Project 3: Role of cytochrome P450 (CYP)1A/1B1 enzymes in the potentiation of neonatal lung injury in newborn mice exposed prenatally to PAHs, and increased risk of premature infants to chronic lung disease

Pregnant women living in the vicinity of Superfund sites, who may be exposed to polycyclic aromatic hydrocarbons (PAHs) that emanate from these sites, are at a higher risk for preterm delivery. Preterm delivery requires the neonate to be subjected to supplemental oxygen (hyperoxia), and this, in turn, could lead to chronic lung disease / bronchopulmonary dysplasia (BPD). The researchers hypothesize that prenatal PAH exposure exacerbates the effects of postnatal supplemental oxygen in preterm neonates. The mechanisms by which PAHs potentiate BPD in infants are not well understood.

The central hypothesis of this project is that prenatal administration of PAHs [i.e., benzo[a]pyrene (BP) or a mixture of benzo(a)pyrene (BP), benzo(b)fluoranthrene (BbF), and dibenz[a]anthracene (DBA)], which are defined as class B2 carcinogens by the U.S. Environmental Protection Agency, differentially exacerbates lung injury and alveolar simplification in neonatal mice following postnatal hyperoxia and that this effect is altered in mice lacking the gene for cytochrome P450 (Cyp)1a1 or 1a2 genes by mechanisms entailing a combination of genotoxic and epigenetic mechanisms. The researchers are also testing the hypothesis that the infants exposed prenatally to PAHs have a greater risk of developing BPD than those exposed to lesser or no PAHs and that human pulmonary cells exposed to remediated PAHs exhibit lesser toxicity than parent PAHs. In order to test these hypotheses, the researchers propose the following specific aims:

• Test the hypothesis that prenatal exposure of wild type (WT) (C57BL/6J) mice to the PAH BP or a mixture of PAHs (BP + BbF + DBA) results in exacerbation of lung injury and alveolar simplification following postnatal hyperoxia – and this effect is altered in mice lacking the gene for Cyp1a1, 1a2 or 1b1.
• Determine the mechanisms by which prenatal PAHs alter the susceptibility of neonatal mice to hyperoxia.
• Test the hypothesis that mothers exposed to PAHs (that are present in Superfund sites) are at a greater risk for preterm delivery and that these infants show increased susceptibility to develop BPD than those with lesser or no exposure.

Accomplishments of these aims could lead to novel strategies for the prevention/treatment in premature infants of BPD, which is probably potentiated by maternal PAHs that emanate from Superfund sites.