a positive reading with either test as malignant improved sensitivity (83%) (P <.05) without altering specificity (76%). In 20 patients who had clinical sample reports that were classified as indeterminate, telomerase activity (n=20) yielded a higher sensitivity (62%) (P <.05) and similar specificity (86%) compared with cytologic examination (n=15), which yielded a sensitivity of 11% and a specificity of 83%. CONCLUSION In percutaneous biopsy specimens of the abdomen and pelvis, the combination of cytologic examination and telomerase activity yielded an increased sensitivity in predicting malignancy. In addition, assessing telomerase activity can help identify cancer even when cytologic results are indeterminate.
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Affiliation(s)
- Vikas Kundra
- Division of Abdominal Imaging and Intervention, Department of Radiology and Division of Cytology, Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Mass, USA.
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146
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Thewissen M, Linsen L, Geusens P, Raus J, Stinissen P. Impaired activation-induced telomerase activity in PBMC of early but not chronic rheumatoid arthritis patients. Immunol Lett 2005; 100:205-10. [PMID: 16154497 DOI: 10.1016/j.imlet.2005.03.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2004] [Revised: 03/09/2005] [Accepted: 03/18/2005] [Indexed: 11/27/2022]
Abstract
Although telomerase activity is important in normal immune function, it is unclear whether telomerase or telomerase (dys)regulation plays a role in the pathogenic immune response in autoimmune diseases like rheumatoid arthritis (RA). In this study, we evaluated the dynamics of the activation-induced human telomerase reverse transcriptase (hTERT) response in RA patients and non-RA controls. The expression of the catalytic subunit of telomerase, hTERT, was measured in peripheral blood mononuclear cells (PBMC) of RA patients and controls after in vitro stimulation with anti-CD3 monoclonal antibody (mAb) using real-time PCR. Anti-CD3 mAb stimulation induced activation and proliferation of the T cells in all populations studied. In early RA patients with a disease duration of less than 1 year, the activation-induced hTERT mRNA levels were found to be reduced as compared to healthy controls (HC). Chronic RA patients, with a disease duration of more than 1 year, did not show these impaired hTERT mRNA levels after stimulation with anti-CD3 mAb. Decreased hTERT mRNA levels were also found in multiple sclerosis patients and patients suffering from flu-like symptoms, indicating that these deviations are not disease-specific. The impaired activation-induced hTERT response in PBMC may be a general response of the immune cells in cases of acute or chronic immune activation, presumably to control unwanted clonal expansions and to maintain the diversity of the TCR repertoire. Our results also indicate that clonal T cell expansions, described in RA, are probably not mediated by an elevated potency to express hTERT.
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Affiliation(s)
- Marielle Thewissen
- Biomedisch Onderzoeksinstituut, Limburgs Universitair Centrum and School of Life Sciences, Transnationale Universiteit Limburg, Universitaire Campus, B-3590 Diepenbeek, Belgium
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147
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Affiliation(s)
- Barbara A Gilchrest
- Department of Dermatology, Boston University School of Medicine, Boston, MA 02118, USA
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148
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Li Y, Zhi W, Wareski P, Weng NP. IL-15 Activates Telomerase and Minimizes Telomere Loss and May Preserve the Replicative Life Span of Memory CD8+T Cells In Vitro. THE JOURNAL OF IMMUNOLOGY 2005; 174:4019-24. [PMID: 15778359 DOI: 10.4049/jimmunol.174.7.4019] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The preservation of the replicative life span of memory CD8(+) T cells is vital for long-term immune protection. Although IL-15 plays a key role in the homeostasis of memory CD8(+) T cells, it is unknown whether IL-15 regulates the replicative life span of memory CD8(+) T cells. In this study, we report an analysis of telomerase expression and telomere length in human memory phenotype CD8(+) T cells maintained by IL-15 in vitro. We demonstrate that IL-15 is capable of activating telomerase in memory CD8(+) T cells via Jak3 and PI3K signaling pathways. Furthermore, IL-15 induces a sustained level of telomerase activity over long periods of time, and in turn minimizes telomere loss in memory CD8(+) T cells after substantial cell divisions. These findings suggest that IL-15 activates stable telomerase expression and compensates telomere loss in memory phenotype CD8(+) T cells, and that telomerase may play an important role in memory CD8(+) T cell homeostasis.
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Affiliation(s)
- Yu Li
- Laboratory of Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
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149
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Röth A, Baerlocher GM, Schertzer M, Chavez E, Dührsen U, Lansdorp PM. Telomere loss, senescence, and genetic instability in CD4+ T lymphocytes overexpressing hTERT. Blood 2005; 106:43-50. [PMID: 15741219 PMCID: PMC1895130 DOI: 10.1182/blood-2004-10-4144] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Little is known about the long-term consequences of overexpression of the human telomerase reverse transcriptase (hTERT) gene in T lymphocytes. To address this issue, we transduced polyclonal as well as clonally derived populations of naive and memory CD44 T cells from 2 healthy donors (aged 24 and 34 years) with retroviral vectors encoding green fluorescence protein (GFP) and hTERT (GFP-hTERT) or GFP alone. After transduction, cells were sorted on the basis of GFP expression and cultured in vitro until senescence. T cells transduced with hTERT exhibited high stable telomerase activity throughout the culture period. Relative to GFP controls, minor changes in overall gene expression were observed yet the proliferative lifespan of the hTERT-transduced populations was significantly increased and the rate of telomere loss was lower. Nevertheless, hTERT-transduced cells showed progressive telomere loss and had shorter telomeres at senescence than controls (2.3 +/- 0.3 kilobase [kb] versus 3.4 +/- 0.1 kb). Furthermore, a population of cells with 4N DNA consisting of binucleated cells with connected nuclei emerged in the hTERT-transduced cells prior to senescence. We conclude that overexpression of hTERT in CD4+ T cells provides a proliferative advantage independent of the average telomere length but does not prevent eventual genetic instability and replicative senescence.
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Affiliation(s)
- Alexander Röth
- Terry Fox Laboratory, British Columbia Cancer Agency, 12th floor, 675 W 10th Ave, Vancouver, BC, V5Z 1L3, Canada
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150
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Zanetti M, Hernandez X, Langlade-Demoyen P. Telomerase reverse transcriptase as target for anti-tumor T cell responses in humans. ACTA ACUST UNITED AC 2005; 27:87-104. [PMID: 15711953 DOI: 10.1007/s00281-004-0197-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2004] [Accepted: 12/15/2004] [Indexed: 10/25/2022]
Abstract
Human telomerase reverse transcriptase, a ribonucleoprotein intimately connected with the process of cell immortalization, is overexpressed in the vast majority of cancer cells, irrespective of their histological origin. Telomerase is currently viewed as the first antigen with the characteristics of common tumor antigen in humans, and it constitutes a potentially valuable target for attempts to control tumors through CD8 T cell immunity. Telomerase is a self antigen, making it possible that self tolerance imposes severe restrictions on our ability to generate effective anti-tumor immune responses in humans. In this article we review current studies on the antigenic and immunogenic properties of the human telomerase reverse transcriptase, placing them in the context of self tolerance and the size of the available CD8 T cell repertoire restricted by the HLA A2 molecule.
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Affiliation(s)
- Maurizio Zanetti
- The Laboratory of Immunology, Department of Medicine and Cancer Center, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0837, USA.
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