Post traumatic response of coelomocytes in the common sea star Echinaster sepositus

Regenerative dynamics stem from the coordination of pathways shared with processes of reproduction, post-embryonic development and any tissue mechanisms triggered to reconstitute damaged or lost cells and tissues. In living organisms, following a wound, immune cells are recruited to the injured area to defend against pathogens and promote the structural and functional restoration of the damaged tissue. This repair process is thoroughly investigated in sea stars throughout their development, from the initial repair stages to the actual regenerative phase. In this context, circulating coelomocytes play a key role contributing to the onset and regulation of inflammation, both of which are essential prerequisites for downstream repair. In this work, we investigated the cellular and biochemical responses to the post-traumatic stress following arm amputation in the common sea star Echinaster sepositus . We focused on lysozyme-like activity, the production of reactive oxygen species (ROS), and the expression of the allograft inflammatory factor 1 ( aif-1 ) gene, which encodes a protein (AIF-1) produced by macrophages during inflammatory responses in vertebrates. This marker is highly conserved across invertebrates, including echinoderms, where AIF-1 is a recognized mediator of inflammatory responses. • The post-traumatic response of the E. sepositus coelomocytes was evaluated • Lysozyme-like activity, ROS production increased 24h post amputation. • AIF-1 increases in E. sepositus coelomocytes following experimental arm injury • The E. sepositus AIF-1 sequence confirms that it is a highly conserved gene • During the early post-traumatic period, the defence system remains efficient