Maternal Exposure to PM_2.5 Affects Fetal Lung Development at Sensitive Windows

Area of Science:

• Environmental Health
• Developmental Biology
• Toxicology

Background:

• Maternal exposure to atmospheric pollutants is linked to adverse respiratory outcomes in children.
• Experimental evidence demonstrating the impact of specific pollutants like PM2.5 on prenatal lung development is limited.

Purpose of the Study:

• To investigate the effects of maternal exposure to fine particulate matter (PM2.5) on prenatal lung development in mice offspring.
• To determine if PM2.5 exposure during gestation impacts fetal growth, lung organogenesis, and related gene expression.

Main Methods:

• Pregnant mice were exposed to PM2.5 via oropharyngeal aspiration every other day.
• Offspring were assessed for embryonic and fetal growth parameters (embryo weight, crown-rump length).
• Lung development, including branching morphogenesis, epithelial and mesenchymal differentiation, and gene expression (Nkx2.1, Tbx4, Tbx5, Sox9), was evaluated at specific embryonic stages (E18.5). Placental metal content and inflammation were also analyzed.

Main Results:

• Maternal PM2.5 exposure reduced embryo weight and crown-rump length at E18.5.
• While early lung development (E0-E16.5) was not overtly abnormal, exposure at E18.5 significantly disturbed distal lung epithelium and mesenchyme differentiation.
• Exposure led to reduced intact tracheal rings, suppressed key lung development gene expression, increased placental metal content (Pb, Cu), and induced placental inflammation.

Conclusions:

• Maternal PM2.5 exposure during sensitive prenatal periods adversely affects offspring lung development, particularly late-stage organogenesis.
• Placental accumulation of metals and inflammation serve as potential mechanisms mediating these developmental toxicities.
• Findings highlight the critical need to mitigate maternal exposure to air pollution for healthy fetal lung development.