title: Salmon-derived thrombin inhibits development of chronic pain through an endothelial barrier protective mechanism dependent on APC.
abstract: Many neurological disorders are initiated by blood-brain barrier breakdown, which potentiates spinal neuroinflammation and neurodegeneration. Peripheral neuropathic injuries are known to disrupt the blood-spinal cord barrier (BSCB) and to potentiate inflammation. But, it is not known whether BSCB breakdown facilitates pain development. In this study, a neural compression model in the rat was used to evaluate relationships among BSCB permeability, inflammation and pain-related behaviors. BSCB permeability increases transiently only after injury that induces mechanical hyperalgesia, which correlates with serum concentrations of pro-inflammatory cytokines, IL-7, IL-12, IL-1α and TNF-α. Mammalian thrombin dually regulates vascular permeability through PAR1 and activated protein C (APC). Since thrombin protects vascular integrity through APC, directing its affinity towards protein C, while still promoting coagulation, might be an ideal treatment for BSCB-disrupting disorders. Salmon thrombin, which prevents the development of mechanical allodynia, also prevents BSCB breakdown after neural injury and actively inhibits TNF-α-induced endothelial permeability in vitro, which is not evident the case for human thrombin. Salmon thrombin's production of APC faster than human thrombin is confirmed using a fluorogenic assay and APC is shown to inhibit BSCB breakdown and pain-related behaviors similar to salmon thrombin. Together, these studies highlight the impact of BSCB on pain and establish salmon thrombin as an effective blocker of BSCB, and resulting nociception, through its preferential affinity for protein C.
authors.affiliation: Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Jenell R
authors.initials: JR
authors.lastname: Smith
authors.affiliation: Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Physiology, Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Galie
authors.affiliation: Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Physiology, Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: David R
authors.initials: DR
authors.lastname: Slochower
authors.affiliation: Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Christine L
authors.initials: CL
authors.lastname: Weisshaar
authors.affiliation: Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Physiology, Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Janmey
authors.affiliation: Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Neurosurgery, University of Pennsylvania, Philadelphia, PA 19104, USA. Electronic address: winkelst@seas.upenn.edu.
authors.forename: Beth A
authors.initials: BA
authors.lastname: Winkelstein
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002199:Capillary Permeability / Q000187:drug effects; D059350:Chronic Pain / Q000097:blood / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology; D016207:Cytokines / Q000097:blood / Q000276:immunology; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000276:immunology / Q000473:pathology; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D006930:Hyperalgesia / Q000097:blood / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology; D007249:Inflammation / Q000097:blood / Q000188:drug therapy / Q000276:immunology / Q000473:pathology; D008297:Male; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020011:Protective Agents / Q000737:chemistry / Q000302:isolation & purification / Q000627:therapeutic use*; D011486:Protein C / Q000276:immunology*; D051381:Rats; D012474:Salmon / Q000378:metabolism; D013116:Spinal Cord / Q000098:blood supply* / Q000187:drug effects / Q000276:immunology / Q000473:pathology; D013917:Thrombin / Q000737:chemistry / Q000302:isolation & purification / Q000627:therapeutic use*
chemical_list: D016207:Cytokines; D020011:Protective Agents; D011486:Protein C; D013917:Thrombin
keywords: Activated protein C; Blood–brain barrier; Nerve root injury; Pain; Thrombin