Casas, LidiaTischer, ChristinaWouters, Inge M.Torrent Quetglas, MatiesGehring, UlrikeGarcía Esteban, RaquelThiering, ElisabethPostma, Dirkje S.de Jongste, JohanSmit, Henriëtte A.Borrás Santos, Alícia, 1974-Zock, Jan-PaulHyvärinen, AnneHeinrich, JoachimSunyer Deu, Jordi2015-11-252015-11-252013Casas L, Tischer C, Wouters IM, Torrent M, Gehring U, Garcia-Esteban R et al. Early life microbial exposure and fractional exhaled nitric oxide in school-age children: a prospective birth cohort study. Environ Health. 2013;12:103. DOI 10.1186/1476-069X-12-1031476-069Xhttp://hdl.handle.net/10230/25219BACKGROUND: Inflammation is a key factor in the pathogenesis of respiratory diseases. Early life exposure to microbial agents may have an effect on the development of the immune system and on respiratory health later in life.In the present work we aimed to evaluate the associations between early life microbial exposures, and fractional exhaled nitric oxide (FeNO) at school age. METHODS: Endotoxin, extracellular polysaccharides (EPS) and β(1,3)-D-glucan were measured in living room dust collected at 2-3 months of age in homes of participants of three prospective European birth cohorts (LISA, n = 182; PIAMA, n = 244; and INMA, n = 355). Home dampness and pet ownership were periodically reported by the parents through questionnaires. FeNO was measured at age 8 for PIAMA and at age 10/11 for LISA and INMA. Cohort-specific associations between the indoor microbial exposures and FeNO were evaluated using multivariable regression analyses. Estimates were combined using random-effects meta-analyses. RESULTS: FeNO at school age was lower in children exposed to endotoxin at age 2-3 months (β -0.05, 95% confidence interval (CI) -0.10;-0.01) and in children with reported dog ownership during the first two years of life (GM ratio 0.82, CI 0.70-0.96). FeNO was not significantly associated with early life exposure to EPS, β(1,3)-D-glucan, indoor dampness and cat ownership. CONCLUSION: Early life exposure to bacterial endotoxin and early life dog ownership are associated with lower FeNO at school age. Further studies are needed to confirm our results and to unravel the underlying mechanisms and possible clinical relevance of this finding.application/pdfeng© 2013 Casas et al.; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Aire ContaminacióPolisacàridsinfo:eu-repo/semantics/articlehttp://dx.doi.org/10.1186/1476-069X-12-103Cohort studyChildrenIndoorDampnessPetsBeta (1,3)-D-glucanExtracellular polysaccharidesEndotoxinFractional exhaled nitric oxideinfo:eu-repo/semantics/openAccess