Fish possess a highly diverse, strong innate immune system and were the first vertebrates to develop an adaptive immune system. Several fish vaccines against viral or bacterial diseases, most of which comprise inactivated pathogens, are now available. However, researchers are working intensively to enhance vaccine efficiency by developing new vaccines, containing adjuvants and immunostimulants, and new formulations based on encapsulation.
In a work recently published in Vaccine, researchers studied the biodistribution and immunological efficacy of immunostimulant-loaded nanoliposomes (called NLc liposomes) in zebrafish in vivo. The study was coordinated from the Universitat Autònoma de Barcelona (UAB) by the Evolutive Immunology Group at the Institut de Biotecnologia i de Biomedicina (IBB – UAB), led by the Ramon y Cajal Researcher Dr. Nerea Roher, and the Supramolecular NanoChemistry and Materials Group at the Institut Català de Nanociència i Nanotecnologia (ICN2), led by ICREA Research Professor Daniel Maspoch. The present work was supported by funds from Fundación Ramon Areces, MINECO, and Aposta (UAB).
Thanks to the adaptation of a non-invasive imaging method widely used in mammalian models, researchers tracked the nanoliposomes in adult zebrafish in vivo. The spleen was the main organ in which the liposomes had accumulated after intraperitoneal injection. This finding is consistent with the fact that the spleen is amongst the most important organs for filtering out foreign agents and is the main organ for antigen presentation in teleost fish.
To test whether the NLc liposomes could protect fish against bacterial infection, researchers developed a new infection model using Pseudomonas aeruginosa, an opportunistic pathogen in fish and in humans. The level of protection observed in the fish treated with NLc liposomes, regardless of the administration route, suggests the potential utility of these liposomes as a broad-spectrum tool for immunological protection of fish. Furthermore, the fact that the mixture of free immunostimulants did not offer protection in any of the infection models underscores the importance of encapsulating in liposomes to ensure optimal activation of the immune system.
The results obtained with NLc liposomes were promising. Additionally, these liposomes, once lyophilised, can be easily stored for long periods of time without losing their efficacy. Thus, the authors of the work are confident that this approach will ultimately prove fruitful for use in diverse therapeutic contexts.
Source: Institut Català de Nanociència i Nanotecnologia