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P333. Endotoxin levels and juvenile inflammatory bowel disease – A case–control study

A. Boneberger1, C. Hangl1, R. Schierl1, S. Koletzko1, R. von Kries2, M. Kabesch3, K. Radon1

1Hospital of the Ludwig-Maximilians-University Munich, Munich, Germany; 2Ludwig-Maximilians-University Munich, Munich, Germany; 3Hannover Medical School, Hannover, Germany

Aim: It is suggested that asthma and IBD share the same pathogenesis or genetic background. Animal contact may reduce the risk not only for allergic diseases but also for inflammatory bowel diseases (IBD). We aimed to clarify the relationship between endotoxin levels in the home environment and the association with IBD.

Materials and Methods: An age- and sex-matched case–control study including 85 cases (aged: 8–29 years) and 91 controls (aged: 11–23 years) was conducted in Bavaria, Southern Germany. A questionnaire and a dust sampling sock (Allied Filter Fabrics Pty. Ltd., Sydney, Australia) were mailed to the parents (Response: 71% among cases, 58% among controls). Endotoxin levels were determined using a chromogenic kinetic LAL assay (Lonza). Results (EU/mg dust) are presented as interquartile range increase and in quartiles. Logistic regression models adjusting for age, sex, urban place of living, environmental factors in the first year of life (tobacco smoke exposure, living on a farm, pet and animal contact), high parental education and family history of inflammatory bowel disease were performed.

Results: Geometric mean levels of endotoxin were lower among cases (50.7 Endotoxin Units (EU)/mg; geometric standard deviation (GSD); 2.3) than controls (60.3 EU/mg; GSD: 2.2). Pravalence of IBD decreased with increasing endotoxin levels. In the final multivariate logistic regression analysis the adjusted Odds Ratio for IBD for interquartile range increase in Endotoxins was 0.7; 95% Confidence Interval: 0.5–1.0). We found a consistent inverse dose-response association with endotoxin quartiles for all IBD cases. Stratifying for CD and UC results remained consistent.

Conclusion: Our results back up the hypothesis that similar environmental factors might be associated with both asthma and IBD. To date, the final pathomechanisms how endotoxin levels might decrease the occurrence of asthma and IBD remain unclear. Epidemiological data from asthma studies suggest that a decreased exposure to pathogenic infectious agents especially early in life could lead to an inappropriate inflammatory process, such as asthma or IBD. Whether endotoxin is a marker of hygiene or causal has to be evaluated in future studies.