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Blood, 15 February 2008, Vol. 111, No. 4, pp. 2122-2131. Prepublished online as a Blood First Edition Paper on December 4, 2007; DOI 10.1182/blood-2007-06-097782. This Article Full Text Full Text (PDF) All Versions of this Article: blood-2007-06-097782v1 111/4/2122    most recent Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Rights and Permissions Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Google Scholar Articles by Tissières, P. Articles by Pugin, J. PubMed PubMed Citation Articles by Tissières, P. Articles by Pugin, J. Related Collections Immunobiology Social Bookmarking                   What's this?  Previous Article  |  Table of Contents  |  Next Article  IMMUNOBIOLOGY Soluble MD-2 is an acute-phase protein and an opsonin for Gram-negative bacteria Pierre Tissières1, Irène Dunn-Siegrist1, Michela Schäppi2, Greg Elson3, Rachel Comte1, Vandack Nobre1, and Jérôme Pugin1 1 Intensive Care, Department of Anesthesiology, Pharmacology and Intensive Care, University Hospitals of Geneva, Switzerland, and Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva; 2 Department of Pediatrics, Children's Hospital of Geneva, Geneva; and 3 NovImmune, Geneva, Switzerland Myeloid differentiation factor-2 (MD-2) is a lipopolysaccharide (LPS)-binding protein usually coexpressed with and binding to Toll-like receptor 4 (TLR4), conferring LPS responsiveness of immune cells. MD-2 is also found as a soluble protein. Soluble MD-2 (sMD-2) levels are markedly elevated in plasma from patients with severe infections, and in other fluids from inflamed tissues. We show that sMD-2 is a type II acute-phase protein. Soluble MD-2 mRNA and protein levels are up-regulated in mouse liver after the induction of an acute-phase response. It is secreted by human hepatocytic cells and up-regulated by interleukin-6. Soluble MD-2 binds to Gram-negative but not Gram-positive bacteria, and sMD-2 secreted by hepatocytic cells is an essential cofactor for the activation of TLR4-expressing cells by Gram-negative bacteria. Soluble MD-2 opsonization of Gram-negative bacteria accelerates and enhances phagocytosis, principally by polymorphonuclear neutrophils. In summary, our results demonstrate that sMD-2 is a newly recognized type II acute-phase reactant, an opsonin for Gram-negative bacteria, and a cofactor essential for the activation of TLR4-expressing cells. This suggests that sMD-2 plays a key role in the host innate immune response to Gram-negative infections. CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this? This article has been cited by other articles: V. Jain, A. Halle, K. A. Halmen, E. Lien, M. Charrel-Dennis, S. Ram, D. T. Golenbock, and A. Visintin Phagocytosis and intracellular killing of MD-2 opsonized Gram-negative bacteria depend on TLR4 signaling Blood, May 1, 2008; 111(9): 4637 - 4645. [Abstract] [Full Text] [PDF]

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