676 Introduction he link between elevated concentrations of air pollution and adverse public health efects is now well established. Increased levels of particulate matter (PM10 and PM2.5) are widely recognized for their causal contribution to mortality and cardiovascular morbidity and mortality (Pope et al., 2009; Brook et al., 2010). Important legislative eforts have been made in most industrialized countries to reduce emissions of pollutants and to determine safe levels. Although it remains unclear which pollutants or fraction of particles are driving the health efects that are identiied in epidemiological studies, strong circumstan- tial evidence indicates that traic plays an important role. In addition, evidence is accumulating that exposure to air pollution can cause brain damage and neurodegeneration. Long-term exposure to air pollution is associated with neuroinlammation and a disruption of the blood-brain barrier (Calderón-Garcidueñas RESEARCH ARTICLE Changed gene expression in brains of mice exposed to traic in a highway tunnel Inge Bos 1,2 , Patrick De Boever 1,3 , Jan Emmerechts 4,5 , Jurgen Buekers 1 , Jeroen Vanoirbeek 5 , Romain Meeusen 2 , Martine Van Poppel 1 , Benoit Nemery 5 , Tim Nawrot 3,5 , and Luc Int Panis 1,6 1 Flemish Institute for Technological Research (VITO), Mol, Belgium, 2 Department of Human Physiology & Sports Medicine, Vrije Universiteit Brussel, Brussels, Belgium, 3 Centre for Environmental studies (CMK), Hasselt University, Diepenbeek, Belgium, 4 Center for Molecular and Vascular Biology, University of Leuven, Belgium, 5 Department of Public Health, Occupational and Environmental Medicine, Unit of Lung Toxicology, University of Leuven, Leuven, Belgium, and 6 Transportation Research Institute (IMOB), Hasselt University, Diepenbeek, Belgium Abstract Context: Air pollution has been suggested to have an impact on the brain. Objective: The objective was to assess the expression of inlammation-related genes in the brains of mice that had been exposed for 5 days to a well-characterized traic-polluted environment, i.e. a highway tunnel. Materials and methods: Twenty C57BL6 mice were randomly allocated to four groups of ive animals. Two groups were placed in the tunnel for 5 days (mean PM 2.5, 55.1 μg/m 3 , mean elemental carbon, EC 13.9 μg/m 3 ) in cages with or without ilter, two control groups were housed outside the tunnel. Animals were assessed within 24 hours after the last exposure day. Lung injury and inlammation were assessed by bronchoalveolar lavage (BAL) and histology. Blood leukocytosis and coagulation parameters were determined in peripheral blood. The olfactory bulb and hippocampus were analyzed for changes in expression of inlammatory genes and brain-derived neurotrophic factor (BDNF). Results and discussion: Although carbon particles were abundant in alveolar macrophages of exposed mice and absent in non-exposed mice, there was no evidence of pulmonary or systemic inlammation. There was an increased expression of genes involved in inlammatory response (COX2, NOS2, NOS3, and NFE2L2) in the hippocampus of the exposed mice. In the olfactory bulb, a downregulation was found for IL1α, COX2, NFE2L2, IL6, and BDNF. Conclusion: Although this short-term exposure to traic-related pollution did not induce pulmonary or systemic inlammation, the expression of inlammatory genes was afected in diferent brain areas. The decreased BDNF expression in the olfactory bulb suggests lower brain neurotrophic support in response to traic-related air pollution. Keywords: Particulate matter, black carbon, brain-derived neurotrophic factor (BDNF), inlammation, hippocampus, olfactory bulb, blood, bronchoalveolar lavage (BAL), lung Address for Correspondence: Luc Int Panis, VITO, Environment and Health, Boeretang 200, 2400 Mol, Belgium. Tel: +32 14 335102. Fax: +32 14 58 26 57. E-mail: luc.intpanis@vito.be (Received 31 May 2012; revised 11 July 2012; accepted 17 July 2012) Inhalation Toxicology, 2012; 24(10): 676–686 © 2012 Informa Healthcare USA, Inc. ISSN 0895-8378 print/ISSN 1091-7691 online DOI: 10.3109/08958378.2012.714004 Inhalation Toxicology Downloaded from informahealthcare.com by Vito on 08/21/12 For personal use only.