Segmental allergen challenge alters multimeric structure and function of surfactant protein D in humans.
BACKGROUND
Surfactant protein D (SP-D), a 43-kD collectin, is synthesized and secreted by airway epithelia as a dodecamer formed by assembly of four trimeric subunits. We have previously shown that the quaternary structure of SP-D can be altered during inflammatory lung injury through its modification by S-nitrosylation, which in turn alters its functional behavior producing a proinflammatory response in effector cells.


OBJECTIVE
We hypothesized that alterations in structure and function of SP-D may occur in humans with acute allergic inflammation.


METHODS
Bronchoalveolar lavage (BAL) fluid was collected from 15 nonsmoking patients with mild intermittent allergic asthma before and 24 hours after segmental provocation with saline, allergen, LPS, and mixtures of allergen and LPS. Structural modifications of SP-D were analyzed by native and sodium dodecyl sulfate gel electrophoresis.


RESULTS
The multimeric structure of native SP-D was found to be disrupted after provocation with allergen or a mixture of allergen and LPS. Interestingly, under reducing conditions, sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated that 7 of 15 patients with asthma developed an abnormal cross-linked SP-D band after segmental challenge with either allergen or a mixture of allergen with LPS but not LPS alone. Importantly, patients with asthma with cross-linked SP-D demonstrated significantly higher levels of BAL eosinophils, nitrogen oxides, IL-4, IL-5, IL-13, and S-nitrosothiol-SP-D compared with patients without cross-linked SP-D.


CONCLUSIONS
We conclude that segmental allergen challenge results in changes of SP-D multimeric structure and that these modifications are associated with an altered local inflammatory response in the distal airways.
Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia,PA, USA.
Elena N
EN
Atochina-Vasserman
Carla
C
Winkler
Helen
H
Abramova
Frank
F
Schaumann
Norbert
N
Krug
Andrew J
AJ
Gow
Michael F
MF
Beers
Jens M
JM
Hohlfeld
D000328:Adult; D000485:Allergens / Q000276:immunology*; D000704:Analysis of Variance; D001249:Asthma / Q000276:immunology*; D001985:Bronchial Provocation Tests; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry / Q000166:cytology; D002633:Chemotaxis / Q000276:immunology; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006801:Humans; D015151:Immunoblotting; D008297:Male; D037663:Pulmonary Surfactant-Associated Protein D / Q000737:chemistry* / Q000276:immunology*; D012016:Reference Values; D012130:Respiratory Hypersensitivity / Q000276:immunology*; D026403:S-Nitrosothiols / Q000737:chemistry / Q000378:metabolism; D012494:Sampling Studies; D012720:Severity of Illness Index; D055815:Young Adult
D000485:Allergens; D037663:Pulmonary Surfactant-Associated Protein D; D026403:S-Nitrosothiols