The role of surfactant in asthma

Pulmonary surfactant is a unique mixture of lipids and surfactant-specific proteins that covers the entire alveolar surface of the lungs. Surfactant is not restricted to the alveolar compartment; it also reaches terminal conducting airways and is present in upper airway secretions. While the role of surfactant in the alveolar compartment has been intensively elucidated both in health and disease states, the possible role of surfactant in the airways requires further research. This review summarizes the current knowledge on surfactant functions regarding the airway compartment and highlights the impact of various surfactant components on allergic inflammation in asthma

Independent Information of Nonspecific Biomarkers in Exhaled Breath Condensate

Background: Exhaled breath condensate (EBC) has been used for diagnosing and monitoring respiratory disorders. For clinical purposes the assessment of easy-to-obtain nonspecific markers seems particularly interesting. Objectives: As these measures are related to each other, our objective was to extract the independent information in global EBC markers across a range of respiratory disorders. Methods: EBC was collected from patients with asthma (n = 18), chronic obstructive pulmonary disease (n = 17), and cystic fibrosis (n = 46), as well as from lung transplant (LTX) recipients (n = 14) and healthy controls (n = 26). Samples were assessed for electrical conductivity, ammonia, pH, and nitrite/nitrate. pH was measured after both deaeration with argon and CO(2) standardization. Additionally, the fraction of exhaled nitric oxide (FE(NO)) was assessed. Factor analysis was applied to identify major factors concerning these measures. Results: Three independent factors were detected; the first comprised conductivity, ammonia, and pH, especially when standardized using CO(2), the second nitrite/nitrate, and the third FE(NO). Conductivity and ammonia were highly correlated (r = 0.968; p < 0.001). FE(NO) provided independent information mainly in asthma. The nonspecific EBC markers showed considerable overlap between patient groups and healthy subjects. However, conductivity, ammonia, pH standardized for CO(2) and nitrite/nitrate were increased in LTX recipients compared to healthy controls (p < 0.05 each). Conclusions: A panel of nonspecific easy-to-obtain exhaled breath markers could be reduced to 3 independent factors. The information content of conductivity, ammonia, and pH after CO(2) equilibration appeared to be similar, while FE(NO) was independent. The increased levels of these biomarkers in LTX might indicate a potential for their use in these patients. Copyright (C) 2010 S. Karger AG, Base

Measurement of exhaled volatile organic compounds from patients with chronic obstructive pulmonary disease (COPD) using closed gas loop GC-IMS and GC-APCI-MS

Due to its high sensitivity, compact size and low cost Ion Mobility Spectrometry (IMS) has the potential to become a point-of-care breath analyzer. Therefore, we developed a prototype of a compact, closed gas loop IMS with gas chromatographic (GC) pre-separation and high resolving power of R = 90. In this study, we evaluated the performance of this GC-IMS under clinical conditions in a COPD study to find correlations between VOCs (10 ppbv to 1 ppmv) and COPD. Furthermore, in order to investigate possible correlations between ultra-low concentrated breath VOCs (0.1 pptv to 1 ppbv) and COPD, a modified mass spectrometer (MS) with atmospheric pressure chemical ionization (APCI) and GC pre-separation (GC-APCI-MS) was used. The GC-IMS has been used in 58 subjects (21 smokers with moderate COPD, 12 ex-smokers with COPD, 16 healthy smokers and 9 non-smokers). GC-APCI-MS data were available for 94 subjects (21 smokers with moderate COPD, 25 ex-smokers with COPD, 25 healthy smokers and 23 non-smokers). For 44 subjects, a comparison between GC-IMS and GC-APCI-MS data could be performed. Due to service intervals, subject availability and corrupt data, patient numbers were different for GC-APCI-MS and GC-IMS measurements. Using GC-IMS, three VOCs have been found showing a significant difference between healthy controls and patients with COPD. In the GC-APCI-MS data, we only observed one distinctive VOC, which has been identified as 2-pentanone. This proof-of-principle study shows the potential of our high-resolution GC-IMS in the clinical environment. Due to different linear dynamic response ranges, the data of GC-IMS and GC-APCI-MS were only comparable to a limited extent

Effect of Acute Ozone Induced Airway Inflammation on Human Sympathetic Nerve Traffic: A Randomized, Placebo Controlled, Crossover Study

Background: Ozone concentrations in ambient air are related to cardiopulmonary perturbations in the aging population. Increased central sympathetic nerve activity induced by local airway inflammation may be one possible mechanism. Methodology/Principal Findings: To elucidate this issue further, we performed a randomized, double-blind, cross-over study, including 14 healthy subjects (3 females, age 22-47 years), who underwent a 3 h exposure with intermittent exercise to either ozone (250 ppb) or clean air. Induced sputum was collected 3 h after exposure. Nineteen to 22 hours after exposure, we recorded ECG, finger blood pressure, brachial blood pressure, respiration, cardiac output, and muscle sympathetic nerve activity (MSNA) at rest, during deep breathing, maximum-inspiratory breath hold, and a Valsalva maneuver. While the ozone exposure induced the expected airway inflammation, as indicated by a significant increase in sputum neutrophils, we did not detect a significant estimated treatment effect adjusted for period on cardiovascular measurements. Resting heart rate (clean air: 59 +/- 62, ozone 60 +/- 62 bpm), blood pressure (clean air: 121 +/- 3/71 +/- 2 mmHg; ozone: 121 +/- 2/71 +/- 2mmHg), cardiac output (clean air: 7.42 +/- 0.29 mmHg; ozone: 7.98 +/- 0.60 l/min), and plasma norepinephrine levels (clean air: 213 +/- 21 pg/ml; ozone: 202 +/- 16 pg/ml), were similar on both study days. No difference of resting MSNA was observed between ozone and air exposure (air: 2362, ozone: 2362 bursts/min). Maximum MSNA obtained at the end of apnea (air: 44 +/- 4, ozone: 48 +/- 4 bursts/min) and during the phase II of the Valsalva maneuver (air: 64 +/- 5, ozone: 57 +/- 6 bursts/min) was similar. Conclusions/Significance: Our study suggests that acute ozone-induced airway inflammation does not increase resting sympathetic nerve traffic in healthy subjects, an observation that is relevant for environmental health. However, we can not exclude that chronic airway inflammation may contribute to sympathetic activation

The preclinical and phase 1 development of the novel oral cathepsin C inhibitor BI 1291583

Preclinical and phase 1 study results indicate that BI 1291583 is a reversible, highly potent and highly selective CatC inhibitor that markedly inhibits active NSP production in a dose-dependent manner, supporting phase 2 trials in bronchiectasis patients https://bit.ly/47PZ8E5.</p

The preclinical and phase 1 development of the novel oral cathepsin C inhibitor BI 1291583

Preclinical and phase 1 study results indicate that BI 1291583 is a reversible, highly potent and highly selective CatC inhibitor that markedly inhibits active NSP production in a dose-dependent manner, supporting phase 2 trials in bronchiectasis patients https://bit.ly/47PZ8E5.</p

Surfactant function in lung transplantation after 24 hours of ischemia: Advantage of retrograde flush perfusion for preservation

AbstractObjective: Surfactant function was shown to be impaired in clinical and experimental lung transplantation. This study was designed to define the impact of retrograde flush perfusion on graft and surfactant function after an extended period of ischemia. Methods: Left lung transplantation was performed after 24 hours of graft ischemia in 12 pigs. In half of the grafts antegrade cold flush perfusion (Perfadex) was used for preservation. In the second group grafts were flushed in a retrograde fashion via the left atrium. Graft function was monitored for 7 hours after transplantation. Before transplantation (basal) and after 2 hours of reperfusion, bronchoalveolar lavage fluid was obtained. Minimal surface tension of bronchoalveolar lavage fluid was determined and the ratio of small and large surfactant aggregates was calculated. Lung water content was analyzed online in the reperfusion period. Results: Right-sided heart failure developed in 2 animals of group 1 (antegrade perfusion) within 2 and 4.5 hours of reperfusion, respectively. All other pigs survived the observation period. PO2/FIO2 (P =.001) and dynamic lung compliance (P =.001) were superior in retrogradely flushed grafts. A comparable increase of minimal surface tension was found after reperfusion in both groups. Small/large surfactant aggregate ratio after reperfusion (P =.03), as well as extravascular lung water content, was higher in the antegrade perfusion group. Conclusion: Retrograde flush perfusion for 24-hour lung preservation with low-potassium dextran (Perfadex) solution led to better initial graft function than the standard antegrade perfusion technique. A moderate impairment of surfactant function was found in both groups, which was more pronounced in the antegrade perfusion group

Impact of endobronchial allergen provocation on macrophage phenotype in asthmatics

Background: The role of M2 polarized macrophages (MF) during the allergic airway inflammation has been discussed in various animal models. However, their presence and relevance during the chronic and acute phase of allergic airway inflammation in humans has not been fully elucidated so far. In the present study we phenotypically characterized macrophages with regard to M2 polarization in mice, a human in vitro and a human ex vivo model with primary lung cells after endobronchial provocation. Results: Macrophages remained polarized beyond clearance of the acute allergic airway inflammation in mice. Alveolar macrophages of asthmatics revealed increased mRNA expression of CCL13, CCL17 and CLEC10A in response to allergen challenge as well as increased surface expression of CD86. Further, mRNA expression of CCL13, CCL17, and CLEC10A was increased in asthmatics at baseline compared to healthy subjects. The mRNA expression of CCL17 and CLEC10A correlated significantly with the degree of eosinophilia (each P < .01). Furthermore, macrophages from asthmatics released significant amounts of CCL17 protein in vitro which was also found increased in BAL fluid after allergen provocation. Conclusions: This study supports previous findings of M2 macrophage polarization in asthmatic subjects during the acute course of the allergic inflammation and provides evidence for their contribution to the Th2 inflammation

Invasive versus noninvasive measurement of allergic and cholinergic airway responsiveness in mice

BACKGROUND: This study seeks to compare the ability of repeatable invasive and noninvasive lung function methods to assess allergen-specific and cholinergic airway responsiveness (AR) in intact, spontaneously breathing BALB/c mice. METHODS: Using noninvasive head-out body plethysmography and the decrease in tidal midexpiratory flow (EF(50)), we determined early AR (EAR) to inhaled Aspergillus fumigatus antigens in conscious mice. These measurements were paralleled by invasive determination of pulmonary conductance (GL), dynamic compliance (Cdyn) and EF(50 )in another group of anesthetized, orotracheally intubated mice. RESULTS: With both methods, allergic mice, sensitized and boosted with A. fumigatus, elicited allergen-specific EAR to A. fumigatus (p < 0.05 versus controls). Dose-response studies to aerosolized methacholine (MCh) were performed in the same animals 48 h later, showing that allergic mice relative to controls were distinctly more responsive (p < 0.05) and revealed acute airway inflammation as evidenced from increased eosinophils and lymphocytes in bronchoalveolar lavage. CONCLUSION: We conclude that invasive and noninvasive pulmonary function tests are capable of detecting both allergen-specific and cholinergic AR in intact, allergic mice. The invasive determination of GL and Cdyn is superior in sensitivity, whereas the noninvasive EF(50 )method is particularly appropriate for quick and repeatable screening of respiratory function in large numbers of conscious mice

Surfactant Protein D modulates allergen particle uptake and inflammatory response in a human epithelial airway model

<p>Abstract</p> <p>Background</p> <p>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. The aim of the present study was to investigate the influence of SP-D in a complex three-dimensional human epithelial airway model, which simulates the most important barrier functions of the epithelial airway. The uptake of SPP as well as the secretion of pro-inflammatory cytokines was investigated.</p> <p>Methods</p> <p>SPP were isolated from timothy grass and subsequently fluorescently labeled. A human epithelial airway model was built by using human Type II-pneumocyte like cells (A549 cells), human monocyte derived macrophages as well as human monocyte derived dendritic cells. The epithelial cell model was incubated with SPP in the presence and absence of surfactant protein D. Particle uptake was evaluated by confocal microscopy and advanced computer-controlled analysis. Finally, human primary CD4⁺T-Cells were added to the epithelial airway model and soluble mediators were measured by enzyme linked immunosorbent assay or bead array.</p> <p>Results</p> <p>SPP were taken up by epithelial cells, macrophages, and dendritic cells. This uptake coincided with secretion of pro-inflammatory cytokines and chemokines. SP-D modulated the uptake of SPP in a cell type specific way (e.g. increased number of macrophages and epithelial cells, which participated in allergen particle uptake) and led to a decreased secretion of pro-inflammatory cytokines.</p> <p>Conclusion</p> <p>These results display a possible mechanism of how SP-D can modulate the inflammatory response to inhaled allergen.</p