title: Nanoscale Imaging Reveals a Tetraspanin-CD9 Coordinated Elevation of Endothelial ICAM-1 Clusters.
abstract: Endothelial barriers have a central role in inflammation as they allow or deny the passage of leukocytes from the vasculature into the tissue. To bind leukocytes, endothelial cells form adhesive clusters containing tetraspanins and ICAM-1, so-called endothelial adhesive platforms (EAPs). Upon leukocyte binding, EAPs evolve into docking structures that emanate from the endothelial surface while engulfing the leukocyte. Here, we show that TNF-α is sufficient to induce apical protrusions in the absence of leukocytes. Using advanced quantitation of atomic force microscopy (AFM) recordings, we found these structures to protrude by 160 ± 80 nm above endothelial surface level. Confocal immunofluorescence microscopy proved them positive for ICAM-1, JAM-A, tetraspanin CD9 and f-actin. Microvilli formation was inhibited in the absence of CD9. Our findings indicate that stimulation with TNF-α induces nanoscale changes in endothelial surface architecture and that--via a tetraspanin CD9 depending mechanism--the EAPs rise above the surface to facilitate leukocyte capture.
authors.affiliation: Medical faculty, University of Münster, Münster, Germany.
authors.forename: Jonas
authors.initials: J
authors.lastname: Franz
authors.affiliation: Institute-associated Research Group "Cell adhesion and cell polarity", Institute of Medical Biochemistry, ZMBE, 48419 Münster, Germany.
authors.forename: Benjamin F
authors.initials: BF
authors.lastname: Brinkmann
authors.affiliation: Medical faculty, University of Münster, Münster, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: König
authors.affiliation: Fluorescence Microscopy Facility Münster, Institute of Medical Physics and Biophysics, Center for Nanotechnology, University of Münster, Münster, Germany.
authors.forename: Jana
authors.initials: J
authors.lastname: Hüve
authors.affiliation: Centre for Internal Medicine, Hannover Medical School, Hannover, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Stock
authors.affiliation: Institute-associated Research Group "Cell adhesion and cell polarity", Institute of Medical Biochemistry, ZMBE, 48419 Münster, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Ebnet
authors.affiliation: Serend-ip GmbH, Centre for Nanotechnology, Münster, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Riethmüller
mesh_terms: D002448:Cell Adhesion / Q000187:drug effects; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism*; D007962:Leukocytes / Q000187:drug effects / Q000378:metabolism; D018625:Microscopy, Atomic Force; D060245:Tetraspanin 29 / Q000378:metabolism*; D059470:Tetraspanins / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D060245:Tetraspanin 29; D059470:Tetraspanins; D014409:Tumor Necrosis Factor-alpha; D018799:Intercellular Adhesion Molecule-1