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Contrary to other African trypanosomes Trypanosoma congolense bloodstream forms
specifically adhere to endothelial cells. Nothing is known about the receptors involved
and the biological significance of this phenomen. In this study we show that signal
transduction pathways are activated in human umbilical vein endothelial cells (HUVECs)
during trypanosomes adhesion.
Adhesion between Trypanosoma congolense and HUVECs is only transient, with a
maximum effect at 2 hours incubation time. After that the adhesion is declined. In
parallel to the increase and decrease of adhesion NF-kB is activated and IL-8 is secreted
into the medium. In addition, HUVECs produce reactive oxygen species (ROS) during
adhesion, as measured with pholasin. Preincubation of HUVECs with the antioxidants Nacetyl-
L-cysteine (NAC) and pyrrolidine dithiocarbamate (PDTC) and the NAD(P)H
oxidase inhibitor apocynin completely abolish NF-kB activation, IL-8 secretion and
Trypanosoma congolense adhesion. Thus, either ROS or NF-kB or both may be involved
in the regulation of the activity of the adhesion receptor.