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Depletion and Reconstitution of Macrophages in Mice
Published on: August 1, 2012
MFG-E8-Derived Oligopeptide MOP3 Facilitates Anti-Inflammatory M2-like Macrophage Polarization in Gut
Russell Hollis1,2,3, Yuichi Akama1, Yongchan Lee1
1Center for Immunology and Inflammation, The Feinstein Institutes for Medical Research, Manhasset, NY 11030, USA.
Abstract:
Gut ischemia/reperfusion (I/R) injury releases damage-associated molecular patterns (DAMPs), such as extracellular cold-inducible RNA-binding protein (eCIRP). Milk fat globule-epidermal growth factor VIII-derived oligopeptide 3 (MOP3) is a novel peptide enabling macrophage uptake of eCIRP via αvβ3-integrin. MOP3 reduces inflammation in gut I/R, but its mechanisms are not completely understood. We hypothesized MOP3 promotes macrophage polarization toward an anti-inflammatory, M2-like phenotype in gut I/R. We induced gut I/R in mice through 60 min of superior mesenteric artery occlusion followed by 4 h of reperfusion. Intestines were evaluated for macrophage polarization by flow cytometry and immunofluorescence histology. Peritoneal cavity macrophages were isolated from mice and treated with eCIRP, MOP3, αvβ3-antibody, and/or naïve IgG for 4 or 24 h. Polarity was assessed by flow cytometry, qPCR, and ELISA. Compared to the sham, the M2 proportion after gut I/R decreased by 22.7%, and the M1 proportion increased by 241%. MOP3 treatment increased the M2 proportion by 64.3%, and the M1 proportion decreased by 22.7%. In eCIRP-stimulated macrophages, MOP3 treatment increased M2-like and reduced M1-like cell-surface markers, gene expression, and cytokine levels. αvβ3 antibody dramatically reduced MOP3's effects. MOP3 promotes M2 polarization through αvβ3 integrin-mediated clearance of eCIRP, a novel mechanism whereby MOP3 reduces gut I/R injury.
Insights
Milk fat globule-epidermal growth factor VIII-derived oligopeptide 3 (MOP3) peptide promotes anti-inflammatory macrophage polarization in gut ischemia/reperfusion (I/R) injury. MOP3 utilizes the αvβ3 integrin to clear damage-associated molecular patterns (DAMPs), reducing gut I/R inflammation.
Area of Science:
- Immunology
- Gastroenterology
- Molecular Biology
Background:
- Gut ischemia/reperfusion (I/R) injury triggers inflammation via damage-associated molecular patterns (DAMPs), notably extracellular cold-inducible RNA-binding protein (eCIRP).
- Macrophage polarization plays a critical role in modulating the inflammatory response during I/R injury, with M1 phenotypes promoting inflammation and M2 phenotypes mediating resolution.
Purpose of the Study:
- To investigate the mechanism by which milk fat globule-epidermal growth factor VIII-derived oligopeptide 3 (MOP3) reduces gut I/R injury.
- To determine if MOP3 promotes macrophage polarization towards an anti-inflammatory M2 phenotype in the context of gut I/R.
Main Methods:
- Gut I/R injury was induced in mice. Macrophage polarization was assessed in vivo using flow cytometry and immunofluorescence.
- Peritoneal macrophages were isolated and treated with eCIRP and/or MOP3 in vitro. Polarization markers, gene expression, and cytokine levels were analyzed.
Main Results:
- Gut I/R significantly decreased the M2 macrophage proportion and increased the M1 proportion.
- MOP3 treatment reversed these effects, increasing M2 polarization and decreasing M1 polarization in vivo and in vitro.
- The effects of MOP3 were significantly diminished by an αvβ3 integrin antibody, indicating its crucial role in MOP3's mechanism.
Conclusions:
- MOP3 promotes M2 macrophage polarization, shifting the immune response towards an anti-inflammatory state in gut I/R injury.
- This M2 polarization is mediated through αvβ3 integrin-dependent clearance of eCIRP, representing a novel therapeutic mechanism for MOP3 in reducing gut I/R damage.
