Early accumulation of the terminal complement-complex in the ischaemic myocardium after reperfusion

Area of Science:

• Cardiovascular Research
• Immunology
• Pathology

Background:

• The terminal complement complex C5b-9 (also known as the membrane attack complex) is implicated in tissue damage.
• Its accumulation in infarcted myocardium suggests a role in myocardial infarction pathogenesis.

Purpose of the Study:

• To investigate the time course of C5b-9 deposition in experimental myocardial infarction.
• To determine the influence of reperfusion on C5b-9 accumulation in the infarcted heart.

Main Methods:

• Experimental myocardial infarction was induced in rabbits by coronary artery occlusion.
• Groups were subjected to either prolonged occlusion without reperfusion or shorter occlusion followed by reperfusion.
• C5b-9 deposition was quantified using immunohistochemistry and ELISA on myocardial biopsies.

Main Results:

• In the absence of reperfusion, C5b-9 accumulation was a late event, observed after 5-6 hours of ischemia.
• In the presence of reperfusion, significant C5b-9 deposition was detected as early as 30 minutes after ischemia onset.
• This indicates reperfusion accelerates C5b-9 deposition in ischemic myocardium.

Conclusions:

• C5b-9 accumulation occurs late in myocardial infarction when tissue is largely necrotic if reperfusion is absent.
• Rapid C5b-9 deposition during ischemia-reperfusion suggests the complement system activation plays a significant role in reperfusion injury.
• These findings highlight the complement system's involvement in the pathophysiology of myocardial infarction and reperfusion injury.