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Updated: Apr 14, 2026
Polarization and Characterization of M1 and M2 Human Monocyte-Derived Macrophages on Implant Surfaces
Published on: December 6, 2024
M1 to M2 macrophage polarization in heparin-binding epidermal growth factor-like growth factor therapy for
1The Research Institute at Nationwide Children's Hospital, Center for Perinatal Research, Department of Pediatric Surgery, Nationwide Children's Hospital, The Ohio State University College of Medicine, Columbus, Ohio.
Background:
Macrophages can be polarized into proinflammatory (M1) and anti-inflammatory (M2) subtypes. However, whether macrophage polarization plays a role in necrotizing enterocolitis (NEC) remains unknown.
Materials And Methods:
Macrophages were derived from the THP-1 human monocyte cell line. Apoptosis of human fetal small intestinal epithelial FHs-74 cells was determined by Annexin V/propidium iodide flow cytometry and by Western blotting to detect cleaved caspase-3. The effect of heparin-binding epidermal growth factor-like growth factor (HB-EGF) on macrophage polarization was determined by flow cytometry with M1/M2 markers and real time polymerase chain reaction. In vivo, experimental NEC was induced in mouse pups by repeated exposure to hypoxia, hypothermia, and hypertonic feedings. Intestinal histologic sections were subjected to immunohistochemical staining for the detection of M1 and M2 macrophages.
Results:
In vitro, FHs-74 cell apoptosis was increased after coculture with macrophages and lipopolysaccharide (LPS). This apoptosis was increased by exposure to M1-conditioned medium and suppressed by exposure to M2-conditioned medium. HB-EGF significantly decreased LPS-induced M1 polarization and promoted M2 polarization via signal transducers and activators of transcription 3 activation. Addition of HB-EGF to LPS-stimulated macrophages suppressed the proapoptotic effects of the macrophages on FHs-74 cells. In vivo, we found enhanced intestinal macrophage infiltration in pups subjected to NEC, most of which were M1 macrophages. HB-EGF treatment of pups subjected to experimental NEC significantly reduced M1 and increased M2 polarization and protected the intestines from NEC.
Conclusions:
M1 macrophages promote NEC by increasing intestinal epithelial apoptosis. HB-EGF protects the intestines from NEC by preventing M1 and promoting M2 polarization.
Insights
Proinflammatory M1 macrophages worsen necrotizing enterocolitis (NEC) by increasing intestinal cell death. Heparin-binding epidermal growth factor-like growth factor (HB-EGF) protects against NEC by shifting macrophages to an anti-inflammatory M2 state.
Area of Science:
- Immunology
- Gastroenterology
- Neonatal Research
Background:
- Macrophages exhibit proinflammatory (M1) and anti-inflammatory (M2) phenotypes.
- The role of macrophage polarization in necrotizing enterocolitis (NEC) is currently unknown.
Purpose of the Study:
- To investigate the role of macrophage polarization in NEC.
- To determine the effect of heparin-binding epidermal growth factor-like growth factor (HB-EGF) on macrophage polarization and NEC.
Main Methods:
- Macrophage polarization was assessed in vitro using M1/M2 markers and in vivo via immunohistochemistry in a mouse model of NEC.
- FHs-74 cell apoptosis was measured by flow cytometry and Western blotting.
- HB-EGF's effect on polarization and apoptosis was evaluated.
Main Results:
- M1-conditioned medium increased FHs-74 cell apoptosis, while M2-conditioned medium suppressed it.
- HB-EGF inhibited M1 polarization and promoted M2 polarization in macrophages, reducing epithelial cell apoptosis.
- In vivo, NEC pups showed increased M1 macrophage infiltration; HB-EGF treatment reduced M1, increased M2 polarization, and conferred intestinal protection.
Conclusions:
- M1 macrophages exacerbate NEC by inducing intestinal epithelial apoptosis.
- HB-EGF demonstrates a protective effect against NEC by modulating macrophage polarization from M1 to M2.
