A high-grain diet causes massive disruption of ruminal epithelial tight junctions in goats
A high-grain diet causes massive disruption of ruminal epithelial tight junctions in goats
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高谷物饮食会导致山羊瘤胃上皮紧密连接的大量破坏。
DOI：
10.1152/ajpregu.00068.2013
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发表时间：
2013-08-01
影响因子：
2.8
通讯作者：
Mao, Sheng-yong
中科院分区：
文献类型：
--
作者：
Liu, Jun-hua;Xu, Ting-ting;Mao, Sheng-yong
在高谷物(HG)日粮饲养期间，瘤胃上皮紧密连接(TJ)在组织和分子水平上的变化尚不清楚。将10只雄性山羊随机分为干草日粮组(0%谷物，n=5)和HG组(65%谷物，n=5)，利用扫描和透射电子显微镜、实时定量聚合酶链式反应、Western印迹分析和免疫荧光技术研究瘤胃上皮结构的变化和TJ蛋白的表达和定位。饲喂7wk后，HG组瘤胃内游离内毒素显著高于干草组(P<0.001)，外周血中可检测到游离内毒素，浓度为0.80±0.20EU/ml，而对照组未检测到，提示HG组有内毒素渗入血液。相应地，饲喂HG的山羊瘤胃上皮结构和TJ蛋白发生了深刻的变化，表现为显著的上皮细胞损伤和细胞间连接侵蚀，TJ蛋白claudin-4、occludin和zonula occludens-1的mRNA和蛋白表达下调，以及claudin-1、claudin-4和occludin的重新分布。此外，HG组TJ蛋白的这些变化与瘤胃上皮细胞因子肿瘤坏死因子-α和干扰素-γ的表达上调有关。这些结果首次证明了HG饲料引起瘤胃上皮细胞的破坏，这与瘤胃上皮的局部炎症反应有关。这些发现可能为理解TJ蛋白在反刍动物瘤胃上皮免疫动态平衡中的作用提供新的见解。
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.