Macrophage migration inhibitory factor induces cardiomyocyte apoptosis

Area of Science:

• Cardiology
• Molecular Biology
• Immunology

Background:

• Macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine implicated in cardiac dysfunction.
• Inhibition of MIF has shown promise in improving cardiac function in sepsis models.

Purpose of the Study:

• To investigate if MIF-induced cardiac contractile dysfunction involves myocyte apoptosis.
• To identify intracellular signaling pathways activated by MIF in cardiomyocytes.

Main Methods:

• Primary cardiomyocyte cultures were treated with MIF (20 and 30 ng/ml) for 24 hours.
• Apoptosis was assessed using TUNEL staining.
• Caspase 3 cleavage, Bcl-xL/Bax ratios, and stress kinase phosphorylation (p38MAPK, JNK) were analyzed.
• The chemical inhibitor ISO-1 was used to inactivate MIF.

Main Results:

• MIF treatment dose-dependently increased cardiomyocyte apoptosis (from 3.7% in controls to 15.5% and 26.0%).
• ISO-1 significantly attenuated MIF-induced apoptosis, caspase 3 cleavage, and altered Bcl-xL/Bax ratios.
• MIF rapidly induced phosphorylation of p38MAPK and JNK stress kinases.

Conclusions:

• MIF induces cardiomyocyte apoptosis via activation of stress kinases and mitochondria-dependent pathways.
• Inactivation of MIF's pro-inflammatory activity enhances cardiomyocyte survival and function.