title: Neuraminidase alters red blood cells in sepsis.
abstract: OBJECTIVE
  To investigate the influence of neuraminidase, an enzyme that cleaves sialic acid from the red blood cell (RBC) membrane, on RBC shape and biochemistry in critically ill patients.
  
  
  METHODS
  Prospective, observational study and in vitro laboratory study.
  
  
  METHODS
  A 31-bed medico-surgical department of intensive care and a university-affiliated cell biology laboratory.
  
  
  METHODS
  Acutely ill patients with and without sepsis and healthy volunteers.
  
  
  METHODS
  Blood sampling in volunteers.
  
  
  RESULTS
  Neuraminidase activity was measured using a fluorescent assay. RBC shape was assessed by the second coefficient of dissymmetry of Pearson using a flow cytometry technique at 25 degrees C. Intraerythrocytic 2,3-diphosphoglycerate and lactate contents were also measured. Neuraminidase activity was significantly higher in septic patients compared with nonseptic patients and healthy volunteers (5.42 [4.85-6.00] vs. 4.53 [4.23-5.23] and 1.26 [0.83-1.83] mU/mL; all p < 0.05). Neuraminidase treatment modified the RBC shape in vitro in a dose-response fashion, and most of these alterations were present after 10 hours of incubation. Incubation of RBCs with phosphatidylinositol phospholipase C modified RBC shape and increased sialic acid concentrations in the supernatant, suggesting a leakage of neuraminidase from the RBC membrane. Alterations in shape were associated with increased 2,3-diphosphoglycerate (0.46 +/- 0.25 vs. 0.19 +/- 0.05 mumol/mL; p = 0.006) and lactate content (0.81 +/- 0.07 vs. 0.66 +/- 0.05 mmoL/L; p = 0.002).
  
  
  CONCLUSIONS
  In sepsis, desialylation under the influence of increased neuraminidase activity may contribute to the alterations in RBC rheology. Inhibition of neuraminidase may represent a new therapeutic option to ameliorate RBC rheology and perhaps oxygen delivery to the cells.
authors.affiliation: Department of Intensive Care, Erasme Hospital, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Michael
authors.initials: M
authors.lastname: Piagnerelli
authors.forename: Karim Zouaoui
authors.initials: KZ
authors.lastname: Boudjeltia
authors.forename: Alessandro
authors.initials: A
authors.lastname: Rapotec
authors.forename: Thibault
authors.initials: T
authors.lastname: Richard
authors.forename: Dany
authors.initials: D
authors.lastname: Brohée
authors.forename: Sajida
authors.initials: S
authors.lastname: Babar
authors.forename: Vanessa
authors.initials: V
authors.lastname: Bouckaert
authors.forename: Anne-Catherine
authors.initials: AC
authors.lastname: Simon
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Toko
authors.forename: Therese
authors.initials: T
authors.lastname: Walravens
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Vincent
authors.forename: Michel
authors.initials: M
authors.lastname: Vanhaeverbeek
mesh_terms: D000328:Adult; D000368:Aged; D002478:Cells, Cultured; D004912:Erythrocytes / Q000187:drug effects* / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009439:Neuraminidase / Q000494:pharmacology*; D011446:Prospective Studies; D018805:Sepsis / Q000097:blood*
chemical_list: D009439:Neuraminidase