A high-grain diet causes massive disruption of ruminal epithelial tight junctions in goats

作者：Liu, Jun-hua; Xu, Ting-ting; Liu, Yu-jie; Zhu, Wei-yun; Mao, Sheng-yong^*

来源：American Journal of Physiology - Regulatory, Integrative and Comparative Physiology, 2013, 305(3): R232-R241.

DOI：10.1152/ajpregu.00068.2013

• rumen epithelium
• high-grain diet
• tight junction protein
• lipopolysaccharide
• inflammation

Alterations in rumen epithelial tight junctions (TJs) at the tissue and molecular levels during high-grain (HG) diet feeding are unknown. Here, 10 male goats were randomly assigned to either a hay diet (0% grain; n = 5) or HG diet group (65% grain; n = 5) to characterize the changes in ruminal epithelial structure and TJ protein expression and localization using scanning and transmission electron microscopy, quantitative real-time PCR, Western blot analysis, and immunofluorescence. After 7 wk of feeding, ruminal free LPS in HG group increased significantly (P < 0.001) compared with the hay group, and free LPS in the peripheral blood was detectable with concentrations of 0.8 +/- 0.20 EU/ml, while not detectable in the control, suggesting a leakage of LPS into the blood in the HG group. Correspondingly, the HG-fed goats showed profound alterations in ruminal epithelial structure and TJ proteins, depicted by marked epithelial cellular damage and intercellular junction erosion, down-regulation of TJ proteins claudin-4, occludin, and zonula occludens-1 mRNA and protein expression, as well as redistribution of claudin-1, claudin-4, and occludin. Furthermore, these changes in TJ proteins in the HG group were coupled with the upregulation of mRNA levels for the cytokines TNF-alpha and IFN-gamma in the ruminal epithelia. These results demonstrated for the first time that the HG diet feeding caused disruption of ruminal epithelial TJs that was associated with a local inflammatory response in the rumen epithelium. These findings may provide new insights into understanding the role of TJ proteins in the ruminal epithelial immune homeostasis of ruminants.

• 出版日期2013-8
• 单位南京农业大学