1
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Etayo A, Bjørgen H, Hordvik I, Øvergård AC. Possible transport routes of IgM to the gut of teleost fish. Fish Shellfish Immunol 2024; 149:109583. [PMID: 38657879 DOI: 10.1016/j.fsi.2024.109583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 04/12/2024] [Accepted: 04/22/2024] [Indexed: 04/26/2024]
Abstract
Fish rely on mucosal surfaces as their first defence barrier against pathogens. Maintaining mucosal homeostasis is therefore crucial for their overall well-being, and it is likely that secreted immunoglobulins (sIg) play a pivotal role in sustaining this balance. In mammals, the poly-Ig receptor (pIgR) is an essential component responsible for transporting polymeric Igs across mucosal epithelia. In teleost fish, a counterpart of pIgR has been identified and characterized, exhibiting structural differences and broader mRNA expression patterns compared to mammals. Despite supporting evidence for the binding of Igs to recombinant pIgR proteins, the absence of a joining chain (J-chain) in teleosts challenges the conventional understanding of Ig transport mechanisms. The transport of IgM to the intestine via the hepatobiliary route is observed in vertebrates and has been proposed in a few teleosts. Investigations on the stomachless fish, ballan wrasse, revealed a significant role of the hepatobiliary route and interesting possibilities for alternative IgM transport routes that might include pancreatic tissue. These findings highlight the importance of gaining a thorough understanding of the mechanisms behind Ig transport to the gut in various teleosts. This review aims to gather existing information on pIgR-mediated transport across epithelial cells and immunoglobulin transport pathways to the gut lumen in teleost fish. It provides comparative insights into the hepatobiliary transport of Igs to the gut, emphasizing the current understanding in teleost fish while exploring potential alternative pathways for Ig transport to the gut lumen. Despite significant progress in understanding various aspects, there is still much to uncover, especially concerning the diversity of mechanisms across different teleost species.
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Affiliation(s)
- Angela Etayo
- Institute of Marine Research, Bergen, Norway; Fish Health group, Department of Biological sciences, University of Bergen, Norway.
| | - Håvard Bjørgen
- Anatomy Unit, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Ivar Hordvik
- Fish Health group, Department of Biological sciences, University of Bergen, Norway
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2
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Bjørgen H, Koppang EO. The melano-macrophage: The black leukocyte of fish immunity. Fish & Shellfish Immunology 2024; 148:109523. [PMID: 38522495 DOI: 10.1016/j.fsi.2024.109523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Revised: 03/20/2024] [Accepted: 03/21/2024] [Indexed: 03/26/2024]
Abstract
Melanin and the process of melanin synthesis or melanogenesis have central roles in the immune system of insects, and production of melanin-synthesizing enzymes from their haemocytes may be induced following activation through danger signals. Melanin-containing macrophage-like cells have been extensively studied in amphibians and they are also present in reptiles. In fish, melano-macrophages are especially recognized with respect to melano-macrophage centres (MMCs), hypothesized to be analogues of germinal centres in secondary lymphoid organs of mammals and some birds. Melano-macrophages are in addition present in several inflammatory conditions, in particular melanised focal changes, or black spots, in the musculature of farmed Atlantic salmon, Salmo salar. Melanins are complex compounds that may be divided into different forms which all have the ability to absorb and scatter light. Other functions include the quenching of free radicals and a direct effect on the immune system. According to the common view held in the pigment cell community, vertebrate melanin synthesis with melanosome formation may only occur in cells of ectodermal origin. However, abundant information suggests that also myeloid cells of ectothermic vertebrates may be classified as melanocytes. Here, we discuss these opposing views and review relevant literature. Finally, we review the current status on the research concerning melanised focal muscle changes that represent the most severe quality problem in Norwegian salmon production, but also other diseases where melano-macrophages play important roles.
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Affiliation(s)
- Håvard Bjørgen
- Unit of Anatomy, Veterinary Faculty, Norwegian University of Life Sciences (NMBU), Ås, Norway
| | - Erling Olaf Koppang
- Unit of Anatomy, Veterinary Faculty, Norwegian University of Life Sciences (NMBU), Ås, Norway.
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3
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Sun B, Vindas MA, Kavaliauskiene S, Bjørgen H, Koppang EO, Wisløff H, Frisk M, Lund H, Johansen IB. Persistent immune responses in the heart determine the outcome of cardiomyopathy syndrome in Atlantic salmon (Salmo salar). Fish Shellfish Immunol 2024; 147:109404. [PMID: 38325590 DOI: 10.1016/j.fsi.2024.109404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 01/18/2024] [Accepted: 01/23/2024] [Indexed: 02/09/2024]
Abstract
Cardiomyopathy syndrome (CMS) caused by piscine myocarditis virus (PMCV) is a severe cardiac disease in Atlantic salmon (Salmo salar) and one of the leading causes of morbidity and mortality in the Norwegian aquaculture industry. Previous research suggest a variation in individual susceptibility to develop severe disease, however the role of the immune response in determining individual outcome of CMS is poorly understood particularly in cases where fish are also challenged by stress. The present study's aim was therefore to characterize cardiac transcriptional responses to PMCV infection in Atlantic salmon responding to infection under stressful conditions with a high versus low degree of histopathological damage. The study was performed as a large-scale controlled experiment of Atlantic salmon smolts from pre-challenge to 12 weeks post infection (wpi) with PMCV, during which fish were exposed to intermittent stressors. RNA sequencing (RNAseq) was used to compare the heart transcriptome of high responders (HR) with atrium histopathology score '4' and low responders (LR) with score '0.5' at 12 wpi. A high-throughput quantitative PCR (qPCR) analysis was used to compare immune gene transcription between individuals sampled at 6, 9 and 12 wpi. Based on RNAseq and qPCR results, RNAscope in situ hybridization (ISH) was performed for visualization of IFN-γ - and IFNb producing immune cells in affected heart tissue. Compared to LR, the transcription of 1592 genes was increased in HR at 12 wpi. Of these genes, around. 40 % were immune-related, including various chemokines, key antiviral response molecules, and genes. associated with a Th1 pro-inflammatory immune response. Further, the qPCR analysis confirmed. increased immune gene transcription in HR at both 9 and 12 wpi, despite a decrease in PMCV. transcription between these time points. Interestingly, increased IFNb transcription in HR suggests the. presence of high-quantity IFN secreting cells in the hearts of these individuals. Indeed, RNAscope. confirmed the presence of IFN-γ and IFNb-positive cells in the heart ventricle of HR but not LR. To conclude, our data indicate that in severe outcomes of PMCV infection various chemokines attract leucocytes to the salmon heart, including IFN-γ and IFNb-secreting cells, and that these cells play important roles in maintaining persistent antiviral responses and a sustained host immunopathology despite decreasing heart viral transcription.
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Affiliation(s)
- Baojian Sun
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Marco A Vindas
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | | | - Håvard Bjørgen
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Erling Olaf Koppang
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | | | - Michael Frisk
- Institute for Experimental Medical Research, University of Oslo, Oslo, Norway
| | - Hege Lund
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Ida B Johansen
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway.
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4
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Kortner TM, Afanasyev S, Koppang EO, Bjørgen H, Krogdahl Å, Krasnov A. A comprehensive transcriptional body map of Atlantic salmon unveils the vital role of the intestine in the immune system and highlights functional specialization within its compartments. Fish Shellfish Immunol 2024; 146:109422. [PMID: 38307300 DOI: 10.1016/j.fsi.2024.109422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 01/25/2024] [Accepted: 01/31/2024] [Indexed: 02/04/2024]
Abstract
The intestine is a barrier organ that plays an important role in the immune system of Atlantic salmon. The immune functions are distributed among the diffuse gut lymphoid tissue containing diverse immune cells, and other cell types. Comparison of intestinal transcriptomes with those of other organs and tissues offers an opportunity to elucidate the specific roles of the intestine and its relationship with other parts of the body. In this work, a meta-analysis was performed on a large volume of data obtained using a genome-wide DNA oligonucleotide microarray. The intestine ranks third by the expression level of immune genes after the spleen and head kidney. The activity of antigen presentation and innate antiviral immunity is higher in the intestine than in any other tissue. By comparing transcriptome profiles, intestine shows the greatest similarity with the gill, head kidney, spleen, epidermis, and olfactory rosette (descending order), which emphasizes the integrity of the peripheral mucosal system and its strong connections with the major lymphoid organs. T cells-specific genes dominate among the genes co-expressed in these tissues. The transcription signature of CD8+ (86 genes, r > 0.9) includes a master gene of immune tolerance foxp3 and other negative regulators. Different segments of the intestine were compared in a separate experiment, in which expression gradients along the intestine were found across several functional groups of genes. The expression of luminal and intracellular (lysosome) proteases is markedly higher in pyloric caeca and distal intestine respectively. Steroid metabolism and cytochromes P450 are highly expressed in pyloric caeca and mid intestine while the distal intestine harbors genes related to vitamin and iron metabolism. The expression of genes for antigen presenting proteins and immunoglobulins shows a gradual increase towards the distal intestine.
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Affiliation(s)
- Trond M Kortner
- Norwegian University of Life Sciences, Faculty of Veterinary Medicine, Ås, Norway.
| | - Sergey Afanasyev
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Saint Petersburg, Russia
| | - Erling Olaf Koppang
- Norwegian University of Life Sciences, Faculty of Veterinary Medicine, Ås, Norway
| | - Håvard Bjørgen
- Norwegian University of Life Sciences, Faculty of Veterinary Medicine, Ås, Norway
| | - Åshild Krogdahl
- Norwegian University of Life Sciences, Faculty of Veterinary Medicine, Ås, Norway
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5
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Sun J, Ruiz Daniels R, Balic A, Andresen AMS, Bjørgen H, Dobie R, Henderson NC, Koppang EO, Martin SAM, Fosse JH, Taylor RS, Macqueen DJ. Cell atlas of the Atlantic salmon spleen reveals immune cell heterogeneity and cell-specific responses to bacterial infection. Fish Shellfish Immunol 2024; 145:109358. [PMID: 38176627 DOI: 10.1016/j.fsi.2024.109358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 12/23/2023] [Accepted: 01/02/2024] [Indexed: 01/06/2024]
Abstract
The spleen is a conserved secondary lymphoid organ that emerged in parallel to adaptive immunity in early jawed vertebrates. Recent studies have applied single cell transcriptomics to reveal the cellular composition of spleen in several species, cataloguing diverse immune cell types and subpopulations. In this study, 51,119 spleen nuclei transcriptomes were comprehensively investigated in the commercially important teleost Atlantic salmon (Salmo salar L.), contrasting control animals with those challenged with the bacterial pathogen Aeromonas salmonicida. We identified clusters of nuclei representing the expected major cell types, namely T cells, B cells, natural killer-like cells, granulocytes, mononuclear phagocytes, endothelial cells, mesenchymal cells, erythrocytes and thrombocytes. We discovered heterogeneity within several immune lineages, providing evidence for resident macrophages and melanomacrophages, infiltrating monocytes, several candidate dendritic cell subpopulations, and B cells at distinct stages of differentiation, including plasma cells and an igt + subset. We provide evidence for twelve candidate T cell subsets, including cd4+ T helper and regulatory T cells, one cd8+ subset, three γδT subsets, and populations double negative for cd4 and cd8. The number of genes showing differential expression during the early stages of Aeromonas infection was highly variable across immune cell types, with the largest changes observed in macrophages and infiltrating monocytes, followed by resting mature B cells. Our analysis provides evidence for a local inflammatory response to infection alongside B cell maturation in the spleen, and upregulation of ccr9 genes in igt + B cells, T helper and cd8+ cells, and monocytes, consistent with the recruitment of immune cell populations to the gut to deal with Aeromonas infection. Overall, this study provides a new cell-resolved perspective of the immune actions of Atlantic salmon spleen, highlighting extensive heterogeneity hidden to bulk transcriptomics. We further provide a large catalogue of cell-specific marker genes that can be leveraged to further explore the function and structural organization of the salmonid immune system.
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Affiliation(s)
- Jianxuan Sun
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Midlothian, UK
| | - Rose Ruiz Daniels
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Midlothian, UK
| | - Adam Balic
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Midlothian, UK; Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia
| | | | - Håvard Bjørgen
- Unit of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Ross Dobie
- Centre for Inflammation Research, The Queen's Medical Research Institute, Edinburgh BioQuarter, University of Edinburgh, Edinburgh, UK
| | - Neil C Henderson
- Centre for Inflammation Research, The Queen's Medical Research Institute, Edinburgh BioQuarter, University of Edinburgh, Edinburgh, UK; MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, UK
| | - Erling Olaf Koppang
- Unit of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Samuel A M Martin
- Scottish Fish Immunology Research Centre, School of Biological Sciences, University of Aberdeen, Aberdeen, UK
| | | | - Richard S Taylor
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Midlothian, UK
| | - Daniel J Macqueen
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Midlothian, UK.
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6
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Bjørgen H, Malik S, Rimstad E, Vaadal M, Nyman IB, Koppang EO, Tengs T. Correction to: Cellular heterogeneity in red and melanized focal muscle changes in farmed Atlantic salmon (Salmo salar) visualized by spatial transcriptomics. Cell Tissue Res 2024; 395:221. [PMID: 38158442 PMCID: PMC10837211 DOI: 10.1007/s00441-023-03856-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Affiliation(s)
- H Bjørgen
- Unit of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 1433, Ås, Norway
| | - S Malik
- Department of Breeding and Genetics, 1433, Nofima, Norway
| | - E Rimstad
- Unit of Virology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 1433, Ås, Norway
| | - M Vaadal
- Department of Breeding and Genetics, 1433, Nofima, Norway
| | - I B Nyman
- Unit of Virology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 1433, Ås, Norway
| | - E O Koppang
- Unit of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 1433, Ås, Norway
| | - T Tengs
- Department of Breeding and Genetics, 1433, Nofima, Norway.
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7
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Bjørgen H, Malik S, Rimstad E, Vaadal M, Nyman IB, Koppang EO, Tengs T. Cellular heterogeneity in red and melanized focal muscle changes in farmed Atlantic salmon (Salmo salar) visualized by spatial transcriptomics. Cell Tissue Res 2024; 395:199-210. [PMID: 38087072 PMCID: PMC10837230 DOI: 10.1007/s00441-023-03850-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 11/24/2023] [Indexed: 12/31/2023]
Abstract
Spatial transcriptomics is a technique that provides insight into gene expression profiles in tissue sections while retaining structural information. We have employed this method to study the pathological conditions related to red and melanized focal changes in farmed Atlantic salmon (Salmo salar). Our findings support a model where similar molecular mechanisms are involved in both red and melanized filet discolorations and genes associated with several relevant pathways show distinct expression patterns in both sample types. Interestingly, there appears to be significant cellular heterogeneity in the foci investigated when looking at gene expression patterns. Some of the genes that show differential spatial expression are involved in cellular processes such as hypoxia and immune responses, providing new insight into the nature of muscle melanization in Atlantic salmon.
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Affiliation(s)
- H Bjørgen
- Unit of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 1433, Ås, Norway
| | - S Malik
- Department of Breeding and Genetics, Nofima, 1433, Ås, Norway
| | - E Rimstad
- Unit of Virology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 1433, Ås, Norway
| | - M Vaadal
- Department of Breeding and Genetics, Nofima, 1433, Ås, Norway
| | - I B Nyman
- Unit of Virology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 1433, Ås, Norway
| | - E O Koppang
- Unit of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 1433, Ås, Norway
| | - T Tengs
- Department of Breeding and Genetics, Nofima, 1433, Ås, Norway.
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8
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Etayo A, Bjørgen H, Koppang EO, Lie KK, Bjelland RM, Hordvik I, Øvergård AC, Sæle Ø. The ontogeny of lymphoid organs and IgM + B-cells in ballan wrasse (Labrus bergylta) reveals a potential site for extrarenal B-cell lymphopoiesis: The pancreas. Fish Shellfish Immunol 2024; 144:109273. [PMID: 38072139 DOI: 10.1016/j.fsi.2023.109273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 12/04/2023] [Indexed: 12/17/2023]
Abstract
Vaccination of farmed fish is the most effective prophylactic measure against contagious diseases but requires specific knowledge on when the adaptive immune system is fully developed. The present work describes kidney and spleen morphogenesis as well as B-cell development in the ballan wrasse (Labrus bergylta). The kidney was present at hatching (0 days pot hatching, dph) but was not lymphoid before larvae was 50-60 dph (stage 5), containing abundant Igμ+ cells. The spleen anlage was first observed in larvae at 20-30 dph and was later populated with B-cells. Unexpectedly, we found strong RAG1 signal together with abundant Igμ+ and IgM + cells in the exocrine pancreas of larvae from when the kidney was lymphoid and onwards, suggesting that B-cell lymphopoiesis occurs not only in the head kidney (HK) but also in pancreatic tissue. In this agastric fish, the pancreas is diffused along the intestine and the early presence of IgM+ B-cells in pancreatic tissue might have a role in maintain immune homeostasis in the peritoneal cavity, making a substantial contribution to early protection. IgM-secreting cells in HK indicate the presence of systemic IgM at stage 5, before the first IgM+ cells were identified in mucosal sites. This work together with our previous study on T-cell development in this species indicates that although T- and B-cells start to develop around the same time, B-cells migrate to mucosal tissues ahead of T-cells. This early migration likely involves the production of natural antibodies, contributing significantly to early protection. Moreover, a diet composed of barnacle nauplii did not result in an earlier onset of B-cell lymphopoiesis, as seen in the previous study analysing T-cell development. Nevertheless, components for adaptive immunity indicating putative immunocompetence is likely achieved in early juveniles (>100 dph). Additionally, maternal transfer of IgM to the offspring is also described. These findings provide important insights into the development of the immune system in ballan wrasse and lay the foundation for optimizing prophylactic strategies in the future. Furthermore, this work adds valuable information to broaden the knowledge on the immune system in lower vertebrates.
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Affiliation(s)
- Angela Etayo
- Institute of Marine Research, Bergen, Norway; Fish Health group, Department of Biological Sciences, University of Bergen, Norway.
| | - Håvard Bjørgen
- Section of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Erling O Koppang
- Section of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Kai K Lie
- Institute of Marine Research, Bergen, Norway
| | - Reidun M Bjelland
- Institute of Marine Research, Austevoll Research Station, 5392, Storebø, Norway
| | - Ivar Hordvik
- Fish Health group, Department of Biological Sciences, University of Bergen, Norway
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Rennemo J, Berge K, Yousaf MN, Eriksen TB, Welde E, Robertsen C, Johansen B, McGurk C, Rimstad E, Koppang EO, Bjørgen H. An Atypical Course of Cardiomyopathy Syndrome (CMS) in Farmed Atlantic Salmon ( Salmo salar) Fed a Clinical Nutrition Diet. Microorganisms 2023; 12:26. [PMID: 38257853 PMCID: PMC10820600 DOI: 10.3390/microorganisms12010026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 12/19/2023] [Accepted: 12/20/2023] [Indexed: 01/24/2024] Open
Abstract
Cardiomyopathy syndrome (CMS) poses a significant threat to farmed Atlantic salmon (Salmo salar), leading to high mortality rates during the seawater phase. Given that controlled experimental challenge trials with PMCV do not reproduce the mortality observed in severe field outbreaks of CMS, field trials on natural CMS outbreaks are warranted. This field study explored the impact of a clinical nutrition intervention, specifically a diet enriched with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), on a severe CMS outbreak in a commercial sea farm. CMS was diagnosed in a single sea cage with high mortality rates. Histopathological analysis, RT-qPCR in situ hybridization for virus detection, and fatty acid composition analysis were used to monitor the impact of disease and the inclusion of EPA and DHA in heart tissue. Following the implementation of clinical nutrition, a decline in mortality rates, regression of CMS-associated changes, and a significant reduction in piscine myocarditis virus (PMCV) RNA load were observed within the salmon population. Fatty acid composition analysis of heart samples demonstrated increased levels of EPA and DHA, reinforcing the association between dietary factors, viral load dynamics, and overall fish health. Although further validation is needed in future studies, as field trials may not be sufficient to establish causation, our results indicate that optimizing the EPA + DHA levels may prove beneficial in severe CMS outbreaks.
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Affiliation(s)
- Johan Rennemo
- Skretting AS, 4016 Stavanger, Norway; (J.R.); (K.B.)
| | - Kjetil Berge
- Skretting AS, 4016 Stavanger, Norway; (J.R.); (K.B.)
| | - Muhammad Naveed Yousaf
- Skretting Aquaculture Innovation (AI), 4016 Stavanger, Norway; (M.N.Y.); (T.B.E.); (C.M.)
| | - Tommy Berger Eriksen
- Skretting Aquaculture Innovation (AI), 4016 Stavanger, Norway; (M.N.Y.); (T.B.E.); (C.M.)
| | - Eirik Welde
- Nordlaks Havbruk AS, 8455 Stokmarknes, Norway; (E.W.); (C.R.); (B.J.)
| | - Camilla Robertsen
- Nordlaks Havbruk AS, 8455 Stokmarknes, Norway; (E.W.); (C.R.); (B.J.)
| | - Bjarne Johansen
- Nordlaks Havbruk AS, 8455 Stokmarknes, Norway; (E.W.); (C.R.); (B.J.)
| | - Charles McGurk
- Skretting Aquaculture Innovation (AI), 4016 Stavanger, Norway; (M.N.Y.); (T.B.E.); (C.M.)
| | - Espen Rimstad
- Unit of Virology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 1432 Ås, Norway;
| | - Erling Olaf Koppang
- Unit of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 1432 Ås, Norway;
| | - Håvard Bjørgen
- Unit of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 1432 Ås, Norway;
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10
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Brimsholm M, Fjelldal PG, Hansen T, Fraser TKW, Solberg M, Glover K, Koppang EO, Bjørgen H. Red and melanized focal changes in white skeletal muscle in Atlantic salmon (Salmo salar): Comparative analysis of farmed, wild and hybrid fish reared under identical conditions. J Fish Dis 2023; 46:1377-1389. [PMID: 37675872 DOI: 10.1111/jfd.13856] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 08/16/2023] [Accepted: 08/22/2023] [Indexed: 09/08/2023]
Abstract
Selective breeding plays a vital role in the production of farmed Atlantic salmon and has shown success in many aspects. Still, challenges related to fish health and welfare continue to result in significant economic losses. One such challenge is red and melanized focal changes (RFC/MFC), which result from acute and chronic inflammation, respectively, in the skeletal muscle. Importantly, RFC/MFC has not been observed in wild Atlantic salmon, suggesting that both external and genetic factors may contribute to the development of inflammation. To investigate the underlying cause of RFC/MFC, we conducted a study involving 1854 Atlantic salmon of farmed, wild and hybrid origin. All fish were reared under identical conditions to minimize the influence of external factors. Throughout the production cycle, the fish was monitored for growth parameters and examined for RFC/MFC using macroscopic and histological analysis. We found no association between the experimental groups and the presence of RFC/MFC. Histological investigations revealed melano-macrophages in the soft tissue in freshwater smolt, although no macroscopic discoloration was observed. MFC showed granulomas in various stages, suggesting a complex progression of the condition. In summary, we conclude that RFC/MFC is primarily caused by external factors found in the rearing facilities of farmed Atlantic salmon.
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Affiliation(s)
- Malin Brimsholm
- Unit of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | | | - Tom Hansen
- Matre Research Station, Institute of Marine Research, Matredal, Norway
| | | | - Monica Solberg
- Population Genetics Research Group, Institute of Marine Research, Bergen, Norway
| | - Kevin Glover
- Population Genetics Research Group, Institute of Marine Research, Bergen, Norway
| | - Erling Olaf Koppang
- Unit of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Håvard Bjørgen
- Unit of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
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11
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Castro PL, Barac F, Hansen TJ, Fjelldal PG, Hordvik I, Bjørgen H, Koppang EO. The Distribution of IgT mRNA + Cells in the Gut of the Atlantic Salmon ( Salmo salar L.). Animals (Basel) 2023; 13:3191. [PMID: 37893915 PMCID: PMC10603744 DOI: 10.3390/ani13203191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 10/01/2023] [Accepted: 10/07/2023] [Indexed: 10/29/2023] Open
Abstract
The newly discovered IgT+ B cell is thought to play a dominant role in mucosal immunity, but limited studies have examined its distribution in fish species, hindering our understanding of its function. This study investigated IgT and poly Ig receptor (pIgR) mRNA+ cell distribution in Atlantic salmon (Salmo salar) gut using RNAscope in situ hybridization (ISH) and assessed the effects of vaccination. The pyloric caeca, mid-intestine (first and second parts), and posterior segment in two weight stages (Group 1: avg. 153 g, Group 2: avg. 1717 g) were examined in both vaccinated and unvaccinated fish. ISH revealed more IgT mRNA+ cells in the second part of the midgut compared to other intestinal segments, as well as a higher number of positive cells in Group 2 (older fish). In line with previous findings, intraperitoneal vaccination had no significant impact on the number of IgT+ transcripts. IgT mRNA+ cells were found mostly in the lamina propria and near capillaries, while pIgR was registered in both the lamina propria and mucosa. Interestingly, vaccinated fish presented adhesions and granulomatous tissue in the peritoneum, with both IgT and pIgR mRNA+ cells. Taken together, these results suggest that the distribution of IgT mRNA+ cells in the intestine of Atlantic salmon is region-specific and is not affected by intraperitoneal vaccination but varies with fish age.
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Affiliation(s)
- Pedro Luis Castro
- GIA-ECOAQUA, Universidad de Las Palmas de Gran Canaria, 35001 Telde, Spain
| | - Fran Barac
- Unit of Anatomy, Veterinary Faculty, Norwegian University of Life Sciences, 1433 Ås, Norway; (F.B.); (H.B.); (E.O.K.)
| | - Tom Johnny Hansen
- Matre Research Station, Institute of Marine Research, 5984 Matredal, Norway; (T.J.H.); (P.G.F.)
| | - Per Gunnar Fjelldal
- Matre Research Station, Institute of Marine Research, 5984 Matredal, Norway; (T.J.H.); (P.G.F.)
| | - Ivar Hordvik
- Institute of Biology, University of Bergen, 5007 Bergen, Norway;
| | - Håvard Bjørgen
- Unit of Anatomy, Veterinary Faculty, Norwegian University of Life Sciences, 1433 Ås, Norway; (F.B.); (H.B.); (E.O.K.)
| | - Erling Olaf Koppang
- Unit of Anatomy, Veterinary Faculty, Norwegian University of Life Sciences, 1433 Ås, Norway; (F.B.); (H.B.); (E.O.K.)
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12
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Brimsholm M, Rønning L, Rimstad E, Koppang EO, Bjørgen H. Diffuse melanization of the red skeletal musculature in farmed Atlantic salmon (Salmo salar L.). J Fish Dis 2023; 46:453-458. [PMID: 36353756 DOI: 10.1111/jfd.13729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 10/14/2022] [Accepted: 10/18/2022] [Indexed: 06/16/2023]
Affiliation(s)
- Malin Brimsholm
- Unit of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | | | - Espen Rimstad
- Unit of Virology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Erling Olaf Koppang
- Unit of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Håvard Bjørgen
- Unit of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
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13
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Brimsholm M, Fjelldal PG, Hansen T, Trangerud C, Knutsen GM, Asserson CF, Koppang EO, Bjørgen H. Anatomical and pathological characteristics of ribs in the Atlantic salmon (Salmo salar L.) and its relevance to soft tissue changes. Anat Histol Embryol 2023; 52:421-436. [PMID: 36637047 DOI: 10.1111/ahe.12900] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 12/21/2022] [Indexed: 01/14/2023]
Abstract
Studies on the anatomical and pathological characteristics of ribs in farmed Atlantic salmon (Salmo salar L.) are warranted due to their possible association with red and melanized focal changes (RFC and MFC) in the fillet, a major quality and animal welfare concern. In this work, we provide an anatomical description of ribs based on radiographical and histological analyses. We also address various pathological rib changes and their association to RFC and MFC. In total, 129 fish were investigated; captured wild (n = 10) and hatchery reared (n = 119) Atlantic salmon (3.5-6.1 kg). The fish were selected based on the macroscopic presence of RFC, MFC or no changes (controls). Radiographic results revealed costal abnormalities in all fish groups. By histological investigations of the variations herein, our results provide new insight into the anatomical characteristics including vascularization within the ribs; a potential site for haemorrhage following costal fractures. Costal fractures were detected by radiology in 40 of 129 samples (RFC: 38.4%, MFC: 47.2%, controls: 9.5 %). A statistically significant association was found between costal fractures and red (p = 0.007) and melanized changes (p = 0.000). However, red and melanized changes were also observed in samples with no costal fractures (n = 45), indicating that also other factors influence the development of RFC/MFC.
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Affiliation(s)
- Malin Brimsholm
- Unit of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | | | - Tom Hansen
- Matre Research Station, Institute of Marine Research, Matredal, Norway
| | - Cathrine Trangerud
- Unit of Radiology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | | | | | - Erling Olaf Koppang
- Unit of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Håvard Bjørgen
- Unit of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
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14
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Rennemo J, Myrvold S, Berge K, Kileng Ø, Pedersen B, Aksberg DS, Lisik P, Crappe D, McGurk C, Rimstad E, Wessel Ø, Koppang EO, Bjørgen H. In-depth health surveillance and clinical nutrition in farmed Atlantic salmon: a strategic attempt to detect and mitigate an HSMI outbreak. Vet Res 2023; 54:3. [PMID: 36694262 PMCID: PMC9872415 DOI: 10.1186/s13567-023-01137-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 12/07/2022] [Indexed: 01/26/2023] Open
Abstract
Fish health personnel have limited tools in combatting viral diseases such as heart and skeletal muscle inflammation (HSMI) in open net-pen farmed Atlantic salmon. In this study, we aimed to predict HSMI by intensified health monitoring and apply clinical nutrition to mitigate the condition. We followed a commercial cohort (G1) of Atlantic salmon that was PRV-1 naïve when transferred to a sea cage at a location where HSMI outbreaks commonly occur. The fish in the other cages (G2-G6) at the location had a different origin than G1 and were PRV-1 positive prior to sea transfer. By continuous analysis of production data and sequentially (approximately every fourth week) performing autopsy, RT-qPCR (for PRV-1 and selected immune genes), blood and histological analysis of 10 fish from G1 and G2, we identified the time of PRV-1 infection in G1 and predicted the onset of HSMI prior to any clinical signs of disease. Identical sequences across partial genomes of PRV-1 isolates from G1 and G2 suggest the likely transfer from infected cages to G1. The isolates were grouped into a genogroup known to be of high virulence. A commercial health diet was applied during the HSMI outbreak, and the fish had low mortality and an unaffected appetite. In conclusion, we show that fish health and welfare can benefit from in-depth health monitoring. We also discuss the potential health value of clinical nutrition as a mean to mitigate HSMI.
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Affiliation(s)
- Johan Rennemo
- grid.436785.b0000 0004 0644 9116Skretting AS, Stavanger, Norway
| | | | - Kjetil Berge
- grid.436785.b0000 0004 0644 9116Skretting AS, Stavanger, Norway
| | | | - Børge Pedersen
- grid.436785.b0000 0004 0644 9116Skretting AS, Stavanger, Norway
| | | | - Piotr Lisik
- Skretting Aquaculture Innovation (AI), Stavanger, Norway
| | | | - Charles McGurk
- Skretting Aquaculture Innovation (AI), Stavanger, Norway
| | - Espen Rimstad
- grid.19477.3c0000 0004 0607 975XUnit of Virology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 1433 Ås, Norway
| | - Øystein Wessel
- grid.19477.3c0000 0004 0607 975XUnit of Virology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 1433 Ås, Norway
| | - Erling Olaf Koppang
- grid.19477.3c0000 0004 0607 975XUnit of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 1433 Ås, Norway
| | - Håvard Bjørgen
- grid.19477.3c0000 0004 0607 975XUnit of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 1433 Ås, Norway
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15
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Bjørgen H, Oaland Ø, Midtllyng P, Tafalla C, Krogdahl Å, Koppang EO. IgD-transcript positive cells suggest hypersensitivity in feed-related intestinal inflammation in the Atlantic salmon. Fish Shellfish Immunol 2023; 132:108469. [PMID: 36528310 DOI: 10.1016/j.fsi.2022.108469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 11/25/2022] [Accepted: 11/30/2022] [Indexed: 06/17/2023]
Affiliation(s)
- Håvard Bjørgen
- Unit of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | | | - Paul Midtllyng
- Aquamedic AS, Ullevålsveien 68, Bygn. 23, 0454, Oslo, Norway
| | - Carolina Tafalla
- Animal Health Research Center (CISA), Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Consejo Superior de Investigaciones Científicas (CSIC), Valdeolmos, 28130, Madrid, Spain
| | - Åshild Krogdahl
- Unit of Nutrition and Health, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Erling Olaf Koppang
- Unit of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway.
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16
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Etayo A, Bjørgen H, Koppang EO, Hordvik I. The teleost polymeric Ig receptor counterpart in ballan wrasse (Labrus bergylta) differs from pIgR in higher vertebrates. Vet Immunol Immunopathol 2022; 249:110440. [DOI: 10.1016/j.vetimm.2022.110440] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 04/22/2022] [Accepted: 05/10/2022] [Indexed: 12/23/2022]
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17
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Dalum AS, Kraus A, Khan S, Davydova E, Rigaudeau D, Bjørgen H, López-Porras A, Griffiths G, Wiegertjes GF, Koppang EO, Salinas I, Boudinot P, Rességuier J. High-Resolution, 3D Imaging of the Zebrafish Gill-Associated Lymphoid Tissue (GIALT) Reveals a Novel Lymphoid Structure, the Amphibranchial Lymphoid Tissue. Front Immunol 2021; 12:769901. [PMID: 34880866 PMCID: PMC8647647 DOI: 10.3389/fimmu.2021.769901] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 10/25/2021] [Indexed: 12/24/2022] Open
Abstract
The zebrafish is extensively used as an animal model for human and fish diseases. However, our understanding of the structural organization of its immune system remains incomplete, especially the mucosa-associated lymphoid tissues (MALTs). Teleost MALTs are commonly perceived as diffuse and scattered populations of immune cells throughout the mucosa. Yet, structured MALTs have been recently discovered in Atlantic salmon (Salmo salar L.), including the interbranchial lymphoid tissue (ILT) in the gills. The existence of the ILT was only recently identified in zebrafish and other fish species, highlighting the need for in-depth characterizations of the gill-associated lymphoid tissue (GIALT) in teleosts. Here, using 3-D high-resolution microscopy, we analyze the GIALT of adult zebrafish with an immuno-histology approach that reveals the organization of lymphoid tissues via the labeling of T/NK cells with an antibody directed to a highly conserved epitope on the kinase ZAP70. We show that the GIALT in zebrafish is distributed over at least five distinct sub-regions, an organization found in all pairs of gill arches. The GIALT is diffuse in the pharyngeal part of the gill arch, the interbranchial septum and the filaments/lamellae, and structured in two sub-regions: the ILT, and a newly discovered lymphoid structure located along each side of the gill arch, which we named the Amphibranchial Lymphoid Tissue (ALT). Based on RAG2 expression, neither the ILT nor the ALT constitute additional thymi. The ALT shares several features with the ILT such as presence of abundant lymphoid cells and myeloid cells embedded in a network of reticulated epithelial cells. Further, the ILT and the ALT are also a site for T/NK cell proliferation. Both ILT and ALT show structural changes after infection with Spring Viraemia of Carp Virus (SVCV). Together, these data suggest that ALT and ILT play an active role in immune responses. Comparative studies show that whereas the ILT seems absent in most neoteleosts ("Percomorphs"), the ALT is widely present in cyprinids, salmonids and neoteleosts, suggesting that it constitutes a conserved tissue involved in the protection of teleosts via the gills.
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Affiliation(s)
- Alf S. Dalum
- Nofima, Norwegian Institute of Food, Fisheries and Aquaculture Research, Ås, Norway
| | - Aurora Kraus
- Center for Evolutionary and Theoretical Immunology (CETI), Department of Biology, University of New Mexico, Albuquerque, NM, United States
| | - Shanawaz Khan
- Department of Biosciences, FYSCELL, University of Oslo, Oslo, Norway
| | - Erna Davydova
- Department of Biosciences, BMB, University of Oslo, Oslo, Norway
| | | | - Håvard Bjørgen
- Section of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | | | - Gareth Griffiths
- Department of Biosciences, FYSCELL, University of Oslo, Oslo, Norway
| | - Geert F. Wiegertjes
- Aquaculture and Fisheries Group, Department of Animal Sciences, Wageningen University & Research, Wageningen, Netherlands
| | - Erling O. Koppang
- Section of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Irene Salinas
- Center for Evolutionary and Theoretical Immunology (CETI), Department of Biology, University of New Mexico, Albuquerque, NM, United States
| | - Pierre Boudinot
- INRAE, UVSQ, VIM, Université Paris-Saclay, Jouy-en-Josas, France
| | - Julien Rességuier
- Department of Biosciences, FYSCELL, University of Oslo, Oslo, Norway
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18
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Abstract
The function of a tissue is determined by its construction and cellular composition. The action of different genes can thus only be understood properly when seen in the context of the environment in which they are expressed and function. We now experience a renaissance in morphological research in fish, not only because, surprisingly enough, large structures have remained un-described until recently, but also because improved methods for studying morphological characteristics in combination with expression analysis are at hand. In this review, we address anatomical features of teleost immune tissues. There are approximately 30,000 known teleost fish species and only a minor portion of them have been studied. We aim our review at the Atlantic salmon (Salmo salar) and other salmonids, but when applicable, we also present information from other species. Our focus is the anatomy of the kidney, thymus, spleen, the interbranchial lymphoid tissue (ILT), the newly discovered salmonid cloacal bursa and the naso-pharynx associated lymphoid tissue (NALT).
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Affiliation(s)
- Håvard Bjørgen
- Section of Anatomy, The Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ullevålsveien 72, Oslo, Norway
| | - Erling Olaf Koppang
- Section of Anatomy, The Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ullevålsveien 72, Oslo, Norway.
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19
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Persson D, Bjørgen H, Figenschou A, Hillestad LA, Koppang EO, Nødtvedt A, Stormoen M. Variations in mucous cell numbers in gills of Atlantic salmon (Salmo salar) presmolt in commercial freshwater farms in Norway. J Fish Dis 2021; 44:25-32. [PMID: 33070329 DOI: 10.1111/jfd.13263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 08/18/2020] [Accepted: 08/19/2020] [Indexed: 06/11/2023]
Abstract
Fish gills are heavily exposed to the external milieu and may react against irritants with different cellular responses. We describe variations in mucous cell counts in gills from healthy Atlantic salmon (Salmo salar) presmolts in five recirculating aquaculture system (RAS) farms and one flow-through farm. Based on certain criteria, mucous cells were histologically quantified in a defined lamellar region of the gills and the counts were analysed. Immunohistochemistry (IHC) was used to investigate epithelial responses. The median number of total mucous cells in the defined region was 59 per fish. Between the farms, the medians varied from 31 to 101 with the lowest in the flow-through farm. A regression model was fitted with "total mucous cells" as the dependent variable and with "fish length" and "fish farm" as independent variables. The proportion of variation in mucous cell counts explained by the model was twice as high when "fish farm" was included compared to only "fish length." IHC revealed proliferative responses in coherence with high mucous cell numbers. Conclusively, the variation in mucous cell counts depends on combined farm-related factors. Establishing a baseline for mucous cell counts is fundamental in the development of high-throughput monitoring programmes of gill health in farmed fish.
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Affiliation(s)
- David Persson
- Department of Production Animal Clinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Håvard Bjørgen
- Section of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Alexander Figenschou
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Linn-Anett Hillestad
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Erling Olaf Koppang
- Section of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Ane Nødtvedt
- Department of Production Animal Clinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Marit Stormoen
- Department of Production Animal Clinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
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20
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Malik MS, Bjørgen H, Nyman IB, Wessel Ø, Koppang EO, Dahle MK, Rimstad E. PRV-1 Infected Macrophages in Melanized Focal Changes in White Muscle of Atlantic Salmon ( Salmo salar) Correlates With a Pro-Inflammatory Environment. Front Immunol 2021; 12:664624. [PMID: 33995395 PMCID: PMC8116804 DOI: 10.3389/fimmu.2021.664624] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 04/13/2021] [Indexed: 12/27/2022] Open
Abstract
Melanized focal changes in white skeletal muscle of farmed Atlantic salmon, "black spots", is a quality problem affecting on average 20% of slaughtered fish. The spots appear initially as "red spots" characterized by hemorrhages and acute inflammation and progress into black spots characterized by chronic inflammation and abundant pigmented cells. Piscine orthoreovirus 1 (PRV-1) was previously found to be associated with macrophages and melano-macrophages in red and black spots. Here we have addressed the inflammatory microenvironment of red and black spots by studying the polarization status of the macrophages and cell mediated immune responses in spots, in both PRV-1 infected and non-infected fish. Samples that had been collected at regular intervals through the seawater production phase in a commercial farm were analyzed by multiplex fluorescent in situ hybridization (FISH) and RT-qPCR methods. Detection of abundant inducible nitric oxide synthase (iNOS2) expressing M1-polarized macrophages in red spots demonstrated a pro-inflammatory microenvironment. There was an almost perfect co-localization with the iNOS2 expression and PRV-1 infection. Black spots, on the other side, had few iNOS2 expressing cells, but a relatively high number of arginase-2 expressing anti-inflammatory M2-polarized macrophages containing melanin. The numerous M2-polarized melano-macrophages in black spots indicate an ongoing healing phase. Co-localization of PRV-1 and cells expressing CD8+ and MHC-I suggests a targeted immune response taking place in the spots. Altogether, this study indicates that PRV-1 induces a pro-inflammatory environment that is important for the pathogenesis of the spots. We do not have indication that infection of PRV-1 is the initial causative agent of this condition.
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Affiliation(s)
- Muhammad Salman Malik
- Section of Virology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Håvard Bjørgen
- Section of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Ingvild Berg Nyman
- Section of Virology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Øystein Wessel
- Section of Virology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Erling Olaf Koppang
- Section of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Maria K. Dahle
- Department of Fish Health, Norwegian Veterinary Institute, Oslo, Norway
| | - Espen Rimstad
- Section of Virology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
- *Correspondence: Espen Rimstad,
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21
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Bjørgen H, Li Y, Kortner TM, Krogdahl Å, Koppang EO. Anatomy, immunology, digestive physiology and microbiota of the salmonid intestine: Knowns and unknowns under the impact of an expanding industrialized production. Fish Shellfish Immunol 2020; 107:172-186. [PMID: 32979510 DOI: 10.1016/j.fsi.2020.09.032] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 09/18/2020] [Accepted: 09/21/2020] [Indexed: 06/11/2023]
Abstract
Increased industrialized production of salmonids challenges aspects concerning available feed resources and animal welfare. The immune system plays a key component in this respect. Novel feed ingredients may trigger unwarranted immune responses again affecting the well-being of the fish. Here we review our current knowledge concerning salmon intestinal anatomy, immunity, digestive physiology and microbiota in the context of industrialized feeding regimes. We point out knowledge gaps and indicate promising novel technologies to improve salmonid intestinal health.
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Affiliation(s)
- Håvard Bjørgen
- Section of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Yanxian Li
- Nutrition and Health Unit, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Trond M Kortner
- Nutrition and Health Unit, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Åshild Krogdahl
- Nutrition and Health Unit, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Erling Olaf Koppang
- Section of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
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22
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Bakke AF, Bjørgen H, Koppang EO, Frost P, Afanasyev S, Boysen P, Krasnov A, Lund H. IgM+ and IgT+ B Cell Traffic to the Heart during SAV Infection in Atlantic Salmon. Vaccines (Basel) 2020; 8:E493. [PMID: 32878234 PMCID: PMC7563723 DOI: 10.3390/vaccines8030493] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 08/24/2020] [Accepted: 08/24/2020] [Indexed: 02/02/2023] Open
Abstract
B cells of teleost fish differentiate in the head kidney, and spleen, and either remain in the lymphatic organs or move to the blood and peripheral tissues. There is limited knowledge about piscine B cell traffic to sites of vaccination and infection and their functional roles at these sites. In this work, we examined the traffic of B cells in Atlantic salmon challenged with salmonid alphavirus (SAV). In situ hybridization (RNAScope) showed increased numbers of immunoglobin (Ig)M+ and IgT+ B cells in the heart in response to SAV challenge, with IgM+ B cells being most abundant. An increase in IgT+ B cells was also evident, indicating a role of IgT+ B cells in nonmucosal tissues and systemic viral infections. After infection, B cells were mainly found in the stratum spongiosum of the cardiac ventricle, colocalizing with virus-infected myocardial-like cells. From sequencing the variable region of IgM in the main target organ (heart) and comparing it with a major lymphatic organ (the spleen), co-occurrence in antibody repertoires indicated a transfer of B cells from the spleen to the heart, as well as earlier recruitment of B cells to the heart in vaccinated fish compared to those that were unvaccinated. Transcriptome analyses performed at 21 days post-challenge suggested higher expression of multiple mediators of inflammation and lymphocyte-specific genes in unvaccinated compared to vaccinated fish, in parallel with a massive suppression of genes involved in heart contraction, metabolism, and development of tissue. The adaptive responses to SAV in vaccinated salmon appeared to alleviate the disease. Altogether, these results suggest that migration of B cells from lymphatic organs to sites of infection is an important part of the adaptive immune response of Atlantic salmon to SAV.
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Affiliation(s)
- Anne Flore Bakke
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), Ullevålsveien 72, 0454 Oslo, Norway; (A.F.B.); (H.B.); (E.O.K.); (P.B.); (H.L.)
| | - Håvard Bjørgen
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), Ullevålsveien 72, 0454 Oslo, Norway; (A.F.B.); (H.B.); (E.O.K.); (P.B.); (H.L.)
| | - Erling Olaf Koppang
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), Ullevålsveien 72, 0454 Oslo, Norway; (A.F.B.); (H.B.); (E.O.K.); (P.B.); (H.L.)
| | - Petter Frost
- MSD Animal Health Innovation AD, Thormøhlens Gate 55, 5006 Bergen, Norway;
| | - Sergey Afanasyev
- I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Torez 44, Saint-Petersburg 194223, Russia;
| | - Preben Boysen
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), Ullevålsveien 72, 0454 Oslo, Norway; (A.F.B.); (H.B.); (E.O.K.); (P.B.); (H.L.)
| | | | - Hege Lund
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), Ullevålsveien 72, 0454 Oslo, Norway; (A.F.B.); (H.B.); (E.O.K.); (P.B.); (H.L.)
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Bjørgen H, Kumar S, Gunnes G, Press CM, Rimstad E, Koppang EO. Immunopathological characterization of red focal changes in Atlantic salmon (Salmo salar) white muscle. Vet Immunol Immunopathol 2020; 222:110035. [PMID: 32200172 DOI: 10.1016/j.vetimm.2020.110035] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 02/26/2020] [Accepted: 03/06/2020] [Indexed: 11/18/2022]
Abstract
Farmed Atlantic salmon (Salmo salar) are prone to various conditions affecting the quality of the fillet. A well-known but so far poorly understood condition is the focal red changes in muscle, often referred to as haemorrhages. Such changes are characterized by muscle necrosis, haemorrhages and acute inflammation. They can progress into focal melanised changes, a chronic inflammatory condition with melanin-producing leukocytes. The initial cause of intramuscular haemorrhages is unknown. In this study, we aimed to reveal some of their key immunological features. Samples of red focal changes were investigated by immunohistochemistry (IHC), in situ hybridization (ISH) and RT-qPCR for various immune markers. The results were compared with samples of melanised changes and control muscle, subjected to the same analyses. In all red changes, infiltrates with mononuclear cells were detected, consisting mostly of MHC class I/II+ cells, but also of CD3+ and CD8+ cells. ISH studies on IgM showed few to moderate amounts of B-cells in red focal changes. Trends in the RT-qPCR showed upregulation of genes related to innate immunity in the red changes, whereas genes related to adaptive immunity were upregulated in the melanised changes. An important result was the significant downregulation of the anti-inflammatory cytokine IL10 in all red changes. Our findings indicate that we can rule out an auto invasive nature of the changes. The downregulation of IL10 at an early phase is a trait for the condition.
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Affiliation(s)
- Håvard Bjørgen
- Department of Basic Science and Aquatic Medicine, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
| | - Subramani Kumar
- Centre for Biotechnology, Anna University, Chennai, 600 025, India.
| | - Gjermund Gunnes
- Department of Basic Science and Aquatic Medicine, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
| | - Charles McL Press
- Department of Basic Science and Aquatic Medicine, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
| | - Espen Rimstad
- Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
| | - Erling Olaf Koppang
- Department of Basic Science and Aquatic Medicine, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
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24
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Trangerud C, Bjørgen H, Koppang EO, Grøntvedt RN, Skogmo HK, Ottesen N, Kvellestad A. Vertebral column deformity with curved cross-stitch vertebrae in Norwegian seawater-farmed Atlantic salmon, Salmo salar L. J Fish Dis 2020; 43:379-389. [PMID: 31970816 DOI: 10.1111/jfd.13136] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 12/27/2019] [Accepted: 12/27/2019] [Indexed: 06/10/2023]
Abstract
Pathological changes in the vertebral column of farmed Atlantic salmon in Norway have been reported since the 1990s. Based on the characteristic radiographic findings, we here present a vertebral column deformity named "curved cross-stitch vertebrae" that mainly affects the middle aspect of the vertebral column. Sixty fish, from the west/northwest coast of mid-Norway, were sampled at slaughter and examined by radiography, computed tomography (CT), necropsy, macrophotography, and histology. The vertebral deformities were radiographically graded as mild, moderate, or marked. The main differences between these grades of changes were defined by increased curving of the peripheries of endplates, reduced intervertebral spaces, and vertical displacement of the vertebrae. The curved rims of endplates were located peripheral to a continuous and approximately circular borderline. The CT studies revealed small, multifocal, hypo-attenuating, round to crescent-shaped areas in the notochord, compatible with the presence of gas. Additionally, histology revealed that the axial parts of endplates had circular zones with perforations, through which either notochordal tissue prolapsed into the vertebrae or vascularized fibrochondroid proliferations extended from the vertebrae into the notochord. Inflammation was present in many vertebral bodies. To the best of our knowledge, this is the first report of gas in the notochord of fish.
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Affiliation(s)
- Cathrine Trangerud
- Department of Companion Animal Clinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Håvard Bjørgen
- Section of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Erling Olaf Koppang
- Section of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | | | - Hege Kippenes Skogmo
- Department of Companion Animal Clinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Nina Ottesen
- Department of Companion Animal Clinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Agnar Kvellestad
- Section of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
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Abstract
The bursa of Fabricius is a primary and secondary lymphoid organ considered exclusively present in birds, and studies of this structure have been vital to our current understanding of the adaptive immune system of vertebrates. In this study, we reveal substantial lymphoepithelial tissue in a previously undescribed bursa in Atlantic salmon (Salmo salar), situated caudal to the urogenital papilla of the cloaca and thus analogous to the anatomical placement of the bursa of Fabricius. We investigated three groups of Atlantic salmon at different maturational stages and characterized the structure by applying dissection, radiology, scanning electron microscopy and histological techniques, including immunohistochemistry and in situ hybridization. We found that the epithelial anlage of the salmon cloacal bursa developed into substantial lymphoepithelial tissue and subsequently regressed following sexual maturation. Such a dynamic development is also a key characteristic of the avian bursa. The presence of intraepithelial lymphocytes was concomitant with expression of the leukocyte-attracting chemokine CCL19, indicative of lymphoid organ functions. We did not observe recombination or gene conversion in salmon bursal lymphocytes at any developmental stage, indicating the absence of primary lymphoid organ functions in contrast to the bursa of Fabricius. However, the possibility of the bursa to trap both enteric and environmental antigens, combined with the presence of several antigen-presenting cells residing within the lymphoepithelium, suggest the structure has secondary lymphoid organ functions. We present the discovery of a lymphoid organ in Atlantic salmon with striking topographical similarities to that of the bursa of Fabricius in birds. In addition, the age-dependent dynamics of its lymphoepithelium suggest functions related to the maturation processes of lymphocytes.
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Affiliation(s)
- Oskar M Løken
- Section of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Håvard Bjørgen
- Section of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Ivar Hordvik
- Institute of Biology, University of Bergen, Bergen, Norway
| | - Erling O Koppang
- Section of Anatomy, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
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26
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Bjørgen H, Løken OM, Aas IB, Fjelldal PG, Hansen T, Austbø L, Koppang EO. Visualization of CCL19-like transcripts in the ILT, thymus and head kidney of Atlantic salmon (Salmo salar L.). Fish Shellfish Immunol 2019; 93:763-765. [PMID: 31422180 DOI: 10.1016/j.fsi.2019.08.044] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 08/12/2019] [Accepted: 08/14/2019] [Indexed: 06/10/2023]
Affiliation(s)
- Håvard Bjørgen
- Section of Anatomy and Pathology, Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ullevålsveien 72, Oslo, Norway
| | - Oskar Mongstad Løken
- Section of Anatomy and Pathology, Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ullevålsveien 72, Oslo, Norway
| | - Ida Bergva Aas
- Section of Anatomy and Pathology, Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ullevålsveien 72, Oslo, Norway
| | | | - Tom Hansen
- Matre Research Station, Institute of Marine Research, 5498, Matre, Norway
| | - Lars Austbø
- Section of Anatomy and Pathology, Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ullevålsveien 72, Oslo, Norway
| | - Erling Olaf Koppang
- Section of Anatomy and Pathology, Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ullevålsveien 72, Oslo, Norway.
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27
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Malik MS, Bjørgen H, Dhamotharan K, Wessel Ø, Koppang EO, Di Cicco E, Hansen EF, Dahle MK, Rimstad E. Erythroid Progenitor Cells in Atlantic Salmon ( Salmo salar) May Be Persistently and Productively Infected with Piscine Orthoreovirus (PRV). Viruses 2019; 11:E824. [PMID: 31491892 PMCID: PMC6784031 DOI: 10.3390/v11090824] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 08/30/2019] [Accepted: 09/03/2019] [Indexed: 12/13/2022] Open
Abstract
Piscine orthoreovirus (PRV-1) can cause heart and skeletal muscle inflammation (HSMI) in farmed Atlantic salmon (Salmo salar). The virus targets erythrocytes in the acute peak phase, followed by cardiomyocytes, before the infection subsides into persistence. The persistent phase is characterized by high level of viral RNA, but low level of viral protein. The origin and nature of persistent PRV-1 are not clear. Here, we analyzed for viral persistence and activity in various tissues and cell types in experimentally infected Atlantic salmon. Plasma contained PRV-1 genomic dsRNA throughout an 18-week long infection trial, indicating that viral particles are continuously produced and released. The highest level of PRV-1 RNA in the persistent phase was found in kidney. The level of PRV-1 ssRNA transcripts in kidney was significantly higher than that of blood cells in the persistent phase. In-situ hybridization assays confirmed that PRV-1 RNA was present in erythroid progenitor cells, erythrocytes, macrophages, melano-macrophages and in some additional un-characterized cells in kidney. These results show that PRV-1 establishes a productive, persistent infection in Atlantic salmon and that erythrocyte progenitor cells are PRV target cells.
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Affiliation(s)
- Muhammad Salman Malik
- Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 0454 Oslo, Norway.
| | - Håvard Bjørgen
- Department of Basic Science and Aquatic Medicine, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 0454 Oslo, Norway.
| | - Kannimuthu Dhamotharan
- Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 0454 Oslo, Norway.
| | - Øystein Wessel
- Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 0454 Oslo, Norway.
| | - Erling Olaf Koppang
- Department of Basic Science and Aquatic Medicine, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 0454 Oslo, Norway.
| | - Emiliano Di Cicco
- Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, BC V9T 6N7, Canada.
| | - Elisabeth F Hansen
- Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 0454 Oslo, Norway.
| | - Maria K Dahle
- Department of Fish Health, Norwegian Veterinary Institute, 0454 Oslo, Norway
| | - Espen Rimstad
- Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 0454 Oslo, Norway.
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28
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Bjørgen H, Hellberg H, Løken OM, Gunnes G, Koppang EO, Dale OB. Tumor microenvironment and stroma in intestinal adenocarcinomas and associated metastases in Atlantic salmon broodfish (Salmo salar). Vet Immunol Immunopathol 2019; 214:109891. [PMID: 31378219 DOI: 10.1016/j.vetimm.2019.109891] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 06/26/2019] [Accepted: 07/03/2019] [Indexed: 01/12/2023]
Abstract
Animal models are invaluable tools in cancer research. In this context, salmon is a promising candidate. Intestinal adenocarcinoma with metastases may be induced as a consequence of a plant-based diet triggering the inflammation - dysplasia- carcinogenesis pathway. Here, we investigate the stroma and the presence and nature of immune cells in such tumors by staining for mast cells, immunohistochemistry for T cells and antigen-presenting cells and in situ hybridization for B cells. In intestinal tumors, substantial amounts of T cells were detected in the stroma, whilst MHC class II+ cells were mainly among the cancerous cells. Ig+ cells were observed primarily in the tumor periphery. Mast cells showed a strong association with stroma. In metastases, scarce amounts of T cells were detected, whilst MHC I and II-reactivity varied, some tumors being completely negative. Ig+ cells were scattered around the metastatic tissue in no particular pattern, but were occasionally observed within clusters of tumor cells. Small numbers of mast cells were detected in the stroma. To the best of our knowledge, this is the first report addressing immune cells in fish tumors. The teleost tumor microenvironment seems comparable to that of mammals, making fish interesting model animals in oncoimmunology research.
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Affiliation(s)
- Håvard Bjørgen
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
| | | | - Oskar Mongstad Løken
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
| | - Gjermund Gunnes
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
| | - Erling Olaf Koppang
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
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29
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Bjørgen H, Haldorsen R, Oaland Ø, Kvellestad A, Kannimuthu D, Rimstad E, Koppang EO. Melanized focal changes in skeletal muscle in farmed Atlantic salmon after natural infection with Piscine orthoreovirus (PRV). J Fish Dis 2019; 42:935-945. [PMID: 30972792 PMCID: PMC6850454 DOI: 10.1111/jfd.12995] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 03/05/2019] [Accepted: 03/06/2019] [Indexed: 06/09/2023]
Abstract
Melanized focal changes in skeletal muscle of farmed Atlantic salmon (Salmo salar) are a major quality problem. The aetiology is unknown, but infection with Piscine orthoreovirus (PRV) has been associated with the condition. Here, we addressed the pathogenesis of red and melanized focal changes and their association with PRV. First, a population of farmed fish (PRV-negative prior to sea transfer) was sequentially investigated throughout the seawater period. The fish were autopsied and tested for PRV infection. Muscular changes were described by macroscopy and histology, and a classification system was established. Second, in an experimental infection trial, PRV was injected intramuscularly to induce changes. The farmed fish was gradually infected with PRV. Red focal changes occurred throughout the observation period with a low prevalence regardless of PRV status. Melanized changes were highly diverse and their prevalence increased during the trial. Changes of low macroscopic grade and histological category were more prevalent in PRV-negative fish. Diffuse granulomatous melanized changes only occurred after PRV infection. No muscular changes were observed in the experimentally challenged fish. Our studies do not indicate that PRV infection causes red focal changes, but seems important in the development of granulomatous melanized changes.
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Affiliation(s)
- Håvard Bjørgen
- Institute of Basic Science and Aquatic Medicine, Faculty of Veterinary MedicineNorwegian University of Life SciencesOsloNorway
| | | | | | - Agnar Kvellestad
- Institute of Basic Science and Aquatic Medicine, Faculty of Veterinary MedicineNorwegian University of Life SciencesOsloNorway
| | - Dhamotharan Kannimuthu
- Institute of Food Safety and Infection Biology, Faculty of Veterinary MedicineNorwegian University of Life SciencesOsloNorway
| | - Espen Rimstad
- Institute of Food Safety and Infection Biology, Faculty of Veterinary MedicineNorwegian University of Life SciencesOsloNorway
| | - Erling Olaf Koppang
- Institute of Basic Science and Aquatic Medicine, Faculty of Veterinary MedicineNorwegian University of Life SciencesOsloNorway
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30
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Bjørgen H, Koppang EO, Gunnes G, Hordvik I, Moldal T, Kaldhusdal M, Dale OB. Ectopic epithelial cell clusters in salmonid intestine are associated with inflammation. J Fish Dis 2018; 41:1031-1040. [PMID: 29572978 DOI: 10.1111/jfd.12780] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Revised: 12/07/2017] [Accepted: 12/07/2017] [Indexed: 06/08/2023]
Abstract
An epizootic incidence of intestinal adenocarcinomas was reported in brood fish of Atlantic salmon (Salmo salar L.) in 2009. The condition was associated with a specific diet inducing enteritis and morphological changes. Here, two field trials of fish up to slaughter size were initiated. In Trial 1, two different feed recipes were used. Feed I was predominantly based on marine ingredients, whereas plant ingredients were limited to soy protein concentrate and wheat. Feed II was lower in fishmeal and without soya protein, which was substituted with plant proteins from other sources. In Trial 2, a commercial feed (Feed III) was included. No macroscopic tumours were observed in 300 fish (Trial 1). At the end of both trials, samples from five different segments of the gastrointestinal tract of a total of 39 fish were investigated with morphological methods. Here, we show the presence of ectopic proliferating epithelial cells only occurring in inflamed intestine and predominantly in the second segment of the mid-intestine. Presence of ectopic epithelial cells in submucosal inflammatory foci may indicate early stages in tumorigenesis, but other possibilities such as proliferative enteric disorders cannot be excluded. Together with inflammation, carcinogenesis should be a focus of investigation in future feed trials.
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Affiliation(s)
- H Bjørgen
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - E O Koppang
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - G Gunnes
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - I Hordvik
- Institute of Biology, University of Bergen, Bergen, Norway
| | - T Moldal
- Norwegian Veterinary Institute, Oslo, Norway
| | | | - O B Dale
- Norwegian Veterinary Institute, Oslo, Norway
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31
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Jarungsriapisit J, Moore LJ, Fiksdal IU, Bjørgen H, Tangerås A, Köllner B, Koppang EO, Patel S. Time after seawater transfer influences immune cell abundance and responses to SAV3 infection in Atlantic salmon. J Fish Dis 2018; 41:1269-1282. [PMID: 29790161 DOI: 10.1111/jfd.12820] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 04/07/2018] [Accepted: 04/08/2018] [Indexed: 06/08/2023]
Abstract
Pancreas disease (PD) caused by salmonid alphavirus (SAV) severely affects salmonid aquaculture during the seawater phase. To characterize immune cells in target tissues for SAV infection, heart, pancreas and pyloric caeca were analysed from two groups of fish adapted to seawater for 2 and 9 weeks. The sections were scored for the relative abundance of cells expressing MHC class II, IgM, CD3, CD8 or neutrophil/granulocyte markers using immuno-histochemical techniques. In general, necrosis of tissue was more severe in fish infected at 2 weeks post-seawater transfer (wpt) compared with those infected at 9 wpt. At 9 wpt, there were higher numbers of MHC II+ cells in heart, pancreas and pyloric caeca, IgM+ cells in heart and pancreas, and CD3+ cells in pancreas compared to those infected at 2 wpt. The majority of the immune cells infiltrating PD-affected tissues were MHC II+ and CD3+ cells suggesting that antigen-presenting cells and T lymphocytes are the main types of immune cells responding to SAV infection. All the investigated cell types were also observed in pyloric caeca of infected fish, suggesting that this tissue may play a role in the immune response to SAV.
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Affiliation(s)
| | - L J Moore
- Institute of Marine Research, Bergen, Norway
| | - I U Fiksdal
- Institute of Marine Research, Bergen, Norway
| | - H Bjørgen
- Section of Anatomy and Pathology, Veterinary Faculty, Institute of Basal Sciences and Aquatic Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | | | - B Köllner
- Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Immunology, Greifswald, Germany
| | - E O Koppang
- Section of Anatomy and Pathology, Veterinary Faculty, Institute of Basal Sciences and Aquatic Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - S Patel
- Institute of Marine Research, Bergen, Norway
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32
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Bjørgen H, Wessel Ø, Fjelldal PG, Hansen T, Sveier H, Sæbø HR, Enger KB, Monsen E, Kvellestad A, Rimstad E, Koppang EO. Piscine orthoreovirus (PRV) in red and melanised foci in white muscle of Atlantic salmon (Salmo salar). Vet Res 2015; 46:89. [PMID: 26346256 PMCID: PMC4562189 DOI: 10.1186/s13567-015-0244-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 08/17/2015] [Indexed: 11/10/2022] Open
Abstract
Melanised focal changes (black spots) are common findings in the white skeletal muscle of seawater-farmed Atlantic salmon (Salmo salar). Fillets with melanised focal changes are considered as lower quality and cause large economic losses. It has been suggested that red focal changes (red spots) precede the melanised focal changes. In the present work, we examined different populations of captive and wild salmon for the occurrence of both types of changes, which were investigated for the presence of different viruses by immunohistochemistry and RT-qPCR. The occurrence of red or melanised foci varied significantly between the populations, from none in wild fish control group, low prevalence of small foci in fish kept in in-house tanks, to high prevalence of large foci in farm-raised salmon. Large amounts of Piscine orthoreovirus (PRV) antigen were detected in all foci. No other viruses were detected. Red focal changes contained significantly higher levels of PRV RNA than apparently non-affected areas in white muscle of the same individuals. Some changes displayed a transient form between a red and melanised pathotype, indicating a progression from an acute to a chronic manifestation. We conclude that PRV is associated with the focal pathological changes in the white muscle of farmed Atlantic salmon and is a premise for the development of focal melanised changes.
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Affiliation(s)
- Håvard Bjørgen
- Institute of Basic Science and Aquatic Medicine, School of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
| | - Øystein Wessel
- Institute of Food Safety and Infection Biology, School of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
| | | | - Tom Hansen
- Matre Research Station, Institute of Marine Research, Matre, Norway.
| | | | - Håkon Rydland Sæbø
- Department Brandasund and Rex Star, Lerøy Sjøtroll AS, Skjervøy, Norway.
| | | | | | - Agnar Kvellestad
- Institute of Basic Science and Aquatic Medicine, School of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
| | - Espen Rimstad
- Institute of Food Safety and Infection Biology, School of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
| | - Erling Olaf Koppang
- Institute of Basic Science and Aquatic Medicine, School of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
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33
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Dalum AS, Austbø L, Bjørgen H, Skjødt K, Hordvik I, Hansen T, Fjelldal PG, Press CM, Griffiths DJ, Koppang EO. The interbranchial lymphoid tissue of Atlantic Salmon ( Salmo salarL) extends as a diffuse mucosal lymphoid tissue throughout the trailing edge of the gill filament. J Morphol 2015. [DOI: 10.1002/jmor.20431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Alf S. Dalum
- Faculty of Veterinary Medicine and Biosciences; Department of Basic Sciences and Aquatic Medicine; Norwegian University of Life Sciences; Oslo Norway
| | - Lars Austbø
- Faculty of Veterinary Medicine and Biosciences; Department of Basic Sciences and Aquatic Medicine; Norwegian University of Life Sciences; Oslo Norway
| | - Håvard Bjørgen
- Faculty of Veterinary Medicine and Biosciences; Department of Basic Sciences and Aquatic Medicine; Norwegian University of Life Sciences; Oslo Norway
| | - Karsten Skjødt
- Faculty of Health Science; Department of Cancer and Inflammation Research; Institute of Molecular Medicine, University of Southern Denmark; Odense Denmark
| | - Ivar Hordvik
- Faculty of Mathematics and Natural Sciences; Department of Biology; University of Bergen; Bergen Norway
| | - Tom Hansen
- Matre Research Station; Institute of Marine Research; Matre Norway
| | - Per G. Fjelldal
- Matre Research Station; Institute of Marine Research; Matre Norway
| | - Charles McL Press
- Faculty of Veterinary Medicine and Biosciences; Department of Basic Sciences and Aquatic Medicine; Norwegian University of Life Sciences; Oslo Norway
| | - David J. Griffiths
- Faculty of Veterinary Medicine and Biosciences; Department of Basic Sciences and Aquatic Medicine; Norwegian University of Life Sciences; Oslo Norway
| | - Erling O. Koppang
- Faculty of Veterinary Medicine and Biosciences; Department of Basic Sciences and Aquatic Medicine; Norwegian University of Life Sciences; Oslo Norway
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34
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Dalum AS, Austbø L, Bjørgen H, Skjødt K, Hordvik I, Hansen T, Fjelldal PG, Press CM, Griffiths DJ, Koppang EO. The interbranchial lymphoid tissue of Atlantic Salmon (Salmo salarL) extends as a diffuse mucosal lymphoid tissue throughout the trailing edge of the gill filament. J Morphol 2015; 276:1075-88. [DOI: 10.1002/jmor.20403] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 04/10/2015] [Accepted: 04/29/2015] [Indexed: 12/14/2022]
Affiliation(s)
- Alf S. Dalum
- Faculty of Veterinary Medicine and Biosciences; Department of Basic Sciences and Aquatic Medicine; Norwegian University of Life Sciences; Oslo Norway
| | - Lars Austbø
- Faculty of Veterinary Medicine and Biosciences; Department of Basic Sciences and Aquatic Medicine; Norwegian University of Life Sciences; Oslo Norway
| | - Håvard Bjørgen
- Faculty of Veterinary Medicine and Biosciences; Department of Basic Sciences and Aquatic Medicine; Norwegian University of Life Sciences; Oslo Norway
| | - Karsten Skjødt
- Faculty of Health Science; Department of Cancer and Inflammation Research; Institute of Molecular Medicine, University of Southern Denmark; Odense Denmark
| | - Ivar Hordvik
- Faculty of Mathematics and Natural Sciences; Department of Biology; University of Bergen; Bergen Norway
| | - Tom Hansen
- Matre Research Station; Institute of Marine Research; Matre Norway
| | - Per G. Fjelldal
- Matre Research Station; Institute of Marine Research; Matre Norway
| | - Charles McL Press
- Faculty of Veterinary Medicine and Biosciences; Department of Basic Sciences and Aquatic Medicine; Norwegian University of Life Sciences; Oslo Norway
| | - David J. Griffiths
- Faculty of Veterinary Medicine and Biosciences; Department of Basic Sciences and Aquatic Medicine; Norwegian University of Life Sciences; Oslo Norway
| | - Erling O. Koppang
- Faculty of Veterinary Medicine and Biosciences; Department of Basic Sciences and Aquatic Medicine; Norwegian University of Life Sciences; Oslo Norway
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35
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Bjørgen H, Koppang E, Kaldhusdal M, Moldal T, Dale OB. Generalised inflammation with CD3ε and MHC class II positive cells and dislocated epithelial cells in the mid-intestine in farmed Atlantic salmon ( Salmo salar L.) (VET2P.1132). The Journal of Immunology 2015. [DOI: 10.4049/jimmunol.194.supp.147.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Farmed Atlantic salmon is routinely fed with pellets containing vegetable ingredients. Certain plant proteins may induce an inflammatory environment in the intestinal tract of fish, and carcinogenesis has also been noted. The pathogenesis is similar to that of inflammatory bowel disease (IBD)-related cancer in humans. A feed trial was designed to stimulate to inflammation in experimental fish. Three separate groups were subjected to feeding regimes where two of the groups received feeds containing different plant ingredients (A and B), and a third group received a diet based on marine ingredients. Immunofluorescence targeting CD3ε and MHC class II were used to study the inflammation. Epithelial cells were identified with haematoxylin & eosin staining and immunohistochemistry. A pan cytokeratin antibody was used to identify epithelial cells, and a proliferating cell nuclear antigen (PCNA) antibody was used to mark proliferating cells. Periodic acid Shiff (PAS) staining was used to detect mucins. Immunofluorescence revealed severe generalised inflammation and various amounts of dislocated epithelial cells in the fish receiving experimental diet B. The fish given experimental diet A was less affected. The control group was unaffected. There was a clear association between inflammation and dislocated epithelial cells. The inflammatory response was dominated with T-cell infiltrates in a similar fashion as that seen in IBD-affected human intestine.
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