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Oncostatin M production and regulation by human polymorphonuclear neutrophils
A Grenier1, M Dehoux, A Boutten
1Laboratoire de Biochimie, Hôpital de Montfermeil, Montfermeil, France.
Abstract:
Oncostatin M (OSM) is an interleukin-6 (IL-6) family cytokine known in particular to induce the synthesis of acute-phase proteins by hepatocytes. Because human polymorphonuclear neutrophils (PMN) can secrete numerous cytokines, the potential production of OSM by PMN was investigated. Highly purified PMN were found to contain an intracellular stock of preformed OSM that was rapidly mobilized by degranulating agents such as phorbol myristate acetate and granulocyte-macrophage colony-stimulating factor (GM-CSF). Moreover, PMN produced OSM after a few hours of stimulation by various agonists. The most potent effect was observed with the combination of lipopolysaccharide and GM-CSF, which had a concentration- and time-dependent effect at both the protein and mRNA levels. Actinomycin D strongly reduced OSM mRNA induction, suggesting the involvement of gene transcription. Cycloheximide inhibited OSM protein synthesis but did not affect the release of preformed stores. In addition, OSM production was downregulated by dexamethasone, whereas IL-10 had no effect. The OSM produced by PMN was biologically active, as demonstrated by its ability to induce alpha1-acid glycoprotein synthesis by HepG2 cells. OSM secretion thus occurs through a two-step mechanism in PMN, consisting of early release of a preformed stock, followed by de novo protein synthesis. This would allow rapid and sustained OSM release to occur at inflammatory sites, and may contribute to the modulation of local inflammation.
Insights
Human neutrophils (PMN) release pre-formed Oncostatin M (OSM) and synthesize more upon stimulation, contributing to inflammation. This cytokine is biologically active, influencing acute-phase protein synthesis.
Area of Science:
- Immunology
- Cell Biology
- Cytokine Research
Background:
- Oncostatin M (OSM), an IL-6 family cytokine, is known to induce acute-phase protein synthesis in hepatocytes.
- Human polymorphonuclear neutrophils (PMN) are capable of secreting various cytokines.
- The potential for OSM production by PMN has not been fully elucidated.
Purpose of the Study:
- To investigate the production and secretion of Oncostatin M (OSM) by human polymorphonuclear neutrophils (PMN).
- To characterize the mechanisms regulating OSM release and synthesis in PMN.
- To assess the biological activity of PMN-derived OSM.
Main Methods:
- Purification of human PMN.
- Stimulation of PMN with various agents (e.g., PMA, GM-CSF, LPS, Dexamethasone, IL-10).
- Measurement of OSM protein and mRNA levels.
- Assessment of OSM biological activity using HepG2 cells.
Main Results:
- PMN contain and rapidly release pre-formed intracellular OSM upon stimulation with degranulating agents.
- PMN synthesize and release new OSM protein and mRNA following stimulation, particularly with LPS and GM-CSF.
- OSM production is regulated by gene transcription and protein synthesis, inhibited by Actinomycin D and Cycloheximide, respectively.
- Dexamethasone downregulates OSM production, while IL-10 has no significant effect.
- PMN-derived OSM is biologically active, inducing alpha1-acid glycoprotein synthesis.
Conclusions:
- PMN secrete OSM via a two-step mechanism: early release of pre-formed stores followed by de novo synthesis.
- This dual mechanism allows for rapid and sustained OSM release at inflammatory sites.
- PMN-derived OSM may play a significant role in modulating local inflammatory responses.