title: Inhibition of complement and CD14 attenuates the Escherichia coli-induced inflammatory response in porcine whole blood.
abstract: The innate immune response is a double-edged sword in systemic inflammation and sepsis. Uncontrolled or inappropriate activation can damage and be lethal to the host. Several studies have investigated inhibition of downstream mediators, including tumor necrosis factor alpha (TNF-alpha) and interleukin-1beta (IL-1beta). Emerging evidence indicates that upstream inhibition is a better therapeutic approach for attenuating damaging immune activation. Therefore, we investigated inhibition of two central innate immune pathways, those of complement and CD14/Toll-like receptor 4 (TLR4)/myeloid differentiation protein 2 (MD-2), in a porcine in vitro model of Escherichia coli-induced inflammation. Porcine whole blood anticoagulated with lepuridin, which did not interfere with the complement system, was incubated with E. coli lipopolysaccharide (LPS) or whole bacteria. Inhibitors of complement and CD14 and thus the LPS CD14/TLR4/MD-2 receptor complex were tested to investigate the effect on the inflammatory response. A broad range of inflammatory readouts were used to monitor the effect. Anti-CD14 was found to saturate the CD14 molecule on granulocytes and completely inhibited LPS-induced proinflammatory cytokines in a dose-dependent manner. Anti-CD14 significantly reduced the levels of the E. coli-induced proinflammatory cytokines TNF-alpha and IL-1beta, but not IL-8, in a dose-dependent manner. No effect on bacterial clearance was seen. Vaccinia complement control protein and smallpox inhibitor of complement enzymes, two Orthopoxvirus-encoded complement inhibitors, completely inhibited complement activation. Furthermore, these agents almost completely inhibited the expression of wCD11R3, which is associated with CD18 as a beta2 integrin, on porcine granulocytes and decreased IL-8 levels significantly in a dose-dependent manner. As expected, complement inhibition reduced bacterial clearance. We conclude that inhibition of complement and CD14 attenuates E. coli-induced inflammation and might be used as a therapeutic regimen in gram-negative sepsis along with appropriate treatment with antibiotics.
authors.affiliation: Institute of Immunology, Rikshospitalet University Hospital, University of Oslo, Oslo, Norway. ebbtho@rr-research.no
authors.forename: Ebbe Billmann
authors.initials: EB
authors.lastname: Thorgersen
authors.forename: Anne
authors.initials: A
authors.lastname: Pharo
authors.forename: Karin
authors.initials: K
authors.lastname: Haverson
authors.forename: Anne K
authors.initials: AK
authors.lastname: Axelsen
authors.forename: Peter
authors.initials: P
authors.lastname: Gaustad
authors.forename: Girish J
authors.initials: GJ
authors.lastname: Kotwal
authors.forename: Georgia
authors.initials: G
authors.lastname: Sfyroera
authors.forename: Tom Eirik
authors.initials: TE
authors.lastname: Mollnes
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D018845:CD11 Antigens / Q000235:genetics / Q000378:metabolism; D003165:Complement System Proteins / Q000276:immunology*; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000502:physiology*; D005786:Gene Expression Regulation / Q000276:immunology; D006098:Granulocytes / Q000378:metabolism; D007113:Immunity, Innate; D007249:Inflammation / Q000097:blood / Q000378:metabolism*; D018950:Lipopolysaccharide Receptors / Q000276:immunology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D013552:Swine; D014763:Viral Matrix Proteins / Q000494:pharmacology
chemical_list: D000911:Antibodies, Monoclonal; D018845:CD11 Antigens; D016207:Cytokines; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; C532808:SPICE protein, variola virus; D014763:Viral Matrix Proteins; D003165:Complement System Proteins