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Gene expression profiling of liver from dairy cows treated intra-mammary with lipopolysaccharide.

ABSTRACT: BACKGROUND: Liver plays a profound role in the acute phase response (APR) observed in the early phase of acute bovine mastitis caused by Escherichia coli (E. coli). To gain an insight into the genes and pathways involved in hepatic APR of dairy cows we performed a global gene expression analysis of liver tissue sampled at different time points before and after intra-mammary (IM) exposure to E. coli lipopolysaccharide (LPS) treatment. RESULTS: Approximately 20% target transcripts were differentially expressed and eight co-expression clusters were identified. Each cluster had a unique time-dependent expression profile and consisted of genes involved in different biological processes. Our findings suggest that APR in the liver is triggered by the activation of signaling pathways that are involved with common and hepatic-specific transcription factors and pro-inflammatory cytokines. These mediators in turn stimulated or repressed the expression of genes encoding acute phase proteins (APP), collectins, complement components, chemokines, cell adhesion molecules and key metabolic enzymes during the APR. Hormones, anti-inflammatory and other hypothalamus-pituitary-adrenal axis (HPAA) linked mediators also seemed to participate in APR. CONCLUSION: Performing global gene expression analysis on liver tissue from IM LPS treated cows verified that the liver plays a major role in the APR of E. coli mastitis, and that the bovine hepatic APR follows the same pattern as other mammals when they are challenged with LPS. Our work presents the first insight into the dynamic changes in gene expression in the liver that influences the induction, kinetics and clinical outcome of the APR in dairy cows.

SUBMITTER: Jiang L

PROVIDER: S-EPMC2576255 | biostudies-literature | 2008

REPOSITORIES: biostudies-literature

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Gene expression profiling of liver from dairy cows treated intra-mammary with lipopolysaccharide.

Jiang Li L Sørensen Peter P Røntved Christine C Vels Lotte L Ingvartsen Klaus L KL

BMC genomics 20080924

<h4>Background</h4>Liver plays a profound role in the acute phase response (APR) observed in the early phase of acute bovine mastitis caused by Escherichia coli (E. coli). To gain an insight into the genes and pathways involved in hepatic APR of dairy cows we performed a global gene expression analysis of liver tissue sampled at different time points before and after intra-mammary (IM) exposure to E. coli lipopolysaccharide (LPS) treatment.<h4>Results</h4>Approximately 20% target transcripts wer ...[more]

PMID: 18816405

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Project description:The study investigated the acute and simultaneous response of the mammary and liver transcriptome to an intra-mammary lipopolysaccharide (LPS) challenge in early-lactating cows, and its consequences on metabolic biomarkers and liver composition. At 7 days of lactation, 7 cows served as controls (CTR) and 7 cows (LPS) received an intra-mammary E. coli LPS challenge. The mammary and liver tissues were sampled at 2.5 h from challenge for transcriptomic profiling. Liver composition was evaluated at 2.5 h and 7 d after challenge and blood biomarkers were analized at -2, 3, 7 and 14 d from challenge. In mammary tissue, the LPS challenge resulted in 189 differentially expressed gene (DEG), with 20 downregulated and 169 upregulated, while in the liver were found 107 DEG with 42 downregulated and 65 upregulated in LPS vs CTR. In the udder, the Dynamic Impact Approach (DIA) highlighted the activation of NOD-like receptor signaling, Toll-like receptor signaling, RIG-I-like receptor signaling and Apoptosis pathways, while in the liver were inhibited the Fatty acid elongation in mitochondria and activated the p53 signaling pathway. The LPS induced the alteration of liver lipid metabolism (rise of total lipid and triglyceride concentration), a systemic inflammation (rise of blood ceruloplasmin and bilirubin) and an increase of body fat mobilization. In cows subjected to intra-mammary LPS, the mammary gland responds activating mechanisms of pathogen recognition. In the liver the response likely depends by mediators coming from udder and affects the liver functionality and mainly the fatty acid metabolism. Fourteen Holstein cows entering their second or greater lactation were used. Cows were housed in a ventilated tie-stall barn and were fed a common lactation diet (Net energy of lactation = 1.69 Mcal/kg DM) as a total mixed ration once daily (0600 h) and milked twice daily (0400 and 1600 h). A bovine oligonucleotide (70-mers) microarray with >13,000 annotated sequences developed at the University of Illinois, was used for transcript profiling. Details on the development, annotation, and use of this microarray have been reported previously by Loor et al., 2007 (http://physiolgenomics.physiology.org/content/32/1/105.abstract). Methods for microarray hybridization and scanning were as reported by Loor et al. (2007). Briefly, slides were hydrated, dried, and placed in a UV Stratalinker 1800 (Stratagene, La Joya, CA) for ~5 min. Slides were washed with 0.2% SDS solution, rinsed with MilliQ (Millipore) H2O, and placed in warm prehybridization soln for 45 min at 42 C. The same amount of Cy3- or Cy5-labelled cDNA from mammary or liver and a reference standard RNA pool (made of different bovine tissues) were co-hybridized using a dye-swap design (i.e., two microarrays per sample). Slides were incubated for 48 h at 45 C prior to scanning. Criteria for evaluation of slide quality included: identification of number of spots with a minimum median signal intensity of 3 SD above background; keeping slides with a minimum of 20,000 spots with minimum median signal intensity of 3 SD above background in both Cy3 and Cy5 channels; and keeping slides with a minimum mean intensity of 400 relative fluorescent units in both Cy3 and Cy5 channels across the entire slide. Data from a total of 112 microarrays were normalized for dye and microarray effects (i.e., Lowess normalization and microarray centering) and used for statistical analysis. Data were analyzed using the Proc MIXED procedure of SAS (SAS, SAS Inst. Inc., Cary, NC). Fixed effects were treatment (LPS challenge, control (no infsuion)) and dye. Random effects included cow and microarray. Raw P values were adjusted using Benjamini and HochbergM-bM-^@M-^Ys false discovery rate (FDR). Differences in relative expression due to treatment were considered significant at an FDR-adjusted P < 0.05. For a more stringent characterization between the two treatments, a 1.5-fold difference in mRNA expression was set as threshold among differentially expressed genes.

Dataset Information

Gene expression profiling of liver from dairy cows treated intra-mammary with lipopolysaccharide.

Publications

Gene expression profiling of liver from dairy cows treated intra-mammary with lipopolysaccharide.

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