Milk fat globule epidermal growth factor-factor VIII is down-regulated in sepsis via the lipopolysaccharide-CD14 pathway.
Phagocytosis prevents the release of potentially harmful or immunogenic materials from dying cells. Milk fat globule epidermal growth factor (EGF)-factor VIII (MFG-E8) mediates the clearance of apoptotic cells. We have previously shown that the administration of MFG-E8-rich exosomes from immature dendritic cells promotes the phagocytosis of apoptotic cells and improves survival in sepsis. Because endotoxin is elevated in polymicrobial sepsis, we hypothesized that down-regulation of MFG-E8 is mediated via the LPS-CD14 pathway, eventually leading to the accruement of apoptotic cells. Polymicrobial sepsis was induced by cecal ligation and puncture (CLP) in CD14-deficient (CD14(-/-)), TLR4-mutated and wild-type (WT) mice. In addition, endotoxemia was elicited by i.p. injection of LPS. LPS was also neutralized by pretreating CLP-induced WT mice with polymyxin B. Splenic MFG-E8 expression, phagocytic activity, and apoptosis were assessed 5 and 20 h after CLP or 5 h after LPS administration. In septic WT mice, MFG-E8 mRNA and protein levels were suppressed by 49 and 33%, respectively. Endotoxemia reduced MFG-E8 mRNA expression in a dose dependent manner and the down-regulation of MFG-E8 mRNA expression in CLP-induced sepsis was attenuated by polymyxin B. This CLP-induced suppression was not observed in both CD14(-/-) and TLR4-mutated mice. CLP significantly decreased phagocytic activity of peritoneal macrophages in WT (by 30%), but not in CD14(-/-) mice. CLP also induced significant apoptosis in the spleen of WT (by 61%), but less in CD14(-/-) mice. Thus, MFG-E8 production is down-regulated in sepsis by LPS-CD14 dependent fashion, leading to a reduction of phagocytosis of apoptotic cells.
Komura
Hidefumi
H
Department of Surgery, North Shore University Hospital and The Feinstein Institute for Medical Research, Manhasset, NY 11030, USA.
Miksa
Michael
M
Wu
Rongqian
R
Goyert
Sanna M
SM
Wang
Ping
P
D000818:Animals; D000954:Antigens, Surface / Q000096:biosynthesis / Q000235:genetics; D017209:Apoptosis / Q000276:immunology; D004306:Dose-Response Relationship, Immunologic; D015536:Down-Regulation / Q000235:genetics / Q000276:immunology*; D019446:Endotoxemia / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D018950:Lipopolysaccharide Receptors / Q000235:genetics / Q000502:physiology*; D008070:Lipopolysaccharides / Q000502:physiology*; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D018345:Mice, Knockout; D008817:Mice, Mutant Strains; D008894:Milk Proteins / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics; D010587:Phagocytosis / Q000235:genetics / Q000276:immunology; D012333:RNA, Messenger / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology*; D013154:Spleen / Q000276:immunology / Q000378:metabolism / Q000473:pathology
D000954:Antigens, Surface; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; C490919:Mfge8 protein, mouse; D008894:Milk Proteins; D012333:RNA, Messenger