Abstract
BackgroundThe 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.ResultsResults 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.ConclusionsOur 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.Electronic supplementary materialThe online version of this article (doi:10.1186/s40104-016-0100-1) contains supplementary material, which is available to authorized users.
Highlights
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
Ruminal pH, SCFA and LPS The results presented here must be interpreted in light of the overall effects of high-concentrate diet (HC) feeding on rumen fermentation in the experimental cattle reported in Mao’s prior study [15]
Blood chemistry and hematology parameters Compared with low-concentrate diet (LC) group, HC feeding led to an increase (P < 0.05) in white blood cells (WBC) and lymphocytes (Table 2), whereas HC treatments had no significant effects (P > 0.05) on the number of neutrophils and monocytes in blood
Summary
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. Many previous reports revealed that grain-induced SARA increased the levels of acute phase proteins such as haptoglobin (Hp) and serum amyloid A (SAA), which indicate a systemic inflammatory response in peripheral blood [6, 7]. This systemic inflammation is considered to be related with the diet-induced massive disruption of rumen epithelial barrier function [8] and increased permeability of the rumen epithelium [9], which aids microbes and immunogenic compounds to transmigrate into portal circulation [7], and further induces systemic inflammation. A study that used isolated rumen and colon tissue from steers demonstrated that LPS and decreased pH may act
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