Enhanced Vulnerability Of The Developing Lungs By Moderate Prenatal Cigarette Smoke Upon Postnatal Injury

Neonatal chronic lung disease (nCLD) in preterm infants, also known as bronchopulmonary dysplasia (BPD) is one of the major complications arising in the premature infant. Preand postnatal stressors, such as mechanical ventilation (MV) and hyperoxia (O2) are known to contribute to disease development. In our study we observed that moderate prenatal cigarette smoke (pCS), enhances the vulnerability of the developing lung to postnatal injury resulting in impaired septation and vessel growth along with disturbed platelet drive growth factor (PDGF) signaling and extracellular matrix (ECM) remodeling. We hypothesized that pCS increases the development of adverse effects in response to postnatal injury (oxygen or mechanical ventilation) thereby impairing lung development in neonatal mice. The study specifically focused on histologic endpoints, i.e. the formation of alveoli and vessels in the face of altered growth factor signaling. Methods Female C57BL/6 (WT) and transgenig mice (8–10-weeks old) were exposed to CS from day 7 to day 18 of pregnancy. Smoke was generated from 3R4F Research Cigarettes (Tobacco Research Institute, University of Kentucky,Lexington, KY, U.S.A.). The chamber atmosphere was monitored to maintain 500 mg/m CS and mice were exposed to CS for 50 min twice per day. Control mice were kept in a filtered air (FA) environment. 5-8 days C57B6 (WT) mice from both groups (FA and pCS) either received mechanical ventilation (MV-O2), hyperoxia (O2; fiO2=0.4) or room air (RA; fiO2=0.21) for 8 hours. Lungs collected from these neonatal mice were subjected to histologic analysis including alveolar and micro-vessel number (20-100 μm), assessment of apoptosis (TUNEL and cleaved-caspase-3 staining) and immunoblot analysis for growth factors and vessel markers. PDGF-Rα haploinsufficient neonatal mice (Charles River) were subjected to the RA and hyperoxia model described above to unravel the potential role of the growth factor in this context.