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Sublethal doses of exogenous hydrogen peroxide prime human neutrophils to formyl peptide
E A Puchnina-Artushenko1, A V Ledenev, E K Ruuge
1Institute of Experimental Cardiology, Moscow, Russia.
Abstract:
Hydrogen peroxide (H2O2) is an oxidative agent important in inflammation and ischemia. Neutrophils (PMNs) are a main source of H2O2 in the inflammatory focus. However, after recruitment into the inflammatory or ischemic zone of the heart, the PMN itself might serve as a target for exogenous H2O2. In the present work we found that PMNs are very resistant to the cytotoxic action of H2O2 (LD50 for PMNs is about 30-50 mM, whereas for endothelial cells it is about 200-300 microM). Unexpectedly, treatment of PMNs by H2O2 at a sublethal dose of 10 mM leads to a subsequent increase in the generation of superoxide anion in response to the chemoattractant peptide FMLP (twofold increase in O2- generation 30 min after treatment by H2O2 as compared with nontreated control cells). H2O2 itself does not induce O2- generation by PMNs. Therefore, any H2O2 that accumulated in the inflammatory or ischemic zone might alter the functional activity of PMNs and prime them to subsequent agonist activation.
Insights
Hydrogen peroxide (H2O2) is crucial in inflammation. Surprisingly, sublethal H2O2 exposure primes neutrophils (PMNs) to generate more superoxide anion when stimulated, altering their function in inflammatory sites.
Area of Science:
- Immunology
- Cellular Biology
- Oxidative Stress Research
Background:
- Hydrogen peroxide (H2O2) is a key oxidative agent in inflammation and ischemia.
- Neutrophils (PMNs) produce H2O2 at inflammatory sites but can also be targets of it.
- Endothelial cells are sensitive to H2O2, unlike PMNs.
Purpose of the Study:
- To investigate the effect of exogenous hydrogen peroxide on neutrophil function.
- To determine the cytotoxic threshold of H2O2 for neutrophils.
- To assess if H2O2 alters neutrophil responsiveness to agonists.
Main Methods:
- Exposure of neutrophils to varying concentrations of H2O2.
- Measurement of neutrophil cytotoxicity (LD50).
- Assessment of superoxide anion (O2-) generation in response to formyl-methionyl-leucyl-phenylalanine (FMLP) after H2O2 treatment.
Main Results:
- Neutrophils exhibit high resistance to H2O2's cytotoxic effects (LD50 ~30-50 mM).
- Sublethal H2O2 treatment (10 mM) significantly enhances subsequent superoxide anion generation by PMNs in response to FMLP.
- H2O2 alone does not induce superoxide anion generation in neutrophils.
Conclusions:
- Neutrophils are remarkably resistant to hydrogen peroxide-induced cytotoxicity.
- Accumulated H2O2 in inflammatory/ischemic areas can prime neutrophils, increasing their functional response to agonists.
- This priming effect suggests H2O2 plays a role in modulating neutrophil activity during inflammation and ischemia.