title: Stimulation of platelet apoptosis by peptidoglycan from Staphylococcus aureus 113.
abstract: Peptidoglycan (PGN), a component of bacterial cell wall and belonging to "Microbe-Associated Molecular Patterns" (MAMP) triggers host reactions contributing to the pathophysiology of infectious disease. Host cell responses to PGN exposure include apoptosis. Bacterial infections may result in activation of blood platelets and thrombocytopenia. The present study explored, whether HPLC-purified fractions of PGNs from Staphylococcus aureus 113 triggers apoptosis of platelets. To this end platelets were exposed to PGN fractions and annexin-V binding determined to depict cell membrane scrambling, DiOC6 fluorescence to estimate depolarization of mitochondrial potential, Fluo-3AM staining for intracellular Ca(2+) activity ([Ca(2+)](i)) and immunofluorescence to quantify protein abundance of active caspase-3. As a result, a 30 min exposure to monomeric fraction (mPGN) (≥50 ng/ml) was followed by annexin-V binding, paralleled by increase of [Ca(2+)](i), mitochondrial depolarization, caspase-3 activation and integrin α(IIb)β(3) upregulation. The annexin-V binding was significantly blunted by anti-TLR-2 antibodies, in absence of extracellular Ca(2+), and by pancaspase inhibitor zVAD-FMK (1 μM). In conclusion, PGN triggers apoptosis of platelets in activation-dependent manner, characterized by mitochondrial depolarization, caspase-3 activation and cell membrane scrambling.
authors: Department of Physiology, University of Tübingen, Gmelinstr. 5, 72076, Tübingen, Germany.
authors: Syeda T
authors: ST
authors: Towhid
authors: Mulugeta
authors: M
authors: Nega
authors: Eva-Maria
authors: EM
authors: Schmidt
authors: Evi
authors: E
authors: Schmid
authors: Till
authors: T
authors: Albrecht
authors: Patrick
authors: P
authors: Münzer
authors: Oliver
authors: O
authors: Borst
authors: Friedrich
authors: F
authors: Götz
authors: Florian
authors: F
authors: Lang
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017304:Annexin A5 / Q000378:metabolism; D000906:Antibodies / Q000276:immunology; D017209:Apoptosis / Q000187:drug effects*; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism*; D053148:Caspase 3 / Q000378:metabolism; D061945:Caspase Inhibitors / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D004789:Enzyme Activation; D006801:Humans; D039421:Integrin alpha2 / Q000096:biosynthesis; D008928:Mitochondria / Q000378:metabolism; D010457:Peptidoglycan / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000737:chemistry*; D051195:Toll-Like Receptor 2 / Q000276:immunology
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D017304:Annexin A5; D000906:Antibodies; D061945:Caspase Inhibitors; D039421:Integrin alpha2; D010457:Peptidoglycan; D051195:Toll-Like Receptor 2; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D053148:Caspase 3