Related Experiment Videos
Regulation of interleukin-6 receptor expression in human monocytes and hepatocytes
Abstract:
Human blood monocytes normally express the interleukin-6 receptor. Treatment of cultured monocytes with endotoxin, interleukin-1 beta, or interleukin-6 results in a decrease in interleukin-6 receptor mRNA levels. Glucocorticoids aso cause a drop in monocytic interleukin-6 receptor mRNA levels. We also found interleukin-6 receptor expression in cultured human hepatocytes, but in contrast to monocytes, where interleukin-6 receptor mRNA is presented by the ligand and by interleukin-1, treatment of hepatocytes with interleukin-6 or interleukin-1 resulted in increased interleukin-6 receptor mRNA levels. Induction of interleukin-6 receptor mRNA in hepatocytes was less pronounced when glucocorticoids were omitted from the culture medium. We conclude that during noninflammatory homeostasis, blood monocytes are involved in binding of trace amounts of circulating interleukin-6. During inflammatory events, the main target of interleukin-6 may be changed from the monocytic population not only to activated B-cells, but also to the hepatocytes.
Insights
Human monocytes and hepatocytes express the interleukin-6 receptor. Inflammatory signals decrease this receptor on monocytes but increase it on hepatocytes, suggesting a shift in interleukin-6 targeting during inflammation.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- Interleukin-6 (IL-6) is a key cytokine involved in immune responses and inflammation.
- The interleukin-6 receptor (IL-6R) mediates the biological effects of IL-6.
- Understanding IL-6R expression dynamics in different cell types is crucial for comprehending inflammatory processes.
Purpose of the Study:
- To investigate the regulation of interleukin-6 receptor (IL-6R) expression in human monocytes and hepatocytes.
- To determine how inflammatory stimuli and glucocorticoids affect IL-6R mRNA levels in these cells.
Main Methods:
- Primary human monocytes and hepatocytes were cultured in vitro.
- Cells were treated with endotoxin, interleukin-1 beta (IL-1β), interleukin-6 (IL-6), and glucocorticoids.
- Interleukin-6 receptor mRNA levels were quantified using quantitative reverse transcription PCR.
Main Results:
- Monocytes normally express IL-6R; endotoxin, IL-1β, IL-6, and glucocorticoids decreased monocytic IL-6R mRNA levels.
- Hepatocytes also express IL-6R; IL-6 and IL-1β increased hepatocyte IL-6R mRNA levels.
- Glucocorticoids enhanced the induction of IL-6R mRNA in hepatocytes, but their omission reduced this effect.
Conclusions:
- During homeostasis, monocytes bind circulating IL-6.
- During inflammation, IL-6 targets shift from monocytes to activated B-cells and hepatocytes.
- Hepatocytes play a significant role in IL-6 signaling during inflammatory conditions, with expression modulated by glucocorticoids.