Increased surfactant protein a and d expression in acute ovalbumin-induced allergic airway inflammation in brown norway rats.
BACKGROUND
The surfactant proteins SP-A and SP-D, components of the innate immune system, are involved in host defence.


OBJECTIVE
We tested the hypothesis that ovalbumin (OVA) challenge leads to an upregulation of both proteins in alveolar epithelial type II cells (AEII) and Clara cells and to an enhanced uptake by macrophages.


METHODS
After sensitization with OVA and heat-killed Bordetella pertussis challenge followed intratracheally with 0.5% OVA on day 13. One day after challenge lung tissue and bronchoalveolar lavage fluid (BALF) of sensitized NaCl- and OVA-challenged Brown Norway rats were compared with home cage controls using qRt-PCR, Western blot and immunohistochemistry.


RESULTS
After OVA challenge (1) eosinophils increased significantly in the BALF, (2) the total amount of SP-A and SP-D was significantly increased in lung tissue, (3) the amount of SP-A was significantly and the amount of SP-D was remarkably elevated in BALF, and (4) the levels of SP-A and SP-D mRNA in lung tissue were significantly elevated. Using quantitative immunohistochemistry, we found (5) significantly higher surface fractions of SP-A- and SP-D-labelled AEII, (6) no differences in the surface fractions of SP-A- and SP-D-labelled bronchial Clara cells, and (7) a significantly increased cell density of unlabelled and SP-A-labelled macrophages.


CONCLUSIONS
Thus, combining molecular biological and histological methods we suggest that after OVA challenge (1) AEII but not Clara cells show a significantly higher expression of SP-A and SP-D leading also to higher amounts of both SPs in BALF and (2) macrophages gather predominantly SP-A.
Schmiedl
A
A
Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover, Germany. Schmiedl.Andreas@Mh-hannover.de
Lührmann
A
A
Pabst
R
R
Koslowski
R
R
D000485:Allergens / Q000009:adverse effects / Q000276:immunology; D000818:Animals; D016535:Bronchial Hyperreactivity / Q000276:immunology; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry / Q000276:immunology; D004804:Eosinophils / Q000166:cytology / Q000276:immunology; D007249:Inflammation / Q000139:chemically induced / Q000276:immunology / Q000378:metabolism; D008168:Lung / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D008297:Male; D010047:Ovalbumin / Q000276:immunology*; D011650:Pulmonary Alveoli / Q000166:cytology / Q000378:metabolism*; D037662:Pulmonary Surfactant-Associated Protein A / Q000235:genetics / Q000378:metabolism*; D037663:Pulmonary Surfactant-Associated Protein D / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D011914:Rats, Inbred BN; D012130:Respiratory Hypersensitivity / Q000139:chemically induced / Q000276:immunology* / Q000378:metabolism; D015854:Up-Regulation
D000485:Allergens; D037662:Pulmonary Surfactant-Associated Protein A; D037663:Pulmonary Surfactant-Associated Protein D; D010047:Ovalbumin