Project description:Background: Commercial Atlantic salmon is fed diets with high fat levels to promote fast and cost-eﬀective growth. To avoid negative impact of obesity, food additives that stimulate fat metabolism and immune function are of high interest. TTA, tetradecylthioacetic acid, is a synthetic fatty acid that stimulates mitochondrial β -oxidation most likely by activation of peroxysome proliferator-activated receptors (PPARs). PPARs are important transcription factors regulating multiple functions including fat metabolism and immune responses. Atlantic salmon experiments have shown that TTA supplemented diets signiﬁcantly reduce mortality during natural outbreaks of viral diseases, suggesting a modulatory role of the immune system. Results: To gain new insights into TTA eﬀects on the Atlantic salmon immune system, a factorial, high-throughput microarray experiment was conducted using a 44K oligo nucleotide salmon microarray SIQ2.0 and the Atlantic salmon macrophage-like cell line ASK. The experiment was used to determine the transcriptional eﬀects of TTA, the eﬀects of TTA in poly(I:C) elicited cells and the eﬀects of pretreating the cells with TTA. The expression patterns revealed that a large proportion of genes regulated by TTA were related to lipid metabolism and increased mitochondrial β -oxidation. In addition we found that for a subset of genes TTA antagonized the transcriptional eﬀects of poly(I:C). This, together with the results from qRT-PCR showing an increased transcription of anti-inﬂammatory IL10 by TTA, indicates anti-inﬂammatory eﬀects. Conclusions: We demonstrate that TTA has signiﬁcant eﬀects on macrophage-like salmon cells that are challenged by the artiﬁcial dsRNA poly(I:C). The immune stimulatory eﬀect of TTA in macrophages involves increased lipid metabolism and suppressed inﬂammatory status. Thus, suggesting that TTA directs the macrophage-like cells towards alternative, anti-inﬂammatory, activation. This has positive implications for TTA as a feed additive. Factorial designed experiment: factor pretreatment = 2 levels (Control, TTA); factor treatment = 4 levels (Control, TTA, polyIC, TTA+polyIC). Experiment was performed with 2 biological replicates (different passages). 1 array hybridization failed and was excluded from the dataset. Therefore total number of arrays =15

Project description:Background: Commercial Atlantic salmon is fed diets with high fat levels to promote fast and cost-eﬀective growth. To avoid negative impact of obesity, food additives that stimulate fat metabolism and immune function are of high interest. TTA, tetradecylthioacetic acid, is a synthetic fatty acid that stimulates mitochondrial β -oxidation most likely by activation of peroxysome proliferator-activated receptors (PPARs). PPARs are important transcription factors regulating multiple functions including fat metabolism and immune responses. Atlantic salmon experiments have shown that TTA supplemented diets signiﬁcantly reduce mortality during natural outbreaks of viral diseases, suggesting a modulatory role of the immune system. Results: To gain new insights into TTA eﬀects on the Atlantic salmon immune system, a factorial, high-throughput microarray experiment was conducted using a 44K oligo nucleotide salmon microarray SIQ2.0 and the Atlantic salmon macrophage-like cell line ASK. The experiment was used to determine the transcriptional eﬀects of TTA, the eﬀects of TTA in poly(I:C) elicited cells and the eﬀects of pretreating the cells with TTA. The expression patterns revealed that a large proportion of genes regulated by TTA were related to lipid metabolism and increased mitochondrial β -oxidation. In addition we found that for a subset of genes TTA antagonized the transcriptional eﬀects of poly(I:C). This, together with the results from qRT-PCR showing an increased transcription of anti-inﬂammatory IL10 by TTA, indicates anti-inﬂammatory eﬀects. Conclusions: We demonstrate that TTA has signiﬁcant eﬀects on macrophage-like salmon cells that are challenged by the artiﬁcial dsRNA poly(I:C). The immune stimulatory eﬀect of TTA in macrophages involves increased lipid metabolism and suppressed inﬂammatory status. Thus, suggesting that TTA directs the macrophage-like cells towards alternative, anti-inﬂammatory, activation. This has positive implications for TTA as a feed additive.

Project description:Although drug induced steatosis represents a mild type of hepatotoxicity, it can progress into more severe non-alcoholic steatohepatitis. Current models used for safety assessment in drug development and chemical risk assessment do not accurately predict steatosis in humans. Therefore, new models need to be developed to screen compounds for steatogenic properties. We have studied the usefulness of mouse precision-cut liver slices (PCLS) as an alternative to animal testing to gain more insight into the mechanisms involved in the steatogenesis. To this end, PCLS were incubated 24h with the model steatogenic compounds, amiodarone (AMI), valproic acid (VA), and tetracycline (TET). Transcriptome analysis using DNA microarrays was used to identify genes and processes affected by these compounds. AMI and VA upregulated lipid metabolism, whereas processes associated with extracellular matrix remodelling and inflammation were downregulated. TET downregulated mitochondrial functions, lipid metabolism, and fibrosis. From the transcriptomics data it was hypothesized that all 3 compounds affect peroxisome proliferator activated-receptor (PPAR) signalling. Application of PPAR reporter assays classified AMI and VA as PPARγ and triple PPARα/ (β/δ)/γ agonist, respectively, whereas TET had no effect on any of the PPARs. Some of the differentially expressed genes were considered as potential candidate biomarkers to identify PPAR agonists (i.e. AMI and VA) or compounds impairing mitochondrial functions (i.e. TET). Finally, comparison of our findings with publicly available transcriptomics data showed that a number of processes altered in the mouse PCLS was also affected in mouse livers and human primary hepatocytes exposed to known PPAR agonists. Thus mouse PCLS are a valuable model to identify mechanisms of action of compounds altering lipid metabolism. Two sets of candidate biomarkers could be used to screen compounds interfering with lipid metabolism by different mechanisms. Cholestatic compounds exposures

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Effects on the lipid metabolism of Atlantic cod (Gadus morhua) after in vivo exposure with Ppar agonists

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