RESUMO
Mechanisms of tumor immune escape are quite diverse and require specific approaches for their exploration in syngeneic tumor models. In several human malignancies, galectin-9 (gal-9) is suspected to contribute to the immune escape. However, in contrast with what has been done for the infiltrating cells, the contribution of gal-9 produced by malignant cells has never been demonstrated in an animal model. Therefore, we derived isogenic clones-either positive or negative for gal-9-from the MB49 murine bladder carcinoma cell line. A progressive and consistent reduction of tumor growth was observed when gal-9-KO cells were subjected to serial transplantations into syngeneic mice. In contrast, tumor growth was unaffected during parallel serial transplantations into nude mice, thus linking tumor inhibition to the enhancement of the immune response against gal-9-KO tumors. This stronger immune response was at least in part explained by changing patterns of response to interferon-γ. One consistent change was a more abundant production of CXCL10, a major inflammatory factor whose production is often induced by interferon-γ. Overall, these observations demonstrate for the first time that serial transplantation into syngeneic mice can be a valuable experimental approach for the exploration of novel mechanisms of tumor immune escape.
Assuntos
Quimiocina CXCL10/genética , Galectinas/genética , Interferon gama/genética , Evasão Tumoral/genética , Neoplasias da Bexiga Urinária/genética , Animais , Linhagem Celular Tumoral , Modelos Animais de Doenças , Humanos , Interferon gama/imunologia , Camundongos , Camundongos Nus , Transplante Isogênico , Evasão Tumoral/imunologia , Neoplasias da Bexiga Urinária/imunologia , Neoplasias da Bexiga Urinária/patologiaRESUMO
OBJECTIVES: Recombinant Human IL-7 (rhIL-7) therapy allows reconstituting systemic and tissue-associated CD4 T-cell populations in HIV-infected poor immunological responder (PIR) patients. However, in-vitro studies suggest that the impact of rhIL-7 treatment on HIV-DNA loads in vivo remains questionable. DESIGN: We assessed the dynamics of circulating HIV-DNA loads in IL-7-treated HIV-infected PIR individuals. METHODS: Forty-one rhIL-7-treated and 16 control participants from the INSPIRE-3 clinical trial were included. Participants received three weekly subcutaneous injections of rhIL-7. HIV-DNA was quantified by nested quantitative PCR in white blood cells sampled at D0, D28 and M3 and expressed as per milliliters and per CD4 T-cell. Changes in HIV-DNA loads in the CD4 compartment at M3 were confirmed on sorted CD4 cells. RESULTS: Together with rhIL-7-induced T-cell expansion, we observed a significant raise in both infected cell frequencies and counts during the first 28 days of follow-up. During this period, HIV-DNA load per CD4 T-cell also increased, to a lower extent. Three months post-therapy, both the frequencies and counts of infected cells diminished in blood as compared with D28 but remained significantly higher than before IL-7 therapy. In contrast, infection frequencies strongly diminished within CD4 cells, reaching slightly but significantly lower levels than at baseline. CONCLUSION: rhIL-7 treatment initially drives an expansion of HIV reservoir in PIR patients by D28. This expansion is probably not only because of infected cell proliferation, but also to possible enhanced neoinfection, despite highly active antiretroviral therapy. In contrast, subsequent reduction in HIV-DNA load per CD4 T-cell argues for partial elimination of infected cells between D28 and M3.
Assuntos
Antirretrovirais/administração & dosagem , Infecções por HIV/tratamento farmacológico , Infecções por HIV/virologia , HIV/isolamento & purificação , Fatores Imunológicos/administração & dosagem , Interleucina-7/administração & dosagem , Carga Viral , Adulto , Linfócitos T CD4-Positivos/virologia , DNA Viral/análise , Feminino , HIV/genética , Humanos , Injeções Subcutâneas , Masculino , Pessoa de Meia-Idade , Resultado do TratamentoRESUMO
Exogenous Interleukin-7 (IL-7), in supplement to antiretroviral therapy, leads to a substantial increase of all CD4+ T cell subsets in HIV-1 infected patients. However, the quantitative contribution of the several potential mechanisms of action of IL-7 is unknown. We have performed a mathematical analysis of repeated measurements of total and naive CD4+ T cells and their Ki67 expression from HIV-1 infected patients involved in three phase I/II studies (Nâ=â53 patients). We show that, besides a transient increase of peripheral proliferation, IL-7 exerts additional effects that play a significant role in CD4+ T cell dynamics up to 52 weeks. A decrease of the loss rate of the total CD4+ T cell is the most probable explanation. If this effect could be maintained during repeated administration of IL-7, our simulation study shows that such a strategy may allow maintaining CD4+ T cell counts above 500 cells/µL with 4 cycles or fewer over a period of two years. This in-depth analysis of clinical data revealed the potential for IL-7 to achieve sustained CD4+ T cell restoration with limited IL-7 exposure in HIV-1 infected patients with immune failure despite antiretroviral therapy.
Assuntos
Linfócitos T CD4-Positivos/imunologia , Infecções por HIV/imunologia , HIV-1/imunologia , Interleucina-7/imunologia , Modelos Imunológicos , Células Cultivadas , Simulação por Computador , Infecções por HIV/patologia , Humanos , Antígeno Ki-67/imunologiaRESUMO
OBJECTIVES: Thymus dysfunction characterizes human/simian immunodeficiency virus (SIV) infections and contributes to physiopathology. However, both the mechanisms involved in thymic dysfunction and its precise timing remain unknown. We here analyzed thymic function during acute SIV infection in rhesus macaques. DESIGN AND METHODS: Rhesus macaques were intravenously infected with SIVmac251 and bled every 2/3 days or necropsied at different early time points postinfection. Naive T-cell counts were followed by flow cytometry and their T-cell receptor excision circle content evaluated by qPCR. Thymic chemokines were quantified by reverse transcription-qPCR and localized by in-situ hybridization in thymuses collected at necropsy. Thymic interferon alpha (IFN-α) subtype production was quantified by reverse transcription-qPCR combined to heteroduplex tracking assay. The effect of thymic IFN-α subtypes was tested on sorted triple negative thymocytes cultured on OP9-hDL1 cells. RESULTS: A reduced intrathymic proliferation history characterizes T cells produced during the first weeks of infection. Moreover, we evidenced a profound alteration of both chemokines and IFN-α subtypes transcriptional patterns in SIV-infected thymuses. Finally, we showed that IFN-α subtypes produced in the infected thymuses inhibit thymocyte proliferation, still preserving their differentiation capacity. CONCLUSION: Thymopoiesis is deeply impacted from the first days of SIV infection. Reduced thymocyte proliferation - a time-consuming process - together with modified chemokine networks is consistent with thymocyte differentiation speed-up. This may transiently enhance thymic output, thus increasing naive T-cell counts and diversity and the immune competence of the host. Nonetheless, long-lasting modification of thymic physiology may lead to thymic exhaustion, as observed in late primary HIV infection.
Assuntos
Quimiocinas/metabolismo , Interferon-alfa/metabolismo , Síndrome de Imunodeficiência Adquirida dos Símios/fisiopatologia , Vírus da Imunodeficiência Símia , Linfócitos T/metabolismo , Timo/fisiopatologia , Animais , Contagem de Linfócito CD4 , Citometria de Fluxo , Hibridização In Situ , Macaca mulatta , Reação em Cadeia da Polimerase , RNA Mensageiro/metabolismo , Receptores de Antígenos de Linfócitos T/metabolismoRESUMO
Despite antiretroviral therapy (ART), some HIV-infected persons maintain lower than normal CD4(+) T-cell counts in peripheral blood and in the gut mucosa. This incomplete immune restoration is associated with higher levels of immune activation manifested by high systemic levels of biomarkers, including sCD14 and D-dimer, that are independent predictors of morbidity and mortality in HIV infection. In this 12-week, single-arm, open-label study, we tested the efficacy of IL-7 adjunctive therapy on T-cell reconstitution in peripheral blood and gut mucosa in 23 ART suppressed HIV-infected patients with incomplete CD4(+) T-cell recovery, using one cycle (consisting of three subcutaneous injections) of recombinant human IL-7 (r-hIL-7) at 20 µg/kg. IL-7 administration led to increases of both CD4(+) and CD8(+) T-cells in peripheral blood, and importantly an expansion of T-cells expressing the gut homing integrin α4ß7. Participants who underwent rectosigmoid biopsies at study baseline and after treatment had T-cell increases in the gut mucosa measured by both flow cytometry and immunohistochemistry. IL-7 therapy also resulted in apparent improvement in gut barrier integrity as measured by decreased neutrophil infiltration in the rectosigmoid lamina propria 12 weeks after IL-7 administration. This was also accompanied by decreased TNF and increased FOXP3 expression in the lamina propria. Plasma levels of sCD14 and D-dimer, indicative of systemic inflammation, decreased after r-hIL-7. Increases of colonic mucosal T-cells correlated strongly with the decreased systemic levels of sCD14, the LPS coreceptor - a marker of monocyte activation. Furthermore, the proportion of inflammatory monocytes expressing CCR2 was decreased, as was the basal IL-1ß production of peripheral blood monocytes. These data suggest that administration of r-hIL-7 improves the gut mucosal abnormalities of chronic HIV infection and attenuates the systemic inflammatory and coagulation abnormalities that have been linked to it.
Assuntos
Colite/tratamento farmacológico , Colo/imunologia , Infecções por HIV/tratamento farmacológico , Interleucina-7/administração & dosagem , Mucosa Intestinal/imunologia , Adulto , Relação CD4-CD8 , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD4-Positivos/metabolismo , Linfócitos T CD4-Positivos/patologia , Linfócitos T CD8-Positivos/imunologia , Linfócitos T CD8-Positivos/metabolismo , Linfócitos T CD8-Positivos/patologia , Doença Crônica , Colite/imunologia , Colite/metabolismo , Colite/patologia , Colo/metabolismo , Colo/patologia , Feminino , Produtos de Degradação da Fibrina e do Fibrinogênio/imunologia , Produtos de Degradação da Fibrina e do Fibrinogênio/metabolismo , Infecções por HIV/sangue , Infecções por HIV/imunologia , Infecções por HIV/patologia , Humanos , Inflamação/tratamento farmacológico , Inflamação/imunologia , Inflamação/metabolismo , Inflamação/patologia , Integrinas/biossíntese , Integrinas/imunologia , Mucosa Intestinal/metabolismo , Mucosa Intestinal/patologia , Receptores de Lipopolissacarídeos/sangue , Receptores de Lipopolissacarídeos/imunologia , Masculino , Pessoa de Meia-Idade , Monócitos/imunologia , Monócitos/metabolismo , Infiltração de Neutrófilos/efeitos dos fármacos , Neutrófilos/imunologia , Neutrófilos/patologiaRESUMO
The heterogeneity of human regulatory T cells (Tregs) may explain the discrepancies between studies on Tregs in physiology and pathology. Contrasting effects of IL-7 on the expansion and survival of human Tregs were reported. Therefore, we investigated the effects of IL-7 on the phenotype and function of well-characterized populations of human Tregs. We show that IL-7 signals via the CD127 receptor on naive, memory, and activated memory Tregs sorted from the blood of healthy donors, but it does not affect their proliferation. In contrast, IL-7 affects their suppressive capacities differently. This effect was modest on naive Tregs but was dramatic (90%) on memory Tregs. We provide evidence that IL-7 exerts a synergistic effect through downmodulation of the ectoenzyme CD39, which converts ATP to ADP/AMP, and an increase in ATP receptor P2X7. Both effects lead to an increase in the ATP-mediated effect, tipping the balance to favor Th17 conversion. Using an IL-7 therapeutic study, we show that IL-7 exerts the same effects in vitro and in vivo in HIV-infected individuals. Globally, our data show that IL-7 negatively regulates Tregs and contributes to increase the number of tools that may affect Treg function in pathology.
Assuntos
Trifosfato de Adenosina/metabolismo , Antígenos CD/metabolismo , Apirase/metabolismo , Memória Imunológica/imunologia , Interleucina-7/metabolismo , Linfócitos T Reguladores/metabolismo , Trifosfato de Adenosina/imunologia , Antígenos CD/imunologia , Apirase/imunologia , Separação Celular , Citometria de Fluxo , Humanos , Interleucina-7/imunologia , Fenótipo , Reação em Cadeia da Polimerase em Tempo Real , Transdução de Sinais/imunologia , Linfócitos T Reguladores/imunologiaRESUMO
Human soluble interleukin-7 receptor (sIL7R)α circulates in high molar excess compared with IL-7, but its biology remains unclear. We demonstrate that sIL7Rα has moderate affinity for IL-7 but does not bind thymic stromal lymphopoietin. Functionally, sIL7Rα competes with cell-associated IL-7 receptor to diminish excessive IL-7 consumption and, thus, enhances the bioactivity of IL-7 when the cytokine is limited, as it is presumed to be in vivo. IL-7 signaling in the presence of sIL7Rα also diminishes expression of CD95 and suppressor of cytokine signaling 1, both regulatory molecules. Murine models confirm diminished consumption of IL-7 in the presence of sIL7Rα and also demonstrate a potentiating effect of sIL7Rα on IL-7-mediated homeostatic expansion and experimental autoimmune encephalomyelitis exacerbation. In multiple sclerosis and several other autoimmune diseases, IL7R genotype influences susceptibility. We measured increased sIL7Rα levels, as well as increased IL-7 levels, in multiple sclerosis patients with the predisposing IL7R genotype, consistent with diminished IL-7 consumption in vivo. This work demonstrates that sIL7Rα potentiates IL-7 bioactivity and provides a basis to explain the increased risk of autoimmunity observed in individuals with genotype-induced elevations of sIL7Rα.
Assuntos
Autoimunidade , Interleucina-7/imunologia , Esclerose Múltipla/genética , Polimorfismo Genético , Receptores de Interleucina-7/genética , Adolescente , Adulto , Idoso , Animais , Linhagem Celular , Citocinas/metabolismo , Encefalomielite Autoimune Experimental/genética , Encefalomielite Autoimune Experimental/imunologia , Feminino , Genótipo , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Pessoa de Meia-Idade , Esclerose Múltipla/imunologia , Receptores de Interleucina-7/imunologia , Transdução de Sinais , Linfócitos T/imunologia , Linfócitos T/metabolismo , Adulto JovemRESUMO
Interferon alpha (IFNα) therapy, despite good efficacy in curing HCV infection, leads to major side effects, in particular inducement of a strong peripheral T-cell lymphocytopenia. We here analyze the early consequences of IFNα therapy on both thymic function and peripheral T-cell homeostasis in patients in the acute or chronic phase of HCV-infection as well as in HIV/HCV co-infected patients. The evolution of T-cell subsets and T-cell homeostasis were estimated by flow cytometry while thymic function was measured through quantification of T-cell receptor excision circles (TREC) and estimation of intrathymic precursor T-cell proliferation during the first four months following the initiation of IFNα therapy. Beginning with the first month of therapy, a profound lymphocytopenia was observed for all T-cell subsets, including naïve T-cells and recent thymic emigrants (RTE), associated with inhibition of intrathymic precursor T-cell proliferation. Interleukin (IL)-7 plasma concentration rapidly dropped while lymphocytopenia progressed. This was neither a consequence of higher consumption of the cytokine nor due to its neutralization by soluble CD127. Decrease in IL-7 plasma concentration under IFNα therapy correlated with the decline in HCV viral load, thymic activity and RTE concentration in blood. These data demonstrate that IFNα-based therapy rapidly impacts on thymopoiesis and, consequently, perturbs T-cell homeostasis. Such a side effect might be detrimental for the continuation of IFNα therapy and may lead to an increased level of infectious risk, in particular in HIV/HCV co-infected patients. Altogether, this study suggests the therapeutic potential of IL-7 in the maintenance of peripheral T-cell homeostasis in IFNα-treated patients.
Assuntos
Antivirais/uso terapêutico , Hepatite C/tratamento farmacológico , Hepatite C/imunologia , Fatores Imunológicos/uso terapêutico , Interferon-alfa/uso terapêutico , Timo/imunologia , Adulto , Antivirais/efeitos adversos , Antivirais/farmacologia , Coinfecção/tratamento farmacológico , Coinfecção/imunologia , Coinfecção/metabolismo , Feminino , Infecções por HIV/imunologia , Infecções por HIV/metabolismo , Hepatite C/metabolismo , Humanos , Fatores Imunológicos/efeitos adversos , Fatores Imunológicos/farmacologia , Interferon-alfa/efeitos adversos , Interferon-alfa/farmacologia , Interleucina-7/sangue , Linfopenia/induzido quimicamente , Masculino , Pessoa de Meia-Idade , Subpopulações de Linfócitos T/efeitos dos fármacos , Subpopulações de Linfócitos T/imunologia , Timo/efeitos dos fármacosRESUMO
Although great effort is being expended in the development of cancer immunotherapies, it is surprising that global lymphopenia and its various dimensions are not being systematically assessed in cancer patients. The incident pathologies associated with various immunosuppressed conditions such as those found in HIV infection have taught us that measuring various T cell populations including CD4 provides the clinician with a reliable measure for gauging the risk of cancer and opportunistic infections. Importantly, recent data emphasize the key link between lymphocyte T cell counts and overall survival in cancer patients receiving chemotherapy. Treatment of immunocompromised patients with interleukin-7 (IL-7), a critical growth and homeostatic factor for T cells, has been shown to produce a compelling profile of T cell reconstitution. The clinical results of this investigational therapy confirm data obtained from numerous preclinical studies and demonstrate the long-term stability of this immune reconstitution, not only on CD4 but also on CD8 T cells, involving recent thymic emigrants as well as naive, memory, and central memory T cells. Furthermore, IL-7 therapy also contributes to restoration of a broadened diversity of the T cell repertoire as well as to migration of these cells to lymph nodes and tissues. All these properties support the initiation of new clinical studies aimed at reconstituting the immune system of cancer patients before or immediately after chemotherapy in order to demonstrate a potentially profound increase in overall survival.
Assuntos
Imunoterapia , Interleucina-7/uso terapêutico , Linfopenia/imunologia , Linfopenia/prevenção & controle , Neoplasias/tratamento farmacológico , Animais , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Homeostase/efeitos dos fármacos , Humanos , Imunoterapia/tendências , Linfopenia/etiologia , Linfopenia/mortalidade , Neoplasias/imunologia , Neoplasias/mortalidade , Melhoria de Qualidade , Análise de Sobrevida , Subpopulações de Linfócitos T/efeitos dos fármacos , Subpopulações de Linfócitos T/imunologia , Linfócitos T/efeitos dos fármacos , Linfócitos T/imunologiaRESUMO
BACKGROUND: Elevated serum interleukin 7 (IL-7) levels are observed in lymphopenic conditions, including idiopathic CD4 lymphopenia (ICL), which is characterized by CD4 lymphopenia in the absence of human immunodeficiency virus infection or other known immunodeficiency. METHODS: To test whether defective IL-7 signaling could be an etiologic or contributing factor in ICL, peripheral blood mononuclear cells from patients with ICL (median CD4 T-cell count, 160 cells/µL) and healthy controls (median CD4 T-cell count, 582 cells/µL) were evaluated for expression of IL-7Rα chain (CD127) and intracellular phosphorylated STAT-5 (a marker of γc cytokine signaling) after cytokine stimulation. Gene expression was analyzed by real-time polymerase chain reaction following IL-7 stimulation. RESULTS: The percentage of CD4+CD127+ T cells was lower in patients with ICL, compared with controls (P < .001). Lower levels of STAT-5 phosphorylation after IL-7 stimulation were observed in both CD4 and CD8 T cells from patients with ICL, compared with controls (P < .001 and P = .017, respectively), that inversely correlated in CD4 T cells with serum IL-7 levels (r = -0.734, P = .013). Destabilization of p27(kip1), a critical step for IL-7-induced T-cell cycling, was decreased in patients with ICL, compared with controls (P = .004), after IL-7 stimulation. CONCLUSIONS: These data suggest that diminished responsiveness to IL-7 in CD4 and CD8 T cells during ICL may be contributing to the dysregulation of T-cell homeostasis.
Assuntos
Interleucina-7/sangue , Linfócitos T/imunologia , T-Linfocitopenia Idiopática CD4-Positiva/imunologia , Adulto , Feminino , Humanos , Interleucina-7/genética , Interleucina-7/imunologia , Leucócitos Mononucleares/metabolismo , Contagem de Linfócitos , Masculino , Pessoa de Meia-Idade , Fosforilação , Reação em Cadeia da Polimerase em Tempo Real , Receptores de Interleucina-7/sangue , Receptores de Interleucina-7/genética , Receptores de Interleucina-7/imunologia , Fator de Transcrição STAT5/genética , Fator de Transcrição STAT5/metabolismo , T-Linfocitopenia Idiopática CD4-Positiva/metabolismo , Regulação para Cima , Proteína X Associada a bcl-2/genética , Proteína X Associada a bcl-2/metabolismoRESUMO
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.
Assuntos
Antivirais/uso terapêutico , Interferon-alfa/uso terapêutico , Interleucina-7/uso terapêutico , Linfopenia/tratamento farmacológico , Síndrome de Imunodeficiência Adquirida dos Símios/tratamento farmacológico , Vírus da Imunodeficiência Símia/imunologia , Linfócitos T Citotóxicos/imunologia , Animais , Citometria de Fluxo , Humanos , Memória Imunológica , Ativação Linfocitária/efeitos dos fármacos , Linfopenia/induzido quimicamente , Macaca mulatta , Síndrome de Imunodeficiência Adquirida dos Símios/imunologia , Linfócitos T/citologia , Linfócitos T/efeitos dos fármacos , Linfócitos T/imunologia , Carga ViralRESUMO
IL-7 is a crucial cytokine for T cell hematopoiesis and peripheral homeostasis which by signaling through its receptor alpha chain (CD127) is essential for inducing T cell proliferation and survival. Since the specific CD127 alpha chain is found in a soluble state (sCD127) and at a high level in plasma (ng/mL), it is important to develop a sensitive and reliable assay in order to investigate the potential role of this receptor in the regulation of IL-7 physiologic, physipathologic and therapeutic effects. We here report a fully validated method to measure sCD127 in human and simian plasma using a method based on ELISA MSD technology. We demonstrate that sCD127 is detectable at various levels in the plasma of healthy humans as well as in that of healthy Rhesus and Cynomolgus macaques (106.72, 205.26 and 366.95 ng/mL respectively). Moreover, as opposed to the sCD25/IL-2 tandem, we demonstrate that IL-7 treatment has no impact on sCD127 plasma concentration in patients infected by HIV.
Assuntos
Antivirais/uso terapêutico , Ensaio de Imunoadsorção Enzimática , Infecções por HIV/tratamento farmacológico , Subunidade alfa de Receptor de Interleucina-7/sangue , Interleucina-7/uso terapêutico , Síndrome de Imunodeficiência Adquirida dos Símios/imunologia , Animais , Calibragem , Ensaio de Imunoadsorção Enzimática/normas , Infecções por HIV/imunologia , Humanos , Macaca fascicularis , Macaca mulatta , Proteínas Recombinantes/uso terapêutico , Reprodutibilidade dos TestesRESUMO
Interleukin-7 (IL-7), the principal cytokine implicated in thymopoiesis and peripheral T-cell homeostasis, is presently under evaluation in human diseases characterized by persistent lymphopenia. Unexpectedly, before the eventual IL-7-driven T-cell expansion, all treated patients showed a profound T-cell depletion 24 hours after injection. The current study uses the rhesus macaque model to investigate the mechanisms involved in this IL-7-induced T-cell depletion. We identify a new critical function of IL-7 that induces massive and rapid T-cell migration from the blood into various organs, including lymph nodes, parts of the intestine, and the skin. This homing process was initiated after the induction of chemokine receptor expression by circulating T cells and the production of corresponding chemokines in target organs. Finally, we demonstrate that the IL-7-induced cell cycling is initiated within these organs before T cells migrate back into the bloodstream, indicating that T-cell homing is required for in vivo IL-7 function.
Assuntos
Quimiotaxia de Leucócito/efeitos dos fármacos , Interleucina-7/farmacologia , Linfócitos T/efeitos dos fármacos , Animais , Apoptose/efeitos dos fármacos , Apoptose/imunologia , Proliferação de Células/efeitos dos fármacos , Glicosilação , Injeções , Interleucina-7/administração & dosagem , Interleucina-7/metabolismo , Interleucina-7/fisiologia , Contagem de Linfócitos , Macaca mulatta , Receptores de Quimiocinas/metabolismo , Proteínas Recombinantes/administração & dosagem , Proteínas Recombinantes/farmacologia , Linfócitos T/fisiologia , Fatores de TempoRESUMO
We characterized the localization, phenotype, and some functions of plasmacytoid dendritic cells (pDCs) in the human spleen. pDCs were localized in the marginal zone and the periarteriolar region. Some were also found in the red pulp. pDCs were immature by phenotypic labeling, consistently with their capacity to internalize Dextran in a functional assay. In spleens from HIV-infected patients with thrombocytopenic purpura, these characteristics were unaffected. However, an accumulation of pDCs, but not myeloid dendritic cells (mDCs), was observed in some HIV+ patients, correlating with high proviral loads. Moreover, although undetectable in most HIV- patients, interferon-alpha (IFN-alpha) production was evidenced in situ and by flow cytometry in most HIV+ patients. IFN-alpha was located in the marginal zone. Surprisingly, IFN-alpha colocalized only with few pDCs, but rather with other cells, including T and B lymphocytes, mDCs, and macrophages. Therefore, pDCs accumulated in spleens from HIV+ patients with high proviral loads, but they did not seem to be the main IFN-alpha producers.
Assuntos
Células Dendríticas/fisiologia , Infecções por HIV/imunologia , HIV-1/fisiologia , Interferon-alfa/biossíntese , Baço/imunologia , Terapia Antirretroviral de Alta Atividade , Linfócitos T CD4-Positivos/efeitos dos fármacos , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD4-Positivos/virologia , Doença Crônica , Endocitose , Citometria de Fluxo , Imunofluorescência , Infecções por HIV/tratamento farmacológico , Infecções por HIV/virologia , Humanos , Mediadores da Inflamação/metabolismo , Interferon-alfa/antagonistas & inibidores , FenótipoRESUMO
HIV infection results in CD4+ T cell deficiency, but efficient combination antiretroviral therapy (c-ART) restores T cells and decreases morbidity and mortality. However, immune restoration by c-ART remains variable, and prolonged T cell deficiency remains in a substantial proportion of patients. In a prospective open-label phase I/IIa trial, we evaluated the safety and efficacy of administration of the T cell regulator IL-7. The trial included 13 c-ART-treated HIV-infected patients whose CD4+ cell counts were between 100 and 400 cells/microl and plasma HIV RNA levels were less than 50 copies/ml. Patients received a total of 8 subcutaneous injections of 2 different doses of recombinant human IL-7 (rhIL-7; 3 or 10 microg/kg) 3 times per week over a 16-day period. rhIL-7 was well tolerated and induced a sustained increase of naive and central memory CD4+ and CD8+ T cells. In the highest dose group, 4 patients experienced transient increases in viral replication. However, functional assays showed that the expanded T cells responded to HIV antigen by producing IFN-gamma and/or IL-2. In conclusion, in lymphopenic HIV-infected patients, rhIL-7 therapy induced substantial functional and quantitative changes in T cells for 48 weeks. Therefore, patients may benefit from intermittent therapy with IL-7 in combination with c-ART.
Assuntos
Infecções por HIV/tratamento farmacológico , Infecções por HIV/imunologia , Interleucina-7/uso terapêutico , Linfócitos T/efeitos dos fármacos , Linfócitos T/imunologia , Adulto , Idoso , Contagem de Linfócito CD4 , Relação CD4-CD8 , Ciclo Celular/efeitos dos fármacos , Tolerância a Medicamentos , Infecções por HIV/virologia , HIV-1 , Humanos , Memória Imunológica , Interleucina-7/efeitos adversos , Ativação Linfocitária/efeitos dos fármacos , Linfopenia/tratamento farmacológico , Linfopenia/imunologia , Pessoa de Meia-Idade , Estudos Prospectivos , Proteínas Recombinantes/efeitos adversos , Proteínas Recombinantes/uso terapêutico , Segurança , Linfócitos T/patologiaRESUMO
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.
Assuntos
Linfócitos T CD4-Positivos/imunologia , Infecções por HIV/imunologia , HIV-2 , Timo/imunologia , Adulto , Contagem de Linfócito CD4 , Feminino , HIV-1 , Humanos , Masculino , Pessoa de Meia-Idade , Timo/citologiaRESUMO
Despite efficient antiretroviral therapy (ART), CD4+ T cell counts often remain low in HIV-1-infected patients. This has led to IL-7, a crucial cytokine involved in both thymopoiesis and peripheral T cell homeostasis, being suggested as an additional therapeutic strategy. We investigated whether recombinant simian IL-7-treatment enhanced the T cell renewal initiated by ART in rhesus macaques chronically infected with SIVmac251. Six macaques in the early chronic phase of SIV infection received antiretroviral treatment. Four macaques also received a 3-wk course of IL-7 injections. Viral load was unaffected by IL-7 treatment. IL-7 treatment increased the number of circulating CD4+ and CD8+ memory T cells expressing activation (HLA-DR+, CD25+) and proliferation (Ki-67+) markers. It also increased naive (CD45RAbrightCD62L+) T cell counts by peripheral proliferation and enhanced de novo thymic production. The studied parameters returned to pretreatment values by day 29 after the initiation of treatment, concomitantly to the appearance of anti-IL-7 neutralizing Abs, supporting the need for a nonimmunogenic molecule for human treatment. Thus, IL-7, which increases T cell memory and de novo renewal of naive T cells may have additional benefits in HIV-infected patients receiving ART.
Assuntos
Antivirais/uso terapêutico , Interleucina-7/farmacologia , Síndrome de Imunodeficiência Adquirida dos Símios/tratamento farmacológico , Síndrome de Imunodeficiência Adquirida dos Símios/imunologia , Subpopulações de Linfócitos T/efeitos dos fármacos , Animais , Sequência de Bases , Linfócitos T CD4-Positivos/efeitos dos fármacos , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/efeitos dos fármacos , Linfócitos T CD8-Positivos/imunologia , Proliferação de Células/efeitos dos fármacos , DNA/genética , Humanos , Interleucina-7/imunologia , Ativação Linfocitária/efeitos dos fármacos , Contagem de Linfócitos , Macaca mulatta , Proteínas Recombinantes/imunologia , Proteínas Recombinantes/farmacologia , Síndrome de Imunodeficiência Adquirida dos Símios/genética , Síndrome de Imunodeficiência Adquirida dos Símios/virologia , Subpopulações de Linfócitos T/imunologia , Viremia/tratamento farmacológico , Viremia/imunologia , Viremia/virologiaRESUMO
BACKGROUND: An attenuated immunodeficiency virus has been long considered innocuous. Nevertheless, converging data suggest that low levels of viral replication can still provoke AIDS. Pathogenesis of these attenuated infections is not understood. OBJECTIVES: To determine the pathogenicity of a long-term attenuated infection and to delineate T-cell dynamics during such an infection. METHODS: This is a cross-sectional study of 12 rhesus macaques infected with SIV Delta nef for 8 years. We evaluated apoptosis (annexin V), activation (HLA-DR, Ki67), and newly generated T cells (TCR excision circle: TREC). RESULTS: Infection with SIV Delta nef induced pathological CD4 T-cell depletion after 8 years of infection. Virus replication and CD8 T-cell activation positively correlated with the rate of disease progression. The frequency of TREC within CD8+CD45RA+ cells increased in SIV Delta nef-infected animals compared to age-matched non-infected controls. Moreover, in the cohort of infected animals, TREC+CD45RA+CD4+ T-cell counts correlated strongly with non-progression to AIDS. The animal with the lowest rate of disease progression exhibited a 115-fold increase in TREC+CD45RA+CD4+ T-cell counts compared to age-matched non-infected controls. In contrast, the animal showing the fastest rate of progression to AIDS displayed 600-fold lower TREC+CD45RA+CD4+ T-cell counts compared to age-matched non-infected controls. CONCLUSIONS: Our results suggest that the thymus plays a major role in the pathogenesis of an attenuated SIV infection and that a sustained thymic output could maintain CD4 T-cell homeostasis in the context of low viral loads.
Assuntos
Síndrome de Imunodeficiência Adquirida dos Símios/virologia , Vírus da Imunodeficiência Símia/fisiologia , Animais , Apoptose , Contagem de Linfócito CD4 , Relação CD4-CD8 , Linfócitos T CD8-Positivos , Proliferação de Células , Progressão da Doença , Produtos do Gene nef , Rearranjo Gênico do Linfócito T , Antígenos Comuns de Leucócito/análise , Ativação Linfocitária , Macaca mulatta , Síndrome de Imunodeficiência Adquirida dos Símios/imunologia , Fatores de Tempo , Carga Viral , Replicação ViralRESUMO
IL-7 is a crucial cytokine regulating lymphopoiesis and peripheral T lymphocyte homeostasis. Plasma IL-7 levels increase during HIV infection and, although antiretroviral therapy (ARV therapy) decreases these levels, they fail to return to normal. Immune reconstitution in most ARV-treated patients is only partial. We tested the possibility that the IL-7R system might be affected by ARV drugs. The effects of the antireverse transcriptase AZT and the anti-protease saquinavir on CD3- and CD3+CD28-induced T lymphocyte stimulation, in the presence (or absence) of IL-7, were studied in vitro. Small amounts of the drugs did not interfere with the capacity of IL-7 to stimulate T cell proliferation, but higher concentrations significantly decreased IL-7-induced T cell proliferation both in cells from HIV-infected patients and in cells from healthy donors. IL-7 is known to down-modulate its own receptor on the surface of CD4 and CD8 T lymphocytes in vitro. In CD4 lymphocytes from healthy donors or HIV-infected patients, neither AZT, nor saquinavir, nor a combination of the two, interfered with this property. In contrast, AZT + saquinavir worsened the IL-7-induced down-regulation of CD127 expression by CD8 T cells from HIV-infected patients, while no such effect was observed with CD8 T cells from healthy donors. Our data suggest that, under certain conditions, antiretroviral therapy could interfere with the expression and function of the IL-7/IL-7R system, and more particularly it may affect the CD8-lymphocyte compartment of HIV-infected patients.