title: Interaction of Bacteroides fragilis and Bacteroides thetaiotaomicron with the kallikrein-kinin system.
abstract: Many bacterial pathogens interfere with the contact system (kallikrein-kinin system) in human plasma. Activation of this system has two consequences: cleavage of high-molecular-mass kininogen (HK) resulting in release of the potent proinflammatory peptide bradykinin, and initiation of the intrinsic pathway of coagulation. In this study, two species of the Gram-negative anaerobic commensal organism Bacteroides, namely Bacteroides fragilis and Bacteroides thetaiotaomicron, were found to bind HK and fibrinogen, the major clotting protein, from human plasma as shown by immunoelectron microscopy and Western blot analysis. In addition, these Bacteroides species were capable of activating the contact system at its surface leading to a significant prolongation of the intrinsic coagulation time and also to the release of bradykinin. Members of the genus Bacteroides have been known to act as opportunistic pathogens outside the gut, with B. fragilis being the most common isolate from clinical infections, such as intra-abdominal abscesses and bacteraemia. The present results thus provide more insight into how Bacteroides species cause infection.
authors.affiliation: Department of Life Sciences and Materials and Surface Science Institute, University of Limerick, Limerick, Ireland.|Department of Clinical Sciences, Lund, Division of Infection Medicine, Lund University, SE-22184 Lund, Sweden.
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: Murphy
authors.affiliation: Department of Clinical Sciences, Lund, Division of Infection Medicine, Lund University, SE-22184 Lund, Sweden.
authors.forename: Matthias
authors.initials: M
authors.lastname: Mörgelin
authors.affiliation: Department of Life Sciences and Materials and Surface Science Institute, University of Limerick, Limerick, Ireland.
authors.forename: Jakki C
authors.initials: JC
authors.lastname: Cooney
authors.affiliation: Department of Clinical Sciences, Lund, Division of Infection Medicine, Lund University, SE-22184 Lund, Sweden.
authors.forename: Inga-Maria
authors.initials: IM
authors.lastname: Frick
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D001439:Bacteroides / Q000378:metabolism* / Q000472:pathogenicity; D001441:Bacteroides fragilis / Q000378:metabolism* / Q000472:pathogenicity; D001777:Blood Coagulation; D001920:Bradykinin / Q000378:metabolism*; D005340:Fibrinogen / Q000378:metabolism*; D006801:Humans; D016234:Kallikrein-Kinin System / Q000502:physiology*; D007610:Kallikreins / Q000378:metabolism; D007704:Kininogens / Q000378:metabolism*; D007705:Kinins / Q000378:metabolism
chemical_list: D001425:Bacterial Outer Membrane Proteins; D007704:Kininogens; D007705:Kinins; D005340:Fibrinogen; D007610:Kallikreins; D001920:Bradykinin