RESUMO
Daclizumab is a humanized monoclonal antibody that prevents interleukin-2 (IL-2) binding to CD25, blocking IL-2 signaling by cells that require high-affinity IL-2 receptors to mediate IL-2 signaling. The phase 2a CHOICE study evaluating daclizumab as a treatment for multiple sclerosis (MS) included longitudinal analysis of activated T cell counts. Whereas an exposure-dependent relationship was observed between daclizumab and reductions in HLA-DR(+)-activated T cells, a similar relationship was not observed for reductions in CD25 levels. The objective of this report is to determine the mechanism by which daclizumab reduces CD25 levels on peripheral blood mononuclear cells (PBMCs) using cytometric techniques. Daclizumab reduced T cell CD25 levels through a mechanism that required the daclizumab-Fc domain interaction with Fc receptors (FcR) on monocytes, but not on natural killer (NK) cells, and was unrelated to internalization or cell killing. Activated CD4(+) T cells and FoxP3(+) Treg cells showed evidence of trogocytosis of the CD25 antigen in the presence of monocytes. A daclizumab variant that retained affinity for CD25 but lacked FcR binding did not induce trogocytosis and was significantly less potent as an inhibitor of IL-2-induced proliferation of PBMCs. In conclusion, Daclizumab-induced monocyte-mediated trogocytosis of CD25 from T cells appears to be an additional mechanism contributing to daclizumab inhibition of IL-2 signaling.
Assuntos
Anticorpos Monoclonais Humanizados/uso terapêutico , Imunoglobulina G/uso terapêutico , Imunossupressores/uso terapêutico , Subunidade alfa de Receptor de Interleucina-2/efeitos dos fármacos , Monócitos/imunologia , Esclerose Múltipla/tratamento farmacológico , Subpopulações de Linfócitos T/efeitos dos fármacos , Daclizumabe , Método Duplo-Cego , Citometria de Fluxo , Humanos , Subunidade alfa de Receptor de Interleucina-2/biossíntese , Ativação Linfocitária/efeitos dos fármacos , Esclerose Múltipla/imunologia , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo , Linfócitos T/efeitos dos fármacos , Linfócitos T/imunologia , Linfócitos T/metabolismoRESUMO
Myelin-specific T lymphocytes are considered essential in the pathogenesis of multiple sclerosis. The myelin basic protein peptide (a.a. 83-99) represents one candidate antigen; therefore, it was chosen to design an altered peptide ligand, CGP77116, for specific immunotherapy of multiple sclerosis. A magnetic resonance imaging-controlled phase II clinical trial with this altered peptide ligand documented that it was poorly tolerated at the dose tested, and the trial had therefore to be halted. Improvement or worsening of clinical or magnetic resonance imaging parameters could not be demonstrated in this small group of individuals because of the short treatment duration. Three patients developed exacerbations of multiple sclerosis, and in two this could be linked to altered peptide ligand treatment by immunological studies demonstrating the encephalitogenic potential of the myelin basic protein peptide (a.a. 83-99) in a subgroup of patients. These data raise important considerations for the use of specific immunotherapies in general.
Assuntos
Esclerose Múltipla/tratamento farmacológico , Esclerose Múltipla/imunologia , Proteína Básica da Mielina/uso terapêutico , Fragmentos de Peptídeos/uso terapêutico , Peptídeos/uso terapêutico , Adolescente , Adulto , Sequência de Aminoácidos , Estudos de Casos e Controles , Reações Cruzadas , Citocinas/metabolismo , Relação Dose-Resposta a Droga , Humanos , Ligantes , Imageamento por Ressonância Magnética , Pessoa de Meia-Idade , Dados de Sequência Molecular , Proteína Básica da Mielina/imunologia , Proteína Básica da Mielina/metabolismo , Fragmentos de Peptídeos/imunologia , Fragmentos de Peptídeos/metabolismo , Peptídeos/efeitos adversos , Linfócitos T/efeitos dos fármacos , Linfócitos T/imunologia , Falha de TratamentoRESUMO
Elucidating the cellular immune response to infectious agents is a prerequisite for understanding disease pathogenesis and designing effective vaccines. In the identification of microbial T-cell epitopes, the availability of purified or recombinant bacterial proteins has been a chief limiting factor. In chronic infectious diseases such as Lyme disease, immune-mediated damage may add to the effects of direct infection by means of molecular mimicry to tissue autoantigens. Here, we describe a new method to effectively identify both microbial epitopes and candidate autoantigens. The approach combines data acquisition by positional scanning peptide combinatorial libraries and biometric data analysis by generation of scoring matrices. In a patient with chronic neuroborreliosis, we show that this strategy leads to the identification of potentially relevant T-cell targets derived from both Borrelia burgdorferi and the host. We also found that the antigen specificity of a single T-cell clone can be degenerate and yet the clone can preferentially recognize different peptides derived from the same organism, thus demonstrating that flexibility in T-cell recognition does not preclude specificity. This approach has potential applications in the identification of ligands in infectious diseases, tumors and autoimmune diseases.
Assuntos
Epitopos/isolamento & purificação , Doença de Lyme/imunologia , Mimetismo Molecular/imunologia , Linfócitos T/imunologia , Adulto , Sequência de Aminoácidos , Antígenos de Bactérias/genética , Antígenos de Bactérias/isolamento & purificação , Autoantígenos/genética , Autoantígenos/isolamento & purificação , Proteínas de Bactérias/genética , Proteínas de Bactérias/imunologia , Proteínas de Bactérias/isolamento & purificação , Grupo Borrelia Burgdorferi/genética , Grupo Borrelia Burgdorferi/imunologia , Células Clonais , Epitopos/genética , Humanos , Imunidade Celular , Técnicas In Vitro , Doença de Lyme/genética , Neuroborreliose de Lyme/genética , Neuroborreliose de Lyme/imunologia , Ativação Linfocitária , Masculino , Mimetismo Molecular/genética , Polimorfismo Conformacional de Fita SimplesRESUMO
An important subgroup of human cellular receptors uses peptides as signaling molecules. Modifications of these signaling peptides, usually by amino acid substitutions in crucial receptor contact sites (i.e., altered peptide ligands, APLs), is an approach for highly selective and specific modulation of the receptor function. One of the major applications of APLs is immunology, where APLs have been examined for therapeutic modulation of T cell function, both for diseases characterized by unwanted activation of T cells (e.g., autoimmune diseases) and for disorders with suboptimal T cell activation (e.g., immunotherapy of cancers and infectious disorders). APLs also occur in vivo, for example, as escape mutants of infectious agents, and play an important role in thymic positive selection. We summarize current knowledge of the basic mechanisms of the effects of APLs with special focus on T cell receptor signaling and the use of APLs for the treatment of autoimmune diseases.
Assuntos
Antígenos/imunologia , Imunoterapia/métodos , Peptídeos/imunologia , Sequência de Aminoácidos , Substituição de Aminoácidos , Células Apresentadoras de Antígenos/imunologia , Doenças Autoimunes/imunologia , Doenças Autoimunes/terapia , Humanos , Ligantes , Linfócitos/imunologia , Complexo Principal de Histocompatibilidade/imunologia , Dados de Sequência Molecular , Peptídeos/genética , Receptores de Antígenos de Linfócitos T/imunologiaRESUMO
OBJECTIVE: To assess the relationship between CD56(bright) natural killer (NK) cells and multiple sclerosis (MS) disease activity in patients with relapsing-remitting MS treated with daclizumab high-yield process (DAC HYP). METHODS: Data were from patients enrolled in a 52-week randomized, double-blind, placebo-controlled study of DAC HYP and its extension study. Assessments included relationships of CD56(bright) NK cell numbers (identified using fluorescence-activated cell sorting) at weeks 4 and 8 with the numbers of new or newly enlarging T2-hyperintense lesions between weeks 24 and 52 and the annualized relapse rate. RESULTS: In DAC HYP-treated patients but not placebo-treated patients, the numbers of CD56(bright) NK cells increased over 52 weeks of treatment, and their numbers at weeks 4 and 8 predicted the number of new or newly enlarging T2-hyperintense lesions between weeks 24 and 52 of treatment (p ≤ 0.005 for each comparison). Similar but nonsignificant trends were observed between CD56(bright) NK cell counts and the annualized relapse rate in DAC HYP-treated patients. DAC HYP-treated patients who showed lower levels of expansion of CD56(bright) NK cells still developed fewer new or newly enlarging T2-hyperintense lesions than placebo-treated patients during the first year of treatment. CONCLUSIONS: CD56(bright) NK cells appear to mediate some of the treatment-related effects of DAC HYP, but their numbers do not account for the full effect of DAC HYP on MS-related outcomes.
RESUMO
OBJECTIVE: To define the mechanism of action of glatiramer acetate (GA; formerly known as copolymer-1) as an immunomodulatory treatment for MS. BACKGROUND: The proposed mechanisms of action of GA include 1) functional inhibition of myelin-reactive T cells by human leukocyte antigen (HLA) blocking, 2) T-cell receptor (TCR) antagonism, and 3) induction of T helper 2 (Th2) immunomodulatory cells. In this report, the authors examined the effects of GA on the functional activation of human T-cell clones (TCC) specific for myelin basic protein (MBP) and for foreign antigens. Several questions were addressed: Is the inhibitory effect of GA specific for autoantigens? Is it mediated by blocking the interaction between peptide and HLA molecule? Is GA a partial agonist or TCR antagonist, or does it induce anergy? Does it induce Th2 modulatory T cells? METHODS: The effects of GA on antigen-induced activation of human TCC specific for MBP, influenza virus hemagglutinin, and Borrelia burgdorferi were studied by proliferation and cytokine measurements, TCR downmodulation, and anergy assays. GA-specific TCC were generated in vitro from the peripheral blood of patients and healthy controls by limiting dilution. RESULTS: GA more strongly inhibited the proliferation of MBP, as compared with foreign antigen-specific TCC; in some MBP-specific TCC, the production of Th1-type cytokines was preferentially inhibited. In addition to HLA competition, the induction of anergy, but not direct TCR antagonism, was observed. Numerous GA-specific TCC were generated from the peripheral blood of both MS patients and normal controls, and a fraction of these showed a Th2 phenotype. CONCLUSIONS: This study confirms a preferential inhibitory effect of GA on autoreactive TCC. With respect to cellular mechanisms, although HLA competition appears to play the most important role in functional inhibition in vitro, a direct effect on the TCR may be involved at least in some autoreactive T cells as shown by anergy induction. Although not confirmed at the clonal level, it is demonstrated further that GA induces T cells that crossreact with myelin proteins. GA-specific, Th2-modulatory cells may play an important role in mediating the effect of the drug in vivo.
Assuntos
Adjuvantes Imunológicos/metabolismo , Esclerose Múltipla/imunologia , Peptídeos/imunologia , Citometria de Fluxo , Acetato de Glatiramer , Humanos , Complexo Principal de Histocompatibilidade/imunologia , Esclerose Múltipla/sangue , Peptídeos/sangue , Linfócitos T/imunologiaRESUMO
Effects on adhesion molecules of immune cells might contribute to the mode of action of interferon-beta (IFN-beta) in multiple sclerosis (MS). We have serially monitored the cell surface expression of integrins CD49d (VLA-4) and CD11a (LFA-1) on fresh T lymphocyte subpopulations from 5 MS patients monthly for 2 months prior to treatment and for 3 months on treatment with IFN-beta1b. In parallel, we assessed inflammatory disease activity by monthly contrast-enhanced magnetic resonance imaging (MRI). IFN-beta treatment specifically downregulated CD49d expression on CD8+ and CD4+/CD45RO+ 'memory' T lymphocytes and differentially modulated the proportion of CD4+, CD8+ and CD27+ T cells. These effects may play an important role in the reduction of central nervous system cell trafficking and inflammation in MS.
Assuntos
Adjuvantes Imunológicos/administração & dosagem , Antígenos CD/metabolismo , Integrinas/metabolismo , Interferon beta/administração & dosagem , Esclerose Múltipla Recidivante-Remitente/tratamento farmacológico , Esclerose Múltipla Recidivante-Remitente/imunologia , Receptores de Retorno de Linfócitos/metabolismo , Linfócitos T/imunologia , Antígenos CD/imunologia , Biomarcadores , Antígenos CD4/análise , Antígenos CD58/análise , Antígenos CD8/análise , Regulação para Baixo/imunologia , Feminino , Citometria de Fluxo , Antígenos HLA-DR/análise , Humanos , Memória Imunológica/efeitos dos fármacos , Memória Imunológica/imunologia , Integrina alfa4 , Integrina alfa4beta1 , Integrina beta1/análise , Integrinas/imunologia , Molécula 1 de Adesão Intercelular/análise , Antígenos Comuns de Leucócito/análise , Antígeno-1 Associado à Função Linfocitária/análise , Imageamento por Ressonância Magnética , Masculino , Esclerose Múltipla Recidivante-Remitente/diagnóstico , Receptores de Retorno de Linfócitos/imunologia , Linfócitos T/química , Linfócitos T/metabolismo , Membro 7 da Superfamília de Receptores de Fatores de Necrose Tumoral/análiseRESUMO
We have developed a new technique that allows us to quantify antigen-specific T cells, and to determine their functional phenotype and origin from naive versus memory populations. Using this methodology, we have characterized a total of 286 T-cell lines specific for myelin basic protein (MBP) and influenza hemagglutinin from 16 multiple sclerosis (MS) patients and nine healthy donors. Our data support the notion that MBP-specific T cells undergo in vivo activation in MS patients and indicate a presence of immune dysregulation that renders MS patients prone to develop autoimmunity. Our methodology offers a way to study antigen-specific T-cell characteristics as a surrogate marker in immunotherapy trials.
Assuntos
Autoantígenos/imunologia , Autoimunidade/imunologia , Memória Imunológica , Imunofenotipagem/métodos , Interleucina-7/farmacologia , Linfócitos T/imunologia , Adulto , Especificidade de Anticorpos , Biomarcadores , Linfócitos T CD4-Positivos/imunologia , Estudos de Casos e Controles , Divisão Celular , Citometria de Fluxo , Humanos , Interferon gama/biossíntese , Interleucina-4/biossíntese , Cinética , Antígenos Comuns de Leucócito/biossíntese , Leucócitos Mononucleares/imunologia , Esclerose Múltipla/imunologia , Proteína Básica da Mielina/imunologia , Fatores de TempoRESUMO
Vesnarinone (OPC-8212) is a synthetic quinolinone derivative with inotropic and immunomodulatory effects. Vesnarinone has been shown to inhibit tumor necrosis factor-alpha (TNF alpha) produced by mitogen stimulated macrophages, and to inhibit phosphodiesterase (PDE) type III in cardiac muscle. TNF alpha and interferon-gamma (IFNgamma) have been implicated in the pathogenesis of autoimmune diseases, and both cytokines are targets for therapeutic intervention. IFNgamma can enhance autoimmune disease through direct effects, and indirectly by priming macrophages to produce TNF alpha. In this study, we demonstrate that while vesnarinone enhances basal TNF alpha levels, it inhibits TNF alpha production in peripheral blood mononuclear cells from multiple sclerosis (MS) patients and healthy donors stimulated with lipopolysaccharide (LPS) or primed with IFNgamma and stimulated with suboptimal doses of LPS. In addition, vesnarinone inhibited TNF alpha production in primary adult human microglial cultures. However, in contrast to rolipram, another TNF alpha inhibiting agent, vesnarinone failed to inhibit TNF alpha production by myelin basic protein specific T-cell lines. As oral TNF inhibitors are currently being considered in the USA for clinical application in MS, the implications of our findings on the development of vesnarinone for treatment of MS are discussed.
Assuntos
Adjuvantes Imunológicos/farmacologia , Microglia/metabolismo , Esclerose Múltipla/tratamento farmacológico , Quinolinas/farmacologia , Linfócitos T/metabolismo , Fator de Necrose Tumoral alfa/biossíntese , Anti-Inflamatórios não Esteroides/farmacologia , Antígenos Virais/imunologia , Divisão Celular/efeitos dos fármacos , Divisão Celular/imunologia , Linhagem Celular , Relação Dose-Resposta a Droga , Ensaio de Imunoadsorção Enzimática , Humanos , Influenza Humana/imunologia , Interferon gama/biossíntese , Lipopolissacarídeos/farmacologia , Microglia/citologia , Microglia/efeitos dos fármacos , Esclerose Múltipla/imunologia , Esclerose Múltipla/metabolismo , Pirazinas , Pirrolidinonas/farmacologia , Rolipram , Linfócitos T/citologia , Linfócitos T/virologiaRESUMO
Multiple Sclerosis (MS) is considered a T cell-mediated autoimmune disease of central nervous system myelin. Based on elegant experiments in an animal model of MS, experimental allergic encephalomyelitis (EAE), a number of myelin proteins and peptides derived from these can induce inflammatory demyelinating lesions. Recent studies with transgenic mice expressing human HLA-DR molecules and a myelin basic protein (MBP)-specific T cell receptor as well as data from a phase II clinical trial with an altered peptide ligand based on MBP peptide (83-99) provide convincing evidence that the pathogenetic concepts which largely stem from the above EAE studies are valid in MS, too.
Assuntos
Autoantígenos/imunologia , Esclerose Múltipla/imunologia , Receptores de Antígenos de Linfócitos T/imunologia , Linfócitos T/imunologia , Animais , Ensaios Clínicos Fase II como Assunto , Humanos , Ligantes , Esclerose Múltipla/fisiopatologia , Proteína Básica da Mielina/imunologia , Bainha de Mielina/imunologia , Fragmentos de Peptídeos/imunologia , Fragmentos de Peptídeos/farmacologiaRESUMO
OBJECTIVES: We previously reported that daclizumab, a humanized monoclonal antibody against CD25, reduced contrast-enhancing lesions (CEL) in patients with multiple sclerosis (MS) who were suboptimal responders to interferon-ß and that this response correlated with expansion of CD56(bright) NK cells. These data have been reproduced in a placebo-controlled multicenter trial (CHOICE study). The current study investigates whether daclizumab monotherapy reduces CEL in untreated patients with relapsing-remitting MS (RRMS) and the effects of daclizumab on the intrathecal immune system. METHODS: Sixteen patients with RRMS with high inflammatory activity were enrolled in an open-label, baseline-vs-treatment, phase II trial of daclizumab monotherapy for 54 weeks and followed by serial clinical and MRI examinations and immunologic biomarkers measured in the whole blood and CSF. RESULTS: The trial achieved predefined outcomes. There was an 87.7% reduction in brain CEL (primary) and improvements in Multiple Sclerosis Functional Composite (secondary), Scripps Neurologic Rating Scale, and Expanded Disability Status Scale (tertiary) outcomes. There was significant expansion of CD56(bright) NK cells in peripheral blood and CSF, with resultant decrease in T cells/NK cells and B cells/NK cells ratios and IL-12p40 in the CSF. Surprisingly, CD25 Tac epitope was equally blocked on the immune cells in the CSF and in peripheral blood. CONCLUSIONS: Daclizumab monotherapy inhibits formation of MS plaques in patients with RRMS and immunoregulatory NK cells may suppress activation of pathogenic immune responses directly in the CNS compartment. CLASSIFICATION OF EVIDENCE: The study provides Class III evidence that daclizumab reduces the number of contrast-enhancing lesions in treatment-naive patients with RRMS over a 54-week period.
Assuntos
Anticorpos Monoclonais Humanizados/administração & dosagem , Imunoglobulina G/administração & dosagem , Imunossupressores/administração & dosagem , Esclerose Múltipla/tratamento farmacológico , Adolescente , Adulto , Idoso , Antígenos CD/metabolismo , Citocinas/sangue , Citocinas/líquido cefalorraquidiano , Daclizumabe , Avaliação da Deficiência , Ensaio de Imunoadsorção Enzimática/métodos , Feminino , Citometria de Fluxo , Seguimentos , Humanos , Injeções Espinhais/métodos , Linfócitos/metabolismo , Linfócitos/patologia , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Esclerose Múltipla/sangue , Esclerose Múltipla/líquido cefalorraquidiano , Esclerose Múltipla/patologia , Exame Neurológico , Adulto JovemRESUMO
BACKGROUND: Whereas recent data from imaging studies challenge the prevailing notion that multiple sclerosis (MS) is purely an inflammatory disease, pathologic studies suggest differences in the disease processes between individual patients with MS. The ability to dissect the pathophysiologic disease heterogeneity, if it indeed exists, by methodologies that can be applied in vivo is important both for the development of new therapeutics and for the ability to identify the optimal therapy for an individual patient. OBJECTIVE: To design a stratification algorithm for patients with MS based on accepted MRI measurements reflective of inflammation and axonal damage/tissue loss and to assess if such MS subgroups retain their intergroup differences long term. METHODS: Mathematical modeling was used to select three discriminatory MRI measures for clinical outcome based on the cross-sectional analysis of 71 patients with untreated MS and tested general applicability of the stratification scheme on the independent longitudinal cohort of 71 MS patients. RESULTS: By consecutive employment of MRI measures reflective of inflammation and tissue loss, the authors were able to separate MS patients into four clinically meaningful subgroups. The analysis of the longitudinal confirmatory cohort demonstrated persistence of the intergroup differences in selected MRI measures for 8 years. CONCLUSIONS: The inflammatory activity and destructiveness of the multiple sclerosis process are to some degree independent of each other, and the successive evaluation of both of these variables can strengthen prediction of clinical outcome in individual patients.
Assuntos
Algoritmos , Imageamento por Ressonância Magnética/métodos , Esclerose Múltipla/classificação , Esclerose Múltipla/diagnóstico , Degeneração Walleriana/diagnóstico , Adulto , Axônios/patologia , Biomarcadores , Sistema Nervoso Central/patologia , Sistema Nervoso Central/fisiopatologia , Estudos de Coortes , Estudos Transversais , Diagnóstico Diferencial , Progressão da Doença , Feminino , Humanos , Inflamação/diagnóstico , Inflamação/fisiopatologia , Estudos Longitudinais , Imageamento por Ressonância Magnética/normas , Masculino , Pessoa de Meia-Idade , Modelos Teóricos , Esclerose Múltipla/fisiopatologia , Valor Preditivo dos Testes , Prognóstico , Degeneração Walleriana/fisiopatologiaRESUMO
Myelin-associated oligodendrocytic basic protein (MOBP) is an abundant myelin constituent expressed exclusively by oligodendrocytes, the myelin-forming cells of the CNS. We report that MOBP causes experimental allergic encephalomyelitis and is associated with multiple sclerosis. First, we note that purified recombinant MOBP inoculated into SJL/J mice produces CNS disease. Tests of overlapping peptides spanning the murine MOBP molecule map the encephalitogenic site to amino acids 37-60. MOBP-induced experimental allergic encephalomyelitis shows a severe clinical course and is characterized by a prominent CD4+ T lymphocyte infiltration and a lesser presence of CD8+ T cells and microglia/macrophages around vessels and in the white matter of the CNS. Second, PBL obtained from patients with relapsing/remitting multiple sclerosis mount a proliferative response to human MOBP, especially at amino acids 21-39. This response equals or exceeds the response to myelin basic protein and an influenza virus hemagglutinin peptide, both serving as internal controls. Thus, a novel myelin Ag, MOBP aa 37-60, plays a role in rodent autoimmune CNS disease, and its human MOBP counterpart is associated with the human demyelinating disease multiple sclerosis.
Assuntos
Encefalomielite Autoimune Experimental/imunologia , Epitopos de Linfócito T/isolamento & purificação , Esclerose Múltipla/imunologia , Glicoproteína Associada a Mielina/química , Glicoproteína Associada a Mielina/imunologia , Sequência de Aminoácidos , Animais , Encefalomielite Autoimune Experimental/etiologia , Encefalomielite Autoimune Experimental/metabolismo , Encefalomielite Autoimune Experimental/patologia , Humanos , Ativação Linfocitária/imunologia , Camundongos , Camundongos Endogâmicos , Dados de Sequência Molecular , Esclerose Múltipla/metabolismo , Esclerose Múltipla/patologia , Proteínas da Mielina , Glicoproteína Associada a Mielina/genética , Glicoproteína Associada a Mielina/fisiologia , Glicoproteína Mielina-Oligodendrócito , Fragmentos de Peptídeos/imunologia , Ratos , Proteínas Recombinantes de Fusão/imunologia , Linfócitos T/imunologia , Linfócitos T/patologiaRESUMO
Phosphodiesterase-4 (PDE4) inhibitors have the potential to modulate immune responses from the Th1 toward the Th2 phenotype and are considered candidate therapies for Th1-mediated autoimmune disorders. However, depending on the model and cell types employed, studies of atopic individuals have come to the opposite conclusion, i.e., that PDE inhibitors may be beneficial in asthma. Using in vitro immunopharmacologic techniques we analyzed the effects of PDE4 and PDE3 inhibitors on human immune cells to address these discrepancies and broaden our understanding of their mechanism of action. Our results indicate that PDE inhibitors have complex inhibitory effects within in vivo achievable concentration ranges on Th1-mediated immunity, whereas Th2-mediated responses are mostly unaffected or enhanced. The Th2 skewing of the developing immune response is explained by the effects of PDE inhibitors on several factors contributing to T cell priming: the cytokine milieu; the type of costimulatory signal, i.e., up-regulation of CD86 and down-regulation of CD80; and the Ag avidity. The combination of PDE4 and PDE3 inhibitors expresses synergistic effects and may broaden the therapeutic window. Finally, we observed a differential sensitivity to PDE inhibition in autoreactive vs foreign Ag-specific T cells and cells derived from multiple sclerosis patients vs those derived from healthy donors. This suggests that PDE inhibition weakens the strength of the T cell stimulus and corrects the underlying disease-associated cytokine skew in T cell-mediated autoimmune disorders. These new findings broaden the understanding of the immunomodulatory actions of PDE inhibitors and underscore their promising drug profile for the treatment of autoimmune disorders.
Assuntos
3',5'-AMP Cíclico Fosfodiesterases/antagonistas & inibidores , Esclerose Múltipla/enzimologia , Esclerose Múltipla/terapia , Inibidores de Fosfodiesterase/uso terapêutico , Células Th1/enzimologia , Células Th1/imunologia , Adjuvantes Imunológicos/farmacologia , Adjuvantes Imunológicos/uso terapêutico , Sequência de Aminoácidos , Autoantígenos/imunologia , Antígeno B7-1/biossíntese , Linhagem Celular , Nucleotídeo Cíclico Fosfodiesterase do Tipo 3 , Nucleotídeo Cíclico Fosfodiesterase do Tipo 4 , Citocinas/biossíntese , Relação Dose-Resposta Imunológica , Epitopos de Linfócito T/imunologia , Glicoproteínas de Hemaglutininação de Vírus da Influenza/imunologia , Humanos , Ativação Linfocitária/efeitos dos fármacos , Dados de Sequência Molecular , Esclerose Múltipla/imunologia , Proteína Básica da Mielina/imunologia , Inibidores de Fosfodiesterase/farmacologia , Rolipram/farmacologia , Subpopulações de Linfócitos T/efeitos dos fármacos , Subpopulações de Linfócitos T/enzimologia , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo , Células Th1/efeitos dos fármacosRESUMO
Given our current knowledge, there is a need for the early institution of immunomodulatory therapy, especially for patients with poor prognostic factors (motor and cerebellar symptoms, frequent disease exacerbations, and a high level of activity on magnetic resonance imaging ). Patients who progress despite immunomodulatory therapy should be reevaluated in terms of diagnosis, development of neutralizing antibodies, or compliance. If a patient has a partial response to immunomodulatory therapy but his or her disease, as assessed by clinical and MRI criteria, remains very active, every effort should be made to modify disease progression by searching for an immunosuppressive therapy regimen before irreversible and considerable disability has accumulated. For the majority of patients, multiple sclerosis (MS) is a chronic condition. Therefore, until a curative treatment has been developed, the available repertoire of immunosuppressive or immunomodulatory treatments should be assessed with respect to the possibility of long-term use. This is particularly important for new immunosuppressive drugs, such as cladribine or mitoxantrone, or for invasive procedures, such as total lymphoid irradiation or autologous bone marrow transplantation. For the latter treatments, experience with long-term administration is not available or the potential side effects (eg, cardiotoxicity with mitoxantrone) limit the cumulative dose. These considerations may limit long-term administration and thus the general usefulness of some drugs. Even with proven efficacy, we need to define the next step once treatment has to be discontinued. We should also address whether exacerbating disease by discontinuing an effective therapy is a potential hazard. What other therapeutic options remain once the current treatment is discontinued? Answers are not readily available at the moment, but the question should influence our decisions in the selection of traditional, well-studied or new, potentially promising therapies.
RESUMO
T cells with specificity for self-Ags are normally present in the peripheral blood, and, upon activation, may target tissue Ags and become involved in the pathogenesis of autoimmune processes. In multiple sclerosis, a demyelinating disease of the CNS, it is postulated that inflammatory damage is initiated by CD4+ T cells reactive to myelin Ags. To investigate the potential naive vs memory origin of circulating myelin-reactive cells, we have generated myelin basic protein (MBP)- and tetanus toxoid-specific T cell clones from CD45RA+/RO- and CD45RO+/RA- CD4+ T cell subsets from the peripheral blood of multiple sclerosis patients and controls. Our results show that 1) the response to MBP, different from that to TT, predominantly emerges from the CD45RA+ subset; 2) the reactivity to immunodominant MBP epitopes mostly resides in the CD45RA+ subset; 3) in each individual, the recognition of single MBP epitopes is skewed to either subset, with no overlap in the Ag fine specificity; and 4) in spite of a lower expression of costimulatory and adhesion molecules, CD45RA+ subset-derived clones recognize epitopes with higher functional Ag avidity. These findings point to a central role of the naive CD45RA+ T cell subset as the source for immunodominant, potentially pathogenic effector CD4+ T cell responses in humans.
Assuntos
Autoantígenos/imunologia , Linfócitos T CD4-Positivos/imunologia , Epitopos de Linfócito T/metabolismo , Memória Imunológica , Antígenos Comuns de Leucócito/biossíntese , Subpopulações de Linfócitos T/imunologia , Adulto , Autoantígenos/metabolismo , Linfócitos T CD4-Positivos/citologia , Linfócitos T CD4-Positivos/metabolismo , Moléculas de Adesão Celular/biossíntese , Separação Celular , Células Clonais , Citocinas/metabolismo , Feminino , Humanos , Epitopos Imunodominantes/metabolismo , Interfase/imunologia , Selectina L/biossíntese , Antígenos Comuns de Leucócito/metabolismo , Ativação Linfocitária , Masculino , Pessoa de Meia-Idade , Proteína Básica da Mielina/imunologia , Proteína Básica da Mielina/metabolismo , Ligação Proteica/imunologia , Subpopulações de Linfócitos T/citologia , Subpopulações de Linfócitos T/metabolismo , Membro 7 da Superfamília de Receptores de Fatores de Necrose Tumoral/biossínteseRESUMO
An open-label study was performed to assess the effectiveness of oral azathioprine (AZA) on augmenting the response to interferon beta-1b (IFNbeta-1b) in patients with treatment-refractory relapsing-remitting MS. Six IFNbeta-1b-treated MS patients with continued disease activity were studied on IFNbeta-1b and AZA therapy for a median period of 15 months. A 69% reduction in the number of contrast-enhancing lesions was observed during the combination therapy (p = 0.002).
Assuntos
Azatioprina/uso terapêutico , Interferon beta/uso terapêutico , Esclerose Múltipla Recidivante-Remitente/tratamento farmacológico , Adolescente , Adulto , Quimioterapia Combinada , Feminino , Humanos , Interferon beta-1b , Estudos Longitudinais , Imageamento por Ressonância Magnética , Masculino , Esclerose Múltipla Recidivante-Remitente/diagnóstico , Falha de Tratamento , Resultado do TratamentoRESUMO
Multiple sclerosis (MS) is considered an autoimmune disease that is mediated by proinflammatory T helper-1 lymphocytes. The putative mechanism of interferon-beta (IFN-beta), an approved treatment for MS, includes the inhibition of T-cell proliferation, blocking of blood-brain-barrier opening and T-cell transmigration into the brain via interference with cell adhesion, and the upregulation of anti-inflammatory cytokines. In the present study, a gene expression analysis of IFN-beta-treated peripheral blood mononuclear cells by cDNA microarray documents the broad effects of IFN-beta that are not purely anti-inflammatory. Specifically, we addressed the effect of IFN-beta on T helper-1 differentiation- or lineage markers such as the IL-12 receptor beta2 chain and the chemokine receptor CCR5 that have been implicated in the pathogenesis of MS. Both markers were significantly upregulated in vitro and in vivo under IFN-beta therapy, supporting that this cytokine exerts complex effects on the immune system. The combination of cDNA microarray and quantitative PCR will expand our knowledge of the immunological effects of such pleiotropic agents as IFN-beta, may provide a key to why certain patients fail to respond, and eventually may influence our view of the disease pathogenesis.
Assuntos
Adjuvantes Imunológicos/farmacologia , Interferon beta/farmacologia , Esclerose Múltipla Recidivante-Remitente/sangue , Células Th1/metabolismo , Regulação para Cima/genética , Regulação para Cima/imunologia , Adjuvantes Imunológicos/uso terapêutico , Biomarcadores/sangue , Diferenciação Celular/genética , Diferenciação Celular/imunologia , Células Cultivadas , Humanos , Interferon beta/uso terapêutico , Leucócitos Mononucleares/imunologia , Leucócitos Mononucleares/metabolismo , Esclerose Múltipla Recidivante-Remitente/tratamento farmacológico , Análise de Sequência com Séries de Oligonucleotídeos/métodos , RNA Mensageiro/biossíntese , Receptores CCR5/biossíntese , Receptores CCR5/genética , Receptores de Interleucina/biossíntese , Receptores de Interleucina/genética , Receptores de Interleucina-12 , Células Th1/citologia , Células Th1/imunologiaRESUMO
The concept of molecular mimicry provides and elegant framework as to how cross-reactivity between antigens from a foreign agent with self proteins may trigger autoimmune diseases. While it was previously thought that sequence and structural homology between foreign and self proteins or the sharing of T cell receptor (TCR) and MHC-binding motifs are required for molecular mimicry to occur, we have shown that even completely unrelated peptide sequences may lead to cross-recognition by T cells. The use of synthetic combinatorial peptide libraries in the positional scanning format (PS-SCL) together with novel biometric prediction approaches has allowed us to describe the recognition profiles of individual autoreactive T cell clones (TCC) with unprecedented accuracy. Through studies of myelin-specific TCC as well as clones from the nervous system of patients suffering from chronic central nervous (CNS) Lyme disease it has become clear that at least some T cells are more degenerate than previously anticipated. These data will not only help us to redefine what constitutes specific T cell recognition, but also allow us to study in more detail the biological role of molecular mimicry. A recent clinical trial with an altered peptide ligand (APL) of one of the candidate myelin basic protein (MBP) epitopes in MS (amino acids 83-99) has shown that such a modified MBP peptide may not only have therapeutic efficacy, but also bears the potential to exacerbate disease. Thus, we provide firm evidence that the basic principles of cross-recognition and their pathogenetic significance are relevant in MS.