Zhuowei Li

Background/Objectives: Acetaminophen (APAP) is used during 50–60% of pregnancies in the U.S. and has been associated with childhood respiratory morbidity, though the underlying mechanism remains unclear. APAP-induced injury is dependent on cell-specific expression of CYP2E1, the enzyme that metabolizes APAP into the mitochondrial toxin NAPQI. In mice, pulmonary Cyp2e1 expression peaks during the saccular stage of lung development on embryonic day 18 (E18). We investigated whether this developmental surge in Cyp2e1 triggers a pulmonary transcriptional response to maternal APAP exposure in embryonic lungs. Methods: Pregnant dams were exposed to APAP on E17 or E18 (150 or 250 mg/kg, IP) using doses derived from prior studies. We assessed the induction of NRF2 target genes and genes associated with inflammation, apoptosis and cellular stress due to their roles in APAP-induced oxidative and cellular stress. Results: At E17, maternal treatment with APAP induced pulmonary Cyp2e1 but resulted in inconsistent transcriptional changes. In contrast, maternal APAP at E18 triggered a robust transcriptional induction of Cyp2e1, NRF2 targets and markers of apoptosis, inflammation and cellular stress. Histopathology at birth after E18 APAP exposure revealed no acute pulmonary injury. Conclusions: We demonstrate a developmentally regulated, dose-dependent transcriptional response to maternal APAP in the embryonic murine lung. Importantly, transcriptional responses do not directly indicate lung injury; thus, future studies should assess protein-level changes following APAP exposure. This study underscores the need for further investigation into the role of developmentally regulated Cyp2e1 expression in APAP-induced toxicity and long-term respiratory morbidity.

A major barrier to the impact of genomic diagnosis in patients with congenital malformations is the lack of understanding regarding how sequence variants contribute to disease pathogenesis and whether this information could be used to generate patient-specific therapies. Congenital diaphragmatic hernia (CDH) is among the most common and severe of all structural malformations; however, its underlying mechanisms are unclear. We identified loss-of-function sequence variants in the epigenomic regulator geneSIN3Ain two patients with complex CDH. Tissue-specific deletion ofSin3ain mice resulted in defects in diaphragm development, lung hypoplasia, and pulmonary hypertension, the cardinal features of CDH and major causes of CDH-associated mortality. Loss of SIN3A in the lung mesenchyme resulted in reduced cellular differentiation, impaired cell proliferation, and increased DNA damage. Treatment of embryonicSin3amutant mice with anacardic acid, an inhibitor of histone acetyltransferase, reduced DNA damage, increased cell proliferation and differentiation, improved lung and pulmonary vascular development, and reduced pulmonary hypertension. These findings demonstrate that restoring the balance of histone acetylation can improve lung development in theSin3amouse model of CDH.