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Paternal exposure to polystyrene nanoplastics induces inter- and transgenerational bronchopulmonary dysplasia-like damage in male offspring by FtMt hypermethylation-mediated ferroptosis.
Summary
A new mouse study found that when fathers were exposed to nanoplastics (tiny plastic particles found in everyday products), their sons and grandsons were born with damaged, underdeveloped lungs, similar to a serious condition seen in premature babies. The plastics changed chemical "tags" on the father's sperm DNA that lowered a protective gene, allowing iron to build up in lung cells and damage them, and this harmful change passed down for two generations. While this research is in mice, not humans, it raises concerns that a father's plastic exposure before conception could affect his children's and grandchildren's lung health.
Bronchopulmonary dysplasia (BPD) is a major cause of chronic lung disease in both preterm infants and adults, but its etiology remains incompletely understood. In this study, F0 generation mice were exposed to polystyrene nanoplastics (PS-NPs), and F1 to F3 generations were obtained by breeding. Multi-omics sequencing including whole genome methylation sequencing, single cell transcriptome sequencing and transcriptome sequencing was performed on the lungs of offspring. The levels of Fe, lipid peroxidation products and key gene expression were determined. Male mice exposed to PS-NPs at environmentally relevant doses produced offspring (F1 and F2) that exhibited a typical BPD-like phenotype. Meanwhile, the F0 males showed diminished sperm motility, demonstrating that paternal PS-NPs exposure constituted an etiological factor for BPD in descendants. Mechanistic studies showed that PS-NPs exposure upregulated the expression of DNA methyltransferase Dnmt3a, leading to global hypermethylation of the sperm genome. Importantly, the hypermethylated promoter signature of the mitochondrial ferritin (FtMt) gene partially resisted epigenetic reprogramming and was transmitted to the lungs of offspring, resulting in persistently low FtMt expression in F1 and F2 lungs. This led to increased intracellular Fe levels, subsequently triggered ferroptosis in alveolar epithelial cells, and ultimately impaired alveolarization. Knockdown of FtMt confirmed that FtMt deficiency was sufficient to induce ferroptosis and BPD-like lung injury both in vitro and in vivo. Furthermore, using in vitro fertilization of F0 sperm combined with Dnmt3a siRNA microinjection, we directly demonstrated that Dnmt3a is a key driver for FtMt to escape reprogramming and maintain its hypermethylation. In summary, this study reveals for the first time that paternal PS-NPs exposure causes BPD through a Dnmt3a-FtMt hypermethylation intergenerational and transgenerational axis, providing an epigenetic basis for understanding paternal derived chronic lung disease and potential targets for early intervention.