Ultrasonography study of the skin wound healing process in gilthead seabream (Sparus aurata).

This work aimed to carry out an in vivo study of the skin healing process in gilthead seabream (Sparus aurata) after being experimentally wounded. Firstly, the structure of normal skin was studied by real-time ultrasonography (Vevo Lab, VisualSonics) and light microscopy. Besides this, experimental wounds were made on the left flank of each fish with a circular biopsy punch (8 mm diameter) below the lateral line. The healing process was assessed on live fish at 0, 6, 11 and 23 days post-wounding using the real-time ultrasonography in B-mode and Power Doppler mode (Vevo 3100 FUJIFILM, VisualSonics). Through the ultrasonography images, both the skin structure and the evolution of the changes that wounds originated in the surrounding tissues were studied in vivo over time. Concomitantly, the pattern of neovascularization in the wounded area was followed during the healing process and it was demonstrated that, although the neovascularization started very early after the skin damage, it was increased in wounded areas from day 11 post-wounding onwards. The results obtained proved the utility and power of using ultrasounds in fish to evaluate in vivo complex biological processes in real time, which are difficult to study by other methodologies. The present data shed some light on the reparation of external injuries in aquatic vertebrates.

Humoral immune parameters in serum of gilthead seabream (Sparus aurata L.) after induced skin injury.

Skin lesions contribute to significant rates of morbidity and mortality in fish because they permit the entry of pathogens. Different seric immune parameters (IgM level, protease, antiprotease, peroxidase and lysozyme) and bactericidal activity (against Vibrio harveyi and Photobacterium damsealae) of gilthead seabream (Sparus aurata L.) specimens were evaluated after experimentally wounding fish in two body locations (above or below the lateral line). The results demonstrate that the level of several immune parameters present in fish serum (IgM, proteases, peroxidase and bactericidal activity) showed statistically significant variations depending on the site of the skin wound and the time post-wounding (from 0 to 7 days). However, other parameters (such as antiproteases or lysozyme) remained unaltered during the experiment and did not differs from the values recorded on control fish (non-wounded). The highest activities recorded coincided with the inflammatory healing phase. Moreover, many more significant variations were observed in fish wounded below the lateral line than in those wounded above the lateral line. The present results demonstrate the importance of skin integrity in the maintenance of fish body homeostasis.

Healing and mucosal immunity in the skin of experimentally wounded gilthead seabream (Sparus aurata L).

Skin lesions are very common in fisheries, increasing the risk of pathogens entering through the wounded skin of the fish. In the present assay, the progression of wound healing was studied over a 7 day period in gilthead seabream (Sparus aurata L.) after making experimental wounds in two different locations: above (group A) or below (group B) the lateral line. Macroscopic observation confirmed faster wound healing of the wounds of fish from group B. Furthermore, several immune-related components were studied in the skin mucus of wounded fish to ascertain whether wounding altered the mucus composition compared with the values obtained from non-wounded fish (group C, control). Significant variations were detected depending on both the site of the wound and the studied parameter. At the same time, the gene expression profile of several immune-relevant genes, including pro-inflammatory (il1b,il6, tnfa), anti-inflamamtory (tgfb, il10), immunoglobulins (ighm, ight), involved in oxidative stress (sod, cat) and in skin regeneration (krt1and grhl1) were studied in the three groups of fish (A, B and C). The results throw further light on the complex process of skin wound healing in fish, since substantial changes in the skin mucus and in the skin gene expression originated by the presence of wounds were observed. This work underline some important differences depending on the place of the fish body where the wound is located. Of particular note was the fact that such changes depended on the site of the wound.