Allergen particle binding by human primary bronchial epithelial cells is modulated by surfactant protein D.
BACKGROUND
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. Our previous work demonstrated that SP-D increases the uptake of SPP by alveolar macrophages. In the present study, we investigated the uptake of SPP in human primary epithelial cells and the potential modulation by SP-D. The patho-physiological consequence was evaluated by measurement of pro-inflammatory mediators.


METHODS
SPP were isolated from timothy grass and subsequently fluorescently labelled. Human primary bronchial epithelial cells were incubated with SPP or polystyrene particles (PP) in the presence and absence of surfactant protein D. In addition, different sizes and surface charges of the PP were studied. Particle uptake was evaluated by flow cytometry and confocal microscopy. Soluble mediators were measured by enzyme linked immunosorbent assay or bead array.


RESULTS
SPP were taken up by primary epithelial cells in a dose dependent manner. This uptake was coincided with secretion of Interleukin (IL)-8. SP-D increased the fraction of bronchial epithelial cells that bound SPP but not the fraction of cells that internalized SPP. SPP-induced secretion of IL-8 was further increased by SP-D. PP were bound and internalized by epithelial cells but this was not modulated by SP-D.


CONCLUSIONS
Epithelial cells bind and internalize SPP and PP which leads to increased IL-8 secretion. SP-D promotes attachment of SPP to epithelial cells and may thus be involved in the inflammatory response to inhaled allergen.
Schleh
Carsten
C
Fraunhofer Institute for Toxicology and Experimental Medicine, Hannover, Germany.
Erpenbeck
Veit J
VJ
Winkler
Carla
C
Lauenstein
Hans D
HD
Nassimi
Matthias
M
Braun
Armin
A
Krug
Norbert
N
Hohlfeld
Jens M
JM
D000818:Animals; D052179:Antigens, Plant / Q000378:metabolism*; D001692:Biological Transport; D001980:Bronchi / Q000276:immunology / Q000378:metabolism*; D045744:Cell Line, Tumor; D004797:Enzyme-Linked Immunosorbent Assay; D004847:Epithelial Cells / Q000276:immunology / Q000378:metabolism*; D005434:Flow Cytometry; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism; D018613:Microscopy, Confocal; D010316:Particle Size; D031784:Phleum / Q000276:immunology*; D010940:Plant Proteins / Q000276:immunology / Q000378:metabolism*; D011058:Pollen / Q000276:immunology / Q000378:metabolism*; D037663:Pulmonary Surfactant-Associated Protein D / Q000378:metabolism*; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D013499:Surface Properties; D013997:Time Factors
D052179:Antigens, Plant; C508606:CXCL8 protein, human; D018836:Inflammation Mediators; D016209:Interleukin-8; D010940:Plant Proteins; D037663:Pulmonary Surfactant-Associated Protein D; D011994:Recombinant Proteins