CD14 mediates binding of high doses of LPS but is dispensable for TNF-α production.
Activation of macrophages with lipopolysaccharide (LPS) involves a sequential engagement of serum LPS-binding protein (LBP), plasma membrane CD14, and TLR4/MD-2 signaling complex. We analyzed participation of CD14 in TNF-α production stimulated with 1-1000 ng/mL of smooth or rough LPS (sLPS or rLPS) and in sLPS binding to RAW264 and J744 cells. CD14 was indispensable for TNF-α generation induced by a low concentration, 1 ng/mL, of sLPS and rLPS. At higher doses of both LPS forms (100-1000 ng/mL), TNF-α release required CD14 to much lower extent. Among the two forms of LPS, rLPS-induced TNF-α production was less CD14-dependent and could proceed in the absence of serum as an LBP source. On the other hand, the involvement of CD14 was crucial for the binding of 1000 ng/mL of sLPS judging from an inhibitory effect of the anti-CD14 antibody. The binding of sLPS was also strongly inhibited by dextran sulfate, a competitive ligand of scavenger receptors (SR). In the presence of dextran sulfate, sLPS-induced production of TNF-α was upregulated about 1.6-fold. The data indicate that CD14 together with SR participates in the binding of high doses of sLPS. However, CD14 contribution to TNF α production induced by high concentrations of sLPS and rLPS can be limited.
Department of Cell Biology, Nencki Institute of Experimental Biology, 3 Pasteur Street, 02-093 Warsaw, Poland.
Kinga
K
Borzęcka
Department of Cell Biology, Nencki Institute of Experimental Biology, 3 Pasteur Street, 02-093 Warsaw, Poland.
Agnieszka
A
Płóciennikowska
Ridgeview Instruments AB, Skillsta 4, 740 20 Vänge, Sweden ; Biomedical Radiation Sciences, Department of Radiology, Oncology and Radiation Sciences, Uppsala University, Dag Hammarskjölds väg 20, 751 85 Uppsala, Sweden.
Hanna
H
Björkelund
Department of Cell Biology, Nencki Institute of Experimental Biology, 3 Pasteur Street, 02-093 Warsaw, Poland.
Andrzej
A
Sobota
Department of Cell Biology, Nencki Institute of Experimental Biology, 3 Pasteur Street, 02-093 Warsaw, Poland.
Katarzyna
K
Kwiatkowska
D000209:Acute-Phase Proteins / Q000378:metabolism; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D018946:Chemokine CCL5 / Q000378:metabolism; D054426:Chemokine CXCL2 / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D005786:Gene Expression Regulation; D020868:Gene Silencing; D006801:Humans; D008024:Ligands; D018950:Lipopolysaccharide Receptors / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000737:chemistry*; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D011485:Protein Binding; D051116:Receptors, Scavenger / Q000378:metabolism; D015398:Signal Transduction; D051197:Toll-Like Receptor 4 / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D000099231:Lipopolysaccharide-Binding Protein
D000209:Acute-Phase Proteins; D002352:Carrier Proteins; D018946:Chemokine CCL5; D054426:Chemokine CXCL2; D008024:Ligands; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D051116:Receptors, Scavenger; D051197:Toll-Like Receptor 4; D014409:Tumor Necrosis Factor-alpha; D000099231:Lipopolysaccharide-Binding Protein; C404915:Cxcl2 protein, mouse; C493487:Tlr4 protein, mouse