Research article

Characterization of ovine hepatic gene expression profiles in response to Escherichia coli lipopolysaccharide using a bovine cDNA microarray

Honghe Cao¹ , Leah C Kabaroff¹ , Qiumei You¹ , Alexander Rodriguez² , Herman J Boermans³ and Niel A Karrow¹

¹  Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, N1G 2W1, Canada

²  Department of Clinical Studies, University of Guelph, Guelph, Ontario, N1G 2W1, Canada

³  Department of Biomedical Science, University of Guelph, Guelph, Ontario, N1G 2W1, Canada

author email corresponding author email

BMC Veterinary Research 2006, 2:34doi:10.1186/1746-6148-2-34

Published:	29 November 2006

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, IFNαR, 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.

Conclusion

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.