Endotoxin Exposure Is a Risk Factor for Asthma: the National Survey of Endotoxin in United States Housing

Department of Occupational and Environmental Health, College of Public Health, University of Iowa, 100 Oakdale Campus, 176 IREH, Iowa City, IA 52242-5000, USA.
American Journal of Respiratory and Critical Care Medicine (Impact Factor: 13). 01/2006; 172(11):1371-7. DOI: 10.1164/rccm.200505-758OC
Source: PubMed


Although research has shown that early life exposure to household endotoxin protects against development of allergies, studies are less clear on the relationship between household endotoxin exposure and prevalence of wheezing and asthma. We assayed 2,552 house dust samples in a representative nationwide sam- ple to explore relationships between endotoxin exposures and risk factors for asthma, asthma symptoms, and medication use.
House dust was vacuum-sampled from five locations within homes and assayed for endotoxin. Health, demographic, and housing information was assessed through questionnaire and on-site evaluation of 2,456 residents of 831 homes selected to represent the demographics of the United States.
Endotoxin concentration (EU/mg) and load (EU/m(2)) were highly correlated (r = 0.73-0.79). Geometric mean endotoxin concentrations were as follows (in EU/mg): bedroom floors, 35.3 (5th-95th percentile, 5.0-260); bedding, 18.7 (2.0-142); family room floors, 63.9 (11.5-331); sofas, 44.8 (6.4-240); and kitchen floors, 80.5 (9.8-512). Multivariate analysis demonstrated significant relationships between increasing endotoxin levels and diagnosed asthma, asthma symptoms in the past year, current use of asthma medications, and wheezing among residents of the homes. These relationships were strongest for bedroom floor and bedding dust and were observed in adults only. Modeling the joint effect of bedding and bedroom floor endotoxin on recent asthma symptoms yielded an adjusted odds ratio of 2.83 (95% confidence interval, 1.01-7.87). When stratified by allergy status, allergic subjects with higher endotoxin exposure were no more likely to have diagnosed asthma or asthma symptoms than nonallergic subjects.
This study demonstrates that household endotoxin exposure is a significant risk factor for increased asthma prevalence.

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    • "Some well known environmental triggers of asthma are smoke, particulate matters, pollutants and bacterial or viral infections [2]. LPS a major component of the outer membrane of gram-negative bacteria and its exposure is a major risk factor for asthma as studies have shown strong relationship between levels of household LPS and asthma exacerbations [3]. Gram negative bacterial infections like Chlamydia, Mycoplasma, and Haemophilus influenzae are most frequently associated with asthmatic exacerbations. "
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    ABSTRACT: Lipopolysaccharide (LPS) is ubiquitous in the environment and can therefore, exacerbate allergic responses. Studies have suggested immunoregulatory effects of LPS according to route, dose and stage of exposure. Present study has examined whether dose and stage of LPS exposure (during sensitization and challenge with OVA) exacerbates airway inflammations, antigen specific-IgE level, histamine release, Th1/Th2 cytokine response. Further, anti-asthmatic potential of curcumin, through intranasal route has been evaluated for the first time in LPS induced airway inflammation in an ovalbumin (OVA)-challenged mouse asthma model. Balb/c mice were first sensitized with OVA on 1st and 8th day and exposed to two LPS doses (0.1/1.0μg) separately on 2nd day and then further exposed to LPS with OVA-aerosol (from 9 to 14day). Further, lower LPS dose (0.1μg) was chosen for OVA exposed mouse model of asthma exacerbation study. Intranasal curcumin was administered from 9th to 14th day before every LPS exposure. Exposure to LPS (0.1μg) exacerbates airway inflammations in terms of IgE level, Th2-cytokine response (IL-4 and IL-5), histamine release, EPO and MPO activities and oxidative stress. Intranasal curcumin has effectively ameliorated airway exacerbations whereas dexamethasone, a known glucocorticosteroid, was not promising as compared to intranasal curcumin. Schedule and dose of LPS exposure determines asthma exacerbations and intranasal curcumin could be better immunomodulatory agent in LPS exposed asthma exacerbations. Copyright © 2015. Published by Elsevier Ltd.
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    • "Epidemiological studies suggest that endotoxin levels in samples from children’s mattress were inversely related to the occurrence of atopic asthma [13]. On the other hand, some other studies have shown that endotoxin exposure is positively associated with an increased risk of asthma and asthma severity in both adults and children [14,15]. The results of animal studies are also somewhat contradictory. "
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    • "They are adsorbed on the surface of particles and are found to be mostly associated with coarse PM (Soukup and Becker, 2001; Schins et al., 2004). When inhaled, endotoxin can contribute to asthma exacerbation in children (Rizzo et al., 1997), and increased prevalence and severity of asthma in adults (Michel et al., 1996; Thorne et al., 2005). A number of studies have demonstrated the association of endotoxin exposure with proinflammatory cytokine production (Monn and Becker, 1999; Becker and Soukup, 1999), increased lung inflammation, airway responsiveness and systemic immune cell populations (Michel et al., 1996), and lung function modification by CD14/À260 genotype (Bakolis et al., 2012). "
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