GSE174529
New insights into benzo[?]pyrene osteotoxicity in zebrafish
Persistent and ubiquitous organic pollutants, such as the polycyclic aromatic hydrocarbon benzo[?]pyrene (BaP), represent a major threat to aquatic organisms and human health. Beside some well-documented adverse effects on the development and reproduction of aquatic organisms, BaP was recently shown to affect fish bone formation and skeletal development through mechanisms that remain poorly understood. In this work, several bone-related in vivo assays were used in zebrafish to evaluate the osteotoxic effects of BaP during bone development and regeneration. Exposure to BaP for 3 days induced a dose-dependent reduction of the size of the opercular bone in 6 days post-fertilization (dpf) larvae, and affected osteoblast maturation as observed by the expression of the mature marker, osteocalcin. Exposure to BaP for 27 days affected the development of the axial skeleton and increased the incidence and severity of skeletal deformities. During bone regeneration, BaP affected the mineralization of newly formed fin rays and scales, while it impaired fin ray patterning and scale shape, through mechanisms that may involve an imbalance of bone remodeling. Transcriptomic and gene expression analyses indicate that BaP induced the activation of xenobiotic and metabolic pathways, while negatively impacting extracellular matrix formation and organization. Interestingly, BaP exposure positively regulated inflammation markers in 6 dpf larvae and increased neutrophil recruitment. A direct interaction between neutrophils and bone extracellular matrix or bone forming cells was observed in vivo, suggesting a role for neutrophils in the mechanisms underlying BaP osteotoxicity. Our work provides novel data on the cellular and molecular players involved in BaP osteotoxicity and brings new insights into a possible role for neutrophils in inflammatory bone reduction. Overall design: Whole-larvae mRNA profiles of 6 day post fertilization (dpf) wild type zebrafish strain AB, treated either with DMSO 0.1% or benzo(a)pyrene 1 µM from 3 to 6 dpf