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MAP kinases differentially regulate the expression of macrophage hyperactivity after thermal injury
Michelle Alexander1, Tanjanika Daniel, Irshad H Chaudry
1Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama, USA.
Abstract:
Thermal injury increases the capacity of macrophages (Mphi) to produce various inflammatory mediators, (i.e., Mphi hyperactivity), which is believed to be involved in the development of subsequent immunosuppression, sepsis, and multiple organ failure. The signal transduction pathways involved in the expression of Mphi hyperactivity post-burn, however, remain to be clearly elucidated. To study this C57BL/6 female mice were subjected to a 25% TBSA burn and splenic Mphis were isolated 7 days later. LPS-stimulated inflammatory mediator production and MAPK expression (P38 ERK 1/2 and JNK) were determined. Burn injury increased LPS-induced P38 MAPK, suppressed JNK activation and ERK 1/2 activation was unaltered. These changes in MAPK activation were paralleled by the increased production of PGE(2), TNF-alpha, IL-1beta, IL-6, and IL-10. Differential sensitivity to the inhibition of the MAPK pathways was observed with regard to the mediator evaluated and the presence or absence of burn injury. In general cytokine production in the burn group was in part resistant to the inhibition of a single MAPK pathway as compared with shams. Thus, burn injury increases cross-talk between the MAPKs pathways, suggesting that alterations MAPK activation and signal transduction contribute to the development Mphi hyperactivity post-injury.
Insights
Thermal injury causes macrophage hyperactivity by altering mitogen-activated protein kinase (MAPK) pathways. These changes in signal transduction contribute to immune suppression and organ failure after burns.
Area of Science:
- Immunology
- Cellular Biology
- Trauma Research
Background:
- Thermal injury induces macrophage hyperactivity, leading to inflammatory mediator release.
- This hyperactivity is implicated in immunosuppression, sepsis, and multiple organ failure post-burn.
- The specific signal transduction pathways driving macrophage hyperactivity after burns are not fully understood.
Purpose of the Study:
- To investigate the role of mitogen-activated protein kinase (MAPK) pathways in macrophage hyperactivity following thermal injury.
- To determine how burn injury affects LPS-stimulated inflammatory mediator production and MAPK activation in macrophages.
Main Methods:
- C57BL/6 female mice were subjected to a 25% total body surface area (TBSA) burn.
- Splenic macrophages were isolated 7 days post-burn.
- LPS-stimulated inflammatory mediator production and MAPK (p38, ERK1/2, JNK) activation were measured.
Main Results:
- Burn injury enhanced LPS-induced p38 MAPK activation and suppressed JNK activation; ERK1/2 activation remained unchanged.
- Increased production of PGE(2), TNF-alpha, IL-1beta, IL-6, and IL-10 was observed.
- Macrophage cytokine production in burn-injured mice showed partial resistance to single MAPK pathway inhibition, indicating pathway cross-talk.
Conclusions:
- Burn injury alters MAPK pathway activation and signal transduction, contributing to macrophage hyperactivity.
- Increased cross-talk between MAPK pathways post-burn may underlie the heightened inflammatory response.
- Understanding these pathways is crucial for developing therapeutic strategies for post-burn complications.
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