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Neutrophils augment the release of TNFalpha from LPS-stimulated macrophages via hydrogen peroxide
D Sredni-Kenigsbuch1, T Kambayashi, G Strassmann
1Interdisciplinary Department, Bar-Ilan University, Ramat Gan, Israel. srednid@mail.biu.ac.il
Abstract:
We examined the effect of polymorphonuclear cells on the release of tumor necrosis factor (TNFalpha) in endotoxin-treated macrophages. Human peripheral blood neutrophils were co-cultured with mouse peritoneal macrophages stimulated with lipopolysaccharide (LPS). In a dose-dependent manner, FMLP (n-formyl-methionyl-leucyl-phenylalanine) augmented the release of TNFalpha by LPS-stimulated macrophages in the presence, but not in the absence, of neutrophils. The stimulating effect of neutrophils on macrophages was reversed by catalase, suggesting that the release of hydrogen peroxide from neutrophils was responsible for augmenting macrophage TNFalpha. Moreover, the direct addition of hydrogen peroxide to macrophages resulted in an increased secretion of TNFalpha. In addition, insertion of a porous membrane between the neutrophils and macrophages cancelled the effect, indicating that adherence of neutrophils may be necessary for augmentation of TNFalpha release. In summary, the data suggest that hydrogen peroxide released from stimulated neutrophils may act as an activator of macrophage function by increasing their release of TNFalpha.
Insights
Neutrophils enhance tumor necrosis factor (TNFalpha) release from macrophages stimulated by lipopolysaccharide (LPS). This effect is mediated by hydrogen peroxide and requires neutrophil adherence, suggesting a novel inflammatory pathway.
Area of Science:
- Immunology
- Cell Biology
Background:
- Macrophages play a critical role in immune responses, including the production of pro-inflammatory cytokines like TNFalpha.
- Neutrophils are key players in acute inflammation and can interact with macrophages.
Purpose of the Study:
- To investigate the effect of polymorphonuclear cells (neutrophils) on TNFalpha release from macrophages stimulated with LPS.
- To elucidate the mechanism by which neutrophils influence macrophage TNFalpha production.
Main Methods:
- Co-culture of human peripheral blood neutrophils with mouse peritoneal macrophages stimulated by LPS.
- Stimulation of neutrophils with FMLP to assess their effect on TNFalpha release.
- Use of catalase to investigate the role of hydrogen peroxide.
- Separation of cells using a porous membrane to assess the necessity of adherence.
Main Results:
- Neutrophils augmented LPS-induced TNFalpha release from macrophages in a dose-dependent manner.
- This augmentation was dependent on the presence of neutrophils and was reversed by catalase, indicating the involvement of hydrogen peroxide.
- Direct addition of hydrogen peroxide to macrophages increased TNFalpha secretion.
- The effect was abolished when neutrophils and macrophages were separated by a porous membrane, suggesting adherence is necessary.
Conclusions:
- Hydrogen peroxide released from stimulated neutrophils acts as a mediator to augment TNFalpha release from macrophages.
- Neutrophil-macrophage interaction, potentially involving adherence and hydrogen peroxide signaling, plays a significant role in modulating inflammatory responses.