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Hepatic thrombopoietin mRNA is increased in acute inflammation
E M Wolber1, J Fandrey, U Frackowski
1Institute of Physiology, Medical University of Luebeck, Germany. wolber@physio.mu-luebeck.de
Abstract:
The plasma concentration of thrombopoietin (TPO) in general is inversely related to the mass of platelets and megakaryocytes. However, reactive thrombocytosis of inflammatory disease is accompanied by elevated TPO levels. To investigate whether the rate of TPO mRNA expression is altered during acute inflammation, rats were injected with bacterial lipopolysaccharide (LPS). After 6 h, total RNA from liver and kidney was reverse transcribed and analyzed by competitive PCR for TPO and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). LPS-treated rats showed a significant increase in hepatic TPO mRNA concentration. The ratio of TPO to GAPDH mRNA was 3.5 +/- 0.6% in the livers of control rats and 8.3 +/- 2.0% in the livers of LPS-treated rats (mean +/- SD). Thus, reactive thrombocytosis of inflammatory disease might result from an increase in hepatic TPO production. Since platelets are involved in the immune reaction, reactive thrombocytosis may be a mechanism of host defense.
Insights
Acute inflammation increases thrombopoietin (TPO) production in the liver, potentially explaining reactive thrombocytosis. This suggests elevated platelet counts during inflammation may be a host defense mechanism.
Area of Science:
- Hematology
- Immunology
- Molecular Biology
Background:
- Plasma thrombopoietin (TPO) levels typically correlate inversely with platelet and megakaryocyte mass.
- Reactive thrombocytosis, observed in inflammatory conditions, is paradoxically associated with elevated TPO levels.
Purpose of the Study:
- To investigate alterations in TPO mRNA expression during acute inflammation.
- To determine if hepatic TPO production increases in response to inflammatory stimuli.
Main Methods:
- Rats were administered bacterial lipopolysaccharide (LPS) to induce acute inflammation.
- Liver and kidney RNA were analyzed using competitive PCR for TPO and GAPDH mRNA levels after 6 hours.
Main Results:
- LPS-treated rats exhibited a significant increase in hepatic TPO mRNA concentration.
- The ratio of TPO to GAPDH mRNA in the liver increased from 3.5% in controls to 8.3% in LPS-treated rats.
Conclusions:
- Increased hepatic TPO production may underlie reactive thrombocytosis in inflammatory diseases.
- Reactive thrombocytosis could serve as a host defense mechanism, given platelets' role in immune responses.