An investigation into the wound healing mechanism of different degrees of gill injuries in the Solenaia oleivora

In this study, we investigated the mechanism of gill wound healing in the Solenaia oleivora by simulating different degrees of gill injury models. Our study showed that the oxygen consumption rate, ammonia excretion rate, and feeding rate did not change significantly in the mild group at 2 and 12h post-injury, while the severe group was significantly lower than the control group at 2,12h post-injury, probably because the severe injury had threatened the respiratory metabolism of Solenaia oleivora mussels. As the repair of tissue damage required a large amount of energy consumption, the oxygen consumption rate, feeding rate and ammonia excretion rate of the mild group were significantly higher than those of the control group at 24h, 48 and 72h post-injury, while the feeding rate, ammonia excretion rate and oxygen consumption rate of the severe group were significantly higher than those of the control group at 72h post-injury. Analysis based on tissue sections and transcriptome results showed that at 2 and 12 h post-injury in the mildly ill group, blood cells migrated toward the wound and plugged the wound to promote the inflammatory response of the wound, which might be related to the upregulation of TNF signaling as well as genes related to immunity; and the upregulation of genes related to the actin cytoskeleton might be related to the wound contraction and phagocytosis of blood cells. At 24 hours post-injury, genes and pathways associated with antioxidant enzymes, chaperonins, autophagy, lysosomes, biochemical pathways, and energy metabolism were activated to promote the transition of the wound from an inflammatory response to an epithelialization process. At 48 hours post-injury, Toll and Imd signaling are down-regulated, and extracellular matrix receptors and genes related to extracellular matrix (collagen, integrins, glycoproteins) are activated to promote the epithelialization process of the wound. At 72 hours after injury, upregulation of proline and arginine metabolism and mitochondrial gene expression continued to promote the epithelialization process. In the severe injury group, many amino acid metabolisms were suppressed and primary immunodeficiencies were activated at 2 and 12 h post-injury Heavy injury may cause disturbances in Solenaia oleivora metabolism and immunity. However, the organism does something to fill this gap. At 2, 12, 24, and 48 h post-injury, genes related to the actin cytoskeleton, lipid and metabolism, glycolysis, glycosyltransferases, chaperonins, guanylate-binding proteins, and NOD-like receptors are activated to promote wound contraction and inflammatory responses. At 72 hours after injury, interleukin-4 and thymosin B-4 were activated, and the NF-kappa B signaling pathway was inhibited to promote anti-inflammatory responses in wounds; epithelialization of the wounds was observed at this point in time in tissue sections, and the activation of ribosomal proteins, ATP, EGF may have facilitated the process of epithelialization. This study provides new insights into the mechanism of gill wound healing in the Solenaia oleivora.