Characterization and functional analysis of goldfish (Carassius auratus L.) interleukin-10.

This is the first report of comprehensive functional analysis of an interleukin-10 in bony fish. Quantitative expression analysis of goldfish IL-10 revealed the greatest mRNA levels in the spleen tissues, peripheral blood leukocytes and granulocytes. The stimulation of cells with recombinant goldfish (rg) TNFα2 significantly reduced IL-10 mRNA levels in granulocytes and monocytes of the goldfish. To functionally assess the goldfish IL-10, we generated a recombinant form of the molecule (rgIL-10). The rgIL-10 substantially reduced the expression of TNFα1, TNFα2, IL-1ß1, IL-10, CXCL-8, and NADPH oxidase component, p47(phox) in monocytes activated with heat-killed Aeromonas salmonicida and reduced the expression of IFNγ in A. salmonicida-activated splenocytes. Pre-treatment of monocytes with rgIL-10 resulted in substantial reduction of the ROI response of the A. salmonicida or rgIFNγ-primed monocytes. The rgIL-10 bound to goldfish monocytes and induced phosphorylation and nuclear translocation of Stat3. The rgIL-10 also induced rapid and robust increase in the mRNA levels of the goldfish monocyte SOCS-3. Our results indicate that the function of IL-10 is highly conserved through evolution.

Hymenolepis diminuta (Cestoda) induces changes in expression of select genes of Tribolium confusum (Coleoptera).

The flour beetle Tribolium confusum is a common experimental intermediate host for the tapeworm Hymenolepis diminuta, but while many aspects of their host-parasite interactions have been determined to have genetic basis, the genes involved have not been identified. In this paper, we report on the expression of several predicted metabolic and defense-related genes using quantitative polymerase chain reaction 2 weeks after initial infection of the beetle. The expression of heat shock protein 68, a predicted sugar transporter, a pheromone binding protein, and endoglin were up-regulated in infected beetles. The expression of thaumatin-like protein and prophenoloxidase 2/3 was down-regulated in infected beetles, while the mRNA levels of Toll-like receptor 3, Toll-like receptor 4, and lysozyme 4 were not affected by infection with H. diminuta.

Macrophage colony stimulating factor (CSF-1) is a central growth factor of goldfish macrophages.

We recently characterized macrophage colony stimulating factor (CSF-1) of fish (the goldfish). Here, we report for the first time that goldfish CSF-1 acts through the CSF-1 receptor by showing loss of CSF-1 function in CSF-1R knockdown monocytes using RNAi, and demonstrate that goldfish CSF-1 administration in vivo increases the amount of circulating monocytes in blood. We also show that conditioned supernatants from goldfish fibroblast cultures induced the proliferation of goldfish monocytes indicating that, like in mammals, teleost fibroblasts are an important producer of CSF-1. The continuous addition of recombinant CSF-1 to primary goldfish macrophage cultures stabilized and extended their longevity and resulted in a long-term culture of functional macrophages capable of mounting a potent nitric oxide response upon activation with goldfish recombinant TNF-alpha.

Development of macrophages of cyprinid fish.

The innate immune responses of early vertebrates, such as bony fishes, play a central role in host defence against infectious diseases and one of the most important effector cells of innate immunity are macrophages. In order for macrophages to be effective in host defence they must be present at all times in the tissues of their host and importantly, the host must be capable of rapidly increasing macrophage numbers during times of need. Hematopoiesis is a process of formation and development of mature blood cells, including macrophages. Hematopoiesis is controlled by soluble factors known as cytokines, that influence changes in transcription factors within the target cells, resulting in cell fate changes and the final development of specific effector cells. The processes involved in macrophage development have been largely derived from mammalian model organisms. However, recent advancements have been made in the understanding of macrophage development in bony fish, a group of organisms that rely heavily on their innate immune defences. Our understanding of the growth factors involved in teleost macrophage development, as well as the receptors and regulatory mechanisms in place to control them has increased substantially. Furthermore, model organisms such as the zebrafish have emerged as important instruments in furthering our understanding of the transcriptional control of cell development in fish as well as in mammals. This review highlights the recent advancements in our understanding of teleost macrophage development. We focused on the growth factors identified to be important in the regulation of macrophage development from a progenitor cell into a functional macrophage and discuss the important transcription factors that have been identified to function in teleost hematopoiesis. We also describe the findings of in vivo studies that have reinforced observations made in vitro and have greatly improved the relevance and importance of using teleost fish as model organisms for studying developmental processes.