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Complement system activation in cardiac and skeletal muscle pathology: friend or foe?
Msaro Syriga1, Manolis Mavroidis
1Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens 11527, Greece.
Insights
Complement inhibition shows promise for heart attack recovery, but modulating its activity, not blocking it, may be key for ischemia. Combined treatments targeting multiple pathways are likely optimal.
Area of Science:
- Cardiology
- Immunology
- Cellular Biology
Background:
- Acute myocardial infarction (AMI) necessitates strategies to minimize heart muscle damage and enhance repair.
- Innate immunity, particularly complement activation, plays a complex role in cardiac ischemia/reperfusion injury.
- While animal studies suggest complement inhibition is protective, clinical trials in AMI have yielded disappointing results.
Purpose of the Study:
- To explore the dual role of complement activation in myocardial infarction.
- To evaluate the potential of complement modulation as a therapeutic strategy for AMI.
- To identify optimal treatment approaches for post-myocardial infarction cardiac repair.
Main Methods:
- Review of experimental data from animal models of cardiac ischemia/reperfusion.
- Analysis of clinical trial outcomes for complement inhibitors in AMI patients.
- Examination of the beneficial roles of complement in tissue repair and regeneration.
Main Results:
- Inhibition of complement activation protects cardiac tissue in experimental models.
- Clinical studies with complement inhibitors (e.g., C5 inhibitors) in AMI have largely failed.
- Complement's role varies: beneficial when inhibiting initial cell destruction (autoimmune conditions) but potentially detrimental when recruited by dying cells (ischemia).
Conclusions:
- Simply blocking complement activation may not be effective for ischemia-related myocardial injury.
- Modulating complement activity, rather than complete inhibition, might be a more suitable therapeutic approach.
- Successful treatment of AMI likely requires combination therapies targeting multiple interconnected signaling pathways, with complement modulation as a potential component.
Abstract:
A major goal in current cardiology practice is to determine optimal strategies for minimizing myocardial necrosis and optimizing cardiac repair following an acute myocardial infarction. Temporally regulated activation and suppression of innate immunity may be critical for achieving this goal. Extensive experimental data in various animal models have indicated that inhibiting complement activation offers protection to cardiac tissue after ischemia/reperfusion. However, the results of clinical studies using complement inhibitors (mainly at the C5 level) in patients with acute myocardial infarction have largely been disappointing. In cases in which complement activation participates in the initial events of muscle cell destruction, as in autoimmune myocarditis or autoimmune muscle disorders, inhibition of complement activation is expected to prove a successful treatment. In other pathologic conditions in which complement is recruited by degenerating or dying muscle cells, as in ischemia, the ideal approach is probably to modulate rather than abruptly blunt complement activation. Beneficial effects of complement action with regard to waste disposal, recruitment of stem cells, regeneration, angiogenesis, and better utilization of energy sources under hypoxic conditions may also prove important for successful disease treatment. Patient outcome after myocardial infarction almost certainly depend upon the combined activation of several distinct but potentially interrelated signaling pathways, suggesting that a combination of treatments targeted to different pathways should be the therapy of choice, and modulation of complement could be one of them.
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