RESUMO
Several ß cell antigens recognized by T cells in the non-obese diabetic (NOD) mouse model of type 1 diabetes (T1D) are also T cell targets in the human disease. While numerous antigen-specific therapies prevent diabetes in NOD mice, successful translation of rodent findings to patients has been difficult. A human leucocyte antigen (HLA)-transgenic mouse model incorporating human ß cell-specific T cells might provide a better platform for evaluating antigen-specific therapies. The ability to study such T cells is limited by their low frequency in peripheral blood and the difficulty in obtaining islet-infiltrating T cells from patients. We have worked to overcome this limitation by using lentiviral transduction to 'reprogram' primary human CD8 T cells to express three T cell receptors (TCRs) specific for a peptide derived from the ß cell antigen islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP265-273 ) and recognized in the context of the human class I major histocompatibility complex (MHC) molecule HLA-A2. The TCRs bound peptide/MHC multimers with a range of avidities, but all bound with at least 10-fold lower avidity than the anti-viral TCR used for comparison. One exhibited antigenic recognition promiscuity. The ß cell-specific human CD8 T cells generated by lentiviral transduction with one of the TCRs released interferon (IFN)-γ in response to antigen and exhibited cytotoxic activity against peptide-pulsed target cells. The cells engrafted in HLA-A2-transgenic NOD-scid IL2rγ(null) mice and could be detected in the blood, spleen and pancreas up to 5 weeks post-transfer, suggesting the utility of this approach for the evaluation of T cell-modulatory therapies for T1D and other T cell-mediated autoimmune diseases.
Assuntos
Linfócitos T CD8-Positivos/imunologia , Diabetes Mellitus Tipo 1/imunologia , Vetores Genéticos/genética , Imunoterapia Adotiva/métodos , Células Secretoras de Insulina/imunologia , Lentivirus/genética , Linfócitos T Citotóxicos/imunologia , Animais , Linfócitos T CD8-Positivos/transplante , Sobrevivência Celular , Glucose-6-Fosfatase/imunologia , Antígeno HLA-A2/genética , Antígeno HLA-A2/metabolismo , Humanos , Células Jurkat , Camundongos , Camundongos Endogâmicos NOD , Camundongos Knockout , Camundongos Transgênicos , Fragmentos de Peptídeos/imunologia , Receptores de Antígenos de Linfócitos T/metabolismo , Receptores de Interleucina-2/genética , Linfócitos T Citotóxicos/transplanteRESUMO
The murine immune system is not necessarily identical to it human counterpart, which has led to the construction of humanized mice. The current study analysed whether or not a human immune system contained within the non-obese diabetic (NOD)-Rag1(null) -γ chain(null) (NRG) mouse model was an accurate representation of the original stem cell donor and if multiple mice constructed from the same donor were similar to one another. To that end, lightly irradiated NRG mice were injected intrahepatically on day 1 of life with purified cord blood-derived CD34(+) stem and progenitor cells. Multiple mice were constructed from each cord blood donor. Mice were analysed quarterly for changes in the immune system, and followed for periods up to 12 months post-transplant. Mice from the same donor were compared directly with each other as well as with the original donor. Analyses were performed for immune reconstitution, including flow cytometry, T cell receptor (TCR) and B cell receptor (BCR) spectratyping. It was observed that NRG mice could be 'humanized' long-term using cord blood stem cells, and that animals constructed from the same cord blood donor were nearly identical to one another, but quite different from the original stem cell donor immune system.
Assuntos
Transplante de Células-Tronco de Sangue do Cordão Umbilical , Sistema Imunitário/imunologia , Células-Tronco/imunologia , Animais , Antígenos CD34/metabolismo , Sangue Fetal/citologia , Proteínas de Homeodomínio/genética , Humanos , Camundongos , Camundongos Endogâmicos NOD , Receptores de Antígenos de Linfócitos T/imunologiaRESUMO
SETTING: Publicly funded human immunodeficiency virus (HIV) clinics in Los Angeles County, California, USA. BACKGROUND: HIV-infected persons are a high priority group for targeted testing and treatment for Mycobacterium tuberculosis infection in the United States. OBJECTIVE: To describe rates of isoniazid (INH) initiation and completion among HIV-1 and M. tuberculosis co-infected persons in Los Angeles County. DESIGN: We conducted a cross-sectional study using routinely collected surveillance data from publicly funded HIV clinics. We examined differences in INH treatment initiation and completion between four clinic categories: the three largest clinics (Clinics A, B, and C) and 'Other' clinics (pooled data for the remaining 10 clinics). RESULTS: During 2010-2013, 802 (5.3%) of 15 029 HIV-1-infected persons tested positive for M. tuberculosis infection. INH was initiated in 581 (72.4%) persons, of whom 457 (78.7%) completed treatment. We found significant differences between clinics in terms of treatment initiation (range 59.1-93.4%) and completion (range 58.8-82.3%). Overall, 57% (457/802) of HIV and M. tuberculosis co-infected persons completed the recommended treatment (range across clinics 34.8-76.3%). CONCLUSION: We identified significant gaps in the treatment for M. tuberculosis infection among HIV-infected persons in Los Angeles County. Interventions are needed to improve initiation and completion of treatment for M. tuberculosis infection in this population.
Assuntos
Instituições de Assistência Ambulatorial , Antituberculosos/uso terapêutico , Coinfecção , Infecções por HIV/epidemiologia , Isoniazida/uso terapêutico , Tuberculose/tratamento farmacológico , Adulto , Estudos Transversais , Feminino , Fidelidade a Diretrizes , Infecções por HIV/diagnóstico , Infecções por HIV/virologia , HIV-1/isolamento & purificação , Humanos , Los Angeles/epidemiologia , Masculino , Adesão à Medicação , Pessoa de Meia-Idade , Guias de Prática Clínica como Assunto , Padrões de Prática Médica , Setor Público , Estudos Retrospectivos , Fatores de Tempo , Resultado do Tratamento , Tuberculose/diagnóstico , Tuberculose/epidemiologiaRESUMO
Compounds that can block the CXCR4 chemokine receptor are a promising new class of antiretroviral agents. In these experiments we studied the effect of a modified form of the native stromal cell-derived factor-1 (SDF-1), Met-SDF-1beta. The in vitro susceptibility of two different CXCR4-tropic HIV-1 strains was determined. Antiviral effect was assessed by the reduction of p24 antigen production in PHA-stimulated peripheral blood mononuclear cells with exposure to the modified SDF-1 molecule. The 50% inhibitory concentrations (IC50) were derived from six separate experiments. The IC50 against the two HIV-1 isolates was in 1.0-2.8 microg/ml range for Met-SDF-1beta. Met-SDF-1beta showed synergy to additivity with either zidovudine or nelfinavir at IC75 IC90 and IC95. Additivity was seen when Met-SDF-1beta was combined with efavirenz. No cellular toxicity was observed at the highest concentrations when these agents were used either singly or in combination. This compound is a promising new candidate in a receptor-based approach to HIV-1 infection in conjunction with currently available combination antiretroviral drug therapies.
Assuntos
Fármacos Anti-HIV/farmacologia , Quimiocinas CXC/farmacologia , HIV-1/efeitos dos fármacos , Metionina/análogos & derivados , Metionina/farmacologia , Inibidores da Transcriptase Reversa/farmacologia , Zidovudina/farmacologia , Quimiocina CXCL12 , Interações Medicamentosas , Quimioterapia Combinada , Infecções por HIV/virologia , Humanos , Leucócitos Mononucleares/virologia , Nelfinavir/farmacologiaRESUMO
Chronic inappropriate immune activation is the central defect-driving loss of CD4(+) T helper cells and progression to AIDS in persons with HIV-1 infection, but the mechanisms remain controversial. We examined key regulatory invariant receptor natural killer T (iNKT) cells in the gut, the largest reservoir of lymphocytes and a key arena of HIV-1 pathogenesis. In healthy control persons, the anti-inflammatory CD4(+) iNKT-cell subset predominated over the pro-inflammatory CD4(-) iNKT-cell subset in the gut, but not in the blood, compartment. HIV-1 infection resulted in a preferential loss of this anti-inflammatory CD4(+) iNKT-cell subset within the gut. The degree of loss of the CD4(+) iNKT-cell subset in the gut, but not in the blood, correlated to the systemic immune activation and exhaustion that have been linked to disease progression. These results suggest a potentially important contribution of gut iNKT-cell imbalance in determining the systemic immune activation that is the hallmark of HIV-1 pathogenesis.
Assuntos
Infecções por HIV/imunologia , HIV-1/imunologia , Intestinos/imunologia , Depleção Linfocítica , Células T Matadoras Naturais/imunologia , Adulto , Antígenos CD4/metabolismo , Morte Celular , Progressão da Doença , Humanos , Imunomodulação , Intestinos/virologia , Contagem de Linfócitos , Masculino , Pessoa de Meia-Idade , Células T Matadoras Naturais/virologia , Ativação Viral/imunologia , Adulto JovemAssuntos
Linfócitos T CD8-Positivos/imunologia , Antígenos HIV/imunologia , Infecções por HIV/imunologia , HIV-1/fisiologia , Linfócitos T Citotóxicos/imunologia , Replicação Viral/imunologia , Quimiocinas/fisiologia , Estudos de Coortes , Epitopos/imunologia , Infecções por HIV/virologia , Antígenos HLA/imunologia , Humanos , Interleucina-16/farmacologiaRESUMO
OBJECTIVES: Although multiple methods have been proposed, there is no current gold standard for assessing HIV-1-associated lipodystrophy. METHODS: HIV-1-infected participants were randomly enrolled and surveyed about changes in the abdomen, thigh, cheek and neck areas. Magnetic resonance imaging (MRI) sequences of these sites were obtained. Participants were grouped according to survey results, and the MRI measurements were compared between groups. RESULTS: One hundred participants were included in the study, of whom 79% reported any body fat changes. Persons reporting increased abdominal girth had higher visceral ([mean+/-standard deviation] 142+/-75 vs. 59+/-48 cm2; P<0.0001) and total abdominal adipose tissue than those reporting no change (344+/-119 vs. 201+/-95 cm2; P<0.0001). The amount of localized fat was less for persons reporting sunken cheeks and reduced diameter of the legs compared with those who noted no changes (5.9+/-3.6 vs. 9.3+/-3.8 cm2; P<0.0001, and 35+/-28 vs. 112+/-56 cm2; P<0.0001). Participants reporting increased neck girth had a thicker fat layer in the dorsocervical region compared with those reporting no change (4.0+/-1.8 vs. 2.3+/-1.4 cm; P<0.0002). CONCLUSIONS: MRI is a precise method for rapidly surveying body regions affected by HIV-1-associated lipodystrophy. Our proposed protocol provides a rapid, comprehensive survey of these areas, without the need to combine multiple modalities or to expose subjects to radiation.
Assuntos
Tecido Adiposo/patologia , Infecções por HIV/complicações , Síndrome de Lipodistrofia Associada ao HIV/patologia , Imageamento por Ressonância Magnética/métodos , Gordura Subcutânea/patologia , Adulto , Diagnóstico Diferencial , Feminino , Infecções por HIV/patologia , HIV-1 , Humanos , Masculino , Pessoa de Meia-Idade , Análise de Regressão , Imagem Corporal TotalRESUMO
Viruses encounter changing selective pressures during transmission between hosts, including host-specific immune responses and potentially varying functional demands on specific proteins. The human immunodeficiency virus type 1 Nef protein performs several functions potentially important for successful infection, including immune escape via down-regulation of class I major histocompatibility complex (MHC-I) and direct enhancement of viral infectivity and replication. Nef is also a major target of the host cytotoxic T-lymphocyte (CTL) response. To examine the impact of changing selective pressures on Nef functions following sexual transmission, we analyzed genetic and functional changes in nef clones from six transmission events. Phylogenetic analyses indicated that the diversity of nef was similar in both sources and acutely infected recipients, the patterns of selection across transmission were variable, and regions of Nef associated with distinct functions evolved similarly in sources and recipients. These results weighed against the selection of specific Nef functions by transmission or during acute infection. Measurement of Nef function provided no evidence that the down-regulation of either CD4 or MHC-I was optimized by transmission or during acute infection, although rare nef clones from sources that were impaired in these activities were not detected in recipients. Nef-specific CTL activity was detected as early as 3 weeks after infection and appeared to be an evolutionary force driving the diversification of nef. Despite the change in selective pressure between the source and recipient immune systems and concomitant genetic diversity, the majority of Nef proteins maintained robust abilities to down-regulate MHC-I and CD4. These data suggest that both functions are important for the successful establishment of infection in a new host.
Assuntos
Evolução Molecular , Regulação Viral da Expressão Gênica , Produtos do Gene nef/genética , Produtos do Gene nef/metabolismo , Variação Genética , Infecções por HIV/transmissão , HIV-1/genética , Seleção Genética , Sequência de Aminoácidos , Sequência de Bases , Western Blotting , Antígenos CD4/metabolismo , Citometria de Fluxo , Genes MHC Classe I/fisiologia , Infecções por HIV/metabolismo , Humanos , Funções Verossimilhança , Modelos Genéticos , Dados de Sequência Molecular , Filogenia , Alinhamento de Sequência , Análise de Sequência de DNA , Linfócitos T Citotóxicos/imunologia , Produtos do Gene nef do Vírus da Imunodeficiência HumanaRESUMO
CD8 lymphocytes probably play a key role in the immunologic defense against HIV. The evidence is that they control viral replication by at least two mechanisms: direct antigen-specific cytolysis, which appears to be required for optimal suppression, and release of soluble antiviral factors. New therapeutic strategies are taking into account mechanisms by which the virus may evade CD8 control.
Assuntos
Linfócitos T CD8-Positivos/imunologia , Infecções por HIV/imunologia , Quimiocinas/imunologia , Progressão da Doença , Infecções por HIV/sangue , Infecções por HIV/terapia , Infecções por HIV/virologia , Humanos , Fatores de Tempo , Carga Viral , Replicação Viral/imunologiaRESUMO
Previous research suggests that hamsters 1) fail to retain sodium after mineralocorticoid injections, 2) retain sodium after adrenalectomy equal to controls, and 3) do not develop salt appetite after mineralocorticoid or adrenalectomy. The present studies demonstrate sodium retention, body weight gain, hypernatremia, plasma volume expansion, and reduced fecal sodium excretion after daily injections of deoxycorticosterone acetate (DOCA). Salt appetite appeared after the 3rd and 4th days. Adrenalectomy caused reductions of sodium balance, plasma volume, and food intake, which were reversed by DOCA administration. Mineralocorticoids therefore represent one control of sodium metabolism in hamsters.
Assuntos
Apetite/efeitos dos fármacos , Desoxicorticosterona/farmacologia , Cloreto de Sódio , Sódio/metabolismo , Adrenalectomia , Animais , Cricetinae , Ingestão de Líquidos/efeitos dos fármacos , Fezes/análise , Masculino , Mesocricetus , Volume Plasmático/efeitos dos fármacos , Sódio/sangue , Soluções , Equilíbrio Hidroeletrolítico/efeitos dos fármacosRESUMO
Although CD8+ lymphocytes in human immunodeficiency virus type 1 (HIV-1)-infected individuals have been demonstrated to suppress viral replication, the mechanisms of inhibition have not been defined precisely. A large body of evidence indicates that these cells act via soluble inhibitory factors, but the potential role of HLA class I-restricted cytolysis has remained controversial. Here we demonstrate that HIV-1-specific cytotoxic T lymphocytes (CTL) mediate antiviral suppression by both cytolytic and noncytolytic mechanisms. The predominant mechanism requires direct contact of CTL with the infected cells, is HLA class I restricted, and can achieve complete elimination of detectable virus in infected cell cultures. Inhibition occurs even at high multiplicities of infection or at ratios of CTL to CD4 cells as low as 1:1,000. The other mechanism is mediated by soluble inhibitory factors which are triggered in an antigen-specific and HLA-restricted fashion but then act without HLA restriction. These include MIP-1alpha, MIP-1beta, and RANTES, as well as a distinct factor(s) capable of inhibiting HIV-1 strains insensitive to these chemokines. These data indicate that HIV-1-specific CTL are potent mediators of HIV-1 suppression at cell ratios existing in vivo and demonstrate an antigen-specific trigger for CD8+ cell-derived soluble inhibitory factors. These results suggest that CTL play an important role in the observed antiviral activity of CD8+ cells from infected individuals.
Assuntos
HIV-1/imunologia , Antígenos de Histocompatibilidade Classe I/imunologia , Receptores de Quimiocinas , Linfócitos T Citotóxicos/imunologia , Células Clonais , Citotoxicidade Imunológica , Anticorpos Anti-HIV/biossíntese , Proteína do Núcleo p24 do HIV/imunologia , HIV-1/fisiologia , Antígeno HLA-A2/imunologia , Antígenos HLA-B/imunologia , Antígeno HLA-B14 , Humanos , Receptores CCR5 , Receptores de Citocinas/biossíntese , Células Tumorais Cultivadas , Replicação ViralRESUMO
Increasing evidence suggests that HIV-1-specific cytotoxic T lymphocytes (CTLs) are a key host immune response to HIV-1 infection. Generation of CTL responses for prevention or therapy of HIV-1 infection has several intrinsic technical barriers such as antigen expression and presentation, the varying HLA restrictions between different individuals, and the potential for viral escape by sequence variation or surface molecule alteration on infected cells. A strategy to circumvent these limitations is the construction of a chimeric T cell receptor containing human CD4 or HIV-1-specific Ig sequences linked to the signaling domain of the T cell receptor zeta chain (universal T cell receptor). CD8+ CTLs transduced with this universal receptor can then bind and lyse infected cells that express surface HIV-1 gp120. We evaluated the ability of universal-receptor-bearing CD8+ cells from a seronegative donor to lyse acutely infected cells and inhibit HIV-1 replication in vitro. The kinetics of lysis and efficiency of inhibition were comparable to that of naturally occurring HIV-1-specific CTL clones isolated from infected individuals. Further study will be required to determine the utility of these cells as a therapeutic strategy in vivo.
Assuntos
Antígenos CD4/fisiologia , HIV-1/fisiologia , Proteínas de Membrana/fisiologia , Monócitos/virologia , Receptores de Antígenos de Linfócitos T/fisiologia , Linfócitos T Citotóxicos/imunologia , Linfócitos T Citotóxicos/virologia , Replicação Viral , Síndrome da Imunodeficiência Adquirida/imunologia , Síndrome da Imunodeficiência Adquirida/prevenção & controle , Sequência de Aminoácidos , Antígenos CD4/biossíntese , Linhagem Celular , Células Cultivadas , Epitopos/análise , Epitopos/química , Soronegatividade para HIV/imunologia , HIV-1/patogenicidade , Humanos , Proteínas de Membrana/biossíntese , Monócitos/imunologia , Oligopeptídeos/química , Receptores de Antígenos de Linfócitos T/biossíntese , Proteínas Recombinantes de Fusão/biossíntese , Transfecção , Vírion/fisiologiaRESUMO
The nonconditional RNA packaging mutant SE21Q1b contains cis- and trans-acting defects which cause cellular mRNA, rather than viral genomic RNA, to be nonspecifically packaged into SE21Q1b viral particles. Using genomic libraries of the c-SE21Q1b quail cell line, we have been able to construct a molecular clone of the SE21Q1b provirus. Upon transfection into primary quail embryo fibroblasts, the SE21Q1b molecular clone is able to recapitulate the nonspecific RNA packaging phenotype of the c-SE21Q1b cell line. The RNA packaging phenotypes displayed by several SE21Q1b/avian sarcoma-leukemia virus hybrid provirus constructs have further indicated that sequences responsible for the altered RNA packaging phenotype of SE21Q1b are localized in the left third of the SE21Q1b proviral genome. DNA sequence analysis of this region has revealed that the 5' SE21Q1b deletion has removed 179 bp from the SE21Q1b left long terminal repeat and leader regions. Several differences were detected at the carboxyl terminus of the deduced SE21Q1b nucleocapsid protein sequence in comparison with that of Rous sarcoma virus PR-C. Results of site-directed oligonucleotide mutagenesis experiments indicate, however, that the presence of these residues in the nucleocapsid protein alone is not responsible for the decreased RNA packaging specificity of SE21Q1b.
Assuntos
Vírus Defeituosos/fisiologia , RNA Viral/metabolismo , Retroviridae/fisiologia , Replicação Viral , Sequência de Aminoácidos , Animais , Sequência de Bases , Northern Blotting , Linhagem Celular , Clonagem Molecular , DNA Viral , Vírus Defeituosos/genética , Éxons , Produtos do Gene gag/química , Produtos do Gene gag/genética , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Mutação , Fenótipo , Provírus/genética , Provírus/fisiologia , Mapeamento por Restrição , Retroviridae/genética , Homologia de Sequência do Ácido Nucleico , Transfecção , Replicação Viral/genéticaRESUMO
Numerous studies of human immunodeficiency virus type 1 (HIV-1)-specific cytotoxic T lymphocytes (CTL) have examined their ability to recognize B-cell lines expressing recombinant HIV-1 proteins, but relatively few data regarding the lysis of HIV-1-infected cells by CTL are available. We studied the ability of HIV-1-specific CTL clones of defined epitope specificity and HLA restriction to lyse infected CD4+ cells at serial time points following infection. CD4+ cell lines were acutely infected with HIV-1 IIIB at a high multiplicity of infection, and the kinetics of cell lysis were examined and compared with the kinetics of viral replication. Intracellular HIV-1 p24 expression was detected by 1 to 2 days after infection, reaching over 98% positive cells by day 4. Recognition of the infected cells by HLA A2- and B14-restricted CTL clones closely paralleled intracellular p24 expression and preceded peak virion production. The maximal levels of lysis with Gag-, reverse transcriptase-, and envelope-specific clones were different, however. The Gag- and envelope-specific clones lysed infected cells at levels equivalent to peptide-sensitized controls, whereas lysis by the reverse transcriptase-specific clones plateaued at a lower level. Peptide titration curves indicated that this effect was not due to differences in sensitivity to the cognate epitopes for the different clones. Although HIV-1 infection induced an approximately 50% decrease in class I HLA expression on the surface of infected cells, lysis by CTL clones was unaffected. These studies indicate that HIV-1-specific CTL can efficiently lyse HIV-1-infected CD4+ cells and suggest that the partial downregulation of class I molecules in infected cells does not significantly affect recognition by CTL.
Assuntos
Síndrome da Imunodeficiência Adquirida/imunologia , Citotoxicidade Imunológica , HIV-1/imunologia , Linfócitos T Citotóxicos/imunologia , Sequência de Aminoácidos , Anticorpos , Linfócitos B/imunologia , Linfócitos B/virologia , Linfócitos T CD4-Positivos/imunologia , Linhagem Celular , Células Clonais , Epitopos , Citometria de Fluxo , Produtos do Gene gag/química , Produtos do Gene gag/imunologia , Proteína do Núcleo p24 do HIV/biossíntese , Proteína do Núcleo p24 do HIV/imunologia , HIV-1/fisiologia , Antígeno HLA-A2/imunologia , Antígenos HLA-B/imunologia , Antígeno HLA-B14 , Humanos , Dados de Sequência Molecular , Oligopeptídeos/síntese química , Oligopeptídeos/imunologia , Células Tumorais Cultivadas , Replicação ViralRESUMO
We demonstrate that human immunodeficiency virus type 1 (HIV-1)-specific CD8(+) cytotoxic T lymphocytes (CTL) suppress HIV-1 replication in primary lymphocytes, monocytes, and dendritic cells individually. Viral inhibition is significantly diminished in lymphocyte-dendritic cell clusters, suggesting that these clusters in vivo could be sites where viral replication is more difficult to control by CTL.
Assuntos
Linfócitos T CD4-Positivos/imunologia , Células Dendríticas/imunologia , HIV-1/imunologia , Monócitos/imunologia , Linfócitos T Citotóxicos/imunologia , Linfócitos T CD4-Positivos/virologia , Células Cultivadas , Citotoxicidade Imunológica , Células Dendríticas/virologia , HIV-1/fisiologia , Humanos , Monócitos/virologia , Linfócitos T Citotóxicos/virologia , Replicação ViralRESUMO
CXCR4 is a chemokine receptor used by some strains of HIV-1 as an entry coreceptor in association with cell surface CD4 on human cells. In human immunodeficiency virus type 1 (HIV-1)-infected individuals, the appearance of viral isolates with a tropism for CXCR4 (T tropic) has been correlated with late disease progression. The presumed natural ligands for CXCR4 are SDF-1alpha and SDF-1beta, which are proposed to play a role in blocking T-tropic HIV-1 cell entry. Here, we demonstrate that addition of an N-terminal methionine residue to SDF-1beta (Met-SDF-1beta) results in a dramatically enhanced functional activity compared to that of native SDF-1beta. Equivalent concentrations of Met-SDF-1beta are markedly more inhibitory for T-tropic HIV-1 replication than SDF-1beta. A comparison of the biological activities of these two forms of SDF-1beta reveals that Met-SDF-1beta induces a more pronounced intracellular calcium flux yet binds with slightly lower affinity to CXCR4 than SDF-1beta. Down-modulation of CXCR4 is similar after exposure of cells to either chemokine form for 2 h. However, after a 48-h incubation, the surface expression of CXCR4 is much lower for cells treated with Met-SDF-1beta. The enhanced blocking of T-tropic HIV-1 by Met-SDF-1beta appears to be related to prolonged CXCR4 down-modulation.
Assuntos
Fármacos Anti-HIV/farmacologia , Quimiocinas CXC/farmacologia , HIV-1/efeitos dos fármacos , Metionina/análogos & derivados , Receptores CXCR4/efeitos dos fármacos , Sequência de Aminoácidos , Cálcio/metabolismo , Quimiocina CXCL12 , Quimiocinas CXC/metabolismo , Regulação para Baixo , Humanos , Metionina/farmacologia , Dados de Sequência Molecular , Receptores CXCR4/análiseRESUMO
To address the issue of clonal exhaustion in humans, we monitored HLA class I-restricted, epitope-specific CTL responses in an in utero HIV-1-infected infant from 3 mo through 5 years of age. Serial functional CTL precursor assays demonstrated persistent, vigorous, and broadly directed HIV-1 specific CTL activity with a dominant response against an epitope in HIV-1 Gag-p17 (SLYNTVATL, aa 77-85). A clonal CTL response directed against the immunodominant, HLA-A*0201-restricted epitope was found to persist over the entire observation period, as shown by TCR analysis of cDNA libraries generated from PBMC. The analysis of autologous viral sequences did not reveal any escape mutations within the targeted epitope, and viral load measurement indicated ongoing viral replication. Furthermore, inhibition of viral replication assays indicated that the epitope was properly processed from autologous viral protein. These data demonstrate that persistent exposure to high levels of viral Ag does not necessarily lead to clonal exhaustion and that epitope-specific clonal CTL responses induced within the first weeks of life can persist for years without inducing detectable viral escape variants.
Assuntos
Epitopos de Linfócito T/imunologia , Infecções por HIV/imunologia , HIV-1/imunologia , Complicações Infecciosas na Gravidez/imunologia , Linfócitos T Citotóxicos/imunologia , Linfócitos T Citotóxicos/virologia , Carga Viral , Pré-Escolar , Células Clonais/imunologia , Células Clonais/virologia , Testes Imunológicos de Citotoxicidade , Feminino , Produtos do Gene gag/imunologia , Produtos do Gene gag/isolamento & purificação , Infecções por HIV/transmissão , Infecções por HIV/virologia , HIV-1/fisiologia , Humanos , Lactente , Contagem de Linfócitos , Gravidez , Complicações Infecciosas na Gravidez/virologia , Infecção Puerperal/imunologia , Infecção Puerperal/virologia , Células-Tronco/imunologia , Células-Tronco/virologia , Latência Viral/imunologia , Replicação Viral/imunologiaRESUMO
CD8+ lymphocytes are believed to be important in host defence against the human immunodeficiency virus (HIV)-1, inhibiting HIV-1 replication through both cytolytic and non-cytolytic pathways. The cytolytic pathway involves calcium-dependent exocytosis of perforin and granzyme proteases, as well as Fas-mediated programmed cell death, whereas the noncytolytic pathway involves the release of chemokines that prevent viral entry. Using granzyme A as a marker of cytolytic granule proteins, and macrophage inflammatory protein (MIP)-1alpha and RANTES as markers of HIV-1 inhibitory chemokines, we show that these two very different mediators of viral inhibition are both localized in the cytolytic granules of HIV-1-specific CD8+ cytotoxic T lymphocytes (CTL). Following antigen-specific activation, these mediators are secreted together, facilitating both lysis of virion-producing cells and the inhibition of free virus. In addition, RANTES, MIP-1alpha and MIP-1beta are secreted by CTL as a macromolecular complex containing sulphated proteoglycans. This association appears to have a functional significance, because heparan sulphate facilitates RANTES inhibition of HIV-1 infection of monocytes.
Assuntos
Quimiocina CCL5/metabolismo , Grânulos Citoplasmáticos/metabolismo , HIV-1/imunologia , Proteínas Inflamatórias de Macrófagos/metabolismo , Proteoglicanas/metabolismo , Linfócitos T Citotóxicos/imunologia , Linhagem Celular Transformada , Quimiocina CCL3 , Quimiocina CCL4 , Células Clonais , Citotoxicidade Imunológica , Granzimas , Infecções por HIV/imunologia , HIV-1/fisiologia , Humanos , Ativação Linfocitária , Microscopia Confocal , Serina Endopeptidases/metabolismo , Linfócitos T Citotóxicos/metabolismo , Replicação ViralRESUMO
The precise immunologic functions of CD1d-restricted, CD161+ AV24AJ18 (Valpha24JalphaQ) T cells are not well defined, although production of IL-4 has been suggested as important for priming Th2 responses. However, activation of human Valpha24JalphaQ T cell clones by anti-CD3 resulted in the secretion of multiple cytokines notably important for the recruitment and differentiation of myeloid dendritic cells. Specific activation of Valpha24JalphaQ T cells was CD1d restricted. Expression of CD1d was found on monocyte-derived dendritic cells in vitro, and immunohistochemical staining directly revealed CD1d preferentially expressed on dendritic cells in the paracortical T cell zones of lymph nodes. Moreover, myeloid dendritic cells both activated Valpha24JalphaQ T cells and were susceptible to lysis by these same regulatory T cells. Because myeloid dendritic cells are a major source of IL-12 and control Th1 cell differentiation, their elimination by lysis is a mechanism for limiting the generation of Th1 cells and thus regulating Th1/Th2 responses.