How are cytokines activated in heart failure?

Area of Science:

• Cardiology
• Molecular Biology
• Pathophysiology

Background:

• Elevated left ventricular (LV) end-diastolic wall stress is a hallmark of dilated and failing hearts.
• This stress triggers myocardial expression of cytokines, impacting LV contractile function and remodeling.
• Cytokine diffusion into coronary effluent is limited, suggesting myocardial production has minimal impact on plasma levels.

Purpose of the Study:

• To investigate the source of elevated plasma cytokine levels in heart failure.
• To understand the interplay between myocardial stress, cytokine production, and systemic inflammation in cardiac dysfunction.

Main Methods:

• Analysis of cytokine expression in myocardial tissue.
• Assessment of cytokine diffusion in coronary effluent.
• Correlation of plasma cytokine levels with indicators of tissue perfusion and hypoxia.
• Evaluation of the role of bacterial endotoxins.

Main Results:

• Myocardial expression of cytokines is induced by elevated LV wall stress.
• Limited diffusion of these cytokines into the coronary effluent.
• Raised plasma cytokine levels are predominantly attributed to extramyocardial sources.
• Altered tissue perfusion, hypoxia, and potential bacterial endotoxin release contribute to extramyocardial cytokine production.

Conclusions:

• In heart failure, extramyocardial cytokine production, driven by factors like tissue hypoxia and endotoxemia, is the primary cause of elevated plasma cytokine levels.
• Myocardial cytokine production plays a minor role in systemic inflammation in this context.
• Targeting extramyocardial sources may be crucial for managing inflammation in heart failure.