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Thomas Poulsen

Complement C3 opsonization of Chlamydia trachomatis facilitates uptake in human monocytes

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  • Mads Lausen, Laboratory of Neurobiology, Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 3, 9220, Aalborg, Denmark.
  • ,
  • Gunna Christiansen
  • Nichlas Karred, Laboratory of Neurobiology, Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 3, 9220, Aalborg, Denmark.
  • ,
  • Robert Winther, Laboratory of Neurobiology, Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 3, 9220, Aalborg, Denmark.
  • ,
  • Thomas Bouet Guldbæk Poulsen
  • Yaseelan Palarasah, aDepartment of Cardiology, Hospital of South West Denmark, Esbjerg and Institute of Regional Health Research, University of Southern Denmark bDepartment of Clinical Biochemistry, Hospital of South West Denmark, Esbjerg and Unit for Thrombosis Research, Department of Public Health, University of Southern Denmark cDepartment of Cardiology, Skejby University Hospital, Aarhus, Denmark dDepartment of Cardiology, Odense University Hospital, Odense, Denmark eSiemens Healthcare Diagnostics Inc., Tarry town, NY, USA fSiemens Healthcare Diagnostics Products GmbH., Marburg, Germany.
  • ,
  • Svend Birkelund, Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 3b, 9220, Aalborg Ø, Denmark. Electronic address: sbirkelund@hst.aau.dk.

Chlamydia trachomatis is an obligate intracellular bacterium that causes severe infections, which can lead to infertility and ectopic pregnancy. Although both innate and adaptive immune responses are elicited during chlamydial infection the bacterium succeeds to evade host defense mechanisms establishing chronic infections. Thus, studying the host-pathogen interaction during chlamydial infection is of importance to understand how C. trachomatis can cause chronic infections. Both the complement system and monocytes play essential roles in anti-bacterial defense, and, therefore, we investigated the interaction between the complement system and the human pathogens C. trachomatis D and L2. Complement competent serum facilitated rapid uptake of both chlamydial serovars into monocytes. Using immunoelectron microscopy, we showed that products of complement C3 were loosely deposited on the bacterial surface in complement competent serum and further characterization demonstrated that the deposited C3 product was the opsonin iC3b. Using C3-depleted serum we confirmed that complement C3 facilitates rapid uptake of chlamydiae into monocytes in complement competent serum. Complement facilitated uptake did not influence intracellular survival of C. trachomatis or C. trachomatis-induced cytokine secretion. Hence, C. trachomatis D and L2 activate the complement system leading to chlamydial opsonization by iC3b and subsequent phagocytosis, activation and bacterial elimination by human monocytes.

Original languageEnglish
JournalMicrobes and Infection
Volume20
Issue6
Pages (from-to)328-336
Number of pages9
ISSN1286-4579
DOIs
Publication statusPublished - 1 Jun 2018

    Research areas

  • BORRELIA-BURGDORFERI, CELLS, Chlamydia trachomatis, Complement C3, INFECTION, LIPID RAFTS, MOUSE MACROPHAGES, MYCOBACTERIUM-TUBERCULOSIS, Monocytes, OUTER-MEMBRANE PROTEIN, PHAGOCYTOSIS, SEROVAR L2, WHOLE-BLOOD MODEL

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