Delta-Like Ligand 4 Modulates Liver Damage by Down-Regulating Chemokine Expression

Area of Science:

• Hepatology and immunology research.
• Molecular mechanisms of liver injury and repair.

Background:

• Notch signaling disruption can improve liver fibrosis, but individual ligand roles remain unclear.
• Delta-like ligand 4 (Dll4) is a Notch ligand with an unknown function in liver disease.

Purpose of the Study:

• To investigate the role of Delta-like ligand 4 (Dll4) in liver disease.
• To determine the effects of Dll4 on liver injury, inflammation, and fibrosis in various models.

Main Methods:

• Immunohistochemistry to measure DLL4 expression in human liver tissues.
• In vivo studies using carbon tetrachloride and bile duct ligation mouse models.
• In vitro studies with hepatic stellate cells, hepatocytes, and Kupffer cells.
• Administration of recombinant Dll4 protein (rDll4) and recombinant Ccl2.

Main Results:

• DLL4 is expressed in Kupffer and liver sinusoidal endothelial cells in humans.
• rDll4 ameliorated hepatocyte apoptosis, inflammation, and fibrosis in carbon tetrachloride-induced liver injury.
• rDll4 exacerbated liver injury and caused mortality in bile duct ligation models, an effect rescued by Ccl2.
• Dll4 down-regulates chemokine expression via NF-κB, with inverse association between DLL4 and CCL2 in acute-on-chronic liver failure patients.

Conclusions:

• Dll4 plays a dual role in liver disease, ameliorating certain injuries while worsening others.
• Dll4 modulates the liver inflammatory response by down-regulating chemokine expression.
• Dysregulation of Dll4 and CCL2 may contribute to cytokine storms in liver failure.