Low STAT3 expression sensitizes to toxic effects of β-adrenergic receptor stimulation in peripartum cardiomyopathy

Area of Science:

• Cardiology
• Molecular Biology
• Genetics

Background:

• Peripartum cardiomyopathy (PPCM) is a form of heart failure with controversial treatment options.
• Reduced cardiac STAT3 expression is observed in PPCM patients.
• STAT3 deficiency in cardiomyocytes leads to PPCM-like conditions in mice.

Purpose of the Study:

• To investigate the role of STAT3-dependent signaling in the response to beta-adrenergic receptor (β-AR) agonists in PPCM.
• To analyze the effects of dobutamine, a β1-AR agonist, on cardiac function in PPCM.

Main Methods:

• Analysis of STAT3-deficient (CKO) mice and human PPCM patient data.
• Administration of β-AR agonists (dobutamine, isoproterenol) and blockers (metoprolol) in mouse models.
• Assessment of cardiac function, metabolism (triglyceride, pyruvate, lactate), and molecular signaling pathways (microRNAs, insulin/glucose transporter-4, neuregulin/ErbB).

Main Results:

• In severe PPCM patients, dobutamine was associated with heart transplantation or mechanical support, while non-dobutamine treatment improved function.
• Isoproterenol induced severe heart failure and mortality in STAT3-deficient mice by impairing fatty acid and glucose uptake, causing metabolic deficit.
• STAT3 deficiency disrupted key signaling pathways, leading to energy depletion, oxidative stress, and cardiomyocyte loss.

Conclusions:

• Beta-1 adrenergic receptor stimulation impairs glucose uptake and energy metabolism in STAT3-deficient cardiomyocytes, potentially causing irreversible heart failure.
• These findings suggest that dobutamine may exacerbate heart failure in PPCM patients with reduced STAT3 expression.
• Metoprolol or glucose-uptake-promoting drugs may offer therapeutic benefits in such cases.