M1 to M2 macrophage polarization in heparin-binding epidermal growth factor-like growth factor therapy for necrotizing enterocolitis.
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.


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.
The 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.
Jia
J
Wei
The 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. Electronic address: gail.besner@nationwidechildrens.org.
Gail E
GE
Besner
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015415:Biomarkers / Q000378:metabolism; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D002460:Cell Line; D020345:Enterocolitis, Necrotizing / Q000188:drug therapy* / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D005260:Female; D005434:Flow Cytometry; D066257:Heparin-binding EGF-like Growth Factor / Q000494:pharmacology / Q000627:therapeutic use*; D006801:Humans; D007413:Intestinal Mucosa / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D020011:Protective Agents / Q000494:pharmacology / Q000627:therapeutic use*; D011897:Random Allocation; D060888:Real-Time Polymerase Chain Reaction; D016896:Treatment Outcome
D015415:Biomarkers; D066257:Heparin-binding EGF-like Growth Factor; D020011:Protective Agents; D053148:Caspase 3
Heparin-binding EGF-like growth factor (HB-EGF); Macrophage polarization; Necrotizing enterocolitis