RESUMO
BACKGROUNDRespiratory syncytial virus (RSV) is an important cause of acute pulmonary disease and one of the last remaining major infections of childhood for which there is no vaccine. CD4+ T cells play a key role in antiviral immunity, but they have been little studied in the human lung.METHODSHealthy adult volunteers were inoculated i.n. with RSV A Memphis 37. CD4+ T cells in blood and the lower airway were analyzed by flow cytometry and immunohistochemistry. Bronchial soluble mediators were measured using quantitative PCR and MesoScale Discovery. Epitope mapping was performed by IFN-γ ELISpot screening, confirmed by in vitro MHC binding.RESULTSActivated CD4+ T cell frequencies in bronchoalveolar lavage correlated strongly with local C-X-C motif chemokine 10 levels. Thirty-nine epitopes were identified, predominantly toward the 3' end of the viral genome. Five novel MHC II tetramers were made using an immunodominant EFYQSTCSAVSKGYL (F-EFY) epitope restricted to HLA-DR4, -DR9, and -DR11 (combined allelic frequency: 15% in Europeans) and G-DDF restricted to HLA-DPA1*01:03/DPB1*02:01 and -DPA1*01:03/DPB1*04:01 (allelic frequency: 55%). Tetramer labeling revealed enrichment of resident memory CD4+ T (Trm) cells in the lower airway; these Trm cells displayed progressive differentiation, downregulation of costimulatory molecules, and elevated CXCR3 expression as infection evolved.CONCLUSIONSHuman infection challenge provides a unique opportunity to study the breadth of specificity and dynamics of RSV-specific T-cell responses in the target organ, allowing the precise investigation of Trm recognizing novel viral antigens over time. The new tools that we describe enable precise tracking of RSV-specific CD4+ cells, potentially accelerating the development of effective vaccines.TRIAL REGISTRATIONClinicalTrials.gov NCT02755948.FUNDINGMedical Research Council, Wellcome Trust, National Institute for Health Research.
Assuntos
Linfócitos T CD4-Positivos/imunologia , Mapeamento de Epitopos , Infecções por Vírus Respiratório Sincicial/imunologia , Vírus Sinciciais Respiratórios/imunologia , Adolescente , Adulto , Linfócitos T CD4-Positivos/patologia , Epitopos de Linfócito T , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Infecções por Vírus Respiratório Sincicial/patologiaRESUMO
In animal models, resident memory CD8+ T (Trm) cells assist in respiratory virus elimination but their importance in man has not been determined. Here, using experimental human respiratory syncytial virus (RSV) infection, we investigate systemic and local virus-specific CD8+ T-cell responses in adult volunteers. Having defined the immunodominance hierarchy, we analyse phenotype and function longitudinally in blood and by serial bronchoscopy. Despite rapid clinical recovery, we note surprisingly extensive lower airway inflammation with persistent viral antigen and cellular infiltrates. Pulmonary virus-specific CD8+ T cells display a CD69+CD103+ Trm phenotype and accumulate to strikingly high frequencies into convalescence without continued proliferation. While these have a more highly differentiated phenotype, they express fewer cytotoxicity markers than in blood. Nevertheless, their abundance before infection correlates with reduced symptoms and viral load, implying that CD8+ Trm cells in the human lung can confer protection against severe respiratory viral disease when humoral immunity is overcome.
Assuntos
Linfócitos T CD8-Positivos/citologia , Linfócitos T CD8-Positivos/imunologia , Memória Imunológica , Infecções por Vírus Respiratório Sincicial/imunologia , Adolescente , Adulto , Animais , Diferenciação Celular , Feminino , Humanos , Pulmão/citologia , Pulmão/imunologia , Pulmão/virologia , Masculino , Camundongos , Pessoa de Meia-Idade , Infecções por Vírus Respiratório Sincicial/fisiopatologia , Infecções por Vírus Respiratório Sincicial/virologia , Vírus Sinciciais Respiratórios/genética , Vírus Sinciciais Respiratórios/imunologia , Vírus Sinciciais Respiratórios/fisiologia , Adulto JovemAssuntos
Corticosteroides/uso terapêutico , Antiasmáticos/uso terapêutico , Asma/tratamento farmacológico , Infecções por Picornaviridae/tratamento farmacológico , Adulto , Asma/complicações , Asma/imunologia , Asma/patologia , Citocinas/biossíntese , Gerenciamento Clínico , Feminino , Volume Expiratório Forçado , Humanos , Imunoglobulina E/biossíntese , Masculino , Pessoa de Meia-Idade , Infecções por Picornaviridae/complicações , Infecções por Picornaviridae/imunologia , Infecções por Picornaviridae/patologia , Rhinovirus/imunologia , Índice de Gravidade de Doença , Equilíbrio Th1-Th2/efeitos dos fármacosRESUMO
Rhinoviruses cause the common cold and exacerbations of asthma. Animal models of infection have identified a protective role for interleukin-18 (IL-18). Following experimental rhinovirus infection, we observed increased respiratory symptoms in healthy and asthmatic subjects with low nasal and bronchial IL-18 levels.