Anti-Inflammatory Activity of Dehydroandrographolide by TLR4/NF-κB Signaling Pathway Inhibition in Bile Duct-Ligated Mice

Abstract

Background/Aims: Clinically, biliary obstruction is often accompanied by progressive inflammation. Dehydroandrographolide (DA) possesses anti-inflammatory properties. However, the anti-inflammatory activities of DA in cholestatic liver injury remain unclear. Methods: Mice were administered with DA by intraperitoneal injection after bile duct ligation (BDL) on day 1. Then mice were subjected to an ileocecal vein injection of lipopolysaccharide (LPS). Liver function markers, histology, pro-inflammatory cytokine levels, NF-κB activation and fibrosis formation were evaluated in BDL mice with LPS. LPS binding to primary Kupffer cells was examined by high-content cytometers. Results: DA was shown to greatly lower initially higher than normal levels of alanine aminotransferase (ALT) and total bilirubin (TBIL) in the serum and liver of BDL mice with LPS. DA exerted hepatic protective effects that were also confirmed by prolonged survival of BDL mice with LPS. Liver histopathology showed reduced inflammatory cellular infiltration, bile duct proliferation, and biliary necrosis with DA treatment. Furthermore, DA reduced the expression levels of tumor necrosis factor (TNF)-α and interleukin (IL)-6 in liver tissue and plasma and showed decreased NF-κB activation in BDL mice with LPS. DA could prevent LPS binding to primary Kupffer cells in the normal liver and BDL mice liver. DA also suppressed LPS-stimulated inflammatory responses by blocking the interaction between LPS and TLR4 in primary Kupffer cells and human LX-2 cells, thereby inhibiting NF-κB activation. Conclusion: DA inhibition of inflammation against liver damage following BDL with LPS may be a promising agent for the treatment of cholestatic liver injury.

Keywords

• Dehydroandrographolide
• Cholestatic liver injury
• Inflammation
• TLR4
• NF-κB activation