title: A high-grain diet causes massive disruption of ruminal epithelial tight junctions in goats.
abstract: 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-α and IFN-γ 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.
authors.affiliation: Laboratory of Gastrointestinal Microbiology, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu Province, China.
authors.forename: Jun-hua
authors.initials: JH
authors.lastname: Liu
authors.forename: Ting-ting
authors.initials: TT
authors.lastname: Xu
authors.forename: Yu-jie
authors.initials: YJ
authors.lastname: Liu
authors.forename: Wei-yun
authors.initials: WY
authors.lastname: Zhu
authors.forename: Sheng-yong
authors.initials: SY
authors.lastname: Mao
mesh_terms: D000818:Animals; D015153:Blotting, Western; D001826:Body Fluids / Q000737:chemistry / Q000502:physiology; D057167:Claudins / Q000378:metabolism; D016207:Cytokines / Q000096:biosynthesis; D017931:DNA Primers; D018076:DNA, Complementary / Q000096:biosynthesis / Q000235:genetics; D004032:Diet / Q000009:adverse effects*; D002523:Edible Grain; D004848:Epithelium / Q000502:physiology; D005455:Fluorescent Antibody Technique; D006041:Goats; D006706:Homeostasis; D006863:Hydrogen-Ion Concentration; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D062793:Occludin / Q000378:metabolism; D012313:RNA / Q000096:biosynthesis / Q000302:isolation & purification; D060888:Real-Time Polymerase Chain Reaction; D012417:Rumen / Q000276:immunology / Q000473:pathology*; D019108:Tight Junctions / Q000276:immunology / Q000502:physiology*; D062826:Zonula Occludens-1 Protein / Q000378:metabolism
chemical_list: D057167:Claudins; D016207:Cytokines; D017931:DNA Primers; D018076:DNA, Complementary; D008070:Lipopolysaccharides; D062793:Occludin; D062826:Zonula Occludens-1 Protein; D012313:RNA
keywords: high-grain diet; inflammation; lipopolysaccharide; rumen epithelium; tight junction protein