title: Which Th pathway is involved during late stage amoebic gill disease?
abstract: Amoebic gill disease (AGD) is an emerging disease in North European Atlantic salmon (Salmo salar Linnaeus 1758) aquaculture caused by the amoeba Paramoeba perurans. The host immune response to AGD infection is still not well understood despite past attempts to investigate host-pathogen interactions. With the significant increase in our knowledge of cytokine genes potentially involved in Th responses in recent years, we examined their involvement in this disease using Atlantic salmon post-smolts sampled 3 weeks after exposure to either 500 or 5000 cells/l P. perurans. Gene expression analysis of cytokines potentially involved in the different Th pathways was performed on the first gill arch including the interbranchial lymphoid tissue (ILT). Th1, Th17 and Treg pathways were found to be significantly down regulated, mainly in samples from fish given the higher dose. In contrast, the Th2 pathway was found to be significantly up regulated by both infection doses. Correlation analysis of the gene expression data and the P. perurans load, assessed by real time RT-PCR of the 18S rRNA, was also performed. In humans, Th2 driven responses are characterized by the production of IgE, which in the majority of worm infections results in the generation of a Th2-mediated response and directs the immune system away from a Th1 inflammatory response. The present results seen during late stage AGD suggest that either an immune evasion strategy, similar to the responses driven by helminthic parasites to avoid cell-mediated killing mechanisms, or an allergic reaction caused by the parasite, is occurring.
authors.affiliation: Scottish Fish Immunology Research Centre, Institute of Biological and Environmental Sciences, University of Aberdeen, Tillydrone Avenue, Aberdeen AB24 2TZ, UK; Marine Scotland Science Marine Laboratory, 375 Victoria Rd, Aberdeen AB11 9DB, UK. Electronic address: r01ob13@abdn.ac.uk.
authors.forename: Ottavia
authors.initials: O
authors.lastname: Benedicenti
authors.affiliation: Marine Scotland Science Marine Laboratory, 375 Victoria Rd, Aberdeen AB11 9DB, UK.
authors.forename: Catherine
authors.initials: C
authors.lastname: Collins
authors.affiliation: Scottish Fish Immunology Research Centre, Institute of Biological and Environmental Sciences, University of Aberdeen, Tillydrone Avenue, Aberdeen AB24 2TZ, UK.
authors.forename: Tiehui
authors.initials: T
authors.lastname: Wang
authors.affiliation: Marine Scotland Science Marine Laboratory, 375 Victoria Rd, Aberdeen AB11 9DB, UK.
authors.forename: Una
authors.initials: U
authors.lastname: McCarthy
authors.affiliation: Scottish Fish Immunology Research Centre, Institute of Biological and Environmental Sciences, University of Aberdeen, Tillydrone Avenue, Aberdeen AB24 2TZ, UK. Electronic address: c.secombes@abdn.ac.uk.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Secombes
mesh_terms: D000562:Amebiasis / Q000235:genetics / Q000276:immunology* / Q000469:parasitology / Q000662:veterinary; D056894:Amoebozoa / Q000502:physiology; D000818:Animals; D016207:Cytokines / Q000235:genetics; D005393:Fish Diseases / Q000235:genetics / Q000276:immunology* / Q000469:parasitology; D020869:Gene Expression Profiling; D005880:Gills / Q000276:immunology* / Q000473:pathology; D008221:Lymphoid Tissue / Q000276:immunology; D059208:Parasite Load; D020317:Salmo salar / Q000235:genetics / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D016207:Cytokines
keywords: Amoebic gill disease; Atlantic salmon; Cytokines; Interbranchial lymphoid tissue; Th pathways