title: Feeding a high-grain diet reduces the percentage of LPS clearance and enhances immune gene expression in goat liver.
abstract: BACKGROUND
  The effects of feeding a high-grain (HG) diet on lipopolysaccharide (LPS) clearance and innate immune defence responses in the liver remain unclear. Therefore, we conducted the present study in which twelve female goats were randomly assigned to either a treatment group fed a HG diet (60% grain, n = 6) or a control group fed a low grain diet (LG; 40% grain, n = 6) for 6 weeks. Catheters were installed in the mesenteric, portal and hepatic veins, as well as one femoral artery of the goats, for determining blood flow and net clearance rate of LPS in the liver. Plasma and tissue samples were collected in the week 6 for analyzing pro-inflammatory cytokines, acute phase protein and biochemical parameters, as well as expression of genes involved in immune response.
  
  
  RESULTS
  HG diet feeding increased blood flow and LPS concentration in the portal vein, hepatic vein and artery. Hepatic net LPS clearance showed that HG diet feeding elevated the rate of hepatic LPS clearance, but decreased the percentage of removed LPS accounting for the total entry of LPS into the liver. Our results demonstrated that the feeding of HG diet increased plasma concentrations of pro-inflammatory cytokines and acute phase proteins and triggered a systemic inflammatory response. In addition, peripheral blood plasma concentrations of alanine aminotransferase, alkaline phosphatase and total bilirubin were increased in the HG group compared to the LG group. This indicated that the impairment of hepatocytes occurred after 6 weeks of HG diet feeding. The expression of genes involved in immune response and Toll-like receptor (TLR)4 protein in the liver was up-regulated in the HG group compared to the LG group, indicating that increased entry of LPS enhanced hepatic immune defence responses and contributed to hepatic inflammatory responses.
  
  
  CONCLUSIONS
  These results provide insight into the capacity of the liver to clear LPS. The increased entry of LPS into liver enhanced hepatic immune defence responses, thereby elevated the rate of LPS clearance. However, the reduction of the percentage of hepatic LPS clearance could be due to the formation of hepatocyte lesion during HG diet feeding.
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, PR, China. 2011207036@njau.edu.cn.
authors.forename: Guangjun
authors.initials: G
authors.lastname: Chang
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, PR, China. zhangkai11895452@126.com.
authors.forename: Kai
authors.initials: K
authors.lastname: Zhang
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, PR, China. tl-xu@outlook.com.
authors.forename: Tianle
authors.initials: T
authors.lastname: Xu
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, PR, China. 2012107099@njau.edu.cn.
authors.forename: Di
authors.initials: D
authors.lastname: Jin
authors.affiliation: Leibniz Institute for Farm Animal Biology, Wilhelm-Stahl-Allee 2, 18196, Dummerstorf, Germany. seyfert@fbn-dummerstorf.de.
authors.forename: Hans-Martin
authors.initials: HM
authors.lastname: Seyfert
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, PR, China. xzshen@njau.edu.cn.
authors.forename: Xiangzhen
authors.initials: X
authors.lastname: Shen
authors.affiliation: College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, 210095, PR, China. zhuangsu@njau.edu.cn.
authors.forename: Su
authors.initials: S
authors.lastname: Zhuang
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D004032:Diet / Q000662:veterinary*; D002523:Edible Grain; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology*; D006041:Goats / Q000502:physiology*; D008070:Lipopolysaccharides / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*
chemical_list: D008070:Lipopolysaccharides