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Kupffer cell factor mediated depression of hepatic parenchymal cell cytochrome P-450
Abstract:
Following the administration of latex particles (0.46 micron), cytochrome P-450 dependent monooxygenase system was depressed in the livers of mice. These particles were taken up exclusively by Kupffer cells in the liver, and no particles were found in the hepatocytes which contain most of the monooxygenase capacity in that organ. Cytochrome P-450 was also depressed in isolated hepatocytes incubated with phagocytosing Kupffer cells or the cell free filtrate from an incubation mixture of Kupffer cells and latex particles. Kupffer cells and hepatocytes were then incubated in a double-chambered vessel in which the two cell types were separated by a semi-permeable membrane. When latex particles were added to the chamber containing Kupffer cells, a factor was released which crossed the semi-permeable membrane and depressed cytochrome P-450 and benzo[a]pyrene hydroxylase in hepatocytes contained in the other chamber. It is concluded that, during the process of phagocytosis (in vivo or in vitro) by Kupffer cells in the liver, the levels of cytochrome P-450 and related drug biotransformation were depressed in the adjacent parenchymal cells.
Insights
Phagocytosis by Kupffer cells in mouse liver releases a factor that depresses cytochrome P-450 and drug metabolism in nearby hepatocytes. This finding impacts understanding of liver drug biotransformation.
Area of Science:
- Hepatology
- Immunology
- Pharmacology
Background:
- Cytochrome P-450 enzymes are crucial for drug metabolism in liver hepatocytes.
- Kupffer cells are the resident macrophages of the liver, involved in phagocytosis.
- The interaction between Kupffer cells and hepatocytes can influence liver function.
Purpose of the Study:
- To investigate the effect of Kupffer cell phagocytosis on cytochrome P-450 dependent monooxygenase system in mouse liver.
- To identify the mechanism by which Kupffer cell activity impacts hepatocyte drug metabolism.
Main Methods:
- Administration of latex particles to mice and observation of liver enzyme activity.
- In vitro incubation of isolated Kupffer cells and hepatocytes.
- Use of a double-chambered vessel with a semi-permeable membrane to separate cell types.
Main Results:
- Latex particle uptake by Kupffer cells led to depression of cytochrome P-450 in the liver.
- Isolated hepatocytes showed depressed cytochrome P-450 when incubated with phagocytosing Kupffer cells or their filtrate.
- A soluble factor released from phagocytosing Kupffer cells suppressed cytochrome P-450 and benzo[a]pyrene hydroxylase in adjacent hepatocytes.
Conclusions:
- Kupffer cell phagocytosis releases a factor that negatively impacts cytochrome P-450 levels and drug biotransformation in adjacent hepatocytes.
- This interaction suggests a paracrine signaling mechanism between Kupffer cells and hepatocytes affecting drug metabolism.
- The findings highlight the role of Kupffer cells in modulating liver drug metabolism, particularly during inflammatory or phagocytic events.