Toll-like receptors in maraena whitefish: Evolutionary relationship among salmonid fishes and patterns of response to Aeromonas salmonicida. (July 2016)

• Record Type: Journal Article
• Authors: Altmann, Simone; Korytář, Tomáš; Kaczmarzyk, Danuta; Nipkow, Mareen; Kühn, Carsten; Goldammer, Tom; Rebl, Alexander
• Is Part Of: Fish & shellfish immunology. Volume 54(2016:Jul.)
• Page Start: 391
• Page End: 401
• Publication Date: 2016-07
• Subjects: Aeromonas salmonicida -- Large granular lymphocytes -- Maraena whitefish -- Pathogen-associated molecular patterns -- Salmonidae -- Teleost; cDNA complementary DNA -- DAMP danger-associated molecular pattern -- FC fold change -- LRR leucine-rich repeats -- IL interleukin -- PAMP pathogen-associated molecular pattern -- PBL peripheral blood leukocytes -- PBS phosphate-buffered saline -- RT-qPCR quantitative real-time reverse transcription polymerase chain reaction -- TIR Toll/interleukin-1 receptor homology domain -- TLR toll-like receptor -- TMD transmembrane domain -- TNF tumour necrosis factor (alpha); Fishes -- Immunology -- Periodicals; Shellfish -- Immunology -- Periodicals; Poissons -- Immunologie -- Périodiques; Crustacés -- Immunologie -- Périodiques; 571.9617
• DOI: 10.1016/j.fsi.2016.04.125
• Languages: English
• ISSNs: 1050-4648

Abstract

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. Highlights: 14 TLRs from Coregonus maraena were isolated and characterized. Fish-specific TLRs are highly expressed across selected tissues in healthy whitefish. A . salmonicida induced marked trafficking granulated cells in whitefish. Granulated cell number increased in blood together with the expression of cytokines. Concomitantly, TLR transcript abundance was only moderately increased.