Browsing by Subject "Pulmonary Surfactant-Associated Protein A"

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    Obese asthmatic patients have decreased surfactant protein A levels: Mechanisms and implications.
    (The Journal of allergy and clinical immunology, 2018-03) Lugogo, Njira; Francisco, Dave; Addison, Kenneth J; Manne, Akarsh; Pederson, William; Ingram, Jennifer L; Green, Cynthia L; Suratt, Benjamin T; Lee, James J; Sunday, Mary E; Kraft, Monica; Ledford, Julie G

    Background

    Eosinophils are prominent in some patients with asthma and are increased in the submucosa in a subgroup of obese patients with asthma (OAs). Surfactant protein A (SP-A) modulates host responses to infectious and environmental insults.

    Objective

    We sought to determine whether SP-A levels are altered in OAs compared with a control group and to determine the implications of these alterations in SP-A levels in asthmatic patients.

    Methods

    Bronchoalveolar lavage fluid from 23 lean, 12 overweight, and 20 obese subjects were examined for SP-A. Mouse tracheal epithelial cells grown at an air-liquid interface were used for mechanistic studies. SP-A-/- mice were challenged in allergen models, and exogenous SP-A therapy was given after the last challenge. Eosinophils were visualized and quantitated in lung parenchyma by means of immunostaining.

    Results

    Significantly less SP-A (P = .002) was detected in samples from OAs compared with those from control subjects. A univariable regression model found SP-A levels were significantly negatively correlated with body mass index (r = -0.33, P = .014), whereas multivariable modeling demonstrated that the correlation depended both on asthma status (P = .017) and the interaction of asthma and body mass index (P = .008). Addition of exogenous TNF-α to mouse tracheal epithelial cells was sufficient to attenuate SP-A and eotaxin secretion. Allergen-challenged SP-A-/- mice that received SP-A therapy had significantly less tissue eosinophilia compared with mice receiving vehicle.

    Conclusions

    SP-A functions as an important mediator in resolving tissue and lavage fluid eosinophilia in allergic mouse models. Decreased levels of SP-A in OAs, which could be due to increased local TNF-α levels, might lead to impaired eosinophil resolution and could contribute to the eosinophilic asthma phenotype.
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    ItemOpen Access
    Surfactant protein A is defective in abrogating inflammation in asthma.
    (American journal of physiology. Lung cellular and molecular physiology, 2011-10) Wang, Ying; Voelker, Dennis R; Lugogo, Njira L; Wang, Guirong; Floros, Joanna; Ingram, Jennifer L; Chu, Hong Wei; Church, Tony D; Kandasamy, Pitchaimani; Fertel, Daniel; Wright, Jo Rae; Kraft, Monica
    Surfactant protein A (SP-A) regulates a variety of immune cell functions. We determined the ability of SP-A derived from normal and asthmatic subjects to modulate the inflammatory response elicited by Mycoplasma pneumoniae, a pathogen known to exacerbate asthma. Fourteen asthmatic and 10 normal control subjects underwent bronchoscopy with airway brushing and bronchoalveolar lavage (BAL). Total SP-A was extracted from BAL. The ratio of SP-A1 to total SP-A (SP-A1/SP-A) and the binding of total SP-A to M. pneumoniae membranes were determined. Airway epithelial cells from subjects were exposed to either normal or asthmatic SP-A before exposure to M. pneumoniae. IL-8 protein and MUC5AC mRNA were measured. Total BAL SP-A concentration did not differ between groups, but the percentage SP-A1 was significantly increased in BAL of asthmatic compared with normal subjects. SP-A1/SP-A significantly correlated with maximum binding of total SP-A to M. pneumoniae, but only in asthma. SP-A derived from asthmatic subjects did not significantly attenuate IL-8 and MUC5AC in the setting of M. pneumoniae infection compared with SP-A derived from normal subjects. We conclude that SP-A derived from asthmatic subjects does not abrogate inflammation effectively, and this dysfunction may be modulated by SP-A1/SP-A.