title: Toll-like receptors in maraena whitefish: Evolutionary relationship among salmonid fishes and patterns of response to Aeromonas salmonicida.
abstract: Toll-like receptors (TLRs) interact directly with particular pathogenic structures and are thus highly important to innate immunity. The present manuscript characterises a suite of 14 TLRs in maraena whitefish (Coregonus maraena), a salmonid species with increasing importance for aquaculture. Whitefish TLRs were structurally and evolutionary analysed. The results revealed a close relationship with TLRs from salmonid fish species rainbow trout and Atlantic salmon. Profiling the baseline expression of TLR genes in whitefish indicated that mainly members of the TLR11 family were highly expressed across all investigated tissues. A stimulation model with inactivated Aeromonas salmonicida was used to induce inflammation in the peritoneal cavity of whitefish. This bacterial challenge induced the expression of pro-inflammatory cytokine genes and evoked a strong influx of granulated cells of myeloid origin into the peritoneal cavity. As a likely consequence, the abundance of TLR-encoding transcripts increased moderately in peritoneal cells, with the highest levels of transcripts encoding non-mammalian TLR22a and a soluble TLR5 variant. In the course of inflammation, the proportion of granulated cells increased in peripheral blood accompanied by elevated TLR copy numbers in spleen and simultaneously reduced TLR copy numbers in head kidney at day 3 post-stimulation. Altogether, the present study provides in-vivo evidence for relatively modest TLR response patterns, but marked trafficking of myeloid cells as an immunophysiological consequence of A. salmonicida inflammation in whitefish. The present results contribute to improved understanding of the host-pathogen interaction in salmonid fish.
authors.affiliation: Leibniz Institute for Farm Animal Biology (FBN), Institute for Genome Biology, Fish Genetics Unit, Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany.
authors.forename: Simone
authors.initials: S
authors.lastname: Altmann
authors.affiliation: Friedrich-Loeffler-Institut (FLI), Federal Research Institute for Animal Health, Institute of Immunology, Laboratory for Comparative Immunology, Südufer 10, 17493 Greifswald, Insel Riems, Germany; Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce Street, Philadelphia, PA 19104, USA.
authors.forename: Tomáš
authors.initials: T
authors.lastname: Korytář
authors.affiliation: Leibniz Institute for Farm Animal Biology (FBN), Institute for Genome Biology, Fish Genetics Unit, Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany; School of Biotechnology, KTH-Royal Institute of Technology, Department of Proteomics, Roslagstullsbacken 21, 10450 Stockholm, Sweden.
authors.forename: Danuta
authors.initials: D
authors.lastname: Kaczmarzyk
authors.affiliation: Leibniz Institute for Farm Animal Biology (FBN), Institute for Genome Biology, Fish Genetics Unit, Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany.
authors.forename: Mareen
authors.initials: M
authors.lastname: Nipkow
authors.affiliation: State Research Centre for Agriculture and Fishery (LFA M-V), Institute for Fishery, Fischerweg 408, Rostock, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Kühn
authors.affiliation: Leibniz Institute for Farm Animal Biology (FBN), Institute for Genome Biology, Fish Genetics Unit, Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany.
authors.forename: Tom
authors.initials: T
authors.lastname: Goldammer
authors.affiliation: Leibniz Institute for Farm Animal Biology (FBN), Institute for Genome Biology, Fish Genetics Unit, Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany. Electronic address: rebl@fbn-dummerstorf.de.
authors.forename: Alexander
authors.initials: A
authors.lastname: Rebl
mesh_terms: D048409:Aeromonas salmonicida / Q000502:physiology; D000818:Animals; D019143:Evolution, Molecular; D029941:Fish Proteins / Q000235:genetics* / Q000378:metabolism; D005667:Furunculosis / Q000235:genetics* / Q000276:immunology / Q000382:microbiology; D016905:Gram-Negative Bacterial Infections / Q000235:genetics / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D007113:Immunity, Innate / Q000235:genetics; D010802:Phylogeny; D012487:Salmonidae / Q000145:classification; D051193:Toll-Like Receptors / Q000235:genetics* / Q000378:metabolism
chemical_list: D029941:Fish Proteins; D051193:Toll-Like Receptors
keywords: Aeromonas salmonicida; Large granular lymphocytes; Maraena whitefish; Pathogen-associated molecular patterns; Salmonidae; Teleost