MFG-E8 released by apoptotic endothelial cells triggers anti-inflammatory macrophage reprogramming

Area of Science:

• Cardiovascular Biology
• Immunology
• Cellular Biology

Background:

• Endothelial cell apoptosis is a key part of the response to vascular injury.
• Atherosclerosis risk factors and immune insults induce endothelial cell apoptosis, but its effect on macrophages is unclear.

Purpose of the Study:

• To investigate the consequences of endothelial cell apoptosis on macrophage reprogramming.
• To identify the molecular mechanisms underlying this reprogramming.

Main Methods:

• Studied human and mouse endothelial cells undergoing apoptosis.
• Exposed macrophages to conditioned media from apoptotic endothelial cells and recombinant MFG-E8.
• Analyzed cytokine/chemokine secretion and STAT-3 phosphorylation.

Main Results:

• Apoptotic endothelial cells release milk fat globule-epidermal growth factor 8 (MFG-E8) in a caspase-3-dependent manner.
• MFG-E8 reprograms macrophages into an anti-inflammatory phenotype by increasing STAT-3 phosphorylation.
• Absence of MFG-E8 abrogates the anti-inflammatory reprogramming of macrophages.

Conclusions:

• Endothelial cell apoptosis triggers MFG-E8 release, which reprograms macrophages to an anti-inflammatory state.
• MFG-E8 plays a crucial role in mediating the anti-inflammatory effects of the apoptotic microenvironment on macrophages.
• This pathway is important for understanding anti-inflammatory responses in vascular diseases.