The Immune System in the Lung
Asthma Studies:
The Immune system is always engaged in surveilling the lung. This involves ongoing ‘sampling’ of the airway contents, as we reveal, by a subset of phagocytic cells called dendritic cells. These cells compete with another set of cells, called alveolar macrophages, which also can ingest materials that are breathed in. In Allergic Airway diseases (of which Asthma is an example), direct imaging reveals a bottleneck that forms adjacent to the airway; a meeting site is formed where inhaled particle appears to be ‘presented’ to instigating T cells. This site will be a focus for our ongoing work, in an effort to understand how immunity and tolerance are achieved at this mucosal surface.
What is the background tissue architecture that the immune system must protect?
Render of a tiled image of an entire mouse lung. Tissue was stained with Avidin the binds predominantly to airway epithelium. Movie explores the 3D topology of this organ and peels away imaging plane to reveal individual cells comprising alveoli and vasculature. (Credit: Erin Oswald).
Real time bright field imaging of a large airway in a lung section two hours after sectioning shows ciliary movement on the surface of a large airway.
Movie plays at the speed that it was acquired (i.e. real-time). From Thornton et al. 2012.
The surveillance of the lung by lung dendritic cells.
Lung section of CD11c-EYFP (green) Actin-CFP (blue) shows DC localization just below the surface of the airway and between alveoli. Timelapse shows center-of-mass motility of DCs along the surface of the airway with little center-of-mass motility of alveolar DCs. Note that timelapse repeats 2 times. Timestamp indicates elapsed time. From Thornton et al. 2012.
Ongoing surveillance of the surfactant/airspace in the atria of alveoli.
Zoom-in and timelapse of an OVA allergen challenged CD11c-EYFP (green) lung stained with Hoechst (blue) shows alveolar DCs sending processes along the alveolar epithelium. Note that timelapse repeats 3 times after the zoom. Timestamp indicates elapsed time. From Thornton et al. 2012.
Dendritic cells in alveoli actively ingest inhaled particulates.
Zoom-in and timelapse of an OVA allergen challenged c-fms-EGFP (green) Actin-CFP (blue) lung after inhalation of red polystyrene beads (red) shows direct uptake of a bead by an alveolar DC. Note that timelapse repeats 3 times after the zoom. Timestamp indicates elapsed time. From Thornton et al. 2012.
Dendritic cells move to and accumulate near the airways in asthma where they interact with T cells.
Zoom-in and timelapse of an OVA allergen challenged CD11c-EYFP (green) Actin-CFP (blue) that received CD2-RFP OTII T cells (red) before sensitization shows sustained T-DC interactions near an airway. Note that timelapse repeats 3 times after the zoom. Timestamp indicates elapsed time. From Thornton et al. 2012.
Understanding the origins and nature of lung injury:
Exposure of the lungs to overinflation, as might happen in ventilator-induced lung injury, or to lipid products from bacteria are associated with clinical lung-injury.
Dynamics of Fluid Leakage into Lung in response to bacterial products.
Two-photon video of lung tissue marked with actin-CFP (blue) showing dextran leak (red) into the extravascular space 50 min post-LPS treatment (5 mg/kg, i.t., 40 mm z stack). From Looney et al. Nature Methods 2011.
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