Tm. Lin et al., Monocyte-endothelial cell coculture enhances infection of endothelial cells with Chlamydia pneumoniae, J INFEC DIS, 181(3), 2000, pp. 1096-1100
To determine the mechanism(s) by which Chlamydia pneumoniae homes to and es
tablishes persistent infection in atheromatous lesions, the effect of the i
nteraction of monocytes/mcarophages (U937 cells) with human umbilical vein
endothelial cells (HUVECs) and transformed human arterial endothelial cells
(HMEC-1s) on the susceptibility of endothelial cells to infection with C.
pneumoniae was investigated. Infection was enhanced 4.7-fold (HUVECs) and 4
.4-fold (HMEC-1s) after coculture at monocyte-to-endothelial cell ratios of
5 and 2.5, respectively. U937 cells also directly transmitted infection to
the endothelial cells, and addition of U937 cell-conditioned media dose-de
pendently enhanced the infectivity 2.0- to 2.5-fold. The stimulation of inf
ectivity was specific to endothelial cells, because coculturing of monocyte
s with epithelial cells did not enhance the susceptibility of epithelial ce
lls to infection. The susceptibility of endothelial cells to infection with
C. trachomatis and C. psittaci was not enhanced by the monocyte-derived fa
ctor(s).