Phosphatidylcholine Liposomes Reprogram Macrophages toward an Inflammatory Phenotype

Area of Science:

• Cell Biology
• Immunology
• Biochemistry

Background:

• Phospholipids are fundamental to cellular membranes and vesicles like exosomes.
• Artificial lipid nanoparticles utilize phospholipids for cargo encapsulation and delivery.
• The impact of vesicle phospholipids on cellular physiology is often underestimated.

Purpose of the Study:

• To investigate the physiological effects of phospholipids within liposomes on cellular function.
• To determine how palmitoyl oleoyl phosphatidylcholine (POPC) liposomes alter macrophage gene expression and pathways.

Main Methods:

• In vivo and in vitro exposure of macrophages to POPC liposomes.
• Differential gene expression analysis (transcriptomics).
• Signaling pathway impact analysis.
• Proteomic analysis using mass spectrometry.
• Flow cytometry for neutrophil recruitment assessment.

Main Results:

• POPC liposomes induced significant changes in 1598 genes in macrophages.
• Activation of inflammatory pathways, including NF-κB, with increased cytokine and chemokine expression.
• Proteomic analysis revealed altered protein expression, notably impacting neutrophil degranulation.
• Rapid neutrophil recruitment to the peritoneal cavity observed post-POPC liposome exposure.

Conclusions:

• Phospholipids within vesicles, specifically POPC, can profoundly modulate cellular functions.
• POPC liposomes trigger significant transcriptomic and proteomic alterations in macrophages.
• These findings highlight the critical role of vesicle composition in cellular responses and inflammation.