Antimicrobial Peptides (AMP) are vital elements of the host’s innate immunity due to their microbicidal and immunomodulatory properties. AMPs can be a promising solution for sustainable aquaculture development in preventing or treating infectious diseases. Specifically, anisaxins, cecropin-like helminthic AMPs from the zoonotic marine nematodes, Anisakis simplex and Anisakis pegreffii, express high potency against clinical and referent human bacterial Gram-negative isolates.
The immunomodulatory properties of annisaxin-2S (A-2S) were firstly tested in vitro in the common carp ( Cyprinus carpio ) red blood cells (RBC) and white blood cells (WBC) exposed to fish pathogen, the myxozoan parasite Spaherospora molnari , over three time-points (0, 1 and 24h). Secondly, the carp was challenged in vivo with the parasite and/ or immunosuppressed by cortisol. Blood was collected before the challenge and 2, 3 and 4 weeks after challenge, and isolated RBC and WBC were exposed to A-2S. Expression of target cytokines (il1β , il6 , il10 , tnf𝛼 and inf𝛾 ) in RBC and WBC from both assays was measured by qPCR, and flow cytometry was used to determine the kinetics of reactive oxygen species production over time in the in vivo experiment.
The results revealed that all pro-inflammatory cytokines, especially il1β , tnfα , and infγ, have shown statistically significant expressions in A-2S-stimulated RBC and WBC. ROS production and cell proliferation also increased significantly in both A-2S-stimulated cell lineages, progressing from weeks 2 to 4 (parasitemia). Anisaxin-2S demonstrates notable immunomodulatory properties in the blood cells of healthy fish. Initially, it boosts a pro-inflammatory reaction, which later is balanced by an anti-inflammatory response. In contrast, in the presence of a co-antigen, i.e ., fish infected with the parasite S. molnari , the environment becomes anti-inflammatory at an early stage. Overall, the expression of targets of the innate immunity increases towards 24h or over four weeks, in the case of the in vivo (Fig.1) and in vitro challenge assay with S. molnari . The pathway activating the cytokines production, however, still needs to be elucidated. Although immunomodulatory properties have been so far mainly attributed to the flatworms’ AMPs, the nematode A-2S has indicated a considerable activation of innate cells. This could be valuable for designing aquaculture nutraceuticals and using anisaxins as an alternative against the treatment of infectious diseases.
Antimicrobial Peptides (AMP) are vital elements of the host’s innate immunity due to their microbicidal and immunomodulatory properties . AMPs can be a promising solution for sustainable aquaculture development in preventing or treating infectious diseases. Specifically, anisaxins, cecropin-like helminthic AMPs from the zoonotic marine nematodes, Anisakis simplex and Anisakis pegreffii , express high potency against clinical and referent human bacterial Gram-negative isolates.
Funding : Funded by the European Union under the Horizon Europe Programme, Grant Agreement No. 101084204 (Cure4Aqua). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Executive Agency (REA). Neither the European Union nor the granting authority can be held responsible for them.