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Mediators of Inflammation
Volume 2013, Article ID 824919, 12 pages
http://dx.doi.org/10.1155/2013/824919
Research Article

CD14 Mediates Binding of High Doses of LPS but Is Dispensable for TNF-α Production

1Department of Cell Biology, Nencki Institute of Experimental Biology, 3 Pasteur Street, 02-093 Warsaw, Poland
2Ridgeview Instruments AB, Skillsta 4, 740 20 Vänge, Sweden
3Biomedical Radiation Sciences, Department of Radiology, Oncology and Radiation Sciences, Uppsala University, Dag Hammarskjölds väg 20, 751 85 Uppsala, Sweden

Received 30 June 2013; Revised 29 August 2013; Accepted 11 October 2013

Academic Editor: Linda Burkly

Copyright © 2013 Kinga Borzęcka et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

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.