The fish coagulation system could help to prevent infection by the ciliate parasite Philasterides dicentrarchi

• Main Authors: Blanco-Abad, V., Noia, M., Valle, A., Fontenla, F., Folgueira, I., Felipe, A. P. de, Pereiro, Patricia, Leiro, J., Lamas, J.
• Other Authors: European Commission
• Format: Conference Object
• Language: English
• Published: 2019
• Subjects: Las Palmas; Turbot
• Online Access: http://hdl.handle.net/10261/203737; https://doi.org/10.13039/501100000780

3rd International Symposium on Fish & Shellfish Immunology, June 16th-20th 2019, Las Palmas de Gran Canaria (Spain) n addition to its role in hemostasis, the coagulation system is involved in defence against pathogens in invertebrates and vertebrates. In mammals, the coagulation system has been shown to participate in entrapping pathogens and activating the early immune response. Although many studies have described different components of the fish coagulation system, there is a lack of information about the importance of the system in host defence against pathogens. In the present study, we showed that injecting turbot (Scophthalamus maximus) with the pathogenic ciliate Philasterides dicentrarchi generates the formation of macroscopic intraperitoneal clots in the fish. The clots contained abundant, immobilized ciliates, many of which were lysed. We observed that the plasma clots immobilize and kill the ciliates in vitro. However, fish plasma treated with a tetrapeptide known to inhibit brinogen/thrombin clotting in mammals killed P. dicentrarchi slightly faster than the untreated plasma, although the overall mortality rate was similar. We also found that kaolin, a particulate activator of the intrinsic pathway in mammals, accelerates plasma clotting in turbot. PMA-stimulated neutrophils, living ciliates and several ciliate components (such as cilia, proteases and DNA) also displayed procoagulant activity in vitro. In addition to generating clots in the peritoneal cavity, i.p. injection of ciliates generated massive migration of neutrophils to the peritoneal cavity, with the formation of large cell aggregates and of numerous fibrin-like fibres in the peritoneal exudate, many of which were associated with peritoneal leukocytes and ciliates. Expression of the CD18/CD11b gene, an integrin associated with cell adhesion and the induction of fibrin formation, was upregulated in the peritoneal leukocytes. In conclusion, the results of the present study suggest that the fish coagulation system plays an important role in ...