Pericardial Fluid Accumulates microRNAs That Regulate Heart Fibrosis after Myocardial Infarction

Area of Science:

• Cardiovascular Biology
• Molecular Cardiology
• Biomarker Discovery

Background:

• Pericardial fluid (PF) contains molecular targets for myocardial infarction (MI) repair.
• MicroRNAs (miRs) are key regulators of cardiac pathological responses post-MI.

Purpose of the Study:

• To analyze the microRNA content of pericardial fluid after MI.
• To investigate the role of PF microRNAs in cardiac fibrosis and fibroblast activation.

Main Methods:

• Collected PF from ST-segment elevation MI (STEMI), non-ST-segment elevation MI (NSTEMI), and control patients during coronary artery bypass grafting (CABG).
• Performed small RNA sequencing on PF to profile microRNA content.
• Assessed the biological effects of PF on human cardiac fibroblasts in vitro.

Main Results:

• PF accumulates fibrotic and inflammatory molecules, including soluble suppression of tumorigenicity 2 (ST-2), in STEMI patients, inversely correlating with left ventricle ejection fraction.
• PF from STEMI patients is enriched in both pro-fibrotic and anti-fibrotic microRNAs.
• miR-22-3p was identified as inhibiting transforming growth factor-beta (TGF-β)-induced human cardiac fibroblast activation in vitro.

Conclusions:

• Pericardial fluid is a promising source for identifying diagnostic/prognostic microRNAs after myocardial infarction.
• PF analysis can reveal novel therapeutic targets for managing cardiac fibrosis.