RESUMEN
Allergic asthma develops in the mucosal tissue of small bronchi. At these sites, local cytokine production by Th2/Th17 cells is believed to be critical for the development of tissue eosinophilia/neutrophilia. Using the mouse trachea as a relevant model of human small airways, we performed advanced in vivo dynamic and in situ static imaging to visualize individual cytokine-producing T cells in the airway mucosa and to define their immediate cellular environment. Upon allergen sensitization, newly recruited CD4+ T cells formed discrete Ag-driven clusters with dendritic cells (DCs). Within T cell-DC clusters, a small fraction of CD4+ T cells produced IL-13 or IL-17 following prolonged Ag-specific interactions with DCs. As a result of local Th2 cytokine signaling, eosinophils were recruited into these clusters. Neutrophils also infiltrated these clusters in a T cell-dependent manner, but their mucosal distribution was more diffuse. Our findings reveal the focal nature of allergen-driven responses in the airways and define multiple steps with potential for interference with the progression of asthmatic pathology.
Asunto(s)
Asma/inmunología , Linfocitos T CD4-Positivos/inmunología , Quimiotaxis de Leucocito/inmunología , Citocinas/biosíntesis , Células Dendríticas/inmunología , Traslado Adoptivo , Animales , Asma/metabolismo , Linfocitos T CD4-Positivos/metabolismo , Citocinas/inmunología , Modelos Animales de Enfermedad , Femenino , Citometría de Flujo , Hipersensibilidad/inmunología , Inmunidad Mucosa/inmunología , Inmunohistoquímica , Masculino , Ratones , Microscopía Confocal , Mucosa Respiratoria/inmunologíaRESUMEN
The mucosal layer of conducting airways is the primary tissue exposed to inhaled microorganisms, allergens and pollutants. We developed an in vivo two-photon microscopic approach that allows performing dynamic imaging studies in the mouse trachea, which is a commonly used in vivo model of human small-diameter bronchi. By providing stabilized access to the tracheal mucosa without intubation, our setup uniquely allows dynamic in vivo imaging of mucociliary clearance and steady-state immune cell behavior within the complex airway mucosal tissue.