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ABSTRACT: Background
Surfactant protein D (SP-D) is an essential component of the innate immune defense against pathogens within the airways. SP-D also regulates allergic inflammation and promotes the removal of apoptotic cells. SP-D dysregulation is evident in several pulmonary diseases. Our aim was to investigate whether airway and serum levels of SP-D are altered in treatment-resistant severe asthma.Methods
SP-D concentrations were measured in matched serum and BAL samples collected from 10 healthy control subjects (HC) and 50 patients with asthma (22 with mild asthma [MA] and 28 with severe asthma [SA]). These samples were also evaluated by using Western blot analysis to investigate variations in SP-D size.Results
SP-D levels in BAL samples were significantly lower in SA compared with HC and MA (P < .001) and inversely correlated with BAL eosinophil cationic protein concentrations in SA (P < .01). Serum SP-D was significantly increased in SA compared with HC and MA (P < .001), and BAL/serum ratios were significantly lower in SA compared with HC and MA (P < .001). Reduced SP-D levels in BAL samples, with concomitant increases in serum in SA, were associated with degraded fragments of SP-D in the serum and increased BAL neutrophil counts and lipopolysaccharide levels.Conclusions
These findings suggest defective innate immunity within the airways in SA, as reflected by low BAL SP-D concentrations and altered bacterial presence with airway neutrophilia. Furthermore, BAL SP-D leakage into the serum in patients with SA may provide a peripheral blood biomarker, reflecting increased epithelial damage and/or epithelial permeability within the peripheral airways.
SUBMITTER: Mackay RM
PROVIDER: S-EPMC4944769 | biostudies-literature | 2016 May
REPOSITORIES: biostudies-literature
Mackay Rose-Marie A RM Grainge Christopher L CL Lau Laurie C LC Barber Clair C Clark Howard W HW Howarth Peter H PH
Chest 20160113 5
<h4>Background</h4>Surfactant protein D (SP-D) is an essential component of the innate immune defense against pathogens within the airways. SP-D also regulates allergic inflammation and promotes the removal of apoptotic cells. SP-D dysregulation is evident in several pulmonary diseases. Our aim was to investigate whether airway and serum levels of SP-D are altered in treatment-resistant severe asthma.<h4>Methods</h4>SP-D concentrations were measured in matched serum and BAL samples collected fro ...[more]