title: Characterization of ovine hepatic gene expression profiles in response to Escherichia coli lipopolysaccharide using a bovine cDNA microarray.
abstract: BACKGROUND
  During systemic gram-negative bacterial infections, lipopolysaccharide (LPS) ligation to the hepatic Toll-like receptor-4 complex induces the production of hepatic acute phase proteins that are involved in the host response to infection and limit the associated inflammatory process. Identifying the genes that regulate this hepatic response to LPS in ruminants may provide insight into the pathogenesis of bacterial diseases and eventually facilitate breeding of more disease resistant animals. The objective of this research was to profile the expression of ovine hepatic genes in response to Escherichia coli LPS challenge (0, 200, 400 ng/kg) using a bovine cDNA microarray and quantitative real-time PCR (qRT-PCR).
  
  
  RESULTS
  Twelve yearling ewes were challenged iv with E. coli LPS (0, 200, 400 ng/kg) and liver biopsies were collected 4-5 hours post-challenge to assess hepatic gene expression profiles by bovine cDNA microarray and qRT-PCR analyses. The expression of CD14, C3, IL12R, NRAMP1, SOD and IGFBP3 genes was down regulated, whereas the expression of ACTHR, IFNalphaR, CD1, MCP-1 and GH was increased during LPS challenge. With the exception of C3, qRT-PCR analysis of 7 of these genes confirmed the microarray results and demonstrated that GAPDH is not a suitable housekeeping gene in LPS challenged sheep.
  
  
  CONCLUSIONS
  We have identified several potentially important genes by bovine cDNA microarray and qRT-PCR analyses that are differentially expressed during the ovine hepatic response to systemic LPS challenge. Their potential role in regulating the inflammatory response to LPS warrants further investigation.
authors.affiliation: Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, N1G 2W1, Canada. hcao@uoguelph.ca <hcao@uoguelph.ca>
authors.forename: Honghe
authors.initials: H
authors.lastname: Cao
authors.forename: Leah C
authors.initials: LC
authors.lastname: Kabaroff
authors.forename: Qiumei
authors.initials: Q
authors.lastname: You
authors.forename: Alexander
authors.initials: A
authors.lastname: Rodriguez
authors.forename: Herman J
authors.initials: HJ
authors.lastname: Boermans
authors.forename: Niel A
authors.initials: NA
authors.lastname: Karrow
mesh_terms: D000818:Animals; D002417:Cattle / Q000235:genetics*; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli; D005260:Female; D020869:Gene Expression Profiling / Q000662:veterinary*; D005786:Gene Expression Regulation / Q000187:drug effects*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008099:Liver / Q000187:drug effects* / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis / Q000662:veterinary*; D016133:Polymerase Chain Reaction / Q000662:veterinary; D012756:Sheep / Q000235:genetics*
chemical_list: D008070:Lipopolysaccharides