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Background: Domestic endotoxin enhances airway inflammation and increases asthma severity in Caucasian children, but little data are published on indoor endotoxin exposure in Asian countries. This study investigated house dust endotoxin and Der p 1 levels in Hong Kong families with asthmatic children, and their effects on asthma severity. Methods: 115 asthmatics from a pediatric clinic underwent fractional exhaled nitric oxide (FeNO) and spirometric measurements. Home visits were then made within 2 weeks, during which parents completed the International Study of Asthma and Allergies in Childhood questionnaire. Settled dust was collected from patients’ mattresses, bedroom floors and living room floors. Endotoxin and Der p 1 were measured by limulus amebocyte lysate and immunoassay, respectively. Results: Endotoxin was detectable in all locations from all families, whereas Der p 1 was detectable in 58–70% of indoor sites. Floors of both bedroom and living rooms had higher endotoxin but lower Der p 1 levels than mattresses (p < 0.001 for both). Mattress endotoxin level correlated inversely with Der p 1 level (r = –0.308, p = 0.001). Household smoker, feather bedding and vacuum cleaning were independent determinants of indoor endotoxin. Timing of last bedding change was associated with Der p 1 levels at all sites. Mattress endotoxin level was associated with frequency of wheezing episodes (p = 0.044), but neither endotoxin nor Der p 1 was associated with FeNO and spirometric parameters. Conclusions: Domestic endotoxin levels are associated with frequency of wheezing episodes in asthmatic children but not their FeNO or spirometric measurements. Copyright © 2010 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: Vascular endothelial growth factor (VEGF), AA isoform of platelet-derived growth factor (PDGF-AA), and epidermal growth factor (EGF) are involved in the pathogenesis of airway inflammation in asthma. These molecules are closely associated with cytokines such as tumor necrosis factor-α (TNF-α) and interleukin (IL)-4. This study investigates the relation between childhood asthma and levels of these mediators in exhaled breath condensate (EBC). Methods: EBC was collected from asthmatic children and controls using a disposable collection kit, and the concentrations of VEGF, PDGF-AA, EGF, TNF-α and IL-4 in EBC were measured using sandwich enzyme immunoassays. Exhaled nitric oxide concentration was measured by a chemiluminescence analyzer. Results: Thirty-five asthmatic patients aged between 7 and 18 years and 11 controls were recruited. Sixteen patients had intermittent asthma (IA) whereas 19 of them suffered from persistent asthma (PA). A significant correlation was found between IL-4 and TNF-α in EBC (ρ = 0.374, p = 0.010). PDGF-AA levels in EBC were higher in subjects with diminished FEV1 (p = 0.023) whereas IL-4 concentrations were increased in asthmatics (p = 0.007) as well as subjects with increased plasma total IgE (p = 0.033). Patients with PA receiving high-dose inhaled corticosteroid (ICS) had higher EBC IL-4 concentration than those on low-dose ICS (p = 0.007). Linear regression revealed that PDGF-AA levels in EBC were negatively associated with FEV1 percentage (β = –0.459, p = 0.006) among the asthmatic patients. Conclusions: IL-4 in EBC is increased in childhood asthma, and growth factors are detectable in a significant proportion of these children. Increased PDGF-AA is found in asthmatics with more severe airflow limitation. Copyright © 2005 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]