Immune Regulatory Functions of Liver in Ruminants
The liver is the biggest and complex digestive gland in ruminant. The liver participates in bodys digestion, absorption, excretion, detoxifcation, substance transportation and energy metabolism. The livers function is regulated by substrate supply and by endocrine hormones. The main methods for liver function research are multiple hepatic catheters technique, in vivo sampling and in vitro cell and tissue culture. With the development of immunology, studies shows that liver plays an important role in the regulation of bodys immune function. The main compositive cells of the liver have immune regulation function, which are Kupffers cells, essential cells and epithelial cells of hepatic sinus. The immune regulatory factors secreted by liver include TNF-α, IL-1, IL-6, NO and PGE2 etc. Endotoxin lipopolysaccharide (LPS) is a kind of macromolecule substance, and its the main component of ectoblast of Grams negative bacteria. LPS in ruminants body mainly is derived from rumen metabolism. When ruminant animals are fed high concentrate, lactic acid accumulated in the rumen leads to death of Grams negative bacteria and LPS is released. When LPS is absorbed by the body, it has an effect on bodys immune function. LPS has both harmful and advantageous effect on the body. The liver plays an important role in destroying and eliminating LPS. When liver is stimulated by LPS, it releases immune regulatory substance to regulate livers and whole bodys immune function. Surgical installation of multiple hepatic catheters in ruminant and infusion of LPS via portal vein can be as a model to study the effect of liver on body immune regulation. When LPS enters into liver, it combines with LBP and CD14 and activate monocyte-macrophage system to trigger production of cytokine. Toll-like receptor (TLR4) distributing in liver tissue can also recognize LPS and activate TLR4 signal pathway and promote cytokine release. LPS induces liver to produce bioactive cytokine to support immune response by providing nutrient substance expenditure. Ruminants re-partition their metabolic substrate supply in the face of immune stresses, and the available substrate supply diverted to processes vital for the animals own life, so the performance of ruminant animal is reduced.
Xiangzhen Shen Weimin Liu Jie Chen
Key Laboratory of Animal Physiology and Biochemistry, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, China
国际会议
奶牛营养与牛奶质量国际研讨会(ist International Symposium on Dairy Cow Nutrition and Milk Quality)
北京
英文
82-85
2009-05-04（万方平台首次上网日期，不代表论文的发表时间）