Characterization of BAFF and APRIL subfamily receptors in rainbow trout (Oncorhynchus mykiss). Potential role of the BAFF/APRIL axis in the pathogenesis of proliferative kidney disease

We would like to thank Lucia González for technical assistance and Rosario Castro for producing some of the cDNAs used in this study. This work was supported by the European Research Council (ERC Starting Grant 2011 280469) and by the European Commission under the 7th Framework Programme for Research and Technological Development (FP7) of the European Union (Grant Agreement 311993 TARGETFISH) and under the Horizon H2020 research and innovation programme (Grant H2020-634429 ParaFishControl). This work was also partially funded by project AGL2014-54456-JIN from the Spanish Ministry of Economy and Competitiveness (MINECO). JWH was supported by the Swiss National Science Foundation (grant reference CRSII3_147649-1).Peer reviewedPublisher PD

Evaluation of immunomodulatory effects of lactic acid bacteria in turbot (Scophthalmus maximus)

7 pages, 4 figures.In the present work, the effects of several lactic acid bacteria on the immune response of turbot (Scophthalmus maximus) macrophages have been studied both in vitro and in vivo. Out of six lactic acid bacterial strains tested, only heat-killed Lactococcus lactis significantly increased the turbot head kidney macrophage chemiluminescent (CL) response after 24 h of incubation. Nitric oxide (NO) was also significantly enhanced by this bacterium after 72 h of incubation with either viable (103 and 106 cells/ml) or heat-killed (106 cells/ml) bacteria. Viable Leuconostoc mesenteroides (106 cells/ml) was also capable of significantly increasing NO production. Since L. lactis proved to be the strain with more effects on the host immune function, further in vivo and in vitro experiments were conducted with this bacterium. The in vitro capacity of L. lactis to adhere to turbot intestinal mucus was positively confirmed. When orally administered, L. lactis significantly increased the macrophage CL response and the serum NO concentration after 7 days of daily administration. The antibacterial effect of the extracellular products from the six LAB strains against the fish-pathogenic bacterium Vibrio anguillarum was also demonstrated in vitro.This work was partially supported by the project 1FD97-0044-C03-03 from FEDER funds and a grant from Caixa Galicia (Spain). L. Villamil acknowledges the University of Vigo for a research fellowship. C. Tafalla acknowledges the Consejo Superior de Investigaciones Científicas (CSIC) for a research fellowship.Peer reviewe

Teleost Chemokines and Their Receptors

Chemokines are a superfamily of cytokines that appeared about 650 million years ago, at the emergence of vertebrates, and are responsible for regulating cell migration under both inflammatory and physiological conditions. The first teleost chemokine gene was reported in rainbow trout in 1998. Since then, numerous chemokine genes have been identified in diverse fish species evidencing the great differences that exist among fish and mammalian chemokines, and within the different fish species, as a consequence of extensive intrachromosomal gene duplications and different infectious experiences. Subsequently, it has only been possible to establish clear homologies with mammalian chemokines in the case of some chemokines with well-conserved homeostatic roles, whereas the functionality of other chemokine genes will have to be independently addressed in each species. Despite this, functional studies have only been undertaken for a few of these chemokine genes. In this review, we describe the current state of knowledge of chemokine biology in teleost fish. We have mainly focused on those species for which more research efforts have been made in this subject, specially zebrafish (Danio rerio), rainbow trout (Oncorhynchus mykiss) and catfish (Ictalurus punctatus), outlining which genes have been identified thus far, highlighting the most important aspects of their expression regulation and addressing any known aspects of their biological role in immunity. Finally, we summarise what is known about the chemokine receptors in teleosts and provide some analysis using recently available data to help characterise them more clearly

Distinct modes of action of CD40L and adaptive cytokines IL-2, IL-4/13, IL-10 and IL-21 on rainbow trout IgM+ B cells

Acknowledgements This work was supported by the European Research Council (ERC Consolidator Grant 725061) and by the Spanish Ministry of Science, Innovation and Universities (project AGL2017-85494-C2-1-R).Peer reviewedPublisher PD

Rainbow trout CK9, a CCL25-like ancient chemokine that attracts and regulates B cells and macrophages, the main antigen presenting cells in fish

ACKNOWLEDGMENTS The authors want to thank Dr. Oriol Sunyer for the anti-IgT and Dr. Uwe Fischer for the anti-CD8 antibodies used in this study. We also want to acknowledge Lucía González Torres for technical assistance. GRANT SUPPORT This work was supported by the European Research Council (ERC Starting Grant 2011 280469), by the European Commission under the 7th Framework Programme for Research and Technological Development (FP7) of the European Union (Grant Agreement 311993 TARGETFISH) and by project AGL2011-29676 from the Spanish Ministry of Economy and Competitiveness (MINECO). C. Aquilino was supported by a MINECO PhD student fellowshipPeer reviewedPublisher PD

It's a hard knock life for some: Heterogeneity in infection life history of salmonids influences parasite disease outcomes.

Heterogeneity in immunity occurs across numerous disease systems with individuals from the same population having diverse disease outcomes. Proliferative kidney disease (PKD) caused by Tetracapsuloides bryosalmonae, is a persistent parasitic disease negatively impacting both wild and farmed salmonids. Little is known of how PKD is spread or maintained within wild susceptible populations. We investigated an aspect of fish disease that has been largely overlooked, that is, the role of the host phenotypic heterogeneity in disease outcome. We examined how host susceptibility to T. bryosalmonae infection, and the disease PKD, varied across different infection life-history stages and how it differs between naïve, re-infected and persistently infected hosts. We investigated the response to parasite exposure in host phenotypes with (a) different ages and (b) heterogeneous infection life histories. Among (a) the age phenotypes were young-of-the-year (YOY) fish and juvenile 1+ fish (fish older than one) and, for (b) juvenile 1+ infection survivors were either re-exposed or not re- exposed to the parasite and response phenotypes were assigned post-hoc dependant on infection status. In fish not re-exposed this included fish that cleared infection (CI) or had a persistent infection (PI). In fish re-exposed these included fish that were re-infected (RI), or re-exposed and uninfected (RCI). We assessed both parasite-centric (infection prevalence, parasite burden, malacospore transmission) and host-centric parameters (growth rates, disease severity, infection tolerance and the immune response). In (a), YOY fish, parasite success and disease severity were greater and differences in the immune response occurred, demonstrating an ontogenetic decline of susceptibility in older fish. In (b), in PI and RI fish, parasite success and disease severity were comparable. However, expression of several adaptive immunity markers was greater in RI fish, indicating concomitant immunity, as re-exposure did not intensify infection. We demonstrate the relevance of heterogeneity in infection life history on disease outcome and describe several distinctive features of immune ontogeny and protective immunity in this model not previously reported. The relevance of such themes on a population level requires greater research in many aquatic disease systems to generate clearer framework for understanding the spread and maintenance of aquatic pathogens

Type I interferon regulates the survival and functionality of B cells in rainbow trout

This work was supported by the European Research Council (ERC Consolidator Grant No. 2016 725061 TEMUBLYM), by the Spanish Ministry of Science, Innovation and Universities (project AGL2017-85494-C2-1-R) and by the Comunidad de Madrid (Grant No. 2016-T1/BIO-1672).Peer reviewedPublisher PD