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Depletion and Reconstitution of Macrophages in Mice
Published on: August 1, 2012
Exosomal miR-148a-3p from LPS-Activated Macrophages Promotes M1 Polarization and Ferroptosis-Related Characteristics
Jun Liang1,2, Yingli Cai1,2, Yiming Shao3
1Clinical Medical College, Jinan University, Guangzhou, Guangdong, 510632, People's Republic of China.
Background:
Gram-negative bacterial infection is a major cause of severe inflammatory disorders and cellular damage, with lipopolysaccharide (LPS) as a key pathogenic trigger. Macrophages are central players in LPS-induced inflammatory cascades, yet the mechanisms by which macrophage-derived exosomes propagate inflammatory signals and cellular injury remain elusive. This study aimed to investigate whether LPS-activated macrophage exosomes drive M1 polarization and ferroptosis-related characteristics in recipient macrophages.
Methods:
RAW264.7 macrophages were treated with LPS. Exosomes were extracted through ultracentrifugation and their characteristics were determined utilizing Western blot, transmission electron microscopy, and nanoparticle tracking analysis. MicroRNA levels were quantified by droplet digital PCR. The functional effects of exosomes and miR-148a-3p inhibitor on recipient macrophages were evaluated via quantitative real-time PCR, Western blot, enzyme-linked immunosorbent assay, malondialdehyde (MDA) detection and ferrostatin-1 (Fer-1) rescue assay. Dual-luciferase reporter assay validated direct targeting relationships.
Results:
LPS directly induced M1 polarization and pro-inflammatory cytokine secretion in RAW264.7 cells. Exosomes from LPS-stimulated macrophages were enriched with miR-148a-3p and promoted M1 polarization and ferroptosis-related characteristics in recipient cells. Inhibition of miR-148a-3p and Fer-1 treatment effectively negated the LPS-exosome-mediated effects. Mechanistically, miR-148a-3p directly interacted with and inhibited SLC7A11.
Conclusion:
Exosomal miR-148a-3p derived from LPS-activated macrophages promotes M1 polarization and ferroptosis-related characteristics in recipient macrophages by reducing SLC7A11. This finding uncovers a novel LPS-induced inflammatory signaling pathway in macrophage-macrophage communication and suggests a potential candidate target for intervention in Gram-negative bacteria-related inflammatory injury.
Insights
Exosomes from lipopolysaccharide (LPS)-activated macrophages, enriched with miR-148a-3p, promote M1 polarization and ferroptosis in recipient macrophages. This highlights a novel inflammatory pathway and potential therapeutic target for Gram-negative bacterial infections.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- Gram-negative bacterial infections trigger severe inflammation and cellular damage, with lipopolysaccharide (LPS) as a key factor.
- Macrophages are central to LPS-induced inflammation, but how their exosomes spread inflammatory signals and cause injury is unclear.
- This study investigates if exosomes from LPS-activated macrophages induce M1 polarization and ferroptosis in other macrophages.
Purpose of the Study:
- To determine if exosomes from LPS-stimulated macrophages promote M1 polarization and ferroptosis in recipient macrophages.
- To elucidate the role of exosomal miR-148a-3p in mediating these effects.
- To identify the molecular mechanism, specifically the interaction between miR-148a-3p and SLC7A11.
Main Methods:
- RAW264.7 macrophages were stimulated with LPS.
- Exosomes were isolated via ultracentrifugation and characterized (Western blot, TEM, NTA).
- MicroRNA levels, exosome function, M1 polarization, ferroptosis markers, and miR-148a-3p targeting of SLC7A11 were assessed.
Main Results:
- LPS induced M1 polarization and pro-inflammatory cytokine secretion in RAW264.7 cells.
- Exosomes from LPS-stimulated macrophages contained higher miR-148a-3p and promoted M1 polarization and ferroptosis in recipient cells.
- Inhibiting miR-148a-3p or blocking ferroptosis reversed these effects; miR-148a-3p directly targeted and inhibited SLC7A11.
Conclusions:
- Exosomal miR-148a-3p from LPS-activated macrophages drives M1 polarization and ferroptosis in recipient cells by downregulating SLC7A11.
- This reveals a novel macrophage-to-macrophage inflammatory signaling pathway mediated by exosomes.
- The findings suggest exosomal miR-148a-3p as a potential therapeutic target for LPS-induced inflammatory injury.
