Rainbow Trout Head Kidney Research Articles

In vitro activation of rainbow trout macrophages stimulates inhibition of Renibacterium salmoninarum growth concomitant with augmented generation of respiratory burst products

DAO Diseases of Aquatic Organisms Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials DAO 25:175-183 (1996) - doi:10.3354/dao025175 In vitro activation of rainbow trout macrophages stimulates inhibition of Renibacterium salmoninarum growth concomitant with augmented generation of respiratory burst products Hardie LJ, Ellis AE, Secombes CJ Rainbow trout head kidney macrophages pretreated for 48 h with a supernatant which contained macrophage activating factor (MAF) obtained from Concanavalin A/phorbol myristate acetate stimulated rainbow trout leucocytes express an enhanced ability to inhibit Renibacterium salmoninarum growth in vitro compared with untreated controls. Enhanced 'killing' capacity of these macrophages was detectable after 24 h exposure to R. salmoninarum in vitro. Addition of NG-methyl-L-arginine in vitro did not diminish bacterial growth inhibition by MAF-activated macrophages, suggesting that nitric oxide radicals were not involved in this event. However, MAF-treated macrophages expressed enhanced respiratory burst activity compared with control macrophages after a 3 d exposure to R. salmoninarum in vitro. In addition, it was demonstrated that R. salmoninarum was susceptible to hydrogen peroxide (H2O2) in vitro using a cell-free assay. Introduction of catalase to the in vitro macrophage assay abrogated the 'killing' activity, suggesting that H2O2 release from activated macrophages was involved in the inhibition of R. salmoninarum growth. The results are discussed in relation to other intracellular pathogens and the possible importance of cell-mediated immunity for protection against bacterial kidney disease. Renibacterium salmoninarum . Macrophage activation . Respiratory burst . Growth inhibition Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in DAO Vol. 25, No. 3. Publication date: June 06, 1996 Print ISSN:0177-5103; Online ISSN:1616-1580 Copyright © 1996 Inter-Research.

Cytochrome P450c21 activity in rainbow trout head kidney. Effects of handling stress, ACTH and dexamethasone

Cytochrome P450c21 activity in rainbow trout head kidney. Effects of handling stress, ACTH and dexamethasone

The effect of eicosanoids on rainbow trout, Oncorhynchus mykiss, leucocyte proliferation

Proliferation of rainbow trout head kidney leucocytes in response to the mitogen phytohaemagglutinin-P (PHA-P) was modulated in the presence of inhibitors of eicosanoid synthesis and by exogenous eicosanoids. The presence of indomethacin, a cyclooxygenase inhibitor, resulted in a stimulatory effect, whereas the presence of nordihydroguiaretic acid, a lipoxygenase inhibitor, resulted in an inhibitory effect on mitogenicity. The addition of prostaglandins and lipoxins was also found to be inhibitory, whilst the addition of leukotrienes was stimulatory. Some class/series effects of the eicosanoids were also apparent. Prostaglandin E2 was a more potent inhibitor than prostaglandin E3, and proliferation was more sensitive to the effects of leukotriene B4 than to leukotriene B5. Whilst PHA-P was able to directly induce the release of prostaglandins from head kidney leucocytes, it did not induce the release of lipoxygenase products.

Receptor-mediated endocytosis and phagocytosis by rainbow trout head kidney sinusoidal cells

Endocytosis by rainbow trout head kidney sinusoidal cells was studied following intravenous administration of various ligands. Immunohistochemistry was used to demonstrate that endothelial cells took up the soluble ligands ovalbumin and dinitrophenylated human serum albumin (DNP 33HSA). Ovalbumin and DNP 33HSA are endocytosed via the mannose- and the scavenger receptor, respectively. Sinusoidal macrophages took up DNP 33HSA but only occasionally ovalbumin. The particulate ligand, colloidal human serum albumin (cHSA) (0·2-1μm) was taken up by both endothelial cells and sinusoidal macrophages. Endothelial cells were estimated to account for at least 15% of uptake of intravenously injected 125 I-tyramine cellobiose-labelled cHSA ( 125I-TC-cHSA) by head kidney cells. Uptake of 125I-TC-cHSA could be demonstrated in cultured head kidney macrophages. Intracellular transport of in vivo internalized 125I-TC-cHSA to lysosomal compartments occurred at a slower rate compared to ligands endocytosed via the mannose- and scavenger-receptors. Electron microscopic studies of head kidney endothelium that had taken up colloidal carbon, revealed that sinusoidal endothelial cells possess the ultra-structural apparatus characteristic for cells active in endocytosis of blood-borne ligands; namely well defined coated pits along the luminal plasma membrane, numerous intracellular vesicles and large, lysosome-like dense bodies. Thus, the results of this study suggest that both head kidney endothelial cells and sinusoidal macrophages are important 'scavenger' cells in rainbow trout.

Long-term liquid culture of haematopoietic precursor cells from the head kidney and spleen of the rainbow trout (Oncorhynchus mykiss)

Cells from the spleen and head kidney of rainbow trout (Oncorhynchus mykiss) were cultured in vitro. The cells were held in culture for more than three months. Spleen cells lived only a few days if cultured between October and May, but long-term cultures were possible in late spring and summer. This variation is assumed to be due to seasonal variations in the content of precursor cells.

The role of reactive oxygen species in the killing of the bacterial fish pathogen Aeromonas salmonicida by rainbow trout macrophages

The role of reactive oxygen species (ROS) in the killing of the bacterial pathogen Aeromonas salmonicida by in vitro cultured rainbow trout (Oncorhynchus mykiss) head kidney macrophages has been investigated. Using a microtitre plate bactericidal assay the respiratory burst pathway responsible for ROS generation was inhibited completely using the NADPH oxidase inhibitor trifluoperazine and partially by the use of ROS scavengers (formate and/or mannitol) and the antioxidative enzymes SOD and/or catalase. Increased bacterial survival of an avirulent strain (MT004) in the presence of trifluoperazine, catalase and formate confirmed that ROS such as hydrogen peroxide and hydroxyl radicals were indeed an important killing agent. This was further confirmed using sodium nitroprusside and aminotriazole, inhibitors of SOD and catalase respectively. The presence of aminotriazole caused a significantly increased bactericidal activity against a virulent strain (MT423) normally resistant to killing by cultured resident rainbow trout head kidney macrophages.

In vitro stimulation of salmonid leucocytes with mitogens and with Aeromonas salmonicida

Leucocytes from peripheral blood (PBL), spleen and head kidney of Atlantic salmon ( Salmo salar ) and rainbow trout ( Oncorhynchus mykiss ) responded well when stimulated with lipopolysaccharide from Escherichia coli and phytohaemagglutinin (PHA). Thymocytes responded to PHA only. PBL from Atlantic salmon vaccinated against furunculosis showed significantly higher responses as compared to non-vaccinated fish when stimulated with an antigen preparation of whole cells of Aeromonas salmonicida . In leucocyte cultures from rainbow trout vaccinated against furunculosis, specific antibodies to A. salmonicida were produced in vitro . None or very low antibody levels were detected in cultures from non-immunised fish during the first 7 days in culture. After 9 days, a primary antibody response to A. salmonicida could, however, be detected in these cultures. Good correlation ( r =0·88) between antibody production by blood leucocytes and splenocytes was seen.

Rainbow trout [ Oncorhynchus mykiss (Walbaum, 1792)] leucocyte interactions with metacestode stages of Diphyllobothrium dendriticum (Nitzsch, 1824), (Cestoda, Pseudophyllidea)

Procercoids of Diphyllobothrium dendriticum were incubated for 5 or 24 h with rainbow trout head kidney leucocyte suspension in vitro , in the absence or presence of complete and/or incomplete (heat inactivated) normal or specific immune serum. Neutrophils and macrophages were the predominant leucocytes that were found to adhere to the procercoid tegument, although a third unidentified leucocyte type was also seen. Leucocyte adherence was considerably increased by the presence of immune serum, indicating a possible interaction between the non-specific and specific immune response in the host inflammatory reaction to this parasite. Indeed, it was only in the presence of immune serum that damage to the procercoid tegument occurred. Production of both hydrogen peroxide and superoxide anion from macrophages was induced by antigen extracts from plerocercoids of D. dendriticum , prepared either by freezing and thawing specimens or by culturing live plerocercoids in vitro to obtain a conditioned medium. The possibility that reactive oxygen species contribute to the damage observed in the adherence assays is discussed.

Localization of cytochrome P-450 in the head and trunk kidney of rainbow trout ( Salmo gairdneri)

Mature, untreated rainbow trout display a marked sex difference in the level and activity of the P-450-dependent mixed-function oxidase system with males demonstrating higher levels than females. This difference is accentuated in the trunk kidney, is specific for endogenous substrates such as lauric acid and sex steroids, and is correlated with greater levels of the constitutive cytochrome P-450 isozyme, LM 2. Using an immunohistochemical technique, the cellular localization of P-450 LM 2 and P-450 LM 4b, the major β-naphthoflavone inducible isozyme, in the head and trunk kidney of male, female, and juvenile trout has been demonstrated. Immunostaining for P-450 LM 2 was observed in the cytoplasm of cells in the second portion (P 2) of the proximal tubules of both male and female trout. In male fish, staining appeared to be more intense and involved most of the P 2 segments in a tissue section. In female fish, P 2 staining was moderate and involved fewer segments. Low staining intensity for P-450 LM 4b was observed in the cytoplasm of cells both in the first portion of the proximal tubules and in P 2 of male and female fish. Sexual dimorphism was not apparent. The finding of greater amounts of P-450 LM 2 in males and low levels of P-450 LM 4b in untreated male and female trout confirms previous biochemical studies. Localization of P-450 isozymes in the proximal tubules is consistent with findings in mammalian species. Moderate immunostaining by anti- P-450 LM 4b IgG also was observed in the interrenal cells of the head kidney of male, female, and juvenile trout.

Lymphokine-release from rainbow trout leucocytes stimulated with concanavalin A. Effects upon macrophage spreading and adherence

Rainbow trout blood and head kidney leucocytes were stimulated with the mitogen ConA to release a factor(s) that increased macrophage spreading and adherence. ConA present in control cultures was also shown to have this effect and so removal of ConA was essential to investigate the action of potential lymphokines. Either a 3h pulse with ConA or absorption of supernatants with Sephadex G10 was found to successfully remove activity from control supernatants whilst having no effect upon the lymphokine-containing supernatants.

Influence of sex steroids on the catecholamine biosynthesis in chromaffin tissue from rainbow trout, Salmo gairdneri

The in vitro activities of dopamine-β-hydroxylase (DBH) and phenylethanolamine- N-methyl transferase (PNMT) were determined in the chromaffin tissue (head kidney) of sex steroid-treated rainbow trout, Salmo gairdneri. In addition, the DBH and PNMT activities were measured in fish at different sexual states. Steroid treatment increased the wet weight of the head kidney, while both DBH and PNMT activities decreased. Although no sex difference in the enzyme activities was detected, a possible correlation between DBH and PNMT activities and increased GSI values was indicated. The presented data suggest that changes in sex steroids during development may affect the catecholamine synthesis in the chromaffin tissue in S. gairdneri.