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Acute-phase hepatocytes regulate liver sinusoidal cell mediator production
1Department of Surgery, University of Texas, Southwestern Medical Center, Dallas.
Archives of Surgery (Chicago, Ill. : 1960)
|November 1, 1994
Summary
Pre-stimulating liver cells with interleukin-6 (IL-6) limits the production of inflammatory mediators like tumor necrosis factor (TNF) and nitric oxide in response to lipopolysaccharide (LPS). This suggests a protective role for hepatocytes in limiting liver injury during infection.
Area of Science:
- Hepatology
- Immunology
- Cell Biology
Background:
- Overproduction of liver sinusoidal cell (LSC) mediators can cause hepatic dysfunction during endotoxemia or gram-negative infections.
- Hepatocyte-derived acute-phase reactants may play a role in regulating these mediator productions.
Purpose of the Study:
- To investigate how interleukin-6 (IL-6) prestimulation affects hepatocyte regulation of lipopolysaccharide (LPS)-induced mediator production by LSCs.
- To define the role of acute-phase reactants in response to sequential inflammatory insults.
Main Methods:
- Isolated rat hepatocytes and LSCs, comparing responses in LSCs alone versus hepatocyte-LSC cocultures.
- Sequential stimulation with IL-6 then LPS, analyzing TNF, IL-6, and nitric oxide production.
- Assessed acute-phase protein synthesis and quantified cytokine mRNA levels via RT-PCR.
Main Results:
- IL-6 and dexamethasone induce hepatocyte acute-phase protein synthesis.
- IL-6 prestimulation of cocultures significantly inhibited LPS-induced IL-6 and nitric oxide production, with reduced TNF bioactivity.
- Messenger RNA levels for TNF and IL-6 remained similar despite functional inhibition.
Conclusions:
- Hepatocytes stimulated with IL-6 can limit the bioactivity of cytokines and nitric oxide produced by LSCs in response to LPS.
- This hepatocyte-mediated regulation may serve as a local counterregulatory mechanism to mitigate LSC-induced liver injury.