Rumen-derived lipopolysaccharide provoked inflammatory injury in the liver of dairy cows fed a high-concentrate diet

Abstract

// Junfei Guo 1 , Guangjun Chang 1 , Kai Zhang 1 , Lei Xu 1 , Di Jin 1 , Muhammad Shahid Bilal 1 and Xiangzhen Shen 1 1 College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, P.R. China Correspondence to: Xiangzhen Shen, email: // Keywords : subacute ruminal acidosis, lipopolysaccharide, inflammatory injury, liver, dairy cows,  Immunology and Microbiology Section, Immune response, Immunity Received : January 09, 2017 Accepted : May 11, 2017 Published : May 24, 2017 Abstract Rumen-derived lipopolysaccharide (LPS) is translocated from the rumen into the bloodstream when subacute ruminal acidosis (SARA) occurs following long-term feeding with a high-concentrate (HC) diet in dairy cows. The objective of this study was to investigate the mechanism of inflammatory responses in the liver caused by HC diet feeding. We found that SARA was induced in dairy cows when rumen pH below 5.6 lasted for at least 3 h/d with HC diet feeding. Also, the LPS levels in the portal and hepatic veins were increased significantly and hepatocytes were impaired as well as the liver function was inhibited during SARA condition. Meanwhile, the mRNA expression of immune genes including TNF receptor associated factor 6 (TRAF6), nuclear factor-kappa B (NF-κB), p38 mitogen-activated protein kinase (MAPK), extracellular regulated protein kinases (ERK) MAPK, Interleukin-1 (IL-1) and serum amyloid A (SAA) in the liver were significantly increased in SARA cows. Moreover, the phosphorylation level of NF-κB p65 and p38 MAPK proteins in the liver and the concentration of Tumor Necrosis Factor (TNF-α), Interleukin-1β (IL-1β) and Interleukin-6 (IL-6) in peripheral blood were obviously increased under SARA condition. In conclusion, the inflammatory injury in the liver caused by LPS that traveled from the digestive tract to the liver through the portal vein after feeding with a HC diet.