House Dust Endotoxin and Allergic Sensitization in Children

Abstract

A higher exposure to endotoxin was hypothesized to contribute to lower prevalence of allergic sensitization and hay fever in children growing up on a farm. We studied the association between house dust endotoxin and allergic sensitization. We randomly selected 740 children, aged between 5 and 10 years, from a group of children who participated in two cross-sectional surveys performed in Saxony-Anhalt, Germany, from 1992 to 1993 and from 1995 to 1996, such that 50% of the children were atopic or had a diagnosis of asthma. From 1996 to 1998, we collected living-room floor dust in the homes of 454 of these children (61%). The content of endotoxin in house dust was quantified using a chromogenic kinetic limulus amoebocyte lysate test and was related with health outcomes measured in the preceding cross-sectional surveys. Multiple logistic regression analyses adjusted for place of residence, sex, age, parental education, parental atopy, and pet ownership showed a negative association between exposure to endotoxin and sensitization to one or more allergens (aOR [95% CI] 0.95 [0.83; 1.10]) and two or more allergens (aOR [95% CI] 0.80 [0.67; 0.97]) using 0.35 kU/L as the cutoff value for sensitization. The protective effect was strengthened with increasing degree of sensitization. In conclusion, exposure to higher levels of house dust endotoxin is associated with lower prevalence of allergic sensitization in children.

Endotoxin in inner-city homes: Associations with wheeze and eczema in early childhood

“…Inverse associations between endotoxin in house dust and allergic sensitization, eczema and atopic asthma in children have been reported (3,4,24,25), but have not been evaluated extensively in the inner-city communities of the United States. We have measured endotoxin in the homes of 301 children living in NYC.…”

“…Associations with allergic disease (both positive and negative) have been reported with endotoxin expressed both as a concentration and as a load (3,4,24,32,34), and we have analyzed our results throughout using both measures for comparison. The majority of the home characteristics and the only health effects significantly associated with endotoxin were observed with concentration of endotoxin.…”

Toll-like receptor 4 polymorphism and severity of atopy in asthmatics

“…5 Endotoxin, or lipopolysaccharide (LPS), is an extracellular component of the cell wall of Gramnegative bacteria. 4 Recent cohort studies in childhood have shown that higher levels of endotoxin in house dust and mattress dust are associated with a lower risk of allergic sensitisation 7,8 and atopic asthma. 9 Pattern recognition receptors sense endotoxin, and the innate immune system is activated via the endotoxin receptor complex, which includes LPS-binding protein, CD14, MD2 and Toll-like receptor 4 (TLR4).…”

Reproducibility of allergen, endotoxin and fungi measurements in the indoor environment

“…Bacterial endotoxin in indoor environment has also been suggested to play a role in the development of atopy and asthma. However, it is currently not clear whether endotoxin has a protective or inducing effect, or both, depending on timing and dose of exposure (Martinez and Holt, 1999;Gereda et al, 2000;Gehring et al, 2001Gehring et al, , 2002Park et al, 2001;Douwes et al, 2002). Longterm exposure to allergens, fungi and endotoxin is generally assessed by measuring these agents in house dust at one point in time.…”