Molecular Mechanisms Involved in Vascular Interactions of the Lyme Disease Pathogen in a Living Host

PLoS Pathogens

Paul Kubes¹  M. Ursula Norman¹  Brandie Millen¹  Tara J. Moriarty²  Ashley R. Dresser²  George Chaconas² 

[1] Department of Physiology & Biophysics, University of Calgary, Calgary, Alberta, Canada;Departments of Biochemistry & Molecular Biology and Microbiology & Infectious Diseases, University of Calgary, Calgary, Alberta, Canada

关键词: Borrelia burgdorferi;    Spirochetes;    Host-pathogen interactions;    Integrins;    Bacterial pathogens;    Protein interactions;    Venules;    Endothelium;   

DOI  :  10.1371/journal.ppat.1000169

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Hematogenous dissemination is important for infection by many bacterial pathogens, but is poorly understood because of the inability to directly observe this process in living hosts at the single cell level. All disseminating pathogens must tether to the host endothelium despite significant shear forces caused by blood flow. However, the molecules that mediate tethering interactions have not been identified for any bacterial pathogen except E. coli, which tethers to host cells via a specialized pillus structure that is not found in many pathogens. Furthermore, the mechanisms underlying tethering have never been examined in living hosts. We recently engineered a fluorescent strain of Borrelia burgdorferi, the Lyme disease pathogen, and visualized its dissemination from the microvasculature of living mice using intravital microscopy. We found that dissemination was a multistage process that included tethering, dragging, stationary adhesion and extravasation. In the study described here, we used quantitative real-time intravital microscopy to investigate the mechanistic features of the vascular interaction stage of B. burgdorferi dissemination. We found that tethering and dragging interactions were mechanistically distinct from stationary adhesion, and constituted the rate-limiting initiation step of microvascular interactions. Surprisingly, initiation was mediated by host Fn and GAGs, and the Fn- and GAG-interacting B. burgdorferi protein BBK32. Initiation was also strongly inhibited by the low molecular weight clinical heparin dalteparin. These findings indicate that the initiation of spirochete microvascular interactions is dependent on host ligands known to interact in vitro with numerous other bacterial pathogens. This conclusion raises the intriguing possibility that fibronectin and GAG interactions might be a general feature of hematogenous dissemination by other pathogens.

【 授权许可】

CC BY