Background: The proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) has been implicated in the pathogenesis of congestive heart failure. Recent studies have shown that adenosine inhibits lipopolysaccharide (LPS)-induced expression of TNF-alpha in macrophages and rat cardiomyocytes. The aim of this study was to determine whether adenosine has a similar effect in the failing human heart.
Methods and results: Left ventricular muscle strips were obtained from seven patients with end-stage congestive heart failure undergoing heart transplantation or insertion of a left ventricular assist device. The muscle strips were incubated at 37 degrees C in 95% O2/5% CO2 and stimulated with LPS (10 microg/mL). TNF-alpha release in the supernatant was measured with ELISA, and muscle sections were stained for TNF-alpha. Muscle strips released TNF-alpha in the absence of LPS (0.22+/-0.05 pg x mL(-1) x mg wet wt[-1]). TNF-alpha was immunolocalized to the cardiac myocyte, suggesting that the myocyte is a source for TNF-alpha production. Adenosine (10 micromol/L) decreased TNF-alpha by 40% (P<.05). The selective adenosine A2 receptor agonist DPMA (10 micromol/L) decreased TNF-alpha release by 87% (P<.001), whereas ITu (10 micromol/L), an adenosine-regulating agent that increases endogenous adenosine concentration, inhibited TNF-alpha release by 93% (P<.001).
Conclusions: Adenosine can significantly diminish TNF levels in the failing human heart and may represent a new pharmacological intervention in congestive heart failure.