Surfactant Protein D modulates allergen particle uptake and inflammatory response in a human epithelial airway model
1 Fraunhofer Institute of Toxicology and Experimental Medicine, Nikolai-Fuch-Str. 1, 30635 Hannover, Germany
2 MedicalSchoolHannover, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
3 Respiratory Medicine, Berne University Hospital, Murtenstrasse 50, Postfach 44, 3010 Bern, Switzerland
4 Adolphe Merkle Institute, University of Fribourg, Rte de l'Ancienne Papeterie CP 209, 1723 Marly 1, Switzerland
5 Technical University Carolo-Wilhelmina Braunschweig, 38092 Braunschweig Germany
Respiratory Research 2012, 13:8 doi:10.1186/1465-9921-13-8Published: 1 February 2012
Allergen-containing subpollen particles (SPP) are released from whole plant pollen upon contact with water or even high humidity. Because of their size SPP can preferentially reach the lower airways where they come into contact with surfactant protein (SP)-D. The aim of the present study was to investigate the influence of SP-D in a complex three-dimensional human epithelial airway model, which simulates the most important barrier functions of the epithelial airway. The uptake of SPP as well as the secretion of pro-inflammatory cytokines was investigated.
SPP were isolated from timothy grass and subsequently fluorescently labeled. A human epithelial airway model was built by using human Type II-pneumocyte like cells (A549 cells), human monocyte derived macrophages as well as human monocyte derived dendritic cells. The epithelial cell model was incubated with SPP in the presence and absence of surfactant protein D. Particle uptake was evaluated by confocal microscopy and advanced computer-controlled analysis. Finally, human primary CD4+ T-Cells were added to the epithelial airway model and soluble mediators were measured by enzyme linked immunosorbent assay or bead array.
SPP were taken up by epithelial cells, macrophages, and dendritic cells. This uptake coincided with secretion of pro-inflammatory cytokines and chemokines. SP-D modulated the uptake of SPP in a cell type specific way (e.g. increased number of macrophages and epithelial cells, which participated in allergen particle uptake) and led to a decreased secretion of pro-inflammatory cytokines.
These results display a possible mechanism of how SP-D can modulate the inflammatory response to inhaled allergen.