Temporal dynamics of macrophages transcriptional profiles during zebrafish wound healing

Macrophages participate to wound healing by contributing to host defense and orchestrating inflammation and repair. They adapt dynamically to the wound microenvironment by adopting diverse polarization states, which are determinant of wound outcome, influencing whether healing is successful or becomes chronic. The zebrafish embryo, widely used for live imaging of immune responses, is a powerful model to study macrophage behavior after injury. However, the transcriptional landscape of polarized macrophages in this model during wound healing remains insufficiently characterized. Here, we employ bulk RNA sequencing to characterize macrophage transcriptional programs following tail fin wounding a robust model for studying sterile inflammation. Our findings reveal that zebrafish macrophages undergo large transcriptomic changes along different wound healing phases, particularly between 2 and 5 hours post-amputation, suggesting a fast reprogramming leading to different functional states. We further show that, at 2h, macrophages acquire a pro-inflammatory profile with a gene signature closed to M1 signature. At 5h, macrophages express genes involved in immunoregulation and healing associated with shutoff of pro-inflammatory pathways and the activation of glucose and glycogen metabolism. Finally, we show that macrophage reprogramming becomes deeply attenuated by 29h. Our findings provide a foundation for understanding macrophage polarization in zebrafish, revealing underpinning molecular mechanisms, including both specific and evolutionarily conserved pathways with a potential impact on translational medicine.