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The interval between a septic stimulus and hypoxia/reoxygenation affects cytokine elaboration by murine peritoneal
1Division of Pediatric Surgery, Children's Hospital Medical Center, Cincinnati, OH 45229-3039, USA.
Abstract:
The critically ill patient is commonly exposed to various physiological insults. The authors have previously shown that in vivo hypoxia/reoxygenation (H/R) alters the pattern of cytokines elaborated by murine peritoneal macrophages given a septic stimulus. In this study they sought to determine whether the interval between a septic stimulus and H/R affected the release of inflammatory mediators by macrophages. Adult CBA-strain mice were injected intraperitoneally with 10 micrograms of lipopolysaccharide (LPS). On day 0, 1, 2, 3, 4, or 5 after LPS injection, animals were exposed to 16 hours of hypoxia followed by 2 hours of reoxygenation. Harvested peritoneal macrophages were restimulated in vitro with 2.5 micrograms/mL LPS or left unstimulated. Culture supernatants collected at 2, 4, 6, 8, 10, and 12 hours after LPS injection were assayed for tumor necrosis factor (TNF), prostaglandin E2 (PGE2), and nitric oxide (NO) production. Macrophage-derived mediator production peaked when H/R occurred 3 days following LPS injection (P < .05). These data suggest that the interval between sepsis and subsequent H/R influences the pattern of cytokines elaborated by peritoneal macrophages given a septic stimulus.
Insights
The timing of hypoxia/reoxygenation (H/R) after a sepsis stimulus significantly impacts inflammatory mediator release from macrophages. Maximum mediator production occurred when H/R was administered 3 days post-sepsis.
Area of Science:
- Immunology
- Critical Care Medicine
Background:
- Critically ill patients often experience physiological insults like hypoxia/reoxygenation (H/R).
- Previous research indicated H/R alters cytokine patterns in macrophages stimulated by sepsis.
Purpose of the Study:
- To investigate how the time interval between a sepsis stimulus and H/R affects inflammatory mediator release from macrophages.
- To determine the optimal timing for H/R to influence macrophage-derived inflammatory mediators.
Main Methods:
- Mice received lipopolysaccharide (LPS) to induce sepsis.
- Animals underwent H/R at various time points (0-5 days) post-LPS.
- Peritoneal macrophages were isolated, restimulated with LPS in vitro, and supernatants were analyzed for TNF, PGE2, and NO production.
Main Results:
- Macrophage mediator production peaked when H/R was performed 3 days after LPS injection.
- A statistically significant difference (P < .05) was observed in mediator production based on the H/R timing.
- The interval between sepsis and H/R modulated the release of inflammatory mediators.
Conclusions:
- The temporal relationship between sepsis and subsequent H/R is a critical factor influencing macrophage inflammatory responses.
- Understanding this interval can inform therapeutic strategies for critically ill patients.
- Macrophage activation patterns are dynamic and sensitive to the timing of secondary insults.