Open AccessReal‐time imaging of Toxoplasma ‐infected human monocytes under fluidic shear stress reveals rapid translocation of intracellular parasites across endothelial barriers
Author(s) -
Ueno Norikiyo,
Harker Katherine S.,
Clarke Elizabeth V.,
McWhorter Frances Y.,
Liu Wendy F.,
Tenner Andrea J.,
Lodoen Melissa B.
Publication year - 2014
Publication title -
cellular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.542
H-Index - 138
eISSN - 1462-5822
pISSN - 1462-5814
DOI - 10.1111/cmi.12239
Subject(s) - biology , toxoplasma gondii , endothelium , monocyte , leukocyte extravasation , microbiology and biotechnology , intracellular parasite , immunology , macrophage , intracellular , inflammation , antibody , in vitro , endocrinology , biochemistry
Summary Peripheral blood monocytes are actively infected by T oxoplasma gondii and can function as ‘ T rojan horses’ for parasite spread in the bloodstream. Using dynamic live‐cell imaging, we visualized the transendothelial migration ( TEM ) of T . gondii ‐infected primary human monocytes during the initial minutes following contact with human endothelium. On average, infected and uninfected monocytes required only 9.8 and 4.1 min, respectively, to complete TEM . Infection increased monocyte crawling distances and velocities on endothelium, but overall TEM frequencies were comparable between infected and uninfected cells. In the vasculature, monocytes adhere to endothelium under the conditions of shear stress found in rapidly flowing blood. Remarkably, the addition of fluidic shear stress increased the TEM frequency of infected monocytes 4.5‐fold compared to static conditions (to 45.2% from 10.3%). Infection led to a modest increase in expression of the high‐affinityconformation of the monocyte integrin Mac ‐1 (CD11b/CD18), and Mac ‐1 accumulated near endothelial junctions during TEM . Blocking Mac ‐1 inhibited the crawling and TEM of infected monocytes to a greater degree than uninfected monocytes, and blocking the Mac ‐1 ligand, ICAM ‐1, dramatically reduced crawling and TEM for both populations. These findings contribute to a greater understanding of parasite dissemination from the vasculature into tissues.