101
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Multiple sclerosis: a disorder of altered T-cell homeostasis. Mult Scler Int 2011; 2011:461304. [PMID: 22096637 PMCID: PMC3197186 DOI: 10.1155/2011/461304] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Accepted: 07/21/2011] [Indexed: 11/17/2022] Open
Abstract
Uncertainty exists as to whether similar or different mechanisms contribute to the pathogenesis of different subtypes of multiple sclerosis (MS). Detailed analysis of naive T cell homeostasis shows that patients with relapsing-remitting MS (RRMS) and with primary progressive MS (PPMS) have early-onset thymic involution that causes reduced thymic output. The reduced thymic output leads to secondary peripheral homeostatic alterations in naïve CD4 T-cells, which closely mimic T-cell alterations observed in an experimental animal model of diabetes mellitus. Homeostatic T-cell receptor (TCR) signalling and proliferation of naïve T cells are induced by self-peptides. Consequently, the findings of increased TCR signalling of naïve CD4 T-cells, without increased proliferation, in PPMS, and the increased homeostatic proliferation of naïve CD4 T-cells in RRMS favour the development of autoimmunity. Thus, it seems highly likely that peripheral T-cell alterations secondary to a thymic abnormality contribute to the pathogenesis of both MS subtypes.
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102
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Evans VA, Lal L, Akkina R, Solomon A, Wright E, Lewin SR, Cameron PU. Thymic plasmacytoid dendritic cells are susceptible to productive HIV-1 infection and efficiently transfer R5 HIV-1 to thymocytes in vitro. Retrovirology 2011; 8:43. [PMID: 21639903 PMCID: PMC3118182 DOI: 10.1186/1742-4690-8-43] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2010] [Accepted: 06/03/2011] [Indexed: 01/28/2023] Open
Abstract
Background HIV-1 infection of the thymus contributes to the defective regeneration and loss of CD4+ T cells in HIV-1-infected individuals. As thymic dendritic cells (DC) are permissive to infection by HIV-1, we examined the ability of thymic DC to enhance infection of thymocytes which may contribute to the overall depletion of CD4+ T cells. We compared productive infection in isolated human thymic and blood CD11c+ myeloid DC (mDC) and CD123+ plasmacytoid DC (pDC) using enhanced green fluorescent protein (EGFP) CCR5 (R5)-tropic NL(AD8) and CXCR4 (X4)-tropic NL4-3 HIV-1 reporter viruses. Transfer of productive HIV-1 infection from thymic mDC and pDC was determined by culturing these DC subsets either alone or with sorted thymocytes. Results Productive infection was observed in both thymic pDC and mDC following exposure to R5 HIV-1 and X4 HIV-1. Thymic pDC were more frequently productively infected by both R5 and X4 HIV-1 than thymic mDC (p = 0.03; n = 6). Thymic pDC efficiently transferred productive R5 HIV-1 infection to both CD3hi (p = 0.01; mean fold increase of 6.5; n = 6) and CD3lo thymocytes (mean fold increase of 1.6; n = 2). In comparison, transfer of productive infection by thymic mDC was not observed for either X4 or R5 HIV-1. Conclusions The capacity of thymic pDC to efficiently transfer R5 HIV-1 to both mature and immature thymocytes that are otherwise refractory to R5 virus may represent a pathway to early infection and impaired production of thymocytes and CD4+ T cells in HIV-1-infected individuals.
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Affiliation(s)
- Vanessa A Evans
- Monash University, Department of Medicine, Central and Eastern Clinical School, Alfred Campus, Commercial Rd., Melbourne, Victoria 3004, Australia
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103
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Abstract
OBJECTIVE The contribution of naive CD4⁺ T cells to the pool of HIV-infected cells remains poorly described. This study aimed at evaluating HIV infection in naive T-cell subsets in viremic and HAART-treated patients, together with various parameters implicated in naive T-cell homeostasis, in order to better understand infection in these subsets. DESIGN AND METHODS HIV provirus was quantified in various FACS-sorted CD4/CD8 T-cell subsets [recent thymic emigrants (RTEs), non-RTE naives and memory T cells] purified from peripheral blood cells of untreated viremic and HAART-treated aviremic HIV-infected patients. HIV proviral DNA was quantified using a highly sensitive real-time PCR assay allowing detection of one HIV copy in 10⁵ cells. Intrathymic precursor T-cell proliferation and circulating T-cell cycling were, respectively, evaluated through measurement of the sj/βTREC ratio (signal joint T-Cell Receptor Excision Circle frequency divided by DβJβTREC frequency) and Ki-67 expression. Plasma interleukin (IL)-7 concentrations were measured by ELISA. RESULTS RTEs and non-RTEs were equally HIV infected. Altogether, naive CD4⁺ T cells represented 0.24%-60% of the infected cells. In contrast, HIV DNA was undetectable in naive CD8⁺ T cells. RTE infection rate directly correlated with IL-7 plasma levels (r = 0.607, P = 0.0035) but was independent from plasma viral load, peripheral T-cell cycling and intrathymic precursor T-cell proliferation. CONCLUSION We demonstrated that RTEs are effectively HIV infected. The similar infection rate observed in RTEs and other naive T cells, its relationship with plasma IL-7 levels, together with the lack of correlation between RTE infection and either thymic or peripheral proliferation, strongly suggests that RTE infection occurs either late during thymopoiesis or early on during their extrathymic maturation.
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104
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Chronic Δ-9-tetrahydrocannabinol administration increases lymphocyte CXCR4 expression in rhesus macaques. J Neuroimmune Pharmacol 2011; 6:540-5. [PMID: 21484257 DOI: 10.1007/s11481-011-9277-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Accepted: 03/21/2011] [Indexed: 01/13/2023]
Abstract
Cannabinoids have been reported to produce various immunomodulatory effects, which could potentially impact the host response to bacterial or viral infection. We have recently demonstrated that chronic Δ-9-tetrahydrocannabinol (THC; 0.32 mg/kg i.m., BID) decreased early mortality in rhesus macaques infected with simian immunodeficiency virus (SIV). However, the possibility that prolonged THC administration affects lymphocyte counts, phenotype, and proliferation indices has not been addressed. We examined expression of proliferative and phenotypic markers in circulating lymphocytes of male young adult rhesus macaques chronically-treated with THC (i.m. twice daily 0.32 mg/kg) for 12 months. Chronic THC administration did not alter lymphocyte subtypes, naïve and memory subsets, proliferation, or apoptosis of T lymphocytes when compared to time-matched vehicle-treated controls. However, chronic THC increased T lymphocyte CXCR4 expression on both CD4+ and CD8+ T lymphocytes compared to control. These results show that chronic THC administration produces changes in T cell phenotype, which can potentially contribute to host immunomodulation to infectious challenges.
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105
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HIV disease progression despite suppression of viral replication is associated with exhaustion of lymphopoiesis. Blood 2011; 117:5142-51. [PMID: 21436070 DOI: 10.1182/blood-2011-01-331306] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The mechanisms of CD4(+) T-cell count decline, the hallmark of HIV disease progression, and its relationship to elevated levels of immune activation are not fully understood. Massive depletion of CD4(+) T cells occurs during the course of HIV-1 infection, so that maintenance of adequate CD4(+) T-cell levels probably depends primarily on the capacity to renew depleted lymphocytes, that is, the lymphopoiesis. We performed here a comprehensive study of quantitative and qualitative attributes of CD34(+) hematopoietic progenitor cells directly from the blood of a large set of HIV-infected persons compared with uninfected donors, in particular the elderly. Our analyses underline a marked impairment of primary immune resources with the failure to maintain adequate lymphocyte counts. Systemic immune activation emerges as a major correlate of altered lymphopoiesis, which can be partially reversed with prolonged antiretroviral therapy. Importantly, HIV disease progression despite elite control of HIV replication or virologic success on antiretroviral treatment is associated with persistent damage to the lymphopoietic system or exhaustion of lymphopoiesis. These findings highlight the importance of primary hematopoietic resources in HIV pathogenesis and the response to antiretroviral treatments.
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106
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Abstract
Cytoreductive conditioning regimens used in the context of allogeneic hematopoietic cell transplantation (HCT) elicit deficits in innate and adaptive immunity, which predispose patients to infections. As such, transplantation outcomes depend vitally on the successful reconstruction of immune competence. Restoration of a normal peripheral T-cell pool after HCT is a slow process that requires the de novo production of naive T cells in a functionally competent thymus. However, there are several challenges to this regenerative process. Most notably, advanced age, the cytotoxic pretransplantation conditioning, and posttransplantation alloreactivity are risk factors for T-cell immune deficiency as they independently interfere with normal thymus function. Here, we discuss preclinical allogeneic HCT models and clinical observations that have contributed to a better understanding of the transplant-related thymic dysfunction. The identification of the cellular and molecular mechanisms that control regular thymopoiesis but are altered in HCT patients is expected to provide the basis for new therapies that improve the regeneration of the adaptive immune system, especially with functionally competent, naive T cells.
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107
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Abstract
The inevitable decline of CD4T cells in untreated infection with the Human immunodeficiency virus (HIV) is due in large part to apoptosis, one type of programmed cell death. There is accumulating evidence that the accelerated apoptosis of CD4T cells in HIV infection is multifactorial, with direct viral cytotoxicity, signaling events triggered by viral proteins and aberrant immune activation adding to normal immune defense mechanisms to contribute to this phenomenon. Current antiviral treatment strategies generally lead to reduced apoptosis, but this approach may come at the cost of preserving latent viral reservoirs. It is the purpose of this review to provide an update on the current understanding of the role and mechanisms of accelerated apoptosis of T cells in the immunopathogenesis of HIV infection, and to highlight potential ways in which this seemingly deleterious process could be harnessed to not just control, but treat HIV infection.
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108
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Castermans E, Hannon M, Dutrieux J, Humblet-Baron S, Seidel L, Cheynier R, Willems E, Gothot A, Vanbellinghen JF, Geenen V, Sandmaier BM, Storb R, Beguin Y, Baron F. Thymic recovery after allogeneic hematopoietic cell transplantation with non-myeloablative conditioning is limited to patients younger than 60 years of age. Haematologica 2010; 96:298-306. [PMID: 20934996 DOI: 10.3324/haematol.2010.029702] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Long-term immune recovery in older patients given hematopoietic cell transplantation after non-myeloablative conditioning remains poorly understood. This prompted us to investigate long-term lymphocyte reconstitution and thymic function in 80 patients given allogeneic peripheral blood stem cells after non-myeloablative conditioning. DESIGN AND METHODS Median age at transplant was 57 years (range 10-71). Conditioning regimen consisted of 2 Gy total body irradiation (TBI) with (n=46) or without (n=20) added fludarabine, 4 Gy TBI with fludarabine (n=6), or cyclophosphamide plus fludarabine (n=8). Stem cell sources were unmanipulated (n=56), CD8-depleted (n=19), or CD34-selected (n=5) peripheral blood stem cells. Immune recovery was assessed by signal-joint T-cell receptor excision circle quantification and flow cytometry. RESULTS Signal-joint T-cell receptor excision circle levels increased from day 100 to one and two years after transplantation in patients under 50 years of age (n=23; P=0.02 and P=0.04, respectively), and in those aged 51-60 years (n=35; P=0.17 and P=0.06, respectively), but not in patients aged over 60 (n=22; P=0.3 and P=0.3, respectively). Similarly, CD4(+)CD45RA(+) (naïve) T-cell counts increased from day 100 to one and two years after transplantation in patients aged 50 years and under 50 (P=0.002 and P=0.02, respectively), and in those aged 51-60 (P=0.4 and P=0.001, respectively), but less so in patients aged over 60 (P=0.3 and P=0.06, respectively). In multivariate analyses, older patient age (P<0.001), extensive chronic GVHD (P<0.001), and prior (resolved) extensive chronic graft-versus-host disease (P=0.008) were associated with low signal-joint T-cell receptor excision circle levels one year or more after HCT. CONCLUSIONS In summary, our data suggest that thymic neo-generation of T cells occurred from day 100 onwards in patients under 60 while signal-joint T-cell receptor excision circle levels remained low for patients aged over 60. Further, chronic graft-versus-host disease had a dramatic impact on thymic function, as observed previously in patients given grafts after myeloablative conditioning.
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Affiliation(s)
- Emilie Castermans
- University of Liège, Department of Hematology, CHU Sart-Tilman, 4000 Liège, Belgium
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109
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Interleukin-7 treatment counteracts IFN-α therapy-induced lymphopenia and stimulates SIV-specific cytotoxic T lymphocyte responses in SIV-infected rhesus macaques. Blood 2010; 116:5589-99. [PMID: 20841508 DOI: 10.1182/blood-2010-03-276261] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Interferon-α (IFN-α)-based therapy is presently the standard treatment for hepatitis C virus (HCV)-infected patients. Despite good effectiveness, this cytokine is associated with major side effects, including significant lymphopenia, that limits its use for HIV/HCV-coinfected patients. Interleukin-7 (IL-7) has recently shown therapeutic potential and safety in several clinical trials designed to demonstrate T-cell restoration in immunodeficient patients. The purpose of this study was to evaluate, in simian immunodeficiency virus-infected rhesus macaques, the relevance of IL-7 therapy as a means to overcoming IFN-α-induced lymphopenia. We showed that low-dose IFN-α treatment induced strong lymphopenia in chronically infected monkeys. In contrast, high-dose IFN-α treatment stimulated IL-7 production, leading to increased circulating T-cell counts. Moreover, IL-7 therapy more than abrogated the lymphopenic effect of low-dose IFN-α. Indeed, the association of both cytokines resulted in increased circulating T-cell counts, in particular in the naive compartments, as a consequence of central and peripheral homeostatic functions of the IL-7. Finally, reduced PD-1 expression by memory CD8(+) T cells and transient T-cell repertoire diversification were observed under IL-7 therapy. Our data strongly suggest that IL-7 immunotherapy will be of substantial benefit in the treatment of HIV/HCV coinfection and should enhance the likelihood of HCV eradication in poorly responding patients.
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110
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Bandera A, Ferrario G, Saresella M, Marventano I, Soria A, Zanini F, Sabbatini F, Airoldi M, Marchetti G, Franzetti F, Trabattoni D, Clerici M, Gori A. CD4+ T cell depletion, immune activation and increased production of regulatory T cells in the thymus of HIV-infected individuals. PLoS One 2010; 5:e10788. [PMID: 20520721 PMCID: PMC2875388 DOI: 10.1371/journal.pone.0010788] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Accepted: 04/19/2010] [Indexed: 01/06/2023] Open
Abstract
Mechanisms by which HIV affects the thymus are multiple and only partially known, and the role of thymic dysfunction in HIV/AIDS immunopathogenesis remains poorly understood. To evaluate the effects of HIV infection on intra-thymic precursors of T cells in HIV-infected adults, we conducted a detailed immunophenotypic study of thymic tissue isolated from 7 HIV-infected and 10 HIV-negative adults who were to undergo heart surgery. We found that thymuses of HIV-infected individuals were characterized by a relative depletion of CD4+ single positive T cells and a corresponding enrichment of CD8+ single positive T cells. In addition, thymocytes derived from HIV-infected subjects showed increased levels of activated and proliferating cells. Our analysis also revealed a decreased expression of interleukin-7 receptor in early thymocytes from HIV-infected individuals, along with an increase in this same expression in mature double- and single-positive cells. Frequency of regulatory T cells (CD25+FoxP3+) was significantly increased in HIV-infected thymuses, particularly in priorly-committed CD4 single positive cells. Our data suggest that HIV infection is associated with a complex set of changes in the immunophenotype of thymocytes, including a reduction of intrathymic CD4+ T cell precursors, increased expression of activation markers, changes in the expression pattern of IL-7R and enrichment of T regulatory cells generation.
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Affiliation(s)
- Alessandra Bandera
- Division of Infectious Diseases, Department of Internal Medicine, San Gerardo Hospital, University of Milan-Bicocca, Monza, Italy.
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111
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Duszczyszyn DA, Williams JL, Mason H, Lapierre Y, Antel J, Haegert DG. Thymic involution and proliferative T-cell responses in multiple sclerosis. J Neuroimmunol 2010; 221:73-80. [PMID: 20223525 DOI: 10.1016/j.jneuroim.2010.02.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2009] [Revised: 01/08/2010] [Accepted: 02/08/2010] [Indexed: 01/06/2023]
Abstract
We investigated naïve CD4 T-cell homeostasis in relapsing-remitting multiple sclerosis (RRMS). Quantification of signal joint T-cell receptor excision circles in FACS-isolated CD31hi cells, which correspond closely to CD4 recent thymic emigrants (RTEs), indicates that young patients have reduced generation of CD4 RTEs compared to age-matched controls. In RRMS, compared to controls, CXCR4 analyses indicate age-associated thymic output of progressively immature CD4 RTEs, and Ki-67 data demonstrate altered T-cell proliferative responses that fail to maintain naïve CD4 T-cell numbers with age. Thus, RRMS patients have early thymic involution with compensatory homeostatic peripheral T-cell proliferative responses that may predispose patients to autoreactivity.
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112
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Nunes‐Cabaço H, Ribot JC, Caramalho Í, Serra‐Caetano A, Silva‐Santos B, Sousa AE. Foxp3 induction in human and murine thymus precedes the CD4
+
CD8
+
stage but requires early T‐cell receptor expression. Immunol Cell Biol 2010; 88:523-8. [DOI: 10.1038/icb.2010.4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Helena Nunes‐Cabaço
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa Lisboa Portugal
| | - Julie C Ribot
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa Lisboa Portugal
- Instituto Gulbenkian de Ciência Oeiras Portugal
| | - Íris Caramalho
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa Lisboa Portugal
| | - Ana Serra‐Caetano
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa Lisboa Portugal
| | - Bruno Silva‐Santos
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa Lisboa Portugal
- Instituto Gulbenkian de Ciência Oeiras Portugal
| | - Ana E Sousa
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa Lisboa Portugal
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113
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Ganesan A, Chattopadhyay PK, Brodie TM, Qin J, Gu W, Mascola JR, Michael NL, Follmann DA, Roederer M. Immunologic and virologic events in early HIV infection predict subsequent rate of progression. J Infect Dis 2010; 201:272-84. [PMID: 20001854 PMCID: PMC2939466 DOI: 10.1086/649430] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Variability in human immunodeficiency virus (HIV) disease progression cannot be fully predicted by CD4(+) T cell counts or viral load (VL). Because central memory T (T(CM)) cells play a critical role in the pathogenesis of simian immunodeficiency virus disease, we hypothesized that quantifying these cells in early HIV infection could provide prognostic information. METHODS We measured expression of CD45RO, chemokine (C-C motif) receptor (CCR) 5, CCR7, CD27, and CD28 to enumerate naive and memory subsets in samples from recently infected individuals. We also quantified proliferation, CD127 expression, and cell-associated VL. Disease progression was compared across subgroups defined by these measurements, using Kaplan-Meier survival curves and multivariate Cox proportional hazards regression. RESULTS Four hundred sixty-six subjects contributed 101 events. The proportion or absolute count of T(CM) cells did not correlate with disease progression, defined as the time to AIDS or death. However, significant associations were observed for proliferation within CD4(+) or CD8(+) T cells, loss of naive or CD127(+) memory CD8(+) T cells, and CD4(+) T cell-associated VL. CONCLUSIONS Our results demonstrate that the extent of the immunopathogenesis established early in HIV infection predicts the course of future disease. Because antiretroviral drug treatment reverses such defects in part, our study provides mechanistic clues to why early use of antiretrovirals may prove beneficial.
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Affiliation(s)
- Anuradha Ganesan
- National Naval Medical Center, Infectious Disease Clinical Research Program, Uniformed Services University, Bethesda, MD
| | - Pratip K. Chattopadhyay
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, Bethesda, MD
| | - Tess M. Brodie
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, Bethesda, MD
| | - Jing Qin
- Biostatistics Research Branch, National Institute of Allergy and Infectious Diseases, Bethesda, MD
| | - Wenjuan Gu
- Biostatistics Research Branch, SAIC-Frederick, Inc, Frederick, MD
| | - John R. Mascola
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, Bethesda, MD
| | - Nelson L. Michael
- United States Military HIV Research Program, Walter Reed Army Institute of Research, Rockville, MD
| | - Dean A. Follmann
- Biostatistics Research Branch, National Institute of Allergy and Infectious Diseases, Bethesda, MD
| | - Mario Roederer
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, Bethesda, MD
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114
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Downey JS, Imami N. T-cell dysfunction in HIV-1 infection: targeting the inhibitors. ACTA ACUST UNITED AC 2010. [DOI: 10.2217/hiv.09.51] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Since AIDS emerged almost three decades ago, there have been considerable advances in the field of antiretroviral chemotherapy for those chronically infected with HIV-1. However, this therapy is noncurative and as our understanding of HIV-1 immunopathogenesis increases, it is becoming apparent that further therapeutic interventions are required to reverse the devastating effects of HIV-1 infection worldwide. While viral clearance remains the principle goal of HIV-1 treatment, this article describes immunotherapeutic options that target the immunological effects of the virus, to reduce its presence in the body and counteract viral-induced T-cell dysfunction and inhibition. Such approaches may augment existing antiretroviral therapy to overturn virus-induced T-cell anergy in the infected host, improving levels of immune control that reduce viremia and decrease the rate of transmission.
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Affiliation(s)
- Jocelyn S Downey
- Department of Immunology, Imperial College London, Chelsea & Westminster Hospital, 369 Fulham Road, London, SW10 9NH, UK
| | - Nesrina Imami
- Department of Immunology, Imperial College London, Chelsea & Westminster Hospital, 369 Fulham Road, London, SW10 9NH, UK
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115
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Abstract
PURPOSE OF REVIEW Significant gastrointestinal pathology occurs in progressive HIV and simian immunodeficiency virus (SIV) infections. This review will examine the relationship between the detrimental events to the gastrointestinal tract during the acute phase of infection and disease progression through the chronic phase and, ultimately, AIDS. RECENT FINDINGS Gastrointestinal tract CD4 T cells are dramatically depleted in acutely HIV-infected humans and SIV-infected rhesus macaques, sooty mangabeys, and African green monkeys. In addition HIV infection of humans and SIV-infection of rhesus macaques are characterized by enteropathy and increased intestinal permeability. While SIV-infected rhesus macaques and HIV-infected humans manifest chronic and systemic immune activation and microbial translocation, and progress to chronic infection and AIDS, however, SIV-infected sooty mangabeys and African green monkeys do not. SUMMARY Recent studies have increased our understanding of the mechanisms relating structural and immunological damage to the gastrointestinal tract during the acute phase of HIV/SIV infection to immune activation and disease progression in the chronic phase.
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116
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Chiarini M, Sottini A, Ghidini C, Zanotti C, Serana F, Rottoli M, Zaffaroni M, Bergamaschi R, Cordioli C, Capra R, Imberti L. Renewal of the T-cell compartment in multiple sclerosis patients treated with glatiramer acetate. Mult Scler 2009; 16:218-27. [PMID: 20007428 DOI: 10.1177/1352458509355460] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The immunomodulating activity of glatiramer acetate on T-cells of multiple sclerosis patients has only been partially clarified. The objective of this work was to investigate whether glatiramer acetate modifies thymic release of newly produced T-cells and the peripheral composition of the T-cell repertoire. T-cell receptor excision circles, (thymic) naive (CD4(+)CD45RA(+)CCR7(+)CD31(+)) T helper cells, and central (CD4(+)CD45RA(-)CCR7(+)) and effector (CD4(+)CD45RA(-)CCR7(-)) memory T-cells were evaluated in 89 untreated patients, 84 patients treated for at least 1 year, and 31 patients beginning treatment at the time of inclusion in the study and then followed-up for 12 months; controls were 81 healthy donors. The T-cell repertoire was analysed in selected samples. The percentage of (thymic)naive T helper cells was diminished in untreated patients, but rose to control values in treated subjects; a decrease in central memory T-cells was also observed in treated patients. Follow-up patients could be divided into two subgroups, one showing unmodified (thymic)naive T helper cells and T-cell diversity, the other in which the increased release of new T-cells was accompanied by modifications of the T-cell repertoire. Glatiramer acetate modifies the peripheral T-cell pool by activating a thymopoietic pathway of T-cell release that leads to a different setting of T-cell diversity and, likely, to a dilution of autoreactive T-cells.
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Affiliation(s)
- M Chiarini
- Laboratorio di Biotecnologie, Diagnostics Department, Spedali Civili di Brescia, Italy
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117
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Ferrando-Martínez S, Franco JM, Ruiz-Mateos E, Hernández A, Ordoñez A, Gutierrez E, Leal M. A reliable and simplified sj/beta-TREC ratio quantification method for human thymic output measurement. J Immunol Methods 2009; 352:111-7. [PMID: 19919841 DOI: 10.1016/j.jim.2009.11.007] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Revised: 11/05/2009] [Accepted: 11/10/2009] [Indexed: 01/06/2023]
Abstract
Current techniques to peripherally assess thymic function are: the signal-joint T-cell receptor excision circle (sj-TREC) level measurement and the naive T cell and CD31+ TREC-rich subset determination. However, all of them are indirect approaches and none could be considered a direct recent thymic emigrant (RTE) marker. To overcome their limitations, Dion et al. (2004) described the sj/beta-TREC ratio that allows the peripheral quantification of the double negative to double positive intrathymic proliferation step. Nevertheless, the protocol described is expensive, sample and time-consuming, thus, limiting its usefulness. In this study, we describe a simplified protocol that reduces from 33 to 9 the amount of PCR reaction needed but maintaining the sensitivity and reproducibility of the original technique. In addition, we corroborated the effectiveness of our technique as an accurate thymic output-related marker by correlating the peripheral sj/beta-TREC ratio with a direct measurement of thymic function as the percentage of double positive thymocytes (r=0.601, p<0.001).
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Affiliation(s)
- Sara Ferrando-Martínez
- Laboratory of Immunovirology, Biomedicine Institute of Seville, Service of Infectious Diseases, Virgen del Rocio University Hospital, Avda. Manuel Siurot s/n 41013 Seville, Spain
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118
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Mavigner M, Delobel P, Cazabat M, Dubois M, L'Faqihi-Olive FE, Raymond S, Pasquier C, Marchou B, Massip P, Izopet J. HIV-1 residual viremia correlates with persistent T-cell activation in poor immunological responders to combination antiretroviral therapy. PLoS One 2009; 4:e7658. [PMID: 19876401 PMCID: PMC2765414 DOI: 10.1371/journal.pone.0007658] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2009] [Accepted: 10/12/2009] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND The clinical significance and cellular sources of residual human immunodeficiency virus type 1 (HIV-1) production despite suppressive combination antiretroviral therapy (cART) remain unclear and the effect of low-level viremia on T-cell homeostasis is still debated. METHODOLOGY/PRINCIPAL FINDINGS We characterized the recently produced residual viruses in the plasma and short-lived blood monocytes of 23 patients with various immunological responses to sustained suppressive cART. We quantified the residual HIV-1 in the plasma below 50 copies/ml, and in the CD14(high) CD16(-) and CD16+ monocyte subsets sorted by flow cytometry, and predicted coreceptor usage by genotyping V3 env sequences. We detected residual viremia in the plasma of 8 of 10 patients with poor CD4+ T-cell reconstitution in response to cART and in only 5 of 13 patients with good CD4+ T-cell reconstitution. CXCR4-using viruses were frequent among the recently produced viruses in the plasma and in the main CD14(high) CD16(-) monocyte subset. Finally, the residual viremia was correlated with persistent CD4+ and CD8+ T-cell activation in patients with poor immune reconstitution. CONCLUSIONS Low-level viremia could result from the release of archived viruses from cellular reservoirs and/or from ongoing virus replication in some patients. The compartmentalization of the viruses between the plasma and the blood monocytes suggests at least two origins of residual virus production during effective cART. CXCR4-using viruses might be produced preferentially in patients on cART. Our results also suggest that low-level HIV-1 production in some patients may contribute to persistent immune dysfunction despite cART.
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Affiliation(s)
| | - Pierre Delobel
- INSERM, U563, Toulouse, France
- Université Toulouse III Paul-Sabatier, Centre de Physiopathologie de Toulouse Purpan, Toulouse, France
- CHU Toulouse, Hôpital Purpan, Service des Maladies Infectieuses et Tropicales, Toulouse, France
| | - Michelle Cazabat
- INSERM, U563, Toulouse, France
- CHU Toulouse, Hôpital Purpan, Laboratoire de Virologie, Toulouse, France
| | - Martine Dubois
- INSERM, U563, Toulouse, France
- CHU Toulouse, Hôpital Purpan, Laboratoire de Virologie, Toulouse, France
| | | | - Stéphanie Raymond
- INSERM, U563, Toulouse, France
- Université Toulouse III Paul-Sabatier, Centre de Physiopathologie de Toulouse Purpan, Toulouse, France
- CHU Toulouse, Hôpital Purpan, Laboratoire de Virologie, Toulouse, France
| | - Christophe Pasquier
- INSERM, U563, Toulouse, France
- Université Toulouse III Paul-Sabatier, Centre de Physiopathologie de Toulouse Purpan, Toulouse, France
- CHU Toulouse, Hôpital Purpan, Laboratoire de Virologie, Toulouse, France
| | - Bruno Marchou
- Université Toulouse III Paul-Sabatier, Centre de Physiopathologie de Toulouse Purpan, Toulouse, France
- CHU Toulouse, Hôpital Purpan, Service des Maladies Infectieuses et Tropicales, Toulouse, France
| | - Patrice Massip
- Université Toulouse III Paul-Sabatier, Centre de Physiopathologie de Toulouse Purpan, Toulouse, France
- CHU Toulouse, Hôpital Purpan, Service des Maladies Infectieuses et Tropicales, Toulouse, France
| | - Jacques Izopet
- INSERM, U563, Toulouse, France
- Université Toulouse III Paul-Sabatier, Centre de Physiopathologie de Toulouse Purpan, Toulouse, France
- CHU Toulouse, Hôpital Purpan, Laboratoire de Virologie, Toulouse, France
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119
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Abstract
There is an intense interplay between HIV and the immune system, and the literature is replete with studies describing various immunological phenomena associated with HIV infection. Many of these phenomena seem too broad in scope to be attributable either to HIV-infected cells or to the HIV-specific immune response. Recently, a more fundamental understanding of how HIV affects various T cells and T cell compartments has emerged. This review covers the role of immune activation in HIV immunopathogenesis, how that activation could be mediated directly by HIV replicating within and damaging the gut mucosal barrier, how HIV affects multiple T cell functions and phenotypes, and how chronic HIV replication induces immune modulatory pathways to negatively regulate certain functions in HIV-specific T cells.
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Affiliation(s)
- Daniel C Douek
- Human Immunology Section, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
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120
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Bains I, Thiébaut R, Yates AJ, Callard R. Quantifying thymic export: combining models of naive T cell proliferation and TCR excision circle dynamics gives an explicit measure of thymic output. THE JOURNAL OF IMMUNOLOGY 2009; 183:4329-36. [PMID: 19734223 DOI: 10.4049/jimmunol.0900743] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Understanding T cell homeostasis requires knowledge of the export rate of new T cells from the thymus, a rate that has been surprisingly difficult to estimate. TCR excision circle (TREC) content has been used as a proxy for thymic export, but this quantity is influenced by cell division and loss of naive T cells and is not a direct measure of thymic export. We present in this study a method for quantifying thymic export in humans by combining two simple mathematical models. One uses Ki67 data to calculate the rate of peripheral naive T cell production, whereas the other tracks the dynamics of TRECs. Combining these models allows the contributions of the thymus and cell division to the daily production rate of T cells to be disentangled. The method is illustrated with published data on Ki67 expression and TRECs within naive CD4+ T cells in healthy individuals. We obtain a quantitative estimate for thymic export as a function of age from birth to 20 years. The export rate of T cells from the thymus follows three distinct phases, as follows: an increase from birth to a peak at 1 year, followed by rapid involution until approximately 8 years, and then a more gradual decline until 20 years. The rate of involution shown by our model is compatible with independent estimates of thymic function predicted by thymic epithelial space. Our method allows nonintrusive estimation of thymic output on an individual basis and may provide a means of assessing the role of the thymus in diseases such as HIV.
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Affiliation(s)
- Iren Bains
- Immunobiology Unit, Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, United Kingdom.
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121
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122
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Abstract
Abstract
In this issue of Blood, Clave and colleagues explore the impact of acute GVHD on thymic recovery following hematopoietic stem cell transplantation and begin to address the mechanism by which alloreactivity may impair thymic function in humans.
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123
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Lorenzi AR, Morgan TA, Anderson A, Catterall J, Patterson AM, Foster HE, Isaacs JD. Thymic function in juvenile idiopathic arthritis. Ann Rheum Dis 2009; 68:983-90. [PMID: 18628282 PMCID: PMC2674551 DOI: 10.1136/ard.2008.088112] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/01/2008] [Indexed: 01/04/2023]
Abstract
OBJECTIVE Thymic function declines exponentially with age. Impaired thymic function has been associated with autoimmune disease in adults but has never been formally assessed in childhood autoimmunity. Therefore, thymic function in children with the autoimmune disease juvenile idiopathic arthritis (JIA) was determined. METHODS Thymic function was measured in 70 children and young adults with JIA (age range 2.1-30.8 (median 10.4)) and 110 healthy age-matched controls using four independent assays. T cell receptor excision circles (WBLogTREC/ml) and the proportion of CD4(+) CD45RA(+)CD31(+) T cells (representing recent thymic emigrants; %RTEs) were quantified and intrathymic proliferation measured by calculating the alphaTREC/SigmabetaTREC ratio. Lastly, regulatory T cells (T(Reg)) of thymic origin (CD4(+)FOXP3(+)) were quantified in peripheral blood to assess the ability of the thymus in JIA to generate this T cell subset. RESULTS Thymic function was equivalent by all four parameters in JIA when compared with the control population. Furthermore, there was no consistent effect of JIA subtype on thymic function, although intrathymic proliferation was higher in the small rheumatoid factor (RF)(+) polyarticular group. There were no significant effects of disease-modifying antirheumatic drugs (DMARDs) or oral corticosteroids on thymic function, although those with the worst prognostic ILAR (International League of Associations for Rheumatology) subtypes were also those most likely to be on a DMARD. CONCLUSIONS It is demonstrated that children and young adults with JIA, unlike adults with autoimmune diseases, have thymic function that is comparable with that of healthy controls. The varied pathologies represented by the term "JIA" suggest this observation may not be disease specific and raises interesting questions about the aetiology of thymic impairment in adult autoimmunity.
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Affiliation(s)
- A R Lorenzi
- Institute of Cellular Medicine, Newcastle University, Newcastle-upon-Tyne, UK
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124
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Anz D, Thaler R, Stephan N, Waibler Z, Trauscheid MJ, Scholz C, Kalinke U, Barchet W, Endres S, Bourquin C. Activation of melanoma differentiation-associated gene 5 causes rapid involution of the thymus. THE JOURNAL OF IMMUNOLOGY 2009; 182:6044-50. [PMID: 19414755 DOI: 10.4049/jimmunol.0803809] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
In the course of infection, the detection of pathogen-associated molecular patterns by specialized pattern recognition receptors in the host leads to activation of the innate immune system. Whereas the subsequent induction of adaptive immune responses in secondary lymphoid organs is well described, little is known about the effects of pathogen-associated molecular pattern-induced activation on primary lymphoid organs. Here we show that activation of innate immunity through the virus-sensing melanoma differentiation-associated gene 5 (MDA-5) receptor causes a rapid involution of the thymus. We observed a strong decrease in thymic cellularity associated with characteristic alterations in thymic subpopulations and microanatomy. In contrast, immune stimulation with potent TLR agonists did not lead to thymic involution or induce changes in thymic subpopulations, demonstrating that thymic pathology is not a general consequence of innate immune activation. We determined that suppression of thymocyte proliferation and enhanced apoptosis are the essential cellular mechanisms involved in the decrease in thymic size upon MDA-5 activation. Further, thymic involution critically depended on type I IFN. Strikingly however, no direct action of type I IFN on thymocytes was required, given that the decrease in thymic size was still observed in mice with a selective deletion of the type I IFN receptor on T cells. All changes observed were self-limiting, given that cessation of MDA-5 activation led to a rapid recovery of thymic size. We show for the first time that the in vivo activation of the virus-sensing MDA-5 receptor leads to a rapid and reversible involution of the thymus.
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Affiliation(s)
- David Anz
- Division of Clinical Pharmacology, University of Munich, Munich, Germany
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125
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Morrhaye G, Kermani H, Legros JJ, Baron F, Beguin Y, Moutschen M, Cheynier R, Martens HJ, Geenen V. Impact of growth hormone (GH) deficiency and GH replacement upon thymus function in adult patients. PLoS One 2009; 4:e5668. [PMID: 19479077 PMCID: PMC2682582 DOI: 10.1371/journal.pone.0005668] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2009] [Accepted: 04/27/2009] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Despite age-related adipose involution, T cell generation in the thymus (thymopoiesis) is maintained beyond puberty in adults. In rodents, growth hormone (GH), insulin-like growth factor-1 (IGF-1), and GH secretagogues reverse age-related changes in thymus cytoarchitecture and increase thymopoiesis. GH administration also enhances thymic mass and function in HIV-infected patients. Until now, thymic function has not been investigated in adult GH deficiency (AGHD). The objective of this clinical study was to evaluate thymic function in AGHD, as well as the repercussion upon thymopoiesis of GH treatment for restoration of GH/IGF-1 physiological levels. METHODOLOGY/PRINCIPAL FINDINGS Twenty-two patients with documented AGHD were enrolled in this study. The following parameters were measured: plasma IGF-1 concentrations, signal-joint T-cell receptor excision circle (sjTREC) frequency, and sj/beta TREC ratio. Analyses were performed at three time points: firstly on GH treatment at maintenance dose, secondly one month after GH withdrawal, and thirdly one month after GH resumption. After 1-month interruption of GH treatment, both plasma IGF-1 concentrations and sjTREC frequency were decreased (p<0.001). Decreases in IGF-1 and sjTREC levels were correlated (r = 0.61, p<0.01). There was also a decrease in intrathymic T cell proliferation as indicated by the reduced sj/beta TREC ratio (p<0.01). One month after reintroduction of GH treatment, IGF-1 concentration and sjTREC frequency regained a level equivalent to the one before GH withdrawal. The sj/beta TREC ratio also increased with GH resumption, but did not return to the level measured before GH withdrawal. CONCLUSIONS In patients with AGHD under GH treatment, GH withdrawal decreases thymic T cell output, as well as intrathymic T cell proliferation. These parameters of thymus function are completely or partially restored one month after GH resumption. These data indicate that the functional integrity of the somatotrope GH/IGF-1 axis is important for the maintenance of a normal thymus function in human adults. TRIAL REGISTRATION ClinicalTrials.gov NTC00601419.
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Affiliation(s)
- Gabriel Morrhaye
- University of Liege Center of Immunology, Laboratory of Immunoendocrinology, Institute of Pathology CHU-B23, Liege-Sart Tilman, Belgium
| | - Hamid Kermani
- University of Liege Center of Immunology, Laboratory of Immunoendocrinology, Institute of Pathology CHU-B23, Liege-Sart Tilman, Belgium
| | - Jean-Jacques Legros
- University of Liege Center of Immunology, Laboratory of Immunoendocrinology, Institute of Pathology CHU-B23, Liege-Sart Tilman, Belgium
| | - Frederic Baron
- University of Liege, Division of Hematology, CHU-B35, Liege-Sart Tilman, Belgium
| | - Yves Beguin
- University of Liege, Division of Hematology, CHU-B35, Liege-Sart Tilman, Belgium
| | - Michel Moutschen
- University of Liege, Division of Immunodeficiencies and Infectious Diseases, CHU-B35, Liege-Sart Tilman, Belgium
| | - Remi Cheynier
- Institut Pasteur, Département de Virologie, Paris, France
| | - Henri J. Martens
- University of Liege Center of Immunology, Laboratory of Immunoendocrinology, Institute of Pathology CHU-B23, Liege-Sart Tilman, Belgium
- * E-mail:
| | - Vincent Geenen
- University of Liege Center of Immunology, Laboratory of Immunoendocrinology, Institute of Pathology CHU-B23, Liege-Sart Tilman, Belgium
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126
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Bazdar DA, Kalinowska M, Sieg SF. Interleukin-7 receptor signaling is deficient in CD4+ T cells from HIV-infected persons and is inversely associated with aging. J Infect Dis 2009; 199:1019-28. [PMID: 19239367 DOI: 10.1086/597210] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Loss of interleukin-7 (IL-2) receptor expression has been described in T lymphocytes from persons with human immunodeficiency virus (HIV) infection, potentially contributing to perturbations in T cell homeostasis. We investigated IL-7 receptor signaling by measuring signal transducer and activator of transcription 5 (STAT5) phosphorylation in CD4+ T cell subsets from HIV-infected persons. We determined that CD45RA- memory cell subsets (both CD27+ and CD27-) displayed the most robust immediate responses to IL-7, whereas naive CD4+ T cells sustained the signal most efficiently. Memory CD4+ T cells with a terminal phenotype (CD45RA+CD27-) responded poorly to IL-7 stimulation. Defects in signaling were observed in cells from viremic HIV-infected persons and were especially pronounced in CD45RA-CD27- memory subset. Although CD127 expression was diminished for T cells from HIV-infected persons, it was not directly related to IL-7 receptor signaling function. Instead, age was inversely related to IL-7 signaling in cells from both HIV-infected viremic subjects and healthy control subjects. Thus, HIV infection results in impaired IL-7 responsiveness, especially in memory CD4+ T cells, and this defect is likely compounded by aging.
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Affiliation(s)
- Douglas A Bazdar
- Division of Infectious Diseases and HIV Medicine, Department of Medicine, Case Western Reserve University, and University Hospitals, Cleveland, Ohio 44106, USA
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127
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Westrop SJ, Qazi NA, Pido-Lopez J, Nelson MR, Gazzard B, Gotch FM, Imami N. Transient nature of long-term nonprogression and broad virus-specific proliferative T-cell responses with sustained thymic output in HIV-1 controllers. PLoS One 2009; 4:e5474. [PMID: 19434236 PMCID: PMC2677159 DOI: 10.1371/journal.pone.0005474] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2009] [Accepted: 03/30/2009] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND HIV-1(+) individuals who, without therapy, conserve cellular anti-HIV-1 responses, present with high, stable CD4(+) T-cell numbers, and control viral replication, facilitate analysis of atypical viro-immunopathology. In the absence of universal definition, immune function in such HIV controllers remains an indication of non-progression. METHODOLOGY/PRINCIPAL FINDINGS CD4 T-cell responses to a number of HIV-1 proteins and peptide pools were assessed by IFN-gamma ELISpot and lymphoproliferative assays in HIV controllers and chronic progressors. Thymic output was assessed by sjTRECs levels. Follow-up of 41 HIV-1(+) individuals originally identified as "Long-term non-progressors" in 1996 according to clinical criteria, and longitudinal analysis of two HIV controllers over 22 years, was also performed. HIV controllers exhibited substantial IFN-gamma producing and proliferative HIV-1-specific CD4 T-cell responses to both recombinant proteins and peptide pools of Tat, Rev, Nef, Gag and Env, demonstrating functional processing and presentation. Conversely, HIV-specific T-cell responses were limited to IFN-gamma production in chronic progressors. Additionally, thymic output was approximately 19 fold higher in HIV controllers than in age-matched chronic progressors. Follow-up of 41 HIV-1(+) patients identified as LTNP in 1996 revealed the transitory characteristics of this status. IFN-gamma production and proliferative T-cell function also declines in 2 HIV controllers over 22 years. CONCLUSIONS Although increased thymic output and anti-HIV-1 T-cell responses are observed in HIV controllers compared to chronic progressors, the nature of nonprogressor/controller status appears to be transitory.
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Affiliation(s)
- Samantha J. Westrop
- Department of Immunology, Imperial College London, Chelsea & Westminster Hospital, London, United Kingdom
| | - Nadeem A. Qazi
- Department of HIV/GU Medicine, Imperial College London, Chelsea & Westminster Hospital, London, United Kingdom
| | - Jeffrey Pido-Lopez
- Department of Immunology, Imperial College London, Chelsea & Westminster Hospital, London, United Kingdom
| | - Mark R. Nelson
- Department of HIV/GU Medicine, Imperial College London, Chelsea & Westminster Hospital, London, United Kingdom
| | - Brian Gazzard
- Department of HIV/GU Medicine, Imperial College London, Chelsea & Westminster Hospital, London, United Kingdom
| | - Frances M. Gotch
- Department of Immunology, Imperial College London, Chelsea & Westminster Hospital, London, United Kingdom
| | - Nesrina Imami
- Department of Immunology, Imperial College London, Chelsea & Westminster Hospital, London, United Kingdom
- * E-mail:
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128
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Acute graft-versus-host disease transiently impairs thymic output in young patients after allogeneic hematopoietic stem cell transplantation. Blood 2009; 113:6477-84. [PMID: 19258596 DOI: 10.1182/blood-2008-09-176594] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Long-term T-cell reconstitution after hematopoietic stem cell transplantation (HSCT) is dependent on patient thymic function and affected by graft-versus-host disease (GVHD). To assess the impact of acute GVHD (aGVHD) on thymic function, we followed a cohort of 93 patients who received HSCT from a human histocompatibility leukocyte antigen-identical sibling, mainly for hematologic malignancies. Thymic output was measured by signal-joint T-cell receptor excision circles (sjTREC) real-time polymerase chain reaction. Absolute sjTREC number was lower at 6 months in patients with aGVHD (P = .014), associated with lower absolute counts of naive CD4 T cells at 6 and 12 months (P = .04 and .02), and persistent abnormalities in T-cell repertoire diversity. Age and aGVHD affected thymic function independently in multivariate analysis. In patients less than 25 years of age, thymic function recovered almost totally at 1 year. As a marker of thymocyte proliferation, we quantified the betaTREC generated during the T-cell receptor beta-chain recombination, in a group of 20 age-matched patients. Mean betaTREC level was reduced at 6 months in patients with aGVHD, indicating an impact on early thymic differentiation rather than on intrathymic proliferation. These data show that aGVHD or its treatment has a transient impact on thymic function in younger patients in the first months after HSCT.
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129
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Aw D, Silva AB, Palmer DB. Is thymocyte development functional in the aged? Aging (Albany NY) 2009; 1:146-53. [PMID: 20157506 PMCID: PMC2806005 DOI: 10.18632/aging.100027] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2009] [Accepted: 02/10/2009] [Indexed: 01/09/2023]
Abstract
T cells are an
integral part of a functional immune system with the majority being produced
in the thymus. Of all the changes related to immunosenescence, regression of the thymus is
considered one of the most universally recognised alterations. Despite the reduction of
thymic size, there is evidence to suggest that T cell output is still
present into old age, albeit much diminished; leading to the assumption
that thymocyte development is normal. However, current data suggests that
recent thymic emigrant from the aged thymus are functionally less
responsive, giving rise to the possibility that the generation of
naïve T cell may be intrinsically impaired in the elderly. In light of
these findings we discuss the evidence that suggest aged T cells may be
flawed even before exiting to the periphery and could contribute to the
age-associated decline in immune function.
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Affiliation(s)
- Danielle Aw
- Infection & Immunity and Genes & Development Group, Department of Veterinary Basic Sciences, Royal Veterinary College, UK
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130
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Abstract
Infection of humans by the human immunodeficiency virus (HIV) causes a progressive, multifactorial impairment of the immune system eventually leading to the acquired immunodeficiency syndrome (AIDS). No cure or vaccine exists yet against HIV infection. More worrisome is the fact that despite having identified HIV as the cause of the AIDS, we still do not understand what pathogenic mechanisms lead to the debacle of the immune system. In this review we consider the extent and the limits of our knowledge of HIV pathogenesis, and how this knowledge may be used to design preventive and therapeutic approaches.
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Affiliation(s)
- A Boasso
- Department of Immunology, Faculty of Medicine, Imperial College, Chelsea and Westminster Hospital, London, UK
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131
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Dulude G, Cheynier R, Gauchat D, Abdallah A, Kettaf N, Sékaly RP, Gratton S. The magnitude of thymic output is genetically determined through controlled intrathymic precursor T cell proliferation. THE JOURNAL OF IMMUNOLOGY 2008; 181:7818-24. [PMID: 19017971 DOI: 10.4049/jimmunol.181.11.7818] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The thymus plays a crucial role in providing the immune system with naive T cells showing a diverse TCR repertoire. Whereas the diversity of thymic production is mainly ensured by TCR rearrangement at both the TRA and TRB loci, the number of cells reaching the double-positive differentiation stage defines the extent of thymic output. A quantitative analysis of TCR excision circles (TREC; signal-joint TRECs and DJbetaTRECs) produced at different stages of thymopoiesis was performed in nine laboratory mouse strains. The results clearly demonstrate that the magnitude of thymic output is directly proportional to the extent of proliferation in the double-negative 4 thymocyte subset. Strikingly, intrathymic precursor T cell proliferation was found to be strain dependent, thus suggesting a genetic regulation of thymic output. The inherited character of thymic output was further confirmed by the transmission of the phenotype in a recessive fashion in F(1) progeny of the different parental strains. Our results provide the first demonstration of the genetic regulation of thymic output.
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Affiliation(s)
- Gaël Dulude
- Laboratoire d'Immunologie, Centre de Recherches du Centre Hospitalier de l'Université Montréal, Saint-Luc, Montréal, Québec, Canada
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132
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Démoulins T, Abdallah A, Kettaf N, Baron ML, Gerarduzzi C, Gauchat D, Gratton S, Sékaly RP. Reversible blockade of thymic output: an inherent part of TLR ligand-mediated immune response. THE JOURNAL OF IMMUNOLOGY 2008; 181:6757-69. [PMID: 18981093 DOI: 10.4049/jimmunol.181.10.6757] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
TLRs constitute a first set of sensors that detect viral nucleic acids including dsRNA which triggers TLR3. We report the early, direct, and detrimental effect of polyinosine-polycytidilic acid treatment on T cell development. Inhibition of thymopoiesis was targeted to several thymocyte subpopulations. First, both a blockade of the double negative (DN)1-DN2 transition and a severe down-regulation of DN3-DN4 thymocyte proliferation were observed. In addition, an important decrease in the absolute numbers of double-positive thymocytes, concomitant with an increase in frequencies of apoptotic cells in this population were shown. This inhibition of thymopoiesis resulted in a reduced thymic output, as evidenced by a drop of the absolute numbers of naive T cells and TCR excision circles levels. The decrease in thymic cellularity and defects in thymic development were severely reduced, but not completely abolished in IFN-alpha/betaR(-/-) mice, showing a direct contribution of type I IFNs, known to be massively up-regulated in viral infections, to the inhibition of T cell development. Strikingly, the TCR repertoire in treated mice was biased toward shorter CDR3 lengths as a result of a decreased expression of TdT and Rag2. However, thymic integrity remained intact since thymopoiesis was restored both quantitatively and qualitatively 14 days after the cessation of polyinosine-polycytidilic acid treatment. These results demonstrate a novel immunomodulatory role for virally encoded TLR ligands and RNA sensors; they further illustrate the diversity of mechanisms that viruses use to interfere with the development of a pathogen-specific immune responses.
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Affiliation(s)
- Thomas Démoulins
- Laboratoire d'Immunologie, Centre de Recherches du Centre Hospitalier de l'Université de Montréal, Saint-Luc, Canada
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Westrop SJ, Grageda N, Imami N. Novel approach to recognition of predicted HIV-1 Gag B3501-restricted CD8 T-cell epitopes by HLA-B3501(+) patients: confirmation by quantitative ELISpot analyses and characterisation using multimers. J Immunol Methods 2008; 341:76-85. [PMID: 19056394 DOI: 10.1016/j.jim.2008.11.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Revised: 10/30/2008] [Accepted: 11/03/2008] [Indexed: 01/01/2023]
Abstract
Exploring the intricacies of CD8(+) T-cell epitope recognition using emerging technologies to combine assessment of affinity, phenotype and resulting polyfunctional efficacy advances our understanding of HIV-1 immunopathogenesis and disease progression. Complexities within T-cell antigen recognition, such as epitope:MHC binding, stability and affinity, appear to influence the distinction between protective and ineffective anti-HIV-1 immune responses, which are thought to govern rate of disease progression. This study utilises the novel ProImmune REVEAL and ProVE(R) technology of rapid peptide synthesis, binding and affinity assays, and pentamer synthesis in conjunction with flow cytometry and simultaneous assessment of multiple CD8(+) T-cell effector functions in response to HLA-B3501-restricted HIV-1 Gag peptides, to discover new T-cell epitopes. The predicted HLA-B3501-restricted peptides, HPVHAGPIA and YPLTSLRSL, and relevant pentamers were used in parallel to validate T-cell epitopes on clinical HIV-1(+) samples, confirming correlation between the expected superior immunogenicity of newly discovered epitopes and the ex vivo T-cell response. Such a platform should be employed in prophylactic and therapeutic vaccine settings.
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Affiliation(s)
- Samantha J Westrop
- Department of Immunology, Imperial College London, Chelsea and Westminster Hospital, 369, Fulham Road, London SW10 9NH, United Kingdom
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Herasimtschuk AA, Westrop SJ, Moyle GJ, Downey JS, Imami N. Effects of recombinant human growth hormone on HIV-1-specific T-cell responses, thymic output and proviral DNA in patients on HAART: 48-week follow-up. JOURNAL OF IMMUNE BASED THERAPIES AND VACCINES 2008; 6:7. [PMID: 18976455 PMCID: PMC2613878 DOI: 10.1186/1476-8518-6-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/25/2008] [Accepted: 10/31/2008] [Indexed: 01/05/2023]
Abstract
BACKGROUND Efficacious immune-based therapy in treated chronic HIV-1 infection requires the induction of virus-specific CD4+ T cells and subsequent maturation and maintenance of specific memory CD8+ T cells. Concomitant daily administration of recombinant human growth hormone (rhGH) with highly active antiretroviral therapy (HAART) was used in chronically infected patients with lipodystrophy in an attempt to reconstitute these virus-specific T-cell responses. METHODS Individuals with chronic HIV-1 infection on HAART were enrolled on a randomized, double-blinded, placebo-controlled study to receive rhGH therapy. We assessed HIV-1-specific proliferative CD4+ and interferon-gamma (IFN-gamma)-producing CD8+ T-cell responses, quantified thymic output and proviral HIV-1 DNA at the following time points: baseline; after 12 weeks of rhGH therapy; at 24 weeks, after randomization into three groups [placebo weeks 12-24 (Group A), alternate-day dosing weeks 12-24 (Group B), and twice-per-week dosing weeks 12-24 (Group C)]; and at 48 weeks after all patients had received HAART alone for the final 24 weeks. RESULTS We found significant increases in both proliferative CD4+ and IFN-gamma-producing CD8+ HIV-1-specific T-cell responses after daily administration of rhGH. This increase was focused on HIV-1 Gag-specific T-cell responses. Following subsequent randomisation into different dosing regimens, HIV-1-specific proliferative CD4+ T-cell responses declined in patients receiving less frequent dosing of rhGH, while virus-specific IFN-gamma-producing CD8+ T-cell responses were maintained for longer periods of time. There was no significant change in thymic output and the cell-associated HIV-1 DNA remained stable in most patients. An increased anti-HIV-1 Nef-specific CD4+ T-cell proliferative response was correlated to a decrease in proviral load, and an increased HIV-1 Gag-specific IFN-gamma-producing CD8+ T-cell response correlated with an increase in proviral load. CONCLUSION The implication of these data is that daily dosing of rhGH with HAART, in addition to improving HIV-1-associated lipodystrophy, may reverse some of the T-lymphocyte dysfunction seen in most treated HIV-1-positive patients, in a dose-dependent manner. Such immune-based therapeutic strategies used in treated, chronic HIV-1 infection may enable the induction of virus-specific CD4+ T cells essential for the subsequent 'kick-start' and expansion of virus-specific CD8+ T cells. TRIAL REGISTRATION GH in Lipoatrophy IMP22350.
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Affiliation(s)
- Anna A Herasimtschuk
- Department of Immunology, Imperial College London, Chelsea and Westminster Hospital, 369 Fulham Road, London, SW10 9NH, UK
| | - Samantha J Westrop
- Department of Immunology, Imperial College London, Chelsea and Westminster Hospital, 369 Fulham Road, London, SW10 9NH, UK
| | - Graeme J Moyle
- Department of HIV/GU Medicine, Imperial College London, Chelsea and Westminster Hospital, 369 Fulham Road, London, SW10 9NH, UK
| | - Jocelyn S Downey
- Department of Immunology, Imperial College London, Chelsea and Westminster Hospital, 369 Fulham Road, London, SW10 9NH, UK
| | - Nesrina Imami
- Department of Immunology, Imperial College London, Chelsea and Westminster Hospital, 369 Fulham Road, London, SW10 9NH, UK
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135
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HIV-1 Nef protein expression in human CD34+ progenitors impairs the differentiation of an early T/NK cell precursor. Virology 2008; 377:207-15. [PMID: 18555888 DOI: 10.1016/j.virol.2008.04.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2008] [Revised: 03/25/2008] [Accepted: 04/14/2008] [Indexed: 12/30/2022]
Abstract
HIV-1 impairs the production of T cells, through mechanisms that are still unknown. Here, we investigated the effect of the expression of HIV-1 Nef on the T-cell potential of human hematopoietic CD34(+) precursors. Those progenitors were transduced by using lentiviral vectors expressing Nef and cultured on OP9-DL1 cells allowing the differentiation of T cell from human hematopoietic precursors. We demonstrate that Nef impairs the generation of a CD3epsilon(+)CD5(+) CD1a(+) precursor stage that has initiated a D-J rearrangement of the TCRbeta locus. Onward stages of T-cell development were also affected with a quantitative reduction of CD4(+) intraCD3epsilon(+) Immature single positive cells (ISP), Double Positive (DP) CD4(+)CD8(+) TCRalphabeta T cells and CD56(+) NK cells. But B cell production was not affected. Limiting dilution analyses demonstrated a significant reduction in the frequency of T/NK progenitors among Nef-expressing CD34(+) cells. Altogether, these data demonstrate that Nef interferes with the differentiation of a primitive lymphoid human precursor with a T/NK potential.
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136
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Abstract
Much effort has been devoted to the design of vaccines that induce adaptive cellular immunity, in particular CD8+ T cells, which have a central role in the host response to viral infections and cancers. To date, however, the development of effective T cell vaccines remains elusive. This is due, in part, to the lack of clearly defined correlates of protection and the inherent difficulties that hinder full characterization of the determinants of successful T cell immunity in humans. Recent data from the disparate fields of infectious disease and tumor immunology have converged, with an emphasis on the functional attributes of individual antigen-specific T cell clonotypes, to provide a better understanding of CD8+ T cell efficacy. This new knowledge paves the way to the design of more effective T cell vaccines and highlights the importance of comprehensive immunomonitoring.
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Affiliation(s)
- Victor Appay
- Cellular Immunology Laboratory, Institut Nationale de la Santé et de la Recherche Médicale U543, Avenir Group, Hôpital Pitié-Salpêtrière, Université Pierre et Marie Curie Paris 06, 91 Boulevard de l'hôpital, 75013 Paris, France.
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137
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Napolitano LA, Schmidt D, Gotway MB, Ameli N, Filbert EL, Ng MM, Clor JL, Epling L, Sinclair E, Baum PD, Li K, Killian ML, Bacchetti P, McCune JM. Growth hormone enhances thymic function in HIV-1-infected adults. J Clin Invest 2008; 118:1085-98. [PMID: 18292808 DOI: 10.1172/jci32830] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2007] [Accepted: 01/02/2008] [Indexed: 01/05/2023] Open
Abstract
Growth hormone (GH) is an underappreciated but important regulator of T cell development that can reverse age-related declines in thymopoiesis in rodents. Here, we report findings of a prospective randomized study examining the effects of GH on the immune system of HIV-1-infected adults. GH treatment was associated with increased thymic mass. In addition, GH treatment enhanced thymic output, as measured by both the frequency of T cell receptor rearrangement excision circles in circulating T cells and the numbers of circulating naive and total CD4(+) T cells. These findings provide compelling evidence that GH induces de novo T cell production and may, accordingly, facilitate CD4(+) T cell recovery in HIV-1-infected adults. Further, these randomized, prospective data have shown that thymic involution can be pharmacologically reversed in humans, suggesting that immune-based therapies could be used to enhance thymopoiesis in immunodeficient individuals.
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Affiliation(s)
- Laura A Napolitano
- Gladstone Institute of Virology and Immunology, San Francisco, California 94158, USA.
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138
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Sparse production but preferential incorporation of recently produced naive T cells in the human peripheral pool. Proc Natl Acad Sci U S A 2008; 105:6115-20. [PMID: 18420820 DOI: 10.1073/pnas.0709713105] [Citation(s) in RCA: 152] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
In mice, recent thymic emigrants (RTEs) make up a large part of the naïve T cell pool and have been suggested to be a distinct short-lived pool. In humans, however, the life span and number of RTEs are unknown. Although (2)H(2)O labeling in young mice showed high thymic-dependent daily naïve T cell production, long term up- and down-labeling with (2)H(2)O in human adults revealed a low daily production of naïve T cells. Using mathematical modeling, we estimated human naïve CD4 and CD8 T cell half-lives of 4.2 and 6.5 years, respectively, whereas memory CD4 and CD8 T cells had half-lives of 0.4 and 0.7 year. The estimated half-life of recently produced naïve T cells was much longer than these average half-lives. Thus, our data are incompatible with a substantial short-lived RTE population in human adults and suggest that the few naïve T cells that are newly produced are preferentially incorporated in the peripheral pool.
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139
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Venturi V, Price DA, Douek DC, Davenport MP. The molecular basis for public T-cell responses? Nat Rev Immunol 2008; 8:231-8. [PMID: 18301425 DOI: 10.1038/nri2260] [Citation(s) in RCA: 257] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Public T-cell responses, in which T cells bearing identical T-cell receptors (TCRs) are observed to dominate the response to the same antigenic epitope in multiple individuals, have long been a focus of immune T-cell repertoire studies. However, the mechanism that enables the survival of a specific TCR from the diverse repertoire produced in the thymus through to its involvement in a public immune response remains unclear. In this Opinion article, we propose that the frequency of production of T cells bearing different TCRs during recombination has an important role in the sharing of TCRs in an immune response, with variable levels of 'convergent recombination' driving production frequencies.
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Affiliation(s)
- Vanessa Venturi
- Complex Systems Biology Group, Centre for Vascular Research, University of New South Wales, Kensington New South Wales 2052, Australia
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140
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141
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142
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Evans VA, Cameron PU, Lewin SR. Human thymic dendritic cells: Regulators of T cell development in health and HIV-1 infection. Clin Immunol 2008; 126:1-12. [DOI: 10.1016/j.clim.2007.08.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2007] [Revised: 08/20/2007] [Accepted: 08/20/2007] [Indexed: 12/12/2022]
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143
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Human T cell reconstitution in DiGeorge syndrome and HIV-1 infection. Semin Immunol 2007; 19:297-309. [PMID: 18035553 DOI: 10.1016/j.smim.2007.10.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2007] [Accepted: 10/02/2007] [Indexed: 01/19/2023]
Abstract
The thymus is essential for proper development and maintenance of a broad T cell repertoire capable of recognizing a wide-range of foreign antigens. Recent advances in multicolor flow cytometry, non-invasive imaging techniques, and molecular assessments of thymic function have enabled a more comprehensive characterization of human thymic output in clinical settings than in the past. These techniques have been particularly valuable in monitoring human T cells after therapeutic thymic grafting for complete DiGeorge syndrome and during HIV-1 infection and AIDS. By defining the degree and mechanisms of T cell reconstitution in these settings, clinical investigators and primary caregivers have been able to better diagnose, treat and care for individuals with congenital or acquired immune deficiencies associated with loss of thymic function.
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144
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Williams KM, Hakim FT, Gress RE. T cell immune reconstitution following lymphodepletion. Semin Immunol 2007; 19:318-30. [PMID: 18023361 DOI: 10.1016/j.smim.2007.10.004] [Citation(s) in RCA: 249] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2007] [Accepted: 10/02/2007] [Indexed: 12/14/2022]
Abstract
T cell reconstitution following lymphopenia from chemotherapy or stem cell transplant is often slow and incompetent, contributing to the development of infectious diseases, relapse, and graft-versus-host disease. This is due to the fact that de novo T cell production is impaired following cytoreductive regimens. T cells can be generated from two pathways: (1) thymus derived through active thymopoiesis and (2) peripherally expanded clones through homeostatic proliferation. During recovery from lymphopenia, the thymic pathway is commonly compromised in adults and T cells rely upon peripheral expansion to restore T cell numbers. This homeostatic proliferation exploits the high cytokine levels following lymphopenia to rapidly generate T cells in the periphery. Moreover, this early peripheral expansion of T cells can also be driven by exogenous antigen. This results in loss of T cell repertoire diversity and may predispose to auto- or allo-immunity. Alternatively, the high homeostatic proliferation following lymphopenia may facilitate expansion of anti-tumor immunity. Murine and human studies have provided insight into the cytokine and cellular regulators of these two pathways of T cell generation and the disparate portraits of T cell immunity created through robust thymopoiesis or peripheral expansion following lymphopenia. This insight has permitted the manipulation of the immune system to maximize anti-tumor immunity through lymphopenia and led to an appreciation of mechanisms that underlie graft versus host disease.
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Affiliation(s)
- Kirsten M Williams
- Experimental Transplantation and Immunology Branch, National Cancer Institute, NIH, Bethesda, MD 20892, USA
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145
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Vranjkovic A, Crawley AM, Gee K, Kumar A, Angel JB. IL-7 decreases IL-7 receptor alpha (CD127) expression and induces the shedding of CD127 by human CD8+ T cells. Int Immunol 2007; 19:1329-39. [PMID: 17956896 DOI: 10.1093/intimm/dxm102] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
IL-7 receptor alpha (CD127) signaling is essential for T-cell development and regulation of naive and memory T-cell homeostasis. Fewer CD8(+) T cells from HIV-infected patients express CD127 compared with healthy individuals, suggesting that specific host and/or viral factors regulate IL-7 receptor expression. Factors relevant to HIV infection that could potentially decrease CD127 expression on human CD8(+) T cells and the mechanisms by which this occurs were therefore evaluated. IL-7, but not HIV gp120, IL-1-beta, IL-6, IL-10, IL-13, transforming growth factor-beta or tumor necrosis factor-alpha, reduced CD127-surface expression and did so without altering CD127 mRNA expression. Furthermore, IL-7 did not increase the amount of cytoplasmic CD127 in CD8(+) T cells. Interestingly, IL-7 induced the shedding of CD127 from CD8(+) T cells, suggesting a mechanism that may contribute to the increased concentration of CD127 in the plasma of HIV(+) individuals, a novel finding reported here. Naive CD8(+) T cells are more sensitive to IL-7 that mediated the down-regulation of CD127, suggesting that these effects may have particular significance early in T-cell life cycle. Since CD127 down-regulation may be an important contributor to HIV-associated T-cell dysfunction, determining the mechanism thereof may prove to be of considerable significance.
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146
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Abstract
Aging is associated clinically with increases in the frequency and severity of infectious diseases and an increased incidence of cancer, chronic inflammatory disorders and autoimmunity. These age-associated immune dysfunctions are the consequence of declines in both the generation of new naïve T and B lymphocytes and the functional competence of memory populations. These alterations collectively are termed immunosenescence.
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Affiliation(s)
- F T Hakim
- Experimental Transplantation and Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
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147
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Pratesi C, Simonelli C, Zanussi S, Talamini R, Bortolin MT, Tedeschi R, Marus A, Caffau C, Michieli M, Tirelli U, De Paoli P. Recent thymic emigrants in lymphoma patients with and without human immunodeficiency virus infection candidates for autologous peripheral stem cell transplantation. Clin Exp Immunol 2007; 151:101-9. [PMID: 17931391 DOI: 10.1111/j.1365-2249.2007.03516.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Signal joint T cell receptor excision circles (sjTRECs) have been reported as a clinical marker to measure the potential for recovery of the immune system after immunosuppressive treatments. The aim of this study was to investigate the thymic regenerative potential in 55 human immunodeficiency virus (HIV)-1 infected (HIV(+)) and non-infected (HIV(-)) lymphoma patients, candidates for autologous stem cell transplantation (ASCT). Moreover, the possible associations between sjTRECs and other immunological and clinical parameters were examined. SjTRECs levels in peripheral blood mononuclear cells (PBMCs) were quantified by real-time polymerase chain reaction and T lymphocyte subsets were analysed by flow cytometry. Our data showed that sjTRECs were reduced in lymphoma patients compared to healthy controls, although a weak significant association between low sjTRECs levels and increasing age was maintained [odds ratio (OR) = 4.00; 95% confidence interval (CI) 1.09-17.17]. We found that different chemotherapeutic treatments seem to induce similar effects on the thymic reservoir, independently from their intensity (type and number of cycles of previous chemotherapy). Results from multivariate models including adjustment for patients' sex, type of lymphoma and type of chemotherapy showed that thymic output was independent from HIV infection (OR, 0.95; 95% CI 0.20-4.48). SjTRECs levels correlated with naive T cell subsets in overall lymphoma patients and after stratification by HIV infection (r > 0.37). HIV replication should be maximally suppressed to properly evaluate thymic output by sjTREC markers. Our results suggested that de novo T cell generation is maintained partially in pretreated recurrent lymphoma patients, candidates for ASCT, and could contribute to restore the immune function after transplantation.
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Affiliation(s)
- C Pratesi
- Microbiology, Immunology and Virology Unit, Centro di Riferimento Oncologico, IRCCS, Aviano, Italy
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148
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Salemi M, Burkhardt BR, Gray RR, Ghaffari G, Sleasman JW, Goodenow MM. Phylodynamics of HIV-1 in lymphoid and non-lymphoid tissues reveals a central role for the thymus in emergence of CXCR4-using quasispecies. PLoS One 2007; 2:e950. [PMID: 17895991 PMCID: PMC1978532 DOI: 10.1371/journal.pone.0000950] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2007] [Accepted: 09/06/2007] [Indexed: 01/04/2023] Open
Abstract
Background During HIV-1 infection coreceptor switch from CCR5- (R5)- to CXCR4 (X4)-using viruses is associated with disease progression. X4 strains of HIV-1 are highly cytopathic to immature thymocytes. Virtually no studies have evaluated the HIV-1 quasispecies present in vivo within thymic and lymphoid tissues or the evolutionary relationship between R5 and X4 viruses in tissues and peripheral blood. Methodology/Principal Findings High-resolution phylodynamic analysis was applied to virus envelope quasispecies in longitudinal peripheral blood mononuclear cells (PBMCs) and lymphoid and non-lymphoid tissues collected post mortem from therapy naïve children with AIDS. There were three major findings. First, continued evolution of R5 viruses in PBMCs, spleen and lymph nodes involved multiple bottlenecks, independent of coreceptor switch, resulting in fitter quasispecies driven by positive selection. Second, evolution of X4 strains appeared to be a sequential process requiring the initial fixation of positively selected mutations in V1-V2 and C2 domains of R5 variants before the emergence of high charge V3 X4 variants. Third, R5 viruses persisted after the emergence of CXCR4-using strains, which were found predominantly but not exclusively in the thymus. Conclusions/Significance Our data indicate that the evolution of X4 strains is a multi-step, temporally structured process and that the thymus may play an important role in the evolution/amplification of coreceptor variants. Development of new therapeutic protocols targeting virus in the thymus could be important to control HIV-1 infection prior to advanced disease.
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Affiliation(s)
- Marco Salemi
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, Florida, United States of America
- * To whom correspondence should be addressed. E-mail: (MS); (MG)
| | - Brant R. Burkhardt
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, Florida, United States of America
| | - Rebecca R. Gray
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, Florida, United States of America
- Department of Anthropology, University of Florida, Gainesville, Florida, United States of America
| | - Guity Ghaffari
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, Florida, United States of America
- Department of Pediatrics, Division of Immunology, Rheumatology, and Infectious Diseases, University of Florida, Gainesville, Florida, United States of America
| | - John W. Sleasman
- Department of Pediatrics, Division of Allergy, Immunology, and Rheumatology, University of South Florida and All Children's Hospital, St. Petersburg, Florida, United States of America
| | - Maureen M. Goodenow
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, Florida, United States of America
- Department of Pediatrics, Division of Immunology, Rheumatology, and Infectious Diseases, University of Florida, Gainesville, Florida, United States of America
- * To whom correspondence should be addressed. E-mail: (MS); (MG)
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149
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Gautier D, Beq S, Cortesão CS, Sousa AE, Cheynier R. Efficient thymopoiesis contributes to the maintenance of peripheral CD4 T cells during chronic human immunodeficiency virus type 2 infection. J Virol 2007; 81:12685-8. [PMID: 17804512 PMCID: PMC2168967 DOI: 10.1128/jvi.01131-07] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Human immunodeficiency virus type 2 (HIV-2) infection leads to a lifelong asymptomatic period in the majority of patients. Even in patients with progressive disease, a slow CD4 count decline characterizes the chronic phase of HIV-2 infection, suggesting that peripheral T-cell homeostasis is controlled better following HIV-2 infection than following HIV-1 infection. Herein we showed that, in contrast to HIV-1-infected patients, HIV-2-infected patients demonstrate enhanced thymic function compared to age-matched healthy individuals. The correlation between higher thymic production and lower CD4 T-cell loss in these patients suggests that efficient thymopoiesis is implicated in the long-lasting maintenance of CD4 T-cell counts in HIV-2 disease.
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Affiliation(s)
- David Gautier
- Département de Virologie, Institut Pasteur, 28 rue du Dr Roux, 75015, Paris, France
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150
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Fritsch Fredin M, Elgbratt K, Svensson D, Jansson L, Melgar S, Hultgren Hörnquist E. Dextran sulfate sodium-induced colitis generates a transient thymic involution--impact on thymocyte subsets. Scand J Immunol 2007; 65:421-9. [PMID: 17444952 DOI: 10.1111/j.1365-3083.2007.01923.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
One of the most widely used animal models for inflammatory bowel disease (IBD) is the dextran sulfate sodium (DSS)-induced colitis. We have previously reported that 5 days administration of DSS in C57Bl/6J mice induces a colonic inflammation that progresses into chronicity after DSS removal, whereas in BALB/cJ mice the inflammation resolves within 4 weeks post-DSS. Here we show that both thymic size and thymocyte numbers dramatically decreased in the acute phase of inflammation in C57Bl/6 mice, 7 days after DSS withdrawal. Mature, CD4(+) and CD8(+) single positive (SP) CD69(lo) CD62L(hi) thymocytes were enriched in these mice, accompanied by a major decrease in the number of immature double positive (DP) thymocytes. However, the different maturation stages within the DP thymocyte subset were unchanged between healthy and inflamed C57Bl/6J mice. Interestingly, as the inflammation progressed into the chronic phase, the thymus recovered and 2 weeks after the acute inflammatory phase all the thymic parameters investigated in this study were restored to normal. In contrast, BALB/cJ mice only develop mild thymic alterations. Nevertheless, we found that within the double negative (DN) thymocytes an increased frequency and also total numbers of CD44(+) CD25(-) (DN1) cells correlated with the severity of colitis, and that the frequency of CD44(-) CD25(-) (DN4) thymocytes decreased proportionally in the acute phase in BALB/cJ mice. Our observations suggest that the thymic effects are intimately connected to the intestinal inflammatory response in colitis regardless of the inflammatory stimuli.
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Affiliation(s)
- M Fritsch Fredin
- Department of Integrative Pharmacology, AstraZeneca R&D Mölndal, Mölndal, Sweden
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