title: Plasminogen in cerebrospinal fluid originates from circulating blood.
abstract: BACKGROUND
  Plasminogen activation is a ubiquitous source of fibrinolytic and proteolytic activity. Besides its role in prevention of thrombosis, plasminogen is involved in inflammatory reactions in the central nervous system. Plasminogen has been detected in the cerebrospinal fluid (CSF) of patients with inflammatory diseases; however, its origin remains controversial, as the blood-CSF barrier may restrict its diffusion from blood.
  
  
  METHODS
  We investigated the origin of plasminogen in CSF using Alexa Fluor 488-labelled rat plasminogen injected into rats with systemic inflammation and blood-CSF barrier dysfunction provoked by lipopolysaccharide (LPS). Near-infrared fluorescence imaging and immunohistochemistry fluorescence microscopy were used to identify plasminogen in brain structures, its concentration and functionality were determined by Western blotting and a chromogenic substrate assay, respectively. In parallel, plasminogen was investigated in CSF from patients with Guillain-Barré syndrome (n = 15), multiple sclerosis (n = 19) and noninflammatory neurological diseases (n = 8).
  
  
  RESULTS
  Endogenous rat plasminogen was detected in higher amounts in the CSF and urine of LPS-treated animals as compared to controls. In LPS-primed rats, circulating Alexa Fluor 488-labelled rat plasminogen was abundantly localized in the choroid plexus, CSF and urine. Plasminogen in human CSF was higher in Guillain-Barré syndrome (median = 1.28 ng/μl (interquartile range (IQR) = 0.66 to 1.59)) as compared to multiple sclerosis (median = 0.3 ng/μl (IQR = 0.16 to 0.61)) and to noninflammatory neurological diseases (median = 0.27 ng/μl (IQR = 0.18 to 0.35)).
  
  
  CONCLUSIONS
  Our findings demonstrate that plasminogen is transported from circulating blood into the CSF of rats via the choroid plexus during inflammation. Our data suggest that a similar mechanism may explain the high CSF concentrations of plasminogen detected in patients with inflammation-derived CSF barrier impairment.
authors.forename: Anna
authors.initials: A
authors.lastname: Mezzapesa
authors.forename: Cyrille
authors.initials: C
authors.lastname: Orset
authors.forename: Laurent
authors.initials: L
authors.lastname: Plawinski
authors.forename: Loic
authors.initials: L
authors.lastname: Doeuvre
authors.forename: Sara
authors.initials: S
authors.lastname: Martinez de Lizarrondo
authors.forename: Guglielmina
authors.initials: G
authors.lastname: Chimienti
authors.forename: Denis
authors.initials: D
authors.lastname: Vivien
authors.forename: Alexandre
authors.initials: A
authors.lastname: Mansour
authors.forename: Sabrina
authors.initials: S
authors.lastname: Matà
authors.forename: Gabriella
authors.initials: G
authors.lastname: Pepe
authors.forename: Eduardo
authors.initials: E
authors.lastname: Anglés-Cano
mesh_terms: D000818:Animals; D001812:Blood-Brain Barrier / Q000502:physiology*; D015153:Blotting, Western; D006801:Humans; D007249:Inflammation / Q000097:blood* / Q000134:cerebrospinal fluid*; D008297:Male; D008856:Microscopy, Fluorescence; D010958:Plasminogen / Q000134:cerebrospinal fluid*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D010958:Plasminogen