Toxicity and transcriptome sequencing analyses of nanoplastics combined with acetaminophen on zebrafish bone...

Congenital spinal malformation, a significant birth defect with unclear etiology, has been increasingly associated with environmental factors in recent studies. This research focuses on the effects of two emerging environmental pollutants, nanoplastics (NPs) and acetaminophen (APAP), on spinal development. Using a juvenile zebrafish model, we systematically evaluated the toxic effects and transcriptomic alterations induced by individual and combined exposure to two pollutants. Specifically, we assessed variations in spinal morphology and bone mineral density parameters across different treatment groups through calcein fluorescence staining and three-dimensional micro-CT imaging. Our findings demonstrate that APAP exposure alone significantly induces spinal abnormalities, such as scoliosis and bone defects. Interestingly, co-exposure with NPs indicated lower toxic effects. Transcriptome sequencing analyses suggested that APAP may disrupt bone development homeostasis by interfering with endoplasmic reticulum protein processing, Wnt and BMP signaling pathways, and the expression of key osteogenic genes. Compared with sole exposure to APAP, the composite exposure to both NPs and APAP significantly reversed the inhibitory state of genes such as runx3, tbx6, sox9b, and bmpr2b in the core pathway of bone development and weakened the transcriptional interference of wnt7bb and plcd1b, indicating that the overall transcriptional disturbance intensity of APAP on the bone development network is reduced under composite exposure conditions. This study provides experimental evidence that NPs can mitigate the skeletal developmental toxicity induced by APAP, as confirmed by both phenotypic reversal and transcriptomic data. The qRT-PCR validation confirmed the downregulation of key osteogenic genes (e.g., tbx6, wnt7aa, bmpr2b) under APAP exposure and their recovery under co-exposure conditions. These findings provide novel insights into the complex interactions among environmental pollutants and their implications for the etiology of congenital spinal malformations.