Lipopolysaccharide induces upregulation of neutral endopeptidase 24.11 on human neutrophils: involvement of the CD14 receptor.
1. As lipopolysaccharide is a major stimulator of neutrophil responses during Gram-negative bacterial infections, we studied its effect on the membrane expression of neutral endopeptidase 24.11/CD10 on neutrophils in a model of endotoxaemia in vitro. Lipopolysaccharide added to human whole-blood induced a marked and sustained CD10/neutral endopeptidase upregulation that was already detectable at 0.1 ng/ml and was maximal at a lipopolysaccharide concentration of 10 ng/ml. 2. We observed that neither tumour necrosis factor-alpha nor any newly synthesized protein was involved in the upregulation observed after 1 h incubation with 10 ng/ml lipopolysaccharide. 3. We further studied whether the lipopolysaccharide-induced CD10/neutral endopeptidase upregulation was mediated by lipopolysaccharide binding to the neutrophil CD14 receptor. Incubation of whole blood with an anti-CD14 monoclonal antibody before the addition of 0.1 ng/ml or 0.5 ng/ml lipopolysaccharide resulted in complete inhibition of CD10/neutral endopeptidase upregulation. In contrast, at a lipopolysaccharide concentration of 10 ng/ml, the anti-CD14 monoclonal antibody had an incomplete blocking effect. 4. The differential requirement for the CD14 receptor, depending on the lipopolysaccharide dose, was confirmed by the study of a patient suffering from paroxysmal nocturnal haemoglobinuria (in whom a complete defect in neutrophil CD14 expression was previously documented). 5. We finally confirmed these results using purified neutrophils, demonstrating that lipopolysaccharide-induced CD10/neutral endopeptidase upregulation depends on direct interaction with neutrophil CD14.
Fagny
C
C
Laboratoire Pluridisciplinaire de Recherche Expérimentale Biomédicale, Faculté de Médecine, Brussels, Belgium.
Marchant
A
A
De Prez
E
E
Goldman
M
M
Deschodt-Lanckman
M
M
D015703:Antigens, CD / Q000502:physiology*; D015214:Antigens, Differentiation, Myelomonocytic / Q000502:physiology*; D002478:Cells, Cultured; D016207:Cytokines / Q000494:pharmacology; D004926:Escherichia coli; D006457:Hemoglobinuria, Paroxysmal / Q000097:blood; D006801:Humans; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides / Q000494:pharmacology*; D015260:Neprilysin / Q000096:biosynthesis*; D009504:Neutrophils / Q000201:enzymology* / Q000276:immunology; D011994:Recombinant Proteins / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects*
D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D016207:Cytokines; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D011994:Recombinant Proteins; D015260:Neprilysin