title: High-concentrate feeding upregulates the expression of inflammation-related genes in the ruminal epithelium of dairy cattle.
abstract: BACKGROUND
  The objective of this study was to characterize the mRNA expression profile related to rumen epithelial inflammation through the in vivo and in vitro experiments. In the in vivo experiment, rumen papillae were collected from four dairy cows adapted to either a 40 % (LC) or 70 % (HC) concentrate feeds for microarray analysis.
  
  
  RESULTS
  Results showed that 245 differentially expressed genes (DEGs) were detected in the cows fed the HC relative to the LC diet. The DEGs were first annotated, and results revealed that the expression of inflammation-related genes, including IL-1β, IL-2, IL-22, CCL19, CCL8, CX3CR1, CXCL6, INHBE, LEPR, PRL, and TNFRSF9 found in the cytokine-cytokine receptor pathway were up-regulated in the HC-fed cows, indicating local inflammation in the rumen epithelium was triggered. The expression of IL-1β, IL-2, and IL-6 was further validated by qRT-PCR. To demonstrate whether there were relationships between cytokine mRNA expression and ruminal factors (pH and LPS), the isolated ruminal epithelial cells were cultured in vitro. Results showed that the mRNA expression of IL-1β, IL-2, IL-6, and IL-8 increased after the LPS treatment, while low-pH treatment elevated the mRNA expression of TNF-α, suggesting that low-pH coupled with higher levels of LPS in rumen of cows fed the HC may be mainly responsible for the triggered local ruminal inflammation.
  
  
  CONCLUSIONS
  Our results indicate that ruminal local inflammation response might be triggered during HC feeding, and these findings also enhance the knowledge of rumen epithelial adaptation to HC at the molecular level.
authors.affiliation: Laboratory of Gastrointestinal Microbiology, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, 210095 Peoples Republic of China.
authors.forename: Ruiyang
authors.initials: R
authors.lastname: Zhang
authors.affiliation: Laboratory of Gastrointestinal Microbiology, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, 210095 Peoples Republic of China.
authors.forename: Weiyun
authors.initials: W
authors.lastname: Zhu
authors.affiliation: Laboratory of Gastrointestinal Microbiology, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, 210095 Peoples Republic of China.
authors.forename: Shengyong
authors.initials: S
authors.lastname: Mao
keywords: Dairy cows; Gene expression; Microarray; Subacute ruminal acidosis