CpGs Induce Differentiation of Atlantic Salmon Mononuclear Phagocytes Into Cells With Dendritic Morphology and a Proinflammatory Transcriptional Profile but an Exhausted Allostimulatory Activity

• Published in: Frontiers in Immunology
• Main Authors: Iliev, Dimitar Borisov, Lagos, Leidy, Thim, Hanna Leena, Jørgensen, Sven Martin, Krasnov, Aleksei, Jørgensen, Jorunn B
• Format: Article in Journal/Newspaper
• Language: English
• Published: Frontiers Media 2019
• Subjects: VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920; VDP::Landbruks- og Fiskerifag: 900::Fiskerifag: 920; mononuclear phagocytes; antigen-presenting cells; dendritic cells; CpG oligodeoxynucleotides; Atlantic salmon; teleosts
• Online Access: https://hdl.handle.net/10037/15107; https://doi.org/10.3389/fimmu.2019.00378

The following article, Iliev, D.B., Lagos, L., Thim, H.L., Jørgensen, S.M., Krasnov, A. & Jørgensen, J.B. (2019). CpGs Induce Differentiation of Atlantic Salmon Mononuclear Phagocytes Into Cells With Dendritic Morphology and a Proinflammatory Transcriptional Profile but an Exhausted Allostimulatory Activity. Frontiers in Immunology , can be accessed at https://doi.org/10.3389/fimmu.2019.00378 . Due to their ability to present foreign antigens and prime naïve T cells, macrophages, and dendritic cells (DCs) are referred to as professional antigen-presenting cells (APCs). Although activated macrophages may function as APCs, these cells are particularly effective at directly engaging pathogens through phagocytosis, and production of antimicrobial compounds. On the other hand, DCs possess superb antigen-presenting and costimulatory capacity and they are essential for commencement and regulation of adaptive immune responses. In in vitro models, development of mature mammalian DCs from monocytes requires sequential exposure to growth factors (including GM-CSF and IL-4) and proinflammatory stimuli such as toll-like receptor (TLR) ligands. Currently, except for IL-4/13, neither orthologs nor functional analogs of the growth factors which are essential for the differentiation of mammalian DCs (including GM-CSF and FLT3) have been identified in teleosts and data about differentiation of piscine APCs is scant. In the present study, primary salmon mononuclear phagocytes (MPs) stimulated in vitro for 5–7 days with a B-class CpG oligodeoxynucleotides (ODN 2006PS) underwent morphological differentiation and developed “dendritic” morphology, characterized by long, branching pseudopodia. Transcriptional profiling showed that these cells expressed high levels of proinflammatory mediators characteristic for M1 polarized MPs. However, the cells treated with CpGs for 7 days downregulated their surface MHCII molecules as well as their capacity to endocytose ovalbumin and exhibited attenuated allostimulatory activity. This ...