Associations between household endotoxin exposure and atopic dermatitis: A cross-sectional U.S.-based population study

Summary: Abstract Body: Endotoxin exposure has been shown to be protective against allergic disease in early childhood by promoting a Th1 phenotype. Endotoxins can exacerbate a Th2 immune response and asthma later in life, though research on its effect in adulthood on atopic dermatitis (AD) is limited. The objective of our study was to investigate endotoxin predictors and their allergy-associated outcomes across the lifespan. Using the National Health and Nutrition Examination Survey (NHANES) 2005-2006 dataset, we analyzed data from 7,450 participants aged 1-85 years, including cross-sectional questionnaires and dust sample analyses. Linear and multivariate logistic regression analyses were conducted using R to identify endotoxin predictors and their associations with AD. Demographic analysis revealed that males had 26% lower odds of AD prevalence compared to females (OR: 0.74, 95% CI: 0.57-0.94, p=0.016). Non-Hispanic White and Black individuals showed higher odds of AD prevalence compared to Hispanic individuals (OR: 3.00, 95% CI: 1.59-6.42, p=0.002; OR: 2.67, 95% CI: 1.38-5.80, p=0.007, respectively). The median endotoxin concentration in house dust among AD patients was 42.6 EU/mg, higher than the overall population. Individuals with asthma history exhibited increased odds of AD (OR: 1.78, 95% CI: 1.13-2.72, p=0.010), as did those with hay fever history (OR: 1.64, 95% CI: 1.00-2.61, p=0.043). Interestingly, cockroach presence was associated with 57% lower odds of AD prevalence (OR: 0.43, 95% CI: 0.23-0.75, p=0.005). Endotoxin predictors, including higher house dust endotoxin levels, asthma, and hay fever, were associated with increased AD prevalence, while cockroach presence showed an inverse relationship. In particular, AD prevalence was influenced by factors affecting females and non-Hispanic individuals. These findings highlight the complex interplay of exposomal factors, racial diversity, and age in AD development, emphasizing the need for further research into endotoxins and environmental pollutants to guide targeted prevention strategies. Irene L. Quan¹, Liza Yusem Carstens¹, Peter Lio¹ 1. Dermatology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States. Innate Immunity, Microbiology, and Microbiome