title: In Utero Fine Particle Air Pollution and Placental Expression of Genes in the Brain-Derived Neurotrophic Factor Signaling Pathway: An ENVIRONAGE Birth Cohort Study.
abstract: BACKGROUND
  Developmental processes in the placenta and the fetal brain are shaped by the same biological signals. Recent evidence suggests that adaptive responses of the placenta to the maternal environment may influence central nervous system development.
  
  
  OBJECTIVE
  We studied the association between in utero exposure to fine particle air pollution with a diameter ≤ 2.5 μm (PM2.5) and placental expression of genes implicated in neural development.
  
  
  METHODS
  Expression of 10 target genes in the brain-derived neurotrophic factor (BDNF) signaling pathway were quantified in placental tissue of 90 mother-infant pairs from the ENVIRONAGE birth cohort using quantitative real-time polymerase chain reaction. Trimester-specific PM2.5 exposure levels were estimated for each mother's home address using a spatiotemporal model. Mixed-effects models were used to evaluate the association between the target genes and PM2.5 exposure measured in different time windows of pregnancy.
  
  
  RESULTS
  A 5-μg/m3 increase in residential PM2.5 exposure during the first trimester of pregnancy was associated with a 15.9% decrease [95% confidence interval (CI): -28.7, -3.2%, p = 0.015] in expression of placental BDNF at birth. The corresponding estimate for synapsin 1 (SYN1) was a 24.3% decrease (95% CI: -42.8, -5.8%, p = 0.011).
  
  
  CONCLUSIONS
  Placental expression of BDNF and SYN1, two genes implicated in normal neurodevelopmental trajectories, decreased with increasing in utero exposure to PM2.5. Future studies are needed to confirm our findings and evaluate the potential relevance of associations between PM2.5 and placental expression of BDNF and SYN1 on neurodevelopment. We provide the first molecular epidemiological evidence concerning associations between in utero fine particle air pollution exposure and the expression of genes that may influence neurodevelopmental processes.
authors: Centre for Environmental Sciences, Hasselt University, Diepenbeek, Limburg, Belgium.
authors: Nelly D
authors: ND
authors: Saenen
authors: Michelle
authors: M
authors: Plusquin
authors: Esmée
authors: E
authors: Bijnens
authors: Bram G
authors: BG
authors: Janssen
authors: Wilfried
authors: W
authors: Gyselaers
authors: Bianca
authors: B
authors: Cox
authors: Frans
authors: F
authors: Fierens
authors: Geert
authors: G
authors: Molenberghs
authors: Joris
authors: J
authors: Penders
authors: Karen
authors: K
authors: Vrijens
authors: Patrick
authors: P
authors: De Boever
authors: Tim S
authors: TS
authors: Nawrot
mesh_terms: D000328:Adult; D000393:Air Pollutants / Q000032:analysis*; D001530:Belgium; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics* / Q000378:metabolism; D015331:Cohort Studies; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D010920:Placenta / Q000187:drug effects* / Q000378:metabolism; D011247:Pregnancy; D011264:Pregnancy Trimesters; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects*; D055815:Young Adult
chemical_list: D000393:Air Pollutants; D019208:Brain-Derived Neurotrophic Factor; D052638:Particulate Matter; C579455:BDNF protein, human