title: Toll-like receptor 3 signalling mediates angiogenic response upon shock wave treatment of ischaemic muscle.
abstract: OBJECTIVE
  Shock wave therapy (SWT) represents a clinically widely used angiogenic and thus regenerative approach for the treatment of ischaemic heart or limb disease. Despite promising results in preclinical and clinical trials, the exact mechanism of action remains unknown. Toll-like receptor 3, which is part of the innate immunity, is activated by binding double-stranded (ds) RNA. It plays a key role in inflammation, a process that is needed also for angiogenesis. We hypothesize that SWT causes cellular cavitation without damaging the target cells, thus liberating cytoplasmic RNA that in turn activates TLR3.
  
  
  RESULTS
  SWT induces TLR3 and IFN-β1 gene expression as well as RNA liberation from endothelial cells in a time-dependant manner. Conditioned medium from SWT-treated HUVECs induced TLR3 signalling in reporter cells. The response was lost when the medium was treated with RNase III to abolish dsRNAs or when TLR3 was silenced using siRNAs. In a mouse hind limb ischaemia model using wt and TLR3(-/-) mice (n = 6), SWT induced angiogenesis and arteriogenesis only in wt animals. These effects were accompanied by improved blood perfusion of treated limbs. Analysis of main molecules of the TLR3 pathways confirmed TLR3 signalling in vivo following SWT.
  
  
  CONCLUSIONS
  Our data reveal a central role of the innate immune system, namely Toll-like receptor 3, to mediate angiogenesis upon release of cytoplasmic RNAs by mechanotransduction of SWT.
authors.affiliation: Department of Cardiac Surgery, Innsbruck Medical University, Innsbruck, Austria.
authors.forename: Johannes
authors.initials: J
authors.lastname: Holfeld
authors.affiliation: Department of Cardiac Surgery, Innsbruck Medical University, Innsbruck, Austria.
authors.forename: Can
authors.initials: C
authors.lastname: Tepeköylü
authors.affiliation: Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Frankfurt am Main, Germany.
authors.forename: Christin
authors.initials: C
authors.lastname: Reissig
authors.affiliation: Department of Cardiac Surgery, Innsbruck Medical University, Innsbruck, Austria.
authors.forename: Daniela
authors.initials: D
authors.lastname: Lobenwein
authors.affiliation: Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Frankfurt am Main, Germany.
authors.forename: Bertram
authors.initials: B
authors.lastname: Scheller
authors.affiliation: Department of Cardiac Surgery, Innsbruck Medical University, Innsbruck, Austria.
authors.forename: Elke
authors.initials: E
authors.lastname: Kirchmair
authors.affiliation: Department of Cardiac Surgery, Innsbruck Medical University, Innsbruck, Austria.
authors.forename: Radoslaw
authors.initials: R
authors.lastname: Kozaryn
authors.affiliation: Department of Internal Medicine III, Innsbruck Medical University, Innsbruck, Austria.
authors.forename: Karin
authors.initials: K
authors.lastname: Albrecht-Schgoer
authors.affiliation: Department of Cardiac Surgery, Innsbruck Medical University, Innsbruck, Austria.
authors.forename: Christoph
authors.initials: C
authors.lastname: Krapf
authors.affiliation: Department of Anatomy and Cell Biology, Vienna Medical University, Vienna, Austria.
authors.forename: Karin
authors.initials: K
authors.lastname: Zins
authors.affiliation: Faculty of Medicine, Philipps University Marburg, Marburg, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Urbschat
authors.affiliation: Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Frankfurt am Main, Germany.
authors.forename: Kai
authors.initials: K
authors.lastname: Zacharowski
authors.affiliation: Department of Cardiac Surgery, Innsbruck Medical University, Innsbruck, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Grimm
authors.affiliation: Department of Internal Medicine III, Innsbruck Medical University, Innsbruck, Austria.
authors.forename: Rudolf
authors.initials: R
authors.lastname: Kirchmair
authors.affiliation: Department of Anesthesiology and Operative Intensive Care Medicine, Kepler University Hospital, Linz, Austria patrick.paulus@gmx.net.
authors.forename: Patrick
authors.initials: P
authors.lastname: Paulus
mesh_terms: D000818:Animals; D042783:Endothelial Cells / Q000378:metabolism*; D007113:Immunity, Innate / Q000276:immunology*; D007249:Inflammation / Q000378:metabolism*; D007511:Ischemia / Q000378:metabolism; D008297:Male; D040542:Mechanotransduction, Cellular / Q000502:physiology*; D008810:Mice, Inbred C57BL; D009389:Neovascularization, Pathologic / Q000378:metabolism*; D012330:RNA, Double-Stranded / Q000378:metabolism; D015398:Signal Transduction; D051196:Toll-Like Receptor 3 / Q000378:metabolism
chemical_list: D012330:RNA, Double-Stranded; C519703:TLR3 protein, mouse; D051196:Toll-Like Receptor 3
keywords: Angiogenesis; Shock wave therapy; Toll-like receptor 3