Load-dependent and -independent regulation of proinflammatory cytokine and cytokine receptor gene expression in the...

Area of Science:

• Cardiovascular Physiology
• Molecular Biology
• Immunology

Background:

• Previous research focused on acute hemodynamic pressure overload effects on proinflammatory cytokine gene expression.
• The impact of sustained hemodynamic overloading on these pathways remains largely unexamined.

Purpose of the Study:

• To investigate the effects of sustained hemodynamic pressure overload on proinflammatory cytokine and cytokine receptor gene expression in the heart.
• To elucidate the mechanisms regulating these changes in response to chronic pressure overload.

Main Methods:

• Sustained hemodynamic pressure overload was induced in mice via transverse aortic constriction.
• Gene expression of proinflammatory cytokines (TNF, IL-1beta, IL-6) and their receptors was quantified using ribonuclease protection assays (RPA).
• Left ventricular structure and function were assessed using M-mode echocardiography.

Main Results:

• Proinflammatory cytokine mRNA levels (TNF, IL-1beta, IL-6) peaked at 6 hours post-constriction and normalized within 72 hours.
• Significant increases were observed in interleukin-1 receptor type II (IL-1RII) and IL-6 receptor alpha (IL-6Ralpha) mRNA.
• Tristetraprolin, an mRNA-destabilizing protein, expression increased, potentially contributing to the transient cytokine response.

Conclusions:

• Sustained hemodynamic overloading induces a transient upregulation of proinflammatory cytokine and receptor gene expression in the heart.
• The observed decrease in cytokine expression, despite persistent overload, suggests regulation by both load-dependent and load-independent mechanisms.