title: Placental mitochondrial DNA content and particulate air pollution during in utero life.
abstract: BACKGROUND
  Studies emphasize the importance of particulate matter (PM) in the formation of reactive oxygen species and inflammation. We hypothesized that these processes can influence mitochondrial function of the placenta and fetus.
  
  
  OBJECTIVE
  We investigated the influence of PM₁₀ exposure during pregnancy on the mitochondrial DNA content (mtDNA content) of the placenta and umbilical cord blood.
  
  
  METHODS
  DNA was extracted from placental tissue (n = 174) and umbilical cord leukocytes (n = 176). Relative mtDNA copy numbers (i.e., mtDNA content) were determined by real-time polymerase chain reaction. Multiple regression models were used to link mtDNA content and in utero exposure to PM₁₀ over various time windows during pregnancy.
  
  
  RESULTS
  In multivariate-adjusted analysis, a 10-µg/m³ increase in PM₁₀ exposure during the last month of pregnancy was associated with a 16.1% decrease [95% confidence interval (CI): -25.2, -6.0%, p = 0.003] in placental mtDNA content. The corresponding effect size for average PM₁₀ exposure during the third trimester was 17.4% (95% CI: -31.8, -0.1%, p = 0.05). Furthermore, we found that each doubling in residential distance to major roads was associated with an increase in placental mtDNA content of 4.0% (95% CI: 0.4, 7.8%, p = 0.03). No association was found between cord blood mtDNA content and PM₁₀ exposure.
  
  
  CONCLUSIONS
  Prenatal PM₁₀ exposure was associated with placental mitochondrial alterations, which may both reflect and intensify oxidative stress production. The potential health consequences of decreased placental mtDNA content in early life must be further elucidated.
authors.affiliation: Centre for Environmental Sciences, Hasselt University, Diepenbeek, Belgium.
authors.forename: Bram G
authors.initials: BG
authors.lastname: Janssen
authors.forename: Elke
authors.initials: E
authors.lastname: Munters
authors.forename: Nicky
authors.initials: N
authors.lastname: Pieters
authors.forename: Karen
authors.initials: K
authors.lastname: Smeets
authors.forename: Bianca
authors.initials: B
authors.lastname: Cox
authors.forename: Ann
authors.initials: A
authors.lastname: Cuypers
authors.forename: Frans
authors.initials: F
authors.lastname: Fierens
authors.forename: Joris
authors.initials: J
authors.lastname: Penders
authors.forename: Jaco
authors.initials: J
authors.lastname: Vangronsveld
authors.forename: Wilfried
authors.initials: W
authors.lastname: Gyselaers
authors.forename: Tim S
authors.initials: TS
authors.lastname: Nawrot
mesh_terms: D000293:Adolescent; D000328:Adult; D000393:Air Pollutants / Q000633:toxicity*; D015331:Cohort Studies; D004272:DNA, Mitochondrial / Q000097:blood*; D004781:Environmental Exposure; D005260:Female; D005312:Fetal Blood / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D015999:Multivariate Analysis; D009426:Netherlands; D018384:Oxidative Stress; D052638:Particulate Matter / Q000633:toxicity*; D010920:Placenta / Q000187:drug effects* / Q000378:metabolism; D011247:Pregnancy; D060888:Real-Time Polymerase Chain Reaction; D013997:Time Factors; D001335:Vehicle Emissions / Q000633:toxicity*; D055815:Young Adult
chemical_list: D000393:Air Pollutants; D004272:DNA, Mitochondrial; D052638:Particulate Matter; D001335:Vehicle Emissions