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Dynamisches Testsystem zur Untersuchung Selektin-inhibierender Substanzen als potentiell antiinflammatorische Verbindungen

Gabriele Schumacher a, Matthias Höpfner a, Jan Vogel a, Udo Bakowsky b, Takao Ikami c, Ulrich Rothe d und Gerd Bendas a

Fachbereich Pharmazie, Martin-Luther-Universität Halle a, Halle, Department of Cell Membrane Research, University Groningen b, Groningen (Niederlande), Sanwa Kagaku Kenkyusho Co. Ltd. c, Hokuseicho (Japan), und Institut für Physiologische Chemie, Martin-Luther-Universität Halle d, Halle

Herrn Professor Dr. Peter Nuhn, Universität Halle, anläßlich seines 65. Geburtstages in Hochachtung gewidmet

A Dynamic Test System to Investigate Selectin-induced Cell Rolling in Order to Search for New Antiinflammatory Compounds

The accumulation of leukocytes in the vasculature at inflammatory sites and their emigration into the local tissue is a multistep process, which is mediated by various cell adhesion molecules. The selectins, a family of three carbohydrate-binding proteins, initiate the adhesion by mediating tethering and rolling of leukocytes along the vessel wall in the vascular shear flow. Because of their central role in the immune defence, a blocking of selectins appears as a novel therapeutical strategy for systematically controlling pathological inflammations at an early stage. In order to find selectin inhibitors serving as new potential antiinflammatory drugs, we simulate the molecular mechanisms of selectin binding in a dynamic model system. The selectin-induced adhesion and rolling of cells on a model membrane exposed to a shear rate of a flow chamber was analyzed by confocal fluorescence microscopy. On that basis we analyzed the selectin inhibitory efficiency of a series of carbohydrate compounds, which are structurally derived from the tetrasaccharide Sialyl Lewisx. In contrast to the common static binding assays, inhibitors in our dynamic system block the selectin-mediated cell rolling in agreement with the physiological situation.
The inhibitory potency of these compounds was exactly manifested in reduced cell binding events and in increased rolling velocity. Compared to the results in a static binding assay, distinct differences could be detected, which were explained by the dominance of different binding forces in both systems. Consequently, the structure-activity relationships of these compounds differ under both static and dynamic conditions. Therefore, the results confirm the importance to consider the physiological shear force conditions in the inhibitor screening. Since the dynamic system further offers a great variety in the choice of the ligand-receptor pairs it is an excellent tool for the inhibitor screening.

Key Words Adhäsionsmodell · Entzündung · Kohlenhydrat · Selektine · Sialyl Lewis X · Zellrollen