TY - JOUR
T1 - Human genetic deficiencies reveal the roles of complement in the inflammatory network: lessons from nature
AU - Lappegård, Knut Tore
AU - Christiansen, Dorte
AU - Pharo, Anne
AU - Thorgersen, Ebbe Billmann
AU - Hellerud, Bernt Christian
AU - Lindstad, Julie
AU - Nielsen, Erik Waage
AU - Bergseth, Grethe
AU - Fadnes, Dag
AU - Abrahamsen, Tore G
AU - Høiby, E Arne
AU - Schejbel, Lone
AU - Garred, Peter
AU - Lambris, John D
AU - Harboe, Morten
AU - Mollnes, Tom Eirik
N1 - Keywords: Adolescent; Adult; Antigens, CD14; Case-Control Studies; Cell Adhesion; Complement Activation; Complement C2; Complement C5; Complement System Proteins; Escherichia coli; Female; Gram-Negative Bacteria; Humans; Immunity, Innate; Inflammation; Male; Models, Immunological; Monocytes; Neisseria meningitidis; Phagocytosis; Respiratory Burst; Thromboplastin
PY - 2009
Y1 - 2009
N2 - Complement component C5 is crucial for experimental animal inflammatory tissue damage; however, its involvement in human inflammation is incompletely understood. The responses to gram-negative bacteria were here studied taking advantage of human genetic complement-deficiencies--nature's own knockouts--including a previously undescribed C5 defect. Such deficiencies provide a unique tool for investigating the biological role of proteins. The experimental conditions allowed cross-talk between the different inflammatory pathways using a whole blood model based on the anticoagulant lepirudin, which does not interfere with the complement system. Expression of tissue factor, cell adhesion molecules, and oxidative burst depended highly on C5, mediated through the activation product C5a, whereas granulocyte enzyme release relied mainly on C3 and was C5a-independent. Release of cytokines and chemokines was mediated to varying degrees by complement and CD14; for example, interleukin (IL)-1beta and IL-8 were more dependent on complement than IFN-gamma and IL-6, which were highly dependent on CD14. IL-1 receptor antagonist (IL-1ra) and IFN-gamma inducible protein 10 (IP-10) were fully dependent on CD14 and inversely regulated by complement, that is, complement deficiency and complement inhibition enhanced their release. Granulocyte responses were mainly complement-dependent, whereas monocyte responses were more dependent on CD14. Notably, all responses were abolished by combined neutralization of complement and CD14. The present study provides important insight into the comprehensive role of complement in human inflammatory responses to gram-negative bacteria.
AB - Complement component C5 is crucial for experimental animal inflammatory tissue damage; however, its involvement in human inflammation is incompletely understood. The responses to gram-negative bacteria were here studied taking advantage of human genetic complement-deficiencies--nature's own knockouts--including a previously undescribed C5 defect. Such deficiencies provide a unique tool for investigating the biological role of proteins. The experimental conditions allowed cross-talk between the different inflammatory pathways using a whole blood model based on the anticoagulant lepirudin, which does not interfere with the complement system. Expression of tissue factor, cell adhesion molecules, and oxidative burst depended highly on C5, mediated through the activation product C5a, whereas granulocyte enzyme release relied mainly on C3 and was C5a-independent. Release of cytokines and chemokines was mediated to varying degrees by complement and CD14; for example, interleukin (IL)-1beta and IL-8 were more dependent on complement than IFN-gamma and IL-6, which were highly dependent on CD14. IL-1 receptor antagonist (IL-1ra) and IFN-gamma inducible protein 10 (IP-10) were fully dependent on CD14 and inversely regulated by complement, that is, complement deficiency and complement inhibition enhanced their release. Granulocyte responses were mainly complement-dependent, whereas monocyte responses were more dependent on CD14. Notably, all responses were abolished by combined neutralization of complement and CD14. The present study provides important insight into the comprehensive role of complement in human inflammatory responses to gram-negative bacteria.
U2 - 10.1073/pnas.0903613106
DO - 10.1073/pnas.0903613106
M3 - Journal article
C2 - 19717455
SN - 0027-8424
VL - 106
SP - 15861
EP - 15866
JO - Proceedings of the National Academy of Science of the United States of America
JF - Proceedings of the National Academy of Science of the United States of America
IS - 37
ER -