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Production of macrophage colony-stimulating factor by murine liver in vivo
1Department of Microbiology and Immunology, Nippon Medical School, Tokyo, Japan.
Abstract:
In previous reports, the authors demonstrated that M-CSF was produced by primary-cultured non-parenchymal (NPLC) and parenchymal (PLC) liver cells. In order to clarify the biological role of M-CSF produced by the liver, macrophage colony-stimulating factor (M-CSF)-producing cells in vivo were investigated using reverse transcriptase polymerase chain reaction (RT-PCR), dot blot analysis, in situ hybridization and immunohistochemistry. M-CSF mRNA was constantly identified by RT-PCR in the liver, NPLC and PLC, before and after partial hepatectomy. Dot blot analysis showed that fluctuations of M-CSF mRNA level after partial hepatectomy were not statistically significant. In situ hybridization revealed that M-CSF mRNA was expressed mainly in NPLC and vascular endothelial cells (VEC). In addition, a small number of PLC also expressed M-CSF mRNA. Neither the distribution nor the frequency of M-CSF mRNA positive cells in regenerative livers differed significantly from normal livers. M-CSF immunoreactivity was present in NPLC and VEC at all the times before and after partial hepatectomy, while PLC exhibited M-CSF immunostaining 0.5 days after partial hepatectomy. As normal liver expressed M-CSF mRNA to the same degree as regenerative liver, hepatic M-CSF mRNA production in vivo may be related to the physiological function of the liver. However, transient expression of M-CSF protein in PLC at an early stage after partial hepatectomy may be associated with liver regeneration.
Insights
Macrophage colony-stimulating factor (M-CSF) is produced by liver cells. While M-CSF mRNA is consistently found in normal and regenerating livers, M-CSF protein expression in parenchymal cells is transiently increased after partial hepatectomy, suggesting a role in liver regeneration.
Area of Science:
- Hepatology
- Immunology
- Cell Biology
Background:
- Previous studies identified macrophage colony-stimulating factor (M-CSF) production by cultured liver cells.
- The in vivo biological role of hepatic M-CSF remains to be fully elucidated.
Purpose of the Study:
- To investigate the in vivo expression and cellular localization of M-CSF mRNA and protein in the liver.
- To clarify the role of hepatic M-CSF during liver regeneration.
Main Methods:
- Reverse transcriptase polymerase chain reaction (RT-PCR) for M-CSF mRNA detection.
- Dot blot analysis to quantify M-CSF mRNA levels.
- In situ hybridization to determine M-CSF mRNA localization.
- Immunohistochemistry to assess M-CSF protein expression.
Main Results:
- M-CSF mRNA was constitutively expressed in normal and regenerating livers, with no significant changes after partial hepatectomy.
- M-CSF mRNA was primarily localized to non-parenchymal liver cells (NPLC) and vascular endothelial cells (VEC), with some expression in parenchymal cells (PLC).
- M-CSF protein was detected in NPLC and VEC throughout, but showed transient upregulation in PLC at 0.5 days post-hepatectomy.
Conclusions:
- Hepatic M-CSF mRNA production is likely related to normal liver physiology.
- Transient M-CSF protein expression in PLC following partial hepatectomy suggests a role in the early stages of liver regeneration.