Objective: The inflammatory process is associated with cardiac diastolic dysfunction, which has been demonstrated to be an independent prognostic marker for the mortality of critically ill patients. We investigated the association among inflammatory cytokines (tumor necrosis factor-α and interleukin-6), diastolic heart failure, and the possible molecular mechanism.
Design: Prospective case-controlled cohort and molecular studies.
Setting: University hospital and research laboratory.
Subjects: Patients with a diagnosis of diastolic heart failure by echocardiography and matched control subjects from the general population (study group 1) and also subjects from the intensive care unit (study group 2). Sarcoplasmic reticulum Ca2+-ATPase (SERCA2) gene expression and diastolic calcium decay in HL-1 cardiomyocytes were used as molecular phenotypes of diastolic heart failure.
Interventions: Soluble plasma levels of tumor necrosis factor-α and interleukin-6 were measured in all subjects. An approximate 1.75-kb promoter of the SERCA2 gene was cloned to the pGL3 luciferase reporter. The effect of tumor necrosis factor-α and interleukin-6 on SERCA2 gene expression and diastolic calcium decay of HL-1 cardiomyocytes were investigated.
Measurements and main results: Patients with diastolic heart failure had significantly higher plasma levels of tumor necrosis factor-α and interleukin-6 than the control subjects. Significant correlations (p < .01 for each) were found for tumor necrosis factor-α and E/Em (r = .87) and E/A (r = -0.69), and for interleukin-6 and E/Em (r = .80) and E/A (r = -0.65). Cytokine levels were also correlated with diastolic function in critically ill patients (study group 2), and diastolic function improved significantly in association with decrease of cytokines. Tumor necrosis factor-α, interleukin-6, and sera from critically ill patients downregulated the expression of the SERCA2 gene. Tumor necrosis factor-α and interleukin-6 also delayed the diastolic calcium reuptake and decay in cardiomyocytes.
Conclusions: Through downregulation of SERCA2 gene expression, inflammatory cytokines may cause cardiac diastolic dysfunction by decreasing diastolic calcium reuptake. Our study may suggest novel therapeutic strategies for diastolic heart failure and critically ill patients by modulating inflammatory reactions.