Abstracts (complete list) - Wissenschaft Online

Andrea Mahr
Suppression of Dendritic Cell Activation by Annexin 1
on the Surface of Apoptotic Cells
Dendritic cells (DCs) are phagocytic cells that discriminate “non-self” from “self”
structures, and consequently initiate immunity or tolerance. Pathogenic components,
like bacteria-derived lipopolysaccharide (LPS), are recognized by Toll-Like Receptors
(TLRs) on the surface of DCs, leading to DC activation and secretion of proinflammatory
cytokines. This process can be inhibited by the uptake of apoptotic cells, the biggest
source of “self”-material. Inhibition is probably mediated by tolerogenic signals on the
surface of apoptotic cells, but the molecules relevant for this process are not yet well
defined. A candidate protein is annexin 1, which is externalized by early apoptotic cells.
In this study, it has been found that pre-incubation of DCs with apoptotic cells or
purified recombinant annexin 1 before TLR stimulation could reduce the transcriptional
upregulation and secretion of proinflammatory cytokines.
Correspondingly, annexin 1 led to a substantial decrease of LPS-induced TLR signal
transduction.
The detailed analysis of annexin 1 function may lead to a more advanced understanding
of the regulation of TLR signaling, and would give valuable insight into a potential
mechanism of peripheral non-responsiveness.