Toll-like receptor 4 mediates inflammatory signaling by bacterial lipopolysaccharide in human hepatic stellate cells

Hepatology. 2003 May;37(5):1043-55. doi: 10.1053/jhep.2003.50182.


Bacterial lipopolysaccharide (LPS) stimulates Kupffer cells and participates in the pathogenesis of alcohol-induced liver injury. However, it is unknown whether LPS directly affects hepatic stellate cells (HSCs), the main fibrogenic cell type in the injured liver. This study characterizes LPS-induced signal transduction and proinflammatory gene expression in activated human HSCs. Culture-activated HSCs and HSCs isolated from patients with hepatitis C virus-induced cirrhosis express LPS-associated signaling molecules, including CD14, toll-like receptor (TLR) 4, and MD2. Stimulation of culture-activated HSCs with LPS results in a rapid and marked activation of NF-kappaB, as assessed by in vitro kinase assays for IkappaB kinase (IKK), IkappaBalpha steady-state levels, p65 nuclear translocation, NF-kappaB-dependent luciferase reporter gene assays, and electrophoretic mobility shift assays. Lipid A induces NF-kappaB activation in a similar manner. Both LPS- and lipid A-induced NF-kappaB activation is blocked by preincubation with either anti-TLR4 blocking antibody (HTA125) or Polymyxin B. Lipid A induces NF-kappaB activation in HSCs from TLR4-sufficient (C3H/OuJ) mice but not from TLR4-deficient (C3H/HeJ) mice. LPS also activates c-Jun N-terminal kinase (JNK), as assessed by in vitro kinase assays. LPS up-regulates IL-8 and MCP-1 gene expression and secretion. LPS-induced IL-8 secretion is completely inhibited by the IkappaB super repressor (Ad5IkappaB) and partially inhibited by a specific JNK inhibitor, SP600125. LPS also up-regulates cell surface expression of ICAM-1 and VCAM-1. In conclusion, human activated HSCs utilize components of TLR4 signal transduction cascade to stimulate NF-kappaB and JNK and up-regulate chemokines and adhesion molecules. Thus, HSCs are a potential mediator of LPS-induced liver injury.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Blood Proteins / pharmacology
  • Cells, Cultured
  • Chemokine CCL2 / metabolism
  • Drosophila Proteins*
  • Hepatocytes / cytology
  • Hepatocytes / physiology*
  • Humans
  • Intercellular Adhesion Molecule-1 / metabolism
  • Interleukin-8 / metabolism
  • JNK Mitogen-Activated Protein Kinases
  • Lipopolysaccharide Receptors / genetics
  • Lipopolysaccharide Receptors / metabolism
  • Lipopolysaccharides / pharmacology*
  • Liver Cirrhosis / immunology
  • Liver Cirrhosis / metabolism*
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / metabolism*
  • Mice
  • Mice, Inbred C3H
  • Mitogen-Activated Protein Kinases / metabolism
  • NF-kappa B / metabolism
  • Receptors, Cell Surface / genetics
  • Receptors, Cell Surface / metabolism*
  • Signal Transduction / drug effects
  • Signal Transduction / immunology*
  • Toll-Like Receptor 4
  • Toll-Like Receptors
  • Transcription Factor AP-1 / metabolism
  • Up-Regulation / drug effects
  • Up-Regulation / immunology
  • Vascular Cell Adhesion Molecule-1 / metabolism


  • Blood Proteins
  • Chemokine CCL2
  • Drosophila Proteins
  • Interleukin-8
  • Lipopolysaccharide Receptors
  • Lipopolysaccharides
  • Membrane Glycoproteins
  • NF-kappa B
  • Receptors, Cell Surface
  • TLR4 protein, human
  • Toll-Like Receptor 4
  • Toll-Like Receptors
  • Transcription Factor AP-1
  • Vascular Cell Adhesion Molecule-1
  • Intercellular Adhesion Molecule-1
  • JNK Mitogen-Activated Protein Kinases
  • Mitogen-Activated Protein Kinases